My two cents input:
I have used a spray solution of 50% acetonitrile in .1% acetic acid using angiotensin. I observed predominantly +2 charged and +3 charged species with very small +1 charged species. My angiotension solution concentration is high (6 pmol/ul). I did not try with MeOH solution. But I think it might have something to do with spraying solution used. The heated capillary temperature was 200C in my nanospray case.
Hope it helps.
April Xu
Regeneron Pharmaceuticals, Inc.
--------------------------------------
Len Packman wrote:
> A question for experienced LCQ users:
>
> What's the best combination of parameters (voltages and capillary temp) to
> promote formation of doubly charged ions in nanospray MS? I get quite a few
> singly charged ions in the 1000-2000 m/z range whose 2+ states can be found
> on zoomscan but which are not obvious by inspection of the full scan. What
> tricks favour the higher charge state? I'm spraying in 1% formic acid, 70%
> MeOH.
>
> Len
>
> *********************************************************************
> Dr Len C. Packman
> Assistant Director of Research
> Protein and Nucleic Acid Chemistry Facility
> Department of Biochemistry
> University of Cambridge
> 80 Tennis Court Road
> Old Addenbrookes Site
> Cambridge, CB2 1GA, UK
> Tel: +44 (1223) 333639
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