Study On The Residual Detection And Degradation Dynamics Of XDE-175 In Cabbage And Cowpea

In order to provide basis for residual rule of 5.87% XDE-175, analysis methods of 5.87% XDE-175 residue and degradation in cabbage,cowpea and soil and its final residues were studied. The results were shown as follows:1. A detection method of XDE-175 residues in cabbage, cowpea by liquid chromatography was established. The XDE-175could be extracted by (acetonitrile: water=4:1), and purifid by petroleum ether under pH=2, and than extracted with petroleum ether for 3 times under pH=9¹2, collected petroleum ether, after being concentrated by evaporation, Residue analysis method of XDE-175 was established in soil. The XDE-175 could be extracted with methanol: 0.1MNaOH=9:1, and then concentrated by evaporation. Then the concentrated leachates were diluted with mobile phase to volume, then detected in PDA by liquid chromatography of high sensitivity. The accuracy, reappearance and precision of the method well satisfied the essential rules of pesticide residue determination.2. Degradation dynamic of 5.87% XDE-175 in cabbage, cowpea, soil was studied by a two-year field experiment in Tianjin and Anhui province. The rice was treated with pesticide at 85.2 g·mu^-1. Samples of soil, cabbage, and cowpea were analysised at different time, then the degradation procedure was corresponding to the mathematic pattern: C=C0e-kt. The result showed that 5.87% XDE-175 was degraded easily in cabbage, cowpea and soil.3. With sprayed 5.87% XDE-175 on cabbage and soil three or four times at recommended dosage (42.5 g·mu^-1) and one and harf of the recommendation dosage, at the interval of 21 d by a two-year field (2007, 2008) experiment in Tianjin and Anhui province., the results were as follows: the XDE-175 and its metabolite N-demethyl-XDE-175-J and N-formyl-XDE-175-J were not be detected in cabbage and soil after 14d and 21d, 14 d or 21 d interval by safety assessment.4. With sprayed 5.87% XDE-175 on cowpea and soil two or three times at recommended dosage(42.5 g·mu^-1) and one and harf of the recommendation dosage, at the interval of 21d by a two-year field (2007, 2008) experiment in Tianjin and Anhui province., the results were as follows: the XDE-175 and its metabolite N-demethyl-XDE-175-J and N-formyl-XDE-175-J were not be detected in cabbage and soil after 14 d, 14 d interval by safety assessment. 5. According to the search, the U.S. Environmental Protection [EPA] requirements, theXDE-175 residue limited license: Cabbage MRL is 10 mg·kg^-1, cowpea MRL is 0.04 mg / kg. The result showed that the safety interval should be 1 day, and 3 days in cowpea after the use of 5.87% XDE-175 at this recommended dosage.