Voltammetric Quantification of Diclofenac Using a Modified CPE Enriched With TiO2 Nanoparticles and MWCNT

This work describes the development of a voltammetric methodology based on a carbon paste electrode enriched with multiwalled carbon nanotubes and TiO2 nanoparticles, for the electrochemical quantification of diclofenac. All stages of the methodology were optimized by a Box-Behnken experimental design. The electrochemical behavior of diclofenac was studied by cyclic voltammetry. Results showed that the oxidation of diclofenac is favored by the presence of both MWCNT and TiO2 nanostructures since a considerable increase in the anodic peak current is observed when compared to a that obtained with a bare carbon paste electrode. Under the optimal values found and with the appropriate statistical analysis, a LOD of 0.33 ?M, a LOQ of 1.11 ?M, a linear concentration range from 1.1 × 10?6 to 5 × 10?3 M (R2 = 0.9958), and a sensitivity of 0.487 ?A.?M?1 were found. The electrode's response was precise as the reproducibility resulted to be 4.39% (%RSD). Finally, a study of possible interferences was performed, along with the quantification of diclofenac in pharmaceutical samples by the proposed voltammetric methodology. The voltammetric method was validated by comparing the results with those obtained with the UV?vis spectrophotometric method.