ABSTRACT Modern agricultural technology is based on a package that combines direct seeding and glyphosate with transgenic crops (soybean, maize, and cotton). Because of widespread glyphosate use, it is important to assess its impact on the environment. However, glyphosate's unique physicochemical characteristics make determination difficult at residue concentrations, especially in soils with high organic matter content, such as the soils from the central eastern region of Argentina, where strong analytical interferences are normally observed. The aim of this work was to compare the efficiency of two extraction methods of glyphosate using representative soils from Argentina. One method is based on the use of a phosphate buffer as the extracting solution and dichloromethane to minimize matrix organic content. The other method uses potassium hydroxide for the soil extraction of analytes and involves a cleanup step using solid phase extraction to minimize analytical interferences. Both methodologies involve a derivatization with 9-fluorenyl-methyl-chloroformate in borate buffer, the use of isotope labeled glyphosate as an internal standard, and detection based on ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry. Recoveries obtained for soil samples spiked at 100 and 1000 &mgr;g kg−1 were satisfactory in both methods (70%–120%). However, significant differences were observed in the effects on the organic matrix. The solid phase extraction cleanup step was insufficient to remove the interferences, whereas the dilution and the cleanup with dichloromethane were more effective in minimizing the ionic suppression.

中文翻译：

---

两种提取方法测定土壤中草甘膦和氨基甲基膦酸的评价

摘要 现代农业技术基于将直播和草甘膦与转基因作物（大豆、玉米和棉花）相结合的一揽子计划。由于草甘膦的广泛使用，评估其对环境的影响非常重要。然而，草甘膦独特的理化特性使残留浓度的测定变得困难，特别是在有机质含量高的土壤中，例如阿根廷中东部地区的土壤，通常会观察到强烈的分析干扰。这项工作的目的是使用阿根廷的代表性土壤比较两种草甘膦提取方法的效率。一种方法是基于使用磷酸盐缓冲液作为提取溶液和二氯甲烷来最小化基质有机物含量。另一种方法使用氢氧化钾对分析物进行土壤萃取，并涉及使用固相萃取的净化步骤，以最大程度地减少分析干扰。这两种方法都涉及在硼酸盐缓冲液中用 9-芴基-甲基-氯甲酸酯衍生化，使用同位素标记的草甘膦作为内标，以及基于超高效液相色谱与串联质谱联用的检测。两种方法中添加 100 和 1000 &mgr;g kg-1 的土壤样品获得的回收率均令人满意 (70%–120%)。然而，观察到对有机基质的影响存在显着差异。固相萃取净化步骤不足以消除干扰，而稀释和用二氯甲烷净化在最大限度地减少离子抑制方面更有效。