ANALYSIS OF GLYPHOSATE AND ITS DERIVATIVE, (AMINOMETHYL)PHOSPHONIC ACID, IN HUMAN SAMPLES BY GC/MS-MS AT LOW PPB LEVELS

FERNANDEZ, PILAR; JUNQUE, EVA; FILIPPI, IOHANNA; GRIMALT, JOAN O.

Almería

Congreso; XXI Scientific Meeting of the Spanish Society of Chromatography and Related Techniques; 2022

SECyTA

Glyphosate (N-(phosphonomethyl)glycine)) (GLY) is the active ingredient of the broad-spectrumherbicide “Roundup”. Since its commercial introduction in 1974 has rapidly become the mostextensively used herbicide worldwide. The main degradation product of GLY isaminomethylphosphonic acid (AMPA). The International Agency for Research on Cancerclassified GLY as “probable carcinogenic for humans" (category 2A) and several studies indicatea relation between GLY and different toxic effects in humans. Despite GLY and AMPA sorbstrongly to soils, these compounds have been found in environmental compartments, foodstuffand human samples. Although there are several analytical methods for the determination of GLYand AMPA, many of them reported insufficient limits of detection for the environmental orhuman biomonitoring studies.In the present study, a highly selective and sensitive gas chromatography coupled to tandemmass spectrometry (GC-MS-MS) method for the analysis of GLY and AMPA in human sampleshas been optimized. It includes previous esterification and acetylation of the acid and aminegroups to obtain less polar and more volatile compounds amenable for gas chromatographyanalysis. Several aspects have been studied to achieve low limits of detection (0.10 ng mL-1 forGLY and 0.30 ng mL-1 for AMPA).AMPA and GLY concentrations were determined by isotope dilution mass spectrometry (IDMS)using isotopic labeling of the target compounds with 13C and 15N; however, although there is amolecular mass difference of 3 units between the native and labelled compounds, the mainfragment in the spectra of GLY and labelled GLY only differs in 1 unit. This small differenceinvolves a spectral overlap resulting in cross contributions in peak areas between the native andlabelled compound transitions. The influence of this spectral overlap in the quantitative datawas assessed by comparison of the concentrations obtained by the classical IDMS procedurewith the method based on isotope pattern deconvolution (IPD). In this approach, the isotopecomposition of the sample after spiking is measured and deconvoluted into its components(molar fractions of natural and labelled compounds) by multiple linear regression. Oncevalidated, this method was applied to the determination of GLY and its derivate in human urinesamples from people living close to intensive agricultural area of Córdoba (Argentina).