Oxidimetric determination of captopril using chloramine-T

Two simple, accurate and precise microprocedures for the determination of captopril with chloramine-T as oxidant have been described. In titrimetry, the aqueous drug solution is titrated directly with, chloramine-T in hydrochloric acid medium using indigocarmine as indicator. The spectrophotometric method is based on the oxidation of the drug by a known excess of chloramine-T in walpole buffer medium followed by estimation of unreacted oxidant using a charge-transfer complexation reaction involving metol and sulphanilic acid. The reacted chloramine-T amount corresponds to the drug content. The oxidation reaction used for titrimetry proceeds at ambient temperature (30 +/- 2degreesC) with a stoichiometry of 1:3 (drug:oxidant). The method is applicable in the range 3-15 mg of captopril. The reaction product used for spectophotometric determination shows an absorption maximum at 520 nm. The Beer's law is obeyed over the concentration range, 0-30 mug ml(-1), the molar absorptivity and the Sandell sensitivity of the system being 5,23x10(3) 1 mol(-1) cm(-1) and 41.53 ng cm(-2), respectively. The limits of detection and quantification were found to be 0.95 and 3.15 mug ml(-1), respectively. Both,procedures have been applied successfully to. the determination of captopril in tablets. The results have been statistically evaluated