Gyphosate in environmental samples from Argentina

REPETTI, MARÍA ROSA; DEMONTE, LUISINA; MICHLIG, NICOLÁS; GARCÍA, SILVIA R.; DE JESÚS, JUAN JOSÉ; BELDOMÉNICO, HORACIO R.

Santiago de Chile

Workshop; 5TH Latin American Pesticide Residue Workshop (LAPRW); 2015

FiNet, Facultad de Agronomía e Ingeniería Forestal (Universidad Católica de Chile).

Glyphosate (N-(phosphonomethyl) glycine) is the herbicide most used worldwide to control weeds and other uses, mostly due to the cultivation of GM glyphosate resistant crops. United States, Brazil and Argentina are the main demanding countries. Argentina started is wide use two decades ago and applies 200 mL/kg*L per annum since 2010. Glyphosate and glufosinate (ammonium(S)-2-amino-4-[hydroxyl (methyl) phosphinoyl] butyrate) are important chemical tools in the contemporary agriculture, that led to the sustained extraordinary growth of crop production (over 100 million tons of grains are annually produced in Argentina). This technological advances and economic success brought as counterpart an ehhancement of the concern to improve our knowledge on concatenated effects, and effectively control the potential impact on population health and environment. In this scenario the effectiveness of ligislation to guarantee sustainability, and the support from specific studies, monitoring and controls in food and environment, with aid of up-to-date methodologies, became of first importance.The analysis of glyphosate and related compounds as small polar ionic pesticides is still a challenge for residue analytical chemistry. Many options have been historically used including derivatization steps, being more recently introduced techniques of direct analysis. This presentation will describe the development and application of a simplified method for the determination of glyphosate, AMPA and glufosinate in water and sediments based in FMOC derivatization and UHPLC-MS/MS. Briefly the method, which includes the use of stable isotope labelled glyphosate, involves an overnight reaction step followed by L-L partition with dichloromethane. Optimization of sample preparation conditions, the FMOC derivatization steps (reagents, reaction time, pH), the clean-up process (solvents for L-L partition) as well as instrumental conditions, were carried out to achieve a good performance. Recoveries ranged between 85-110% at two concentration levels (LOQ and 100 ppb), the LODs were 0.2 ng/mL (gly and AMPA) and 0.02 ng/mL (glu) for waters and 0.4 ng/g (gly and AMPA) and 0.2 ng/g (glu) for sediments.Results of several applications of the methodology to the analysis of groundwater, superficial water and sediment samples from Santa Fe and other central provinces of Argentina, from various monitoring and special field studies, will be described.