Voltammetric study of nimesulide and its differential pulse polarographic determination in pharmaceuticals

Nimesulide, N‐(4‐nitro‐2‐phenoxyphenyl)methanesulfonamide is an antiinflamatory analgesic agent that is both reducible at the mercury electrode and oxidizable at the glassy carbon electrode. Nimesulide in hydroalcoholic solution, presents cathodic response in a wide range of pH (2–12), both, by differential pulse and tast polarography techniques. The obtained results show only one main well‐defined peak or wave in all the pH range studied. This peak (or wave) corresponds to the nitro group reduction in position 4. The voltammetric oxidation shows one well‐resolved signal in all the pH range studied. This anodic signal could be attributed to the methylsulfonamide group oxidation. For analytical purposes, a very well resolved diffusion controlled differential pulse polarographic peak obtained at pH 7 was selected. This peak was used to develop a new method for the determination of nimesulide in pharmaceutical dosage forms. The recovery study (104.8% with a RSD of 1.3%) shows that the method is sufficiently accurate and precise to be applied in the individual tablet assay of commercial samples.