Determination of hydrocortisone 21-hemisuccinate, oxytetracycline and nystatin in pharmaceutical preparations by capillary zone electrophoresis

A capillary zone electrophoresis method is presented to separate hydrocortisone 21-hemisuccinate, oxytetracycline HCl and nystatin by using a fused-silica capillary (57 cm x 75 mum I.D.). The separation was carried out at 30 kV and 25degreesC in a 10 mM phosphate buffer adjusted to pH = 11 as electrolyte. Under these conditions, the run time was 4 min and the limits of quantification were about 2 mg/L for every component. The new method was applied to two pharmaceutical preparations and the results provided recoveries close to 100 %. These results compared well with a reference HPLC method.