Simultaneous Determination of Nimesulide and Valdecoxib by Micellar Electrokinetic Capillary Chromatography Method

Abstract

A micellar electrokinetic capillary chromatography (MEKC) method for the analysis of nimesulide and valdecoxib, using celecoxib as internal standard, has been developed and validated. The MEKC method was carried out on a fused silica capillary (50 µm I.D., effective length 56 cm). The background electrolyte consisted of 35 mM borate buffer and 35 mM of anionic detergent SDS (pH 9.75)/acetonitrile (95:5, V/V). The capillary temperature was maintained at 35°C, the applied voltage was 30 kV, and the injection was performed using the pressure mode at 50 mbar for 5 s, with detection at 234 nm using a photodiode array detector. Method validation investigated parameters such as the linearity (r2=0.9999), range, precision, accuracy, robustness, and specificity, giving results within the acceptable range. The detection limit calculated for nimesulide and valdecoxib was 0.25 and 0.86 µg mL−1, respectively, and the quantitation limit evaluated experimentally was 2 µg mL−1 for both the compounds. The proposed method was successfully applied for the quality control analysis of pharmaceutical products and the results compared to the liquid chromatography method, showing non‐significant difference (P>0.05).