Troubleshooting 10
Installation, Operation, and Maintenance 169
Part 3, Maintenance and Troubleshooting
Vial caps are loose. Check vial caps. If you can turn the vial crimp cap by hand,
they are too loose. Loose caps may cause volatile samples to
change concentration over time. See “Capping sample
vials” on page 113.
Sample is not stable. Check the sample stability. Some samples change with heat
or ultraviolet light. There are several ways to reduce changes
to unstable samples:
• Use the tray quadrants to cool the sample.
• Use amber sample vials.
• Store the samples in a protected environment.
Sample size varies. Install a new syringe. If the sample size varies, the syringe is
probably not precise or the plunger is worn. Variation may be
due to syringes with removable needles because of dead
volume or needle-to-needle variation.
Air bubbles are in the needle. If air bubbles are in the needle, increase the run parameter
that controls the number of sample pumps. See “Setting
Injector Parameters on a 6890 GC” on page 87.
If this does not help and the sample is viscous, try the
following:
• Increase the viscosity delay time.
• Use the tray quadrants to warm the sample.
• Dilute the sample in an appropriate low-viscosity
solvent.
Table 2 6 Variability problems (continued)
Possible cause Action
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