An ultrasensitive LC-MS/MS method for the determination of glyphosate, AMPA and glufosinate in water-analysis of surface and groundwater from a hydrographic basin in the Midwestern region of Brazil

The intensive use of glyphosate around the world in the last few decades demands constant monitoring of this com-pound and its metabolite in aquatic compartments. This work aimed to develop a sensitive method for the analysis of glyphosate, AMPA and glufosinate in water by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The method involves analyte concentration by lyophilization (20x) and direct injection on the LC-MS/MS, and was satisfactorily validated at a LOQ of 0.0025 mu g L-1. A total of 142 samples of surface and groundwater collected during the 2021/2022 dry and rainy seasons in the Rio Preto Hydrographic Basin were analyzed. All the 52 groundwater sam-ples were positive for glyphosate (up to 1.5868 mu g L-1, dry season) and AMPA (up to 0.2751 mu g L-1, dry season). A total of 27 of the 90 surface water samples were positive for glyphosate (up to 0.0236 mu g L-1), and 31 samples for AMPA (up to 0.0086 mu g L-1), of which over 70 % collected during the dry season. Glufosinate was detected in only five samples, four in groundwater (up to 0.0256 mu g L-1). The levels found in the samples are much lower than the max-imum levels established by the Brazilian legislation for glyphosate and/or AMPA and lower than the most critical tox-icological endpoints for aquatic organisms. However, constant monitoring is necessary, demanding sensitive methods to allow the detection of the very low levels of these pesticides in water.

Automated summary

A sensitive method for the analysis of glyphosate, AMPA, and glufosinate in water was developed using liquid chromatography/tandem mass spectrometry. The results showed that glyphosate and AMPA were frequently detected in groundwater and surface water, but their concentrations were below the maximum levels allowed by Brazilian legislation and below the most critical toxicological endpoints for aquatic organisms. However, continuous monitoring is necessary due to the widespread use of glyphosate worldwide.