170 User Information
Troubleshooting and Error Messages
Poor area count reproducibility
Poor area count reproducibility results from changes in the
amount of sample reaching the GC detector. Check these
general areas:
The sample vial
Check the vials that contain the samples that show low area
counts. Look for cracks, defective seals, and poor crimps.
The GC
• Verify that the GC works properly. If possible, mount an ALS
over the inlet and inject a sequence of internal or calibration
standard directly into the inlet. Check the area count
reproducibility.
• If Check for Ready is set to “5890 Wait” or “APG Wait” vial
equilibration times may vary. Increase the GC Cycle Time or
select a different Check for Ready setting.
The equilibration of the sample vial
• Poor choice of equilibration temperature or time. For the best
reproducibility, the analytes in the sample and in the
headspace of the vial must reach static equilibrium. Increase
the equilibration time (see page 55) and/or increase the oven
heated zone temperature (see page 52).
• If the sample is a liquid, try adding shake to speed up
equilibration. See page 57.
Sample preparation
Check for inconsistent sample preparation technique and vial
cap crimping.
medium_standard.book Page 170 Tuesday, February 17, 2004 10:14 AM
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