MS
Jim Bloom (Jim.Bloom.B@bayer.com)
Thu, 11 Nov 1999 10:35:23 -0500
When we received our sparkling new single quad ESI-MS seven years ago
we were overwhelmed...wow could we do stuff we had never dreamed was possible!
After about two years of experience we became jaded...just think what we could
do with more sensitivity, accuracy, resolution and if only we could sequence
those peptides in the map on-line!! So, we are now in the position that we
will be able to upgrade sometime in the forseeable future and I notice that the
times have changed. In the "old days" we would purchase a triple quad. Triple
quads now seem to be passe' and the ion trap has become the work horse. The
new kid on the block seems to be the orthogonal ESI/TOF. So what to do...what
to do? I have talked to a trusted vendor of ion traps and was told that if we
have the money we should buy an othogonal ESI/TOF. We have arrived at the
subject of this email. Two vendors sell ESI/TOFs: Micromass with their QTOF
and QTOF2 and PE SCIEX and their QSTAR. I am convinced that both companies
sell instruments that we would be happy with...however there are always pros
and cons and I would appreciate any input regarding the following questions:
1.) Most of the hype revolves around differences in resolution, 5,000
vs 7500 vs 10,000 etc. In practical terms, is the difference between 5,000 and
7,500 significant...how about 5,000 vs 10,000 (I see one can pay an extra
$100,000 for the difference).
2.) We are buying an instrument to do sequencing...we have no
experience doing MS sequencing...I am told the correct software will make or
break us. I am told that one vendor has had excellent software for years and
the other has not quite released theirs yet. Should we go for the vendor with
the software (a bird in the hand is worth two in the bush)?
3.) How about the intangibles...service, support, robustness etc....
Does one vendor stand out in these areas?
4.) Perhaps the ion trap vendor was being too modest and we should buy
an ion trap??
5.) Finally, assuming we buy a fancy new machine should we dispose of
our trusty old single quad? Reading the mail I see that we may want to keep it
so that we can continue to do the classic "Steve Carr" method of SIM analysis
to figure out which peak in our peptide map contains glycosylated peptides.
Weather inconsequential: the Bay area got its first significant rain for the
season a few days ago and I turned off the automatic sprinklers for the back
yard (another gopher/mole season comes to an end).
Jim Bloom
Bayer Corp
Berkeley
510-705-7760
jim.bloom.b@bayer.com