A Smartphone-Based Portable Electrochemical Assay for Organophosphorus Pesticide Detection Based on the Electron Transfer-Promoting Effect of Thiocholine

A straightforward and cost-effective assay has been developed for detecting organophosphorus pesticides (OPs) utilizing a portable electrochemical sensing system integrated with smartphones. Thiocholine (TCh), generated through the catalytic hydrolysis of acetylthiocholine (ATCh) by acetylcholinesterase (AChE), enhances electron transfer between electrodes and the [Fe(CN)₆]^3–/4–. OPs inhibit AChE, reducing TCh output and causing a decrease in the electrochemical signal. Employing methyl parathion detection as a model, this method demonstrates a broad dynamic range (0.05–100 µg/mL) and a low detection limit (17 ng/mL). Furthermore, the strategy exhibits exceptional selectivity and reproducibility, while also confirming the applicability of methyl parathion detection in cabbage samples.