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ObjectiveOrganophosphorus (OP) pesticides are considered hazardous substances because of their high toxicity to nontarget species and their persistence in the environment and agricultural products. Therefore, it is important to develop a rapid, sensitive, and economical method for detecting OP pesticides and their residues in food and the environment.MethodsA broad, selective monoclonal antibody (MAb) for organophosphorus pesticides was produced. Based on the MAb, an enzyme linked immunosorbent assay (ELISA) and an immunochromatography assay (ICA) for detecting OP pesticides in different agricultural products were developed using a binding inhibition format on microtiter plates and a membrane strip, respectively.ResultsUnder the optimized conditions, the IC50 values of the ELISA ranged from 3.7 to 162.2 ng mL–1 for the 8 OP pesticides. The matrix interferences of Apple, Chinese cabbage, and greengrocery were removed by 40-fold dilution, the recoveries from spiked samples ranged from 79.1% to 118.1%. The IC50 values of ICA for the 8 OP pesticides ranged from 11.8 to 470.4 ng mL−1. The matrix interference was removed from the Chinese cabbage and Apple samples with 5-fold dilution, and the interference was removed from the greengrocery samples with 20-fold dilution. The recoveries from the spiked samples ranged between 70.6 and 131.9%. The established ELISA and ICA were specific selectivity for the 8 OP pesticides.ConclusionsThe established ELISA is a sensitive screening method for the detection of OP pesticides, but the ELISA detection method depends on a laboratory platform and requires a relative long assay time and several steps operation. The established ICA is very useful as a screening method for the quantitative, semi-quantitative or qualitative detection of OP pesticides in agricultural products, and it has advantages over ELISA methods with regard to factors such as the testing procedure, testing time, and matrix interferences, among others.

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The degradation dynamics and dietary risk assessments of thiamethoxam and thiacloprid during Lonicera japonica planting, drying, and tea brewing processes were systematically investigated using high-performance liquid chromatography. The half-lives of thiamethoxam and thiacloprid were 1.0-4.1 d in the honeysuckle flowers and leaves, with degradation rate constants k ranging from -0.169 to -0.696. The safety interval time was 7 d. The sun- and oven-drying (70 °C) percent digestions were 59.4-81.0% for the residues, which were higher than the shade- and oven-drying percentages at lower temperatures (30, 40, 50, and 60 °C, which ranged from 37.7% to 57.0%). The percent transfers of thiamethoxam and thiacloprid were 0-48.4% and 0-25.2%, respectively, for the different tea brewing conditions. On the basis of the results of this study, abiding by the safety interval time is important, and using reasonable drying methods and tea brewing conditions can reduce the transfer of thiamethoxam and thiacloprid to humans.

BACKGROUND: Fungicides are often applied to pears before they are kept in storage facilities. The scientific application of pesticides can reduce unnecessary exposure, which in turn could benefit both humans and the environment. RESULTS: We investigated dissipation behavior and residue distribution, and conducted risk assessments for prochloraz, pyraclostrobin, and tebuconazole in pears stored under different conditions using ultra-performance liquid chromatography (UPLC). The recoveries of the three fungicides ranged from 76.5% to 114.5%, and the coefficients of variation were 1.0%-8.5%. The half-life (t 1/2 ) ranges for degradation of the three fungicides in Dangshan Su pear peel were 8.8-13.9 days after storage at 25°C and 99.0-346.6 days after storage at 2°C. Among the three fungicides, tebuconazole had the lowest residue concentration in pear pulp (maximum of 0.226 mg·kg −1 ) and the longest half-life (≥ 231.0 days). Accordingly, among these fungicides, tebuconazole is the most suitable for the preservation of Dangshan Su pears during storage. Finally, we analyzed samples of six pear varieties from markets in China and found that the residue concentrations of the three fungicides in pear pulp and fruit met Chinese standards.CONCLUSION: The results provide a scientific basis for rationalizing the use of prochloraz, pyraclostrobin, and tebuconazole, and improving the safety of pears for eating.

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A homogeneous fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody was successfully developed and applied in the determination of clothianidin in agricultural samples. Three fluorescein-labeled clothianidin tracers containing different bridge lengths (2-, 4-and 6-carbon bridges) were synthesized and employed to investigate the effect of tracer structures on the FPIA. Under optimal conditions, the fluoresceinthiocarbamyl hexamethylenediamine-labeled clothianidin conjugate (HMDFlabeled clothianidin), which contains a 6-carbon bridge, performed most sensitively in the FPIA for detecting clothianidin, and the detection was achieved by one step in 12 min with a limit of detection of 5.53 ng mL À1 and an IC 50 of 0.0873 mg mL À1 . There were no obvious cross-reactivities of the antibodies with the analogues except for dinotefuran. Recoveries, measured in spiked water, soil, rice, apple, and cabbage samples, ranged from 78.7% to 108.2% with relative standard deviations less than 12.9%. Furthermore, the FPIA for authentic samples showed reliability and high correlations with ELISA of 0.9845 and HPLC of 0.9653. The developed FPIA demonstrated high sensitivity and accuracy, and could be ideally suitable for rapid, simple, and high-throughput screening for clothianidin contamination in agricultural samples.