Rugged LC-MS/MS method for the large-scale monitoring of glyphosate and other highly polar pesticides in soils across European Union olive orchards

Glyphosate (GLY) is the most widely used herbicide globally. Despite concerns regarding its potential adverse effects on human health and the environment, its use continues to grow each year. Following application, a substantial proportion of GLY infiltrates the soil, where it can degrade into transformation products such as aminomethylphosphonic acid (AMPA), which is much more persistent than the parent compound. Although these substances are widely distributed and pose potential environmental risks, their detection remains challenging due to their high polarity and ionic nature, which necessitates specialized analytical methodologies. In this work, it has been proposed a streamlined method for glyphosate and related anionic compounds based on solid-liquid extraction followed by direct LC-MS/MS using a polar anionic column and steering clear of a derivatization step. It avoids issues such as stationary phase passivation, retention time shifts, lack of analyte retention and reproducibility, unstable sensitivity, and poor performance over the course of a large set of samples. To assess the method's performance, it was applied to olive grove soil samples from the Mediterranean basin under different soil management systems (traditional, high-density, and organic). GLY and two of its main transformation products, AMPA and N-acetyl-AMPA, were identified in the studied samples. Soils under traditional and high-density management systems exhibited substantially higher concentrations compared to those under organic management. Regarding geographic trends, Portugal exhibited the highest average concentrations in soils under traditional and high-density management. In Spain and Morocco, high-density cultivars obtained the highest concentration, while in Greece, it was for traditional management. Trace concentrations of GLY and AMPA were also detected in organically managed soils in Portugal, Spain, and Greece.