Voltammetric Quantification of Diclofenac Using a Modified CPE Enriched With TiO₂Nanoparticles and MWCNT

Abstract

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 μM, a LOQ of 1.11 μM, a linear concentration range from 1.1 × 10−6 to 5 × 10−3 M (R2 = 0.9958), and a sensitivity of 0.487 μA.μM−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.

Development of a Voltammetric Methodology Based on an Artificial Neural Network for the Quantification of Sodium Diclofenac in Pharmaceutical Samples

“…modify the surface of the electrode, however in a previous study by the authors 33 it was shown that, with the proposed electrode, there is no significant effect on the diclofenac signal. Finally, the values of the MSE were calculated using Eq.…”

“…Even when the interference effect of caffeine is not evident since its anodic peak appears at higher potentials than that of diclofenac (Fig. 1, 1.37 V), previous studies of the research group 33 demonstrated that caffeine adsorbs in the electrode's surface changing its characteristics and influencing the diclofenac response. This can be observed in Fig.…”

“…Cyclic voltammetry (CV) was performed to 1 mM solutions of sodium diclofenac, paracetamol, pyridoxine, and caffeine using as electrolyte solution a 0.1 M pH 7 phosphates buffer since in a previous study it was found that this pH is optimal for the electrochemical analysis of diclofenac. 33 Subsequently, differential pulse voltammetry (DPV) was performed on a solution containing diclofenac sodium 59.62 μM, paracetamol 1036.35 μM, pyridoxine 211.85 μM and caffeine 92.93 μM in a 0.1 M pH 7 phosphates buffer; these concentrations were selected according to the amount of the chemicals in the commercial drugs.…”

“…Subsequently, the 27 standards were prepared and DPV was performed under the optimal parameters (potential step of 10 mV, a pulse amplitude of 100 mV, a pulse period of 80 ms, and a pulse width of 20 ms) previously reported by the research group using a Box-Behnken design. 33 Samples.-A matrix of samples containing sodium diclofenac and the interferences was designed using a Plackett-Burman factorial design considering four factors. The factorial design yielded a total of 12 experiments, however, two of them were eliminated as they II.…”

Simultaneous Voltammetric Determination of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Using a Modified Carbon Paste Electrode and Chemometrics

“…In recent decades, electrochemical sensors coupled with voltammetric techniques such as Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV), were the most widely used because they present interesting characteristics for the determination of NSAIDs, dopamine, uric acid, ascorbic acid, among others, such as high sensitivity, high selectivity and accuracy, as well as low cost, and shorter analysis time compared to mass spectroscopy and HPLC [ 7 , 17 , 18 ].…”