ELECTROPHORETIC RESOLUTION OF MONOSACCHARIDE ENANTIOMERS IN BORATE OLIGOSACCHARIDE COMPLEXATION MEDIA

Monosaccharide enantiomers have been directly separated by capillary electrophoresis as complexes with borate and linear or cyclic dextrins of the general poly(gly-(1-4)-alpha-D-Glu) structure. Their relative electrophoretic migration and their separation selectivity were mainly influenced by the type and concentration of the chiral additive, the concentration of boric acid, and the chemical nature of a fluorescence-tagging (derivatizing) agent. The analytes were detected by laser-induced fluorescence. All sugar enantiomers were resolved using beta-cyclodextrin as the electrolyte additive. Their migration order could be adjusted by a type of chiral additive, a derivatizing agent, or the surface property (chemical modification) of the separation capillary. Under certain electrolyte conditions, base-line separation of the sugar enantiomers could be completed in times as short as 30 s. The complexation-induced shifts observed in the H-1 NMR and fluorescence spectroscopy experiments were in agreement with the results obtained by capillary electrophoresis. A possible mechanism for the chiral recognition is proposed.