NEW SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF CAPTOPRIL BULK DRUG AND TABLETS

Three simple, rapid and sensitive methods for the assay of captopril which is an effective alternative to digitalis were developed. These methods are based on the oxidation reaction in aqueous solution of captopril with either ferric chloride or iodine. The indirect quantitation of the product was carried out at 523, 351 and 620 nm for ferro-bipyridyl, residual iodine and residual iodine-starch complex, respectively. All variables were studied to optimize the reaction conditions. Regression analysis of Beer's plot showed good correlation in a general concentration range of 0.25-25-mu-g captopril/ml. No interference was observed from hydrochlorothiazide diuretic which was recently introduced in combination with captopril or other common pharmaceutical adjuvants. The validity of the methods was tested by analysing capoten and capozide tablets. Recoveries were 99.1-102.8%.