Nonenzymatic Electrochemical Determination of Paraoxon Ethyl in Water and Fruits by Graphene-Based NiFe Bimetallic Phosphosulfide Nanocomposite as a Superior Sensing Layer

A highly sensitive nonenzymatic electrochemical sensor is designed for stripping voltammetric determination of paraoxon ethyl (PE) as a model for nitroaromatic organophosphates (OPs). Graphene-based NiFe bimetallic phosphosulfide nanocomposite is used for the first time as a novel electrocatalytic modifier for enhancing the electrochemical signal of PE. As a consequence of the efficient - stacking interactions between the aromatic structure of OPs and graphene and also due to the strong electrocatalytic properties of the bimetallic phosphosulfide, PE can strongly bind to the surface of modified glassy carbon electrodes and provide a dramatically enhanced voltammetric signal in a nonenzymatic determination method. Maximum square wave voltammetric (SWV) signals were obtained when the adsorption step was completed via 5-min convection at 1000rpm in an analyte solution with the adjusted pH of 6. The SWV signal of PE was highly linear over the range of 12.3-10,000nmolL(-1) and with the detection limit of 3.7nmolL(-1) (S/N=3). The developed sensor shows good reproducibility (RSD=5.2%, N=10). The study offers a promising application for bimetallic phosphosulfide compounds for developing fast, simple, and highly sensitive nonenzymatic determination protocol for nitroaromatic OPs.