Simultaneous spectrophotometric determination of benzyl alcohol and diclofenac in pharmaceuticals using methods based on the first derivative of the optical density ratio

Abstract

Two sensitive and accurate spectrophotometric methods are presented for simultaneous quantitative determination of benzyl alcohol and diclofenac in various pharmaceutical forms. The first method makes use of a derivative of the double-divisor-ratio spectrum of optical density. In this case, the linear determination ranges are 30–97 µg/ml for benzyl alcohol and 12–45 µg/ml for diclofenac. In the second method, the analytical signals are measured at wavelengths corresponding to either maxima or minima for both drugs in the spectra of the first derivative of the ratio of optical densities of the sample and the standard solution of one of the drugs. In this case, the linear determination ranges are 32–95 µg/ml for benzyl alcohol and 14–45 µg/ml for diclofenac. Both analytical procedures do not require any separation of the components. The proposed methods were satisfactorily applied to the rapid simultaneous determination of benzyl alcohol and diclofenac in commercial pharmaceutical preparations and semisynthetic pharmaceuticals containing these drugs.