GC Baseline Drift After Calibration

Category: Analyzer · Gas Chromatograph · Calibration

Plant / Environment

Refinery – Continuous analyzer shelter

Problem Statement

After routine calibration, the GC baseline started drifting slowly, affecting measurement accuracy and analyzer reliability.

Observed Symptoms

• Baseline drift over time
• Unstable detector response
• Frequent recalibration required

Root Cause

Moisture ingress into the sampling system during calibration introduced instability in detector response. The issue was not related to detector electronics or column health.

Corrective Action

• Dried and purged the sampling lines
• Verified sample conditioning and filters
• Stabilized pressure before recalibration

Lessons Learned

• Never recalibrate before stabilizing the sampling system
• Baseline drift usually indicates upstream issues
• Moisture is a silent GC killer