ABSTRACT
Introduction The development of the desorption technique of fast atom bombardment (FAB) combined with mass spectrometry (MS) has permitted direct analyses of intact complex lipid molecules (1-4). One of the earliest applications of the technique to achieve structural characterization of complex lipids was the analysis of longchain fatty acids by using tandem magnetic sector/high-energy collisionally activated dissociation (CAD) (5,6). These studies led to the discovery of chargeremote fragmentation (CRF), which yields ions informative for locating the position(s) of double bonds within the fatty acyl chains (7-10). The product ions from FAB-generated molecular ions of phospholipids, following CAD with high-or low-energy, could also identify the head groups and the positions of fatty acid substituents on the glycerol backbones. Many of the structurally informative ions generated by CAD are thought to derive from CRF processes (1-10).
