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1. Distribution Model AL 350200 Conductivity Detector Service Manual Rev 0 January 1994 SSI Distribution 349 North Science Park Road State College PA 16803 USA 814 234 8180 800 525 6163 Fax 814 238 6072 Model AL 350200 Conductivity Detector Service Manual 1 INTRODUCTION About the Conductivity Detector ohio cid per ea a Ye ne ad ba ceed suasesmouy teas os Re dun 3 What the Conductivity Detector Includes eene 3 PECTIN IC ALONG ead oce tees db uude ure te ceut e E aptat citus etd cape coil 3 Principle Of Operation see eon eet ee GN UG Di cae E d 4 2 INSTALLATION AV Hato You Wall Need aeo eet e heb rco enit recent edle Saas aaa 4 WN PAC King adie E 5 Controls and Feature Sinang i Bas i ee 5 6 Fl id Connections Soe toe cas durent oec iom a aaa a a E s Ei aa eai cec 7 Plectrital COBDECHOHS 45 5 eee eda ee 7 Voltage Selection cei eh beat ei eb aiian as asia 7 Fuse Replacement ys ei eran aa a E aA ES Ah 8 Equi bration sc Set os xia Paces Beebe Peptsert icta arces apa oin dod ote sate esee Ru eS Ga een 8 Initial Adjustment eoi itecto tea sete R ibo tecta ase 8 Remote Operation sssrinin E P 8 IRCTIOLE PAULO ZC e echoed ce E a E A EE hae lane E OE 9 3 ROUTINE OPERATION Warm up I PE 9 RTGS CURT GS siue potete dtt yates guste eri quadr ive dev Maie citet EI EEEE aaa eeens 9 Changing Temperature Set POLI uode uir oer cdi ee teh po
2. turn on just at the point you want Figure 3 1 10 4 MAINTENANCE amp TROUBLESHOOTING Routine Maintenance Because of its simple rugged design the Conductivity Detector does not require maintenance or service on a routine basis This section deals with the solutions to a few problems which may arise in routine operation Even a very small leak can cause baseline noise Approximately once a month inspect the interior of the cell compartment for signs of leakage 2 A noisy baseline characterized by rapid noise spikes is most often the result of air bubbles in the cell as shown in Figure 4 2 This situation typically occurs on initial operation of a new column or an unused column which has been allowed to dry out The only remedy is time 20 45 minutes for the trapped air bubbles to be purged from the cell If the problem persists for more than 45 minutes boil approximately 250 mL of deionized water and remove the columns from you
3. 1 4 4 temperature is close Baseline Noise Due to Air to 30 C try Bubbles in the Cell operating at higher temperature equilibrate valves etc 4 Column Regenerate column contamination follow manufacturer s procedure eee eS ee eee Noise Baseline 1 Trapped air See step 2 under Figure 4 2 bubbles shown MAINTENANCE in Figure 4 2 section Baseline Noise Due to Pump Flow 2 Pump flow Shut off pump If shown in baseline is quiet Figure 4 3 then service pump per manufacturer s recommendation 3 Cell Shut off pump If a at 0 5 mL min contamination noise persists clean or replace cell 4 Column Regenerate or change column Degas eluant 6 Temperature as Insulate column b at 1 0 mL min shown in Figure 4 4 Figure 4 3 Peak Shape 1 Overload Reduce sample size p Regenerate column Baseline Noise Due to Replace guard Temperature Fluctuations 4 Dead volume Check column guard connections Retention Time 1 Pump Service pump per manufacturer s recommendation Figure 4 4 12 Detector Problems Physical Problems Unable to Zero 1 Offset by offset Adjust offset knob Leak at 1 Loose fittings Tighten fittings knob Bulkhead Union 2 Eluant New eluant 2 Old ferrule Replace ferrule conductivity too 3 Wrong ferrule Replace ferrule high 4 Damaged Replace bulkhead 3 Electronic failure bulkhead union union No Power 1 Line unplugged Plug in power line 2 Blown fuse Replace fuse 3 Elect
4. RS 232 port is identified by either COMI or COM2 Make the connection between the computer port and the detector port using either the RS 232 cable with 25 pin on both ends or the RS 232 cable with 25 pin and 9 pin Make sure you turn the computer and the detector off before making this connection After making this connection you can control the detector functions through your data system with a suitable program Customized Programming Experience in a programming language such as C or Basic is a prerequisite to writing a customized program for the RS 232 port PROGRAMMING PARAMETERS BAUD RATE 2400 others available upon request WORD FORMAT one start bit 0 eight data bits x and a stop bit 1 PARITY NONE PIN SET UP 2 RxD receive data from the computer 3 TxD transmit data to the computer T GND ground 11 Remote autozero 12 13 24 25 Reserved remote control by TTL logic signal Remote Autozero The Autozero function may be triggered from a non RS 232 device using either a contact closure or TTL signal and the remote autozero cable included in the accessory kit Connect the remote autozero cable to the RS 232 port on the back of the detector Attach the two leads on the other end of the cable to the appropriate connectors on the remote device Both contact closure and TTL signals will initiate the autozero function as described below Contact Closure The autozero function is initia
5. Switches AC power to detector ON OFF 2 Electrical Power Line 115 220V AC 50 60 Hz 100 Watts field selectable 3 Signal Output Range Select Switch Selects 0 1 V or 0 10 mV full scale detector output 4 Signal Output Connection Connects Conductivity Detector to recorder or data system 5 RS 232 PORT Remote operation of detector functions 6 Integrator Offset Knob Used to adjust the signal output after the autozero is activated Some integrators cannot accept negative offsets NOTE This knob will also offset the value adjusted during the conductivity measurement and electronic calibration check See page 11 for details Figure 2 2 Back Panel Exterior Interior Figure 2 3 1 Conductivity Cell Cell Heater The cell compartment is located behind the removable plate which contains 2 of insulation Access is obtained by pulling the plate forward after the chrome plated screws have been released The cell compartment contains a knitted TFE tubing heat exchanger 2 Detector Electronics PC Board Figure 2 3 Interior Fluid Connections Using the metal free compression screw nut and ferrule provided with the Conductivity Detector connect a length of 1 16 OD x 010 or 007 ID tubing between the column outlet and the detector Inlet Bulkhead Union Minimize the ID and the length of tubing between the column to the detector to avoid peak broadening Use a 1 4 inch open end wrench to t
6. electrical noise allowing stable operations at very high sensitivity ranges Ten ranges from 0 1 to 5000uS cm makes the Conductivity Detector compatible with all current IC methods including ultra trace level applications The Conductivity Detector utilizes a temperature controlled cell housing for enhanced baseline stability The heater maintains the cell at a preset temperature and preheats column effluent to minimize thermally induced noise and drift The Conductivity Detector is equipped with a RS 232 serial communication port for remote operation of the detector functions The Conductivity Detector includes e a temperature controlled cell housing to maintain baseline stability regardless of variations in ambient temperature e ahigh sensitivity microprocessor based electrical conductivity detector with low dead volume flow cell and electronic background correction Specifications Electrical Electronic Power 110 220V AC 50 60 Hz 100 Watts field selectable Data Analog Output 0 1 V DC or 0 10 mV DC selectable Computer Interface RS 232 serial communication Fluid Path Construction All wetted parts are of inert polymers PEEK polyetherether ketone and TFE Cell Compartment Insulation Minimum 1 all sides Temperature Control Type 50W DC heating element vulcanized to aluminum block Oven Size 2 7 W x 2 45 H x 6 2 L Nominal Temperature Factory set at 35 C user adjustable Overtempe
7. mm If the detector does not meet these specifications it must be returned to the distributor 19 Instrument Model AL 350200 Conductivity Detector Serial Number INSTRUMENT QUALITY ASSURANCE TEST Performance Test Method Mobile phase Flow rate Range 10 uS FS Polarity Time constant Mode of operation Sample Injection volume Actual Peak area Calibration Value Electronic Range Mode of operation Digital display reading 1 mM sodium acetate in 95 5 methanol water 0 5 mL min Positive Slow Measure 15 ppm sodium nitrate in mobile phase 20 uL Specification gt 90 000 100 Calibrate Conductivity Measurement Temperature Range Mode of operation KCI solution Tested by 35 500 Background 447 1 uS cm at 25 C 20 Date Sensitivity Test Method Mobile phase Flow rate Range Polarity Time constant Mode of operation Data sys attenuation Actual Drift cm min Noise cm min Polarity Time constant Polarity Time constant Lot 1 mM sodium acetate in 95 5 methanol water 1 mL min 10 uS FS Positive Slow Measure 8 mV FS Specification 0 1 cm min 5mm Fast Fast 21
8. the column Clean or replace the column 4 Use the following procedure to differentiate electronic problems from flow related problems 4 Pass distilled deionized water through the detector cell The water must have a resistant of 18 megaohm a Turn the integrator offset knob all the way or higher Use the integrator offset knob located at the counterclockwise facing the back of the back of the Conductivity Detector to zero the digital detector Press the CALIBRATE key the range display do not use the AUTOZERO key Failure to should automatically go to 100 uS cm As this is properly zero the display will lead to erroneous accomplished the numbers 000 through 999 are readings sequentially displayed verifying display function and detector gain settings The final display 5 Pass the unknown conductance solution through the value should read between 99 5 and 100 5 See detector Move the Range up or down until the Electronic Calibration Check for details conductivity reading is on scale The display reads conductivity in uS cm full scale range b Place detector in MEASURE position and RANGE in 5000 uS cm The unit should have a 6 The detector is factory calibrated with known conductivity reading The number is not conductance standards The detector may be important but the reading should be On Scale recalibrated using the procedure in Appendix C c Change RANGE to a lower value and observe if Note The conductivity measuremen
9. L in The injector can be bypassed Set the polarity to and the time constant to fast Set the range to 500 Zero the reading on the display using the integrator offset knob located at the back of the detector not the AUTOZERO key Pass 447 1 uS cm conductivity solution at a flow rate of 2 0 mL min Once the reading stabilizes reduce the flow rate to 0 5 mL min Record the lot number for the solution on the QC sheet Wait a few minutes until the reading stabilizes The meter should read 89 4 89 4 100 x 500 447 1 uS cm If necessary adjust the blue POT 1 until the display reads 89 4 18 ELECTRONIC TEST 1 Turn the integrator offset knob all the wan counterclockwise facing the back of the instrument Set the detector to CALIBRATE mode It should automatically switch to range 100 The display should read 100 0 5 If the number is higher or lower adjust the yellow POT R60 to read 100 2 Record this reading on the QC sheet PERFORMANCE TESTS Start the pump with 1 mM sodium acetate in 95 5 methanol water at a flow rate of 1 0 mL min Let the system equilibrate until baseline stabilizes Adjust the back pressure regulator so the pump reads 250 psig A Noise and drift test 1 Set the detector as follows Range 5 Polarity Positive Time constant Slow Mode of operation Measure 2 Set the ChromJet Integrator as follows Attenuation 0 5 Chart speed 0 5 PT 200 PW 12 OF 20 3 Press AUTOZERO o
10. der Cable RS 232 Cable with 25 pin on both ends RS 232 Cable with 25 pin and 9 pin Remote Autozero Cable 15 Appendix C Conductivity Calibration Procedure for the Conductivity Detector The Conductivity Detector s primary function is detecting ionic species in chromatography applications However it can be used as a conductivity meter to measure the absolute conductance of a unknown solution The detector is factory calibrated to read absolute conductance but may be recalibrated using the following procedure 1 10 Remove the detector cover by unscrewing the four screws on the sides of the detector Locate gain potentiometer POT 1 on the PC board Figure 3 1 Set the polarity to and the time constant to fast Place the detector into BACKGROUND mode by depressing the BACKGROUND key Set the Range to match the expected conductance value of your standard Pass distilled deionized water through the detector cell The water must have a resistant of 18 megaohms or higher Use the integrator offset knob located at the back of the detector to zero the digital display do not use the AUTOZERO key Pass a known conductance solution through the detector The display reads conductivity in uS cm full scale range If the conductivity reading is different from the actual conductance of your standard solution adjust the gain potentiometer POT 1 with a small screw driver until the corr
11. dre ede 9 Changing Overteniperature Set Point atu iaa 9 4 MAINTENANCE AND TROUBLESHOOTING Route Mantena ce ou ecootenidolaestona pecluo cayo dcdtes cd oi c a e Lace auae 10 Measuring Absolute Conductivity eese eene eene enne 10 Electronic Calibration Check oo o Teide re apu versa ch eodite tula verint aS 10 Troubleshooting CM Aarts ees toss coo t oc beet aeui uiu e p IP wae 12 13 5 APPENDICES A Standard AGCeSSOHGS II iiic cnivetet eost qni bes eroi bored cb au e deber dox een OET 14 B Replacement spare Partsz uicem tuin dE di fa a eU pde MS 15 C Conductivity Calibration Procedure seen 16 D Electronic Calibration Procedure sete ices tease dice aspen alte dear SOR oae Sadie 17 Es OC Proce dure e Crete ceteri E er T veste ete reae ERU 18 19 BLOCK DIAGRAM 5 4teistssocsbtteston aima titalestetan olas vrina etatis 21 1 INTRODUCTION About the Conductivity Detector The Conductivity Detector can be interfaced with any HPLC or IC pumping system to provide high sensitivity detection of charged substances The Conductivity Detector utilizes a high frequency 3 KHz sinusoidal applied potential and synchronous detector to measure minute changes in conductance of the column effluent A one touch background suppression circuit provides electronic compensation for the conductivity of the eluant bringing the baseline to electrical zero Advanced microprocessor based circuit design reduces extraneous
12. e Conductivity Detector Conductivity Conductivity Time Constant Slow Polarity for Anions for Cations Background Background Position Range 100uS cm on 2 With recorder or data collection system ON note noise and slope of baseline for a 5 10 minute period 3 When the baseline is stable i e no drift depress the MEASURE key 4 Set RANGE to desired operating range Range 10 is suitable for most applications 5 Depress AUTOZERO Background Eluant conductivity is now subtracted This procedure can be repeated as often as necessary NOTE Because the Conductivity Detector s autozero circuit resets the zero to within 2 of true zero it is possible to have a baseline at a slightly negative potential 6 Some integrators can not conveniently handle negative offset In this case the integrator offset knob located on the back of the detector can be used to bring the signal output up to a positive value Remote Operation RS 232 Serial Communication Port The RS 232 port provides remote operation of the detector functions or digital transmission of the detector signal The RS 232 port is a 25 pin socket located on the back side of the detector The RS 232 port on your computer will have the 25 pin or a 9 pin configuration Your computer may have other ports such as game printer and application ports which may have the same configuration Make sure you find the correct RS 232 type port On the IBM PC the
13. ect reading is displayed Repeat step 6 The reading should return to zero Otherwise repeat step 6 through 8 until stable consistent readings are obtained Verify detector electronics calibration using the Electronic Calibration Check procedure described in this manual If the value is outside the established range recalibrate the electronics using the procedure in Appendix D 16 NOTE The conductivity measurement will change if the integrator offset knob is changed from the position set in step 7 leading to erroneous results Appendix D Electronic Calibration Procedure for the Conductivity Detector Detector electronics are factory calibrated before shipping You can check the electronic and verify its stability using the Electronic Calibration Check procedure described in this manual Should the calibrate value fall outside the acceptable range you may recalibrate the detector using the following procedure 1 Remove the detector cover by unscrewing the four screws on the sides of the detector 2 Locate potentiometer POT R60 on the PC board Figure 3 1 3 Set the polarity to and the time constant to fast 4 Turn the integrator offset knob located at the back of the Conductivity Detector all the way counter clockwise facing the back of the detector 5 Depress the CALIBRATE key The range will switch automatically to 100 uS cm As this is accomplished the numbers 000 through 999 are seq
14. ernal resistance The ionic species in chromatography applications However final display value should read between 99 5 and it can be used as a conductivity meter to measure the 100 5 If the displayed value is outside this range the absolute conductance of a solution using the following detector electronics should be recalibrated using the procedure procedure in Appendix D Alternately the detector may be returned to your distributor for recalibration 1 Place the detector into BACKGROUND mode by depressing the BACKGROUND key NOTE The calibrate value will change if the integrator offset knob is moved from the fully 2 Set the polarity to and the time constant to fast counterclockwise position set in step 2 This is normal and does not indicate detector malfunction 3 Set the Range to match the expected conductance value of your unknown If you are not sure pass the unknown conductance solution through the detector and move the Range up or down until the conductivity reading is on scale 11 Troubleshooting Charts gt Example of Baseline Drift y The following charts summarize possible problems that can be encountered during operation of the Conductivity Detector the causes of those problems and the most effective remedies Chromatographic Problems Symptom Figure 4 1 Baseline Drifts 1 Temperature as Allow system to as shown in shown in Figure equilibrate if room g Figure 4
15. es of operation Working Mode and Display Mode The Working Mode includes CALIBRATE BACKGROUND and MEASURE The CALIBRATE mode is used to calibrate the electronic and verifies its stability See page 11 for details The BACKGROUND mode is used to measure the absolute conductivity of the eluant or any solution that flows through the detector cell In this mode of operation the autozero is disabled therefore the current signal is the actual conductance of the solution in the cell In this mode the Conductivity Detector can be used as a conductivity meter See page 11 for details The MEASURE mode is used to measure conductivity with baseline subtracted The current resulting from the eluant conductivity no sample present is subtracted by the autozero circuitry The Display Mode includes CONDUCTIVITY TEMPERATURE and TEMPERATURE SET The LED on the Conductivity Detector can be used to display any of these modes In CONDUCTIVITY mode the LED displays the conductance of a solution in uS cm full scale range In the TEMPERATURE mode the LED displays the actual temperature of the cell compartment in C In the TEMPERATURE SET mode the LED displays the cell temperature set point This mode can be accessed by pressing the TEMP TEMP SET key twice until the display blinks See page 9 for details The Conductivity Detector uses a microprocessor to control the autozero process During the autozero process the conductance detected by the cell i
16. g mode to MEASURE 3 Activate AUTOZERO When autozero light goes out unit is ready The AUTOZERO function rapidly offsets the eluant background conductivity Depress the AUTOZERO switch before each injection to insure baseline correction Changing Temperature Set Point The Conductivity Detector utilizes a temperature controlled cell housing for enhanced baseline stability The temperature set point has been set at 35 C during manufacturing The temperature controlled cell can be adjusted to within 0 1 C of any temperature between ambient temperature and 80 C The current cell temperature can be read directly from the digital display on the front of the detector by selecting temperature with the TEMP TEMP SET key once To change the temperature set point depress the TEMP TEMP SET key twice The temperature reading will flash Increase or decrease the temperature set point by depressing the UP or DOWN arrows on the RANGE key NOTE The overtemperature control circuit on the Conductivity Detector is preset at the factory to 60 C If the operating temperature is to be reset above 60 C first reset the overtemperature set point see the following section Changing Overtemperature Set Point When a change has been made to the cell heater temperature set point the overtemperature set point may need to be adjusted The overtemperature has been set at 60 C Adjust the overtemperature set point to approximately 20 C higher tha
17. ighten the compression screw nut and ferrule slightly past finger tight Do not overtighten Using the metal free compression screw nut and ferrule provided with the Conductivity Detector connect a length of 1 16 OD tubing to the detector Outlet Bulkhead Union The open end of the tubing may be used to direct detector effluent to waste or an auxiliary detector Electrical Connections Recorder Data System Connection Connect the signal output from the Conductivity Detector back panel to the signal input from your recorder or data system Because the Conductivity Detector is capable of driving to greater than nominal full scale voltages we recommend that the Conductivity Detector output range be set to 0 10 mV in most applications Follow the data system instructions to configure the system for 0 10 mV full scale signal input If your recorder or data system will not operate at the 0 10 mV setting set the output range switch to 0 1 V full scale B SEIN ES H DES k E X EN E Figure 2 4 s tov 0 USE ONLY WITH 120v O 250V FUSES 220V O 240V O N DISCONNECT POWER BEFORE REPLACING FUSES Power Connection Plug the modular power cord provided with the accessory kit into the power connector on the rear panel of the detector The voltage is field selectable for operation at 100V 110V U S standard
18. int when the display blinks 2 Conductivity Reads conductivity in uS cm full scale 3 Measure Reads changes in cell conductance with background correction 4 Background Reads absolute cell conductance with no background correction 5 Calibrate Calibrates electronic circuitry and verifies its stability See page 11 for details 6 Recorder Output Time Constant Fast 0 2 sec or Slow 1 sec 7 Recorder Output Polarity or 8 Temperature Set Reads the actual cell temperature in C or when depressed twice until the display blinks shows the cell temperature set point in C 9 Autozero Control Digitally offsets the background conductance while in the MEASURE mode 10 Range Selection Display Displays selected range 11 UP and DOWN Changes the operating range while in the CONDUCTIVITY mode or the cell temperature set point while in the TEMPERATURE SET mode 12 Heater Indicator Lit when power is applied to heater When system is at thermal equilibrium indicator will flash briefly 13 Heater Overtemperature Lit when cell temperature exceeds the overtemperature set point 14 Detector Inlet Line A bulkhead union accepts 1 16 OD tubing for connection to column outlet 15 Detector Outlet Line A bulkhead union accepts 1 16 OD tubing for connection to additional detectors or waste bottles on Figure 2 1 Front Panel Exterior Back Panel Exterior Figure 2 2 T Power
19. n both the detector and integrator Adjust offset of the detector if necessary 4 Trace the baseline for one hour Save the baseline trace for drift and noise evaluation 5 Calculate drift Beginning after 15 minutes of the one hour run measure the baseline drift for 15 minutes 7 5 cm Report the drift in cm min Refer to Figure 1 as an example 6 Calculate noise Within the 15 minute section used for the drift measurement pick 5 points randomly Measure the short term noise using the contact scale and report the average noise in mm B Sensitivity test 1 Set the detector as follows Range 5 Polarity Positive Time constant Slow Mode of operation Measure 2 Set the ChromJet Integrator as follows Attenuation 0 5 Chart speed 2 PT 200 PW 12 OF 20 Baseline drawing Yes 3 Set the pump flow rate to 0 5 mL min 4 Press AUTOZERO on both the detector and integrator Adjust the offset of the detector if necessary 5 Inject 20 uL of the standard 6 Repeat the injection 4 more times and record the peak areas 7 Report the peak area as the average of the five injections NOTE If the peak area is less than 80 000 it may change later depending on the results of the first few detectors adjustments to the sensitivity must be made Adjustment procedures will be covered later SPECIFICATIONS The detector must meet these specifications Sensitivity gt 80 000 Drift 0 1 cm min Noise 3 0
20. n the heater temperature set point The overtemperature control circuit provides an external means of protecting your equipment When the cell temperature reaches the overtemperature set point the overtemperature light will turn on and the heater will be turned off The overtemperature set point can be set by adjusting POT P1 To adjust the overtemperature set point 1 Remove the cover of the detector and locate the POT P1 and the test point TP1 They are located at the corner of the PC board Figure 3 1 2 UseaDC voltage meter to measure the voltage at TP1 10 mV corresponds to 1 C If you want to set the overtemperature set point to 60 C the voltage at TP1 should be 600 mV Adjust POT P1 to get the correct voltage Turning P1 clockwise will decrease the overtemperature set point Likewise turning P1 counterclockwise will increase the overtemperature set point If you do not have a DC voltage meter you can still adjust the overtemperature set point Set the cell temperature set point so that it is higher than the desired overtemperature set point Example If you want to set the overtemperature set point at 60 C then set the cell temperature set point gt 60 C Wait for the cell temperature to reach the expected overtemperature set point Then adjust P1 until the overtemperature light turns on You can hear a relay click which turns off the heater You can adjust P1 back and forth to get the overtemperature light to
21. or 220V or 240V European Standard Caution Operation at the wrong input voltage may damage the detector Voltage Selection Unplug the power cord from the power source Insert the blade of a small screwdriver into the slot next to the power connector and gently pry open the fuse block Pull the fuse block straight out Use tweezers or a pair of needle nose pliers to pull the voltage selector card straight out Figure 2 4 Position the plastic voltage selector for the appropriate voltage as indicated in Figure 2 5 Press the voltage selector back into place Fuse Replacement Two types of fuses are provided with the Accessory Kit When changing the fuse be careful to use the appropriate voltage fuse One 1 5 Amp slo blo fuse is required for 120V operation Two 1 0 Amp slo blo fuses are required for 240V operation Equilibration Switch on the Conductivity Detector Allow the components to warm up until the operating temperature is reached The cell temperature has been preset at 35 C The cell temperature can be monitored from the digital display on the front of the detector To monitor the cell temperature depress the TEMPERATURE key Initially the cell heater light will glow continuously indicating the cell has not yet reached operating temperature When operating temperature is reached the heater lamp will dim slightly Initial Adjustment 1 Set the following by depressing the corresponding membrane keys on th
22. r system Pass circulate the boiled water through the cell for a few hours Persistent problems with air bubbles may be caused by failure to degas eluants properly Most eluants can be degassed by filtering through a 0 2 micron membrane filter under vacuum by sonication in an ultrasonic bath or by helium sparging Bubble formation in the cell can be minimized by attaching a restrictor approx 1m of 1 16 OD x 0 01 ID tubing to the detector bulkhead union outlet Conductivity Detector cells are leak tested to 500 psig Irregular noise may be due to contamination of the cell with organic material leached from a column or precipitated from a sample Flushing the cell with isopropyl alcohol or similar polar organic solvent often solves baseline noise problems stemming from this cause 3 Irregular noise that does not respond to cell cleaning as described above may be due to flow irregularities in the pumping system or to impurities leaching from the column To check this possibility shut the pumping system OFF and allow 5 minutes or so for the baseline to stabilize at a new level If the no flow baseline is noise free assume the problem stems from the column from the eluant or from the pump rather than from the Conductivity Detector To check if the problem is due to the column remove the column including guard column and pump the eluant directly through the cell Pump pulsation may appear If the noise stops the problem must be from
23. rature Protection Factory set at 60 C user adjustable Precision 0 05 C Heat Exchanger Non metal TFE tubing knitted and encased in high thermal mass housing Detector Type Alternating current Synchronous Detection 3 KHz Frequency Range 10 switchable 0 1 0 5 1 5 10 50 100 500 1000 5000 uS cm Noise Less than 0 0025 uS cm Drift Less than 0 03 u S cm hour Autozero Offsets background signal up to 10 000 uS cm Cell Type 2 electrode gold plated 0 5 uL volume mounted vertically Display 4 Digit LED Display in Six Modes Working Modes a Calibrate Test Reading of 100 uS cm with 10 step gain test b Background Absolute conductivity of eluant c Measure Conductivity with background offset Display Modes a Conductivity Conductivity in uS cm b Temperature Actual cell temperature in C c Temperature Set Cell temperature set point in C Principle of Operation The Conductivity Detector measures the AC conductance of a liquid sample across two gold plated electrodes which are separated by an insulator A 3 KHz oscillator is used to eliminate any polarization of electrodes The detector ranges from 0 1 to 5000 uS cm and is recorded by an external recorder or data system through an analog signal output The Conductivity Detector has a new microprocessor circuit that improves detection sensitivity by reducing baseline noise and drift The Conductivity Detector has 6 settings in two separate mod
24. ronic failure Physical Problems Symptom Overtemp 1 Cell Cell Temperature Control Problems Lamp Lit temperature above overtemp No Power serpoint 2 Overtemperature Reset over set point below temperature set Not Heating cell temperature pon 2 Cooling down to Wait set p ont lower temp 3 Fluid leak Tighten fitting 3 Electronic failure 4 Er Full Heat 1 Warming up to Wait S higher temp 2 Electronic failure Contact distributor Controlled Temp 1 Failed power up Press calibrate key to does not Match self calibration recalibrate detector Temp Set Point 13 3 APPENDICES Appendix A Standard accessories for Conductivity Detector The following are included in the accessory kit e 1 5 Amp Slo Blo Fuse 120V e 1 0 Amp Slo Blo Fuse 240V Power cord 115 Vac e PEEK nuts pkg 5 e 1 16 x 0 007 ID PEEK tubing 800 psig 10 ft e PEEK double ferrules pkg 5 Remote autozero cable 14 Appendix B Replacement amp spare parts for Conductivity Detector Part No Tubing 011278 Fittings 060149 060108 060100 060146 Miscellaneous AL 320103 AL 320204 AL 23010701 AL 350400 AL 350401 AL 350402 Description Tubing 1 16 OD x 010 ID PEEK Bioclean 5 ft E Z Grip nut 1 16 10 32 CPI seat PEEK Bioclean pkg 10 E Z Grip ferrule 1 16 PEEK Bioclean Pkg 10 PEEK 1 16 Coupling PEEK 1 16 Bulkhead Union Assembly Heat Exchanger Assembly Cell Assembly Recor
25. s sampled processed and memorized During normal operation the memorized data is converted to analog signals to substract the baseline of the eluant A special algorithm is used for fast and accurate baseline subtraction Depending on the magnitude noise and drift of the eluant conductance the autozero process will be completed in 2 3 seconds The microprocessor is also used to simplify the keypad operations of the detector Most functions can be completed by pressing only one key For example no matter what the mode the Conductivity Detector is in when the autozero key is depressed the microprocessor will automatically set its mode in MEASURE and resume the latest range setting and start the autozero process The microprocessor monitors the RS 232 port All keypad functions are accessible through the RS 232 port 2 INSTALLATION What You Will Need In addition to the Conductivity Detector itself you will need the following for installation of a complete chromatographic system Components e An HPLC pump capable of low pulsation solvent delivery at flow rates ranging from 0 5 to 4 0 mL min against pressures up to 3 000 psig For best results with minimal metal contamination we recommend the Series III Bioclean HPLC pump A strip chart recorder or data system capable of accepting analog voltage data Either 0 10 mV or 0 1 V systems can be used For low level anion analysis you may require a suppressor device to s
26. t will change conductivity reading increases leading to erroneous results if the integrator offset knob is changed from the position set in step 4 d Activate AUTOZERO Reading should go to Zero Electronic Calibration Check 5 Each time the Conductivity Detector turns on the microprocessor conducts a self calibration procedure The Conductivity Detector electronics are calibrated If the self calibration procedure fails the detector may before shipping Verify calibration stability using the behave erratically i e temperature control does not following procedure respond etc Should this occur depressing the AUTOZERO or the CALIBRATE key will remedy 1 Set the polarity to and the time constant to fast the problem 2 Turn the integrator offset knob located at the back of NOTE If the instrument fails to respond to the above the Conductivity Detector all the way counter tests you should assume that the problem is an clockwise facing the back of the detector electronic failure within the detector Contact your distributor for assistance 3 Depress the CALIBRATE key The range will switch automatically to 100 uS cm As this is accomplished the numbers 000 through 999 are sequentially Measuring Absolute Conductivity displayed verifying display function and detector gain settings The circuit then measures and displays The Conductivity Detector s primary function is detecting conductivity through a fixed int
27. ted when a contact closure occurs TTL The autozero function is initiated when the TTL signal goes from high to low An open collector device should be used or the front panel autozero key may not function CAUTION Do not apply signals outside the normal TTL range or detector damage may occur 3 ROUTINE OPERATION Warm up Time Normally the detector electronics should be left ON at all times If this has been done the system should be allowed to equilibrate for approximately 30 minutes with eluant flowing This will allow complete equilibration of the column with the eluant If the system has been switched OFF the system should be allowed to warm up to thermal stability This normally takes between 20 to 30 minutes depending on your room temperature at the preset temperature of 35 C It may take longer if the operating temperature has been changed to a higher level or if the starting temperature of the Conductivity Detector is significantly below normal room temperature To monitor the cell temperature depress the TEMP TEMP SET key and read the value on the Digital Display Once operating temperature is reached the cell heater light on the front panel of the detector will dim slightly Initial Settings After the system has equilibrated check for desired operating range and reset autozero corrections as follows 1 Set the RANGE to the desired value Range 10 is suitable for most IC applications 2 Setthe operatin
28. uentially displayed verifying display function and detector gain settings The circuit then measures and displays conductivity through a fixed internal resistance Adjust the potentiometer POT R60 with a small screw driver until the display reads between 99 5 and 100 5 NOTE The calibrate value will change if the integrator offset knob is moved form the fully counterclockwise position set in step 4 This is normal and does not indicate detector malfunction 17 Appendix E Quality Control Procedure Note The same equipment and lab environment must be used for this test EQUIPMENT A Series III HPLC pump B Injector with 20 uL sample loop C Injection syringe D Back pressure regulator E Chromyet integrator REAGENTS A Eluant 1 mM sodium acetate in 95 5 methanol water B Standard 15 ppm sodium nitrate in eluant C Conductivity measurement 1 000 uS cm conductivity solution prepare by diluting the 10 000 uS cm solution 10 x with DI water CONDUCTIVITY MEASUREMENT TEST 1 Connect the conductivity detector to the appropriate voltage 110 or 220V Turn the detector on Check the temperature reading on the front panel The factory set temperature is 35 C If the display is not stable at 35 C see operating manual to change the set temperature Set the detector into BACKGROUND mode Pass water through the detector at a flow rate of 2 mL min After the reading stabilizes reduce the flow rate to 0 5 m
29. uppress the eluant conductivity We recommend the Model 335 Solid Phase Chemical Suppressor e An injection valve or autosampler A column capable of separating the components of interest If you are uncertain as to which type of column to use contact your distributor for assistance To ensure minimum metal contamination we recommend metal free columns A guard cartridge or column compatible with the separation column used Guard cartridges are not required for operation but we strongly recommend their use to prolong separation column lifetime Tools e An open end wrench accommodating 5 16 and 1 4 inch fittings Other e Solvent reservoirs inlet filters chart paper pens etc required for pump and data recorder operation Consult the appropriate instruction manuals for requirements Unpacking The Conductivity Detector along with the power cord and standard accessories are shipped in the same box Before attempting to operate the detector unpack it carefully Do not discard any packing material until you have carefully checked the detector and the accessories kit A complete list of the accessories for the Conductivity Detector is given in Appendix A If you find any evidence of damage to the unit or to the box contact the shipping company that delivered the unit to file a claim Controls Front Panel Exterior Figure 2 1 1 Digital Display Displays conductivity cell temperature or temperature set po

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