Differentiation of diastereomeric N-acetylhexosamine monosaccharides usingion trap tandem mass spectrometry

A quadrupole ion trap mass spectrometer equipped with electrospray ionizati on was used to distinguish three diastereomeric monosaccharides, N-acetylgl ucosamine, N-acetylgalactosamine, and N-acetylmannosamine. The saccharides were derivatized to form the metal complex [Co-III(DAP)(2)HexNAc]Cl-3 which , when collisionally activated, produced dramatically different product ion spectra. The product ion spectra generated for the three monosaccharide di astereomers were then used to confirm the stereochemistry of N-acetylhexosa mines from a hydrolyzed oligosaccharide. Finally, the origin of each produc t ion was determined through isotopic labeling studies, and mechanisms were proposed which explain each resulting dissociation.