Safety Evaluation Of 20% Deltamethrin & Imidacloprid Suspension Concentrate In Wild Cabbage

The residue and dissipation dynamics of deltamethrin and imidacloprid in wild cabbageunder field experiments in Tianjin, Shandong and Jiangsu were investigated in this study. Themethod for the analysis of deltamethrin and imidacloprid in the wild cabbage was established.The main results were showed as follows:1. Residue analysis method and purification method of deltamethrin and imidaclopridwere established in wild cabbage and soil. The deltamethrin and imidacloprid could beextracted with acetonitrile、acetone and n-hexane, The recoveries of the three extractingreagent are different .The results indicate that acetonitrile is right extracting reagent.2. The test method that deltamethrin was used gas chromatography with electron capturedetector to detect and imidacloprid was used high performance liquid chromatography withdiode array detector to detect was established. At three concentration levels(0.005, 0.05 and0.5 mg·kg-1), recoveries were in the range of 89.45%~97.24%, with a RSD less than 10% fordeltamethrin in wild cabbage. But the average recovery rates of the analytical method forimidacloprid in wild cabbage were between 80.91% and 97.47% at three concentrationlevels(0.01, 0.05 and 1 mg·kg-1), with the coefficient of variation below 4%. The detectionlimit was 4.0×10-9g for deltamethrin and 5.0×10-10g for imidacloprid, and the minimumdetectable concentration was 0.0005 mg·kg-1for deltamethrin and 0.01 mg·kg-1forimidacloprid in wild cabbage. The accuracy,sensitivity, and precision of the test method couldfit in with the requirement of pesticide residue determination.3. It was found that under field conditions, the dissipation half-lives of deltamethrin andimidacloprid in cabbage was 4.5~8.7 d and 5.7~7.1 d, respectively.The half-life ofdeltamethrin and imidacloprid is less than 30 days, so they could be degraded in wild cabbageand soil, easily.5. When the recommended dosage and 1.5 times recommended dosages of 20%deltamethrin & imidacloprid suspension concentrate were sprayed for 3~4 times at an intervalof 7 d, the residue of deltamethrin and imidacloprid in cabbage in 10th day after sprayingwas safety.6. The results showed that it was safe to use 20% deltamethrin & imidacloprid suspensionconcentrate at 1.5 times recommended dosage(2.25 g/20m2), up to spraying four times, twicespraying interval 7 days ,10 days interval by safety assessment.