Abstract
A CE method for investigating the chemico-physical characteristics of the active components of low molecular weight in Gastrodia elata Bl. is described. First, the dissociation constants of five active components were determined based on the relation between the effective mobility of the solutes and the buffer pH value. Second, an equation that describes the relation of the migration time and the molecular weight was developed and used to predict the migration order and to calculate the electroosmotic velocity. The results predicted by theory agreed well with that from experiments.