title: Enantioselective analysis of triazole fungicide myclobutanil in cucumber and soil under different application modes by chiral liquid chromatography/tandem mass spectrometry.
abstract: A sensitive and enantioselective method was developed and validated for the determination of myclobutanil enantiomers by chiral liquid chromatography coupled with tandem mass spectrometry. The separation and determination were performed using reversed-phase chromatography on a Chiralcel OD-RH column, with ACN-water (70/30, v/v) as the mobile phase under isocratic conditions at 0.5 mL/min flow rate. The matrix effect, linearity, precision, accuracy, and stability were evaluated. The proposed method then was successfully applied to the study of enantioselective degradation of rac-myclobutanil in cucumber and soil under different application modes. The results showed that the preferential degradation of (+)-myclobutanil resulted in an enrichment of the (-)-myclobutanil residue in plant and soil. Moreover, in cucumber, the stereoselective intensity of myclobutanil under root douche treatment was stronger than that under foliar spraying treatment, whereas in soil, the intensity was exactly opposite. The probable reasons underlying these enantioselective effects were also discussed. This study highlighted the importance of examining the fate of both enantiomers in the greenhouse system for the correct use of chiral pesticides.
authors.affiliation: Institute of Plant Protection,  Chinese Academy of Agricultural Sciences , Key Laboratory of Pesticide Chemistry and Application, Ministry of Agriculture, Beijing 100193, China.
authors.forename: Fengshou
authors.initials: F
authors.lastname: Dong
authors.forename: Li
authors.initials: L
authors.lastname: Cheng
authors.forename: Xingang
authors.initials: X
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Yuanbo
authors.initials: Y
authors.lastname: Li
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Kong
authors.forename: Qiu
authors.initials: Q
authors.lastname: Jian
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D000383:Agriculture / Q000379:methods; D002681:China; D002851:Chromatography, High Pressure Liquid; D018553:Cucumis sativus / Q000737:chemistry*; D005506:Food Contamination; D005638:Fruit / Q000737:chemistry*; D005659:Fungicides, Industrial / Q000032:analysis* / Q000737:chemistry; D009570:Nitriles / Q000032:analysis* / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry; D014230:Triazoles / Q000032:analysis* / Q000737:chemistry
chemical_list: D005659:Fungicides, Industrial; D009570:Nitriles; D012987:Soil; D012989:Soil Pollutants; D014230:Triazoles; C446685:systhane