Methane method

[cabeto]

Hello everybody

I am new in this forum and working with a GC equipment. I am going to measure methane from the headspace of microcosms with a Varian 3400 and a FID detector.
1. Can anyone tell how should I prepare/dilute the different concentrations for the standard?
2. Is the Poropak Q the most suitable column for methane analysis? Or should I consider another option?
3. Detector temperature 160C, oven temperature 45 C, injector temp 110, do these temperatures sound appropriate for methane analysis?
4. Argon or helium as carrier gas?
Thanks

Carlos

[larkl]

The column and temperatures used are going to depend on the matrix, ie - what else is in the sample?. (Sorry - I have no idea what a microcosm is). There are a number of options for doing methane.

How are you planning to get the sample into the GC? This might help us more on the standards question. If you're going to do a GSV injection, then you're probably going to need a standard blend prepared by a gas vendor.

[cabeto]

I have serum bottles filled with cow manure and organic matter that after couple of days of anaerobic digestion methane will be produced.

I expect that there will production of methane, CO2, VFAs and maybe H2S.

The samples will be taken from the bottle head-space and injected manually using an airtight syringe.

I definitely need to buy a calibration standard and from this commercial available standard make the dilutions.

Thanks,