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How about basic buffers in positive mode?
Posted: Mon Dec 01, 2008 10:50 pm
by Anna01
How about adjusting the pH to below 8-9, and operate the MS in positive mode? Possible or just poor ionization effiency? I am working with neutral compounds with low ionization effiency, but want to get rid of interfering substances.
Or could I adjust pH of the mobile phase during a run? Which is best?
Posted: Fri Dec 05, 2008 2:34 pm
by ym3142
if I understand correctly, you have to be pH 8-9 to get the separation adn wsnt M+.
I guess you may be still able to get Na adduct.
If not, do postcolumn addition
Posted: Fri Dec 05, 2008 2:59 pm
by Uwe Neue
You loose some ionization efficiency, but it still works well. We went to pH 10 for analytes like amitriptyline and were surprised that we still got a good signal. The signal was around 2 to 3 times less than at pH 3, but this is not a big deal if you can get around other problems, such as ion suppression from interferences.