Hi all,


We are having an issue with our Delta Advantage with HD cups and I was wondering if you might have some clues about it.  Usually after the weekends, when there are no samples running, the intensity (H) of ref gas decrease dramatically (sometimes 80%), then after autofocus the source, this usually brings the intensities back but is kind of unstable. When is stable, we can run for days without an issue.


Yesterday it was quite large decrease (from 6V to 1V in mass 2 for the ref gas), then focusing seem to fix everything to normal intensity but the backgrounds of mass 3 are now negative (these has been decreasing over long time).  However, the signal of the ref gas is kind of good again (mass 2, ~6V, mass 3, ~2V).


Any thoughts on why those decreases of signal and/or negative backgrounds in mass 3?  Thanks so much in advance. 







David X. Soto, Ph.D.

Marie Curie Fellow

KU Leuven

Department of Earth and Environmental Sciences

Leuven, Belgium