Dynamic Of Spirotetramat Degradation In Tomato Plants And Soil

Spirotetramat is a unique tetramic acid insecticide which has been described as a two-waysystemicity, it can control of a range of sucking insects. There is a lack of investigation on the fate ofspirotetramat in environment, only a few of researches on residue analysis method processed both inChina and abroad. In this dissertation, spirotetramat was investigated as follows: the analytical methodswere established to determine the residue of spirotetramat in soil, water, tomato and tomato leaves;spirotetramat absorbed and transported by tomato plants; the degradation rule of spirotetramat wasstudied on tomato, tomato leaves and soil; degradation of spirotetramat and environmental behavior ofspirotetramat was studied with respect to hydrolysis, photolysis and the degradation of different kinds ofsoil.Spirotetramat in matrix extracted by acetonitrile, and determining by LC-20AT with SPD-20Adetector. The LOQ of spirotetramat was0.05mg/L in water,0.01mg/kg in soil,0.025mg/kg in tomatoand0.02mg/kg in tamato leaves respectively. The recoveries of spirotetramat ranged from86.6to115.0%,110.8%to121.4%,88.0%to98.3%,82.7%to100.9%, with coefficient of variation of2.35%to8.35%,2.37%to10.51%,1.11%to6.64%,2.16%to9.63%in tomato, tomato leaves, different kindsof soil and water of different values of pH. The results shows that the accuracy, precision and sensitivityof the method all meet the requirements for pesticide residue analysis.The tests of absorption and transportation of spirotetramat in tomato plants showed thatspirotetramat can be easily absorbed by the leaves, and transited to the top and bottom leaves. Thehighest level of spirotetramat in top leaves was0.31mg/kg after applying for1d, there was2.44mg/kg inbottom leaves at the same time, much more than top leaves. Spirotetramat can be weakly absorbed byroot and transited to other parts of the plant.Spirotetramat can be easily degraded both in soil and plant. The results of digestion ofspirotetramat in tomato, tomato leaves, and soil showed that the half-lives of spirotetramat are14.25d,12.61d and0.58d respectively.The dissertation states the effect of degradating for photolysis, hydrolysis and micro-biologicaldegradation. Study found that spirotetramat in buffer with high pH and temperature are easily degraded.Comparing with shading samples, we found that light plays a role in the degradation of spirotetramat.After discuss the degradation of spirotetramat in different soils, we concluded that the microorganismaccelerate the degradation of spirotetramat, and the characteristic of soil had a significant effect on thedegradation of spirotetramat in soil.