Spectrophotometric Determination Of Captopril Through Charge-Transfer Complexation
Captopril was quantitatively determined using chloranilic acid through charge-transfer complexation. Favourable conditions like time and temperature for the complex formation were determined. The wavelength for maximum absorption of light by the complex was 520 nm. The complex formation was maximum 30 min after mixing the reactants and room temperature was favourable for the complex formation. Captopril and chloranilic acid formed 1:1 complex in a mixture of dioxan:chloroform activated with dimethylsulphoxide. The association constant, molar absorptivity and free energy change for the complex were 0.6971 I/mol, 2.2462x102 l/mol.cm and 8.828 kcal/mol, respectively. Beer-Lambert's law was obeyed in the concentration range of 0.4- 1.4 mg% (w/v) of captopril. This method was employed in the analysis of captopril in dosage forms and the mean percentage recovery was 96.7%.