title: Enantioselective degradation of metalaxyl in grape, tomato, and rice plants.
abstract: Enantioselective biodegradation of chiral pesticide metalaxyl in grape, tomato, and rice plants under field conditions were studied. Metalaxyl enantiomers were completely separated with a resolution (Rs) of 5.01 by high-performance liquid chromatography (HPLC) based on a cellulose tris (3-chloro-4-methyl phenyl carbamate) chiral column (Lux Cellulose-2). Metalaxyl enantiomers from matrixes were extracted by acetonitrile and purged using Cleanert Alumina-A solid phase extraction (SPE). The linearity, recovery, precision, sensitivity, and matrix effect of the method were assessed. The result showed that significant stereoselectivity occurred in grape, tomato, and rice plants. In grape, (+)-S-metalaxyl with a half-life of 5.5 d degraded faster than (-)-R-metalaxyl with that of 6.9 d, and the enantiomer fraction (EF) value reached 0.37 at 21 d. The same enantioselectivity was observed in tomato, and the half-life was 2.2 d for the S-enantiomer and 3.0 d for the R-enantiomer. The EF values decreased from 0.49 of 0 d to 0.26 of 14 d. On the other hand, a preferential degradation of the R-form was found in rice plants, with an EF value of 0.70 at 14 d, and the corresponding half-life was 2.3 d for the R-form and 2.8 d for the S-form.
authors.affiliation: Department of Pesticide Science, College of Plant Protection, Nanjing Agricultural University, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, P.R. China.
authors.forename: Meiyun
authors.initials: M
authors.lastname: Wang
authors.forename: Xiude
authors.initials: X
authors.lastname: Hua
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.forename: Haiyan
authors.initials: H
authors.lastname: Shi
authors.forename: Minghua
authors.initials: M
authors.lastname: Wang
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D001673:Biodegradation, Environmental; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005659:Fungicides, Industrial / Q000737:chemistry / Q000493:pharmacokinetics; D006207:Half-Life; D018551:Solanum lycopersicum / Q000187:drug effects / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D027843:Vitis / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000097:Acetonitriles; D005659:Fungicides, Industrial; C028175:metalaxyl; D000409:Alanine; C032159:acetonitrile
keywords: enantioselective degradation; grape; metalaxyl; rice plant; tomato