We would like to analyse Argon, Neon, Helium and Hydrogen concentration in natural gas samples. I have seen application note using Molsieve column. Could you please suggest suitable columns for this analysis. The sample contains percentage level concentration of CO2.
Hi bijishnair,
a tricky one you have here. First you need a column switching system, a molecular sieve column would be poisoned by CO2 and C2+ and you would loose the permanent gas separation.
You didn't mention oxygen, but if it is present then O2 and Ar will be a critical peak pair and He/Ne is even more critical. To separate this two pair you need a 50 m x 0.53 mm Molsieve 5A column with a layer thickness of 50 µm (CP7539) or a 50 m x 0.32 mm x 30 µm (CP7540)! For carrier gas you left only nitrogen.
The first column should be a porous Q polymer like PoraPLOT Q, the very first peak eluting from this column contains all components you want to analyze, everything eluting later can go to vent.
This first peak is cut onto the Molsieve 5A column and analyzed there.
As some examples we have application note A01272 (switching system with valve, but you can use Deans switching also) and A00764 (He/Ne, Ar/O2 separation).
We test the 50 m x 0.32 mm x 30 µm M5A with the critical peaks and a test chromatogram looks like this:
But it is done with hydrogen, nitrogen as carrier gas will give you a higher plate number but also more peak broadening through diffusion.
Play around, the temperature needs to be as low as possible, the carrier gas flow in the optimum.
Regards,
Norbert
