Agilent 6890N Gas Chromatograph Troubleshooting Manual
Contents
1. Check all gas trap indicators and dates Verify the gas purity Check for supply tubing and fitting contamination If you suspect that there is contamination in the inlet column or detector perform the bakeout procedure Verify that the oven program temperature and time are sufficient for the samples being injected Check the solvent level in the ALS wash bottles Replace the ALS syringe if necessary Check the sample injection volume Install an Agilent column backflush system Troubleshooting Chromatographic Symptoms Larger Peaks Than Expected Troubleshooting Check each configured column s dimensions against the actual column dimensions See Configurable Items to Always Keep Current Check the autosampler injection volume Check the vial caps Check configured syringe size Some syringe sizes are 3 specified at half capacity If the maximum syringe volume is marked at half height on the barrel not at the top of the barrel enter twice the labeled volume when configuring the syringe size 25 3 Chromatographic Symptoms Peaks Not Displayed No Peaks 26 e If using an autosampler Ensure that there is sample in the vial Verify that the ALS plunger carriage is secured to the syringe plunger Check that the syringe is installed correctly and draws sample Verify that the turret tray is loaded correctly and injections are not from out of sequence vials Watch to see that2. as applicable and column connection See Checking for Leaks e Check sample level in vials e Run replicates of known standards to verify the problem e Consider if this is this first run Has the GC stabilized Troubleshooting 23 3 Contamination or Carryover 24 Chromatographic Symptoms If your output has contamination or unexpected peaks do the following Isolate the source 1 Perform a solvent blank run using a new pure source of solvent If the contamination disappears the problem may be either in the sample or solvent related Perform a blank run remove the syringe from the injector and start a run If the contamination disappears the problem is in the syringe Remove the column from the detector and cap the detector fitting Perform another blank run If the contamination disappears the problem is in the inlet or column If the contamination remains the problem is in the detector Check possible causes all inlet and detector combinations Check the septum type and installation Perform complete inlet maintenance Replace all consumable parts and bake out the inlet Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed Check for sample carryover from previous runs Make several no injection blank runs and see if the ghost peaks go away or get smaller Check the septum purge flow
3. gt 101150234 Agilent 6890N Gas Chromatograph Troubleshooting ee Agilent Technologies Notices Agilent Technologies Inc 2007 No part of this manual may be reproduced in any form or by any means including electronic storage and retrieval or transla tion into a foreign language without prior agreement and written consent from Agi lent Technologies Inc as governed by United States and international copyright laws Manual Part Number 61530 90011 Edition March 2007 Printed in USA Agilent Technologies Inc 2850 Centerville Road Wilmington DE 19808 1610 USA HELER Lig ERAAN Meth BAR KAS PR RCRA KKKAIG 800 820 3278 Warranty The material contained in this docu ment is provided as is and is sub ject to being changed without notice in future editions Further to the max imum extent permitted by applicable law Agilent disclaims all warranties either express or implied with regard to this manual and any information contained herein including but not limited to the implied warranties of merchantability and fitness for a par ticular purpose Agilent shall not be liable for errors or for incidental or consequential damages in connection with the furnishing use or perfor mance of this document or of any information contained herein Should Agilent and the user have a separate written agreement with warranty terms covering the material in this document that conflict with these
4. FID output will be between 5 0 and 20 0 pA when lit and lt 2 0 pA when not lit 94 Troubleshooting Troubleshooting Tasks 8 To Verify FID Ignitor Function During Ignition Sequence Troubleshooting WARNING Keep body parts at a safe distance from the FID chimney while performing this task If using hydrogen the FID flame will not be visible 1 Remove the detector top cover 2 Turn the FID flame On 3 Observe the ignitor plug though the FID chimney The small hole should glow during ignition sequence 95 8 Troubleshooting Tasks To Measure FID Leakage Current 1 Load the analytical method e Make sure flows are acceptable for ignition e Heat the detector to operating temperature or to 300 C Turn off the FID flame Verify that the FID electrometer is on Press Front Detector or Back Detector then scroll to Output Verify that the output is stable and lt 1 0 pA a FF Ww N If the output is unstable or gt 1 0 pA turn off the GC and check for proper assembly of the upper FID parts and for contamination If the contamination is confined to the detector bakeout the FID 6 Turn on the flame 96 Troubleshooting Troubleshooting Tasks 8 To Measure FID Baseline Output With the column installed load your checkout method Set the oven temperature to 35 C Press Front Detector or Back Detector then scroll to Output When the flame is lit and the GC is ready verify that the output is
5. brass knurled nut that holds the FID castle assembly in place must be tight Perform FID maintenance if these parts are corroded or oxidized T 20 Torx screws 3 Ignitor Knurled nut 16 Troubleshooting Hardware Symptoms 2 Corrosion in FID Collector and Ignitor Glow Plug Agilent recommends inspecting the collector and ignitor glow plug for corrosion while performing maintenance on the FID The FID combustion process results in condensation This condensation combined with chlorinated solvents or samples causes corrosion and sensitivity loss To avoid corrosion keep the detector temperature above 100 C Troubleshooting 17 2 Hardware Symptoms FPD Does Not Ignite e Check that the FPD temperature is high enough for ignition gt 150 C e Check FPD flow rates and that they match the type of filter installed in the FPD e Measure the actual detector flows See To Measure a Detector Flow e The column may be installed too high into the detector e Check that the FPD ignitor operates See To Verify That the FPD Flame Is Lit e Check the column and makeup flow rates e Ensure that condensation in the vent tube is not dripping back into the detector The flexible plastic vent tube must run from the detector into a container without sagging in order to properly drain water condensate Keep the open tube end out of the water in the container e Check the Lit offset value The typical L
6. do the following e Verify that you are using the correct bead for the sample being run If you are analyzing phosphorus install a black bead White beads can cause peak tailing when phosphorus is being analyzed e Verify that the correct jet is installed Use an extended jet e Replace the ceramic insulators 29 3 Chromatographic Symptoms Peak Boiling Point or Molecular Weight Discrimination Poor 30 If you have trouble with peak boiling point or molecular weight discrimination inlet discrimination do the following Check the inlet for contamination Clean and change the liner if necessary Replace all inlet consumable parts See the Maintenance manual Adjust the inlet temperature Run standards against a known method to determine expected performance For any inlet operating in split mode with any detector Check liner type Increase the inlet temperature and verify that the insulation cup is installed and contains insulation Check column cut and installation into the inlet See the topic for the SS PTV and VI For any inlet operating in splitless mode with any detector Check the inlet for leaks See Checking for Leaks Check liner type Verify that the oven starting temperature is less than the solvent boiling point Check column cut and installation into the inlet See the topic for the SS PTV and VI Check that the solvent vapor volume does not exceed the liner capacity Check
7. flow rates of concern 2 Turn off the detector 3 Turn off the detector flows 4 Connect the appropriate adapter to the detector exhaust A 1 8 in rubber adapter tube attaches directly to a uECD or TCD exhaust vent A separate adapter 19301 60660 is supplied for the FID Insert the adapter into the detector exhaust vent as far as possible You will feel resistance as the adapter O ring is forced into the detector exhaust vent Twist and push the adapter during insertion to ensure a good seal z j For the FPD remove the vent tube assembly and use a 1 4 in tube adapter between the detector exhaust and the flowmeter tubing 84 Troubleshooting Troubleshooting Tasks 8 AOM1000 zi Agilent 5 Connect the flowmeter to the flowmeter adapter to measure flow rates Measuring NPD column flow 1 Gather the following e NPD flowmeter adapter tool G1534 60640 Troubleshooting 85 8 Troubleshooting Tasks Flow measuring insert 19301 60660 e Electronic flowmeter calibrated for the gas and flow rates of concern Set the bead voltage to 0 0 V Cool the NPD to 100 C Remove the bead and store it carefully until re installation Insert the NPD flowmeter adapter tool into the NPD collector a A OO N 6 Attach the flow measuring insert to the NPD flowmeter adapter tool EE AEE Flow Tracker 1000 GC Training AW EE Aan 7 Place the flowmeter tubing over the flow measuring insert to b
8. for appropriate purge delay time Troubleshooting Chromatographic Symptoms 3 Sample Decomposition in Inlet Missing Peaks e Lower the inlet temperature e Check for air or water in the carrier gas verify gas purity and functionality of traps e Verify that the liner is appropriate for the sample being run e Perform complete inlet maintenance Replace all consumable parts and bake out the inlet e Install a deactivated liner SS PP and PTV inlets e Check for leaks at the septum liner and column fittings See Checking for Leaks e Install an Agilent Direct Connect liner e Use a pulsed pressure method for quicker sample transfer to column e Bake out the inlet See the following e To Bakeout Contaminants from the Split Splitless Inlet e To Bakeout Contaminants from the Purged Packed Inlet e To Bakeout Contaminants from the COC Inlet e To Bakeout Contaminants from the PTV Inlet To Bakeout Contaminants from the VI Inlet Troubleshooting 31 3 Chromatographic Symptoms Peak Fronting The figure below shows examples of the three types of peaks symmetric fronting and overloaded ne Symmetrical Fronting Overloaded If peak fronting or overloading occurs try the following 32 Verify that the injection volume is appropriate Ensure that the column is installed properly Verify that the appropriate injection technique is being used If using capillary splitless inj
9. stable and lt 20 pA this may take some time FP WwW N 5 Ifthe output is not stable or gt 20 pA the system or gas may be contaminated If this contamination is isolated to the detector bakeout the FID Troubleshooting 97 8 Troubleshooting Tasks To Measure NPD Leakage Current 1 Load the analytical method 2 Set the NPD Adjust Offset to Off and the Bead Voltage to 0 00 V e Leave the NPD at operating temperature e Leave flows on or off 3 Press Front Detector or Back Detector then scroll to Output 4 Verify that the output leakage current is stable and lt 1 0 pA 5 The output should slowly drop toward 0 0 pA and should stabilize in the tenths of a picoamp Current gt 2 0pA indicates a problem 98 Troubleshooting Troubleshooting Tasks 8 To Verify That the NPD Bead Is Ignited WARNING Hot exhaust Detector exhaust is hot and can cause burns To verify that the bead is ignited look through the vent hole on the detector lid to see if the bead is glowing orange The NPD output is selected by the operator as part of the adjust offset process and generally is between 5 0 and 50 0 pA Troubleshooting 99 8 Troubleshooting Tasks To Verify That the FPD Flame Is Lit To verify that the FPD flame is lit 1 Remove the rubber drip tube from the detector vent 2 Hold a mirror or shiny surface near the aluminum exhaust tube Steady condensation means that the flame is lit 100 Troubleshoo
10. terms the warranty terms in the sep arate agreement shall control Safety Notices CAUTION A CAUTION notice denotes a hazard It calls attention to an operating procedure practice or the like that if not correctly performed or adhered to could result in damage to the product or loss of important data Do not proceed beyond a CAUTION notice until the indicated conditions are fully understood and met A WARNING notice denotes a hazard It calls attention to an operating procedure practice or the like that if not correctly performed or adhered to could result in personal injury or death Do not proceed beyond a WARNING notice until the indicated conditions are fully understood and met Contents 1 Concepts and General Tasks Concepts 8 How to troubleshoot using this manual 8 The Status key 8 Configurable Items to Always Keep Current 9 Column configuration 9 Automatic Liquid Sampler configuration 9 Gas configuration 9 Information to Obtain Before Calling Agilent for Service 10 2 Hardware Symptoms Plunger Errors 12 Vial Mishandled by ALS 13 Syringe Needle Bends During Injection into Inlet 14 FID Does Not Ignite 15 FID Ignitor Does Not Glow During Ignition Sequence 16 Corrosion in FID Collector and Ignitor Glow Plug 17 FPD Does Not Ignite 18 NPD Adjust Offset Process Fails 19 3 Chromatographic Symptoms Retention Times Not Repeatable 22 Peak Areas Not Repeatable 23 Contamination or Carryover 24 Isolate
11. the source 24 Check possible causes all inlet and detector combinations Larger Peaks Than Expected 25 Peaks Not Displayed No Peaks 26 Table 1 Detector troubleshooting 26 Baseline Rise During Oven Temperature Program 27 Troubleshooting 24 Poor Peak Resolution 28 Peak Tailing 29 NPD 29 Peak Boiling Point or Molecular Weight Discrimination Poor 30 For any inlet operating in split mode with any detector 30 For any inlet operating in splitless mode with any detector 30 Sample Decomposition in Inlet Missing Peaks 31 Peak Fronting 32 Noisy Detector Including Wander Drift and Baseline Spikes 33 Noisy baseline 33 Baseline wander and drift 34 Baseline spiking 34 Figure 1 Cyclic spiking 35 Figure 2 Random spiking 35 Check for the correct jet Low Peak Area or Height 36 FID Flame Goes Out During a Run and Attempts to Reignite 38 FID Baseline Output Above 20 pA 39 FPD Flame Goes Out During a Run and Attempts to Reignite 40 FPD Output Too High or Too Low 41 FPD Low Peak Areas 42 FPD Large Peak Width at Half Height 43 FPD Baseline Output High gt 20pA 44 NPD Solvent Quenching 45 NPD Response Low 46 NPD Baseline Output gt 8 million 47 NPD Adjust Offset Process Not Functioning Properly 48 NPD Low Selectivity 49 Negative Peaks Seen with TCD 50 TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks Ringing Baseline 51 TCD Peaks Have Negative Dip on Tail 52 4 GC Not Ready Symptoms GC Never Becomes Ready 54 Fl
12. three T 20 Torx screws that hold the collector assembly in place must be tight e The brass knurled nut that holds the FID castle assembly in place must be tight Perform FID maintenance if these parts are corroded or oxidized T 20 Torx screws 3 Ignitor Knurled nut 66 Troubleshooting GC Not Ready Symptoms NPD Adjust Offset Process Fails Troubleshooting Inspect the jet to see if it is clogged Measure the actual detector flows See To Measure a Detector Flow Check the condition of the bead Replace if necessary Verify that the flow settings are correct Thoroughly leak check the whole system especially the detector column fitting See Checking for Leaks Set the equilibration time to 0 0 67 4 GC Not Ready Symptoms FPD Does Not Ignite e Check that the FPD temperature is high enough for ignition gt 150 C e Check FPD flow rates and that they match the type of filter installed in the FPD e Measure the actual detector flows See To Measure a Detector Flow e The column may be installed too high into the detector e Check that the FPD ignitor operates See To Verify That the FPD Flame Is Lit e Check the column and makeup flow rates e Ensure that condensation in the vent tube is not dripping back into the detector The flexible plastic vent tube must run from the detector into a container without sagging in order to properly drain water condensate Keep the ope
13. 27 3 Chromatographic Symptoms Poor Peak Resolution e Set column flow to optimum linear velocity e Install and use deactivated consumable parts in the inlet for example a liner e Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed e Check column installation at both ends e Select a higher resolution column 28 Troubleshooting Peak Tailing Troubleshooting NPD Chromatographic Symptoms 3 The figure below shows an example of tailing peaks When troubleshooting tailing peaks consider e Which peaks are tailing e Are the tailing peaks active compounds all compounds or are there trends such as early eluters or late eluters e Check the column for severe contamination e Consider the column stationary phase active column e Verify that the column was cut and installed properly e Consider the type of adapter liner and inlet seal being used One or all of these may be contaminated or active e Check adapters if installed and liner for solid particles e For capillary splitless injection consider compatibility between the solvent and column e Verify that the injection technique is adequate e Verify the inlet temperature e Check for dead volume in the system Check for correct column installation at both ends e Inspect any transfer lines for cold spots For NPD
14. Off For example if the front inlet ran out of carrier gas press Front Inlet scroll to the pressure or flow parameter then press On The GC cannot detect leaks in the detector gas streams For this reason it is vital that the column fittings of the FID NPD and any other detectors that use hydrogen always be connected to a column or have a cap or plug installed and that hydrogen streams be configured so that the GC is aware of them Troubleshooting 71 5 Shutdown Symptoms Thermal Shutdowns 72 A thermal fault means that the oven or another heated zone is not within its allowable temperature range lower than minimum temperature or higher than maximum temperature To recover from this state 1 Fix the cause of the shutdown e Check for missing insulation 2 Most thermal shutdowns can be cleared by shutting off the thermal zone Troubleshooting Agilent 6890N Gas Chromatograph Troubleshooting 6 Nonfunctional GC Symptoms GC Does Not TurnOn 74 PC Cannot Communicate with GC 75 Ee Agilent Technologies 73 6 Nonfunctional GC Symptoms GC Does Not Turn On If the GC does not turn on e Check the power cord e Check the building s power e Ifthe problem is at the GC turn off the GC power Wait 30 seconds then turn the on the GC power 74 Troubleshooting Nonfunctional GC Symptoms 6 PC Cannot Communicate with GC Troubleshooting e Runa ping test The MS DOS ping command verifie
15. as type The configured gas type must match the actual gas plumbed to the GC e Check for leaks in the gas delivery plumbing and the GC See Checking for Leaks Troubleshooting 55 4 GC Not Ready Symptoms Oven Temperature Never Cools Down Cools Very Slowly If the oven does not cool down or cools down very slowly WARNING The exhaust coming from the back of the GC is very hot Keep hands and face away from the exhaust vent e Check oven flapper operation 1 Decrease oven temperature by at least 20 degrees 2 Verify that the oven flaps in the back of the GC are open Listen to verify that the fan is operating The figure below illustrates the location of the two oven flaps If the flaps are not operating smoothly contact Agilent for service fers If using cryo cooling e Check for sufficient cryo coolant e Check if operating limits are exceeded 56 Troubleshooting Oven Never Heats Up Troubleshooting GC Not Ready Symptoms 4 e Press Status to check for errors to report to Agilent The exhaust coming from the back of the GC is very hot Keep hands and face away from the exhaust vent e Power cycle the GC e Check oven flapper operation 1 Increase oven temperature by at least 20 degrees 2 Verify that the oven flaps in the back of the GC are closed The figure below illustrates the location of the two oven flaps If the flap is stuck open
16. clean baseline do the following e Consider recent changes made to the system e Bakeout the inlet See the following e To Bakeout Contaminants from the Split Splitless Inlet e To Bakeout Contaminants from the Purged Packed Inlet To Bakeout Contaminants from the COC Inlet 33 3 Chromatographic Symptoms e To Bakeout Contaminants from the PTV Inlet e To Bakeout Contaminants from the VI Inlet e Verify the purity of carrier and detector gases e Verify proper reassembly after recent maintenance e Inspect the detector for contamination If noise increases gradually to an unacceptable level check the following possible causes e Inspect the detector for contamination e Inspect the column and inlet for contamination e Inspect the FID or NPD jet for contamination e Verify that the FPD photomultiplier tube PMT is properly installed If it is not light leaks and ultimately noise will result Other factors that can contribute to noise e Column installed too high into detector e Oven temperature exceeds column maximum recommended temperatures Baseline wander and drift e Baseline wander or drift can occur when a flow or temperature setting is changed If the system has not stabilized at the new conditions before it starts a run some baseline changes are to be expected If experiencing baseline wander check for leaks especially at the septum and at the column See Checking for Leaks Baseline drift is most oft
17. ctronic flowmeter calibrated for the gas and flow rates of concern Set the bead voltage to 0 0 V Cool the NPD to 100 C Remove the bead and store it carefully until re installation Insert the NPD flowmeter adapter tool into the NPD collector a A OO N 6 Attach the flow measuring insert to the NPD flowmeter adapter tool EE AEE Flow Tracker 1000 GC Training AW EE Aan 7 Place the flowmeter tubing over the flow measuring insert to begin measuring flows Troubleshooting 91 8 Troubleshooting Tasks To Perform the GC Self Test 1 Turn the GC off 2 Wait 1 min then turn the GC back on If the main GC status screen appears the GC has passed the self test Agilent 6892N GC Vesion N 5 5 Power on successful 92 Troubleshooting To Adjust the FID Lit Offset Troubleshooting Troubleshooting Tasks 8 To adjust the FID Lit offset 1 2 Press Config Scroll to Front detector or Back detector wherever the detector is installed and press Enter Scroll to Lit offset With the Lit offset line highlighted enter the new parameter for the detector and press Enter Lit offset should be lt 2 0 pA or lower than the normal FID output when lit 93 8 Troubleshooting Tasks To Verify That the FID Flame Is Lit To verify that the FID flame is lit hold a mirror or other reflective surface over the collector exhaust Steady condensation indicates that the flame is lit Typically the
18. dth at Half Height 43 FPD Baseline Output High gt 20 pA 44 NPD Solvent Quenching 45 NPD Response Low 46 NPD Baseline Output gt 8 million 47 NPD Adjust Offset Process Not Functioning Properly 48 NPD Low Selectivity 49 Negative Peaks Seen with TCD 50 TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks Ringing Baseline 51 TCD Peaks Have Negative Dip on Tail 52 hte Agilent Technologies 3 Chromatographic Symptoms Retention Times Not Repeatable 22 Replace the septum Check for leaks in the inlet liner as applicable and column connection See Checking for Leaks Check for sufficient carrier gas supply pressure The pressure delivered to the GC must be at least 40 kPa 10 psi greater than the maximum inlet pressure required at final oven temperature Run replicates of known standards to verify the problem Check for leaks at the inlet See Leak Check Tips Verify that you are using the correct liner type for the sample being injected Consider if this is this first run Has the GC stabilized If using an FID or NPD and retention times increase drift check the jet for contamination Troubleshooting Chromatographic Symptoms 3 Peak Areas Not Repeatable e Check the ALS syringe operation See the Troubleshooting section of the 7683B Automatic Liquid Sampler Installation Operation and Maintenance manual e Replace the syringe e Check for leaks in the inlet liner
19. e NPD Leakage Current 98 To Verify That the NPD Bead Is Ignited 99 To Verify That the FPD Flame Is Lit 100 To Adjust the FPD Lit Offset 101 95 Troubleshooting e Agilent 6890N Gas Chromatograph e Troubleshooting e e fa Pa e ee 1 7 e Concepts and General Tasks e o j e Concepts 8 s Configurable Items to Always Keep Current 9 Information to Obtain Before Calling Agilent for Service 10 egip Agilent Technologies 1 Concepts and General Tasks Concepts This manual provides lists of symptoms and corresponding tasks to perform should you experience errors associated with GC hardware or chromatographic output GC Not Ready messages and other common issues Each section describes a problem and provides a bulleted list of possible causes for you to troubleshoot These lists are not intended for use in the development of new methods Proceed with troubleshooting under the assumption that method s are working properly This manual also includes common troubleshooting tasks as well as information needed prior to calling Agilent for service How to troubleshoot using this manual The Status key Use the following steps as a general approach to troubleshooting 1 Observe the symptoms of the problem 2 Look up the symptoms in this manual using the Table of Contents or the Search tool Review the list of possible causes of the symptom 3 Check each possible cause or perform a test that narrows the li
20. e following e Check the GC system for leaks especially at the detector column fitting See Checking for Leaks e Verify the detector temperature is set gt 200 C e Ensure that condensation in the vent tube is not dripping back into the detector The flexible plastic vent tube must run from the detector into a container without sagging in order to properly drain water condensate Keep the open tube end out of the water in the container If the FPD flame goes out and then reignites do the following e Verify that the Lit offset setting is lower than the normal baseline e Check for leaks See Checking for Leaks e Check the flow settings then measure the actual detector flows See To Measure a Detector Flow Troubleshooting Chromatographic Symptoms 3 FPD Output Too High or Too Low e Verify that the correct filter is being used Do not use a phosphorus filter with sulfur optimized flows or a sulfur filter with phosphorus optimized flows e Check the position of the column as installed in the detector e Check the gas purity Troubleshooting 41 3 Chromatographic Symptoms FPD Low Peak Areas 42 Check the flow settings then measure the actual detector flows See To Measure a Detector Flow Perform complete inlet maintenance Replace all consumable parts and bake out the inlet Perform column maintenance Bake out contaminants remove the contaminated length of colum
21. ection consider the compound solubility in the injection solvent e Change the solvent e Use a retention gap Check purity of sample solvent Troubleshooting Chromatographic Symptoms 3 Noisy Detector Including Wander Drift and Baseline Spikes Total noise Noise should be measured under normal operating conditions with a column connected and carrier gas on Noise typically has a high frequency component electronic in origin and lower frequency components that are referred to as wander and drift Wander is random in direction but at a lower frequency than the short term electronic noise Long term noise drift is a monotonic change in signal over a period that is long compared to the wander and electronic noise see below Terms like short and long are relative to the width of the chromatographic peaks Long term noise drift Eee Wander PRP DOO DA pr Short term noise Noisy baseline Troubleshooting A noisy baseline or high detector output can indicate leaks contamination or electrical problems Some noise is inevitable with any detector although high attenuations can mask it Since noise limits useful detector sensitivity it should be minimized e For all detectors check for leaks at the column fittings See Checking for Leaks e For the FID see To Measure NPD Leakage Current e For the TCD verify data collection at lt 5 Hz If noise appears suddenly on a previously
22. eeds Pressure Setpoint or Flow 61 The Inlet Pressure or Flow Fluctuates 62 Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet 63 The Measured Column Flow Does Not Equal the Displayed Flow 64 FID Does Not Ignite 65 FID Ignitor Does Not Glow During Injection Sequence 66 NPD Adjust Offset Process Fails 67 FPD Does Not Ignite 68 This section includes faults and symptoms that will occur when the GC is on but cannot perform analyses This is indicated by a Not Ready warning by fault messages or by other symptoms 33 Agilent Technologies 53 4 GC Not Ready Symptoms GC Never Becomes Ready 54 Normally the GC becomes ready after flows and temperatures reach setpoint If the GC does not become ready after a long period of time e Press Status or a component key for example Front inlet to see which setpoints or conditions are not ready e Check for a sampler problem e Check for a data system problem e If performing manual injections in splitless or gas saver mode you may need to press Prep Run to prepare the inlet for the injection Do this for example e To toggle the inlet purge valve before a splitless injection e To prepare for a pulsed injection e To turn off gas saver Troubleshooting GC Not Ready Symptoms 4 Flow Never Becomes Ready If the gas flow never becomes ready check for the following e Check the supply gas for sufficient delivery pressure e Check the configured g
23. egin measuring flows 86 Troubleshooting Troubleshooting Tasks 8 To Measure a Split Vent or Septum Purge Flow WARNING Hydrogen H2 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition Septum purge and split vent flows exit through the pneumatic module at the top rear of the GC See the figure below Front inlet split vent P Back inlet split vent Front inlet septum purge z vent i Back inlet septum purge vent To measure split vent or septum purge flows attach the flowmeter to the appropriate tube Remove the GC pneumatics cover to access the back inlet exhausts e The vents use a 1 8 in Swagelok threaded fitting Create and use a 1 8 in tube adapter as shown below to convert the 1 8 in threaded fitting into a 1 8 in tube This prevents the rubber flowmeter tubing from leaking around the threads which will result in leakage and thus an incorrect flow reading Troubleshooting 87 8 Troubleshooting Tasks Soe pihia migi Yel 88 Troubleshooting Troubleshooting Tasks 8 To Measure a Detector Flow Troubleshooting Measuring FID TCD uECD and FPD flows Hydrogen H3 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowm
24. en seen during temperature programming To correct baseline drift do the following Verify that column compensation is used and the profile is current To compensate for bleed e Verify that the column is conditioned e Check column bleed while at operating temperature e Check the signal mode assigned to the column in the data system Baseline spiking There are two types of spiking on the baseline output cyclic and random 34 Troubleshooting Troubleshooting Chromatographic Symptoms 3 Figure 1 Cyclic spiking Cyclic spiking can be caused by the following e An electric motor e Building heating cooling system e Other electronic interferences in the lab Figure 2 Random spiking e Spikes are isolated baseline disturbances usually appearing as sudden and large upscale movements If accompanied by noise resolve the noise problem first since spiking may disappear at the same time Check for a contaminated detector e For a packed column check that the packed column exit is properly sealed with glass wool e Check packed column installation 35 3 Chromatographic Symptoms Check for the correct jet Low Peak Area or Height 36 If using an inlet in split mode check the split ratio Check for leaks See Checking for Leaks Check the inlet for contamination See Contamination or Carryover Check each column and verify that it was cut and installed properly at each end Verify that
25. eters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition CAUTION 1 Gather the following e Appropriate flowmeter adapter tube can be found in the GC ship kit e Electronic flowmeter calibrated for the gas and flow rates of concern To avoid damaging the column cool the oven before turning off the column flow 2 Set the oven temperature to ambient 35 C 3 Turn off the column flow and pressure 4 Turn off where applicable the FID flame FPD flame and TCD filament 5 Cool the detector 6 Connect the appropriate adapter to the detector exhaust A rubber adapter tube attaches directly to a uECD or TCD exhaust vent A separate adapter is supplied for the FID Insert the adapter into the detector exhaust vent as far as possible You will feel resistance as the adapter O ring is forced into the detector exhaust vent Twist and push the adapter during insertion to ensure a good seal 55 ae For FPD remove the vent tube assembly and use a 1 4 inch tube adapter between the detector exhaust and the flowmeter tubing 8 Troubleshooting Tasks AOM1000 3e Agilent 7 Connect the flowmeter to the flowmeter adapter and measure flows Measuring NPD flows 1 Gather the following e NPD flowmeter adapter tool G1534 60640 90 Troubleshooting Troubleshooting Tasks 8 Flow measuring insert 19301 60660 e Ele
26. f the front inlet ran out of carrier gas press Front Inlet scroll to the pressure or flow parameter then press On 70 Troubleshooting Hydrogen Shutdown Shutdown Symptoms 5 Hydrogen gas may be used as a carrier or as fuel for some detectors When mixed with air hydrogen can form explosive mixtures The GC monitors inlet and auxiliary gas streams If a stream shuts down because it is unable to reach its flow or pressure setpoint and if that stream is configured to use hydrogen the GC assumes that a leak has occurred and shuts down components to create a safe state The GC e Closes the carrier supply valve to the inlet and closes and turns off both pressure and flow controls When viewed these parameters will flash Off e Opens the split vent valves in the split splitless and PTV inlets e Turns off the oven heater and fan and opens the oven flaps e Turns off all heaters including any devices connected to the auxiliary heater controls such as valve box heaters and transfer line heaters When viewed these parameters will flash Off e Sounds an alarm To recover from this state 1 Fix the cause of the shutdown e Replace the inlet septum e Replace the inlet O ring e Check for broken column e Check the supply pressure e Check the system for leaks See Checking for Leaks 2 Press the key for the device that initiated the shutdown Scroll to the pneumatic parameter that is flashing Off then press On or
27. hecking for leaks consider the system in two parts external leak points and GC leak points e External leak points include the gas cylinder or gas purifier regulator and its fittings supply shutoff valves and connections to the GC supply fittings e GC leak points include inlets detectors column connections valve connections and connections between flow modules and inlets detectors WARNING Hydrogen H2 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition WARNING Hazardous sample gases may be present 1 Gather the following e Electronic leak detector capable of detecting the gas type e 7 16 in 9 16 in and 1 4 in wrenches for tightening Swagelok and column fittings 2 Check any potential leak points associated with any maintenance recently performed 3 Check GC fittings and connections that undergo thermal cycling since thermal cycling tends to loosen some fitting types Use the electronic leak detector to determine if a fitting is leaking e Start by checking any newly made connections first e Remember to check connections in the gas supply lines after changing traps or supply cylinders 78 Troubleshooting Checking forLeaks 7 To Check for External Leaks Check for leaks at these connecti
28. it offset value is 2 0 e Thoroughly leak check the whole system See Checking for Leaks 18 Troubleshooting Hardware Symptoms NPD Adjust Offset Process Fails Troubleshooting Inspect the jet to see if it is clogged Measure the actual detector flows See To Measure a Detector Flow Check the condition of the bead Replace if necessary Verify that the flow settings are correct Thoroughly leak check the whole system especially the detector column fitting See Checking for Leaks Set the equilibration time to 0 0 2 Hardware Symptoms 20 Troubleshooting e Agilent 6890N Gas Chromatograph e Troubleshooting e e a Pa o e 0 ee 3 7 e Chromatographic Symptoms e o j e Retention Times Not Repeatable 22 Peak Areas Not Repeatable 23 Contamination or Carryover 24 Larger Peaks Than Expected 25 Peaks Not Displayed No Peaks 26 Baseline Rise During Oven Temperature Program 27 Poor Peak Resolution 28 Peak Tailing 29 Peak Boiling Point or Molecular Weight Discrimination Poor 30 Sample Decomposition in Inlet Missing Peaks 31 Peak Fronting 32 Noisy Detector Including Wander Drift and Baseline Spikes 33 Check for the correct jet Low Peak Area or Height 36 FID Flame Goes Out During a Run and Attempts to Reignite 38 FID Baseline Output Above 20 pA 39 FPD Flame Goes Out During a Run and Attempts to Reignite 40 FPD Output Too High or Too Low 41 FPD Low Peak Areas 42 FPD Large Peak Wi
29. n tube end out of the water in the container e Check the Lit offset value The typical Lit offset value is 2 0 e Thoroughly leak check the whole system See Checking for Leaks 68 Troubleshooting e Agilent 6890N Gas Chromatograph e Troubleshooting e e sa Pa oo o 5 7 e Shutdown Symptoms m J J j e S Column Shutdown 70 s Hydrogen Shutdown 71 Thermal Shutdowns 72 Agg Agilent Technologies 5 Shutdown Symptoms Column Shutdown If a carrier gas which can include an auxiliary flow module or pneumatics control module shuts down the following happens e The oven turns off to avoid column damage e The oven flaps in the back of the oven open halfway e The oven temperature setpoint flashes Off e All flows for the column turn off When viewed their parameters flash Off For example the septum purge and column flows for a split splitless inlet would turn off e All other heaters turn off When viewed their temperature parameters flash Off e Attempts to turn on a shut down zone fail with an error message e The instrument beeps To recover from this state 1 Fix the cause of the shutdown e Check for a broken column e Replace the inlet septum e Replace the inlet O ring e Check the supply pressure e Check for leaks 2 Press the key for the device that initiated the shutdown Scroll to the pneumatic parameter that is flashing Off then press On or Off For example i
30. n near the inlet and reverse and bake out the column as needed Verify that the column is installed properly Consider the filter type sulfur or phosphorus Check the system for leaks See Checking for Leaks Verify that the method settings are appropriate Check the flow rates Check the makeup gas type Troubleshooting Chromatographic Symptoms 3 FPD Large Peak Width at Half Height If the FPD produces peaks that are abnormally wide at half the peak height do the following Check the actual injection volume reduce if necessary e Verify that the liner is not reacting with the sample Troubleshooting 43 3 Chromatographic Symptoms FPD Baseline Output High gt 20 pA e Check the supply gas purity e Check all trap indicators and dates e Check the detector for contamination e Check for light leaks at the photomultiplier tube PMT tighten the PMT if it is loose e Perform complete inlet maintenance Replace all consumable parts and bake out the inlet e Perform column maintenance Bake out contaminants as needed 44 Troubleshooting NPD Solvent Quenching Troubleshooting Chromatographic Symptoms If the baseline does not recover after a solvent peak try the following e Turn hydrogren off on around the solvent peak e Use nitrogen as the makeup gas e Set the total column flow and makeup gas to less than 10 mL min e Increase the air flow by 10 mL min e Increase the detector
31. ng Ignition Sequence Verify that the Lit Offset is lt 2 0 pA Check for a plugged or partially plugged jet Check the FID flow rates The hydrogen air ratio greatly impacts ignition Nonoptimal flow settings can prevent flame ignition See To Measure a Detector Flow There could be a large leak in the system if the flame still will not light Large leaks result in measured flow rates being different from actual flow rates causing nonideal ignition conditions Thoroughly leak check the whole system especially the column fitting at the FID Check the column flow rate Check for leaks at the FID column fitting Ensure that the FID temperature is high enough for ignition gt 150 C 65 4 GC Not Ready Symptoms FID Ignitor Does Not Glow During Injection Sequence WARNING Keep body parts at a safe distance from the FID chimney while performing this task If using hydrogen the FID flame will not be visible 1 Remove the detector top cover 2 Turn the FID flame On 3 Observe the ignitor plug though the FID chimney The small hole should glow during ignition sequence If the test fails check for the following possible causes e The ignitor may be bad replace the ignitor e Detector temperature is set to lt 150 C Agilent recommends operating the FID at gt 300 C e The ignitor is not making a good connection to the ground e The ignitor must be tightly screwed into the FID castle assembly e The
32. o inspect the plat and connection for a broken column tip 82 Troubleshooting Agilent 6890N Gas Chromatograph Troubleshooting 8 Troubleshooting Tasks To Measure a Column Flow 84 To Measure a Split Vent or Septum Purge Flow 87 To Measure a Detector Flow 89 To Perform the GC Self Test 92 To Adjust the FID Lit Offset 93 To Verify That the FID Flame Is Lit 94 To Verify FID Ignitor Function During Ignition Sequence 95 To Measure FID Leakage Current 96 To Measure FID Baseline Output 97 To Measure NPD Leakage Current 98 To Verify That the NPD Bead Is Ignited 99 To Verify That the FPD Flame Is Lit 100 To Adjust the FPD Lit Offset 101 Ee Agilent Technologies 83 8 Troubleshooting Tasks To Measure a Column Flow Measuring FID TCD uECD and FPD column flow The following procedure can be used to measure column flow with an FID TCD uECD and FPD WARNING Hydrogen H3 is flammable and is an explosion hazard when mixed with air in an enclosed space for example a flow meter Purge flowmeters with inert gas as needed Always measure gases individually Always turn off detectors to prevent flame bead autoignition WARNING Be careful The detector may be hot enough to cause burns If the detector is hot wear heat resistant gloves to protect your hands 1 Gather the following e Appropriate flowmeter adapter tube can be found in the GC ship kit e Electronic flowmeter calibrated for the gas and
33. om a large solvent peak 3 4 5 min After a flameout the GC will try to ignite the flame three times If the FID flame goes out during a run do the following See if an aromatic peak or water extinguished the flame Check for a plugged jet Verify that the gas flow settings are correct Verify that Lit offset is set appropriately If the FID flame attempts to reignite but is already lit do the following Verify that the FID Lit offset setting is appropriate for the run typically lt 2 0 pA Check to see if an aromatic peak or water extinguished the flame Check for a partially plugged jet Measure actual hydrogen air and makeup flows at the detector See To Measure a Detector Flow Check for leaks at the detector column fitting See Checking for Leaks Troubleshooting Chromatographic Symptoms 3 FID Baseline Output Above 20 pA e Verify the purity of the carrier and detector gas supply e Inspect the column for column bleed e Check the gas supply trap indicators dates and ensure that the traps are not expended e Verify that the detector was reassembled properly after recent maintenance e Inspect the detector for contamination e Check that the FID leakage current is lt 2 0 pA See To Measure FID Leakage Current Troubleshooting 39 3 Chromatographic Symptoms FPD Flame Goes Out During a Run and Attempts to Reignite 40 If the flame goes out during a run do th
34. ons Troubleshooting e Gas supply bulkhead fittings e Gas cylinder fitting e Regulator fittings e Traps e Shut off valves e T fittings Perform a pressure drop test 1 Turn off the GC 2 Set the regulator pressure to 415 kPa 60 psi 79 7 Checking for Leaks 3 Fully turn the regulator knob counterclockwise to shut the valve 4 Wait 5 min If there is a measurable drop in pressure there is a leak in the external connections No drop in pressure indicates that the external connections are not leaking 80 Troubleshooting Checking forLeaks 7 To Check for GC Leaks Check for leaks at these connections e Inlet septum septum head liner split vent trap split vent trap line and purge vent fittings e Column connections to inlets detectors valves splitters and unions e Fittings from the flow modules to the inlets detectors and valves e Column adapters e Agilent capillary flow fittings Troubleshooting 81 7 Checking for Leaks Leaks in Capillary Flow Microfluidic Fittings For capillary flow fittings a leak usually indicates that the fitting has been overtightened Unless the fitting is obviously loose do not tighten it further Instead remove the connection trim the column end and install it again See To Attach a Capillary Column Using SilTite Metal Fittings Als
35. or if the flaps are closed and the oven still does not heat contact Agilent rozo 57 4 GC Not Ready Symptoms Temperature Never Becomes Ready To be considered ready a temperature must be at setpoint 1 C for 30 s If a temperature never becomes ready do the following e Check for a missing insulation cup on an inlet or detector e Check for a very large temperature difference between the oven and inlet or detector e Check for missing insulation around the inlet or detector e If using a cool on column with CryoBlast or a PTV inlet e Check cryo coolant level e Check if operating limits have been exceeded 58 Troubleshooting GC Not Ready Symptoms 4 Cannot Set a Flow or Pressure If you cannot set a flow or pressure using the split splitless PTV VI or cool on column inlets do the following e Check the column mode e Check that a capillary column is configured to the correct inlet e Check the configured column dimensions e Check that the flow is turned on If you cannot set a flow or pressure using the purged packed inlet do the following e Check the column mode The packed inlet uses flow control for undefined columns e Check that the flow is turned on Troubleshooting 59 4 GC Not Ready Symptoms A Gas Does Not Reach Setpoint Pressure or Flow If an inlet does not reach its pressure setpoint it will shut down in an amount of
36. ow Never Becomes Ready 55 Troubleshooting Oven Temperature Never Cools Down Cools Very Slowly 56 Oven Never Heats Up 57 Temperature Never Becomes Ready 58 Cannot Seta Flow or Pressure 59 A Gas Does Not Reach Setpoint Pressure or Flow 60 A Gas Exceeds Pressure Setpoint or Flow 61 The Inlet Pressure or Flow Fluctuates 62 Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet 63 The Measured Column Flow Does Not Equal the Displayed Flow 64 FID Does Not Ignite 65 FID Ignitor Does Not Glow During Injection Sequence 66 NPD Adjust Offset Process Fails 67 FPD Does Not Ignite 68 5 Shutdown Symptoms Column Shutdown 70 Hydrogen Shutdown 71 Thermal Shutdowns 72 6 Nonfunctional GC Symptoms GC Does Not Turn On 74 PC Cannot Communicate with GC 75 7 Checking for Leaks Leak Check Tips 78 To Check for External Leaks 79 To Check for GC Leaks 81 Leaks in Capillary Flow Microfluidic Fittings 82 8 Troubleshooting Tasks To Measure a Column Flow 84 Measuring FID TCD uECD and FPD column flow 84 Measuring NPD column flow 85 To Measure a Split Vent or Septum Purge Flow 87 To Measure a Detector Flow 89 Measuring FID TCD uECD and FPD flows 89 Troubleshooting Measuring NPD flows 90 To Perform the GC Self Test 92 To Adjust the FID Lit Offset 93 To Verify That the FID Flame Is Lit 94 To Verify FID Ignitor Function During Ignition Sequence To Measure FID Leakage Current 96 To Measure FID Baseline Output 97 To Measur
37. r a plugged or partially plugged jet Check the FID flow rates The hydrogen air ratio greatly impacts ignition Nonoptimal flow settings can prevent flame ignition See To Measure a Detector Flow There could be a large leak in the system if the flame still will not light Large leaks result in measured flow rates being different from actual flow rates causing nonideal ignition conditions Thoroughly leak check the whole system especially the column fitting at the FID Check the column flow rate Check for leaks at the FID column fitting Ensure that the FID temperature is high enough for ignition gt 150 C 2 Hardware Symptoms FID Ignitor Does Not Glow During Ignition Sequence WARNING Keep body parts at a safe distance from the FID chimney while performing this task If using hydrogen the FID flame will not be visible 1 Remove the detector top cover 2 Turn the FID flame On 3 Observe the ignitor plug though the FID chimney The small hole should glow during ignition sequence If the test fails check for the following possible causes e The ignitor may be bad replace the ignitor e Detector temperature is set to lt 150 C Agilent recommends operating the FID at gt 300 C e The ignitor is not making a good connection to the ground e The ignitor must be tightly screwed into the FID castle assembly e The three T 20 Torx screws that hold the collector assembly in place must be tight e The
38. ressure Verify that the supply pressure regulator is functioning properly Check for leaks See Checking for Leaks Check for large restrictions in the inlet liner or split vent trap Verify that the correct liner is installed Check for a restriction in headspace purge and trap and any other external sampling devices Troubleshooting GC Not Ready Symptoms Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet Troubleshooting If the GC cannot maintain a pressure as low as the setpoint check for the following Consider using a liner designed for split analysis Check for a plugged liner Check for contamination in the split vent line Contact Agilent service to replace if necessary Replace gold seal 63 4 GC Not Ready Symptoms The Measured Column Flow Does Not Equal the Displayed Flow If the actual column flow does not match the calculated flow displayed on the GC do the following e Verify that the measured flows are corrected to 25 C and 1 atmosphere e Verify that the correct column dimensions are configured accurately including the actual trimmed column length e The split vent line or trap may be partly plugged creating an actual inlet pressure higher than the setpoint pressure 64 Troubleshooting FID Does Not Ignite Troubleshooting GC Not Ready Symptoms 4 Check that the FID ignitor glows during ignition sequence See To Verify FID Ignitor Function Duri
39. rmation When you find a mishandled sample vial do the following Check for folds or wrinkles in the crimp cap especially near the neck of the sample vial Use Agilent recommended sample vials Check sample labels if applicable e Check that they are the correct size e Verify that the labels do not interfere with the gripper Check that the tray quadrants are clean and snapped into the tray base 2 Hardware Symptoms Syringe Needle Bends During Injection into Inlet 14 When troubleshooting the injector keep your hands away from the syringe needle The needle is sharp and may contain hazardous chemicals Refer to the 7683B Automatic Liquid Sampler Installation Operation and Maintenance manual for additional information Check that the GC septum nut is not too tight Check that the syringe is installed correctly into the syringe carriage Check that the needle support and guide are clean Remove any residue or septum deposits If using the cool on column inlet check that the correct insert for the syringe is installed Check that you are using the proper syringe The combined length of the syringe barrel and needle should be approximately 126 5 mm Troubleshooting FID Does Not Ignite Troubleshooting Hardware Symptoms 2 Check that the FID ignitor glows during ignition sequence See To Verify FID Ignitor Function During Ignition Sequence Verify that the Lit Offset is lt 2 0 pA Check fo
40. s communications across a TCP IP connection To use it open the command prompt window Type ping followed by an IP address For example if the IP address is 10 1 1 101 enter ping 10 1 1 101 If LAN communications are working properly you will see a successful reply For example B Command Prompt Microsoft Windows XP Version 5 1 2606 lt C gt Copyright 1985 2661 Microsoft Corp C gt ping 146 1 1 161 Pinging 18 1 1 101 with 32 bytes of data bytes 32 time lt ims TTL 128 bytes 32 time lt ims TTL 128 bytes 32 time lt ims TTL 128 bytes 32 time lt ims TTL 128 ics for 10 1 1 101 Sent 4 Received 4 Lost loss Approximate round trip times in milli seconds Minimum ms Maximum ms Average Gms GSN If the ping test is successful check the software configuration If the ping test is unsuccessful do the following e Check the LAN cabling e Verify the IP address subnet mask and gateway addresses e Check that a crossover cable for single GC to computer direct connection is installed 75 6 Nonfunctional GC Symptoms 76 Troubleshooting e Agilent 6890N Gas Chromatograph e Troubleshooting e e ee Pa o e c amp o 7 909 Checking for Leaks m J J j e Leak Check Tips 78 To Check for External Leaks 79 To Check for GC Leaks 81 Leaks in Capillary Flow Microfluidic Fittings 82 Ee Agilent Technologies 7 Checking for Leaks Leak Check Tips When c
41. st of possible causes until the symptom is resolved Be sure to also use the Status and Info keys on the GC keypad while using this troubleshooting information These keys will display additional useful information related to the status of the GC and its components Troubleshooting Concepts and General Tasks 1 Configurable Items to Always Keep Current Troubleshooting Certain configurable items in the GC must always be kept current Failure to do so will lead to reduced sensitivity chromatographic errors and possible safety concerns Column configuration Reconfigure the GC every time a column is trimmed or changed Also verify that the data system reflects the correct column type length id and film thickness The GC relies on this information to calculate flows Not updating the GC after altering a column causes incorrect flows changed or incorrect split ratios retention time changes and peak shifts Automatic Liquid Sampler configuration Keep the Automatic Liquid Sampler ALS configuration up to date to ensure proper operation ALS items to keep current include injector position installed syringe size and solvent and waste bottle usage Gas configuration Always configure the GC appropriately when working with hydrogen Hydrogen leaks quickly and poses a safety concern if too much of it is released into the air or into the GC oven Reconfigure the GC every time the gas type is changed If the GC is config
42. temperature to 325 C e Implement an Agilent Dean s switch solvent vent solution 45 3 Chromatographic Symptoms NPD Response Low 46 Perform complete inlet maintenance Replace all consumable parts and bake out the inlet Perform column maintenance Bake out contaminants as needed Verify correct column installation A large concentration of solvent has extinguished the hydrogen air plasma Increase the bead voltage Measure the actual gas flow at the detector See To Measure a Detector Flow Check for a partially plugged jet Verify that the bead is activated Look through the vent hole on the detector lid to see if the bead is glowing orange Replace the insulators collector Troubleshooting Chromatographic Symptoms 3 NPD Baseline Output gt 8 million e The collector is shorted to the detector housing Disassemble the collector and insulators and reinstall Troubleshooting 47 3 Chromatographic Symptoms NPD Adjust Offset Process Not Functioning Properly 48 e Inspect the jet to see if it is clogged e Measure the actual detector flows See To Measure a Detector Flow e Check the condition of the bead Replace if necessary e Verify that the flow settings are correct e Thoroughly leak check the whole system especially the detector column fitting See Checking for Leaks e Set the equilibration time to 0 0 Troubleshooting NPD Low Selectivity Troubleshooting Chroma
43. the column type is correct Perform column maintenance Bake out contaminants remove the contaminated length of column near the inlet and reverse and bake out the column as needed Verify that the liner type is appropriate for the sample Verify that the detector flow settings are correct Check the supply gas purity Check all trap indicators and dates Verify that the method parameters are correct Check sample stability Check configured syringe size Some syringe sizes are specified at half capacity If the maximum syringe volume is marked at half height on the barrel not at the top of the barrel enter twice the labeled volume when configuring the syringe size If using an FID Verify that the correct jet is installed Check for a dirty jet If using a uECD Replace the fused silica indented mixing liner Replace and reinstall column Clean the makeup gas adapter If using an NPD Check the detector for contamination Replace ceramic insulators Replace the bead If using an FPD Verify correct column installation Troubleshooting Chromatographic Symptoms 3 e Check that the correct filter is installed and is clean e Check the flow rates e Check the makeup gas type Troubleshooting 37 3 Chromatographic Symptoms FID Flame Goes Out During a Run and Attempts to Reignite pA oo a oo gt w N 38 The following is an example chromatogram showing a flameout fr
44. the sample is pulled into the syringe e Verify the detector in use is assigned to a signal e Check the column for proper installation e Ensure that the column is not plugged See To Measure a Column Flow Perform column maintenance e Check for leaks See Checking for Leaks e Check the flow settings then measure the actual detector flows See To Measure a Detector Flow If the problem is with the detector see Table 1 Table 1 Detector troubleshooting Detector Solution FID FPD e Verify that the electrometer is turned on e Verify that the flame is still lit TCD e Verify that the filament is turned on e Ensure that the reference gas is not set to zero NPD uECD Verify that the electrometer is turned on Troubleshooting Chromatographic Symptoms 3 Baseline Rise During Oven Temperature Program e Inspect the column for bleed e Check for leaks oxygen in carrier gas supply e Check gas supply oxygen trap indicator or date e Make solvent blank runs to evaluate baseline without sample e Make no injection blank runs remove the syringe from the injector and start a run to evaluate baseline without solvent e Check for contamination See Contamination or Carryover e Consider the effect of column film thickness on bleed e Check for leaks at the column fittings See Checking for Leaks e Prepare and use a column compensation profile Troubleshooting
45. time determined by the type of inlet Do the following e Check for sufficient gas supply delivery pressure The pressure at the supply should be at least 10 psi greater than the desired setpoint e Check for leaks See Checking for Leaks e If using gas saver be sure that the gas saver flow rate is high enough to maintain the highest column head pressure used during a run e Check for an incorrectly installed column If you are using a split splitless inlet PTV inlet or volatiles interface e Check the split ratio Increase the amount of split flow 60 Troubleshooting GC Not Ready Symptoms 4 A Gas Exceeds Pressure Setpoint or Flow If a gas exceeds its pressure or flow setpoint do the following If using a split splitless inlet PTV inlet or volatiles interface e Decrease the split ratio e Replace the split vent filter e Verify that the correct liner is selected for split splitless and PTV inlets e Check the gold seal for contamination for split splitless inlet If using an FID or NPD e Check for a plugged jet Valves e Check for a misaligned rotor Troubleshooting 61 4 GC Not Ready Symptoms The Inlet Pressure or Flow Fluctuates 62 A fluctuation in inlet pressure causes variations in the flow rate and retention times during a run Do the following Check if the gas purifier or gas generator is operating at or near capacity Check the supply gas for sufficient delivery p
46. ting Troubleshooting Tasks 8 To Adjust the FPD Lit Offset To adjust the FPD Lit offset 1 Press Config 2 Scroll to Front detector or Back detector wherever the detector is installed and press Enter 3 Scroll to Lit offset With the Lit offset line highlighted enter the new parameter for the FPD typical value is 2 0 pA and press Enter Troubleshooting 101 8 Troubleshooting Tasks 102 Troubleshooting
47. tographic Symptoms Verify that the hydrogen flow is correct lt 3 mL min Inspect the bead it may be defective or expended Verify correct bead voltage Replace the collector and insulators 49 3 Chromatographic Symptoms Negative Peaks Seen with TCD 50 Verify that the correct gas type is being used Check for a leak in the system especially at the detector column fitting See Checking for Leaks Consider sensitivity to analytes Check the flow settings then measure the actual detector flows See To Measure a Detector Flow Troubleshooting Chromatographic Symptoms TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks Ringing Baseline TCD1 A RINGINGICT_50001 D 25 uv 120 100 380 60 Wrong data rate is selected in the data system For TCD the data rate should be lt 5 Hz Troubleshooting 51 3 Chromatographic Symptoms TCD Peaks Have Negative Dip on Tail e Check for leaks at the detector column adapter fitting See Checking for Leaks e Upgrade the detector to a passivated filament 52 Troubleshooting Agilent 6890N Gas Chromatograph Troubleshooting 4 GC Not Ready Symptoms GC Never Becomes Ready 54 Flow Never Becomes Ready 55 Oven Temperature Never Cools Down Cools Very Slowly 56 Oven Never Heats Up 57 Temperature Never Becomes Ready 58 Cannot Set a Flow or Pressure 59 A Gas Does Not Reach Setpoint Pressure or Flow 60 A Gas Exc
48. ured to a gas other than what is actually being plumbed incorrect flow rates will result 1 Concepts and General Tasks Information to Obtain Before Calling Agilent for Service 10 Gather the following information before contacting Agilent for service e Symptoms e Problem description e Hardware installed and parameters configuration when the error occurred sample supply gas type gas flow rates detectors inlets installed and so forth e Any messages that appear on the GC display e Results of any troubleshooting tests you have run e Press the Status key to display previous Error Not Ready and Shutdown messages To obtain service support contact numbers see the Agilent Web site at www agilent com chem Troubleshooting Agilent 6890N Gas Chromatograph Troubleshooting 2 Hardware Symptoms Plunger Errors 12 Vial Mishandled by ALS 13 Syringe Needle Bends During Injection into Inlet FID Does Not Ignite 15 FPD Does Not Ignite 18 NPD Adjust Offset Process Fails 19 egip Agilent Technologies 14 2 Hardware Symptoms Plunger Errors If the ALS reports a front or back plunger error check the following possible causes e The syringe plunger is sticking or is not securely connected to the plunger carrier 12 Troubleshooting Vial Mishandled by ALS Troubleshooting Hardware Symptoms 2 Refer to the 7683B Automatic Liquid Sampler Installation Operation and Maintenance manual for additional info
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Agilent 6890N Gas Chromatograph Troubleshooting Manual