> Marching Background? That sounds like polymer contamination. If you have
> shot detergent containing samples on the system that could explain the
> background. Also PEGs and other ethoxylated polymers give +44 ion series.
> The 'PEG's could also be from the water. Or extracted polymer from
plastic
> ware/silicon coatings.
And what about a +59 ion series? I'm using acetic acid in a 5%
concentration. 59 Da is the mass of the acetate ion. But how acetate
interact with the peptide? Is it possible to have acetate polymerization?
There is another explanation for the +59 ion series?
Best regards.
-------------------------------------------------------
Prof. Ricardo B. Cunha
Brazilian Center for Protein Research and Services - CBSP
Laboratory of Protein Chemistry and Biochemistry
Institute of Chemistry
University of Brasilia
Brasilia - DF Brazil
ZIP CODE: 70910-900
Tel: 55-21-61-307-2142
Fax: 55-21-61-272-4548
mailto:rbcunha@unb.br
http://www.geocities.com/Athens/Acropolis/5221
http://www.unb.br/cbsp
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