Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Key Laboratory of Integrated Pest Management in Crops, Ministry of Agriculture, Beijing 100193, People's Republic of China.
Environ Sci Technol. 2012 Mar 6;46(5):2675-83. doi: 10.1021/es203320x. Epub 2012 Feb 16.
Fenbuconazole is a widely used systemic agricultural fungicide of the triazole class with one chiral center. In the present study, the enantioselective degradation of fenbuconazole and its chiral metabolites, RH-9129 and RH-9130, in two soils under aerobic and anaerobic conditions were investigated using a chiral OD-RH column on a reversed-phase liquid chromatography-tandem mass spectrometry system. Under aerobic or anaerobic conditions, the results showed the occurrence of enantioselectivity with (-)-fenbuconazole preferentially degraded in both soils. Further enantioselective analysis of converted products showed that the concentrations of four RH-9129 and RH-9130 stereoisomers were different from each other under both aerobic and anaerobic conditions. The four stereoisomer concentrations followed the order (-)-RH-9129 > (+)-RH-9129 > (-)-RH-9130 > (+)-RH-9130 in Langfang alkaline soil. However, in the case of Changsha acidic soil, different RH-9129 and RH-9130 stereoisomer patterns were produced in the order (-)-RH-9129 > (+)-RH-9129 > (+)-RH-9130 > (-)-RH-9130. The (-)-RH-9129 stereoisomer had the highest concentration formed by transformation of fenbuconazole in both soils. The degradation of RH-9129 and RH-9130 in the two soils is also stereoselective under both aerobic and anaerobic conditions, the results indicating that the (+)-RH-9130 enantiomer degraded faster than the (-)-RH-9130 enantiomer and the (+)-RH-9129 enantiomer degraded faster than the (-)-RH-9129 enantiomer. In addition, the (-)-RH-9129 isomer exhibited the slowest degradation rate in both soils. This study provides the first experimental evidence of stereoselective degradation and transformation of fenbuconazole as well as its chiral metabolites in the environment.
戊唑醇是一种广泛使用的三唑类内吸性农用杀菌剂，具有一个手性中心。本研究采用手性 OD-RH 柱在反相液相色谱-串联质谱系统中，研究了戊唑醇及其手性代谢物 RH-9129 和 RH-9130 在两种土壤中好氧和厌氧条件下的对映体选择性降解。在好氧或厌氧条件下，结果表明存在对映体选择性，(-)-戊唑醇优先在两种土壤中降解。进一步对转化产物的对映体选择性分析表明，在好氧和厌氧条件下，四种 RH-9129 和 RH-9130 立体异构体的浓度彼此不同。在廊坊碱性土壤中，四种立体异构体的浓度顺序为(-)-RH-9129＞(+)-RH-9129＞(-)-RH-9130＞(+)-RH-9130。然而，在长沙酸性土壤中，RH-9129 和 RH-9130 产生了不同的立体异构体模式，顺序为(-)-RH-9129＞(+)-RH-9129＞(+)-RH-9130＞(-)-RH-9130。(-)-RH-9129 立体异构体是两种土壤中由戊唑醇转化生成的浓度最高的异构体。在好氧和厌氧条件下，RH-9129 和 RH-9130 在两种土壤中的降解也是对映体选择性的，结果表明(+)-RH-9130 对映体的降解速度快于(-)-RH-9130 对映体，(+)-RH-9129 对映体的降解速度快于(-)-RH-9129 对映体。此外，(-)-RH-9129 异构体在两种土壤中的降解速度最慢。本研究首次提供了环境中戊唑醇及其手性代谢物对映体选择性降解和转化的实验证据。
