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GC Technical Tip
Level: Intermediate
Baseline problems - offset
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 Zebronâ„¢ GC columns and application-specific proprietary phases.
GC Troubleshooting Guide
The complete guide to GC troubleshooting with hints, tips, and tricks for chromatographic remedies.
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Phenomenex is a technology leader committed to developing novel analytical chemistry solutions that solve the separation and purification challenges of researchers worldwide