FID baseline in dependence of flow

[emsman]

Hello,

I need some support on FID principles. Normally our GCs have about 2-5 pA baseline (FID-detector). Since today there are 70 pA, on all instruments! Searching after the contamination in the gas supply I changed the flow of FID gases:
300 instead of 400 ml/Min Air (from factory net through zero Air Generator) brings about 10 pA decrease in the Baseline
20 instead of 30 ml/Min Hydrogen (from hydrogen generator) brings about 50 pA decrease.
Does hydrogen change the flame processes so much, that baseline goes down that much? I don't know how hydrogen can be contaminated.
Air contamination is more likely (we had that before), but before I make stress in the infrastructure department I want to be sure, that contamination is not self produced by us in the lab.

Thanks a lot in advance
Emsman

[emsman]

Hello,

Problem is gone. There must have been a contamination in air. Baseline is OK again.

Thank You
Emsman

[Chris Jones]

Well that was an easy fix

Amazing what flow-on effects can happen with contaminated gases. See my thread about the baseline woes...