Simultaneous Electrochemical Determination of Nimesulide and Thiocolchicoside Using a Newly Electro-Activated Glassy Carbon Electrode

Nimesulide represents a well-established non-steroidal anti-inflammatory drug, while thiocolchicoside is extensively utilized as a muscle relaxant for the treatment of acute musculoskeletal pain and spasms. In this study, a new electrochemically activated glassy carbon electrode was designed and applied for the first time for the simultaneous voltammetric determination of nimesulide and thiocolchicoside. The cyclic voltammetry technique was used for electro-activation, with the activation process optimised in terms of the number and type of cycles, potential ranges, and different electrolytes. The surface properties of the glassy carbon electrode were evaluated using electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy, both before and after activation. A square wave voltammetric method was developed for the simultaneous quantification of nimesulide and thiocolchicoside in Britton-Robinson buffer solution at pH 7.00. The square wave voltammetric peak currents of nimesulide and thiocolchicoside were linear in the range 1.29-59.9 µM and 16.71-158.89 µM, respectively. The method exhibited detection limits of 0.40 µM (nimesulide) and 5.03 µM (thiocolchicoside). Validation, conducted under International Council for Harmonisation guidelines, confirmed sensitivity, linearity, precision, accuracy, recovery, robustness, and ruggedness. Determining the concentrations of nimesulide and thiocolchicoside in combined tablet formulations proved to be an effective use case for the developed method