Agilent Technologies 6890N Operating instructions

Agilent Technologies
Agilent 6890N
Gas Chromatograph
Troubleshooting

Notices
© Agilent Technologies, Inc. 2007
No part of this manual may be reproduced
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Manual Part Number
G1530-90011
Edition
March 2007
Printed in USA
Agilent Technologies, Inc.
2850 Centerville Road
Wilmington, DE 19808-1610 USA
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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.
WARNING
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.

Troubleshooting 3
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 the source 24
Check possible causes—all inlet and detector combinations 24
Larger Peaks Than Expected 25
Peaks Not Displayed/No Peaks 26
Table 1. Detector troubleshooting 26
Baseline Rise During Oven Temperature Program 27

4Troubleshooting
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, > 20 pA 44
NPD Solvent Quenching 45
NPD Response Low 46
NPD Baseline Output > 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
Flow Never Becomes Ready 55

Troubleshooting 5
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 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

6Troubleshooting
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 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

7
Agilent 6890N Gas Chromatograph
Troubleshooting
Agilent Technologies
1
Concepts and General Tasks
Concepts 8
Configurable Items to Always Keep Current 9
Information to Obtain Before Calling Agilent for Service 10

8Troubleshooting
1Concepts 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
Use the following steps as a general approach to
troubleshooting:
1Observe the symptoms of the problem.
2Look up the symptoms in this manual using the Table of
Contents or the Search tool. Review the list of possible causes
of the symptom.
3Check each possible cause or perform a test that narrows the
list of possible causes until the symptom is resolved.
The [Status] key
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.

Concepts and General Tasks 1
Troubleshooting 9
Configurable Items to Always Keep Current
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
Reconfigure the GC every time the gas type is changed. If the GC
is configured to a gas other than what is actually being
plumbed, incorrect flow rates will result.
WARNING 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.

10 Troubleshooting
1Concepts and General Tasks
Information to Obtain Before Calling Agilent for Service
Gather the following information before contacting Agilent for
service:
•Symptoms
•Problem description
•Hardware installed and parameters/configuration when the
error occurred (sample, supply gas type, gas flow rates,
detectors/inlets installed, and so forth)
•Any messages that appear on the GC display
•Results of any troubleshooting tests you have run
•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.

11
Agilent 6890N Gas Chromatograph
Troubleshooting
Agilent Technologies
2
Hardware Symptoms
Plunger Errors 12
Vial Mishandled by ALS 13
Syringe Needle Bends During Injection into Inlet 14
FID Does Not Ignite 15
FPD Does Not Ignite 18
NPD Adjust Offset Process Fails 19

12 Troubleshooting
2Hardware Symptoms
Plunger Errors
If the ALS reports a front or back plunger error, check the
following possible causes:
•The syringe plunger is sticking or is not securely connected
to the plunger carrier.

Hardware Symptoms 2
Troubleshooting 13
Vial Mishandled by ALS
Refer to the 7683B Automatic Liquid Sampler Installation,
Operation and Maintenance manual for additional information.
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).
•Check that they are the correct size.
•Verify that the labels do not interfere with the gripper.
•Check that the tray quadrants are clean and snapped into the
tray base.

14 Troubleshooting
2Hardware Symptoms
Syringe Needle Bends During Injection into Inlet
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.
WARNING When troubleshooting the injector, keep your hands away from
the syringe needle. The needle is sharp and may contain
hazardous chemicals.

Hardware Symptoms 2
Troubleshooting 15
FID Does Not Ignite
•Check that the FID ignitor glows during ignition sequence.
(See To Verify FID Ignitor Function During Ignition
Sequence.)
•Verify that the Lit Offset is < 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
(>150 °C).

16 Troubleshooting
2Hardware Symptoms
FID Ignitor Does Not Glow During Ignition Sequence
1Remove the detector top cover.
2Turn the FID flame On.
3Observe 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:
•The ignitor may be bad; replace the ignitor.
•Detector temperature is set to < 150 °C. Agilent recommends
operating the FID at > 300 °C.
•The ignitor is not making a good connection to the ground:
•The ignitor must be tightly screwed into the FID castle
assembly.
•The three T-20 Torx screws that hold the collector
assembly in place must be tight.
•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.
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.
T-20 Torx screws (3)
Ignitor
Knurled nut

Hardware Symptoms 2
Troubleshooting 17
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.

18 Troubleshooting
2Hardware Symptoms
FPD Does Not Ignite
•Check that the FPD temperature is high enough for ignition
(> 150 °C).
•Check FPD flow rates and that they match the type of filter
installed in the FPD.
•Measure the actual detector flows. (See To Measure a
Detector Flow.)
•The column may be installed too high into the detector.
•Check that the FPD ignitor operates. (See To Verify That the
FPD Flame Is Lit.)
•Check the column and makeup flow rates.
•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.
•Check the Lit offset value. The typical Lit offset value is 2.0.
•Thoroughly leak check the whole system. (See Checking for
Leaks.)

Hardware Symptoms 2
Troubleshooting 19
NPD Adjust Offset Process Fails
•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.

20 Troubleshooting
2Hardware Symptoms