Copper-modified peanut shell biochar-based electrochemical sensor for the detection of glufosinate ammonium in food and environmental samples.

A novel electrochemical sensing platform was developed using copper-modified and alkali-activated peanut shell biochar (CuPS-OH) for the selective and sensitive detection of glufosinate ammonium (GLA) in food and environmental samples. The sensor operates on the basis of solid-state electrochemical signal amplification from in situ-formed CuCl, which is generated via the reaction between surface Cu species and Cl⁻. GLA specifically binds to copper active sites and competitively suppresses the CuCl signal, enabling quantitative detection. Material characterization confirmed that alkaline treatment significantly improved the conductivity and electroactive surface area of the biochar composite. Under optimized conditions, the sensor exhibited a wide linear range of 0.2-200 µM and a low detection limit of 58 nM. It demonstrated outstanding anti-interference capability, stability, and accuracy in real-sample analyses (grape, river water, and soil), with recoveries ranging from 96.0% to 103.6%. This work offers a feasible and efficient strategy for developing high-performance biochar-based electrochemical sensors applicable to food safety and environmental monitoring.