SEPARATION OF FLAVONOLS BY CAPILLARY ELECTROPHORESIS - THE EFFECT OF STRUCTURE ON ELECTROPHORETIC MOBILITY

The electrophoretic mobilities of 33 flavonol aglycones and glycosides have been measured to determine the structural factors which influenc e capillary electrophoretic separation. Factors primarily responsible for differences in electrophoretic mobility (EM) in flavonols are: the molecular size; the number and position of the free OH groups on the flavonol skeleton; the number, type and position of attached sugar gro ups; and the presence of ionizable moieties such as sulphate and pheno lic acyl groups. Some structural features of flavonols have a dual eff ect on electrophoretic mobility. Higher levels of glycosylation, for e xample, result in increased molecular size and in a lesser number of i onizable phenolic hydroxyl groups, both of which decrease EM. The data presented provide a basis for predicting relative EMs of flavonols an d their glycosides.