Spectrophotometric Assay of Prothipendyl through the Determination of Its Sulfoxide

Abstract

A new difference spectrophotometric method for the analysis of prothipendyl hydrochloride in commercial pharmaceutical preparations has been proposed. The method includes oxidation of an aliquot of the drug solution with potassium caroate to form the corresponding sulfoxide (ε278 = (13.69 ±0.01)×103 L mol/cm) and subsequent measurement of the optical density of the solution at 278 nm compared to that of the unoxidized drug solution of equal concentration. The graph of Beer's law for prothipendyl hydrochloride shows that the ΔA values measured at the corresponding wavelength are proportional to the concentration of the drug in the concentration range of 3.2-60 µg/mL. The characteristics of the curve calibration curve of the linear regression equation were as follows: ΔА = (0.0342±0.0006)C + (0.0501±0.025) (where C in μg/mL). The resulting difference in absorbance is independent of the presence of excipients and degradation products in the formulation. A new spectrophotometric technique has been developed and the possibility of quantitative determination of prothipendyl hydrochloride monohydrate in Dominal® tablets of 40 mg has been demonstrated. RSD =1.4% (δ= – 0.42%).