Baseline problems - offset

GC Technical Tip
Level: Intermediate

In this month's technical tip we look at an issue that may occur before you start your gas chromatography run - how to solve offset baseline issues, where sudden unexplained changes in baseline position are seen.

The table below outlines the most common offset baseline problems you may encounter.

Symptom

Possible Cause

Suggested Remedy

Offset

Line voltage changes.

Monitor line voltage for correlation with offset. If correlation is found, install voltage regulator.

Poor electrical connections.

Check electrical connections. Tighten any loose connections. Clean any dirty or corroded connections.

Contaminated injector.

Clean injector. Replace inlet liner. Replace glass wool. See injector maintenance.

Contaminated column.

Cut off the first 4 inches of column. Bake out the column. Replace the column.

Column inserted too far into the flame of FID, NPD, or FPD detectors.

Reinstall the column. Be sure to insert the column into the detector exactly the correct distance specified in the instrument manual. See column installation.

Contaminated detector.

Clean the detector. See detector maintenance.

Gas generator.

Baseline fluctuations can arise if the gas generator's supply pressure regulator isn't working correctly. For systems with long supply tubing, installing a step-down regulator near the GC system might be necessary. Additionally, an extra regulator can help smooth out fluctuations caused by gas generators.

See you next month for another tip! In the meantime, explore our range of Zebron™ GC columns and application-specific proprietary phases.