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

REPETTI MR; DE JESÚS JJ; LUQUE EH; MILESI MM; BELDOMÉNICO H; DEMONTE LD

Munich

Workshop; 12th European Pesticide Residue Workshop; 2018

Since1996, culture areas destined to genetically modified crops have been extendedmostly in South American countries like Argentina, Brazil, Bolivia, Paraguayand Uruguay, and Glyphosate has become the most globally used herbicide.Additionally, in the last decade farmers increased glyphosate application ratesand use it more often to combat glyphosate-resistant weeds. Lately, other useshave been found for glyphosate as desiccants in the growing season toaccelerate harvest operations, especially in small grain crops. Given theextensive and increased used of this herbicide, levels of glyphosate and itsprimary metabolite aminomethylphosphonic acid (AMPA) have been detected in theair, soil, respirable dust, water, as well as in foods that can be consumed byhumans or livestock. In addition, a trend towards increasing glyphosateconcentrations was detected in urine samples from farm and non-farm individualsin Europe. These evidences show that there is a risk of environmental exposureto glyphosate, stressing concerns about its potential effects on human health. Furthermore,some research works on glyphosate revealed endocrine disruption indicativeeffects of this pesticide. In this work a simple, rapid and robust methodfor the determination of glyphosate, AMPA and glufosinate ammonium in serumsamples was optimized and validated by UHPLC-MS/MS. The method consists in afirst protein precipitation step with acetonitrile and then a derivatizationwith 9-fluorenilmethylchloroformate (FMOC-Cl), reaction that is carried out atroom temperature for 2 hours, followed by liquid-liquid extraction with dichloromethaneas a cleanup step. Satisfactory results have been obtained showing that thismethod is consistent and reliable, with low RSD values and good recoverybetween 90-130 % at two concentration levels (LOQ and 10 µg/L) and with a LODof 1 µg/L. This method was then applied incollaborative studies evaluating glyphosate indicative endocrine disruptioneffects in rat, sheep and human serum. It also shows some advantages incomparison with other existing approaches, contributing to the challenge of measuringthe glyphosate family with simpler, economical and reliable methodologies.