Studies On Residual Behavior Of Triadimenol Enantiomers In Cucumber Plants And Its Photolysis

The separation of 3 chiral pesticides including triadimenol were studied based on the HPLC with chiral stationary phase, and the residual analytical methods of triadimenol enantiomers in plant matrix(leaves, stems and fruits) were founded. Moreover, the residual behaviors of triadimenol enantiomers in the cucumber plants were studied on basis of the above method. It was the first report about the enantioselective behavior of the triadimenol enantiomers in the plant.Enantiomeric separation of 3 chiral pesticides including triadimenol were performed by high performance liquid chromatography with the coating-type amylose-tris [(s)-α-methyphenylcarbamate] as chiral stationary phase(CSP). The chromatographic conditions were optimized by studying the influences of the mobile phase composition including the concentration and type of the alcohol modifier on enantiomers separation. The data indicated that triadimenol, tebucinazole and simeconazole obtained the best resolution with 2% iso-propanol orethanol in mobile phase.The effect of temperature on chiral sepation was investigated and it showed that lower column temperature resulted in a higher separation.The residual analytical methods for triadimenol in cucumber plant matrix were established, and sample was extracted by acetonitrile, cleaned up by Envi-carb-SPE column, then its average recoveries ranged from 79.7% to 90.4% at the fortified levels of 0.1～10.0mg/kg, and the relative standard deviation(RSD) of the method was under 14.1%, the limit of quantitation for enantiomers was 0.025mg/kg.Stereoselective degradation of triadimenol enantiomers in cucumber plants were studied based on field trial and greenhouse experiment. The result demonstrated that there was obvious stereoselectivity of the enantiomers in the cucumber plants. And the dissipation speed of the 4 enantiomers was SS >RR and RS >SR. Moreover, there was a great difference of the stereoselectivity metabolizing intensity in the different tissues of the cucumber plants; however that leaf and cucumber were the most dominating degradation place of the cucumber plants.The photolysis of different enantiomers of triadimenol was also investigated, and which was conducted in water using xenon lamp as the light source. The results showed that the primary degradation of different enantiomers of triadimenol followed apseudo-first-order kinetics in water, and the photolytic rate of triadimenol four enantiomers was the following sequences: RS(+)-triadimenol > SS(-)-triadimenol > RR(+)-triadimenol >SR(-)-triadimenol. The experiment results indicated that there was no transform among the enantioners. From this, the transform between enantiomers should be in a chiral environmental.