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Carrier gas
Posted: Mon Oct 27, 2014 10:47 pm
by swara2604
I am kind of new to chromatography so my question may be like too basic..but I am not getting an answer to this..
Can H2 be used as carrier gas with TCD detector if H2 is also one of the components to be measured?
If yes how H2 in carries gas doesn't affect H2 in process gas measurement?
Re: Carrier gas
Posted: Tue Oct 28, 2014 11:55 am
by GasMan
You cannot use a carrier gas for TCD if you wish to measure that compound in your sample. If you wish to measure hydrogen, then use nitrogen or argon carrier gas, providing these are not in your sample.
Gasman
Re: Carrier gas
Posted: Tue Oct 28, 2014 3:37 pm
by rb6banjo
GasMan is absolutely correct.
For the newbie, you may like to know why. TCD relies on measurement of the difference between the thermal conductivity of the carrier gas and the gas containing the analyte(s). If you did your analysis with H2 as the carrier, there would not be a measurable difference between the thermal conductivity of the gas containing your sample injection and the gas flowing through the reference cell (straight carrier gas) in the TCD. It'd be flat baseline in the region of your chromatogram where hydrogen elutes, pretty much no matter what concentration of H2 was in your sample.