Rapid analysis of dichlorvos via releasing the phosphate core

Monitoring the residual dichlorvos (O,O-dimethyl-O-2,2-dichlorovinylphosphate, DDVP) in food has received extensive attention owing to its large consumption in agriculture. However, the previous sensing methods are not time-efficient enough due to the long incubation time for enzyme inhibition (tens of minutes to hours) or bottlenecked by the complicated procedures for senor fabrication. Herein, a novel sensing strategy is proposed based on the hydrolysis of DDVP into PO₄^3-. By using alkaline phosphatase for hydrolysis, a certain portion of DDVP was transformed to PO₄^3- within only 8 min. Then, the released PO₄^3- was detected by a fluorescent terbium metal-organic framework (Tb-MOF). The coordination of the naked P-O groups to the metal nodes of the Tb-MOF disturbed the antenna effects of its ligands. Thus, DDVP was quantified by the decrease of the fluorescence of Tb ions. Based on this method, DDVP residues on plum surfaces were collected by swabs and successfully detected. The recovery of DDVP was determined in the range from 105 % to 115 %, demonstrating the quantification accuracy of this method. The detection limit reached 4.7 μM, which was lower than the restricted amount in fruit set by the National Standard of China. The present method provides an efficient and user-friendly way for the detection of DDVP and many other organophosphorus pesticides in food.