CONSTANT NEUTRAL LOSS SCANNING FOR THE CHARACTERIZATION OF GLYCEROL PHOSPHATIDYLCHOLINE PHOSPHOLIPIDS

The product-ion spectra of the sodiated molecules of glycerol phosphat idylcholine phospholipids (GPC) were obtained, using fast-atom bombard ment (FAB) as the ionization method, in a tandem mass spectrometer. Th e product-ion spectra of these sodiated molecules of GPCs were found t o differ significantly from those of the protonated GPC molecules. Thi s difference is due to the absence of the ion of m/z 184 (protonated-p hosphocholine moiety) and to the presence of an ion resulting from the loss of trimethylamine (m = 59 Da) from the polar head group, which i s the dominant fragmentation. This characteristic neutral loss provide s a means of identification of this class of phospholipids and of diff erentiation from other phospholipid classes in complex mixtures by per forming a constant-neutral-loss scan of 59. (J Am Soc Mass Spectrom 19 98, 9, 1189-1195) (C) 1998 American Society for Mass Spectrometry.