Chromatography Forum

Hello,

I need to seperate various compounds by GC and I don't really know which kind of column to choose. I have different classes :
1) alcohol (Methanol)
2) aldehyde (formaldehyde)
3) ethers (dimethyether and dimethoxymethane)
4) ester (methyl formate)
5) CO and CO2

If someone has an idea about how to separate all these organics, I'm really interested.
Thanks in advance

jrmy

A glass porapak Q column 3 meters in length might be a good place to start as you want to separate gases from liquids and gases from each other. You will have to program temperature the column in any case with all the analytes you have listed with any column.

Di-methoxy-methane might be too unstable to chromatograph in the presence of alcohols and aldehydes.

If you wish to use capillary, then a 1701 thick film 0.53mm column or a thick film Wax 0.53mm column might be a good starting place, but you won't be able to separate CO from CO2 unless you have a subambient oven.

best wishes,

Rod

Jrmy,

Curious, what levels and what detector? The one that has me intrigued is the formaldehyde.

Best regards.

So, for the moment, I have 2GC, each one with 1 TCD and 1FID. The whole system is connected to a sampling loop system which enables injection in the 4 columns simultaneously.
Everything is in gas phase, the goal is to study the oxidation of methanol an formadehyde is the first degradation product. I work about 8% MeOH in vol.

I tried to separate on a TC-FFAP capillary column (FID). It separates DME/DMM/MF/MeOH. But I don't know where is formadehyde. Moreover, peaks aren't symetric and products are retained (ex : MeOH remains 2min on the column before joining the baseline).

Thanks for your propositions

Best regards

Formaldehyde has a poor response to a FID. You should use TCD for CH2O.

best wishes,

Rod

Would you be so kind as to post some chromatograms of your work?

It would be interesting to see what separations you have achieved.

best wishes,

Rod