Fluorescent labeling of carbohydrates and analysis by liquid chromatography. Comparison of derivatives using mannosidosis oligosaccharides

To enhance resolution and detectability of carbohydrates by liquid chromatography, two fluorescent labels, introduced into oligosaccharides by reductive amination, were compared by use of standard sugars and a complex, biological sample of D-mannose oligomers obtained from the urine of a mannosidosis patient. Both labels, 2-aminopyridine and 7-amino-1-naphthol, improved the chromatographic efficiency and detection sensitivity. However, reductive amination with the pyridinylamine derivative was incomplete. The Schiff-base intermediates left in the mixtures were only partially resolved by chromatography and complicate the patterns. In contrast, the naphtholamine derivatives were completely reduced and, in addition, possess enhanced fluorescence.