Reductive oxyamination: a method for the qualitative and quantitative analysis of monosaccharides with a new aminooxy reagent using high-performance liquid chromatography with fluorescence detection.

Derivatization of carbohydrates with aminooxy agents to form oximes can be used for qualitative and quantitative analysis of carbohydrates; however, the formation of isomeric products limits its application. A new reductive oxyamination procedure developed for the analysis of monosaccharides with a novel fluorescent O-substituted aminooxy reagent, 4-((aminooxy)methyl)-6-chloro-7-hydroxycoumarin (AOCC), is reported. In this procedure, monosaccharides undergo an oxime formation reaction with AOCC and are then readily reduced with 2-picoline-borane, followed by analysis with high-performance liquid chromatography with fluorescence detection. Good separation of five monosaccharide derivatives was achieved within 40 min with acetonitrile-water-tetrahydrofuran as the mobile phase. The detection limits were on the order of femtomoles. The linear range was 0.2-4000 nM, with a good correlation coefficient (R ≥ 0.9985). Furthermore, the method was applied for analysis of real samples, such as bovine milk powder, without complicated and tedious sample treatment. This reductive oxyamination method circumvents the problem caused by oxime isomers and can be used for the highly sensitive and selective analysis of monosaccharides with high accuracy, providing an effective and promising method for the analysis of carbonyls with aminooxy agents.