Spectrophotometric Estimation of Nimesulide and its Formulations

Abstract

 Four simple and sensitive visible spectrophotometric methods (A–D) have been described for the assay of nimesulide (NMD) either in pure form or in pharmaceutical formulations. Methods A and B are based on the oxidative coupling between the reduced product of NMD (RNMD) and p-N,N-dimethyl phenylenediamine dihydrochloride (DMPD) in presence of chloramine – T (CAT) or 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in presence of ferric chloride (Fe III) to form coloured products with λ_max at 540 nm and 600 nm respectively. Method C is based on the diazotization of RNMD with excess nitrous acid (HNO₂) and estimating the consumed HNO₂ with cresyl fast violet acetate (CFVA). Method D is based on the formation of the coloured charge-transfer complex, when RNMD is treated with metol (p-methyl aminophenol sulphate, PMAP) in presence of potassium dichromate. All variables have been optimized and the reaction sequence is presented. The concentration measurements are reproducible within a relative standard deviation of 1.0%. Recoveries are 98.6–100.2%.