Electrooxidation and determination of some non-steroidal anti-inflammatory drugs on nanoparticles of Ni-curcumin-complex-modified electrode

The electrooxidation of several non-steroidal anti-inflammatory drugs (indomethacin, mefenamic acid, and diclofenac) was investigated on nanoparticles of Ni-curcumin-complex-modified glassy carbon (n-GC) electrode in alkaline solution. Surfaces studies were performed by scanning electron micrographs and atomic force microscopy. The oxidation process and its kinetics were studied using cyclic voltammetry and chronoamperometry techniques and also pseudo-steady-state polarization measurements. Voltammetric studies indicated that, in the presence of drugs, the anodic peak current of low-valence nickel species increases, followed by a decrease in the corresponding cathodic current. This pattern indicates that drugs were oxidized on the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Ni(III)-active sites and their subsequent consumption by drugs was proposed. The rate constants of the catalytic oxidation of drugs and the electron-transfer coefficient are reported. A sensitive, simple, and time-saving amperometric procedure was developed for the analysis of these drugs in bulk form and for the direct assay of tablets, using the n-GC electrode.