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 influence 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 groups; and the presence of ionizable moieties such as sulphate and phenolic acyl groups. Some structural features of flavonols have a dual effect on electrophoretic mobility. Higher levels of glycosylation, for example, result in increased molecular size and in a lesser number of ionizable phenolic hydroxyl groups, both of which decrease EM. The data presented provide a basis for predicting relative EMs of flavonols and their glycosides.