Indirect Spectrophotometric Determination of Diclofenac and Isoxsuprine Drugs Using N-bromosuccinimide and Malachite Green Dye

Simple, accurate and sensitive indirect spectrophotometric method for assay of diclofenac (Di) and Isoxsuprine (IS) in pure and pharmaceutical formulation has been developed. The method is based on oxidation of (Di) and (IS) by N-bromosuccinimide in acidic medium. The excess of oxidant is determine by reaction with malachite green dye and the absorbance is measured at 615nm. Under the optimized experimental conditions, Beer's law is obeyed in concentration range 0.5-18 , 1-18 µg/ml with molar absorptivity 5.1×104 and 4.6×104 L.mol-1.cm-1 for (Di) and (IS) respectively. The limits of detection (LOD) 0.0314, 0.038 and quantification are 0.0104 , 0.126 µg/ml. with the accuracy (average recovery) 100.80%, 101.20% for above drugs respectively and the precision (RSD) less than 1.5% for both drugs. The proposed method is applied successfully for assay of pharmaceutical formulations.