Hydrogen and carbon monoxide peaks in Porapak Q

Chromatography Forum: GC Archives: Hydrogen and carbon monoxide peaks in Porapak Q
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Hakan Olcay on Tuesday, August 10, 2004 - 07:38 am:

Hi!

I am trying to separate hydrogen and carbon monoxide peaks in GC. Currently I am using Porapak Q column (6') and could not achieve this. Can I manage this by replacing the column with a longer Porapaq Q column, 12' for instance? Thank you!


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Manuel on Wednesday, August 11, 2004 - 02:15 am:

The problem is, that if you double the length of column, your resolution will only perform by the factor 1,41 (sqareroot of 2 !).
Try a combination of Poraplot U (10 m) and Poraplot Q (10 m), connected with a Butt Connector and the proper ferrule (e.g. Supelco)!
One column is good for polar analytes, the other for unpolar analytes !
We can separate a lot of VOC's (also gases) with this combination !


Top of pagePrevious messageNext messageBottom of pageLink to this message  By chromatographer1 on Wednesday, August 11, 2004 - 01:55 pm:

This should not be a problem at low temperatures (below 50C). How fast is your flow rate?.... slow it down to 10cc/min (2mm ID column) or to 5cc/min (1mm ID column).

BTW what detector are you using and what sample size?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Hakan Olcay on Friday, August 13, 2004 - 07:22 am:

I am using nitrogen as the carrier and its flowrate is about 20 cc/min. GC is equipped with TCD detector. My sample size is 250 microliters. Again thank you for your contributions!


Top of pagePrevious messageNext messageBottom of pageLink to this message  By mattsol on Tuesday, August 24, 2004 - 12:36 pm:

You can use a molsieve 5A packed or capillary column to resolve hydrogen, nitrogen, oxygen, carbon monoxide and methane. Helium and hydrogen co-elute, as do oxygen and argon, but if you know that none of you samples will contain these combinations, the column works well.


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