Re: Mystery peaks from HS Procise 494
Anne Stanley (astanley@psu.edu)
Thu, 29 Apr 1999 12:17:22 -0400
Correction & mea culpa follow up to my previous message....
>I have a 477a sequencer.
>2 weeks ago I had my PITC crystalize on the instrument so I
>changed it to lot 9810014. Meantime ABI sent a fresh replacement
>of PITC (lot 9901019).
> I started having a high background right then, primarily in the area of
>the >"triplet of peaks" that Ken Williams reported in his message. I
>changed
>all my reagents (not wanting to take the time to find the culprit), and
>>switched to the new PITC lot 9901019 that I had just received - the
>background >after this change, although better than with lot 9810014, is
>still higher than >desired (even after I KOH/MeOH cleaned all my lines...)
>I suspect that Ken's culprit may be the late 98 PITC as well, and
>unfortunately >in my hands the 99 vintage is not much better.
I am very embarrassed to say that I found the cause of the artifacts
in my chromatograms and that it was not related to any PITC lots....
Two of my three block cartridges apparently got contaminated during the
same time period with a lot of glycine, Glutamic and Serine, opne of them
with less than the other. When I used to third (uncontaimnated cartridge,
the problem miraculously disappeared. A simple wash with either TFA or
MeohKOH did not clean the contaminated blocks but 30 minutes of sonication
in a 100% TFA did a wonderful job (and according to ABI, nitric acid was
the preferred cleaner, but TFA worked fine in its absence).
Sorry for the "jumped to" earlier conclusion about PITC lots, hope
this sets the record straight.
Anne Stanley
Hershey Medical Center
PennState University