Saccharides and their derivatives are typical polar analytes without a suitable UV-chromophore that are nowadays analyzed by HPLC (high-performance liquid chromatography) under HILIC (hydrophilic interaction liquid chromatography) mode. Usually an evaporative light scattering detector (ELSD) is utilized which, however, gives a nonlinear response. A procedure to overcome the problem of mutarotating (time-varying) analytes recorded with such a nonlinear response detector is described. The procedure was applied for determination of glucosamine in two commercially available pharmaceutical formulations containing the common inorganic ions that the detector gives a response to. Under optimized conditions, both the anomers of glucosamine were separated and could be determined separately. Owing to the short retention time of the analyte (a run time <4 min) and relatively slow kinetics of the anomeric conversion (equilibration time 2.5 h), mutarotation could be monitored and corresponding rate constants calculated.

Department of Chemical Drugs University of Veterinary and Pharmaceutical Sciences Brno Czech Republic

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