For some days, we have been facing unusual Gas Quality fluctuation. Methane showed almost 100% from 92%, Ethane showed almost 0% from 7%, and HHV & LHV also unusually decreased. GC recalibrated multiple times. But still issue persists. Can anybody explain? Which way to check? Thanks in advance.

 

Google could be your friend

illustrated slides:
https://www.agilent.com/cs/library/eseminars/public/GC_Troubleshooting_09072017.pdf

lists:
https://www.thermofisher.com/us/en/...roubleshooting-guides-gas-chromatography.html

And others . . . . .

 

You can expect a reduction in HHV with reduction of you ethane component

 

Gas chromatograph anomalies can be complex. Beyond recalibration, consider sample integrity, system maintenance, or external factors.

 

Even the calibration gas can be off spec, too