A Novel Use of 3-Methyl-2-Benzothiazolinone Hydrazone Hydrochloride Monohydrate for Kinetic Spectrophotometric Determination of Captopril in Pharmaceutical Formulations

A new, simple and sensitive kinetic spectrophotometric method has been proposed for the determination of captopril (CPT) in pharmaceutical formulations. The method is based on oxidation of 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) by ferric chloride followed by its coupling with the drug to form green-yellow colored product with absorbance maximum at 395nm. The concentration of CPT was calculated using the calibration equation for the rate data and fixed time methods. The linearity range was found to be 0.5–22.5 μg mL-1 for each method. The correlation coefficients were 0.9994 and 0.9971 for rate data and fixed time methods respectively. The proposed methods were applied successfully for the determination of CPT in pharmaceutical formulations. Statistical comparison of the results shows that there is no significant difference between the proposed and official methods.