Department of Chemistry and Biochemistry and Southeast Environmental Research Center, Florida International University, Miami, FL, USA.
United States National Park Service, Biscayne National Park, Homestead, FL, USA.
Sci Total Environ. 2014 Oct 15;496:389-401. doi: 10.1016/j.scitotenv.2014.06.118. Epub 2014 Aug 2.
A novel method was developed for the analysis of the herbicide glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) based on lyophilization. Sample preparation steps are limited to fortification with aspartic acid as internal standard and water removal by lyophilization (3-4 days for 72 samples), followed by suspension of dry residues in borate buffer (pH=9.0) and addition of ethylenediaminetetraacetic acid (EDTA) and 9-fluorenylmethylchloroformate (FMOC-Cl) for pre-column derivatization. The obtained derivatization mixture was injected on a highly endcapped C18 column where a basic pH gradient separation of the anionic analytes from neutral derivatization byproducts was achieved, with simultaneous quantitation by fluorescence and compound confirmation by tandem mass spectrometry. Method detection limits (for 20 mL samples) were 0.058 μg/L and 0.108 μg/L for glyphosate and AMPA, respectively. The method had a high dynamic range (0.1-50.0 μg/L) which allowed quantitation at both background and high levels of the herbicide. As a case study, the methodology was successfully applied to detect the occurrence of these compounds in water canals managed by the South Florida Water Management District. These canals will be used as freshwater source to hydrate estuarine wetlands of Biscayne National Park under the Comprehensive Everglades Restoration Project, in order to decrease ecosystem stress from hypersaline conditions caused by anthropogenic reduction of historical freshwater flow towards the Biscayne Bay. Method development, validation, advantages, limitations and measured environmental concentrations are discussed. This methodology has minimal requirements in terms of materials, instruments and analyst training, which could represent a desirable tool for laboratories interested in the monitoring of glyphosate in surface waters.
开发了一种基于冻干的新型方法，用于分析除草剂草甘膦及其主要代谢物氨甲基膦酸（AMPA）。样品制备步骤仅限于用天冬氨酸作为内标进行强化，并通过冻干去除水分（72 个样品需要 3-4 天），然后将干残余物悬浮在硼酸盐缓冲液（pH=9.0）中，并加入乙二胺四乙酸（EDTA）和 9-芴甲基氯甲酸酯（FMOC-Cl）进行柱前衍生化。所得衍生化混合物被注入高度端封的 C18 柱上，其中在碱性 pH 梯度下，从中性衍生化副产物中分离阴离子分析物，同时通过荧光定量，并通过串联质谱进行化合物确证。方法检测限（对于 20 毫升样品）分别为草甘膦和 AMPA 的 0.058 μg/L 和 0.108 μg/L。该方法具有高动态范围（0.1-50.0 μg/L），允许在背景和除草剂高水平下定量。作为案例研究，该方法成功应用于检测南佛罗里达水资源管理区管理的运河中这些化合物的发生情况。这些运河将作为淡水来源，用于为比斯坎国家公园的河口湿地供水，这是全面大沼泽地恢复项目的一部分，目的是减少由于人为减少流向比斯坎湾的历史淡水流量而导致的生态系统盐分胁迫。讨论了方法开发、验证、优点、局限性和测量的环境浓度。该方法在材料、仪器和分析师培训方面的要求最低，这可能是对有兴趣监测地表水草甘膦的实验室的理想工具。
