Studies On Stereoselective Degradation, Enantiomeric Toxicities And Bioactivities Of Flutriafol

As the chiral pesticides being widely applied in agricultural production, their safety issues have drawn people’s increasing attention. Enantiomers of chiral pesticides were not discriminated in traditional chiral analysis. In terms of bioactivity, toxicity and environmental fate, there often exists difference between enantiomers. In order to provide more accurate data on application safety evaluation on flutriafol, this paper conducted some researches concerning stereoselective degradation, toxicity and bioactivity for flutriafol at enantiomeric level. The main results are listed as following:The enantioseparation was performed using Ultra Performance Convergence Chromatography-tandem Mass Spectrometry(namely UPC2-MS/MS). A comparison was made to study the separation efficiency of flutriafol enantiomers on four different chiral columns. Further optimization on chromatographic parameters were investigated, including the composition of mobile phase, its proportion and its flow rate, column temperature, the ABPR pressure, and the flow rate of compensation solvent. The optimal enantioseparation condition was achieved for flutriafol enantiomers on IA-3 column by UPC2-MS/MS.Photolysis stability for flutriafol enantiomers was performed in selected organic solvents and pure water. The results showed that no interconversion between the two enantiomers of flutriafol was observed under photolysis setting condition. The photolysis rates of flutriafol enantiomers varied with different solvents. Both of flutriafol enantiomers were difficult to photolysis, indicating the stable configuration of flutriafol enantiomers.A chiral residue analytical method was developed for flutriafol enantiomers in various matrices(tomato, cucumber, apple, grape and soil). The samples were extracted with acetonitrile, using the QuEChERS methodology in the sample pretreatment procedure. Meanwhile, the effects of different kinds of sorbents on purification performance and recoveries were investigated. The established method exhibited good linearity with R2 ? 0.9990, and the average recoveries ranged from 77.2% to 98.9% with all RSDs below 9.6%. The limit of quantification(LOQ) was calculated at a range of 0.41-1.18μg/kg. The external standards using matrix-matched calibration were applied for quantification analysis of flutriafol enantiomers. The developed method was proven to be suitable for the requirement of residue determination.Enantioselective degradation of flutriafol enantiomers in greenhouse plants(tomato and cucumber) and soil were investigated. Results showed that, both under foliar spraying treatment and root douche treatment,(-)-R-flutriafol was preferentially degraded in tomato, causing the relative enrichment for(+)-S-flutriafol, and there existed relatively significant enantioselectivity for flutriafol enantiomers in tomato. However, no obvious enantioselectivity was observed for flutriafol enantiomers in soil, and in cucumber under both application modes.The acute toxicities towards non-target aquatic model organism D. magna and bioactivity towards target wheat stripe rust were conducted for flutriafol racemate and its two enantiomers. The results showed that, for D. magna, the 48h- EC50 values were 2.87 mg/L, 1.84 mg/L and 8.56 mg/L for rac-flutriafol,(-)-R-flutriafol and(+)-S-flutriafol, respectively. The order of acute toxicities towards D. magna was(-)-R-flutriafol ? rac-flutriafol ?(+)-S-flutriafol, and the higest acute toxicity of(-)-R-flutriafol was 1.56 folds of that in rac-flutriafol and 4.65 folds of that in(+)-S-flutriafol. The order of bioactivities towards wheat stripe rust was(+)-S-flutriafol ?(-)-R-flutriafol ? rac-flutriafol, moreover, all of the three analytes exhibited better fungicidal activity towards wheat stri pe rust.