Martin Pedro J, He Ke, Blaney Lee, Hobbs Shakira R
Department of Civil & Environmental Engineering, Samueli School of Engineering, University of California, Irvine, Irvine, California 92697, United States.
Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, Maryland 21250-0001, United States.
ACS ES T Water. 2023 May 24;3(8):2407-2414. doi: 10.1021/acsestwater.3c00094. eCollection 2023 Aug 11.
Analytical limitations make it challenging to develop effective methodologies for understanding glyphosate-based herbicide levels in drinking water and groundwater. Due to their lack of chromophores and zwitterionic nature, glyphosate-based herbicides are difficult to detect using traditional methods. This paper offers a straightforward method for quantifying glyphosate, glufosinate, and aminomethylphosphonic acid (AMPA) via 9-fluorenylmethylchloroformate (FMOC-Cl) pre-column derivatization and analysis by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Method development was focused on optimizing the critical variables for optimal derivatization using a 2-factorial design. We found that complete derivatization significantly depends on the inclusion of borate buffer to create the alkaline conditions necessary for aminolysis. Ethylenediaminetetraacetic acid (EDTA) addition was critical to minimize metallic chelation and ensure reproducible retention times and peaks. However, EDTA concentrations ≥5% decreased peak intensity due to ion suppression. The FMOC-Cl concentration and derivatization time exhibited a direct proportional relationship, with the complete reaction achieved with 2.5 mM FMOC-Cl after 4 h. Concentrations of FMOC-Cl greater than 2.5 mM led to the formation of oxides, which interfere with the detection sensitivity and selectivity. Desirable results were achieved with 1% EDTA, 5% borate, and 2.5 mM FMOC-Cl, which led to complete derivatization after 4 h.
分析上的局限性使得开发有效的方法来了解饮用水和地下水中基于草甘膦的除草剂水平具有挑战性。由于基于草甘膦的除草剂缺乏发色团且具有两性离子性质，因此使用传统方法难以检测。本文提供了一种直接的方法，通过9-芴基甲基氯甲酸酯（FMOC-Cl）柱前衍生化和液相色谱-串联质谱（LC-MS/MS）分析来定量草甘膦、草铵膦和氨甲基膦酸（AMPA）。方法开发侧重于使用二因素设计优化关键变量以实现最佳衍生化。我们发现完全衍生化很大程度上取决于加入硼酸盐缓冲液以创造氨解所需的碱性条件。添加乙二胺四乙酸（EDTA）对于最小化金属螯合并确保保留时间和峰的重现性至关重要。然而，EDTA浓度≥5%会由于离子抑制而降低峰强度。FMOC-Cl浓度和衍生化时间呈正比关系，4小时后使用2.5 mM FMOC-Cl可实现完全反应。FMOC-Cl浓度大于2.5 mM会导致氧化物形成，这会干扰检测灵敏度和选择性。使用1% EDTA、5%硼酸盐和2.5 mM FMOC-Cl可获得理想结果，4小时后可实现完全衍生化。
