please help , choosing column

[badiss]

Hi all
I am doing a research on biogas production, what is the suitable column for detecting biogas ( methane ,CO2 , trace of H2S , H2O ) and volatile fatty acid VFA (C:1-6 ) in wastewater
Knowing that the GC is GC sp-6890 has TCD and FID.
Packed column: 5% SE-30 chromsorbw Aw Dmcs Chromosorb 60-80 mesh Ф3mm × 1.5 m Stainless steel column, carrier gas N2, H2, air
Or Capillary column: column length 30m, inner diameter 0.0.53mm, film thickness 1.0um, stationary phase SE-54, the maximum temperature of 300 degrees)
or other ? can i detect both of them the same time , with the same column?

The biogas sample are in a gas meter (water replacement method) how can inject the sample in GC? Use needle or tedlar bag or …? How to inject gas phase sample in the GC injector?

thanks

[chromatographer1]

Your columns are not suitable for the analysis you seek.

Use a Porapak Q 80/100 mesh for the packed column to the TCD with H2 carrier to measure air CO2 H2S (possibly), and water.

Use a FFAP capillary to measure C1-6 VFA with the FID but you will not detect formic acid. Or use the TCD and detect formic acid in larger amounts.

best wishes,

Rodney George

[badiss]

thanks for your help

[AICMM]

Badiss,

Keep in mind that Rodney's column combination will mean that you will need to support two injectors. Also, look throughout the forum for suggestions on injections. Most of the time people use a gas sampling valve which can be used with needles or tedlar bags. One alternative is to use rubber bladders is your sample has enough pressure to fill it. I have seen this technique used to measure flue gases (CO, CO2, N2).

Best regards.