GC for purity analysis

[basiluthuppu]

Hi, I am trying to measure the purity of Helium (almost 99.99% v) using GC - TCD with Argon as carrier gas, Molsieve 5 A column. Trying to make a calibration curve. Can anyone help me to understand reasons for comparatively reduced responses, eventhough the big thermal conductivity differences between Ar and He? How to improve it?

[HPLC chemist]

Why are you trying to perform related substances on gases which are a 'processing aid'? If you have manufacturing problems why not just use a higher purity gas (like 99.9995%)?

As I recall, gas chemists would take the nanoliter injector out of the loop and inject directly from the gas bag 1 or 10 mL. Ask Maxxum Analytics for a method!

[mckrause]

Takes a special purged sampling valve. You don't really analyze the He; you analyze for the impurities. You'll never get there with a TCD; you need to see low ppm levels of Ar, O2, CO2, N2, etc. Use He as your carrier so that you eliminate the He peak.

[HSH]

Hello my friends,

This is my first post. I have a few questions.

I want to probe emissions at high temperature (1400-1900K).
As you know, it is important to sample carefully because it is very likely that radicals decompose immediately at this range of temperature. I have looked at the techniques for gas sampling; however, I do not know which one is proper for using yet. Could you please recommend the appropriate technique?

I think it might be necessary to cool down radicals immediately after probing in order to prevent radical degradation. Do you think using aerodynamic nozzle is a good choice? Do you have any suggestion for this?

Thanks in advance for your help. I am waiting for your response.