Appropriate choice of carrier gas

[auv9]

I am analysing a gas mixture (CO2, CO, H2 and CH4) using TCD detector, could anyone please suggest me the suitable carrier gas that I should be using? Thank you

[GasMan]

It is important to know the concentrations. For maximum sensitivity, helium should be used as carrier gas, BUT you will have problems with your hydrogen measurement. Hydrogen does not give linear results with helium as carrier gas below about 10%. If you have low concentrations of all of the compounds, you are basically looking at a two channel system, one using helium as carrier gas and the other channel using nitrogen or argon as carrier gas. If all of your compounds are in the % levels you could porbably get away with one channal using argon carrier gas.

Gasman

[Dank]

Yes you can analyze all the molecules except for H2 using He carrier gas and H2 can be analyzed using Ar as a carrier just note when using Ar as the carrier to reverse the polarity of the TCD or else you will end up with a negative peak.