Aqueous and non-aqueous capillary electrophoresis of polar drugs

Aqueous and non-aqueous capillary electrophoresis (CE) systems were employe d for the separation of basic and acidic polar drugs using capillary zone e lectrophoresis (CZE) and micellar electrokinetic chromatography (MECC) tech niques. This work was performed to determine the differences in selectivity , after chemical adjustment of the media, of the separation of closely rela ted drugs (by measurement of separation efficiency, resolution and detectio n) in aqueous and non-aqueous solvents. Various electrolytes were tested in aqueous and organic solvent media. The best separation in aqueous CZE was obtained in 25 mM phosphate solution at pH 7.3. In aqueous MECC, the best p erformance was obtained in pH 10.5 buffer containing glycine and dodecyl su lfate. Non-aqueous CE separations were performed in electrolyte mixtures co ntaining methanol-acetonitrile, ethanol-acetonitrile and propan-2-ol-aceton itrile (50:49, v/v) modified by ammonium acetate and water-free glacial ace tic acid. Acetone was also used instead of acetonitrile in the separation m edia. In non-aqueous CE systems, the effect of water in the non-aqueous sam ple and as part of the electrolyte solution played a significant role in th e separation of polar anionic drugs.