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

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• 作者：Beibei Gao ; Qing Zhang ; Mingming Tian…
• 关键词：Isofenphos ; methyl ; HPLC ; Enantioselective determination ; Absolute configuration ; Chiral separation mechanism ; Stereoselective degradation
• 刊名：Analytical and Bioanalytical Chemistry
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：408
• 期：24
• 页码：6719-6727
• 全文大小：879 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Analytical Chemistry
  Food Science
  Inorganic Chemistry
  Physical Chemistry
  Monitoring, Environmental Analysis and Environmental Ecotoxicology
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1618-2650
• 卷排序：408

文摘

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).