Establishment of an Enhanced Enzyme Inhibition Assay for Rapid Detection of Organophosphrous Pesticides Residues in Grain

In this study,an enhancer-based enzyme inhibition method was established to achieve rapid detection of organophosphorus pesticide residues in cereals. The extractant,enzyme and enhancer used in the enzyme inhibition method were selected and optimized,by comparing the change of inhibition rate. Finally,butylcholinesterase was used as catalytic enzyme,ethanol selected as extractant,and bromosuccinimide as enhancer. Under these optimized conditions,the standard curves of parathion,phoxim,chlorpyrifos and triazophos were established(R²＞0.98). The IC₅₀ values were 0.01,0.11,0.16 and 0.03 μg/L,respectively,which met the safety residue limits of this kind of pesticides. 200 grain samples(rice,wheat,maize,brown rice,miscellaneous grains)were tested using the improved enzyme inhibition method,in which 13 positive samples were detected,however,due to the specific limitation of the enzyme inhibition method,1 false positive samples and 1 false negative samples were generated. Results of exemplarily performedgas chromatography were well in accordance with measurements obtained by enzyme inhibition,and it was proved that the developed method could be used to detect the organophosphorus pesticide residue in the grain. This study can provide a powerful technical support for China grain quality safety supervision.