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Combi PAL SPME Manual

1. Martos Perry A Saraullo A Pawliszyn J Mindrup R Shirey R Moder M Popp P Pawliszyn Motlagh S Pawliszyn J Nilsson F Pelusio L Montanarella B Larsen S Facchetti and J Madsen Nolan L Shirey R Mindrup R Okeyo P Snow N Combi PAL YEAR 1996 1996 1995 1995 1995 1996 1996 1997 1997 1994 1996 1996 1997 1998 1997 1993 1998 1993 1995 1994 1997 TITLE Analysis Of Pesticides In Environmental Water Samples By Solid Phase Micro Extraction High Performance Liquid Chromatography Trace Analysis Of Hetero Aromatic Compounds NSO In Water And Polluted Groundwater By Solid Phase Micro Extraction SPME Detection of Ten Local Anaesthetics in Human Blood Using Solid Phase Microextraction SPME and Capillary Gas Chromatography Simple Extraction of Tricyclic Antidepressants in Human Urine by Headspace Solid Phase Microextraction Detection of Cocaine in Human Urine by Solid Phase Microextraction and Capillary Gas Chromatography with Nitrogen Phosphorous Detection Quantitative Analysis Of Fuel Related Hydrocarbons In Surface Water And Wastewater Samples By Solid Phase Microextraction Detection of Organophosphate Pesticides in Human Body Fluids by Headspace Solid Phase Microextraction and Capillary Gas Chromatography with Nitrogen Phosphorous Detection On Line Determination of Organophosphorus Pesticides in Water by Solid
2. Optimizing Solid Phase Microextraction Gas Chromatographic Injections REFERENCE J CHROMATOGR A754 NOs 1 and 2 PP 137 144 J HIGH RESOL CHROMATOGR 19 11 PP 627 632 Jpn J Forensic Toxicol Vol 13 3 pp 182 188 Jpn J Forensic Toxicol Vol 13 1 pp 25 30 Jpn J Forensic Toxicol Vol 13 3 pp 207 210 ANAL CHEM 68 1 PP 144 55 Chromatographia Vol 42 3 4 PP 135 140 J High Resol Chromatogr 20 pp 487 492 Anal Chem 69 pp 3899 3906 J CHROMATOGR SCI VOL 32 8 PP 317 22 J CHROMATOGR A 736 1 and 2 PP 219 228 J CHROMATOGR 723 1 PP 111 22 Anal Chem 69 pp 206 215 Anal Chem 70 pp 2311 2320 ANAL CHEM 69 3 PP 402 408 PROC WATER QUAL TECHNOL CONF PT 2 PP 1545 1565 J Microcolumn Sep 10 pp 225 234 Analytica Chimica Acta Vol 284 pp265 273 J HIGH RESOL CHROMATOGR VOL 18 PP 617 624 PROC WATER QUAL TECHNOL CONF PART 2 PP 1761 72 LC GC 15 pp 1130 1136 21 AUTHOR S Otu E O Pawliszyn J Pan L Adams M Pawliszyn J Pan L Chong M Pawliszyn J Pan L Pawliszyn J PAWLISZYN J Pelusio F Nilsson T Montanarella L Tilio R Larsen B Facchetti S Madsen J O Penton Z Penton Z Penton Z Penton Z Potter D W Pawliszyn j Saraullo A Martos P A Pawliszyn J Sarna l P Webster G R B Friesen Fischer M R Ranjan R S Schaefer B
3. the analysis of the beer samples with the ion trap detector after SPME sampling using the same column and the same chromatographic conditions described here The ion trap chromatograms were studied and one additional peak was identified peak 7 Figure 2 mass 106 1 Propanol 3 methylthio Figure 2 Mass spectra of peak 7 top identified in a search NIST 92 library Conditions are in SPME Application Note 15 Conclusions SPME combined with the PFPD is useful for generating profiles of the sulfur compounds in beer Some of the later eluting sulfur compounds could be identified if the effluent from the column were split between the ion trap detector and the PFPD References 1 SPME Application Note 15 Determining Volatiles in Beer with Automated SPME and GC MS ECD 2 GC MS Advantage Note 11 Maximize Information by Splitting Between the lon Trap Mass Spectrometer and a GC Detector 92 03 91483500 1 Quantitative Determination of Vinyl S P M E Chloride in a Polymer with Automated SPME Varian Application Note Zelda Penton Number 17 Varian Chromatography Systems Key Words SPME 8200 Standalone Polymers Volatiles in solid samples can easily be extracted with SPME but accurate quantitation can be quite difficult Multiple headspace extraction a technique that was originally developed for the quantitative determination of monomers in a polymer with static headspace 1 can also be applie
4. 69 2 PP 196 205 TRENDS ANAL CHEM VOL 14 3 PP 113 122 J AGRIC FOOD CHEM VOL 43 PP 2138 2143 FOOD TESTING amp ANALYSIS 2 3 PP 16 18 CAN SOC FORENS SCI J 30 1 PP7 12 Advances in Chromatography Vol 37 edited by Brown and Grushka Marcel Dekker NY pp 205 236 PROC WATER QUAL TECHNOL CONFPT 1 PP 1027 33 ENVIRON SCI TECHNOL VOL 28 2 PP 298 305 ANAL CHEM 69 11 PP 1992 1998 J CHROMATOGR A VOL 677 1 PP 201 5 FRESENIUS J ANAL CHEM 1995 VOL 352 5 PP 535 6 Jpn J Forensic Toxicol Vol 13 3 pp 211 215 J HIGH RESOLUT CHROMATOGR VOL 18 8 PP 495 9 KANKYO KAGAKU VOL 4 2 PP 496 7 J High Resolut Chromatogr Vol 20 2 pp 77 80 Fresenius J Anal Chem vol 354 pp 587 591 ANAL CHEM VOL 67 3 PP 600 5 Chromatographia Vol 42 5 6 pp 313 317 LC GC VOL 13 P 83 03 914835 00 1 AUTHOR S YEAR Yang X Peppard T 1994 Yang X Peppard T 1995 Yashiki M Nagasawa N 1995 Kojima T Miyazaki T Iwasaki Y Young R Lopez Avila V 1996 Beckert W F Zhang Z Pawliszyn J 1996 Zhang Z Pawliszyn J 1995 Zhang Z Pawliszyn J 1993 Zhang Z Pawliszyn J 1993 Zhang Z Poerschmann J 1996 Pawliszyn j Zhang Z Yang M 1994 J Pawliszyn J Zhang Z Yang M 1994 Pawliszyn J Combi PAL TITLE Solid Phase Microextraction For Flavor Analysis Solid Phase Microextrac
5. Engewald W Seno H Kumazawa T Ishii A Nishikawa M Hattori H Suzuki O Shirey R E Shirey R E Snow N H Okeyo P Tutschku S Mothes S Wennrich R Wittkamp B L Tilotta D C Xu N Vandegrift S Sewell G W Yang X Peppard T 22 YEAR 1993 1995 1997 1997 1995 1995 1996 1997 1996 1994 1994 1997 1994 1995 1995 1995 1994 1997 1996 1995 1996 1995 TITLE Solid Phase Micro Extraction Of Metal lons Determination Of Fatty Acids Using Solid Phase Microextraction Determination of Amines in Air and Water using Derivatizaion Combined with Solid Phase Microextraction Derivatization Solid Phase Microextraction New Approach To Polar Analytes New Directions In Sample Preparation For Analysis Of Organic Compounds Headspace Solid Phase Microextraction Analysis Of Volatile Organic Sulfur Compounds In Black And White Truffle Aroma Flavor Volatiles In A Fruit Beverage With Automated SPME Blood Alcohol Determination With Solid Phase Microextraction SPME A Comparison With Static Headspace Sampling Sample Preparation for Gas Chromatography with Solid Phase Extraction and Solid Phase Microextraction Determination Of Volatile Organics In Water By GC With Solid Phase Microextraction Rapid Determination Of Polyaromatic Hydrocarbons And Polychlorinated Biphenyls In Water Using Solid Phase Microextraction And GC MS Wa
6. F4 Home and repeat Step 1 5 Install the plunger holder into the injection unit Figure 4 left 6 Install a fiber assembly in the fiber holder and place it in the SPME adapter Figure 4 right Pull up the plunger so that the fiber is completely withdrawn into the protective needle 7 Place the SPME adapter partially into the injection unit In order to do this bend the top of the SPME adapter foreward slightly Figure 5A and thread the protective needle carefully through the upper and lower needle guides at the bottom of the injection unit 8 Push the plunger down so that approximately 1 5 to 2 cm of the fiber and fiber support rod are exposed 9 Place the plunger crosspiece into the plunger holder Allow the syringe adapter to click into place by magnetic force against the syringe carrier 10 Tighten the plunger retaining screw against the plunger crosspiece Figure 5B and press Continue Combi PAL 7 Figures 5A and 5B Installation of the fiber adapter in the Combi PAL injection unit Note Reverse the above procedure to remove the fiber Be sure to pull up the plunger of the fiber holder so that the unprotected fiber is not pulled through the upper and lower needle guides Standby position of the fiber In this step the end of the fiber is set so that it is just barely withdrawn into the protective needle This will minimize coring when penetrating vial or injector septa From the Job Queue page enter the
7. 0 19 5 38 4 chloro 3 methylphenol 0 15 6 17 2 4 5 trichlorophenol 0 21 5 55 2 4 6 trichlorophenol 0 20 6 80 2 4 dinitrophenol 1 28 4 88 4 nitrophenol 1 15 4 42 2 3 4 6 tetrachlorophenol 0 35 7 66 2 methyl 4 6 dinitrophenol 0 49 2 67 pentachlorophenol 0 95 10 02 dinoseb 0 65 8 01 Table 1 Minimum detectable quantities S N 4 and area count precision at 100 ppb of phenols in water with SPME sampling and agitation of the fiber Combi PAL 73 Conclusions With agitation the scope of automated SPME has been extended to semi volatiles Phenols with boiling points up to well over 300 C could be detected in water at levels below 1 ppb with FID detection Sample preparation was minimal The ruggedness of the SPME technique was demonstrated here During this study only one fiber was used There was no sign of deterioration of performance after repeated immersions approximately 80 runs in water that was at pH 2 and was saturated with sodium sulfate The 1078 injector did not require maintenance the same insert and septum were used throughout the project Reference 1 C L Arthur L M Killam S Motlagh M Lim D W Potter and J Pawliszyn ANALYSIS OF SUBSTITUTED BENZENE COMPOUNDS IN GROUNDWATER USING SOLID PHASE MICROEXTRACTION Environ Sci Technol 26 5 1992 pp 979 983 74 03 91483500 1 Performance of Automated SPME S P M E A Comparison of Results with an Interlaboratory Varian Application Note GCMS Pesticide Stu
8. 22 mL vials for duplicate SHS analysis and two 400 uL aliquots were added to 2 mL vials for duplicate SPME determination The purpose of the relatively high dilution was to minimize matrix differences between the various samples and the standards Figure 3 compares SHS and SPME results on 15 samples The samples included an aqueous ethanol control from the College of American Pathologists The target value was 101 mg dL the value determined with SHS was 97 7 and 102 7 with SPME When a sample of unspiked water was analyzed with SPME after a standard there was no evidence of ethanol carryover with SHS carryover was 0 8 Slope 1 020 Intercept 2 73 r 0 997 3 E 0 2 gt Ww a YN 100 150 SHS values mg dL Figure 3 Comparing ethanol in blood and urine samples determined with SPME and SHS The 15 samples included 12 blood and 2 urine specimens and an aqueous control The samples were diluted with internal standard Combi PAL 65 Conclusions SPME is a practical technique for determination of ethanol in blood or urine with several practical advantages over SHS In the study described here the SPME system was not thermostatted however the use of a low molecular weight alcohol as internal standard compensates for variations in temperature in this application 1 2 To reduce run time sampling was interrupted before equilibrium was achieved nevertheless the precise timing of the automated system assured
9. SPME after headspace and liquid sampling are shown in Figure 3 These results are totally unlike observations made with conventional static headspace sampling When the sample was analyzed with heated headspace at 85 C there was no response to the phenols or PNA s but with SPME headspace sampling at ambient temperature there was a strong response to these compounds With SPME equilibrium is established between three phases and when one considers the strong affinity of the fiber for aromatic compounds it is not surprising that there would be a good response to these compounds in spite of their low volatility 1 4 1 2 1 0 0 8 0 6 0 4 0 2 0 0 Figure 3 Responses for each of the components in test sample 2 were determined after headspace sampling over 0 8 mL and liquid sampling of 1 2 mL Adsorption times were 10 minutes with two minutes desorption The bars represent the FID response after headspace sampling divided by the response from liquid sampling These values were then multiplied by 1 5 to correct for the difference in sample volume Relative response SPME headspace to SPME liquid MeCl2 Chloroform Benzene Dioxane Toluene m Xylene 1 2 4 Trimethylbenzene o Nitrophenol 2 6 Dimethylphenol p Chlorophenol 2 4 6 Trichlorophenol Acenaphthene Phenanthrene Linearity and Detection Limits With Various Sample Introduction Methods Linearity of response with headspace and liquid SPME sampling was veri
10. SPME fiber is more likely to result in septum failure A septumless injedibr seal such as the Merlin Microseal Figure 2 is highly recommended Figure 2 The Merlin Microseal can be installed in a GC injector in place of a septum The device contains a duckbill that allows a needle to enter the injector without leaking This is available from Varian for the 1078 1079 injector and from other vendors for non Varian injectors Originally Supelco used 24 gauge tubing in manufacturing SPME fiber assemblies but 23 gauge tubing was required for the Merlin Microseal Both gauges are now available The higher the gauge number the narrower the outer diameter 4 03 914835 00 1 It is possible to use a conventional GC septum with SPME To minimize septum failure the following procedure is recommended Install a new septum Puncture the septum with a SPME protective needle Figure 1 three or four times Remove and inspect the new septum Pull off and discard any loose particles of septum material POonn Reinstall the septum The user should monitor the head pressure on the column as the protective needle enters and leaves the injector to verify the integrity ofthe seal A subtle leak will be indicated by shifts in retention time no peaks or poor area count precision and or the presence of air in a mass spectrometer Injector Temperature Although temperature programmable injectors have become popular for minimizing
11. Varian GC Application Note 50 58 03 91483500 1 Determination of Trace Methanol in a Caustic S P M E Industrial Product with Automated Solid Phase Varian Application Note Microextraction SPME Number 8 Zelda Penton Varian Chromatography Systems Key Words Solid Phase Microextraction SPME 8200 AutoSampler Methanol Industrial Applications A company was required to monitor trace levels of methanol in a proprietary liquid product The product contained 40 NaOH and other salts therefore it was extremely corrosive and viscous Some of the components in the product rendered it potentially reactive Automated solid phase microextraction SPME offered a possible solution for routine analysis of this sample the sample could not be safely analyzed with an automated static headspace system A sample containing approximately 400 ppm methanol was spiked with various levels of methanol and analyzed with SPME It was demonstrated with excellent linearity and precision data that SPME offered a practical solution to this difficult analytical problem methanol 0 51 min Figure 1 Chromatogram of the headspace over the unspiked caustic sample Combi PAL 59 Instrumentation and Conditions Instruments Column GC Conditions Automated SPME Conditions Sample Handling Varian 3600 CX GC with a 1078 split splitless temperature programmable injector FID and PC controlled 8200 AutoSampler The Star workst
12. decomposition of labile compounds and for eliminating discrimination based on volatility SPME fibers are generally desorbed under hot isothermal conditions Rapid desorption from the fiber is necessary for sharp peaks without sample carryover Injector temperature is normally 10 20 C below the temperature limit of the fiber and or the GC column usually 200 to 280 C Sample Vials Many SPME applications will require heating of the sample For these applications only vials recommended for the Combi PAL should be used These vials are 10 mL and 20 mL with magnetic crimp top caps and an 8 mm opening Two mL vials with magnetic caps are also available however these are not recommended as the holes in the cap are small and fiber breakage is possible Special adapters are required for the agitator when using 10 mL and 2 mL vials The adapters for the 10 mL vials are shipped with the instrument 3 For SPME sampling in the tray without heating or agitation 2 10 or 20 mL vials without magnetic caps may be used Combi PAL 5 Setting up the Combi PAL for SPME Refer to the Combi PAL system User Manual for installation of the Combi PAL and for setting the x y z parameters of the agitator tray holders trays and GC injectors FiberExp position In order for the SPME cycle to operate correctly it is necessary for the injection unit of the Combi PAL to be positioned next to the agitator just before the extraction This position has
13. good precision At the present time it appears that there are additional practical applications for SPME in the toxicology laboratory These include determination of several other volatiles in blood as well as relatively non volatile compounds such as ethylene glycol 3 References 1 The Advantages of Automated Blood Alcohol Determination by Headspace Analysis Machata G Z Rechtsmed 75 1975 pp 229 234 2 Headspace Measurement of Ethanol in Blood by Gas Chromatography with a Modified Autosampler Penton Z Clinical Chemistry 31 1985 pp 439 441 3 Michael Butler Office of the Chief Medical Examiner North Carolina Department of Environment Health and Natural Resources studies in progress Dr Randall Baselt Chemical Toxicology Institute Foster City CA provided blood and urine samples and Gary C Harmor Serological Research Institute Richmond CA provided ethanol free blood These contributions are gratefully acknowledged 66 03 91483500 1 Rapid Analysis of BTEX and TPH in Water using Solid SPME Phase Microextraction SPME and FasiGC Varian Application Note Number 10 Joy Jennison Dr Colin P R Jennison Varian Canada Applications Lab Key Words FastGC SPME 8200CX BTEX Solid Phase Microextraction SPME and FastGC have been coupled together to enable very rapid simple analysis of benzene toluene ethyl benzene and xylenes BTEX and volatile total petroleum hydrocarbons TPH in
14. in Process Water Using Solid S P M E Phase Microextraction ipi Varian Application Note Number 5 Joyce Jennison and Colin P R Jennison Varian Canada Key Words Solid Phase Microextraction SPME Therminol Biphenyl Diphenyl oxide Water It is a fast simple solvent free extraction Organics Introduction are adsorbed from an aqueous sample onto a fused silica fiber coated or bonded with a layer of liquid phase in this example polydimethylsiloxane After adsorption the fiber is withdrawn into a metal sheath needle which protects it during withdrawal from the septum vial The needle is then inserted through the septum into a hot injector the fiber extended and the analytes thermally desorbed to the GC column For the purpose of this method development of the entire extraction and desorption process was automated with the use of standard 2 mL autosampler vials a Varian 8200 CX AutoSampler and the appropriate software 4 229 Instrumentation and Conditions Instrument Varian Star 3400 CX with an 8200 CX AutoSampler modified for SPME Varian Star Workstation Version 4 and SPME software Injector 1077 Split splitless injector splitless mode 80 mL min vent flow 2 minute vent timing Temperature 220 C 7 m fiber and 250 C 100 m Therminol VP 1 is a heat transfer fluid that consists of fiber 73 5 Diphenyl oxide and 26 5 Biphenyl This material is widely used in the chemical process industry but must be kept out of t
15. is at the proper depth in the insert measure the distance in mm from the top of the injector nut to the end of the exposed fiber This is the injector penetration depth Use this value in Test SPME and other SPME methods Injector penetration depth 14 Figures 6A and 6B 6A shows the mark in the center of the fiber holder that was made during the desorption 6B shows the injector parts lined up so that the injector penetration depth can be observed Note You might want to make the first injection without a fiber assembly installed in the fiber holder After you have set the injection position and made an injection with a fiber installed verify that the fiber is intact after the injection Press F1 Menu and then F1 Change Syr to view the fiber Fiber depth in the sampling vial The default parameter for Vial Penetr in the TestSPME method is 22 mm This is the minimum depth that the fiber can be set to penetrate the vial Combi PAL 9 Protective needle Seal Magnetic steelcap 3 E S m E Fiber support rod 8 a amp SPME fiber gt Sl Figure 7 Showing the Vial Penetr parameter If the liquid phase is to be sampled the depth of the fiber in the vial and or the amount of liquid in the vial should be adjusted so that the fiber rod is above the meniscus of the liquid phase Sample volumes for various vials are suggested in the tabl
16. miscible very 9 1 v v very Table 1 Chemical and physical parameters of the target analytes Combi PAL 81 Instrumentation and Conditions Instrument Varian Star 3400 GC with an 8200CX AutoSampler modified for SPME SPME Il A Varian Star Workstation was used to run the AutoSampler and analyze the data Injector Isothermally held at 220 C for the length of the run Column SPB 5 30 m x 0 25 mm with a 1 um film thickness 30 C hold for 3 min ramp to 100 C at 15 C min total run time 7 7 min GC oven cool down 2 min total time 9 7 min Detector FID 10 300 C Automated SPME 85 um polyacrylate coating 10 min absorption no stirring 2 min desorption Conditions Headspace sampling over 0 5 mL liquid sample in 2 0 mL vials and over 5 0 mL liquid sample in 16 mL vials Sample Preparation small vials 2 5 g of NaCl was added to 10 mL of a 1000 ppm standard large vials 13 5g of NaCl was added to 50 mL of a 1000 ppm standard Standard Preparation A 2000 ppm standard containing the 5 target analytes from Table 1 was prepared in the following manner 2 mL of each component was pipetted into a 1000 mL volumetric flask Milli Q water was added to the flask to fill it to the mark A series of dilutions was performed to generate 1000 ppm 500 ppm 250 ppm 100 ppm and 10 ppm standards Experimental Criteria All experiments were performed using the Varian 8200CX AutoSampler with SPME Il The linearity of the method was
17. of compounds in the standard mix to drug samples spiked with the standard mix Standard Mix Drug A Drug B Conc LOD Compound pg mL Precision Corr pg mL Recovery Precision Recovery Precision Ethanol 100 9 2 47 Acetone 101 2 0 48 Isopropanol 101 7 0 60 Methylene chloride 91 5 2 15 Chloroform 76 6 1 25 Benzene 70 0 1 58 Trichloroethylene 63 4 2 00 1 4 Dioxane 104 2 0 44 Toluene 168 6 3 82 Blank runs of the drugs indicated that they were free of solvents with the exception of drug B which contained toluene Linearity and recoveries with drug A indicated no matrix effects therefore this drug was not studied further Combi PAL 37 Matrix effects With Drug B the polar solvents showed good linear response and recoveries but methylene chloride chloroform benzene and trichloroethylene were only partially recovered Toluene the solvent that was used in the purification of the drug was still present Moreover the toluene was strongly retained by the drug even after the dry compound was heated in an oven at 80 C for one hour Therefore it was felt that further study was warranted and a new toluene free sample of this compound was purchased When toluene was added to the toluene free drug the recovery was 29 The recovery experiment was repeated using conventional static headspace The data in Table 4 indicates that the matrix effect is present with heated headspace and is therefore not SPME related Table 4 Percentage r
18. of sample carryover Linearity According to the instructions the correlation coefficients to a straight line for each pesticide should have been 0 980 or better the actual values in this lab varied from 0 986 to 1 000 Accuracy The values of the pesticides in the unknown sample are listed in Table 1 along with the true values and the average of the values submitted by the other labs Pesticide Retention Quantitation True Values with Average Values of Time lon s Values Automated 11 Labs with minutes ppb System Manual SPME Dichlorvos 12 53 109 25 29 5 27 3 EPTC 15 15 128 10 10 3 9 9 Ethophos 21 41 158 17 18 4 15 5 Trifluralin 22 51 264 306 2 1 4 1 6 Simazine 24 01 201 25 29 5 23 6 Propazine 24 30 1724214 10 11 3 9 5 Diazinon 25 34 1374179 10 10 8 8 2 Methyl chlorpyriphos 27 23 286 2 2 4 1 6 Heptachlor 27 39 272 10 9 9 8 9 Aldrin 29 03 66 263 2 1 8 2 0 Metalochlor 29 13 1624238 17 19 8 15 7 Endrin 33 58 2814317 10 10 2 8 8 Table 1 Pesticides in the test sample The retention times quantitation ions and values mean of 3 determinations with the automated system are from the Varian applications laboratory The values with manual SPME are the means of the results submitted by the 11 participating laboratories 76 03 91483500 1 Note that the values listed in Table 1 for the 11 participating laboratories are averages not individual values When the correlations between the true values for each pesticide and the indi
19. of the headspace over a Muscat wine spiked with linalool The wine contained 150 ppb linalool before spiking The data showed linear responses indicating that neither fiber was saturated As expected the slopes of the linearity curves varied from sample to sample due to the different matrices Linearity and precision data are in Table 2 and Table 3 lists the quantities of the alcohols found in the wine samples and minimum detectable quantities Polyacrylate fiber rsd r slope rsd 1 26 0 995 1840 4 22 0 993 1255 4 73 0 995 2333 7 98 0 997 982 4 72 0 997 1228 6 71 0 996 503 5 36 0 996 1015 7 81 0 996 370 Table 2 Showing correlation coefficients to a straight line r after spiking 12 ethanol water and wine 1 with the terpene alcohols 0 150 ppb The slopes of the resulting curves are given because they are an indication of the matrix effect For example wine 1 contained 18 ethanol and recovery of the terpene alcohols was reduced as compared to the test sample n 6 amount present ppb mdq ppb S N 4 Wine1 Wine2 Wine3 ion trap FID linalool 150 0 2 1 6 citronellol 12 3 0 3 1 9 nerol 13 0 8 2 9 Combi PAL geraniol 32 2 1 0 4 0 Table 3 Quantities of each terpene alcohol identified in the wine samples and minimum detection levels mdq s 53 The mdq s were determined with a polyacrylate fiber with the 12 ethanol water mix These values vary slightly according to the sample matrix S
20. run under high temperature conditions prompted an evaluation of a 7 um bonded polydimethylsiloxane fiber The use of the thinner film bonded fiber allowed efficient desorption of the Therminol at a lower temperature 220 C and completely eliminated fiber bleed Peak Size 50000 4 ie 200007 25 50 75 Amount ppb Figure 2 Calibration curve for 1 to 100 ppb therminol in water 50 Figure 3 shows a comparison of the 100 um versus the 7 um fibers for a 10 ppb standard Peak areas with the 7 um fiber were about 3 times lower than the 100 um fiber However due to a sharper peak shape the peak heights and therefore minimum detection limits were approximately half 4 229 4 250 Figure 3 10 ppb Therminol in water 100 mm fiber left and 7 m fiber right Conclusions SPME is a simple sensitive highly effective approach to the automated analysis of Therminol in water Although a slightly lower detection limit is provided by the 100 um fiber the lower desorption temperature and bleed with potentially greater stability and lifetime provided by the 7um bonded phase fiber would make it the best choice for this analysis Acknowledgment The assistance of Maureen Good of Dupont Canada in the development of an automated SPME method for Therminol is greatly appreciated NOTE The 100 um fiber has been improved by Supelco and now has a temperature limit of 250 C 03 91483500 1 Characterizati
21. that SPME would be useful in other flavor applications In determining ppb levels of terpene alcohols in wines the main question was the ability of a SPME fiber to extract these compounds from various wine matrices which contained 8 20 ethanol The following study showed that indeed SPME is a practical technique for this application offering several advantages over SHS Instrumentation and Conditions Instruments Varian Saturn 3 GC MS with a septum equipped temperature programmable injector SPI FID and 8200 CX AutoSampler modified for SPME 3 A 486 DX PC was used to control the GC MS collect MS data and control the AutoSampler in the SPME mode The GC Star Workstation was used to collect FID data A Varian Genesis Headspace Sampler was used for comparative studies with static headspace Combi PAL 51 Column Injector Mass Spec FID Automated SPME Conditions Heated Headspace Samples SPME test plan Results and Discussion Sampling Conditions test samples at 2 ppm As expected ethanol in the sampling matrix reduced the amount of terpene alcohol extracted and salting out improved the recovery of the alcohols Figure 2 Table 1 compares headspace versus liquid recovery for the alcohols from the water ethanol matrix Figure 3 shows comparative responses with the 2 fibers at different sampling times It was decided to make a small sacrifice in sensitivity in favor of a simplified sample preparation proced
22. the composition of the samples Instrumentation and Conditions Instruments Column Injector Mass Spec Automated SPME Conditions Samples SPME Test Plan Combi PAL Varian Saturn 2000 MS MS interfaced to a Varian 3800 GC and automated SPME III system Varian VA 5MS 30 m x 0 25 mm 0 25 um film 50 C hold 3 minutes 15 minute to 80 C hold 1 minute 5 minute to 120 C hold 1 minute 20 minute to 280 C hold 1 minute total run time 24 minutes Carrier gas helium constant flow 1 mL minute 1079 split splitless injector with 0 8 mm SPME insert 250 C isothermal splitless mode for the first 3 minutes and split mode with split ratio 20 to the end of the thermal run Electron impact ionization mode ion trap temperature 150 C transfer line 220 C Full scan mode mass range 50 600 amu MS MS mode parent ion mass m z 94 mass isolation window m z 3 wave form type resonant excitation time 20 msec excitation amplitude 0 35 V mass range 65 69 amu Fiber Supelco Inc coated with 65 um Carbowax Divinylbenzene CW DVB SPME headspace 2 mL vial 10 minutes absorption 3 minutes desorption one sampling per vial No stirring was used Test sample consisting of standard phenol solutions water was used as solvent at various concentrations ranging from 1 ppt to 100 ppb Recycled paper samples about 60 mg in little fragments Determination of limit of detection LOD in full scan mode and with MS
23. volatile compound One consequence of the relatively uniform recovery with SPME is ease of optimization of instrument conditions 56 03 91483500 1 Library Search C NUAR IANNPOLSPME4 Acquired 22 Mar 1995 Scan number 1026 Comment TWO 100 clero 100 alpha Methylstyrene CAS 98 83 93 Hora He prepare epe 4 100 alpha Methylstyrene CAS 98 83 9 H A 100 alpha Methylstyrene CAS 98 83 9 F een ye gr my T T 100 110 120 130 140 Formula C9 H10 Rank 1 Index 3592 MolWeight 118 Search All LocalNorm On P ZEEMIF 946 R 959 CASH 98 83 9 Figure 2 Showing the results of the NIST92 Library search identifying peak 4 in the SPME chromatogram as a methylstyrene Quantitation Relative recovery after the various procedures described in the table under samples is shown in the graph Figure 3 The base most abundant ion for each compound was selected for peak integration Absolute quantitation is not possible in determining solvents given off by polymers The quantity of solvent in the headspace above the polymer varies with surface area temperature and sampling time Therefore precision would not be expected to be as good as with other SPME or SHS applications 2 Precision of response relative to methyl styrene varied from 3 10 relative standard deviation sample 1 4 replicates To obtain some idea of the actual mass of solvents in the vial the analyst co
24. was not the case with the polyacrylate fiber Figure 3 For this application the PDMS fiber provided better sensitivity and a shorter equilibrium time than the polyacrylate fiber However the polyacrylate fiber has been shown to be useful for determination of phenols 4 Combi PAL Comparison with Headspace The test sample and the beverage were analyzed using static headspace and SPME with a PDMS fiber The comparative responses of the compounds in the test sample are shown in Figure 4 Table 2 lists precision data for 10 replicates when the critical compounds in the fruit beverage were monitored by headspace and SPME 47 Table 2 Precision of SPME and static headspace Table 3 Minimum detectable quantities with FID and MS sampling of components in a fruit beverage FID area detection in ppb The data is from SPME headspace counts RSD n 10 A 100 um PDMS fiber was used sampling of the test mix using a 100 um PDMS fiber Compound SPME S Compound FiD s nm 4 MS s n 10 Ethylacetate 139 369 Ethylacetate 26 28 Ethyl butyrate 1 42 4 46 Ethyl butyrate 1 3 0 4 Ethyl isovalerate 2 95 4 83 Ethyl isovalerate 0 6 0 3 Isoamyl acetate 3 42 4 58 Isoamyl acetate 0 6 0 1 Ethyl valerate 1 54 4 53 Ethyl valerate 1 0 0 04 Limonene 2 96 7 03 Limonene 0 2 0 07 Benzaldehyde 1 28 8 34 Benzaldehyde 0 2 0 02 The minimum detectable quantities of the components in the test mix are in Table 3 3 0 EE SPME respon
25. water 1 The Varian Star system provides a high efficiency cryofocusing inlet system with a 100 000 C sec desorb ramp rate virtually eliminating band broadening and allowing the use of short conventional 0 25mm columns In conjunction an automated 8200 CX SPME II system including software control via the Star Workstation makes sample preparation fast and easy 0 244 0 493 0 204 262 With SPME analytes in the liquid sample or in the headspace above it are absorbed onto fused silica fibers coated with a polymer such as E polydimethylsiloxane The fiber is then inserted into a E GC injector for desorption The system has been E bis Figure 2 SPME headspace igure 1 eadspace s automated with the Varian 8200 AutoSampler The Sa ppm BTEX in sampling of 1 ppb BTEX in very rapid equilibration of non polar volatile analytes water PID water PID in the headspace approximately 70 equilibrated during the first minute allows for very short absorption times This makes headspace SPME very compatible with FastGC Using these two techniques combined resulted in a total of a 4 minute sample cycle time including data processing This allows the analysis of 48 samples in a little over 3 hours the only sample preparation being the filling of the vials Benzene Toluene Xylenes The exact instrument and SPME conditions used are listed below In essence the chromatography was carried out w
26. 0 C FID at range 10 Detectors a SPME The fiber Supelco Inc was coated with 100 um polydimethylsiloxane Parameters Adsorbed in the headspace 14 minutes desorbed two minutes one sampling per vial A test standard was prepared in HPLC water Table 3 The first three compounds Standards were added directly to water the last 6 compounds were initially dissolved in a methanol stock solution and diluted 1000 fold in water Two water soluble drugs were studied a cholinesterase inhibitor A and a Samples tricyclic antidepressant B Three samples were prepared in two mL screw cap vials the above test sample Recovery alone drug A in test mix and drug B in test mix To conform to the concentrations Accuracy listed in the USP methods of 20 mg mL 16 mg of drug was dissolved in 0 8 mL of test sample Blanks consisting of water and each of the two drugs in water were also prepared To enhance the response of the polar solvents the standards and samples were saturated with sodium sulfate 20g 100g water 5 N The above standard was prepared at 0 5 and 2 times the concentrations shown Linearity in the table and the recovery experiment above was repeated at the three concentrations Limits of detection LOD s were determined assuming a signal to noise ratio of 2 03 9147835 00 1 Results and Discussion en The chromatogram in Figure 1 was obtained from 3 Acetone 25 i 3 4 Isopropanol 25 sampling the headspace over D
27. 0 1 Troubleshooting Symptom Fiber breaks in injector Possible Cause Improper depth in injector Recommended Action Verify see above that the bottom of the SPME fiber syringe is not less than 5 mm into the insert Fiber breaks in injector Septum corings or other particles are in the injector Replace insert If septum particles are present consider using a seal such as the Merlin Microseal to eliminate the septum Poor precision Vials are leaking Verify that the cap cannot be turned after sealing Reduce the extraction temperature to see if the precision improves Temperatures gt 80 are not recommended Poor precision Poor sample handling See the Advantage Note on SPME method development in the SPME Application and Advantage Note section of this manual Sample carryover Fiber is not fully desorbed Increase desorption time and or temperature or bake out the fiber after each injection Sample carryover Fiber support rod is submerged in liquid sample Reduce fiber penetration depth in vial or reduce amount of sample in the vial Extraneous peaks in blanks Contamination is in the GC Verify that the GC is clean by making a run without injecting Extraneous peaks in blanks Combi PAL Contamination is in the sample vial septa Sample an empty vial without a septum installed Sample an empty vial with a septum installed If the contamination i
28. 01 ANAL CHEM VOL 67 15 PP 2530 3 ANAL COMMUN 33 12 PP 421 424 J High Resol Chromatogr Vol 19 pp257 262 ANAL CHEM 68 1 PP 130 3 J Am Soc Mass Spectrom 1995 VOL 6 1 PP 1119 30 J Chromatogr A Vol 776 2 pp293 303 Anal Chem Vol 69 16 p p3140 3147 J HIGH RESOL CHROMATOGR VOL 18 PP 625 629 J HIGH RESOL CHROMATOGR VOL 18 PP 161 166 ANAL CHEM VOL 67 18 PP 3265 74 ANAL CHEM 69 4 PP 587 596 ANAL COMMUN 1996 33 10 PP 361 364 Techniques for Analyzing Food Aroma edited by Marsali Marcel Dekker NY pp 81 112 J CHROMATOGR VOL 603 P 185 J CHROMATOGR A VOL 678 2 PP 313 18 Jpn J Forensic Toxicol Vol 13 3 pp 189 194 03 914835 00 1 AUTHOR S Jinno K Muramatsu T Saito Y Kiso Y Magdic S Pawliszyn J Johansen S Pawliszyn J Kumazawa T Lee X Sato K Seno H Ishii A Suzuki O Kumazawa T Lee X Tsai M Seno H Ishii A Sato K Kumazawa T Watanabe K Sato K Seno H Ishii A Suzuki O LANGENFELD J J HAWTHORNE S B MILLER D J Lee X P Kumazawa T Sato K Suzuki O Lopez Avila V Young R Lord H L Pawliszyn J Macgillivray B Pawliszyn J Fowlie P Sagara C Magdic S Boyd Boland A Jinno K Pawliszyn J Magdic S Pawliszyn J Martos P A Pawliszyn J Martos Perry A Pawliszyn J
29. 19 087 i 18 dinoseb 19 531 ILL lore WE Figure 2 SPME chromatograms of the phenol test mixture at 50 ppb with and without agitation The absorption time for the polyacrylate fiber was 20 minutes and desorption time was 3 minutes 72 03 91483500 1 The relative effectiveness of agitation for compounds of different volatilities is shown in more detail in Figure 3 where the responses of two phenols with different boiling points are compared HB with agitation E without agitation pentachlorophenol BP 310 C 2 chlorophenol BP 175 C Absorption time minutes Figure 3 Details of the effect of agitating the fiber during SPME sampling for various times on the response of two phenols of different volatilities The bars represent detector response after SPME sampling the of the phenol mixture at 100 ppb Agitating the fiber always increased the response but the effect was greater for pentachlorophenol the less volatile compound The precision of replicate analyses is shown in Table 1 To examine linearity the mix was sampled at concentrations of 0 10 50 100 and 200 ppb Correlation to a straight line varied from 0 991 to greater than 0 999 for the phenols in the mix Compound mdq rsd ppb n 6 phenol 1 40 1 52 2 chlorophenol 0 32 2 69 2 methylphenol 0 34 2 16 3 methylphenol 0 62 2 32 4 methylphenol 2 nitrophenol 0 56 5 26 2 4 dimethylphenol 0 20 3 61 2 4 dichlorophenol 0 17 6 11 2 6 dichlorophenol
30. 4 SPME fiber DVB PDMS StableFlex Auto 70um pk 3 SU57327U SPME fiber Carboxen PDMS Auto 75um pk 3 03 918963 16 SPME fiber Carboxen PDMS StableFlex Auto 85um pk 3 SU57335U SPME fiber Carboxen DVB PDMS StableFlex Auto 80um pk 3 SU57329U SPME fiber Carboxen DVB PDMS StableFlex 2cm Auto 80um pk 3 SU57348U Inserts for non Varian injectors can be ordered from Supelco 5 Other SPME phases with a 23 gauge protective needle must be ordered from Supelco Combi PAL 18 03 914835 00 1 SPME References Useful Web pages Supelco Varian University of Texas SPME bibliography Books http www sigma aldrich com SAWS nsf Pages Supelco EditDocument http www varianinc com csb gcnotes spmeindex html http www cm utexas edu brodbelt some_refs html 1 Pawliszyn J Solid Phase Microextraction Theory and Practice Wiley VCH Inc New York 1997 2 Wercinski S ed Solid Phase Microextraction a Practical Guide Marcel Dekker New York in press Journal Articles and Book Chapters AUTHOR S YEAR TITLE REFERENCE Ai Jui 1997 Headspace Solid Phase Microextraction Dynamics Anal Chem Vol 69 16 PP 3260 and Quantitative Analysis before Reaching a 3266 Partition Equilibrium Ameno K Fuke C 1996 Application Of A Solid Phase Microextraction Can Soc Forensic Sci 29 2 43 48 Ameno S Kinoshita H Technique For The Detection Of Urinary Ijiri 1 Methamphetamine And
31. A ce A Ba dl chardonnay 20 La L 2 4 6 8 10 12 14 16 18 Retention Time minutes ECD FID 2 4 6 8 10 12 14 16 18 Retention Time minutes 20 Ml h ad 4 6 8 10 12 14 Retention Time minutes A 16 18 20 D 4 6 8 10 12 14 Retention Time minutes 16 18 20 Figure 1 SPME Chromatograms of the headspace over food samples The flame onization detector was at range 10 12 for all of the chromatograms but the attenuation was adjusted to keep the larger peaks close to full scale Detector attenuation was the same for the three alcoholic beverages on the first chromatogram The samples are A alcoholic beverages B orange juice C ground coffee beans and D chamomile tea leaves SPME offers sensitivity at the ppb level In addition there are several advantages over competing techniques such as static headspace purge and trap and thermal desorption These include no exposure of the analytes to active sites in transfer lines or collection tubes relatively inexpensive instrumentation with full automation and no additional requirements for bench space 34 03 9147835 00 1 Determination of Residual Solvents in Pharmaceuticals with Automated Solid Phase Microextraction Zelda Penton Varian Chromatography Systems SPME Varian Application Note Number 2 Key Words Solid phase microextraction SPME 8200 AutoSampler pharmac
32. Amphetamine By Gas Chromatography Arthur C L Buchholz K 1993 Theoretical And Practical Aspects Of Solid Phase Natl Meet Am Chem Soc Div D Potter D W Zhang Microextraction With Thermal Desorption Using Environ Chem vol 33 1 pp 424 427 Z Pawliszyn J Coated Fused Silica Fibers Arthur C L Potter D W 1992 Solid Phase Microextraction For The Direct Analysis LC GC VOL 10 9 PP 656 658 660 Buchholz K D Motlagh Of Water Theory And Practice 1 S Pawliszyn J Arthur C L Buchholz K 1993 Practical And Theoretical Aspects Of Solid Phase PROC WATER QUAL TECHNOL D Potter D W Motlagh Microextraction For The Direct Analysis Of CONF PT 2 PP 1315 33 S Killam l Pawliszyn J Groundwater Arthur C L Killam M 1992 Analysis Of Substituted Benzene Compounds In ENVIRON SCI TECHNOL VOL 26 Motlagh S Lim M Potter Groundwater Using Solid Phase Microextraction 5 PP 979 983 D W Pawliszyn J Arthur C L Pawliszyn J 1990 Solid Phase Microextraction With Thermal ANAL CHEM VOL 62 19 PP 2145 8 Desorption Using Fused Silica Optical Fibers Arthur C L Killam L M 1992 Automation And Optimization Of Solid Phase ANAL CHEM VOL 64 17 PP 1960 Buchholz K D Pawliszyn Microextraction 6 J Berg J R Barshick S A Griest W 1998 Trace Analysis of Explosives in Seawater Using Anal Chem 70 pp 3015 3020 H Solid Phase Microextraction and Gas Chromatography lon Trap Mass Sp
33. CE As with all techniques some initial method development is required to optimize results Acknowledgment Samples and valuable inputs on the requirements of pharmaceutical manufacturers were provided by Stephen Scypinski Linda Clark Nelson Sandra Rosen Shaw and Anne Marie Smith of Hoffmann La Roche Inc Nutley NJ Their assistance is gratefully acknowledged References and Additional Reading 1 The 1995 United States Pharmacopeia National Formulary USP 23 NF18 published by the United States Pharmacopeial Convention Inc 12601 Twinbrook Parkway Rockville MD 20852 2 Z Zhang and J Pawliszyn Headspace Solid Phase Microextration Analytical Chemistry 1993 Vol 65 No 14 1843 1852 03 91483500 1 Determination of a Wide Range of Organic Impurities in Water with Automated Solid Phase Microextraction Zelda Penton Varian Chromatography Systems SPME Varian Application Note Number 3 Key Words Solid phase Microextraction SPME 8200 AutoSampler Volatiles Semivolatiles While gas chromatography is the instrument of choice in the determination of organic compounds in water several methods are available for introducing the sample into the GC column A comparison of several methods was undertaken to assess the relative merits of each technique These were direct aqueous injection ambient and heated static headspace Precision and minimum detectable quantities were compared As SPME is a relatively
34. DMS fiber Sampling time 20 minutes E 10 minutes E 20 minutes 30 minutes Detector Response PDMS Polyacrylate Figure 3 Comparison of FID response to linalool 2 ppm in water after sampling the headspace with two SPME fibers for different times Identification of Alcohols and Quantitation The terpene alcohols in the wine samples were identified by comparison with pure standards and with the NIST92 library in the Saturn software The ions used for quantitation were 71 93 linalool 67 95 citronellol 67 69 nerol and geraniol For further identification chemical ionization was also used With acetonitrile the mass of the main ion indicated that all of the alcohols lost water with the exception of citronellol The three wines and a blank 12 5 ethanol water mix were spiked with terpene alcohol standards over the range of 0 150 ppb and linearity was confirmed PDMS fiber r slope linalool test mix 0 998 949 wine 1 0 997 686 citronellol test mix 0 998 1269 wine 1 1 000 675 nerol test mix 0 999 586 wine 1 0 999 315 geraniol test mix 0 997 528 wine 1 0 999 266 with both the polyacrylate and PDMS fibers by sampling the headspace over these samples Figure 4 shows the linearity curve for linalool in the Australian Muscat wine 2 00E 05 1 50E 05 1 00E 05 Response mass 71 93 5 00E 04 0 00E 00 0 50 100 150 Amount spiked ppb Figure 4 lon trap response after SPME sampling
35. MS Semi quantitative determination of phenol in the real samples 97 Results and Discussion LOD in Full Scan Mode The LOD in full scan mode was determined by exposing the SPME fiber to 1 ul of a water solution containing 100 pg of phenol Under those conditions the entire sample evaporated and there was only one phase in the vial When ion 94 was plotted the signal to noise ratio of phenol was 28 Figure 1 LOD in MS MS Mode Using the MS MS feature of the Varian Saturn the LOD was reduced to 10 pg Fig 2 The molecular ion at m z 94 was isolated and the ions from 65 69 were plotted The total ion chromatogram showed a S N of 6 Figure 2 the plot of the daughter ion 66 amu showed a S N 12 Recycled Paper Samples In the analysis of real samples we found phenol concentrations in the range 150 500 ppt Quantitation was performed by spiking the samples with 100 pg of phenol and by comparison of the peak areas before and after spiking Conclusions The technique presented here is extremely rapid very reliable and very sensitive The methods now in use are quite tedious For instance the I R S A Italian Research Institute on Water a spectrophotometric method is not suitable for solid matrices It requires that the phenol be extracted from the paper and dissolved in water Furthermore the LOD is 5 ppb as opposed to 150 ppt with SPME and GC MS MS 98 Counts minutes Fi
36. Phase Microextraction and Gas Chromatography with Thermionic Selective Detection Method Optimization for the Analysis of Amphetamines in Urine by Solid Phase Microextraction Headspace Solid Phase Microextraction Versus Purge And Trap For The Determination Of Substituted Benzene Compounds In Water Analysis Of Organophosphorus Insecticides From Environmental Samples Using Solid Phase Microextraction Analysis Of Organochlorine Pesticides Using Solid Phase Microextraction Calibration of Solid Phase Microextraction for Air Analyses Based on Physical Chemical Properties of the Coating Sampling and Determination of Formaldehyde Using Solid Phase Microextraction with On Fiber Derivatization Estimation of air coating distribution coefficients for solid phase microextraction using retention indexes from linear temperature programmed capillary gas chromatography Application to the sampling and analysis of total petroleum hydrocarbons in air Recent Advances In Solid Phase Microextraction For Environmental Samples Characterization of water soluble components of slurries using solid phase microextraction coupled to liquid chromatography mass spectrometry On Line Monitoring of Flowing Samples Using Solid Phase Microextraction Gas Chromatography An Evaluation Of Solid Phase Microextraction For Analysis Of Volatile Organic Compounds In Drinking Water Extraction Of Low Level Chlorinated Pesticides Using Solid Phase Microextraction
37. The sample time was 30 minutes to increase the probability that equilibrium was attained It is likely that a shorter sampling time could have been used but time and sample limitations prevented a detailed study to determine the minimum extraction time Combi PAL 95 96 03 91483500 1 Determination of Phenol Content in Fibers of S P M E Industrial Interest Varian Application Note Number 18 Sergio PUCCI Alessandro SABA Andrea RAFFAELLI and Piero SALVADORI Dipartimento di Chimica e Chimica Industriale Universit di Pisa Centro di Studio del CNR per le Macromolecole Stereordinate ed Otticamente Attive Via Risorgimento 35 56126 Pisa Italy Varian CSB Contact Zelda Penton Key Words SPME Saturn Phenols Phenol CAS 108 95 7 is a highly toxic organic compound Its presence inside a working location with a concentration higher than 20 mg m can be detrimental to health NIOSH TWA recommendations based on up to a 10 h exposure 1978 A simple and rapid analytical method capable of determining phenol in fibers of industrial interest with high sensitivity can be very important We developed a GC MS method using SPME for analyte extraction and enrichment This method was tested on paper samples of different nature and origin including samples of recycled paper and it proved to be very reliable and sensitive A major advantage of SPME for this application is that sample pre treatment is minimal thus avoiding any alteration of
38. acrylate Liquid sampling for various times ranging from 5 60 minutes 3 minutes desorption one sampling per vial Sampling was with and without agitation for comparison A one mL volume of liquid sample in a 2 0 mL vial was found to give the best precision when agitating the fiber A test sample Supelco containing 18 phenols in isopropanol at a concentration of 2 mg mL each compound was diluted in HPLC grade water to concentrations of 10 50 100 and 200ppb The water was adjusted to pH 2 with HCI and saturated with Na2SO4 Experimental Procedure and Results The chromatogram in Figure 2 shows chromatograms of the compounds in the test sample with and without agitation Note the significant enhancement in response with agitation particularly at the end of the chromatogram where the less volatile phenols were eluted Compound R T 10 1 phenol 9 069 8 11 with agitation 2 2 chlorophenol 9 194 7 9 3 2 methylphenol 10 300 4 3 methylphenol 10 626 12 5 4 methylphenol 10 626 6 2 nitrophenol 11 530 2 4 5 7 2 4 dimethylphenol 11 729 3 15 8 2 4 dichlorophenol 12 074 6 9 2 6 dichlorophenol 12 564 17 18 10 4 chloro 3 13 664 14 16 methylphenol 1 13 11 2 4 5 trichlorophenol 14 553 12 2 4 6 trichlorophenol 14 639 13 2 4 dinitrophenol 16 348 14 4 nitrophenol 16 480 without agitation 15 2 3 4 6 16 946 tetrachlorophenol 16 2 methyl 4 6 17 523 dinitrophenol 17 pentachlorophenol
39. additional guidelines should be followed 5 When preparing standards of volatiles in water the liquid should fill the entire storage container without any headspace 6 Losses can occur when diluting the high level standard in preparation for a linearity study To minimize errors fill the containers that are to contain diluted standards with cold water at the correct volume for the dilution quickly pour the concentrated standard into the containers cap mix and refrigerate For example when diluting to 1 2 and 1 4 the concentration of the highest standard take 40 mL vials 44 mL when filled to the top add 22 mL and 33 mL of cold water then pour in the concentrated standard 7 If salt is added or the pH is adjusted great care should be taken to minimize losses For example if the samples and standards are to be diluted in water the salt can be added to the water before the dilution is made 8 Chill the AutoSampler vials before adding the samples Remove the standards and samples from the refrigerator uncap them and quickly transfer aliquots to the AutoSampler vials using a pipette that easily fits into the neck of the vial 9 Cap the AutoSampler vials quickly If solids were placed in the vial prior to adding the liquid mixing the vortex mixer will assure a homogeneous ample Aqueous standards and samples remaining in the storage containers that were used to fill the AutoSampler vials should not be used again Just before analy
40. aks bake the septa in a GC oven at 150 C overnight and store in a clean container not plastic Unbaked septum Seo 7 WA a PO E uhr Mi A ee ds e 5 Baked septum u En i si he AA A ti Ml Figure 1 SPME chromatogram 100 um PDMS fiber of an empty vial with a baked and unbaked septum FID detector Combi PAL 27 Oo o co The injector insert should have an internal diameter of 0 75 0 80 mm If possible use a Merlin Microseal or other seal to avoid using a septum in the injector Note that the Merlin Microseal requires SPME fibers with 23 gauge needles For quantitative work the fiber should be changed after approximately 100 runs With water soluble analytes saturating the sample with salt usually sodium chloride or sodium sulfate can enhance sensitivity Standards and samples are normally prepared and diluted in storage containers and then transferred to AutoSampler vials for analysis Prepare samples and standards carefully so that volatiles are not lost a After preparation water samples containing volatiles should completely fill the storage container without any headspace b Store samples in the refrigerator Chill the AutoSampler vials before adding the sample c Transfer samples to the AutoSampler vials with a pipette of sufficient capacity to deliver the entire sample in one step The outer diameter of the pipette should be small enough to allow the pipette to easily fit into the Aut
41. ampler was used for comparative studies with static headspace Column 30m x 0 25 mm coated with 0 5 um Supelcowax 40 C hold 2 minutes 10 minute to 180 C 30 minute to 220 C hold 3 67 minutes total run time 21 minutes Carrier gas helium at 41 cm s at 50 C Injector SPI with SPME insert 220 C isothermal Mass Spec Electron impact ionization mode mass range 40 250 m z FID 230 C range 10 Automated The fibers Supelco Inc were coated with 100 um polydimethylsiloxane PDMS and 85 um SPME polyacrylate Conditions Sampled the headspace over an 0 8 mL liquid sample in a 2 mL vial Normally 20 minutes adsorption two minutes desorption one sampling per vial 5 60 minutes adsorption in the equilibration study Heated Samples 10 mL in a 22 mL vial were heated to 75 C line and valve temperatures were Headspace 85 C Equilibration time 5 minutes mixed at 80 of full power 7 minutes stabilization time 2 minutes Sample loop was 500 uL Samples Commercially available fruit beverage Figure 1 is a SPME chromatogram of the fruit beverage using a PDMS fiber Test sample consisting of components identified in above beverage dissolved in HPLC water Table 1 le nt ae Table 1 Components of the test sample These 3 Ethyl isovalerate compounds were identified in the fruit beverage by 4 Isoamyl acetate GC MS 5 Ethyl valerate AAA 6 Limonene Compound Conc ppb 7 Be
42. atility The hardware a modified Varian 8200 AutoSampler can be used for either direct liquid injection or SPME furthermore it is installed on top of the GC thus conserving laboratory bench space ethanol n propanol 0 76 min 1 48 min Figure 1 SPME chromatogram of ethanol 186 mg dL in blood from a California driver Combi PAL 63 Instrumentation and Conditions Instruments Varian Star 3400 GC with a septum equipped temperature programmable injector SPI FID and 8200 CX AutoSampler modified for SPME The Star Workstation controlled the GC and AutoSampler and acquired data The Advanced Applications for Excel were used to generate summary reports A Varian Genesis Headspace Sampler with e form option was used for comparative studies with static headspace Column 15 m x 0 53 mm coated with 1 um DB Wax 40 C 4 minutes Carrier gas helium Injector SPI with SPME insert at 210 C isothermal The carrier gas inlet of the SPI was connected to the Headspace Sampler Detector FID at range 10 220 C Automated Fibers Supelco Inc were coated with 65 um Carbowax divinylbenzene SPME Headspace sampling 3 minutes absorption 1 minute desorption one sampling per vial Figure 1 is Conditions a SPME chromatogram Heated Samples were heated to 40 C valve and transfer line temperatures were 80 C Equilibration time Headspace was 30 minutes Sample loop was 1 mL Experimental Procedure and Resul
43. ation was used to control the instruments and collect data 15 m x 0 53 mm coated with 1 um DB Wax Column oven 40 C hold 3 minutes Carrier gas helium 28 mL min splitter flow 67 mL min Injector 1078 with 0 8 mm insert 210 C isothermal Relay program time 0 relay open close at 01 minutes open at 3 minutes Detector FID at 220 C range 10 Fibers Supelco Inc were coated with 65 um Carbowax divinyl benzene absorbed 3 minutes headspace desorbed 1 minute one sampling per vial total run time 4 min The sample was decanted into 24 mL plastic vials and spiked with 10 uL of methanol standards at concentrations from zero to pure methanol Final concentrations were 0 67 2 168 and 336 ppm w v plus the amount in the original sample The samples 600 uL were placed in 2 mL vials using a displacement pipette It was very important to use this type of pipette for this extremely viscous sample and also to wipe off the outside of the pipette to assure that the corrosive mixture was deposited only at the bottom of the vial where it would not contact the fiber To minimize extraneous peaks the vial septa were baked at 150 C overnight Results and Discussion Figure 1 is achromatogram of the unspiked sample The calibration curve is shown below Figure 2 40000 y 56 806x 22280 R 0 9971 ppm methanol w v Figure 2 Showing the standard additions calibration curve for spiked caustic sam
44. ave TAY Varian Analytical Instruments 2700 Mitchell Drive Walnut Creek CA 94598 1675 USA Combi PAL SPME Manual Supplement to the Combi PAL System Users Manual OVarian Inc 1999 Printed in the U S A 03 914835 00 1 Table of Contents INTrOQUCHON ins NAAA AN A ds 3 Procedure for SPME Sampling with the Combi PAL ooooocononnccnccccccccncnnnnnnnnnnnccnnnnnnnnnnanccnnnnennns 4 Troublesh60U1G 2 22 2322 A A A a aaa 15 SUP DNS ud dd 17 SPME References 1 A ab 19 Combi PAL 1 03 914835 00 1 Introduction The Combi PAL SPME option offers the analyst several features that will enhance the utility of this exciting sample preparation technique These include 1 Choice of 2 10 or 20 mL vials 2 Large number of samples Standard configuration is two trays with 98 2 mL vials per tray or 32 10 20 mL vials per tray Up to two additional trays can be added if necessary Shaking and heating the sample during the extraction process Constant heating time for each sample The fiber can be automatically conditioned before a series of runs or after the desorption step in each run with an optional heating accessory User selectable sampling and injection depths Automatic method development by using sequential methods with different parameters incrementally increasing extraction times or extraction temperatures for example This manual covers the operation of the Combi PAL in the SPME mode with the basic software
45. be linear over the range tested from 10 ppm to 2000 ppm with the GC FID 82 03 91483500 1 Conclusions The determination of alcohols using the SPME AutoSampler with headspace sampling was proven to be successful The extraction of alcohols from aqueous media was performed using an 85 um polyacrylate coating Automation reduces the time required by the analyst for sample preparation and analysis as compared to manual extraction References Zhang Z Yang M Pawliszyn J Anal Chem 1994 66 844A Pawliszyn J TRAC 1995 14 3 113 Zhang Z Pawliszyn J J High Resol Chromatogr 1993 16 689 Zhang Z Pawliszyn J Anal Chem 1993 65 1843 Shirey R Mani V Butler M The Reporter vol 14 no 5 1995 Penton Z Varian SPME Application Note No 8 1995 Penton Z Varian SPME Application Note No 9 1995 NX DRAGON Combi PAL 83 84 03 91483500 1 Determining Volatiles in Beer with Automated S P M E SPME and GC MS ECD Varian Application Note Number 15 Zelda Penton Varian Chromatography Systems Key Words SPME 8200CX Food Saturn Volatile compounds are monitored in beer to detect components causing off flavors as well as to assure uniformity of product Compounds of particular interest are 2 3 butanedione diacetyl 2 3 pentanedione trans 2 nonenal trans trans 2 4 decadienal and ethyl esters Figure 1 Solid phase microextraction SPME was evaluated for determining th
46. been designated as FiberExp From the Job Queue page enter the following sequence Menu Luu setup L Objects Vials FiberExp Assuming the agitator is installed on the right side set the x y and z parameters so that the right edge of the injection unit is resting on the left rear edge of the agitator Figure 3 If the agitator is on the left side then the left edge of the injector unit should rest on the right rear edge of the agitator Press F4 Home Figure 3 Injection unit in the FiberExp position with the right edge just touching the left rear edge of the agitator 6 03 914835 00 1 Plunger crosspiece y Scale 36mm iD 24 E E 5 5 i assembly Fiber 10mm Scale 36mm ID 24 Figure 4 Left injector unit with plunger holder installed A The arrows marked B are pointing to the upper and lower needle guides Center unassembled parts Right fiber holder and fiber assembly installed in the SPME adapter Installation of the SPME adapter 1 Press F1 Menu and then F1 Chang Syr The injection unit will move to a position that will facilitate installation of the SPME adapter 2 If the injection unit is directly over a sample tray the Chang Syr position should be changed 3 Press Continue and then Utilities Syringe 4 Press F3 Set Pos and set the x y z positions to a location where there is a clear space under the fiber Then Press
47. d in a mixture with several other organic compounds in water top 3 rows All ofthe compounds were at the concentration shown at left except chloroform which was at half the concentration shown These data were obtained by SPME fiber sampling of the liquid phase with a 100 um PDMS fiber 1 2 4 trimethylbenzene Is it better to sample the liquid or the headspace Theoretically the response should be the same if the volumes sampled are similar This has been found to be the case for the compounds listed in Table 1 Practically for compounds of very low volatility the extraction time from the headspace is long and liquid sampling is preferable Does the fiber pick up contaminants in the air that will interfere with the analysis After a fiber that has been conditioned the first run each day should be a blank Ghost peaks often appear from AutoSampler vial septa see above If this occurs the user should bake the septa in a lab oven at 150 C before use In order to minimize the presence of extraneous peaks the SPME software parameters should be set so that the GC is ready for the sample to be injected immediately after extraction See the manual for a detailed explanation What are the benefits of heating during SPME extraction The effect of heating depends on both the compound and the fiber but generally volatile compounds show an increased response upon heating to 40 45 C Above these temperatures the response goes down due to migrati
48. d to SPME With multiple extraction a polymer is sealed in a vial and sampled repeatedly at equal time intervals It is assumed that the concentration of volatiles Multiple extraction can also be applied to aqueous samples if the partition coefficient between water and the analyte is small the analyte must favor the headspace and a substantial quantity must be removed at each extraction under these conditions will decay exponentially Figure 1 If an infinite number of extractions are carried out the volatiles will be completely removed from the vial The total area count of the analyte is equal to the sum of the areas from each individual extraction A In this note vinyl chloride monomer was determined in a finely ground sample of polyvinyl chloride material A carboxen PDMS fiber was used for sampling Figure 1 Showing 4 successive extractions of vinyl chloride from a polymer with a Carboxen PDMS fiber and FID detection The retention time was 1 03 minutes Instrumentation and Conditions Instruments Varian 3800 GC equipped with FID and a 1079 injector Automated SPME lll system Varian Star Workstation to control the GC and SPME AutoSampler and to collect data Column Injector EFC FID Automated SPME Conditions Samples Standards 30 m x 0 53 mm coated with 3 um DB 624 temperature program 60 C 5 minutes 20 C min to 200 hold 10 min 1079 isothermal splitless mode with SPME in
49. d to the true values 502 A 4 7 gg 12 Dichlorvos EPTC Ethophos Trifluralin Simazine Propazine Diazinon Methyl chlorpyriphos Heptachlor 10 Aldrin 11 Metalochlor 12 Endrin T 9848 1288 1598 1898 14 99 19 99 24 99 29 99 OCOONOOARWN gt 1721 4 6 san 1668 1268 1484 1688 13 33 16 66 19 99 23 33 26 66 Figure 1 Total ion chromatogram of the test sample at 30 ppb A The pesticides with relatively low responses can be seen in the selected ion chromatograms B Combi PAL 75 Instrumentation and Conditions Instrument Varian Saturn 2000 GCMS equipped with an automated SPME III system Column 30 m x 0 25 mm coated with 0 25 um SPB 5 40 C 5 minutes 30 C min to 100 5 Ymin to 250 50 min to 300 C hold one minute Carrier gas helium at 41 cm s at 60 C Injector 1078 with SPME insert at 250 C isothermal lon trap Electron impact ionization mode mass range 50 400 m z ion trap temperature 200 C Automated Fibers Supelco Inc were coated with 100 um Polydimethylsiloxane SPME Liquid sampling with agitation 45 minutes absorption 5 minutes desorption one sampling per vial Conditions One mL sample in 2 mL vials Samples Two pesticide samples were provided the first was a standard with 12 pesticides Table 1 at known concentrations the second contained the same pesticides at unknown concentrati
50. dy Number 12 Zelda Penton Varian Chromatography Systems Key Words SPME 8200CX Pesticides Saturn Solid phase microextraction SPME is a rapidly growing sample preparation method used most frequently for extracting trace organics in aqueous matrices prior to injection into a GC One measure of the validity of a new analytical method is to determine if several different laboratories will agree closely with each other and with the true value when analyzing an unknown sample Therefore an interlaboratory study 1 was conducted by G recki Mindrup and Pawliszyn to determine if manual SPME combined with GCMS is a useful technique for the determination of trace pesticides in water A detailed experimental protocol was provided to 11 participating laboratories and all of the participating laboratories received a fused silica column SPME fibers and samples from Supelco Inc The protocol specified SPME extraction of 25 mL pesticide samples in 40 mL vials with magnetic stirring This laboratory was not one of the participants in the test However a kit with the same column SPME fibers and test sample was used to collect data for comparison of results with the 11 laboratories The specified procedure was followed but the automated SPME Ill system with agitation was used with 1 mL samples in 2 mL vials It will be shown below that the automated system with small vials produced results very close to the mean of the other laboratories an
51. e 10 Volume of Sample mL Vial Volume Headspace sampling Liquid sampling 2 mL 0 6 1 3 10 mL 6 0 9 0 20 mL 15 0 18 0 03 914835 00 1 Optional bakeout of the fiber after injection With some fibers a high temperature is necessary to desorb the analytes completely Often the GC injector cannot be set to a high enough temperature because a column with a low temperature limit is installed With the Combi PAL the user can bake the fiber after desorption in a separate bakeout station Figure 8 This is an optional piece of hardware LANA an Figure 8 Optional bakeout stati Ch on The baking occurs with a flow of inert purge gas To enable this feature install the bakeout station Then define the position of the bakeout station NdlHeater as follows Menu gt F Utilities 7 Injector D j NdlHeatr Set the x y z parameters The temperature can be set in increments of 5 C from 30 to 350 C To set the temperature Press Menu Setup 3 gt Objects D Injectors NdiHeatr Combi PAL 11 Building a SPME method See the Combi PAL System User Manual for details on how to build a method The parameters in the SPME method are discussed below PARAMETER VALUE COMMENTS Cycle SPME Syringe Fiber Pre Inc Time 00 00 00 23 59 59 Allows the sample to be preheated prior to insertion of the fiber Incubat Temp 30 0 C 200 C
52. e 11 3 Optimization of Solid Phase Microextraction Conditions for Determination of Phenols Buchholz K D and Pawliszyn J Analytical Chemistry 66 1994 pp 160 167 44 03 91483500 1 Flavor Analysis of a Fruit Beverage With Automated Solid Phase Microextraction SPME Varian Application Note Number 4 Zelda Penton Varian Chromatography Systems Key Words Solid phase microextraction SPME 8200 AutoSampler foods and flavors Trace quantities of compounds in foods are often critical in imparting the proper taste and aroma to a product In other cases a very small quantity of a particular compound may be responsible for causing a food product to have an off taste or odor These trace compounds are usually present in very complex mixtures and quantifying them presents an analytical challenge GC or GC MS combined with static headspace dynamic headspace or thermal desorption is normally used in these applications A new sample introduction technique solid phase microextraction SPME offers the possibility of becoming a strong competitor of established methods With SPME analytes in the liquid sample or in the headspace above the sample are adsorbed onto fused silica fibers coated with a polymer such as polydimethylsiloxane or polyacrylate The fiber is then inserted into a GC injector for desorption The system has been automated with the Varian 81 8200 AutoSampler 1 In previous work 2 with volatile n
53. ecovery of toluene in the presence of Drug B with a heated static headspace system Static Headspace 20 min equilibration neutral pH saturated with sodium sulfate 50 C 80 C 38 46 It was found that elimination of the sodium sulfate and lowering the pH to 2 greatly improved the recovery of toluene The sodium sulfate was added originally per USP Method IV to improve the response of the polar compounds Elimination of the salt and lowering of the pH increased the solubility of the drug pKa was 9 4 thereby improving the partitioning of the toluene into the headspace and ultimately into the fiber Under these conditions the recovery with SPME sampling was 73 More important recoveries were consistent when the drug was spiked with toluene at the three levels mentioned above linear correlation coefficient was 0 999 Quantitation could be by the method of standard additions or by comparison of a sample containing toluene with a toluene free drug sample spiked to a known level 38 Conclusion For the determination of residual solvents in pharmaceuticals SPME offers sensitivity and precision that greatly exceed the USP requirements As compared to a static headspace system SPME is compact and offers comparable sensitivity and full automation at a lower cost In comparison with Method which normally involves direct injection of water the sensitivity with SPME was greater by factors varying from 2 dioxane to 90 T
54. ectrometry Bartelt R J 1997 Calibration of a Commercial Solid Phase Anal Chem Vol 69 pp364 372 Microextraction Device for Measuring Headspace Concentrations of Organic Volatiles Berg J R 1993 Practical Use Of Automated Solid Phase AM LAB SHELTON CONN VOL 25 Microextraction 17 PP 18 20 22 4 Boyd Boland A A 1996 Solid Phase Microextraction Coupled With High ANAL CHEM 68 9 PP 1521 9 PAWLISZYN y B Performance Liquid Chromatography For The Determination Of Alkylphenol Ethoxylate Surfactants In Water Boyd Boland A A Chai 1994 New Solvent Free Sample Preparation Techniques Environ Sci Technol 28 13 pp 569 M Luo Y Zhang A Yang M Pawliszyn J Gorecki T Combi PAL based on Fiber and Polymer Technologies A 574A 19 AUTHOR S Boyd Boland A A Magdic S Pawliszyn J Brand G Buchholz K D Pawliszyn J Buchholz K D Pawliszyn J Chai M Arthur C L Pawliszyn J Belardi R P Pratt K F Chai M Pawliszyn J Chen J l Pawliszyn J B Daimon H Pawliszyn J De la Calle Garcia D Magnaghi S Reichenbacher M Danzer K Dean J J Tomlinson W R Makovskaya V Cumming R Hetheridge M Comber M Eisert R Levsen K Eisert R Pawliszyn J Eisert R Pawliszyn J Furton K G Bruna J Almirall Gorecki T Pawliszyn J Gorecki T Pawliszyn J Grote C Pawliszyn J Guo F Gorecki T Iris
55. entrations ranging from 44 ppb to 2 ppm dissolved in HPLC water and in water containing 12 ethanol Wine samples Amber Australian Muscat with 18 alcohol 1 light California Muscat with 9 alcohol 2 California Cabernet Sauvignon table wine with 10 14 alcohol 3 Sampling Determine if the terpene alcohols are absorbed onto the SPME fiber effect of sampling from water versus water ethanol Effect of saturating samples with Na2SO4 headspace versus liquid sampling Comparison of fibers Response versus sampling times with PDMS and polyacrylate fibers These preliminary studies were done with the FID Identification of compounds in wine samples with ion trap detection and linearity minimum detection limits and precision of results in spiked wine with the ion trap Minimum detection limits with FID E water E water salt 12 ethanol 712 ethanol salt Detector Response linalool citronellol nerol geraniol Figure 2 Relative FID responses with SPME sampling of terpene alcohols in aqueous solutions at 2 ppm each headspace sampling 100 um PDMS fiber The salt is Na2SO saturated Geraniol 53430 Nerol 72386 Citronellol 119467 Linalool 151180 Liquid Sampling 1 2 mL 52 201114 337006 185833 165728 03 91483500 1 Table 1 FID responses area counts after sampling terpene alcohols 2 ppm in a 12 ethanol water mix with a 100 um P
56. ese volatiles Several different SPME fibers were compared for relative efficiency in extracting the analytes of interest then linearity and precision were studied A comparison was made with conventional static headspace SHS for this application ECD Detection MW 9 2 3 butanedione diacetal 86 09 oh 0 O 2 3 pentanedione 100 12 oh Io 0 MS Detection H trans 2 nonenal 102 PES ASAS AA trans trans 2 4 decadienal 152 2 CHa a AN AN AANA H ethyl esters Figure 1 Structures of compounds monitored in beer Instrumentation and Conditions While the aldehydes are easily detected at very low levels with the ion trap detector the diones fragment into small ions butanedione mass 43 and ECD at 150 C pentanedione masses 43 and 57 Since the background contains nu merous interfering ions with the same masses sensitivity is poor For the same reason sensitivity is not improved in the chemical ionization mode CH3 However the diones give a strong signal with ECD detection this signal is temperature dependent with significantly more sensitivity at a detector temperature of 150 C than at 220 C Figure 2 Therefore the system was configured so that both ECD and ion trap detection could be used Figure 2 Response for butanedione vs ECD temperature Combi PAL 85 A 4 port switching valve Figure 3 allowed the effluent from the analytical column to pass through the ECD to detect the early elu
57. euticals volatiles Introduction The 1995 United States Pharmacopeia USP National Formulary 1 lists four methods for determining organic volatile impurities in pharmaceutical compounds All of the procedures utilize gas chromatography with flame ionization detection and either direct liquid injection or static headspace Table 1 Table 2 lists the organic volatiles and the maximum allowable quantities in pharmaceutical compounds and in addition lists the concentration of these components in a standard solution The area count precision required for replicate determinations of the compounds in the standard solution is 15 relative standard deviation Table 1 Summary of the USP methods Column Method 0 53 mm fused silica l 5 phenyl 95 methylpolysiloxane Sample Introduction Direct injection of 1 uL IV 6 cyanopropylphenyl Static headspace 1 mL 94 dimethylpolysiloxane V 6 cyanopropylphenyl Direct injection of 1 uL 94 dimethylpolysiloxane VI Direct injection of 1 uL Usually water unless another solvent is specified in the monograph for a particular drug Method VI is used when a procedure is written for a particular pharmaceutical in that case a column is specified Combi PAL The following note describes the use of solid phase microextraction SPME for determining solvents in pharmaceuticals Table 2 Organic volatile impurities and maximum allowable levels in pharmaceuticals The concentrations in the
58. fied with the components of test sample 1 and detection limits for these compounds with SPME were compared with other sample introduction techniques Table 2 Precision data for these sampling methods are shown in Table 3 42 03 91483500 1 Table 2 Summary of data obtained with sample 1 including correlation coefficients r to a straight line for SPME liquid sampling and minimum detection limits S N 4 with different sample introduction methods SPME liquid and headspace values were similar Minimum Detectable Quantities ppb Compound r SPME SPME SHS SHS Purge and Direct liquid liquid ambient heated Trap Injection Dichloromethane 12 10 0 7 0 05 80 Chloroform 8 6 20 1 5 0 04 240 Benzene 0 3 1 4 0 1 0 003 17 Trichloroethylene 1 2 8 5 0 8 0 01 108 Dioxane 45 900 5 9 0 6 94 Toluene 0 18 2 2 0 2 0 003 20 m Xylene 0 13 3 3 0 2 0 003 26 1 2 4 Trimethylbenzene 0 12 3 6 0 2 0 005 29 Eight levels 3 samplings at each level for concentration ranges of 20 ppb to 4 ppm 10 ppb to 2 ppm for chloroform With the exception of dioxane and 1 2 4 trimethylbenzene all of the compounds in sample 1 are regulated in drinking water by the USEPA and many European countries Of these compounds only dichloromethane was not detected with SPME below the maximum contaminant levels With electroconductivity detection it would have been possible to meet the required levels 5 10 ppb for dichloromethane Table 3 Area count precision for each sa
59. following sequence Menu Utilities Syringe Scroll through the various parameters until you reach Standby Pos and press enter With your thumb push up the lower needle guides until the end of the protective needle is visible If the fiber is not exposed turn the dial counterclockwise until you can see the fiber Then turn the dial clockwise slowly until the end of the fiber is flush with the end of the hollow tube Turn the dial clockwise an additional 0 1 mm Enter the value and press F4 Home This procedure should be repeated whenever a fiber is installed Position of the fiber in the GC injector If you are using a Varian 1078 1079 injector with or without a Merlin Microseal the default parameter in the software is set correctly for fiber desorption For other injectors the procedure is 1 Access the method Test SPME see the Combi PAL System user manual 8 03 914835 00 1 2 Build a job list with one vial and the method Test SPME 3 Press F4 Start 4 While the fiber is desorbing in the injector mark the fiber holder to record the position of the small metal circle see Figure 6A during the desorption step 5 After the cycle is completed remove the fiber holder from the Combi PAL Line up a septum nut septum and injector insert Figure 6B 7 Push the fiber needle through the septum nut and septum into the insert Push the plunger down to the mark on the fiber holder 8 When the fiber
60. for both BTEX PID and gasoline FID In the case of BTEX the calibration range was 1 ppb ng mL to 1 ppm ug mL for benzene and toluene and 3 ppb to 3 ppm for xylenes in water Xylenes were integrated as a group Gasoline was quantitated as a group and calibrated from 10 ppb to 10 ppm in water A calibration curve for toluene is shown in Figure 4 benzene xylene and gasoline calibration curves are similar Retention time precision was excellent Area precision was determined using six replicate injections for both BTEX and gasoline Minimum detectable limits MDLs on each were also calculated from 10 replicate runs EPA type MDLs were calculated using the formula MDL s x t where s is the standard deviation of the replicate analyses and t is the students t value appropriate for a 99 confidence level The results are listed in Table 1 below Table 1 Area Precision and MDLs for BTEX and TPH in Water Area RSD 6 replicates MDL ppb 10 replicates Conclusions SPME coupled with FastGC provides a very rapid turnaround method for the analysis of BTEX and TPH in water Ambient headspace SPME allows rapid selective sampling of volatiles only and unlike purge and trap is not subject to contamination by samples at very high concentrations 2 Linearity precision and sensitivity are excellent and the method was found to be reliable over several hundreds of runs There is obviously a huge time and cost saving advantage to this technique
61. gure 1 Plot of the ion at m z 94 following a SPME sampling of a vial containing 100 pg of phenol The retention time of phenol was 7 59 minutes Counts II IM u nl N N MW UY N YI UN IN lt il I iH UWE 5 6 rd 8 9 10 minutes Figure 2 Narrow scan MS MS TIC chromatogram daughter ions of m z 94 related to a SPME headspace GC MS MS analysis of a vial containing 10 pg of phenol 03 91483500 1 Water Extraction Distillation Preliminary Quantitative Determination Spectrophotometric Analysis Figure 3 Comparison between the SPME GC MS method and the spectrophometric method References 1 Kirk Othmer Encyclopedia of Chemical Technology 3 Edition Wiley Interscience John Wiley amp Sons New York NY 1981 Vol 13 pp 253 277 The linearity of the method was not evaluated because the producer of the recycled paper who gave us this job was interested in knowing the approximate value of phenol in the fibers and these data were sufficient for his needs Combi PAL 99
62. h D Pawliszyn J Harmon A D Hawthorne S B Miller D J Pawliszyn J Arthur C L Horng J Huang S Iwasaki Y Yashiki M Nagasawa N Miyazaki T Kojima T 20 YEAR 1996 1994 1993 1994 1993 1995 1995 1996 1996 1996 1995 1997 1997 1995 1995 1995 1997 1996 1997 1992 1994 1995 TITLE Simultaneous Determination of 60 Pesticides in Water Using Solid phase Microextraction and Gas Chromatography Mass Spectrometry Evaluation Of Solid Phase Microextraction Spme Technology For Applicability to Drinking Water Analysis Determination Of Phenols By Solid Phase Microextraction and Gas Chromatographic Analysis Optimization Of Solid Phase Microextraction Conditions For Determination Of Phenols Determination Of Volatile Chlorinated Hydrocarbons In Air And Water With Solid Phase Microextraction Analysis Of Environmental Air Samples By Solid Phase Microextraction And Gas Chromatography lon Trap Mass Spectrometry Solid Phase Microextraction Coupled To High Performance Liquid Chromatography High Temperature Water Extraction Combined With Solid Phase Microextraction Systematic Optimization of the Analysis of Wine Bouquet Components by Solid Phase Microextraction Solid Phase Microextraction As A Method For Estimating the Octanol Water Partition Coefficient Determination Of Pesticides In Aqueous Samples By Solid Phase Microextraction I
63. h the detection limits were less than 1 ppb Table 2 gives the precision and minimum detectable values for the compounds sd BK Carboxen PDMS fiber 3 56 2 82 5 70 8 59 SHS 5 20 5 73 n d n d Carboxen PDMS fiber 0 2 0 1 1 4 2 1 SHS 4 3 n d n d 6 samplings at 100 ppb 8 samplings at 50 ppb Table 2 Precision and minimum detectable quantities for the four compounds of interest in spiked beer 2 3 butanedione 1 2 3 pentanedione 2 trans 2 nonenal 3 and trans trans 2 4 decadienal 4 Compounds 1 and 2 were detected with an ECD 3 and 4 were detected with the Saturn 88 03 91483500 1 In addition to the four compounds that were spiked into the beer samples for the study additional compounds were identified in the beer samples These are shown in the chromatogram Figure 5 Figure 5 Total ion chromatogram of beer sampled with the polyacrylate fiber The compounds were identified as 1 ethanol 2 ethyl octanoate 3 ethyl decanoate 4 ethyl dodecanoate 5 phenylethanol and 6 octanoic acid Conclusions The data indicated that SPME is a practical technique for detecting diones and aldehydes that are monitored in beer The polyacrylate fiber was useful for general screening of all of the compounds in beer including the less volatile ethyl esters The carboxen fiber would be the natural choice to determine the diones at very low levels althoug
64. h this fiber was less efficient at extracting the less volatile compounds Both SPME fibers were able to sample a wider range of compounds than the conventional static headspace autosampler Combi PAL 89 90 03 91483500 1 Determining Sulfur Volatiles in Beer with S P M E Automated SPME and PFPD Detection Varian Application Note Number 16 Zelda Penton Varian Chromatography Systems Key Words SPME 8200CX Food PFPD Sulfur Volatile sulfur compounds are routinely monitored in beer and other beverages because their presence even at trace levels can affect the flavor In this note beer was sampled using a Carboxen PDMS SPME fiber that has a strong affinity for highly volatile compounds A highly selective pulsed flame ionization detector PFPD was used to detect sulfur volatiles Some of the compounds in the beer were tentatively identified by matching retention times to sulfur standards lon trap chromatograms of the beer samples were studied and on this basis an additional compound was identified 1 7 Peak No R T Identity 5 6 1 1 690 Dimethylsulfide lt 4 2 2 721 Diethylsulfide At 3 4 998 4 5 285 Dipropylsulfide 5 9 728 6 18 005 7 21 558 3 Methylthio 1 propanol aA Figure 1 Profile of sulfur compounds in two beer samples top Budweiser Light bottom Michelob Amber Bock screened by headspace SPME using a Carboxen PDMS fiber and PFPD detection Instrumentation and Conditions The beer sam
65. he beer with salt Na2SO liquid versus headspace sampling and agitation Table 1 shows the results of these investigations Quantitative data for the aldehydes was obtained using mass 81 for trans 2 nonenal and the sum of masses 81 and 83 for trans trans 2 4 decadienal Parameter Area Count Ratio 1 2 3 4 Salt saturation Na2SO Salt no salt 1 6 2 0 1 0 1 5 Fiber coating Polyacrylate 100um PDMS 2 0 1 5 0 53 0 64 Carboxen PDMS 100um PDMS 147 24 6 0 35 0 07 Phase sampled Liquid headspace 1 2 1 1 1 8 2 2 Liquid plus agitation headspace 1 4 1 3 1 6 2 8 Table 1 Effect of varying SPME parameters on area count ratios of the four compounds of interest in spiked beer 2 3 butanedione 1 2 3 pentanedione 2 trans 2 nonenal 3 and trans trans 2 4 decadienal 4 The data in the table shows a very significant enhancement of response for the diones with the carboxen fiber Saturating with salt also enhanced the response for these compounds however it was felt that saturation with salt was too inconvenient for routine monitoring Figure 4 is a chromatogram of beer spiked with the four compounds of interest mass 81 BE oie total ions gt masses 81 83 a hee IN I 10 45 20 25 30 0 8 minutes 8 40 minutes GC ECD GCMS Figure 4 SPME chromatogram of headspace over beer sampled with a polyacrylate fiber The beer was spiked with 100 ppb 2 3 butanedione 1 2 3 pentanedione 2 trans 2 no
66. he vials was sampled at ambient temperature Empty vial B T T Cc T T T T T T T 0 5 10 15 20 Retention time min Figure 1 Total ion chromatograms of air sampled with a SPME fiber from a blank vial and vials containing three different packaging materials Peaks 1 and 2 were tentatively identified as butylated hydroxytoluene and 2 6 bis 1 1 dimethylethyl 4 ethylphenol Combi PAL 79 Instrumentation and Conditions Instrument Varian Saturn 2000 GCMS equipped with an automated SPME III system Column 30 m x 0 25 mm coated with 0 50 um Supelcowax 10 50 C 1 minute 10 C min to 210 hold 8 min Carrier gas helium 41 cm s at 60 C Injector SPI with SPME insert at 210 C isothermal lon trap Electron impact ionization mode mass range 50 250 m z ion trap temperature 200 C Automated Fibers Supelco Inc were coated with 100 um Polydimethylsiloxane SPME Headspace sampling without agitation in 2 mL vials 30 minutes absorption 2 minutes desorption one Conditions sampling per vial Samples Three different packaging materials Results and Discussion The samples were cut into one cm squares and placed in the vials one piece per vial Samples were run in duplicate with an empty vial at the beginning and end of the series The total ion chromatograms were inspected at comparable attenuation Figure 1 clearly shows the differences in the packaging materials Note that duplicates of the same sa
67. he waste stream Typically residual levels of less than 4 ppb must be Detector FID 250 C Range 10 12 achieved Figure 1 100 ppb ng mL Therminol in Water Column 15m x 0 32 mm 1 m DB 5 130 C hold 5 minutes Helium carrier gas at 5 mL min at 130 C SPME Parameters Liquid adsorption for 10 minutes The analysis of Therminol in water has previously desorbed tor 2 minutes been accomplished using liquid liquid extraction and direct injection and analysis of the extract with gas chromatography GC Solid phase microextraction SPME is well suited for the analysis of trace organics in water 49 Results and Discussion Initial development work was carried out with the use of a 100 um fiber SPME and GC conditions are described above and Figure 1 shows a 100 ppb ug L standard Although the upper temperature limit of this 100 um fiber is 220 C it was found that a desorption temperature of 250 C gave better peak shapes The higher temperature was necessary to provide rapid desorption from this relatively thick film fiber The high desorption temperature resulted in some fiber bleed Quantitation was therefore based on the larger diphenyl oxide peak which was free of interference In this manner quantitation to lt 1 ppb was readily obtained on a 1 5 mL sample volume Figure 2 shows the calibration curve obtained for the 1 to 100 ppb concentration range Concerns regarding the stability of the 100 um coated fiber when
68. ials If required the limit of detection could be lowered by using the larger AutoSampler vials 10 mL sample and or by utilizing MSMS Conclusions As concluded by G recki et al manual SPME is a valid method for determining trace amounts of semi volatile pesticides in water The performance with the automated system was comparable that achieved by the eleven labs in the study with no carryover and good linearity and precision In addition the automated system yielded values that were in excellent agreement with the true values Reference 1 T G recki R Mindrup J Pawliszyn Pesticides by SPME Results of the Round Robin Test submitted for publication to THE Analyst Combi PAL 77 78 03 91483500 1 Screening Packaging Materials with Automated SPME and GC MS Varian Application Note Number 13 Zelda Penton Varian Chromatography Systems Key Words SPME 8200CX Polymers Saturn Solid phase microextraction SPME was used to compare various packaging materials to assess their suitability for storing and shipping analytical materials In a previous publication SPME Application Note 7 polymeric beads that had been subjected to various heat treatments were compared in this note finished sheets were examined The various materials showed specific repeatable contamination patterns The technique was very simple approximately 1 cm of the various samples were placed into 2 mL screw cap vials and the air in t
69. immersing the fiber into water that is saturated with salt and is at pH 2 One sign of an aging fiber is deterioration of precision This might also be due to the aging of the septum When using a conventional GC septum it is best to change the septum when changing the fiber Is it necessary to use a septumless injector seal Users sometimes express concerns that the protective needle on the SPME fiber assembly might core the injector septum This is a real concern and a septumless seal as the Merlin Microseal is highly recommended However it is possible to get acceptable results with a conventional injector septum Figure 3 shows no change of retention time after 46 runs indicating that the septum is intact Again the practice at Varian is to change the septum and the fiber at the same time after about 100 runs according to the following procedure Install a septum Puncture the septum several times with the protective needle of the SPME fiber assembly Remove and inspect the new septum Remove any loose particles of septum material Reinstall the septum PoON gt Mean 8 74 minutes 065 RSD 8 76 8 75 8 74 8 73 R T NITROTOLUENE 8 72 4 8 12 16 20 24 28 32 36 40 44 NUMBER OF PUNCTURES Figure 3 Demonstrating the integrity of the injector septum after 46 SPME injections Note that the scale on the Y axis is 0 04 minutes A Thermogreen LB 2 Supelco septum was used in this study Combi PAL 29 What volume of sa
70. ith a split injection to two columns and flame ionization FID and photo ionization PID detectors This approach provides excellent selectivity and sensitivity for aromatics with the PID and an ability to simultaneously analyze TPH with FID Figure 1 shows a PID chromatogram of a 1 ppm BTEX standard with the xylenes eluting in about 0 3 minutes Figure 2 shows a 1 ppb BTEX standard illustrating the sensitivity of this technique For the analysis of gasoline quantitated as a group total elution time is approximately 1 6 minutes as shown in Figure 3 Combi PAL 67 Instrumentation and Conditions Instruments Varian Star FastGC with a split splitless injector FID and PID and 8200 CX AutoSampler modified for SPME The AutoSampler was controlled by SPME PC control software Data was collected and processed with the Star Workstation Columns 10m x 0 25 mm coated with 0 25 um DB1 80 C hold 2 9 minutes Carrier gas hydrogen at 4 mL min measured at 80 C Injector Split Splitless split mode 20 mL min vent flow 250 C FID amp PID 230 C FID range 10 12 PID range 10 11 Automated The fibers Supelco Inc were coated with 100 um polydimethylsiloxane PDMS SPME Headspace sampling over an 0 8 mL liquid sample in a 2 mL vial 2 minutes absorption Conditions 0 7 minutes desorption Standards 1 ppb to 1 ppm BTEX in water 10 ppb to 10 ppm gasoline in water for TPH Results and Discussion Linear 7 point calibration curves were generated
71. m polydimethylsiloxane fiber Adsorption time was 30 minutes desorption time was 2 minutes The peaks are identified in Table 1 For this sample area count precision varied from 1 7 2 7 rsd for the first 12 compounds precision for acenaphthene was 3 5 and phenanthrene was 5 9 5 replicates Results and Discussion Adsorption Times and Relative Responses With SPME Sampling of the Liquid or Headspace Phases When the liquid phase was sampled for various times a leveling off of response was observed for the more volatile compounds after about 10 minutes Figure 2 The trichlorophenol and the PNA s showed a much greater response after 30 minutes of sampling indicating that equilibrium was not attained for these compounds nevertheless after sampling for 30 minutes the precision was good Figure 1 legena 25 5 20 a T 1 min E10 min N30 min Relative response 5 r a T dl m o coma E ol oe l ol oe E u 2 E MeCi2 Benzen Dioxane Tolue m Xylene Chlorofor o Nitrophenol 2 6 Dimethylphenol p Chlorophenol 2 4 6 Trichlorophenol Acenaphthene Phenanthrene 1 2 4 Trimethylbenzene Figure 2 SPME responses for the compounds in test sample 2 after sampling the liquid phase for various times two minutes desorption The values at ten and thirty minutes are normalized to the values after one minute of sampling Concentrations are in Table 1 Combi PAL 41 The relative responses with
72. mall volume could be sampled minimizing risk of injury to the analyst and the SPME fiber The fiber was used for approximately 50 runs and then was used in another project with no discernible deterioration in performance Conclusions PME offered a simple solution to a difficult analytical problem A very corrosive sample could be analyzed in only 4 minutes with a minimum of sample handling For a discussion of the theory see Zhang and Pawliszyn Headspace Solid Phase Microextraction Analytical Chemistry 65 1993 p1843 1852 Combi PAL 61 62 03 91483500 1 Blood Alcohol Determination with S P M E Automated Solid Phase Microextraction SP ME Varian Application Note A Comparison with Static Number 9 Headspace Zelda Penton Varian Chromatography Systems Key Words SPME 8200CX Blood Alcohol Ethanol in the blood or urine of suspected intoxicated drivers is commonly measured using static headspace GC The technique is simple and analysis time is very short Unlike earlier methods which involved direct injection of diluted blood the injector insert and column remain clean and should last almost indefinitely It will be shown here that automated headspace solid phase microextraction SPME yields excellent results when determining blood ethanol and offers several advantages over conventional static headspace SHS autosamplers These include lower cost of capital equipment no detectable sample carryover and vers
73. mersed directly Injector SPI with insert for 530 um into an aqueous sample or into the headspace above a columns liquid or solid sample Organic compounds in the sample are subsequently adsorbed in the fiber Finally Detectors 220 C FID at range 10 ECD at the fiber is inserted into a GC injector where the range 10 analytes are thermally desorbed and separated on the GC column SPME Fiber coated with 100 microns Parameters polydimethylsiloxane Adsorb in the headspace 15 Although it is possible to purchase a fiber holder for minutes desorb one minute one manual operation automation is desirable to increase sampling per vial sample throughput and enhance repeatability A kit is available to upgrade a Varian 8100 or 8200 CX Samples po Sample DEP no food product added to a 2 mL fiber holder and fibers a chip to modify the The headspace was sampled over AutoSampler and Windows based software After the three alcoholic beverages and orange juice dry coffee beans modification the AutoSampler can easily be restored to and tea leaves liquid sampling if desired in a matter of minutes This article illustrates that SPME is suitable for fingerprinting foods and flavors and offers several advantages over competing techniques Combi PAL 33 Results and Discussion Chromatograms from the various samples are shown in the figures Only coffee contained compounds that elicited an ECD response os FRE cs os
74. mple should be added to the AutoSampler vials The AutoSampler vial should not be filled to the top It was observed when sampling volatiles that equilibrium was attained faster when headspace was present even when liquid was being sampled Furthermore immersion of the metal fiber support rod in the liquid sample may result in the adsorption and or breakdown of analytes y Headspace Liquid Do not fill Ithe vial A final reason not to fill the vial is the possibility of carryover if liquid sample enters the fiber needle What are the recommended extraction and desorption times Extraction time varies inversely with the volatility of the analyte and also depends upon the relative volumes of the phases in the vial Satisfactory precision can often be obtained without achieving equilibrium This is convenient if the GC cycle time is relatively short and prolonged sampling times would greatly lengthen the total analysis time A reasonable sampling time is fifteen minutes but extraction times may be longer if the GC cycle time permits At least two minutes is recommended to desorb all traces of the analytes to minimize carryover The injector temperature should normally be at least 200 C but should not be higher than the temperature limit of the analytical column or the SPME fiber If carryover is present a longer desorption time and or higher injector temperature should be used Is cryofocusing necessary Injector After initial studies it
75. mple were virtually identical Figure 2 The method is not quantitative as one would expect the quantities of the various compounds released from the packaging material to be proportional to the surface area but if similar sized pieces of the materials are placed in the sampling vials the relative cleanliness of the different samples becomes obvious Figure 2 Total ion chromatograms of two samples of packaging material B Conclusions SPME is a very simple and effective technique for rapidly evaluating the cleanliness of packaging materials A simple GC FID system may be used for fingerprinting or if identification of the contaminants is required GC MS should be utilized 80 03 91483500 1 Determination of Acetone and C Cz Alcohols using Automated SPME Sonia Magdic and Janusz Pawliszyn University of Waterloo Chemistry Department Waterloo Ontario Canada Varian CSB Contact Zelda Penton Key Words SPME 8200CX Alcohol Beverages Introduction Solid phase microextraction SPME is a solvent free analytical technique that is significantly more rapid and simple than the conventional methods currently employed to determine alcohol 1 The SPME device is commercially available and is comprised of two major components the syringe assembly and fiber assembly The syringe serves as a holder for the fiber assembly which is comprised of a needle that protects a small diameter fused silica fiber that has been coated
76. mpling method at the 2 ppm level 1 ppm for chloroform SPME liquid and headspace values were similar RSD Compound SPME SHS SHS Purge Direct liquid ambient heated and Trap Injection Dichloromethane 0 9 1 1 1 3 7 5 2 0 Chloroform 1 1 2 0 1 4 0 6 3 3 Benzene 1 7 1 3 1 4 0 7 5 0 Trichloroethylene 2 2 1 5 1 4 1 2 8 8 Dioxane 2 0 14 2 6 10 5 7 0 Toluene 2 6 2 4 1 5 1 5 13 m Xylene 2 8 1 7 1 7 3 0 2 8 1 2 4 Trimethylbenzene 2 7 2 2 1 8 4 4 8 2 Conclusions It was shown that the automated SPME system can deliver linear and precise data with sensitivities comparable to heated headspace for volatiles and semivolatiles in water In fact the phenols and PNA s in the sample could be detected in the headspace with SPME but not with heated headspace Although specialized fibers might be used to give optimum results with compounds such as phenols or PNA s 2 3 the 100 um polydimethylsiloxane fiber was useful for a sample containing a wide range of compounds Finally it appears that SPME generally meets the guidelines for contaminants in drinking water and further study for this application is warranted Combi PAL 43 References and Additional Reading 1 Automation and Optimization of Solid Phase Microextraction Arthur C L Killam L M Buchholz K D Pawliszyn J and Berg J R Analytical Chemistry 64 1992 pp 1969 66 2 Method Development Tips for the Automated SPME System Penton Z Varian GC Advantage Not
77. n Line Coupled To Gas Chromatography Mass Spectrometry Design of Automated Solid Phase Microextraction for Trace Analysis of Organic Compounds in Aqueous Samples Automated In Tube Solid Phase Microextraction Coupled to High Performance Liquid Chromatography A Simple Inexpensive Rapid Sensitive And Solventless Technique For The Analysis Of Accelerants In Fire Debris Based On SPME Solid Phase Microextraction Isothermal GC For Rapid Analysis Of Complex Organic Samples Sample Introduction Approaches For Solid Phase Microextraction Rapid GC Solid Phase Microextraction For The Analysis Of Human Breath Solid Phase Microextraction Combined With Electrochemistry Solid Phase Microextraction for the Analysis of Flavors Solventless Determination Of Caffeine In Beverages Using Solid Phase Microextraction With Fused Silica Fibers Determination Of The Semi Volatile Compounds Nitrobenzene Isophorone 2 4 Dinitrotoluene And 2 6 Dinitrotoluene In Water Using Solid Phase Microextraction With A Polydimethylsiloxane Coated Fiber Analysis of Inflammable Substances in Blood Using Headspace Solid Phase Microextraction and Chemical lonization Selected lon Monitoring REFERENCE Analyst 121 pp 929 938 Proc Water Qual Technol Conf Part 1PP 273 83 ENVIRON SCI TECHNOL VOL 27 13 PP 2844 2848 ANAL CHEM VOL 66 1 PP 160 7 ANALYST CAMBRIDGE U K VOL 118 12 PP 1501 5 ENVIRON SCI TECHNOLVOL 29 3 PP 693 7
78. nenal 3 and trans trans 2 4 decadienal 4 Combi PAL 87 Linearity Precision and Minimum Detectable Quantities The Michelob Amber Bock beer samples were spiked with the compounds of interest at levels of 25 ppb to 1 ppm for linearity determinations with the polyacrylate fiber and SHS For sampling with the Carboxen PDMS fiber the spiking level was 10 ppb to 250 ppb The ECD was saturated above this level In all cases the ECD response curves for the diones showed a better fit to a quadratic curve than to a linear curve For example when 2 3 butanedione was sampled with the polyacrylate fiber the correlation coefficient r toa straight line was 0 9990 r was 0 9997 for a quadratic curve fit The r values were 0 9988 linear and 0 9998 quadratic with SHS and 0 9959 linear and 0 9987 quadratic for SPME sampling with the Carboxen PDMS fiber The unspiked beer samples contained 25 50 ppb 2 3 butanedione and 5 18 ppb 2 3 pentanedione To establish a blank value it was necessary to sample bottled drinking water that had been vigorously boiled to remove interfering compounds The ion trap responses to the two aldehydes were linear with SPME sampling The correlation coefficients to straight lines were 1 000 for both compounds when sampled with the polyacrylate fiber These compounds were not reliably detected with SHS at the levels studied The unspiked beer samples did not show any trace of these compounds with SPME sampling althoug
79. nes with up to 20 ethanol the fibers were not saturated The PDMS fiber resulted in slightly less sensitivity than the polyacrylate fiber but precision was slightly better This might have been due to shorter equilibration time with this fiber 54 References and Additional Reading 1 Research on the Terpenic Composition of Galician Musts and Wines by GC MS Garcia Jares C M Carro Marino N Muniz Alonzo G and Cela Torrijos R Proceedings of the Sixteenth International Symposium on Capillary Chromatography ed by P Sandra and G Devos 1994 pp 602 609 2 Flavor Analysis of a Fruit Beverage With Automated Solid Phase Microextraction Penton Z Varian GC Application Note 51 3 Automation and Optimization of Solid Phase Microextraction Arthur C L Killam L M Buchholz K D Pawliszyn J and Berg J R Analytical Chemistry 64 1992 pp 1969 66 03 91483500 1 Determination of Residual Solvents and Monomers in S P M E Polymers with Solid Phase Microextraction SPME Varian Application Note and GC MS dai Zelda Penton Varian Chromatography Systems Key Words Solid Phase Microextraction SPME 8200 AutoSampler Polymers GC MS Polymers are found in numerous products including food wrappings utensils for eating and cooking insulation fabrics etc To assure the safety of the end user as well as for quality assurance it is critical that these compounds be monitored to verify
80. new technique linearity was demonstrated it was deemed unnecessary to verify the linearity with the other well established sample introduction methods To further verify the effectiveness of SPME for SHS purge and trap and finally the automated solid phase microextraction SPME system described previously 1 samples containing several different classes of analytes a second test sample was prepared This sample contained all of the compounds in the first sample plus several phenols and two polynuclear aromatic hydrocarbons PNA s With this sample adsorption time versus detector response was examined and relative responses were determined for liquid and headspace SPME sampling A test sample was prepared that contained mostly non polar organics with a wide boiling point range 40 170 C The sample was analyzed utilizing each of the above sample introduction methods Instrumentation and Conditions Instruments Varian Star 3600 CX GC with a septum equipped temperature programmable injector SPI FID and 8200 CX AutoSampler The AutoSampler was used in the liquid injection ambient headspace and SPME modes During SPME operation the AutoSampler was controlled by the SPME software and the GC was controlled by the Star Workstation in the liquid and headspace injection modes the GC Star Workstation also controlled the AutoSampler The Star Workstation and Excel Macros were used for data acquisition and summary reports F
81. ning the SPME test sample The SPME Sensitivity Test Sample is composed of 1 ng uL each of nitrobenzene and nitrotoluene in water 1 methanol has been added to stabilize the sample These compounds were selected because they exhibit a good response with many GC detectors including the flame ionization detector the electron capture detector the thermionic selective detector and the ion trap detector To run the SPME Sensitivity Test Sample use the following conditions Column Nearly any capillary column can be used to separate the components in the test sample For a non polar fused silica column the following conditions are suggested 50 C for 1 minute then 20 C minute to 150 C hold for 2 minutes carrier gas flow appropriate for the column Injector 200 C isothermal Detector Settings depend on the detector used Suggested SPME conditions 100 um PDMS fiber conditioned according to the instructions in the package Place the entire sample in a vial Extract 10 minutes and desorb one minute Heating and agitation are not necessary A representative SPME test sample chromatogram is shown Figure 9 GC CONDITIONS Injector 200 C Column 4m x 0 53um fused silica coated with 1 micron methyl silicone 50 C min hold 1 min 20 C to 110 C hold 2 min Detector 240 C FID range 10 attenuation 128 1 Nitrobenzene 2 Nitrotoluene Figure 9 Chromatogram of the SPME test sample Combi PAL 13 14 03 914835 0
82. nzaldehyde p ppb 7 Ethyl acetate 938 56 Ethyl butyrate 153 4 2 Ethyl isovalerate 151 Isoamyl acetate 153 34 Ethyl valerate 3050 Limonene 146 N Benzaldehyde 903 3 5 7 9 11 13 15 Retention Time min Figure 1 SPME sampling of the headspace over a fruit beverage with a 100 um PDMS fiber The compounds listed in the table were identified by GC MS 46 03 91483500 1 Results and Discussion Comparative Response and Equilibration Times with Two Fibers The test sample was analyzed using 100 um PDMS and 85 um polyacrylate SPME fibers and the comparative responses were evaluated after 20 minutes adsorption Figure 2 The graph in Figure 3 compares detector response versus adsorption time for the two fibers Response on 100 um PDMS fiber 0 2 0 0 Ethyl Ethyl Ethyl acetate butyrate isovalerate acetate Ethyl Limonene Benzaldehyde valerate Figure 2 Response on a polyacrylate fiber represented by the bars normalized to the response on a PDMS fiber 20 min adsorption FID Response 1004m PDMS 85m polyacrylate 0 10 2 Adsorption Time min 40 50 60 Figure 3 Equilibration study for isoamyl acetate with two SPME fibers The headspace over the test mix was sampled All of the compounds in the test mix exhibited similar behavior with the two fibers After 20 30 minutes adsorption with the PDMS fiber the slope of the curves leveled off indicating that equilibrium was reached this
83. oSampler vial When sampling the liquid phase verify that only the fiber not the support rod is submerged in the liquid phase A reasonable extraction time is 15 minutes followed by 1 3 minutes desorption however these conditions should be optimized for each analysis It is not necessary to achieve equilibrium if the total analysis time will be prolonged For many samples RSD s under 5 can be obtained prior to reaching equilibrium 10 Shaking Figure 2 the sample during extraction is beneficial for SPME extraction of semivolatiles but has little effect on volatiles 11 Heating the sample during extraction is very useful for sampling semivolatiles in the headspace over dirty 28 samples a HCH y HCH HCH z ii agitated 5 HCH Aldrin Heptachlor epoxide Endosulfan 4 4 DDE Dieldrin Endrin 12 4 4 DDD 13 Endosulfan Il 14 4 4 DDT 15 Endrin aldehyde 16 Endosulfan sulfate 17 Methoxychlor ll Lh 18 Endrin ketone mb mb A E Na not agitated Figure 2 Increased extraction of pesticides from water 2 ppb with shaking Sampling from the liquid phase at ambient temperature 03 914835 00 1 Frequently Asked Questions How Long Does a Fiber Last The fiber life will vary with experimental conditions but typically there is no evident deterioration in chromatography after 100 runs when desorbing into an injector heated to 220 C This is true even when
84. olymer sample 1 The chromatogram on the left resulted from sampling with a SPME fiber and the chromatogram on the right was derived from conventional heated headspace sampling The small peaks between peaks 1 and 2 and between 4 and 5 in the SPME chromatogram appear to be derived from the polymer sample as they were absent in blank runs Combi PAL 55 Instrumentation and Conditions Instruments Varian Saturn 3 GC MS with a septum equipped temperature programmable injector SPI FID and 8200 CX AutoSampler modified for SPME 1 A 486 DX PC was used to control the GC MS and collect MS data The same PC simultaneously controlled the AutoSampler in the SPME mode using 8200 CX PC control software A Varian Genesis Headspace Sampler was used for comparative studies with static headspace Column 30 m x 0 25 mm coated with 0 25 um Nukol 40 C hold 6 minutes 5Yminute to 180 C hold 3 minutes 20 minute to 200 C hold 5 minutes total run time 43 minutes Carrier gas helium 37 cm s at 60 C Injector SPI with SPME insert 200 C isothermal transfer line to mass spec 220 C Mass Spec lon trap temp 170 C electron impact ionization mode Segment 1 30 min mass range 45 170 u delay acquisition 1 5 min Segment 2 13 min mass range 50 220 u Automated SPME Fibers Supelco Inc were coated with 100 um polydimethylsiloxane PDMS Conditions Polymer samples 0 1 2 0 grams were placed in the 10 mL vials 45 minutes absor
85. on of analytes out of the fiber Compounds of lower volatility show a higher optimum temperature Figure 4 5 Set Point E 30 E 45 4 60 3 2 1 0 Benzaldehyde Guaiacol Piperonal Vanillin Ethyl vanillin Figure 4 Variation of response for various flavor compounds after SPME sampling of the headspace over flavored coffee at 30 45 and 60 C Fiber 85 um polyacrylate Note that heating is more useful with the higher boiling compounds Boiling point of benzaldehyde is 179 C vanillin is 285 C Combi PAL 31 Sample Handling Poor precision and accuracy often result from improper sample handling 1 Itis a common practice to prepare a stock solution of analytes in methanol and then add a small aliquot to water This method is acceptable with SPME and results are the same as those obtained by adding organics directly to water if the total level of methanol is less than 1 2 Saturation of the standards and samples with sodium chloride or sodium sulfate is useful in two situations The analytes are polar and soluble in water The samples contain salts and it is desired to minimize matrix differences 3 When determining acidic compounds such as phenols lower the pH for basic compounds such as amines raising the pH will enhance sensitivity 4 Itis important to keep the concentrations of all of the components in an aqueous solution sufficiently low so that they remain dissolved in water For volatile compounds
86. on of Flavor Components in Wines with S P M E Solid Phase Microextraction anses SPME GC and GC MS a en Zelda Penton Varian Chromatography Systems Key Words Solid phase microextraction SPME 8200 AutoSampler wine foods and flavors GC MS Characterization of volatiles in wines provides important information on the origin and method of preparation One class of volatiles terpene alcohols Figure 1 is critical in assuring the proper taste and aroma of wines particularly Muscat and Cabernet Sauvignon Previously these compounds were identified at the ppb level using capillary GC MS following a tedious sample preparation method The procedure included a 48 hour extraction with freon and fractionation using an Amberlite resin 1 CH CH3 Linalool Pa MW 154 24 CHy OH BP 198 C Citronellol CH MW 156 24 N Denon BP 224 5 C CH Nerol i CH3 MW 154 24 H BP 225 C CH OH Geraniol CH CH MW 154 24 BP 229 C CH Es 2 s H Figure 1 Structures and physical properties of terpene alcohols found in wines A simplification of the above sample preparation method was sought solid phase microextraction SPME and static headspace SHS were considered SPME offered a particularly attractive alternative the automated system costs less and consumes far less laboratory bench space than SHS A recent study with SPME involved determination of flavor volatiles in a fruit beverage 2 The excellent sensitivity and precision data suggested
87. on polar compounds the automated SPME system provided excellent sensitivity precision and good linearity for Combi PAL organics up to 1 2 4 trimethylbenzene thus providing an inexpensive and compact replacement for a static headspace system The current study extends this work to relatively polar volatiles A preliminary investigation 3 of the feasibility of SPME for extracting flavor components from various beverages looked promising Therefore a commercially available fruit beverage was studied systematically Several key components were identified by the manufacturer as being of interest in quality control The presence of these compounds was confirmed with GC MS and a test sample containing known quantities of these components was prepared In this note data is presented comparing the responses of these compounds on two SPME fibers with results from static headspace SHS Precision data is also given for the compounds in the fruit beverage with SPME and SHS 45 Instrumentation and Conditions Instruments Varian Saturn 3 GC MS with a septum equipped temperature programmable injector SPI FID and 8200 CX AutoSampler modified for SPME The AutoSampler was controlled by SPME software After confirmation of the identity of the critical compounds by MS the end of the column was installed in the FID At this point data was collected and processed with the GC Star Workstation and Excel macros A Varian Genesis Headspace S
88. ons Following the procedure the standard 10 ppm in methanol was diluted to 1 10 and 30 ppb in water The unknown sample was prepared by diluting 1 1000 A freshly diluted sample was to be prepared prior to each determination this was not considered practical for an automated system and all of the samples were placed in the autosampler carrousel prior to the analysis The protocol mentioned that addition of salt might increase the sensitivity of the method but specified that salt was not to be added to the samples in this test Each of the calibration standards and the unknown sample was run in triplicate The GC conditions and SPME sampling and desorption times given above were specified in the study protocol Experimental Procedure and Results The instructions for the manual extraction were followed using the automated system as described above A blank injection preceded the calibration and another blank followed the calibration Each of the pesticides was identified by comparison with the spectra provided and in addition by comparison with the spectra in the NIST92 library Figure 1 A is a total ion chromatogram of the 30 ppb standard some of the pesticides gave a very small response This may have been due partly to deterioration of the sample and to weak affinity of the SPME fiber for these particular compounds Nevertheless these pesticides were easily seen in the selective ion chromatograms Figure 1 B Blank runs confirmed the absence
89. or OFF OFF for sampling in the tray at ambient temperature without agitation A maximum of 80 C is suggested Agi Speed 100 750 rpm These are the speeds for the pre incubation period only Agitation speed during the extraction is fixed to protect the fiber Agi On Time Os 99s Set Os to turn off agitation during pre incubation and extraction Agi Off Time Os 99s Vial Penetr 22 0 31 0 mm Distance from top of vial septum to end of fiber Figure 7 Extract Time 00 00 10 23 59 59 Sampling time in liquid or headspace Desorb to None Waste 2 Normally an injector such as Front or Rear is entered here Inj Penetr 44 0mm 67 0mm Distance from top of injector nut to end of fiber Figure 6B Desorb Time 00 00 10 23 59 59 Time in injector Fiber Bakeout 00 00 00 23 59 59 For baking out the fiber after desorption in the optional bakeout station GC Runtime 00 00 30 23 59 59 Enter the complete GC cycle time including cool down and re equilibration to coordinate the Combi PAL and GC cycles After the incubation temperature is determined it is convenient to set the standby temperature of the agitator to this temperature Enter the following sequence from the Job Queue page Menu Utilities Tray Agitator Scroll down to Standby Temp and set the temperature Note To sample in the tray Agi on time must be set to 0 and Incubat Temp must be set to off 12 03 914835 00 1 Run
90. or comparison with static headspace and purge and trap a Varian Genesis Headspace Sampler and a Tekmar LSC 3000 purge and trap system with AQUATek 50 Automatic Liquid Sampler were used Column 30m x 0 53 mm coated with 3 um DB 624 40 C hold 1 minute 20 minute to 200 C hold 0 minutes for the second sample the final temperature was 220 C with a 10 minute hold carrier gas helium 37 cm s at 50 C Injector SPI with SPME insert 220 C isothermal FID 220 C range 10 Combi PAL 39 Sample Introduction Conditions for Sample 1 First three methods used the 8200 CX AutoSampler Direct Liquid Injection Automated SPME Ambient Headspace Heated Headspace Purge and Trap User defined solvent flush mode with 0 4 uL solvent plug water and lower air gap Sample volume 1 uL Fibers Supelco Inc were coated with 100 um polydimethylsiloxane Both headspace and liquid phases were sampled Volumes were 0 8 mL and 1 2 mL in standard 2 mL vials Adsorption times varied for equilibration studies but were normally 10 30 minutes with 1 2 minutes desorption Same sample volume as with SPME headspace 0 8 mL Injected 40 uL headspace Samples 10 mL in a 22 mL vial were heated to 75 C line and valve temperatures were 85 C Equilibration time was 4 minutes with mixing at 80 of full power for 7 minutes stabilization time was 2 minutes Sample loop was 500 uL Samples 5 mL were purged at 30 C for 11 minutes and des
91. orbed for 2 minutes Sample Introduction Conditions Samples for Sample 2 This sample was analyzed only by SPME and by The two test samples were prepared in HPLC water at the concentrations shown in Table 1 For SPME static headspace SHS The SPME conditions were headspace and SHS determinations the samples the same as for test sample 1 the SHS conditions were also the same except for the temperatures Initially the samples were heated to 85 C with line were saturated with Na2504 Test sample 2 was analyzed both at neutral pH and at pH 2 the low pH was required for consistent response of the phenols and valve temperatures of 95 C then the valve was Figure 1 is a SPME chromatogram of Sample 2 raise to 160 C and the transfer line was raised to 200 C Table 1 Components in the test samples 40 _ DIESER EIN ee ee mb mb E a Compound BP C Conc ppm 1 2 Dichloromethane MeCl2 40 2 0 4 Chloroform 61 62 1 0 2 Benzene 80 2 0 4 Trichloroethylene 87 2 0 4 Dioxane 101 2 0 4 Toluene 111 2 0 4 m Xylene 139 2 0 4 1 2 4 Trimethylbenzene TMB 169 171 2 0 4 2 6 Dimethylphenol 201 0 2 o Nitrophenol 215 216 0 2 p Chlorophenol 220 0 3 2 4 6 Trichlorophenol 246 0 2 Acenapthene 279 0 2 Phenanthrene 340 E 0 2 03 91483500 1 FID Response 13 gs 4 8 12 1 2 fi ER fi 5 f 7 6 8 10 12 14 16 Retention Time min Figure 1 SPME sampling liquid phase of test sample 2 with a 100 u
92. orresponding to A Determine the slope of the plot by linear regression Calculate the total area For calibration prepare a vial that does not contain the matrix The headspace volume in the vial should be equal to the headspace volume in the sample vials The calibration vials can be filled with glass beads with a volume that is the same as the volume of the samples oa fF wWN gt N Inject a known quantity of the analyte of interest into the calibration vial 8 Following steps 1 5 calculate the area corresponding to the known standard 9 Calculate the amount of volatile in the unknown by comparison of the area of the calibration standard to the area of the unknown external standard calculation Figure 2 shows a graph for a calibration standard and a sample 13 0 y 11 0 7 standard 9 0 F Natural Log Area Counts 7 0 1 2 3 4 Run Number Figure 2 Plot of multiple samplings of vinyl chloride from a sample of polyvinyl chloride polymer and a standard 94 03 91483500 1 After the method has been validated by demonstrating a linear response such as that shown in the graph a simplified form of equation 1 can be used which requires only two samplings A is the total area count A 2 A A is the area count of the first extraction A A2 A is the area count of the second extraction While results would be expected to be more accurate with more than two samplings equation 2 is practical fo
93. ples There are four points at each of four levels from 0 to 336 ppm The y axis is FID response The curve was extrapolated back to 392 ppm representing the concentration of methanol in the sample before spiking 60 03 91483500 1 The x intercept of the above curve was 392 corresponding to a value of 392 ppm w v methanol in the sample Precision of the four points in the above curve varied from 0 9 2 5 rsd The minimum detectable quantity was calculated to be 1 2 ppm s n 3 After the initial validation of the method by spiking the samples with several levels of methanol as shown here it would be necessary in future demonstrations to spike only one sample with one methanol standard Then 3 4 replicates of the spiked and unspiked sample could be run for calibration The other samples would not require spiking since the matrix does not vary from sample to sample Methanol Area Counts Volume in vial 200 uL 600 uL run 1 22597 21645 run 2 22622 22095 run 3 21877 22306 Table 1 Methanol area counts after SPME sampling with 200 versus 600 uL in the 2 mL vials When sampling polar compounds in aqueous matrices with static headspace or SPME headspace the relative volume of liquid to headspace phases in the vial has little effect on sensitivity6 this is shown in Table 1 Detector response to methanol was essentially unchanged when the volume of sample in the 2 mL vial was reduced from 600 to 200 uL Therefore a very s
94. ples and standards were extracted with SPME headspace as described below Instruments Varian 3600 GC equipped with a PFPD and a 1078 injector Automated SPME lll system Varian Star Workstation to control the GC and SPME autosampler and to collect data Column 30 m x 0 25 mm coated with 0 50 um Supelcowax 10 temperature program 50 C 1 minute 5 C min to 200 hold 8 min carrier gas helium 41 cm s at 60 C Injector 1078 isothermal splitless mode with SPME insert 220 C Relay program close splitter at 0 01 minutes open at 2 minutes PFPD Sulfur mode range 10 temperature 200 C Automated 75um Carboxen PDMS fiber SPME Headspace sampling over 0 8 mL in 2 mL vials 15 minutes absorption 3 minutes desorption one Conditions sampling per vial Beer Samples Michelob Amber Bock Budweiser Light Combi PAL 91 Results and Discussion Standard compounds were dissolved in water and retention times were matched to the compounds in the beer The standards are listed in Table 1 Compound Retention Time Identified in Beer H2S COS Ethyl mercaptan 1 633 Dimethyl sulfide 1 695 Isopropyl mercaptan 1 787 n Propyl mercaptan 2 171 Sec butyl mercaptan 2 414 Isobutylmercaptan 2 667 Diethyl sulfide 2 725 n Butyl mercaptan 3 158 Di n propylsulfide 5 278 n Hexyl mercaptan 6 858 Diallylsulfide 7 090 n Heptyl mercaptan 9 488 Table 1 Sulfur standards and retention times SPME Application Note 15 describes
95. pling Figure 1 and increasing the amount of phenol absorbed in a given time The only sample preparation required was to adjust the pH of the sample to 2 0 thus converting the phenols to the non ionized acid state and to saturate the sample with Na2SO4 The addition of salt had the effect of reducing the solubility of the phenols in water Phenols were detected at the low ppb level with good precision and linearity Fiber Depleted layer Analytes Figure 1 Schematic of SPME sampling showing the depletion of slow diffusing analytes around the SPME fiber Combi PAL 71 Instrumentation and Conditions Instruments Column Injector Detector Automated SPME Conditions Sample Varian Star 3400 GC with a 1078 temperature programmable split splitless injector FID and 8200 CX AutoSampler modified for SPME The Star Workstation controlled the GC and AutoSampler and acquired data The Advanced Applications for Excel were used to generate summary reports The new SPME agitation option was installed on the AutoSampler 30 m x 0 25 mm coated with 0 25 um DB 5 40 C 4 minutes 12 C minute to 260 C hold 1 67 minutes for a run time of 24 minutes Carrier gas helium 37 cm s at 60 C 1078 with SPME insert at 280 C isothermal Splitless mode close split relay at 0 01 minutes open at 3 minutes Flow through splitter 94 mL minute FID at range 10 300 C Fibers Supelco Inc were coated with 85 um poly
96. ption 5 minutes desorption one sampling per vial Heated Headspace Polymer samples 0 1 2 0 grams in 22 mL vials were heated to 120 C valve and transfer line temperatures were 130 Equilibration time was 45 minutes Sample loop was 500 uL Test plan Identify compounds released by the polymer samples with GC MS using SHS and SPME Inject pure standards of the solvents found for conclusive verification of identity Compare relative quantities of each compound after sample introduction with SPME and SHS Samples The polymer was made with acrylonitrile polybutadiene styrene methyl styrene and styrene butadiene rubber Samples were as follows 1 beads 2 beads extruded once at 220 C 3 beads extruded four times at 220 C 4 Sample 2 additional treatment proprietary Results and Discussion Identification of Solvents Figure 1 depicts total ion chromatograms of sample 1 using SPME and SHS respectively The compounds were identified Figure 2 using the NIST92 library then pure solvents were injected for additional confirmation A significant difference between the two chromatograms is the relative recovery of butylated hydroxytoluene with SPME This agrees with earlier studies showing that SPME tends to yield a higher recovery with relatively nonvolatile compounds than SHS For example the conditions given above for SHS caused overload in the ion trap for the first four compounds but very little sensitivity for the least
97. r routine analysis The area counts in the calibration sample would also be determined using equation 2 Results and Discussion Equation 1 was used to calculate the total area counts for two replicate runs of the standard and three replicate runs of the sample The mean of the total area counts for the standards was 157851 and the quantity of standard in each vial was 128 ng Equation 3 was used to calculate the weight of vinyl chloride in the sample where Asamp e IS the total area count of vinyl chloride in the sample and Astandara IS the total area count of vinyl chloride in the standard A sampie Wista 3 Wtsmp Samos ES dd A standard FID Area Counts Run Replicate 1 Replicate 2 Replicate 3 khOND Total area Weight vinyl chloride ng 676 671 from equation 3 Weight polymer g 0 9963 0 9988 0 9954 ng vinyl chloride g polymer 674 Mean rsd 697 5 2 Conclusion SPME is a convenient technique for determining monomers in polymers and the SPME multiple extraction method allows quantitation by minimizing the matrix effect Generally when a new quantitative method is being developed using SPME or another technique the sample should be analyzed by the new method and by a different technique and the results compared Reference 1 B Kolb Multiple headspace extraction a procedure for eliminating the influence of the sample matrix in quantitative headspace gas chromatography Chromatographia 15 587 594 1982
98. rug A using SPME Gena Data for precision and recovery of the solvents in the 7 Benzene 2 y 8 Trichloroethylene test sample are presented in Table 3 Correlation 9 1 4 Dioxane 2 coefficients to a straight line and LOD s are also given a The sample was in a 2 mL vial containing 0 8 mL test standard Drug B 16 mg was dissolved in the test standard Concentration of each solvent is in 3 7 le parenthesis next to the peak name Compounds 5 10 were initially dissolved in a stock solution with methanol as a solvent hence the methanol peak FID attenuation is 10 fold more sensitive before the arrow LN x 9 UU L J 1 6 2 3 4 5 Retention Time min Figure 1 Automated SPME chromatogram of the headspace over a test sample containing solvents monitored in pharmaceuticals The concentration in g mL is given next to each peak name Table 3 Precision data RSD area counts for 4 replicate determinations is given for the concentrations shown in the table linear correlation coefficients were determined by sampling at three levels 0 5 x 1 x and 2 x the values in the table The limits of detection LOD s are with FID detection S N 2 These values are for the standard mix to determine the limit of detection in a drug sample dissolved in water at a concentration of 20 mg mL the numbers should be multiplied by 50 Recoveries accuracies are calculated by comparing detector response
99. s from the septum bake the septum in a laboratory oven at 150 C overnight This will minimize extraneous peaks 15 16 03 914835 00 1 Supplies A AVarianpartnumber Combi PAL SPME kit 03 925903 91 SPME insert for 1078 9 injectors 03 925330 00 SPME insert for 1093 SPI injeblors 03 918832 05 Test sample SPME 03 918967 00 Merlin Microseal SPME Kit 23 Gauge for Varian 1078 1079 injectors 03 926099 01 Merlin Microseal SPME Replacement seal 23 Gauge 03 926099 02 Replacement O ring 27 402426 00 10 mL vials pk 100 MLA201000 20 mL vials pk 100 MLA202100 Seals for 10 20 mL vials 8 mm holes with septa pk 100 MLA200050ML Seals for wash and waste vials fit 10 mL vials above pk 20 MLAL1000023 Caps for wash and waste vials fit 10 mL vials above pk 10 MLAL1000118 23 gauge SPME fibers for Merlin Microseal SPME fiber PDMS Auto Merlin 100um pk 3 SU57341U SPME fiber Carboxen PDMS Auto Merlin 75um pk 3 SU57343U SPME fiber PDMS DVB Auto Merlin 65um pk 3 SU57345U SPME fiber Carbowax DVB StableFlex Auto Merlin 70um pk 3 SU57339U 24 gauge SPME fibers for conventional GC septa SPME fiber PDMS Auto 100um pk 3 03 918963 02 SPME fiber PDMS Auto 30um pk 3 03 918963 10 SPME fiber PDMS Auto 7um pk 3 03 918963 03 SPME fiber Polyacrylate Auto 85um pk 3 03 918963 06 SPME fiber Carbowax DVB Auto 65um pk 3 03 918963 12 SPME fiber Carbowax DVB StableFlex Auto 70um pk 3 SU57338U SPME fiber DVB PDMS Auto 65um pk 3 03 918963 1
100. se Static headspace response 2 0 1 0 oo E i Ethyl Ethyl Ethyl Isoamyl Ethyl Limonene Benzaldehyde acetate butyrate isovalerate acetate valerate Figure 4 SPME headspace 100 um PDMS fiber versus conventional static headspace response These results were derived from sampling the fruit beverage All of the conditions are in the text Conclusions SPME can deliver precise data with sensitivities comparable to heated headspace in the determination of flavor components in beverages Instrumentation is relatively inexpensive compact and versatile The SPME technique shown here to be a practical and inexpensive replacement for headspace should be widely used in analytical laboratories in the future References and Additional Reading 1 Automation and Optimization of Solid Phase Microextraction Arthur C L Killam L M Buchholz K D Pawliszyn J and Berg J R Analytical Chemistry 64 1992 pp 1969 66 2 Determination of a Wide Range of Organic Impurities in Water with Automated Solid Phase Microextraction Penton Z Varian GC Application Note 50 3 Profiling Flavors in Alcoholic and Non Alcoholic Beverages with Automated Solid Phase Microextraction Penton Z Varian GC Application Note 47 4 Optimization of Solid Phase Microextraction Conditions for Determination of Phenols Buchholz K D and Pawliszyn J Analytical Chemistry 66 1994 pp 160 167 48 03 91483500 1 Analysis of Therminol
101. sed silica tubing were used to connect the valve to the ECD and to the ion trap An auxiliary column 0 25 mm was also required see Figure 2 Injector SPI isothermal mode with SPME insert 210 C 230 C with the Carboxen PDMS fiber ECD Range 10 temperature 150 C sampled first 8 minutes of the run lon trap Electron impact ionization mode mass range 45 300 m z ion trap temperature 150 C transfer line temperature 180 C acquisition delay time 8 minutes Automated Fibers Supelco Inc were coated with 100um polydimethylsiloxane PDMS 85um polyacrylate and SPME 65um Carboxen PDMS Conditions Headspace sampling over 0 8 mL in 2 mL vials 38 minutes absorption 3 minutes desorption one sampling per vial Conventional 10 mL samples in 22 mL vials were heated to 70 C line and valve temperatures were 90 C equilibration Static time one hour Headspace Beer Samples Michelob Amber Bock Budweiser Light Standards Pure standards of the four compounds of interest 2 3 butanedione 2 3 pentanedione trans 2 nonenal trans trans 2 4 decadienal were dissolved in purge and trap grade methanol to concentrations of 1 mg mL each compound and then diluted into the beer samples at the level desired for the particular experiment 86 03 91483500 1 Results and Discussion Establishment of SPME Sampling Conditions To optimize SPME sampling the following parameters were studied response with various fibers effect of saturating t
102. sert 250 C Relay program inject with the split vent closed open at 5 minutes Carrier gas helium constant pressure mode 7 0 PSI flow 9 8 mL min Range 10 temperature 200 C 75um Carboxen PDMS fiber Headspace sampling over 1 gram in 16 mL vials 30 minutes absorption 2 minutes desorption four samplings per vial Special tested headspace septa for large vials were used p n 03 926100 03 These septa sealed after multiple samplings and allowed penetration of the SPME fiber without breakage 1 gram polyvinyl chloride powder weighed into 16 mL vials 500 uL vinyl chloride injected into a Super Syringe at 500 mL 50 uL of this mix was injected into a 16 mL vial that contained silanized glass beads so that the headspace volume was the same in the standards and the samples Combi PAL 93 Calculations In practice it is not necessary to extract more than three to six times and using the following equation the total area count can be calculated for each volatile in the sample A is the total area count 1 A m A is the area count of the first extraction 1 e k is the slope of the plot obtained by plotting the natural log of area counts versus the number of extraction steps k willbe a negative number The procedure is as follows Sample the polymer several times and determine the peak area A for each sampling Determine the natural log In of A Plot In A versus n 1 where n is the number of samplings c
103. sis One or two blanks should be run The AutoSampler vials containing the samples should be allowed to reach room temperature before starting the runs 32 03 914835 00 1 Profiling Flavors in Alcoholic and Non Alcoholic Beverages S P M E with Automated Solid Phase Microextraction Varian Application Note Number 1 Zelda Penton Varian Chromatography Systems Key Words solid phase microextraction SPME 8200 AutoSampler beverages food Flavors in foods and beverages are monitored by static Instrumentation and Conditions headspace GC and occasionally by thermal desorption Varian Star 3600 CX with a SPI FID and ECD and or parge and trap REES OE 8200 CX AutoSampler modified for SPME The chromatogram Wal Cal De examined t0 determine i AutoSampler was controlled by the SPME software Ine particular Sample Meets INE standards Serby se The GC Star Workstation ran concurrently on the same manufacturer or if components are present that might PC controlling the GC and collecting data adversely affect the taste of the product Column 30m x 0 53 mm coated with 3 um Solid Phase Microextraction SPME is a new DB 624 temperature program technique for introducing analytes into a GC that can be 40 C hold 1 minute 10 min to 210 C hold 7 min used in this application The technique utilizes a one cm Carrier gas helium at 37 cm s length of fused silica coated with an adsorbent The coated fused silica SPME fiber is im
104. standard solution assume a concentration of 20 mg mL for the pharmaceutical compound Standard USP solution Component Limit ug mL water ppm Methylene Chloride 500 10 Benzene 100 2 Trichloroethylene 100 2 Chloroform 50 1 1 4 Dioxane 100 2 Effective date 1 1 95 The results which included a recovery study on two pharmaceutical compounds indicated that SPME is a good alternative to liquid injection or static headspace An automated SPME system is considerably less expensive than a dedicated static headspace system and the problems of injecting aqueous samples into a GC are avoided Several additional solvents were considered in addition to the above to conform to compounds actually used in pharmaceutical companies These were ethanol acetone isopropanol and toluene 35 Instrumentation and Conditions 36 Varian Star 3600 CX with a septum equipped temperature programmable injector Instrument SPI FID and 8200 CX AutoSampler modified for SPME The AutoSampler was controlled by the SPME software The GC Star Workstation ran concurrently on the same PC controlling the GC and collecting data A Varian Genesis Headspace Sampler was used for comparative studies with static headspace f 30m x 0 53 mm coated with 3 um DBTM 624 35 C hold 2 minutes 20 min to Column 200 C hold 0 75 min Carrier gas helium at 38 cm s at 50 C SPI with insert for 0 53 mm columns 210 C isothermal Injector A AA 22
105. tatic Headspace The California Muscat wine was spiked with each terpene alcohol to a concentration of 130 ppb each compound Under the initial conditions 70 C sample temperature valve and line 85 C there was no response to the terpene alcohols Upon heating the valve and line to 170 and 190 C the chromatogram shown in Figure 5 resulted This may be compared to a SPME chromatogram of the same sample At the 2 ppm level SHS was found to be satisfactory for the terpene alcohols at the ppb levels required for this application there was insufficient sensitivity due to result with SHS was adsorption of the polar terpene alcohols along the sample path linalool citronellol nerol geraniol Al Aala T T T T 908 1008 1188 1208 1308 14 99 16 66 18 33 20 00 21 66 Figure 5 lon trap chromatograms sum of ions 67 69 and 71 of a Muscat wine spiked with 130 ppb terpene alcohols Left headspace sampled with a SPME fiber right static headspace sampling The scale of the chromatogram with static headspace was magnified approximately 10 fold so that the peak heights would be comparable Conclusions Without any sample preparation other than pipetting the wine into the AutoSampler vials SPME was found to be very effective for determining trace alcohols in wine at ppb levels Both PDMS and polyacrylate SPME fibers were useful The linear response upon spiking with analyte indicated that in wi
106. ter Analysis By Solid Phase Microextraction Based On Physical Chemical Properties Of The Coating Analysis Of The Petroleum Components Benzene Toluene Ethyl Benzene And The Xylenes In Water By Commercially Available Solid Phase Microextraction And Carbon Layer Open Tubular Capillary Column Gas Chromatography Enrichment Of Nitrophenols From Water By Means Of Solid Phase Microextraction Detection of Meperidine Pethidine in Human Blood and Urine by Headspace Solid Phase Microextraction and Gas Chromatography Rapid Analysis Of Environmental Samples Using Solid Phase Microextraction SPME And Narrow Bore Capillary Columns Analysis Of Environmental Samples Using Solid Phase Microextraction SPME Initial Bandwidth Resulting from Splitless and Solid Phase Microextraction Gas Chromatographic Injections Preconcentration and Determination of Sn and Pb Organic Species in Environmental Samples by SPME and GC AED Determination Of BTEX Compounds In Water By Solid Phase Microextraction And Raman Spectroscopy Determination of Chloroethenes in Environmental Biological Samples Using Gas Chromatography Coupled with Solid Phase Micro Extraction Solid Phase Microextraction Of Flavor Compounds A Comparison Of Two Fiber Coatings And A Discussion Of The Rules Of Thumb For Adsorption REFERENCE MIKROCHIM ACTA VOL 112 PP 41 6 ANAL CHEM 1995 67 23 PP 4396 403 J Chromatogr A Vol 773 1 2 pp249 260 ANAL CHEM
107. tes The following data represent typical results For further information contact your local Varian office Combi PAL 25 26 03 914835 00 1 SPME ERIZHIERI T SPME Advantage Note 5 Method Development Tips for Automated SPME Replaces GC Advantage Note 11 Zelda Penton Varian Chromatography Systems Key Words SPME Method Development Introduction Automated solid phase microextraction SPME can yield detection limits in the ppb range or better for organic compounds in water or solids Linearity is excellent and relative standard deviations are often better than 3 The purpose of this note is to help the novice become familiar with the SPME technique Experience has shown that sample preparation is the key to good results with SPME therefore techniques for working with volatile samples will also be discussed Some guidelines to help the user get started are given below These suggestions are discussed in greater detail in the following sections Guidelines for Getting Started 1 A new fiber should be conditioned following the manufacturer s recommendations A blank run should be made after conditioning to verify that there are no extraneous peaks 2 If the fiber has been properly conditioned and a blank sample shows extraneous peaks these are usually due to siloxanes from the AutoSampler vial septa Figure 1 These peaks may be a problem with trace analysis especially with an FID or a MS To minimize these pe
108. tested in duplicate by extracting standards with increasing concentrations over a range typically between 10 2000 ppm Detection limits and the limits of quantitation were determined from the linear range and based on 3 x S N ratio and 5 x S N ratio respectively The precision of the method was determined by performing a minimum of 7 extractions at one concentration 1000 ppm on one day This experiment was also done in duplicate to verify the results obtained A comparison was done between the precision obtained when extracting from 16 mL vials and 2 mL vials Results and Discussion Solid phase microextraction is based on an equilibrium process rather than an exhaustive extraction Direct sample extraction and headspace extraction under non stirred conditions indicated that equilibrium conditions were attained after 10 minutes Therefore this was chosen as the extraction time This extraction time was also optimal since the total time for the GC analysis is also 10 minutes A chromatogram of the 10 minute extraction of a 1000 ppm aqueous standard is illustrated in Figure 1 The results obtained for precision and linearity are listed in Table 2 The linearity was also determined for both vial sizes Small Vials Large Vials r value Precision LOD LOQ precision LOD RSD _ ppm ppm RSD ppm Methanol Ethanol Acetone Iso propanol n Butanol Table 2 Linearity precision and limits of detection and quantitation The method was found to
109. that is installed in the Combi PAL itself additional features are possible with the optional Cycle Composer software where a PC controls the Combi PAL Note Prior to reading this manual the reader should first read the Combi PAL System User Manual and become familiar with the general operation of the Combi PAL including defining the position of objects and building methods and jobs Combi PAL 3 Procedure for SPME Sampling with the Combi PAL Preparation It is assumed here that chromatographic conditions have been optimized for the analytes i e that an appropriate column temperature program and detector have been selected Injector Insert The injector insert is important in assuring good results when a SPME fiber is desorbed A straight unpacked insert with an inner diameter between 0 75 to 0 80 mm should be used An insert of smaller diameter will not allow the fiber sheath to penetrate the injector Larger inserts 2 4 mm id will result in broadening of early eluting peaks Varian sells SPME inserts for the 1093 injector SPI and for the 1078 1079 injectors Injector Septum The SPME fiber assembly includes a septum piercing protective needle Figure 1 which is a blunt hollow 23 24 gauge tube O fiber support rod protective needle Figure 1 Detail of the fiber assembly In comparison liquid injection into a GC is usually accomplished with a tapered 26 gauge needle Therefore sample introduction with a
110. that volatile compounds used during the manufacturing process are below a particular level in the final product Residual solvents and monomers are normally monitored using gas chromatography with sample introduction by static headspace SHS This note describes the analysis of a polystyrene polymer that was heated for different times and drawn into different shapes during the manufacturing process The manufacturer required that volatiles in the polymer be identified and that differences in the composition of the volatiles resulting from the variations in the process be monitored Laboratory personnel were planning to conduct the analysis using GC MS and SHS however solid phase microextraction SPME was considered as a possible alternative All of the samples were analyzed with SPME and SHS the same compounds were recovered with both techniques However with heated SHS recovery was biased toward the more volatile compounds with SPME at ambient temperatures the recovery tended to be more uniform It was concluded that all of the manufacturer s requirements could be met by sampling the polymer with automated SPME with considerable savings in equipment cost and laboratory space Compound Base lon RT min 1 acrylonitrile 52 5 11 2 t butylbenzene 119 13 44 3 styrene 104 14 34 4 a methylstyrene 117 16 57 5 butylated hydroxytoluene 205 31 35 Figure 1 Total ion chromatogram of headspace over p
111. ting diones after eight minutes the effluent was directed into the ion trap where the later eluting aldehydes as well as various ethyl esters were detected GC injector analytical column N ion trap N auxiliary column Figure 3 Schematic of system for beer analysis The sample is introduced into the GC injector and flows into the ECD where the diones are detected After 8 minutes the valve is activated and directs the sample into the ion trap to detect the aldehydes and esters Another possible approach for combining ECD and ion trap detection would have been to split the effluent between the ECD and the ion trap This was rejected for two reasons 1 It was necessary to keep the ECD at a low temperature to maximize sensitivity If the effluent were split high boiling compounds would have entered the cold ECD causing contamination 2 Splitting the effluent would have decreased sensitivity for all of the compounds Instruments Varian Saturn 2000 GCMS equipped with an ECD and two injectors a SPI and a 1078 A 4 port 1 32 inch high temperature mass spec leak tested Valco valve was mounted in the column oven Automated SPME lll system Varian Genesis static headspace sampler with electroform nickel sample path Column 30 m x 0 25 mm coated with 0 50 um Supelcowax 10 temperature program 50 C 1 minute 5 C min to 200 hold 9 min carrier gas helium 41 cm s at 60 C Two pieces of 35 cm 0 25 mm deactivated fu
112. tion of Flavor Compounds A Comparison of Two Fiber Coatings and a Discussion of the Rules of Thumb for Adsorption Rapid Analysis of Nicotine and Cotinine in Urine Using Headspace Solid Phase Microextraction and Selected lon Monitoring On line Determination of Organochlorine Pesticides in Water by Solid Phase Microextraction and Gas Chromatography with Electron Capture Detection Sampling Volatile Organic Compounds Using A Modified Solid Phase Microextraction Device Quantitative Extraction Using An Internally Cooled Solid Phase Microextraction Device Headspace Solid Phase Microextraction Analysis For Organic Compounds In Environmental Samples By Headspace Solid Phase Microextraction Direct Solid Phase Microextraction Of Complex Aqueous Samples With Hollow Fiber Membrane Protection Solid phase Microextraction A Solvent Free Alternative for Sample Preparation Solid Phase Microextraction REFERENCE J AGRIC FOOD CHEM VOL 42 PP 1925 1930 LC GC 13 11 p 882 Jpn J Forensic Toxicol Vol 13 1 pp 17 24 J High Resolut Chromatogr 19 5 PP 247 256 J HIGH RESOLUT CHROMATOGR19 3 PP 155 60 ANAL CHEM VOL 67 1 PP 34 43 ANAL CHEM VOL 65 14 PP 1843 52 J HIGH RESOLUT CHROMATOGR VOL 16 12 PP 689 92 ANAL COMMUN 33 7 PP 219 221 ANAL CHEM VOL 66 17 PP 844A 854A Anal Chem 66 17 pp 844 A 853A 23 24 03 914835 00 1 SPME Advantage and Application No
113. ts Linearity and precision SHS is a well established technique for this application and SPME is new therefore linearity and precision were demonstrated only for SPME Linearity was demonstrated over the range 0 500 mg dL using aqueous samples Figure 2 1 5 Four replicates at each level PR Response factor RSD 1 697 2 r 0 9999 O a YN o 2 ra 0 100 200 300 400 500 Ethanol mg dL Figure 2 Linearity curve for ethanol in water with SPME sampling 64 03 91483500 1 Precision data was derived from spiking both HPLC water and alcohol free blood with ethanol and then mixing with n propanol internal standard Table 1 RSD Area counts ethanol n propanol RSD ratio 2 16 1 12 1 61 2 99 3 03 0 68 Table 1 Precision data for 10 SPME samplings of spiked water and spiked blood at 160 mg dL Comparison with Static Headspace For comparison of SHS and SPME the following procedure was used Standards 198 uL ethanol was dispensed with a calibrated pipette into a 100 mL volumetric flask the flask was then filled to the mark with HPLC water Conc 156 2 mg dL Samples Blood and urine samples from California drivers Internal standard 20 uL of n propanol was added to 100 mL of HPLC water that was saturated with NaCl Conc 15 8 mg dL Prior to analysis aliquots of sample or standard were diluted ten fold with internal standard Two 1 mL aliquots of this mixture were dispensed into
114. uld spike glass beads with known quantities of these solvents and compare the response to the responses of the solvents in the samples 1 00 0 80 E Sample 1 m Sample 2 OSample 3 El Sample 4 0 60 ds 0 40 0 20 0 00 acrylonitrile t butylbenzene styrene o methylstyrene butylated hydroxytoluene Figure 3 Showing the variation in recovery of various solvents from polymer samples after SPME sampling of the headspace Results are normalized to sample 1 the untreated polymer The other samples were subjected to various heat treatments described above Conclusions SPME offered an attractive alternative to SHS for determining volatiles in polystyrene polymers The automated system costs less and consumes far less laboratory bench space than SHS and the end results suggested that instrument conditions are easier to optimize with SPME Combi PAL 57 References and Additional Reading 1 Automation and Optimization of Solid Phase Microextraction Arthur C L Killam L M Buchholz K D Pawliszyn J and Berg J R Analytical Chemistry 64 1992 pp 1969 66 2 Determination of a Wide Range of Organic Impurities in Water with Automated Solid Phase Microextraction Penton Z
115. ure and analyze the wine samples with headspace sampling and without the addition of salt Headspace Sampling 0 8 mL 30m x 0 25 mm coated with 0 25 um Nukol 40 C hold 6 minutes 5 minute to 180 C hold 3 minutes 20minute to 200 C hold 5 minutes total run time 43 minutes Carrier gas helium 37 cm s at 60 C SPI with SPME insert 200 C isothermal transfer line to mass spec 220 C Electron impact ionization mode mass range 45 170 u ion trap temperature 170 C Chemical ionization mode using acetonitrile as the reagent gas for molecular weight confirmation of the terpene alcohols in the wine samples 230 C range 10 Fibers Supelco Inc were coated with 100 um polydimethylsiloxane PDMS or 85 um polyacrylate SPME headspace 0 8 mL liquid sample in a 2 mL vial SPME liquid 1 2 mL liquid sample in a 2 mL vial In the linearity precision and minimum detection level studies 30 minutes absorption 5 minutes desorption one sampling per vial These sampling times were varied in the preliminary work Samples 10 mL in a 22 mL vial were heated to 70 C valve and transfer line temperatures were initially 85 C but were raised to 170 and 190 C when there was no response at the lower temperatures Equilibration time 10 minutes mixed at 80 of full power 7 minutes stabilization time 2 minutes Sample loop was 500 uL Test sample consisting of purchased terpene alcohol standards Figure 1 at various conc
116. vidual values submitted by each laboratory were calculated the correlation coefficients r varied from 0 8634 to 0 9907 with six of the labs showing a value for r greater than 0 98 With the automated system r was 0 9974 Precision and Relative Response of Automated SPME Compared to Manual SPME In order to compare manual sampling with magnetic stirring and automated sampling and agitation on the same GCMS and with the same samples 1 mL samples at the 30 ppb level were placed in 2 mL vials and sampled both ways With the manual sampling the rotation speed of the stirring bars was increased to the maximum that allowed a smooth rotation in the sampling vials 90 of full capacity Precision and average responses are shown in Table 2 Pesticide Mean Area Counts rsd n 6 Limit of Detection s n 3 Manual SPME Automated SPME with automated SPME ppt Dichlorvos 595 6 8 2068 6 2 1300 EPTC 36678 5 3 118974 3 3 9 Ethophos 6281 16 0 29173 5 0 53 Trifluralin 902449 8 6 1252269 5 0 0 1 Simazine 194 27 5 636 7 2 1400 Propazine 4022 14 9 15912 5 2 92 Diazinon 112938 13 2 311953 5 6 4 5 Methyl chlorpyriphos 186655 12 0 449245 5 3 1 Heptachlor 155441 11 5 186629 7 2 8 5 Aldrin 148538 11 3 207265 6 7 3 7 Metalochlor 25776 18 5 105790 5 3 650 Endrin 88822 17 4 150120 7 4 11 Table 2 Precision and relative responses with automated and manual SPME sampling of 1 mL pesticide samples in 2 mL v
117. was concluded that injecting into a hot injector gives the best results even when the sample contains very volatile analytes such as vinyl chloride Column Cryogenic focusing may be useful to improve the peak shapes of very volatile compounds if the column is not very retentive SPME sampling does not require special GC conditions Peaks tend to be sharper with SPME than with samples introduced using conventional static headspace Is the fiber easily saturated and do compounds tend to be displaced in mixtures This depends on many factors including sample size the affinity of the fiber for the components of a particular sample and the fiber thickness Table 1 shows that benzene gave the same response whether it was the only organic compound in water or in a test mixture containing several other compounds In another experiment there was a linear response to benzene up to concentration ranges greater than 300 ppm Nevertheless it is important in developing and validating a method to do recovery and linearity studies Diluting the sample to a lower concentration will minimize displacement effects 30 03 914835 00 1 Conc ppm MeCl CHCI Benzene TCE Dioxane Toluene Xylene TMB 1 4281 3567 175183 51579 1203 308884 427923 637614 2 8471 6322 337571 101351 2165 617885 872322 1251551 4 17894 12478 704235 207027 4192 1233313 1713901 2331268 1 154458 2 328038 4 674635 Table 1 FID area counts for benzene alone in water at bottom 3 rows an
118. which provides a simple rugged alternative to purge amp trap and conventional GC References and Additional Reading 1 Determination of a Wide Range of Organic Impurities in Water with Solid Phase Microextraction Penton Z Varian GC Application Note 50 2 Analysis of BTEX in Soil with Automated Headspace and PID Jennison Colin amp Joy Varian GC Application Note 45 68 03 91483500 1 0 805 MU um mM Figure 3 SPME headspace sampling of 10 ppm Gasoline in water FID elution time 1 6 minutes Replicates 12 1 1 1 Al 35000 30000 25000 20000 Peak Size 15000 10000 5000 250 500 1750 Amount ppb Figure 4 Calibration curve for Toluene PID 1 ppb to 1 ppm in water Corr coef R is 0 999785 Combi PAL 69 70 03 91483500 1 Determination of Phenols in Water with Automated S P M E SPME and Agitation Varian ERDIFAHDN nn Zelda Penton Varian Chromatography Systems Key Words SPME 8200CX Blood Phenols The extraction of phenols from water was easily accomplished with automated solid phase microextraction SPME The 8200 CX AutoSampler upgraded for automated SPME with agitation was used in the analysis With the new agitation capability the SPME fiber is vibrated during the absorption step This has the effect of disrupting the depleted layer of water that tends to accumulate around the fiber during static sam
119. with a liquid polymeric stationary phase During sampling the coated fiber is exposed directly to the sample 2 or to the headspace above the sample 3 4 allowing absorption of the analytes according to their affinity toward the fiber coating The analytes are thermally desorbed from the fiber in the hot injector of a GC and are subsequently analyzed The fiber can be used immediately for a succeeding analysis Direct and headspace SPME have been successfully applied to the determination of alcohols 5 7 These results were obtained by performing both manual and automated sampling from various matrices Concentrating on the results obtained by headspace analysis the RSD values that were determined ranged between 1 2 10 1 for manual SPME and 0 7 3 0 with automation The target analytes selected for this investigation are listed in Table 1 and a chromatogram is shown on the right SPME Varian Application Note Number 14 1 methanol 3 4 5 2 ethanol 3 acetone 4 2 propanol 5 n butanol 2 1 0 1 2 3 4 5 6 Retention time min Figure 1 Chromatogram of a SPME extraction of a 1000 ppm standard aqueous solution using an 85 um polyacrylate fiber Analyte Formula BP C MW Solubility Volatility Acetone C H O 56 5 58 08 Methanol CH O 64 7 32 04 Ethanol C H O 78 5 46 07 Iso propanol 2 propanol C H O 82 5 60 09 n Butanol C H O 117 118 74 12 miscible very miscible very miscible very

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