Development of an electrochemical sensor based on Ce3+ and CuO for the determination of amaranth in soft drinks

A novel Ce3+-doped CuO nanocomposite was synthesized in the present study. The proposed modified carbon paste electrode (Ce3+-doped CuO/CPE) was applied to detect amaranth. Cyclic voltammetry and differential pulse voltammetry were employed to evaluate the electrochemical responses of modified electrode. The oxidation signal of Ce3+-doped CuO/CPE in the presence of amaranth was enhanced which could be related to the synergistic effect of cerium and CuO that improved the electrochemical behavior of electrode for oxidation of amaranth. In this study, the surface areas of bare, CuO/CPE and Ce3+-doped CuO/CPE were calculated 0.043, 0.131 and 0.147 cm2, respectively. The presence of Ce3+-doped CuO at the electrode surface, effectively increased electron transfer rate and surface area which improved the sensitivity of electrode for amaranth determination. Using the scan rate, a diffusion-controlled electrochemical process for the amaranth oxidation on Ce3+-doped CuO/CPE was confirmed. The diffusion coefficient of 1.37×10−5 cm2 s−1 for amaranth was calculated based on the chronoamperometry analysis. The response was linearly for amaranth in the range between 0.05 and 240.0 μM and the limit of detection and limit of quantification were calculated to be 10.2 and 30.9 nM, respectively. Based on the results, the present electrode showed suitable stability, reproducibility and repeatability for amaranth detection. In addition, the proposed electrode was employed to detect amaranth in real specimens, the results of which showed successful outputs.