CHARACTERIZATION OF 1-MONOACYLGLYCERIDES AND 2-MONOACYLGLYCERIDES BY FAST-ATOM-BOMBARDMENT, COLLISION-INDUCED DISSOCIATION AND TANDEM MASS-SPECTROMETRY

Monoacylglycerides containing saturated and monounsaturated acyl chain s have been examined by fast atom bombardment (FAB), collision-induced dissociation (CID) and tandem mass spectrometry. The results show tha t low-energy CID of [M + H](+) ions enables one to differentiate betwe en 1- and 2-monoacylglycerides containing a monounsaturated acyl chain . Low-energy CID of [M + Li](+) ions was found to be superior to that of [M + H](+) ions because a differentiation could be made for the fou r isomeric pairs studied. However, the observed effects could only be noted at a very low collision energy (20 eV). High-energy CID of [M Li](+) and [M + Na](+) ions was found to be more useful than that of [ M + H](+) ions because detailed structural information was obtained;on the fatty acyl chain. In contrast to low-energy CID, no differences b etween 1- and 2-monoacylglycerides could be observed in the high-energ y CID mode.