Capillary electrophoresis for drug analysis and physicochemical characterization

Abstract Capillary electrophoresis comprises of a series of related techniques that employ narrow-bore capillaries to perform high-efficiency separations. These separations are achieved by filling the capillary with an electrolyte solution, usually pH buffered, and applying a high voltage between the two ends of the capillary, which may generate electroosmotic and electrophoretic flows of buffer solution and ionic species, respectively, within the capillary. The simplest technique is capillary zone electrophoresis where drugs are separated according to their charge/size ratio. Thus, it can be applied only to ionic or ionizable drugs with an appropriate control of the buffer pH. Addition of ionic surfactants, microemulsions or liposomes to the buffered mobile phase creates an additional pseudostationary phase which migrates more slowly through the capillary. Neutral drugs can then be separated according to their partition between mobile and pseudostationary phases. This chapter reviews the most important modes and applications of capillary electrophoretic techniques in drug analysis and physicochemical characterization.