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

A novel electrophoretic microchip method for analyzing alpha- and beta-D-glucosamine and their interconversion in solution is presented. D-Glucosamine is labeled with fluorescamine and analyzed by capillary electrophoresis in under 2min revealing its pH-dependent mutarotation between the alpha- and beta-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 x 10(-3) s(-1) at pH 8.99, 9.51 and 10.01, respectively. In a separate experiment, the mutarotation of the unlabeled alpha-D-anomer was followed; the relative intensities of the alpha- and beta-peaks as a function of reaction time at pH 9.51 give a forward rate constant of 0.6 +/- 0.1 x 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. (c) 2006 Elsevier B.V. All rights reserved.