Abstract: In this study, a rapid, simple and highly sensitive fluorescence method for the detection of organophosphorus pesticides was developed based on the oxidase-like activity of manganese dioxide nanosheets and the principle of enzymatic inhibition of organophosphorus pesticides. The contents of organophosphorus pesticides in samples was determined by measuring the change in the fluorescence intensity of the reaction system. An acetylcholinesterase (AChE) concentration of 9.375 U/L, a substrate concentration of 10 mmol/L and a reaction time of 11 minutes were found to be the optimal conditions to achieve the best detection performance. The dynamic detection range of paraoxon was 1.56–200 ng/mL, and the limit of detection (LOD) was 0.5 ng/mL (RSN = 3). The recoveries from tap water, cabbage and oat samples spiked with varying concentrations of paraoxon were in the range of 83.4%–105.9%. These results indicated that this method had several remarkable advantages including rapidity, and high sensitivity and accuracy.

Key words: organophosphorus pesticides; acetylcholinesterase; MnO2 nanosheets; fluorescence analysis;