We are working with a Gasbench II connected to a 253Plus and since a
couple of month ago the signal has become very unstable.
I got suspicious because my linearity for d18O is much higher than
recommended by thermo (is:0.12 %o/V [should:0.05%o/V]) and every once in
a while the signal changes over one order of magnitude for a short
period of time.
Sometimes I even lose almost all of the signal over night and will have
to refocus to get it back to where it was before.
Also, measurements through the dual inlet show an irregular behavior
leading me to think that there might be a malfunction in the electr.
control unit or a dirty source and not something in the Gasbench itself.
We checked water (m/z18 below 1V)and the system seems to be leak-free.
The filament is rather new, box and trap appear to be stable. We run it
with a current of 1.5mA
Did anyone of you have had a similar experience with his/her 253 or has
heard of a malfunctioning source control unit?
Insitut für Umweltphysik
Im Neuenheimer Feld 229
69120 Heidelberg - Germany