Sequential removal of monosaccharides from the reducing end of oligosaccharides part IV - End-group determination of oligosaccharides: a gas chromatography-mass spectrometry/mass spectrometry method for distinguishing between all D-aldohexoses and D-ketohexoses

A method for end-group determination of oligosaccharides is described, whic h involves conversion of the reducing monosaccharide into a 1-deoxy-1-hydra zinohexitol heptaacetate (aldohexoses) or an epimeric pair of 2-deoxy-2-hyd razinohexitol heptaacetates (2-ketohexoses). Products are linear and unique to each aldohexose or ketohexose. Methods are reported for separation of a ll stereoisomers of the derivatives on single columns by gas chromatography . Gas chromatography-mass spectrometry/mass spectrometry with electron-impa ct ionization enabled the 1-deoxy-1-hydrazinohexitol heptaacetates and 2-de oxy-2-hydrazinohexitol heptaacetates to be independently identified in each others presence. Chemical-ionization mass spectrometry/mass spectrometry p ermitted derivatives to be identified in subpicomolar quantities. The non-a cetylated compounds could also be identified as their hydrochlorides by H-1 NMR spectroscopy. (C) 2000 Elsevier Science Ltd. All rights reserved.