Determination of environmental levels of glyphosate and AMPA in water, sediment and soil samples of the Pampas Region, Argentina

DAMIÁN MARINO; JEZABEL PRIMOST; YANINA ELORRIAGA; ALICIA RONCO; PEDRO CARRIQUIRIBORDE

Berlin

Congreso; congreso 6th SETAC World Congress/ SETAC Europe 22nd Annual Meeting Berlin; 2012

SETAC

In the last 30 years, agriculture in Argentina and other developing countries has markedly expanded. In particular, the surface of soybean crop has increased 10-fold since the 80’s. The Pampas Region is the main agriculture district of Argentina. According with current agriculture practices, Glyphosate is the major soybean herbicide. Due to the molecular multifunctional structure, this compound presents a complex environmental behavior. Its speciation and complex coordination depends on the pH, MO and free ions (i.e. metals). Regional variations in the nature of the chemical matrices demands adjustments of the analytical methods for glyphosate determination depending of the soils and water chemistry. The aim of this presentation is to report environmental levels of glyphosate, and its major metabolite the aminomethylphosphonic acid (AMPA),obtained in the last five years using methods optimized in our laboratory for the analysis of water, sediment and soil samples of the Pampas Region, Argentina. Detection method was based on HPLC-MS after alkaline derivatization using FMOC-CL. Isotopic tracers were used for quality assurance. A total number of 250 water samples (surface and groundwater) and 70 sediments and soil samples were analyzed. Chromatographic conditions, particularly MeOH/H2O gradient, were critical for eliminating matrix interferences. The highest instrumental sensitivity was obtained using ESI interface in negative mode, monitoring the M-H product of the derivatization (glyphosate-FMOC:m/z 390, AMPA: m/z 332). Detection limits for both analytes were 0.5 μg/l for water samples and 5 μg/Kg for soils and sediments. Recoveries were higher than 95% for water samples and between 85-95% for the solid matrices. In surface waters, 25% of the samples were positive with concentrations between 1-400 μg/l. None of the groundwater samples yielded positive results. Levels in soils and sediments were between 2-300 μg/Kg, with 40 and 10% of the samples presenting levels above the detection limit,respectively. Optimized methods were suitable for detecting glyphosate and AMPA in different environmental matrices, demonstrating the occurrence of these compounds in surface waters, sediments and soils of the Pampas Region. On the other hand, glyphosate and AMPA, seems not to readily lixiviate and reach groundwater.