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A method was developed for the quantative determination of 15 high-risk pesticide and adjuvant (acephate, methomyl, thiamethoxam, thiabendazole, acetamiprid,simazine, pyrimethanil, fludioxonil, boscalid, methoxyfenozide, myclobutanil, fenhexamid, tetraconazole, piperonyl butoxide, chlorpyrifos) residues by SPE-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). The samples were homogenized, extracted with acetonitrile, and cleaned-up by amino solid phase extraction column. The separation was performed on a Shimadu Shim-pack XR-ODS column (75 mm × 2.0 mm, 1.6 μm). The compounds were identified by MS/MS and multiple reaction monitoring (MRM) mode, and quantified by external standard method. The linearities of 15 pesticides and adjuvants were in the concentration range of 0.001-0.5 mg/L, with the correlation coeffecients higher than 0.999 5. At the fortified levels from 0.005 mg/kg to 0.5 mg/kg in pear, grape and apple, the average recoveries of all 15 pesticides and adjuvants ranged from 80% to 115% with the relative standard deviations varied from 5.5% to 16%. The limits of quantification (LOQs) of the analytes were ranged from 0.005 to 0.01 mg/kg. This method is simple, rapid, accutate and therefore, suitable for the confirmation and quantification of the 15 pesticides and adjuvants in fruits. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the dissipation dynamics, residue levels and the dietary intake risk of dithianon and pyraclostrobin in the jujube. Dithianon and pyraclostrobin in the jujube were determined by high performance liquid chromatography with ultraviolet detector. The samples were extracted by acetonitrile, and cleaned up by the florisil column. The dietary intake risk for different groups was estimated with %ADI and %ARfD. At the fortified level of 0.1 to 0.5 mg/kg, the recoveries of dithianon and pyraclostrobin ranged from 76% to 112% with the relative standard deviations of 1.1% to 9.6%. The limit of quantification (LOQ) of this method was 0.1 mg/kg. Dissipation dynamic of dithianon and pyraclostrobin in the jujube fitted the fist-order kinetics equation, with half-lives from 1.5 to 2.5 days and from 12.4 to 18.4 days, respectively. The terminal residues of dithianon and pyraclostrobin were from <0.10 mg/kg to 3.83 mg/kg and from <0.10 mg/kg to 3.07 mg/kg, respectively. The dietary intake risk assessment for the different groups of people shows that the acute dietary intake risk of pyraclostrobin was unacceptable for the children of 2-6 years old at the 7th day after the last application. The dietary intake risk was acceptable in all the other conditions. The security interval of 16% pyraclostrobin·dithianon water dispersible granules was 14 days, when sprayed for 3 times at the dose of 2.67 g/kg for the prevention of anthrax, and the dietary intake of various groups with less risk during the harvest season. [ABSTRACT FROM AUTHOR]