Rijkswaterstaat, Ministry of Infrastructure and the Environment, P.O. Box 17, 8200, AA Lelystad, the Netherlands.
Rijkswaterstaat, Ministry of Infrastructure and the Environment, P.O. Box 17, 8200, AA Lelystad, the Netherlands.
Anal Chim Acta. 2020 Oct 9;1133:66-76. doi: 10.1016/j.aca.2020.05.058. Epub 2020 Jul 20.
This paper describes a simple and reliable method for the sensitive and selective determination of the pesticides Glyphosate and Glufosinate and their main metabolites aminomethylphosphonic acid (AMPA) and 3-[hydroxy(methyl)phosphinoyl]propionic acid (MPPA) in surface water. The developed method is based on ion chromatography hyphenated to electrospray tandem mass spectrometry and does not require derivatization. A membrane suppressor, regenerated at pH 9, has been used in this work to strongly improve the peak shape of AMPA, which suffered from huge tailing due to the interaction of this compound with acidic membrane suppressors. With this modified suppressor the sensitivity for AMPA improved about 100 times. Moreover, addition of 40% methanol to the hydroxy eluent improved MS sensitivity for all compounds by 1.3-2.8 times. The separation is performed on a strong anion exchange column. Glyphosate and AMPA are detected in the negative ion ESI mode, whereas Glufosinate and MPPA show much better sensitivity in the positive ion ESI mode. Surface water samples were spiked with the labelled parent compounds. Sample preparation comprised a filtering step over coupled solid phase extraction Ba, Ag and Na cartridges to remove chloride and sulphate ions. The performance characteristics of the method were determined with real surface water samples. Samples containing 12.6 g L chloride were also used in the validation process and showed no problem. Nitrate is not removed from the samples and may give ion-suppression for Glyphosate. Linearity of the method was established over at least three orders of magnitude in the measuring range 10-2000 ng L for surface water. The reliability of the results was ensured by the application of the criteria from the Dutch Technical Agreement (NTA 8379) concerning "identification", "indication", and "absence" of substances. The limit of quantitation with regard to identification was 10 ng L for all compounds and the limits of detection with regard to indication were 6.5-9.6 ng L. The recovery (94-104%) and reproducibility variance (5.5-6.2%) were excellent. The suitability of the developed method was demonstrated by the analysis of 172 surface water samples of low to moderate salinity from different parts of The Netherlands. AMPA was identified in 99% of the samples and always exceeded the maximum allowable concentration of 100 ng L. The maximal concentration found in surface water was 9900 ng L. Glyphosate was identified in 82% of the samples and in only 6% Glyphosate exceeded the maximum allowable concentration of 100 ng L. MPPA was identified in about 75% of the samples whereas Glufosinate was rarely detected and never exceeded the limit of quantitation.
本文描述了一种灵敏、选择性测定地表水中农药草甘膦和草铵膦及其主要代谢物氨甲基磷酸（AMPA）和 3-[羟基（甲基）膦酰基]丙酸（MPPA）的简单可靠方法。所开发的方法基于离子色谱-电喷雾串联质谱联用技术，不需要衍生化。在这项工作中，使用了一种在 pH 9 下再生的膜抑制器，可大大改善 AMPA 的峰形，由于该化合物与酸性膜抑制器相互作用，AMPA 的峰形严重拖尾。使用这种改良的抑制器，AMPA 的灵敏度提高了约 100 倍。此外，在羟基洗脱液中加入 40%甲醇可使所有化合物的 MS 灵敏度提高 1.3-2.8 倍。分离在强阴离子交换柱上进行。草甘膦和 AMPA 在负离子 ESI 模式下检测，而草铵膦和 MPPA 在正离子 ESI 模式下显示出更好的灵敏度。地表水样用标记的母体化合物进行了加标。样品制备包括通过偶联固相萃取 Ba、Ag 和 Na 柱过滤步骤，以去除氯化物和硫酸盐离子。该方法的性能特征用实际的地表水样本进行了测定。在验证过程中还使用了含有 12.6 g/L 氯化物的样品，没有出现问题。硝酸盐不会从样品中去除，可能会对草甘膦产生离子抑制。该方法在 10-2000 ng/L 的测量范围内至少建立了三个数量级的线性关系。结果的可靠性通过应用荷兰技术协议（NTA 8379）中关于“识别”、“指示”和“不存在”物质的标准来保证。所有化合物的定量限为 10 ng/L，指示限为 6.5-9.6 ng/L。回收率（94-104%）和重现性方差（5.5-6.2%）非常出色。该方法的适用性通过分析来自荷兰不同地区的 172 个低至中等盐度的地表水样本得到了证明。AMPA 在 99%的样品中被识别，并且始终超过 100 ng/L 的最大允许浓度。在地表水中发现的最大浓度为 9900 ng/L。草甘膦在 82%的样品中被识别，只有 6%的草甘膦超过 100 ng/L 的最大允许浓度。MPPA 在约 75%的样品中被识别，而草铵膦很少被检测到，从未超过定量限。
