We commonly use -ESI for acidic peptides, synthetic carboxy acids, and
phosphates by constant infusion using a mobile phase of 50:50
water/methanol with up to 1% NH4OH. We have also used mobile phase
consisting of aqueous solutions of 10 to 50 mM ammonium acetate, pH~8.3 or
so, that yield somewhat cleaner spectra. FYI, perfluorodecanoic acid
(m/z=514) makes a good calibration compound for lower mass -ESI.
Good Luck,
Lloyd
At 08:55 PM 7/21/99 +0100, you wrote:
> Hi all, I'm interested in analysing acidic peptides in negative ion
>mode. Has anyone done this type of work and could provide some information
>on the best method of analysis (online-LCMS or infusion),buffers etc.
>Thanks Dougie Lamont PPL Therapeutics
Lloyd W. Sumner, Ph.D.
Associate Director, The Laboratory for Biological Mass Spectrometry
Texas A&M University
Department of Chemistry
P.O. Box 30012
College Station, TX 77842-3012
Voice #409-845-8404
Fax #409-845-4719
Email Sumner@mail.chem.tamu.edu
For more information concerning the LBMS
and the Applied MS Lab visit our webpages at:
http://www.chem.tamu.edu/rgroup/russell/
http://www.chem.tamu.edu/services/ms/
For more information on The Center for Chemical
Characterization and Analysis see:
http://www.chem.tamu.edu/CCCA/