Moisture and O2/N2 testing down to low ppm levels

[pacerlaser]

I have an Agilent 6890N set up with a PDHID. I was trying to set up a method for fixed gas analysis using a packed column but never achieved linearity for O2 and N2. I then switched to moisture analysis using a Stabilwax column but also found that there was no linearity due to a constant background of moisture in the air. Even the act of piercing the GC septum with a gas tight syringe and not injecting anything would result in a moisture peak of about 30,000 area counts. So my question is this, what type of sample introduction equipment would I need to be able to calibrate for fixed gases and moisture down to the low ppm levels? We basically need to test for these analytes in a fluorocarbon mixture to provide a CofA. TIA.

[AICMM]

Pacerlaser,

At least superficially, you answer seems to lie in an injection valve. Are your samples gases or liquids because the recommended valve would change according to your answer.

Water is an ugly one to begin with but I have recently looked at water/ammonia and it was a reasonably doable analysis.

Best regards,

AICMM

[pacerlaser]

Thanks for the reply. We have installed a gas sampling valve to inject the samples into our GC. The issue I am having now is the moisture standard gives inconsistent response. I'm thinking I need to heat the sample transfer line that gets attached to the cylinder that goes into the 6 port GSV. Is there an easy way to heat the sample transfer line? It is only 1/16" in diameter about 3 feet long.