Dear Bart,
if you use alpha-cyano as a matrix for sodium containing solutions, you
should cross-check the solutionĄs pH. From our experience, previously
buffered solutions are often not acidic enough (< pH 2). But I would suggest
another solution: use sinapinic acid (5-10 mg/mL 50% acetonitril/0,1% TFA).
Even if your pH is close to neutral, sodium adducts should vanish. But donĄt
work too concentrated because than you get a +206 adduct from the matrix (if
you donĄt like adducts at all ;->).
Greetings,
Michael
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> -----Urspr¸ngliche Nachricht-----
> Von: Bart Haigh [SMTP:bart.haigh@ipd-discovery.com]
> Gesendet am: Freitag, 25. August 2000 16:53
> An: Recipients of ABRF List
> Betreff: Na adduct in Maldi
>
> I have been using a synthetic peptide (nh2) RVYIHPFHL (cooh) in a reaction
> mixture which contains .2M Na+Po4 and have been unable to dialyze the
> sodium out or exchange it with K+.
> I always get a 100% modified peptide with + 22 when glucose is added to
> the mixture and only a small amount of the +22 adduct when no glucose is
> in the mixture . I have been using alpha-cyano as a matrix and have heard
> it may contain sodium but the extent of sodium modification of the peptide
> without glucose is far less than with glucose . I was wondering does
> anyone know of a sure way to displace the Na+ to allow us to be sure it
> is a sodium adduct (unfortunately we can not run the reaction without
> sodium it must be removed afterwards). Thanks for any help,
>
> Bart Haigh
>
>
>
>
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