End-group determination of oligosaccharides: a gas chromatography–mass spectrometry/mass spectrometry method for distinguishing between all d-aldohexoses and d-ketohexoses Original Research Article

A method for end-group determination of oligosaccharides is described, which involves conversion of the reducing monosaccharide into a 1-deoxy-1-hydrazinohexitol heptaacetate (aldohexoses) or an epimeric pair of 2-deoxy-2-hydrazinohexitol heptaacetates (2-ketohexoses). Products are linear and unique to each aldohexose or ketohexose. Methods are reported for separation of all stereoisomers of the derivatives on single columns by gas chromatography. Gas chromatography–mass spectrometry/mass spectrometry with electron-impact ionization enabled the 1-deoxy-1-hydrazinohexitol heptaacetates and 2-deoxy-2-hydrazinohexitol heptaacetates to be independently identified in each others presence. Chemical-ionization mass spectrometry/mass spectrometry permitted derivatives to be identified in subpicomolar quantities. The non-acetylated compounds could also be identified as their hydrochlorides by 1H NMR spectroscopy.