Indirect Spectrophotometric Determination of Mefenamic Acid using Safranin Dye

Abstract

A simple, accurate, and rapid indirect spectrophotometric method has been developed for the determination of mefenamic acid in its pure form and in pharmaceutical preparations. The method is based on the oxidation of the mefenamic acid by N-bromosuccinimide (NBS) (excess) and estimating the amount of unconsumed NBS by safranin dye in the presence of the acid and the surfactant SDS in the aqueous medium at λmax = 527 nm. Regression analysis of Beer–Lambert's plot proves excellent correlation in the concentration ranges 0.025 – 5 μg mL-1 with a correlation coefficient 0.993. A molar absorptivity, Sandell sensitivity, and limits of detection (LOD) and quantification (LOQ) were calculated to be 2.05×104 L mol-1 cm-1, 0.0117 μg cm-2, 0.254 μg mL-1 and 0.847 μg mL-1, respectively. The possibility of quantitative determination of mefenamic acid in pure form and in pharmaceutical preparations in the form of syrup and capsules with average recoveries 102.57 %, 100.88 %, and 100.57 %, and RSD ≤ 1.69 %, ≤1.42 % and ≤1.89 % also, respectively, are shown.