Any other similar experiences out there?
Anne Stanley
Hershey Medical Center
PSU
A triplet of peaks has suddenly appeared on the HPLC chromatogram from our
HS Procise 494 that we cannot seem to rectify - any help/ideas would be
greatly appreciated. Here are the clues to this puzzle:
1. the first two peaks co-elute with Pth-Gly and Pth-Glu with the third
eluting between Pth-His and Pth-Ala. By comparison to the standards the
relative "pmol" amounts of these peaks are about 0.5 pmol (Gly), 2 pmol
(Glu) and 1 pmol (X).
2. these peaks appeared following addition of several new reagents to the
instrument - all of which have subsequently been changed again.
3. the peaks are present at the same level in all cycles and the instrument
is still sequencing normally.
4. the peaks are present also in the blank cycle.
5. the flask has been KOH washed and the column guard has been changed
without effect
6. the Pth column is 4 weeks old while this problem occurred suddenly a few
days ago
Currently, our efforts are directed towards watching a blank cycle to be
sure all wash steps are indeed occurring and then, to deleting steps from
the wash cycle program until we isolate the step or reagent causing these
peaks.
If you have seen these peaks previously and/or have any ideas on their
origin or how to more effectively diagnose the problem please respond.
Thanks very much,
Ken Williams