54 Agilent 7890 Series Troubleshooting
3 Chromatographic Symptoms
Peak Boiling Point or Molecular Weight Discrimination Poor
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. Use a liner optimized for split analysis—one
that contains glass wool or other surface area packing to
allow complete sample vaporization.
• 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, MMI, 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. Use a liner optimized for splitless analysis
(deactivated, large volume).
• 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, MMI, PTV, and VI.
• Check that the solvent vapor volume does not exceed the
liner capacity.
• Check for appropriate purge delay time. (Liner
volume/column flow)
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