.30% Poison Fluoride Phosphate Wp On Tobacco Residue Detection Method

A sensitive and exact method was developed for determination of Dufulin residues in tobacco and soil. Tobacco sample were extracted with an ultrasonic bath by the mixture of acetone/petroleum ether, reextracted by the mixture of ethyl acetate/petroleum ether, and then cleaned up by Florisil column; Soil sample were extracted with actone, and then reextracted by the mixture of ethyl acetate/petroleum ether, the extract was evaporated on a vacuum rotary evaporator. The minimum amount of detection was 2×10^-10 g. The detectable limit of concentration was 0.08 mg/kg in tobacco and soil. In tobacco, the average spiked recoveries at levels of 0.08 to 4.00 mg/kg were found to be in the range of 80.0% to 85.3% with the RSD (relative standard deviations) of variation from 2.9% to 8.1%; In soil, the average spiked recoveries at levels of 0.08 to 4.00 mg/kg were found to be in the range of 83.7% to 96.4% with the RSD variation from 1.9% to 17.8%. The result showed that the accuracy and sensitivity of method meet the requirements of pesticide residues analysis.Residual trial of 30% Dufulin wettable powder were conducted in Guiyang of Guizhou province and Qingdao of Shandong province in 2005 and 2006. The result showed that the half-life of Dufulin were 4.1-6.0 days in tobacco and 10.0-12.9 days in soil.Dufulin were treated two and three times and interval of 7 days with the dosages of 500 g.a.i/ha and 1000 g.a.i/ha duing the growing season of tobacco. The terminal residues levels of Dufulin in soil and tobacco were respectively less than 0.31 mg/kg and 0.70 mg/kg after Dufulin being applicated for 21 days. There were positive relationship between residues and amount as well as times, and negative relationship between residues and the days from last application to harvest.