Hiya Paul,

> I'm hoping someone can shed some light on a problem I am having
(GC-IRMS,
> MAT252). My background levels for CO2 are elevated, but on masses 45 and
46
> only. The source seems to be my Nafion trap, as the 45 (and 46) signal
> increases drastically (perhaps 200mV) when I heat the trap, and falls to
> normal when the trap is removed. Mass 44 is unaffected throughout all of
> this (~9mV).

Have you tried doing a broad mass scan, from 30 up to 60, to see if any
other peaks exist?  These might help by giving as a mass signature to work
on.

It could possibly be an organic contamination of some type, which has got
stuck in the Nafion trap and associated tubing.  The 44 signal could then
be increasing by the same amount, but has only 1/100th the sensitivity, so
would appear as 2mV for what would would look like 200mV on the 45
collector.  If you see a huge 43, 41 and 39, it's nasties!

Andrew