Study of the capillary zone electrophoretic behaviour of selected drugs, and its comparison with other analytical techniques for their formulation assay

Capillary zone electrophoresis (CZE) was used to study the migration behaviour of selected 1,4-benzodiazepines and metabolites over the pH range 2-12, exhibiting the ability to determine pK(a) values using this technique. The selectivity of capillary electrophoresis was then demonstrated for the separation of four benzodiazepines using capillary zone electrophoresis with 20 mM citric acid + 15% methanol, and micellar electrokinetic capillary chromatography with 75 mM sodium dodecyl sulphate in 6 mM sodium tetraborate-12 mM disodium hydrogen phosphate + 5% MeOH, and compared with other topical analytical techniques in terms of retention times, capacity factors and efficiencies. Capillary zone electrophoresis was also applied to the assay of a variety of pharmaceutical formulations which contain 1,4-benzodiazepines, omeprazole and metronidazole, and was compared with alternative analytical techniques such as reversed-phase high-performance liquid chromatography, capillary gas chromatography and automated differential pulse polarography. Limits of detection of CZE and the alternative techniques are also compared for these molecules.