Effect of Graphite Exfoliation Way on the Efficiency of Exfoliated Graphene for the Determination of Hydroxychloroquine in Urine and Waste Water

Abstract

Graphene oxide (GO) electrodeposited on graphite electrode has been used as a sensor for the detection of hydroxychloroquine (HCQ). It was synthesized via a simple and low-cost electrochemical approach by exfoliation of graphite pencil core in aqueous solution of Na2SO4 using a direct current (DC) and alternating current (AC), then electrodeposited at the graphite electrode surface by cyclic voltammetry. The electrochemical performance of the DC−GO and AC−GO toward HCQ oxidation was tested. Graphene oxide (GO) and reduced graphene oxide (rGO) were characterized by UV–vis absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the HCQ oxidation mechanism as well as electron transfer and HCQ quantification at the modified electrode AC−rGO@CPE, respectively. Parameters, such as potential range, scan rate, and the number of segments (half cycle) in cyclic voltammetry were optimized for the electrodeposition of GO. The AC−rGO@CPE shows good sensitivity toward HCQ in the range from 4.0 × 10−7 to 4.0 × 10−6 mol l−1. The detection limit was calculated to be 3.2 × 10−8 mol l−1 with an RSD of 3.47%. Furthermore, the modified electrode was successfully used to detect HCQ in human urine and wastewater.