title: Enantioselectivity in degradation and transformation of quizalofop-ethyl in soils.
abstract: The enantioselective degradation of quizalofop-ethyl and its metabolite quizalofop-acid in two soils, a Wuhan acidic soil and a Baoding alkaline soil, was investigated. The dissipation of quizalofop-ethyl consisted of two phases, a rapidly deceasing first phase that lasted 1 day and a slowly decreasing second phase that extended till the end of the incubation. It is shown that S-quizalofop-ethyl degraded slightly faster than R-quizalofop-ethyl in the two soils. Further incubation of enantiopure enaniomers showed that quizalofop-ethyl was configurationally stable in soil. Quizalofop-acid was produced quickly, and its amount reached a maximum at 1-6 days time and then decreased slowly with half-lives ranging from 11 to 21 days. The results also showed that quizalofop-acid degraded faster in the acidic Wuhan soil than in the alkaline Baoding soil. At last, significant enantiomerization from S-quizalofop-acid to R-quizalofop-acid was observed, and the enantiomerization was fast, resulting in residues enriched with R-quizalofop-acid whatever racemic quizalofop-ethyl or pure enantiomers were initially applied in the soils.
authors.affiliation: College of Science, Hebei University of Science and Technology, Shijiazhuang, Hebei Province, China. lizy666@yahoo.com.cn
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Li
authors.forename: Qiaoling
authors.initials: Q
authors.lastname: Li
authors.forename: Fengning
authors.initials: F
authors.lastname: Cheng
authors.forename: Wenshu
authors.initials: W
authors.lastname: Zhang
authors.forename: Weixiao
authors.initials: W
authors.lastname: Wang
authors.forename: Jingyin
authors.initials: J
authors.lastname: Li
mesh_terms: D006863:Hydrogen-Ion Concentration; D011422:Propionates / Q000737:chemistry* / Q000378:metabolism; D011810:Quinoxalines / Q000737:chemistry* / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D011422:Propionates; D011810:Quinoxalines; D012987:Soil; C064835:quizalofop-ethyl