Oxidation pretreatment by calcium hypochlorite to improve the sensitivity of enzyme inhibition-based detection of organophosphorus pesticides.

Background: Enzyme inhibition-based detection is the most widely used method for rapid detection of organophosphorus pesticides (OPs) in food and agricultural products. However, the accuracy of the method is negatively affected by low inhibitory activities of OPs with PS moiety on acetylcholinesterase.

Results: We demonstrated that oxidation pretreatments with bromine, hydrogen peroxide, or calcium hypochlorite significantly enhanced the enzyme inhibitory activities of these OPs. Especially, calcium hypochlorite (0.05%) pretreatment converted the PS moiety in OPs to PO and produced the most potent and steady inhibitory effect on the enzyme. This, in turn, resulted in a dramatic increase in the sensitivity of enzyme inhibition-based detection of these OPs by as much as 2 to 7 orders of magnitude. Importantly, this enhanced detection of OPs was validated in various vegetable samples.

Conclusion: Our findings provide a solid basis to use calcium hypochlorite pretreatment for the improved detection of OPs by the enzyme inhibition-based method. © 2017 Society of Chemical Industry.