title: Stereoselective dissipation of epoxiconazole in grape (Vitis vinifera cv. Kyoho) and soil under field conditions.
abstract: Stereoselective dissipation of epoxiconazole had been studied in grape and soil during plant growing under field conditions in this paper. A sensitive and rapid chiral method was developed and validated for the determination of epoxiconazole stereoisomers in grape and soil based on liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). Phenomenex Lux Cellulose-1 column was used for enantioseparation with a mixture of acetonitrile/water (90/10, v/v) as mobile phase at flow rate of 0.3 mL min(-1). Fortified recoveries in grape and soil samples ranged from 76.0% to 91.9% and relative standard deviations were less than 11.4% with fortified levels of 0.025-1.0 mg kg(-1). The limits of detection and quantification were 0.005 mg kg(-1) and 0.025 mg kg(-1), respectively, with linear calibration curves extending up to 5.0 mg kg(-1). The field experimental results showed that dissipations of epoxiconazole stereoisomers in grape followed first-order kinetics (R(2)>0.92) and stereoselectivity occurred in 2 h after spraying. The (-)-stereoisomer with half-life of 9.3 d degraded faster than (+)-stereoisomer with that of 13.2 d, and resulted in relative enrichment of (+)-stereoisomer. However, the stereoisomeric dissipations in soil were triphasic ("increase-decrease-steady") with lower dissipation rates, and also occurred with preferential degradation of (-)-stereoisomer under field condition. The results for stereoselective dissipations can be applied for food and environmental assessments of chiral pesticides.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Hongwu
authors.initials: H
authors.lastname: Liang
authors.forename: Jing
authors.initials: J
authors.lastname: Qiu
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhou
authors.forename: Fengmao
authors.initials: F
authors.lastname: Liu
authors.forename: Lihong
authors.initials: L
authors.lastname: Qiu
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004852:Epoxy Compounds / Q000032:analysis / Q000737:chemistry*; D016014:Linear Models; D015203:Reproducibility of Results; D012987:Soil / Q000737:chemistry*; D013237:Stereoisomerism; D014230:Triazoles / Q000032:analysis / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry*
chemical_list: D004852:Epoxy Compounds; D012987:Soil; D014230:Triazoles; C109476:epoxiconazole