Rapid on-column analysis of glucosamine and its mutarotation by microchip capillary electrophoresis

A novel electrophoretic microchip method for analyzing α- and β-d-glucosamine and their interconversion in solution is presented. d-Glucosamine is labeled with fluorescamine and analyzed by capillary electrophoresis in under 2 min revealing its pH-dependent mutarotation between the α- and β-anomers. The forward interconversion rates for the labeled sugars, based on an iterative analysis of the plateau heights between the peaks, are 0.72 ± 0.09, 1.3 ± 0.1, and 2.2 ± 0.3 × 10−3 s−1 at pH 8.99, 9.51 and 10.01, respectively. In a separate experiment, the mutarotation of the unlabeled α-d-anomer was followed; the relative intensities of the α- and β-peaks as a function of reaction time at pH 9.51 give a forward rate constant of 0.6 ± 0.1 × 10−3 s−1. These results demonstrate that fast microchip separations, previously exploited for amine, amino acid, and nucleobase analysis, can also be used to analyze amino sugars and their mutarotation.