Troubleshooting Guides


Excessive Baseline Noise Possible Cause


Injector contamination Column contamination


Detector contamination


Contaminated or low quality gases Column inserted too far into the detector


Incorrect detector gas flow rates Leak when using an MS, ECD, or TCD


Solution


Clean the injector; replace liner, gold seal Bake-out the column


Solvent rinse the column Clean the detector


Use better grade gases; also check for expired gas traps or leaks


Reinstall the column


Old detector filament, lamp or electron multiplier Replace appropriate part Septum degradation


Replace septum


Baseline Instability or Disturbances Possible Cause


Injector contamination Column contamination


Unequilibrated detector Incompletely conditioned column


Change in carrier gas flow rate during the temperature program


Tailing Peaks Possible Cause


Column contamination Column activity Solvent-phase polarity mismatch


Solvent effect violation for splitless or on-column injections


Too low of a split ratio Poor column installation


Some active compounds always tail Comments


Try a condensation test; gas lines may also need cleaning


Limit the bake-out to 1-2 hours


Only for bonded and cross-linked phases Check for inlet contamination


Usually the noise increases over time and not suddenly


Usually occurs after changing a gas cylinder Consult GC manual for proper insertion distance


Adjust the flow rates to the recommended values Consult GC manual for proper flow rates Find and eliminate the leak


Usually at the column fittings or injector


For high temperature applications use an appropriate septum


Solution Clean the injector Bake-out the column


Allow the detector to stabilize Fully condition the column


Normal in many cases Comments


Try a condensation test; gas lines may also need cleaning


Limit a bake-out to 1-2 hours


Some detectors may require up to 24 hours to fully stabilize


More critical for trace level analyses


MS, TCD and ECD respond to changes in carrier gas flow rate


Solution Trim the column Solvent rinse the column Irreversible. Replace the column


Change sample solvent to a single solvent Use a retention gap


Decrease the initial column temperature Increase the split ratio Reinstall the column


None Comments Remove 0.5-1 meter from the front of the column


Only for bonded and cross-linked phases Check for inlet contamination Only affects active compounds


More tailing for the early eluting peaks or those closest to the solvent front


3-5 meter retention gap is sufficient Peak tailing decreases with retention


Flow from split vent should be 20 mL/min or higher


More tailing for the early eluting peaks Most common for amines and carboxylic acids


150


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