Jarman Jessica L, Jones W Jack, Howell Lorrie A, Garrison A Wayne
Ecosystems Research Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, 960 College Station Road, Athens, Georgia 30605, USA.
J Agric Food Chem. 2005 Aug 10;53(16):6175-82. doi: 10.1021/jf040315o.
The enantiomers of five chiral pesticides of environmental interest, metalaxyl, imazaquin, fonofos (dyfonate), ruelene (cruformate), and dichlorprop, were separated analytically using capillary electrophoresis (CE) with cyclodextrin chiral selectors. For metalaxyl, imazaquin, and fonofos, aqueous slurries of soil samples from two sites in Georgia and one in Ohio were spiked with the racemate of each pesticide at 50-60 mg/L of aqueous phase of the slurry, and CE analyses were performed at various time intervals to determine enantiomer fractions (EF). Metalaxyl underwent enantioselective transformation; in one soil, the half-life of the target active R-(+)-enantiomer was 17 days while that for the S-(-)-enantiomer was 69 days. Transformation occurred more slowly in the other two soils but was still selective for the R-(+)-enantiomer. Imazaquin and fonofos exhibited nonselective enantiomer loss over their 3 months of incubation time; this could have been due to abiotic or nonselective microbial reactions. Ruelene and dichlorprop were transformed selectively in a variety of soils in a previously reported study (7) that showed the influence of environmental changes on the transformation of chiral pollutants in soils; analytical methods used in that study are reported here to further illustrate the application of CE. CE is shown to be a simple, efficient, and inexpensive way to follow the transformation of chiral pesticides in laboratory microcosms where concentrations can be made high enough (25-50 mg/L initial racemate concentration) for detection of residual parent enantiomers during most of the process.
使用带有环糊精手性选择剂的毛细管电泳（CE）对五种具有环境意义的手性农药甲霜灵、咪唑喹啉酸、地虫硫磷（地虫磷）、杀螟腈（巴丹）和二氯丙酸的对映体进行了分析分离。对于甲霜灵、咪唑喹啉酸和地虫硫磷，将来自佐治亚州两个地点和俄亥俄州一个地点的土壤样品的水悬浮液，以50 - 60 mg/L的浆液水相外消旋体添加每种农药，并在不同时间间隔进行CE分析以确定对映体分数（EF）。甲霜灵发生对映体选择性转化；在一种土壤中，目标活性R-(+)-对映体的半衰期为17天，而S-(-)-对映体的半衰期为69天。在其他两种土壤中转化发生得较慢，但对R-(+)-对映体仍具有选择性。咪唑喹啉酸和地虫硫磷在其3个月的培养时间内表现出非选择性对映体损失；这可能是由于非生物或非选择性微生物反应。在先前报道的一项研究（7）中，杀螟腈和二氯丙酸在多种土壤中被选择性转化，该研究表明环境变化对土壤中手性污染物转化的影响；此处报告了该研究中使用的分析方法，以进一步说明CE的应用。CE被证明是一种简单、高效且廉价的方法，可用于跟踪实验室微观世界中手性农药的转化，在该微观世界中浓度可以足够高（初始外消旋体浓度为25 - 50 mg/L），以便在大多数过程中检测残留的母体对映体。
