Enhancement of the zone electrophoretic separation of 1-phenyl-3-methyl-5-pyrazolone derivatives of aldoses as borate complexes by concerted ion-interaction electrokinetic chromatography with Polybrene

It was confirmed that PMP derivatives of aldopentoses and aldohexoses gave anionic borate complexes in borate buffer and moved to the cathode in an uncoated fused-silica capillary by the combined effects of electroosmosis and electrophoresis. All epimers of each group were completely separated from each other at pH 9.5 because of the difference of the ease of complexation among epimers. Addition of Polybrene to the borate buffer caused reversal of moving direction of PMP derivatives of aldopentoses and aldohexoses due to the ionic association of the resultant borate complexes (ion-interaction electrokinetic chromatography) with Polybrene. The separation of peaks was greatly enhanced when appropriate conditions were used. For example the resolution was prominently increased for all neighboring peaks under the conditions of 50 mM borate and 1% Polybrene concentrations at pH 9.5. The migration order partly changed depending on the conditions employed. This change of resolution can be explained by alteration of the molar fractions of borate complexes, due to exertion of the ionic interaction before attainment of the complexation equilibria. (C) 1998 Elsevier Science B.V.