Characterization of sodiated glycerol phosphatidylcholine phospholipids bymass spectrometry

Fast atom bombardment mass spectrometry in the positive mode was used for t he characterization of sodiated glycerol phosphatidylcholines. The relative abundance (RA) of the protonated species is similar to the RA of the sodia ted molecular species. The sodiated fragment ion, IM + Na - 59](+), corresp onding to the loss of trimethylamine, and other sodiated fragment ions, wer e also observed. The decomposition of the sodiated molecule is very similar for all the studied glycerol phosphatidylcholines, in which the most abund ant ion corresponds to a neutral loss of 59 Da. Upon collision-induced diss ociation (CID) of the [M + Na](+) ion informative ions are formed by the lo sses of the fatty acids in the sn-l and sn-2 positions. Other major fragmen t ions of the sodiated molecule result from loss of non-sodiated and sodiat ed choline phosphate, [M + Na -183](+), [M + Na - 184](+) and [M + Na - 205 ](+), respectively. The main CID fragmentation pathway of the [M + Na - 59] (+) ion yields the [M + Na - 183](+) ion, also observed in the CID spectra of the [M + Na](+) molecular ion. Other major fragment ions are [M + Na - 2 05](+) and the fragment ion at m/z 147. Collisional activation of [M + Na - 205](+) results in charge site remote fragmentation of both fatty acid alk yl chains. The terminal ions of these series of charge remote fragmentation s result from loss of part of the R-1 or R-2 alkyl chain. Other major infor mative ions correspond to acylium ions. Copyright (C) 2001 John Wiley & Son s, Ltd.