Gu Xu, Wang Peng, Liu Donghui, Lv Chunguang, Lu Yuele, Zhou Zhiqiang
Department of Applied Chemistry, China Agricultural University, Beijing, China.
Chirality. 2008 Feb;20(2):125-9. doi: 10.1002/chir.20504.
The stereoselective degradation of the racemic benalaxyl in vegetables such as tomato, tobacco, sugar beet, capsicum, and the soil has been investigated. The two enantiomers of benalaxyl in the matrix were extracted by organic solvent and determined by validated chiral high-performance liquid chromatography with a cellulose-tris-(3, 5-dimethylphenylcarbamate)-based chiral column. Rac-benalaxyl was fortified into the soil and foliar applied to vegetables. The assay method was linear over a range of concentrations (0.5-50 microg ml(-1)) and the mean recoveries in all the samples were more than 70% for the two enantiomers. The limit of detection for both enantiomers was 0.05 microg g(-1). The results in soil showed that R-(-)-enantiomer dissipated faster than S-(+)-enantiomer and the stereoselectivity might be caused by microorganisms. In tomato, tobacco, sugar, beet, and capsicum plants, there was significantly stereoselective metabolism. The preferential absorption and degradation of S-(+)-enantiomer resulted an enrichment of the R-(-)-enantiomer residue in all the vegetables.
已对消旋苯霜灵在番茄、烟草、甜菜、辣椒等蔬菜以及土壤中的立体选择性降解进行了研究。通过有机溶剂提取基质中苯霜灵的两种对映体，并采用基于纤维素-三-(3,5-二甲基苯基氨基甲酸酯)的手性柱，经验证的手性高效液相色谱法进行测定。将消旋苯霜灵添加到土壤中并叶面喷施于蔬菜上。该分析方法在一系列浓度范围（0.5 - 50 μg ml⁻¹）内呈线性，两种对映体在所有样品中的平均回收率均超过70%。两种对映体的检测限均为0.05 μg g⁻¹。土壤中的结果表明，R-(-)-对映体比S-(+)-对映体消散得更快，这种立体选择性可能是由微生物引起的。在番茄、烟草、甜菜和辣椒植株中，存在显著的立体选择性代谢。S-(+)-对映体的优先吸收和降解导致所有蔬菜中R-(-)-对映体残留量增加。
