fragmentation in ion source
Posted: Wed Mar 14, 2007 8:10 pm
by shangyer
Recently, I try to tune MS (quattro LC) with the synthezied compounds. The problem is that when cone value is low I mainly get sodium adduct, when the cone value is high, I got a lot of fragments. This is just Q1 tuning. I got good {M+H}+ with API 2000 with little fragments. What cause the problem, is it because of Z spray? I use 5mM ammonium acetate as buffer. 50/50 h2o/acn.
Posted: Fri Mar 23, 2007 3:36 am
by james little
We have a Quatro Micro and a 4000 Qtrap. A few compounds form M+Na adducts on the Quattro Micro more than 4000 Qtrap. However, generally I get either M+H ions or M+NH4+ ions at low cone voltage. The M+Na signal tends to increase at higher cone voltages (>50).
For the few compounds that gave primarily M+Na, I tried playing with acid content and every variable I could think of..
However, very little change.
Might look at your tubing and make sure not contaminated with salt from some other work? I guess some sodium could come from your glass reservoirs, but not too likely. We use glass solvent reservoirs all the time.