title: Enantioselective determination of the chiral pesticide isofenphos-methyl in vegetables, fruits, and soil and its enantioselective degradation in pak choi using HPLC with UV detection.
abstract: An enantioselective method for the simultaneous determination of the chiral pesticide isofenphos-methyl in vegetables, fruits, and soil has been established using high-performance liquid chromatography with UV detection. The complete enantioseparation was conducted by reversed-phase liquid chromatography with a cellulose-tris-(4-methylbenzoate) chiral stationary phase (CSP) (Lux Cellulose-3). The effects of different mobile phase compositions, temperatures, and flow rates on enantioseparation were also investigated. The experimental and calculated electronic circular dichroism spectra indicate that the first peak is (S)-(+)-isofenphos-methyl and the second peak is (R)-(-)-isofenphos-methyl. Alumina-A and Florisil solid-phase extraction (SPE) columns were used to clean up for vegetable, fruit, and soil samples. The mean recoveries of the two enantiomers ranged from 83.2 to 110.9 % with intra-day relative standard deviations (RSDs) from 3.2 to 10.8 % and inter-day RSDs from 3.6 to 10 %. Good linearity (≥0.9992) was obtained for the two enantiomers in all matrix-matched calibration curves in the range of 0.25 to 20 mg L(-1). The limit of detection for two enantiomers in six matrices was in the range of 0.008 to 0.011 mg kg(-1), and the limit of quantification was estimated to range from 0.027 to 0.037 mg kg(-1). The results indicated that this method was a convenient and dependable approach for the simultaneous determination of isofenphos-methyl enantiomers in food and environmental samples. The stereoselective degradation of isofenphos-methyl in pak choi has shown that the (R)-(-)-isofenphos-methyl isomer (half-life t 1/2 = 2.2 days) degraded faster than the (S)-(+)-isomer (t 1/2 = 1.9 days). Graphical Abstract The enantioselective determination and enantioselective degradation of the chiral pesticide isofenphos-methyl.
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, Nanjing, Jiangsu, 210095, China.
authors.forename: Beibei
authors.initials: B
authors.lastname: Gao
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, Nanjing, Jiangsu, 210095, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
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, Nanjing, Jiangsu, 210095, China.
authors.forename: Mingming
authors.initials: M
authors.lastname: Tian
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, Nanjing, Jiangsu, 210095, China.
authors.forename: Zhaoxian
authors.initials: Z
authors.lastname: Zhang
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, Nanjing, Jiangsu, 210095, China. wangmha@njau.edu.cn.
authors.forename: Minghua
authors.initials: M
authors.lastname: Wang
mesh_terms: D001673:Biodegradation, Environmental; D001937:Brassica / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005506:Food Contamination / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D057230:Limit of Detection; D009946:Organothiophosphorus Compounds / Q000032:analysis* / Q000378:metabolism; D010575:Pesticides / Q000032:analysis*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D052616:Solid Phase Extraction / Q000379:methods; D013237:Stereoisomerism; D014675:Vegetables / Q000737:chemistry*
chemical_list: D009946:Organothiophosphorus Compounds; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; C056490:methyl isofenphos
keywords: Absolute configuration; Chiral separation mechanism; Enantioselective determination; HPLC; Isofenphos-methyl; Stereoselective degradation