Development of a quantum dot-labelled biomimetic fluorescence immunoassay for the simultaneous determination of three organophosphorus pesticide residues in agricultural products

In this study, we used 2-(diethexyphosphoryl)acetic acid as a common template molecule and Fe3O4@SiO2 as support material to prepare a superparamagnetic core/shell molecular imprinting polymer (MIP), Fe3O4@SiO2@MIP, which has multiple recognition sites and increased adsorption capacity. Then, a biomimetic fluorescence immunoassay method was developed for the simultaneous determination of methyl parathion, chlorpyrifos, and trichlorfon using the Fe3O4@SiO2@MIP as biomimetic antibody and quantum dots as label. The factors that influenced the performance of this method were optimized. Under optimal conditions the limits of detection of the method were 0.21 +/- 0.021, 0.44 +/- 0.069 and 0.32 +/- 0.033 mu g/L for methyl parathion, chlorpyrifos, and trichlorfon, respectively. To evaluate the accuracy of the method, apple and orange samples spiked with methyl parathion, chlorpyrifos, and trichlorfon were analysed, and the recoveries ranged from 73.1% to 119.3%. Finally, this method was applied to detect three pesticides in pear, carrot, kiwifruit, and banana samples, and the results indicated a good correlation with those obtained from gas chromatography method.