Dear all,
Just recently my stability tests (6-10 CO2 pulses from tube) have started to
show drifting values sliding both up and down from test to test. Why?

As well it has been necessary to refocus the MS several times last weeks due
to decreasing signal (from 2.4V to 1.5V) at 1.5 bar ref gas pressure.
Normally I do that just a few times a year, but I have been runnig a lot of
samples lately.

My chromatographic internal standard show sliding per mil 13C as well with
several per mil within a batch of runs.

Any ideas why - what to do?

Lars