Electrochemical sensor for simultaneous determination of dopamine and epinephrine based on reduced graphene oxide/TiO2 nanocomposite

Measuring the insignificant amounts of catecholamines in biological samples is of particular importance due to the very important biological role that the human body plays in preventing diseases such as Parkinson s, and many ways to improve sensitivity and the reliability of these measurements has been developed. One of the best practices is the use of electrochemical sensors. Graphene, as a carbon material, has special properties that make it an ideal choice for generating graphene-based composite materials. Graphene properties increase with the combination of nanoscale materials and the formation of unique composites. Today, the presence of nanoparticles in composite materials has unique properties [1-3].In this study, reduced graphene oxide/titanium dioxide nanocomposite (RGO/TiO2) was synthesized by using a chemically method and used for simultaneously determination of dopamine and epinephrine. The morphology and structure of the nanocomposite was characterized by the field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Electrochemical and electrocatalytic behavior of this modified electrode for simultaneous determination of these species were carried out in pH 7.0 PBS, by cyclic voltammetry (CV) and Differential pulse voltammetry (DPV). Under optimum conditions, the calibration curve is plotted for each of the desired compounds. The dopamine shows three linear regions of 5.0-15.0 μM, 15.0-180.0 μM and 180.0-1000.0 μM and. Epinephrine also shows two linear regions from 5.0-20.0 μM and 20.0-1000.0 μM. The detection limit based on (S/N = 3) for simultaneous determination of dopamine and epinephrine was 0.23 μM and 0.18 μM, respectively. The nanocomposite film sensor was successfully used to accurately detect the content of EP in practical samples, and the recoveries for the standards added are 97%–103%.