A copper-based metal-organic framework/reduced graphene oxide-modified electrode for electrochemical detection of paraquat

Abstract

An electrochemical device using copper-based metalorganic franmeworks (MOF) associated with reduced graphene oxide to improve the charge transfer, stability, and adherence of the structures on the surface of the electrodes was developed. The syntheses of these materials were confirmed using scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared and Raman spectroscopy. For the first time, this type of sensor was applied to a systematic study to understand the action mechanism of MOFs and reduced graphene oxide in the electrochemical detection of paraquat pesticide. Under optimized conditions, paraquat was detected in standard solutions by differential pulse voltammetry (- 0.8 to - 0.3 V vs Ag/AgCl), achieving a linear response range between 0.30 and 5.00 μmol L^-1. The limits of detection and quantification were 50.0 nmol L^-1 and 150.0 nmol L^-1, respectively. We assessed the accuracy of the proposed device to determine paraquat in water and human blood serum samples by recovery study, obtaining recovery values ranging from 98 to 104%. Furthermore, the selectivity of the proposed electrode for paraquat detection was evaluated against various interferences, demonstrating their promising application in environmental analysis.

Keywords: Differential pulse voltammetry; Electrochemical detection; Environmental monitoring; Metal-organic framework; Paraquat; Reduced graphene oxide.