Chromatography Forum

Hello,

I was wondering if there's any way to separate and detect CO2 using a GC-TCD with a molsieve column. I know molsieve columns absorb the CO2. Ive read that a shorter 60 cm column might work and we tried this with moderate succes, but my boss is dead set on separating CO2 with a molsieve 15 m column.
Any suggestions?

My specs: Thermo scientific trace 1300 GC, Agilent HP-MOLSIEVE 15 m (actually 14 now, since we cut a meter off) 0.320 mm id, film 25.0 um.

Thanks in advance!

I think you're going to have a tough time with CO2 on a molecular sieve. Your method will have to get to very high temperature to get it out. Why is your boss so set on this? I couldn't find a single app note on the Restek website where they determined CO2 on a molecular sieve column. What else must your method determine and from what matrix?

I never see CO2 on my mole sieve. I use it to get O2 and N2 in air samples exposed to oxygen-absorbing packaging materials (pulsed-discharge helium ionization detector). I know there's CO2 in my samples. It just never comes out (40 deg C). But, I don't really care that it doesn't come out.

Just to echo rb6banjo's comment, what are you trying to separate, from what and in what?

You appear to have a capillary system so you will need a dual column system or a separate column for CO2 analysis e.g.
from the Agilent website
Set of two parallel columns: CP-Molsieve 5Å for permanent gases and PoraBOND Q for CO2 analysis