Autotune gcms nitrogen is high

[seet88]

Hi all,

At May I encounter nitrogen bias high, then found out tat dftba vial is empty. Then refill, it look normal after that. However, after one month ltr, nitrogen become 44%. The interface is tighten well. May I know the root cause

Thanks
Seet

[Rndirk]

What about oxygen?

[dblux_]

... May I know the root cause

Thanks
Seet

A leak is the culprit unless you messed up with carrier gas (cylinder, trap).

[Steve Reimer]

Did it appear when a tank was changed?
Helium has been known to have nitrogen in it. Even though you paid for it to be pure.
It could also be a leak between the tank and scrubber if you don't see oxygen.

[Consumer Products Guy]

I'd plug the flow to the MSD and run the tune, see if that reduced the nitrogen. If so, that would isolate the issue to the GC; if not, to the MSD.