Study On Degradation Dynamic And Residual Behavior Of Spirotetramat In Soybean And Soil

Spirotetramat is a quaternary acid derivatives and efficient uptake of new insecticide and miticide, is mainly used to control soybean aphids and other sucking insects. As a dual-conductor insecticide in crop, spirotetramat has a unique mechanism of action, which can effectively control existing insecticide resistant pests. There have been few reports about the detection of spirotetramat residue in different samples, and the determination of spirotetramat residue in soybean has not been studied. In the paper, HPLC-UV method was established to detect spirotetramat residue in soybean and soil, and applied on degradation dynamics and final residue analysis of spirotetramat in soybean and soil. The paper is divided into five chapters:preface, the development of spirotetramat residue analysis in soybean and soil, the degradation dynamics and final residue analysis of spirotetramat in soybean, the degradation dynamics and final residue analysis of spirotetramat in soil, summary and discussion.Literature review in foreword mainly includes three aspects, the basic information of spirotetramat, spirotetramat’s field experiment and its residue analysis.Chapter Ⅱ:The development of spirotetramat residue analysis in soybean and soil. Spirotetramat in soybean plants was extracted with acetonitrile by ultrasonic extraction, and purified by an amino solid phase extraction (NH2-SPE) cartridge. UV detection wavelength was 250 nm. The retention time of spirotetramat was approximately 8.140 min. The LOD and LOQ was 0.01 mg/kg and 0.02 mg/kg, respectively. Spirotetramat in soil was extracted with acetonitrile and water by ultrasonic extraction, and purified by liquid-liquid extraction. The mobile phase were acetonitrile and water (40:60, V/V). UV detection wavelength was 201nm. The retention time of spirotetramat was approximately 4.322 min. The LOD and LOQ was 0.015 mg/kg and 0.025 mg/kg, respectively. The recoveries of spirotetramat in soybean and soil were in the range of 82.6%-88.9% and 81.9%～89.8%, with relative standard deviations of 1.4%-2.7% and 0.7%-3.1%, respectively.Chapter III:The degradation dynamics and final residue analysis of spirotetramat in soybean showed:the degradation dynamics of spirotetramat in soybean plants was in accord with the first-order kinetic equation.22.4% spirotetramat SC was sprayed of 1 time at 1.5 times the recommended dose. The original residual deposition of spirotetramat was 0.198 mg/kg. After 5 days, the degradation rate of spirotetramat reached 87.88%, and the half-life was 1.58 days. Final residue analysis of 22.4% spirotetramat SC was carried out once or twice at the recommended dose and 1.5 times the recommended dose, respectively. The spirotetramat residue was determined between 30 or 45 days after the treatment, and the final residues of spirotetramat in soybean plants, green beans and mature soybeans were lower than LOQ of the method.Chapter Ⅳ:The degradation dynamics and final residue analysis of spirotetramat in soil showed that spirotetramat in soil could be quickly degradated, and its degradation dynamics in soil was in accord with the first-order kinetic equation.22.4% spirotetramat SC was sprayed once at the recommended dose. The deposition amount of after 1 day reached the maximum value of 0.218 mg/kg. Spirotetramat degradation rate after 10 days reached 84.85%, and the half-life of spirotetramat in soil was 3.20 days. The final residue analysis of 22.4% spirotetramat SC was performed twice at the recommended dose. The spirotetramat residue was determined at 45,60,90 days after the treatment, and the final residues of spirotetramat in soil samples were lower than LOQ.Chapter Ⅴ:The summary and the innovation of the paper. The differences between the study and other research were evaluated. The drawback of the study was analyzed.