Discrimination of isomeric oligosaccharides and sequencing of unknowns by post source decay matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The PSD spectra of some isomeric oligosaccharides are investigated in order to study the fragmentation mechanisms. Results show that intense peaks are formed from one or more glycosidic linkage cleavages, while ring fragmentation produces very weak signals. Two analytical applications of post source decay (PSD) to the structural analysis of oligosaccharides are also illustrated: the discrimination of isomeric structures and the identification of a real unknown by combining PSD data with the linkage analysis results.