Stereoselective Degradation Behavior Of Chiral Pesticides Cyflumetofen In Environment

In gerenal, the enantiomers of chiral pesticides are different in some biological processes and thus pose enantioselective environmental behavior and ecotoxicity to nontarget biology. Consequently, it is much more useful and meaningful to evaluate chiral pesticides behavior in enantiomer level. In the present study, the enantioselective degradation of chiral fungicide cyflumetofen in agriculture soils and water based on the high-performance liquid chromatography (HPLC) with chiral stationary phases (CSPs) technology were selected to investigate the enantioselective degradation of cyflumetofen in soil and water.In this research, the method for determination of cyflumetofen was first indentified. Agilent1260HPLC with AD-H chiral column was used. Hexane and isopropanol97:3(v:v) were the mobile phase with flow rate of0.8mL/min, diode array detector wavelength was234nm. The samples were extracted with20mL ethyl acetate by ultrasonic. This method devoted to the quantitive anlysis of cyflumetofen in soil and water.The degradation rate and structure stability of cyflumetofen in6kinds of commonly used solvents was studied in this experiment. Results show that the half-lives were more than120days when cyflumetofen were stored in hexane, isopropyl alcohol, acetone and dichloromethane,9days and28days in methanol and ethanol, respectively. In this six solvents, the enantiomer fraction was0.49～0.51which closed to0.5, that means the enantiomers have no significant difference.(The changes of enantiomer fraction values were compared to analyse the enantioselective degradation behaviors of two enantiomers)Cyflumetofen was added in ground water, rivers, lakes and sterile water for making clearly what the degradation difference in different water. After water cultured for7days, the degradation rate of cyflumetofen were greater than90%and the half-lives in all waters samples were0.9-2.2days, the cyflumetofen degraded rapidly in the water, no significant difference in enantiomer degradation, configuration remained stable.In order to investigate the degradation behavior in different pH soils, cyflumetofen was added in seven different incubation soils. With the view of confirming the reasons of cyflumetofen degradation, the soil were unsterilized and added glusose. Results indicated that the degradation of enantiomers in the test soils during incubation period generally complied with the first-order kinetics(resolution equation is expressed as:Ct=Coe-kt). In different pH soils or incubation conditions, the results revealed that thedissipation rates of cyflumetofen in soils were different, the orders were alkali soil>normal soil>acid soil. By adding glucose to inrich the organic matter in soil, the speed of degradation was faster, It could be proved that the dissipation rates of cyflumetofen isomers were greatly influenced by pH and microorganism value. The single enantiomer was incubate into different soils and the results proved the two enantiomers degradation rate showing no difference.