Simultaneous spectrophotometric determination of aspirin, acetaminophen and ascorbic acid in pharmaceutical preparations

Abstract

A simple and rapid first derivative spectrophotometric procedure has been developed for the simultaneous determination of a three component mixture composed of aspirin, acetaminophen and ascorbic acid, without the necessity for the previous separation of any component. In this method, the absorbance ratio technique was used in the first derivative spectra of the compounds. The first two components have a characteristic absorbance in their first derivative spectra (219.3 and 262.5 nm) and they were determined directly by solving the absorbance ratio equation. Ascorbic acid was assayed by subtracting the concentration of aspirin and acetaminophen from the total concentration of the mixture which was calculated from the values belonging to the common isoabsorptive point (221.8 nm) in the first derivative spectrum. The procedure was applied successfully to the analysis of commercial tablets and also compared with an HPLC method.