| Pymetrozine, as a new active selective insecticide whose basic structure is a pyridine, is getting more attention from the national market and aboard for its unique effect. This paper purposes on dealing with the trade barrier of pesticide residue limitation, developed a novel and simple method for determination of pymetrozine in broccoli and soil, analyzed the degradation of its residue in the broccoli-field ecosystem and its hormetic effect to the earthworms( Eisenia foetida). The results presented as follows:As the condition of chromatographic column was settled as VP-ODS (150mm×4.6mm), UV detection wavelength was settled as 299nm, the temperature of chromatographic column was settled at 40℃, sample size was settled at 20μL, the fluid speed was settled at 0.6ml/min, the results of the experiment showed that acetonitrile-water was the best mobile phase for HPLC determination of pymetrozine.The results of optimizing research defined that: the temperature of chromatographic column was 20℃, V(acetonitrile):V(water)=85:15, sample size was 10μL, fluid flow was 1mL/min.The retain time of pymetrozine was 3.381min and the standard curve equation was Y=411.4+17382X. The minimum amount of detection was 1.0×10-10g and the detectable limit of concentration was 0.005mg/kg.The recovery of pymetrozine in broccoli were determined from 86.57 to 96.57%, the average recovery were 87.29%,93.60% and 91.57%, respectively, while the CV were 0.78%,1.93% and 3.14%, respectively.The recovery of pymetrozine in soil were determined from 76.17 to 96.11%, the average recovery were 90.08%,84.18% and 87.24%, respectively, while the CV were 9.70%,10.13%and 7.34%, respectively.The results of residual trial of 25% pymetrozine showed that under applied level of, the half-life of pymetrozine in broccoli was 3.5 days and 1.4 days in soil, the safety harvest interval was 21 days.The BMDS tests concluded that BMD & BMDL were 1.6451mg/L and 1.56287mg/L. Using the weight of earthworms as targets to set the hormesis model, the regression curve was f(x)=0.0029+0.0116x-0.0309x2, ZEP was 0.3754mg/L, and the P-Value was 20.01%. |
