Peak area increases with every repeat injection

Hello SeanF ,

You are saying that after a solvent wash the peak is gone. I would like to understand, after your analysis, on your first solvent wash, do you see the peak? And do subsequent solvent washes are clean?

Or is the very first solvent wash clean, with no sign of carryover?

What does the peak shape look like during the analysis: any tailing, fronting, for example?

How is the sample injected (Headspace, Autosampler, Manual)?

Finally, what are you injecting? Is it a standard? And if it is, is it an in-house prepared standard?

Hi CMZainea,

Thank you for your response. Please see below for traces. First one is the overlay of the washes. The second one is the overlay of multiple injections. The acetone wash may have some carryover of the peak, but it is difficult to be certain since the peak shifts a bit. Acetone wash has carryovers of other peaks. There is some tailing for the peak especially when the peak is small. The sample is not a standard. I'm trying to figure out what this peak is. But first of all, I need to make sure this peak is real, not some ghost peak or contamination. I also injected this sample in GC-MS which use the same GC method, but I don't see this peak. But our GC-MS is much less sensitive than our GC-FID. The sample is injected through Autosampler. 

Hello SeanF ,

Have you done the usual maintenance steps on the GC? For example, a bakeout of the inlet, column and the FID? And if you did and it did not fix the problem, did you change the inlet consumables (if applicable) and the FID Jet?  And have you tried this with a new column?

Hi CMZainea,

Thanks for the recommendation. I'll do some maintenance and see if that fixes the problem.

Hi CMZainea,

Thanks for the recommendation. I'll do some maintenance and see if that fixes the problem.