Studies On Residual Determination, Degradation Of Tebuconazole In Wheat And It's Environment Behavior In Soil And Safety Evaluation

Tebuconazole is a new type of high performance,low toxicity,broad-spectrum triazole fungicide exploited and produced by Bayer Co.ofGermany. It is effective in the control of many kinds of disease in wheat.In order to evaluate it's safety and lay down the criterion for using safely,at the same time forecast the degree how much it affect the groundwater,the method of tebuconazole residue determination, degradation behaviorin wheat and soil, as well as movement and leaching in soil was studiedand discussed in this dissertation.Residue was detected by GC with ECD detector. The methodprinciple of sample pretreatmeni and the condition of detection wasbelow:Pretreatment of sample: after extracted twice with acetone, add3%NaCL solution and solveni extract twice with petroleum ether(Keepthe proportion of volume among acetone,3%Nacl and for 2:l:l). If thesample is water, add Nacl and a little of acetone first, then solvent extractwith petroleum ether. The water and water-soluble impurities in extractswas removed by Liquid-Liquid partitioning method. The phase lyingabove of extraction was cleanup with acid-washed active charcoal andanhydrous sodium sulfate before concentrated to be ready for detectionGC chromatographic condition. Column: 0.3mm(id)X l.1m glasscolumn; Stationary phase:2%OV---l;Support: Chromosorb. W. AM.DMCS(60--80); Temperature: Detector, 3l0 C, Injector, 3l0 C,0ven: 240aC. Carrier gas: N2 30ml/min. External standard method toqualify and quantify. Minimal determination quantity (MDQ) was 4.79 Xl0-"g. Minimal determination concentration(MDC) of tebucolazole inwheat,seed, soil and water was 3.2 X l0-'mg/kg, 4.8 X l0-'mg/kg, 9.6 Xl 0"mg/kg, 9.56 X l0-'mg/kg respectively.StUdies on residue of tebuconazole showed:Spraying 25%EW oftebucolazole, the dynamic of pesticide accordedwith C=C,e-*, in wheat as well as in soil. The half lives was 5.73days and 5.87 days, respectively. The finally residue was related to theamount and the times that tebuconazoIe had been sprayed, the moreamount or the more times sprayed, the more the residue was. That's to say,there was positive relation between residue and amount as well as timessprayed for.Seed treatment was carried out at the dosage of 0.2--0.4g aitebuconazole/l0kg seed/mu, and sowed. Except for difference offormulation, under the same treatment condition(0.2g ai/l0kgseed/mu),degradation between 2%DS and 2%seed coating fOrmulationwas different though both of them accorded with c==C,e-,, too. Thismeant that the degradation of tebuconazole was related to pesticideformulation.On expression of degradation in the research of seed treatmentfOrmulation, the result of residue was represented with three differentpatterns: the total(absolIJte)residue account in wheat,and two types ofrelating residue----concentration related to dry sample and concentrationrelated to fresh sample. There showed that for all tre8tment the changingrate of concentration,especially in fresh sample, was more quick than thatof the total residue account. That's due to the dilotion of seed groWth.Half lives of 2%DS ranged from 6.02 to 6.62 days fOr the total residueaccount. 5.23 to 5.90 days for concentration in dry sample. 3.64 to 3.79days for fresh samPle. In colltrast, the half lives of 2% seed coatingformulation of tebuconazole,accordingly, was 14.97, 9.54, and 7 days,respectively .however,70 days late when the treated seed had been sowed,residue of tebuconazole wasn't been detected yet neither in the wheattreated with 2%DS nor in the Wheat treated with 2% seed coatingformulation. So they are all safe to the harvesting wheat also.When treat soil by fixing 2%DS. the dynamic of pesticide residueshowed that the half lives of it was 45. l6 days in soil, which was slowerthan that of 25%EW (spraying,5.87 days half lives was)to degradeReason was that there was difference from season, pesticide formulation,mode of using, and position(th...