Thiocholine-triggered reaction in personal glucose meters for portable quantitative detection of organophosphorus pesticide

A portable and user-friendly method using personal glucose meters for on-site quantitative detection of organophosphorus pesticide (OP) was developed. The inhibition of organophosphorus compounds on acetylcholinesterase (AChE) leads to reduced yields of thiocholine formed by the enzymatic hydrolysis of acetylthiocholine chloride. Ferricyanide ([Fe(CN)6]3-), the mediator used in glucose test strips for electron transfer to the electrode, can be rapidly reduced to ferrocyanide ([Fe(CN)6]4-) by thiocholine. This reaction enables direct measurement of thiocholine by personal glucose meters in the same way as measuring the glucose in blood, offering an interesting choice to quantify OP. After incubation of AChE for 30 min and enzymatic reaction of 10 min, the yield of thiocholine was measured by a personal glucose meter, achieving detection limit of 5 μg L−1 for paraoxon. The proposed method was successfully applied to the detection in apples and cucumbers, presenting promising potential for on-site OP detection in food samples.