Has anybody seen oxidation reaction occurred in the electrospray
ionization source? We have been running peptide mapping on HP1100/
Micromass platform LCZ and noticed that one of the peptide known to be
susceptible for oxidation gave +16 and +32 peaks in addition to MH+
peak. Since we know the oxidized form of this peptide elute earlier on
the chromatogram, so these +16 or +32 ions must have been generated
after the column separation. We otherwise would not concern too much
about this as they are really very small peaks, however, now we are in
the process trying to replace the liquid nitrogen tank with one of the
N2 generators. I got information from Domnick Hunter Inc., one of their
N2 generators can give 8000cc/min flow at 100 psi pressure with 99.5%
purity. But the impurities left over would be oxygen as the most, as
they said. Would this be a problem?
I would appreciate any comments on this.
Kate Zhang