Preventive Maintenance and Troubleshooting
Chromatographic symptoms
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Injection port septum is giving off volatiles
Make several “blank” runs with a small piece of aluminum foil backing the inlet
septum. If the contamination peaks disappear, they were probably due to the
septum. Try replacing the septum you usually use with another type.
Column is contaminated
High molecular weight samples that contain residues may cause the syringe,
the inlet liner, or the first few inches of column to become contaminated. Do
the following:
• Replace or clean and deactivate the inlet liner.
• Examine the first few inches of a capillary column for foreign material by
holding a light behind it. If possible, remove the contaminated section.
Sample is not stable
Some samples change with heat or ultraviolet light. Check the sample stability.
There are several ways to reduce the change:
• Use the tray quadrants to cool the sample.
• Use amber sample vials.
• Store the samples in a protected environment.
Impurities in the carrier gas
Install a carrier gas trap in the gas line to the GC, or replace the existing trap. If
the gas contains impurities, the contamination peaks gradually disappear once
the trap is installed.
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