Electrocatalysis of epinephrine by TiO2nanoparticles and 2,2′-[1,7-hepthandiylbis(nitriloethylidyne)]-bis-hydroquinone modified carbon paste electrode

Abstract

A carbon paste electrode, modified with 2,2′-[1,7-hepthandiylbis(nitriloethylidyne)]-bis-hydroquinone (HBNBH) and TiO₂ nanoparticles, was developed and used for the determination of epinephrine (EP). It has been found that oxidation of epinephrine at the surface of such electrodes occurs at potentials less positive than at an unmodified carbon paste electrode. The magnitude of the peak current for HBNBH modified TiO₂-nanoparticles CPE (MTNCPE), increased sharply in the presence of EP and was proportional to its concentration. The electrocatalytic oxidation mechanism of epinephrine (EP), at the surface of the (MTNCPE), was studied by the help of cyclic voltammetry (CV), chronoamperometry (CHA), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). A dynamic range of 2.0–1600.0 μM, with a detection limit of 0.4 μM for EP, was obtained using DPV technique (pH = 8.0). Parameters such as the electron transfer coefficient, α, heterogeneous rate constant, k_s and diffusion coefficient, D for oxidation of EP were also determined. The prepared electrode was successfully applied for the determination of EP in real samples.