A Difference Spectrophotometric Method for Determination of Alimemazine Based on the Absorbance of its Sulphoxide

Abstract

A new difference spectrophotometric method for the analysis of alimemazine in commercial formulations has been proposed. The method is based on oxidizing the drug with potassium caroate for the formation of corresponding sulfoxide (ε = (4.7 ± 0.06) · 103 L mol-1 cm-1) and measuring the absorbance of the solution at 342 nm using an unoxidized drug of the same concentration as blank. The graph of Beer's law for alimemazine tartrate showed that the ΔA values measured at the corresponding wavelength of maximum absorbance difference are directly proportional to the drug concentration in oxidized solutions in the range 2-30 μg/mL. The characteristics of the calibration curve were A = (b ± Δb) · C - (a ± Δa) = (0.0539 ± 0.0014) · C - 0.017 ± 0.026; LOD = 0.68 μg mL-1; LOQ = 2.07 μg mL-1. The proposed method was successfully applied for the analysis of alimemazine-containing commercial pharmaceutical formulations: Teraligen Valenta tablets 5.0 mg and Theralene 4 %, oral solution. RSD ≤ 1.8 % (δ= – 0.82 % and –1.30 % respectively).