Monkiedje Adolphe, Zuehlke Sebastian, Maniepi Saurelle Jacqueline Ngouopiho, Spiteller Michael
Institute of Environmental Research (INFU), University of Dortmund, Otto-Hahn-Strasse 6, D-44227 Dortmund, Germany.
Chemosphere. 2007 Sep;69(4):655-63. doi: 10.1016/j.chemosphere.2007.02.055. Epub 2007 Apr 9.
The elimination has been studied of racemic and enantioenriched metalaxyl applied as an emulsifiable concentrate and wettable powder combined with copper in a Cameroonian field site. The kinetics of the degradation/dissipation of metalaxyl and its acid metabolite were investigated using reversed phase HPLC-MS/MS, while the enantiomeric ratios were measured by HPLC-MS/MS using a Chiralcel OD-H HPLC column. Some soil enzymes activities were determined concurrently for 120d. The elimination of racemic metalaxyl was shown to be enantioselective, with the R-enantiomer being degraded more slowly than the S-enantiomer. Dissipation followed approximate square root first-order kinetics (R>0.98) without lag phases. The enantiomers of metalaxyl have different elimination rates, with half-lives ranging from only 0.8 to 1.5 days. After application to soil, the elimination of metalaxyl in the copper containing formulation was slower. The activities of acid phosphatase, alkaline phosphatase, and alkaline glucosidase were monitored throughout the experiments. No significant influence of metalaxyl and copper could be observed on these parameters. The significantly shorter half-life values of all forms of metalaxyl under field conditions, compared to the previously reported laboratory derived ones, may have implications for the plant disease control with these fungicides in tropical rainforest areas.
在喀麦隆的一块农田里，研究了外消旋甲霜灵以及对映体富集的甲霜灵以乳油和可湿性粉剂形式与铜结合施用后的消解情况。使用反相高效液相色谱-串联质谱法研究了甲霜灵及其酸性代谢物的降解/消散动力学，同时使用手性OD-H高效液相色谱柱通过高效液相色谱-串联质谱法测量对映体比例。同时测定了120天内一些土壤酶的活性。结果表明，外消旋甲霜灵的消解具有对映体选择性，R-对映体的降解速度比S-对映体慢。消散遵循近似平方根一级动力学（R>0.98），无滞后阶段。甲霜灵的对映体具有不同的消解速率，半衰期仅为0.8至1.5天。施用于土壤后，含铜制剂中甲霜灵的消解较慢。在整个实验过程中监测了酸性磷酸酶、碱性磷酸酶和碱性葡糖苷酶的活性。未观察到甲霜灵和铜对这些参数有显著影响。与先前报道的实验室数据相比，田间条件下所有形式甲霜灵的半衰期值明显更短，这可能会对热带雨林地区使用这些杀菌剂防治植物病害产生影响。
