Chromatographic Symptoms 3
Agilent 7890 Series Troubleshooting 67
Low Peak Area or Height (Low Sensitivity)
• If using an inlet in split mode, check the split ratio.
• Check for leaks. (See “Checking for Leaks”.) To troubleshoot
small leaks in a multimode or split/splitless inlet, see To
Check for Leaks in a Split/Splitless Inlet or To Check for
Leaks in a Multimode Inlet.
• 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 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.
Measure the actual detector flows. If an actual flow does not
match the GC display, check for contamination and
restrictions, for example a plugged jet. See the following:
• To Measure a Detector Flow
• To Check for a Plugged FID Jet
• To Check for a Plugged NPD Jet
• Check the supply gas purity.
• Check all trap indicators and dates.
• Verify that the method parameters are correct.
• Some samples change with heat or ultraviolet light. 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 the drop in peak area or height happened gradually due to
baseline rise, rather than a sudden change, check for
detector contamination. Bakeout the detector (FID, TCD,
uECD).
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