Spectrophotometric and Chromatographic Methods for Simultaneous Determination of Aspirin and Omeprazole

This study represents the development of six simple, fast, and accurate spectrophotometric and chromatographic methods for the simultaneous determination of aspirin (ASP) and omeprazole (OPZ). The method I illustrates the application of Vierordt's simultaneous equations method. Method II applies the first derivative spectrophotometry with the zero-crossing technique. In method III, the ratio spectra derivative spectrophotometry was applied, where ASP and OPZ determination was carried out through measurement of the (DD)-D-1 amplitudes at 285.5 and 265 nm, respectively. Method IV is based on the ratio-difference principle through measurement of the peak to trough amplitudes between 275 and 254.5 nm and between 255 and 275 nm for ASP and OPZ determination, respectively. For method V, HPTLC technique was applied using HPTLC plates of silica gel 60 F-254 and a mobile phase composed of chloroform: methanol (93:7, by volume). For Method VI, the HPLC-DAD technique was applied and the chromatographic separation was achieved using C18 column and a mobile phase consisting of 0.05M disodium hydrogen phosphate (pH 3) and acetonitrile (60:40, by volume). Furthermore, the six developed methods were statistically validated following the ICH guidelines and were effectively applied to the simultaneous analysis of the cited drugs in synthetic mixtures and laboratory-made tablets.