Determination of glyphosate, AMPA and glufosinate in serum by UHPLC-MS/MS

DEMONTE, LUISINA D.; MILESI, MARÍA M.; DE JESÚS, JUAN JOSÉ; BELDOMÉNICO, HORACIO R.; LUQUE, ENRIQUE H.; REPETTI, MARÍA R.

Munich

Workshop; 12th European Pesticide Residue Workshop; 2018

Since 1996, culture areas destined to genetically modified crops have been extended mostly in South American countries like Argentina, Brazil, Bolivia, Paraguay and Uruguay, and Glyphosate has become the most globally used herbicide. Additionally, in the last decade farmers increased glyphosate application rates and use it more often to combat glyphosate-resistant weeds. Lately, other uses have been found for glyphosate as desiccants in the growing season to accelerate harvest operations, especially in small grain crops. Given the extensive and increased used of this herbicide, levels of glyphosate and its primary metabolite aminomethylphosphonic acid (AMPA) have been detected in the air, soil, respirable dust, water, as well as in foods that can be consumed by humans or livestock. In addition, a trend towards increasing glyphosate concentrations was detected in urine samples from farm and non-farm individuals in Europe. These evidences show that there is a risk of environmental exposure to glyphosate, stressing concerns about its potential effects on human health. Furthermore, some research works on glyphosate revealed endocrine disruption indicative effects of this pesticide. In this work a simple, rapid and robust method for the determination of glyphosate, AMPA and glufosinate ammonium in serum samples was optimized and validated by UHPLC-MS/MS. The method consists in a first protein precipitation step with acetonitrile and then a derivatization with 9-fluorenilmethylchloroformate (FMOC-Cl), reaction that is carried out at room temperature for 2 hours, followed by liquid-liquid extraction with dichloromethane as a cleanup step. Satisfactory results have been obtained showing that this method is consistent and reliable, with low RSD values and good recovery between 90-130 % at two concentration levels (LOQ and 10 µg/L) and with a LOD of 1 µg/L. This method was then applied in collaborative studies evaluating glyphosate indicative endocrine disruption effects in rat, sheep and human serum. It also shows some advantages in comparison with other existing approaches, contributing to the challenge of measuring the glyphosate family with simpler, economical and reliable methodologies.