[Detecting organophosphorus pesticide in water environment using an enzyme biosensor]

Based on a screen printed carbon electrode which contained a sensitive film prepared by crosslinking acetylcholine esterase (AChE) with glutaraldehyde on the surface of working electrode, an amperometric enzyme biosensor was taken on the determination of organophosphorus (OP) pesticide in water environment. Cyclic voltammetry was applied to assess the coherence of prepared screen printed electrodes. The results show that the variation is less than 10%. The sensor sensitivity was optimized with respect to content of enzyme, crosslinker and substrate. The best sensitivity is obtained using 0.2% of glutaraldehyde, 0.5 mg/mL of AChE and 10 mmol/L of acetylthiocholine chloride (ATChCl). Amperometric I-t curve was conducted to detect the decrease rate of the current after the addition of two kind of OPs (terbufos and parathion), respectively. The detection limit for two kind of OPs are found to be 1 ng/mL with the linear range 1 ng/mL - 10 000 ng/mL. Cyclic voltammetry was conducted to detect parathion on the sensors which immobilized AChE by physical adsorption. The results show that it can achieve a better sensitivity than amperometric I-t curve.