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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!
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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 !
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By chromatographer1 on Wednesday, August 11, 2004 - 01:55 pm:
This should not be a problem at low temperatures (below 50°C). 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?
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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!
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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.
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!
-------------------------------------------------------------------------------------------------------
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 !
-------------------------------------------------------------------------------------------------------
By chromatographer1 on Wednesday, August 11, 2004 - 01:55 pm:
This should not be a problem at low temperatures (below 50°C). 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?
-------------------------------------------------------------------------------------------------------
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!
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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.
