ANION SCREENING FOR DRUGS AND INTERMEDIATES BY CAPILLARY ION ELECTROPHORESIS

A method is described to screen bulk pharmaceuticals and their synthetic intermediates for common anions. Capillary electrophoresis (CE) is a rapid separation technique which operates on the basis of the differential migration of charged and uncharged species in an electric field. Capillary ion electrophoresis utilizes the principles of CE in combination with an osmotic flow modifier and indirect UV detection for the rapid determination and quantification of ions. A Waters Quanta 4000 capillary electrophoresis system, equipped with a 60 cm x 75 mum I.D. fused-silica capillary in conjunction with a patented chromate buffer and osmotic flow modifier is used. The detection limit of the assay is 0.5 mug/ml for most anions. Parameters have been optimized so that all analytes migrate within 5.0 min. A number of optimization experiments for parameters such as loading time, voltage, linearity, precision and detection limit of the system are demonstrated. The effects of the presence of organic solvents in the sample diluents on the migration times of anions are examined. Applications of the technique to pravastatin sodium, taxol and iopiperidol are illustrated. Comparison to ion chromatography, advantages and disadvantages, is discussed.