The effect of tamoxifen on the electrochemical behavior of Bi⁺³/Bi on the glassy carbon electrode and its determination via differential pulse anodic stripping voltammetry

The electrochemical behavior of Bi⁺³ ions on the surface of a glassy carbon electrode, in acidic media and in the presence of tamoxifen, was investigated. Cyclic voltammetry, chronoamperometry, differential pulse voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy with energy-disperse X-ray spectroscopy were used to find the probable mechanism contributing to the reduction of the peak height of bismuth oxidation with an increase in the concentration of tamoxifen. The obtained results show a slight interaction between the bismuth species and tamoxifen which co-deposit on the surface of glassy carbon electrode. Therefore, the reduction in the peak height of bismuth oxidation as a function of tamoxifen concentration was used to develop a new differential pulse anodic striping voltammetry method for determination of trace amount of tamoxifen. The effects of experimental parameters on the in situ DPASV of Bi⁺³ ions in the presence of tamoxifen shown the optimal conditions as: 2 mol L^-1 H₂SO₄ (1% v v^-1 MeOH), a deposition potential of -0.5 V, a deposition time of 60 s, and a glassy carbon electrode rotation rate of 300 rpm. The calibration curve was plotted in the range of 0.5 to 6 μg mL^-1 and the limits of detection and quantitation were calculated to be 3.1 x 10^-5 μg mL^-1 and 1.0 x 10^-4 μg mL^-1, respectively. The mean, RSD, and relative bias for 0.5 μg mL^-1 (n=5) were found to be 0.49 μg mL^-1, 0.3% and 2%, respectively. Finally, the proposed method was successfully used for the determination of tamoxifen in serum and pharmaceutical samples. (author)