DETERMINATION OF PHARMACEUTICALS AND RELATED IMPURITIES BY CAPILLARY ELECTROPHORESIS

In the first part of this work, the use of capillary electrophoresis ( CE) for the separation of two groups of pharmaceuticals, namely a meta bolite of tamoxifen and a basic drug substance, DS1, was investigated. The effects of pH and types of modifiers, e.g. surfactant, bile salt, gamma-cyclodextrin and hydroxypropyl-beta-cyclodextrin on selectivity , separation and peak shape were studied: Besides achieving complete s eparation of the compounds, the CE system was capable of providing sep aration with significant improvements in overall peak shape of the com pounds compared with HPLC. In the case of the basic drug substance DS1 , validation of the CE system developed in terms of linearity, selecti vity, sensitivity and reproducibility was satisfactorily performed. At the same time, a study of the sample solvent matrix effects on the se paration of this group of compounds was examined. The system was succe ssfully applied to the analysis of laboratory-synthesized samples. Goo d correlation was observed between CE and HPLC, although higher effici ency and faster speed of separation were obtained using the CE system developed. For the tamoxifen metabolite, special emphasis was placed o n the use of CE for the separation of the pair of isomers. This was re adily achieved through the introduction of gamma-cyclodextrin in the e lectrolyte. Resolution of at least 1.5 was obtained for the isomers us ing the CE method.