Synthesis of Reduced Graphene Oxide by Ethyl Acetate and Its Utilization in Determining Hydroxychloroquine in Wastewater and Pharmaceutical Samples

Abstract

AbstractAn easy and sensitive sensor made by carbon paste modified with reduced graphene oxide rGO‐CPE was developed for the detection of hydroxychloroquine (HCQ). Graphene oxide GO was reduced using ethyl acetate. Scanning electron microscope and X‐ray diffraction (XRD) were used for the characterization of rGO powder. The reduction of graphene oxide was confirmed by the disappearance of the identical peak of graphite in the XRD pattern. Herein, the modified electrode rGO‐CPE showed stronger electrochemical activity compared to bare CPE. The electrochemical behavior of HCQ was studied by cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. The mechanism of the HCQ oxidation in the surface of rGO‐CPE was found to be controlled by an adsorption process with the transfer of 2 electrons. Furthermore, the standard heterogeneous rate constant (Ks) and the surface concentration of electroactive species (Γ) were calculated and the obtained values are 1.03×10−2 cm s−1 and 1.07×10−10 mol cm−2, respectively. Differential pulse voltammetry was used for HCQ quantification as a result a linear relationship between HCQ concentration and the oxidation peak current was obtained in the range from 1.0×10−7 to 8.0×10−6 mol L−1 and from 8.0×10−6 to 1.0×10−4 mol L−1, with a detection limit (LOD) of 6.29×10−8 mol L−1 and a sensitivity of 6.42 A L mol−1 cm−2. Moreover, the rGO‐CPE was successfully applied for the detection of HCQ in wastewater and pharmaceutical samples.