Glyphosate and other highly polar pesticides in fruit, vegetables and honey using ion chromatography coupled with high resolution mass spectrometry: Method validation and its applicability in an official laboratory.

An analytical method, using ion chromatography coupled to high resolution mass spectrometry was developed and validated to quantify glyphosate, glufosinate, ethephon, fosetyl aluminium and their related metabolites. This method allows multiresidue analysis of 11 highly polar molecules in a single chromatographic run, without derivatization step, using acidified water with low level of acetonitrile as extraction solvent. Three different matrices that are representative of commodity group were studied and validated: one fruit (grapes), one cereal (wheat) and honey, according to the criteria established by SANTE/12682/2019 taking into account maximum residue limits indicated by Regulation (EC) No. 396/2005, confirming that the procedure was selective, repeatable and robust. Matrix effect was studied and linearity was evaluated comparing analytical response differences between solvent standard solutions and matrix-matched calibration curve. Due to the relevant matrix effect observed, the use of response factor (RF) approach to quantify analytical batch was evaluated, using isotopically labelled internal standardisation. The in-depth study, validation results and several proficiency tests, used to verify procedure performance, demonstrated that the method is fit for purpose to routine analysis in an official laboratory. Moreover, it allows surveillance activities in fruits and vegetables control, as indicated by European Community, furthermore monitoring presence of polar pesticides, at low level, in some particular food as honey that could become environmental pollution indicator.