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- Posts: 67
- Joined: Wed Jun 10, 2009 9:41 pm
- Location: Burlington, Ontario, Canada
I also have a question about analyzing for hydrogen using a TCD and argon. I have set up my ancient HP5890 Series II GC (works great by the way) with a TCD and have optimized it for O2, N2 using helium and a mol sieve column. I presume I can use it for other permanent gases. I can only detect pure hydrogen with a very poor response and as a negative peak using helium which I expected so decided to switch to argon. I don't have a problem with negative peaks. My software can integrate them so that's not the problem.
The problem is that I found as soon as I switched the carrier gas to argon, I could not increase my column head pressure at all from essentially 1 PSI, which seems to also be a baseline if I were to shut down the helium. It had been 5 PSI for helium. I know argon is a heavier molecule and runs would take longer but this was a total surprise to get nothing registering or be able to adjust.
I also do not register total flow for the split valve or the the septum purge although no problems with helium. I can measure a flow through the column (I think unless it was some residual helium or something) depending on how much I open up the reference flow.I don't have electronic flow sensing on this instrument and not sure if there is something in the software (using Agilent Chemstation ver B.01XX) that I need to adjust for the argon.
Can anybody give me a reason why? I have no experience with argon...plenty with hydrogen and helium.
Thanks.
cmoral