Study on the stereoselective degradation of three triazole fungicides in sediment

The stereoselective degradation behaviors of chiral triazole fungicides (hexaconazole, flutriafol and tebuconazole) in sediment were investigated under laboratory conditions. The enantiomers were completely separated by high-performance liquid chromatography on a cellulose tris(3-chloro-4-methylphenylcarbamate) (Lux Cellulose-2) column. The mean recoveries of hexaconazole, flutriafol and tebuconazole in sediment ranged from 86.7% to 105.9%. The methods were successfully applied for the enantioselective degradation analysis of fungicides in sediment. The results showed that the dissipation of hexaconazole, flutriafol and tebuconazole stereoisomers in sediment followed first-order kinetics (R(2)>0.95). The degradation rate of the enantiomers was different in sediment, and the (-)-enantiomer (t(1/2) was 86 days for hexaconazole, 139 for flutriafol and 136 for tebuconazole) degraded faster than the (+)-enantiomer (t(1/2) was 94 days for hexaconazole, 144 for flutriafol and 151 for tebuconazole) in native condition. The fungicides were degraded slowly, and no significant enantioselective degradation were observed under sterilized conditions. The results may hold promising implications for the environmental and ecological risk assessment of three important chiral triazole fungicides.