ABRF Electronic Discussion Group viewed: Re: MS

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your question is not that easy to answer.=20
We have a API3000 and since 10 weeks now the new PE Sciex QStar =
qadrupole-TOF system. If the main purpose of your instrument to buy was =
de-novo sequencing, I would say it must be a quadrupole-TOF system for =
the reasons you have mentioned. Doing this with a triple-quadrupole =
sytem would be more than challenging. You need at least a good =
resolution (as with an ion trap) but better both good resolution and =
mass accuracy.
But you also mentioned, that you want to do mapping of posttranslational =
modifications like phosphorylation and glycosylation. As you need =
precursor ion scanning ability on your system for this application, you =
have to choose a triple-quad. As to my knowledge, both quadrupole-TOF =
systems (Micromass and Sciex) don=B4t have this ability at the moment. =
Our QStar has the option in the software, but on hardware-side (resp. =
both sides...) it is not working at the moment. But they told me, that =
they are working on that.
So, to come to an end, as we had the money to buy both types of =
machines, we did it. The QStar is used for peptide (de-novo) sequencing, =
the API3000 for peptide sequencing, mapping of posttranslational =
modifications and will be used for peptide quantification.
Maybe it=B4s a good idea to ask Sciex and Micromass what they are intend =
to do on the field of precursor ion scanning ? Hope that helps.=20

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Dr. Michael Juergens
Head of Mass Spectrometry
BioVisioN GmbH & Co. KG
Feodor-Lynen-Strasse 5
D-30625 Hannover
Germany

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We have a API3000 and since 10 weeks now the = new PE Sciex=20 QStar qadrupole-TOF system. If the main purpose of your = instrument to=20 buy was de-novo sequencing, I would say it must be a quadrupole-TOF = system for=20 the reasons you have mentioned. Doing this with a triple-quadrupole = sytem would=20 be more than challenging. You need at least a good resolution (as with = an ion=20 trap) but better both good resolution and mass accuracy.

But you also mentioned, that you want to do = mapping of=20 posttranslational modifications like phosphorylation and = glycosylation. As=20 you need precursor ion scanning ability on your system for this = application, you=20 have to choose a triple-quad. As to my knowledge, both quadrupole-TOF = systems=20 (Micromass and Sciex) don=B4t have this ability at the moment. Our QStar = has the=20 option in the software, but on hardware-side (resp. both sides...) it is = not=20 working at the moment. But they told me, that they are working on=20 that.

So, to come to an end, as we had the money to buy = both types=20 of machines, we did it. The QStar is used for peptide (de-novo) = sequencing, the=20 API3000 for peptide sequencing, mapping of posttranslational = modifications and=20 will be used for peptide quantification.

Maybe it=B4s a good idea to ask Sciex and Micromass = what they=20 are intend to do on the field of precursor ion scanning ? Hope that=20 helps.

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