Spectrophotometric determination of captopril with DTNB reagent in pharmaceutical formulation.

A simple and sensitive spectrophotometeric method has been developed for the determination of captopril in its dosage form. The method is based on the reaction of the drug with DTNB reagent in pH 8 to produce a yellow coloured species measurable at 412 nm. The absorbance-concentration plot is linear over the range 1-10 x 10(-5) M with correlation coefficient of 0.997. The molar absorptivity and minimum delectability were 13553 and 3.2 x 10(-7) respectively. The proposed method was applied successfully for determination of captopril in its tablets form. The mean quantity and recovery were found to be 25.01+/-2% and 100.04+/-2% (each tablet contain 25 mg captopril). Quantification of the same tablets was determined by a standard method such as HPLC. The mean quantity of each tablet was found to be 25.07+/-1.22% by using HPLC method. It was not statistically, significant difference between Ellman's and HPLC method. This proposed method can be successfully applied to the determination of captopril in water and its dosage form and can use instead HPLC.