Determination of glyphosate, AMPA and glufosinate in honey.

MAGNI, FLORENCIA V.; RAATS, DAIANA G.; DEMONTE, LUISINA D.; MICHLIG, NICOLÁS; REPETTI, MARÍA R.; MICHLIG, MELINA P.; BELDOMÉNICO, HORACIO R.

Foz do Iguazú

Workshop; 7th Latin American Pesticide Residue Workshop; 2019

CEPARC-UFSM

Argentina dramatically transformed its agriculture based on important technological innovations. These changes included the extensive adoption of Genetically Modified (GM) crops designed to be resistant to specific herbicides, mainly glyphosate (N-(phosphonomethyl) glycine) and glufosinate ((3-amino-3- carboxypropyl)methyl phosphinic acid). Glyphosate is a broad-spectrum, non-selective herbicide used for the control in preemergence weed and as a pre-harvest desiccation agent, being other non-agricultural uses also registered. Because of this, chemical residues at low concentrations might be found in food, water, soils and other environmental samples, increasing exposure to humans and animals through their diets. Honey samples obtained from numerous different countries were found to contain glyphosate residues. Glyphosate and related compounds present difficulties for chemical analysis through conventional chromatographic-mass spectrometric methods, currently applicable in multi-residue approaches. Its physico-chemical characteristics (polar, amphoteric with 4 pKa values, low atomic mass) introduce specific problems in the separation and detection stages. Despite several novel methodologies mainly based in advanced instrumentation have been proposed, an efficient and simple methodology to solve this group of pesticides is still a challenge. In this frame, derivatization with FMOC-Cl is still a valuable option due to some of its advantages (the suitability for using reverse phase chromatography, the improvement of retention in LC, the increase in molecular weight and sensitivity, the reproducibility of the reaction, and the very competitive LOQs) even when it is applied to complex samples such as bee honey.This work presents a simple method for the quantification of glyphosate, its major metabolite aminomethylphosphonic acid (AMPA) and glufosinate in honey samples based in FMOC-Cl derivatization and UHPLC-MS/MS. The methodology involves an extraction step followed by the derivatization reaction and finally L-L partition with dichloromethane. Sample preparation development assays involved optimization of extraction conditions and derivatization (different FMOC-Cl concentrations, reaction time and cleanup process). Satisfactory results have been obtained, showing that this method is consistent and reliable, with low RSDs and good recovery between 70-120%. Data of applications on experimental studies with real samples is also presented.