o m o u c Capillary isotachophoresis of some isoquinoline alkaloids*The isotachophoretic behavior of quaternary benzo/c/phenanthridine, protoberberine and aporphine alkaloids in different electrolyte systems is described. The concentration of the leading ion and the pH value of the leading electrolyte affect the relative effective mobilities of the alkaloids. The system of pH 4.7, containing the leading ion K' (0.005 M) counter ion acetate, and the terminating ion p-alanine (0.02 M), has been selected for the quantitative determination ofthe studied alkaloids in model mixtures and plant extracts.