Chromatography Forum

I'm getting started with some research in a lab using a new GC-FID. To get started, I thought I would try and construct some calibration curves. I decided to start with Methane so that I can get a feel for the unretained times also.

The sample I am running is just methane in nitrogen, but I keep getting two spikes on my chromatogram. I ran the sample through GC-MS to try and figure what the second one is, but the GC-MS only gave me one carbohydrate spike - Methane.

I also ran a sample of just nitrogen to make sure it wasn't anything inside the GC-FID, and there was no response.

Any impurities in the sample should have shown up in the GC-MS, and any impurities in the equipment should have shown up when I ran a sample of nitrogen. Does anyone have any ideas?

What was the source of your methane and how big was the second peak on the FID? What mass range were you using on the GC/MS?

Unless you are using one of the very pure grades of methane, espect traces of other stuff in it.

Just for the record: Methane is a hydrocarbon, not a carbohydrate.