Abstract：
In this study, the attention was focused on quizalofop-ethyl, a chiral herbicide whose formulation has recently been marketed as quizalofop-P-ethyl, i.e. the (+)-enantiomer exhibiting herbicidal activity. To verify the real enantiomeric purity of this product as well as to study its environmental fate, the enantioselective separation of the P- and M- enantiomers of quizalofop-ethyl was achieved on Lux Cellulose-2 column (3‑chloro,4-methylphenilcarbamate cellulose) under isocratic conditions in polar organic mode. Once established that the commercial formulation contains ˜ 0.6% (enantiomeric fraction) of M as an impurity, an HPLC-MS/MS method was developed, validated and applied to the analysis of soil, carrots and turnips treated with the herbicide. A simple solid-liquid extraction allowed recoveries greater than 70%; limits of detections of P and M enantiomers were below 5 ng g-1. The analyses of the real samples showed a modification of the enantiomeric fraction of quizalofop-M-ethyl between the commercial formulation (EFM = 0.63 ± 0.03%) and the analysed matrices (EFM = 7.6 ± 0.1% for carrots; EFM = 0% for the other matrices). This outcome highlighted the occurrence of an enantioselective biotic dissipation, responsible for a greater persistency of the distomer in carrots. On the other hand, since screening analyses revealed the occurrence of residues of the metabolite quizalofop-acid with the same EFs as the ester precursor, it was concluded that the hydrolytic conversion was an abiotic process.
摘要：
在这项研究中,注意力集中在quizalofop-乙基上，一种手性除草剂，其配方最近以quizalofop-P-乙基销售，即显示除草活性的(+)-对映体。为了验证该产品的真实对映体纯度以及研究其环境命运，在Lux纤维素-2柱（3-氯，4-甲基苯基氨基甲酸酯纤维素）在极性有机模式下的等度条件下。一旦确定商业制剂含有约0.6%(对映体部分)的M作为杂质，建立了HPLC-MS/MS法,验证并应用于土壤分析，用除草剂处理过的胡萝卜和萝卜。简单的固液萃取使回收率大于70％；P和M对映体的检测限低于5ngg-1。实际样品的分析表明，市售制剂（EFM=0.63±0.03％）和分析的基质（胡萝卜的EFM=7.6±0.1％；其他基质的EFM=0％）之间的quizalofop-M-乙基对映体分数有所改变。这一结果强调了对映选择性生物耗散的发生，负责胡萝卜中食肉动物的更大持久性。另一方面,由于筛选分析显示代谢物quizalofop酸的残留物与酯前体具有相同的EF，结论是水解转化是一个非生物过程。
