Gao Beibei, Zhang Qing, Tian Mingming, Zhang Zhaoxian, Wang Minghua
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.
Anal Bioanal Chem. 2016 Sep;408(24):6719-27. doi: 10.1007/s00216-016-9790-7. Epub 2016 Jul 23.
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.
建立了一种利用高效液相色谱-紫外检测同时测定蔬菜、水果和土壤中手性农药甲基异柳磷对映体的对映选择性方法。采用纤维素-三（4-甲基苯甲酸酯）手性固定相（CSP）（Lux Cellulose-3）通过反相液相色谱实现了完全对映体分离。还研究了不同流动相组成、温度和流速对对映体分离的影响。实验和计算的电子圆二色光谱表明，第一个峰是（S）-（+）-甲基异柳磷，第二个峰是（R）-（-）-甲基异柳磷。使用氧化铝-A和弗罗里硅土固相萃取（SPE）柱对蔬菜、水果和土壤样品进行净化。两种对映体的平均回收率在83.2%至110.9%之间，日内相对标准偏差（RSD）为3.2%至10.8%，日间RSD为3.6%至10%。在所有基质匹配校准曲线中，两种对映体在0.25至20 mg L⁻¹范围内均具有良好的线性（≥0.9992）。六种基质中两种对映体的检测限在0.008至0.011 mg kg⁻¹范围内，定量限估计在0.027至0.037 mg kg⁻¹范围内。结果表明，该方法是同时测定食品和环境样品中甲基异柳磷对映体的简便可靠方法。甲基异柳磷在小白菜中的立体选择性降解表明，（R）-（-）-甲基异柳磷异构体（半衰期t 1/2 = 2.2天）比（S）-（+）-异构体（t 1/2 = 1.9天）降解得更快。图形摘要：手性农药甲基异柳磷的对映选择性测定和对映选择性降解。
