Ready-made chlorpyrifos sensor using an agarose-based gel electrolyte on a reduced graphene oxide/cellulose acetate-modified screen-printed carbon electrode.

Abstract

A ready-made electrochemical sensor has been developed as an innovative platform for detecting nonaqueous chlorpyrifos (CPF), a water-insoluble organophosphate pesticide. Despite its effectiveness, CPF is among the most frequently detected pesticides in food and water and poses severe health risks, including neurological disorders and acute poisoning. As a tool for potentially limiting the harm caused by CPF, this study introduces a CPF sensor designed for simplified sample preparation, enhanced safety, and rapid monitoring in environmental and agricultural samples. The sensor integrates an agarose-based gel electrolyte with a cellulose acetate/reduced graphene oxide-modified screen-printed carbon electrode. The gel electrolyte was prepared by dissolving agarose in a methanol-tetraethylammonium iodide solution and casting it onto the electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) confirmed excellent linearity (R² > 0.999) over 0.05-8.00 mM and 0.10-2.00 mM, respectively, with LoDs of 0.166 mM (CV) and 34.3 μM (0.012 mg/kg, DPV). This allows reliable quantitative analysis and detection below CPF residue limits set by the U.S. EPA and Thai Agricultural Standards. The recoveries for the application of ready-made sensor in environmental and agricultural samples achieved recoveries of 89.8-106.6 % with %RSD below 5 %, demonstrating high feasibility for CPF detection. This sensor enables direct CPF detection in organic solvents without complex preparation or electrochemical expertise. Its agarose gel matrix enhances safety by immobilizing the electrolyte, minimizing leakage, and improving stability, making it suitable for portable use. This ready-made sensor provides a reliable, user-friendly solution for CPF monitoring in agriculture and food safety.