Monitoring plans are implemented to analyze the presence of pesticides in foodstuffs. Currently, liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is recognized as a reference tool for multi-residue analysis of pesticides due to its specificity and sensitivity. This technique remains limited to a known list of substances to be searched for, which can pose a problem of exhaustiveness. In fact, many anthropic molecules not researched are likely to be found in the analyzed food. High resolution mass spectrometry (HRMS) allows the detection of a large number of molecules by different approaches (targeted, suspect, non-targeted), making it possible to fill the lack of exhaustiveness of conventional analyses.<br/>Through this thesis, we aim to : (1) Develop "targeted" multi-residue QuEChERS/QuPPE-LC-HRMS analytical method(s) that covers the broadest spectrum of contaminants (&gt;800 pesticides, &gt;150 veterinary drugs, &gt;100 pharmaceuticals) and matrices (animal and vegetal foodstuffs); (2) In parallel, we are evaluating the identification criteria used in HRMS, for which no consensus has been established; (3) These "targeted" methods will be applied to set up a monitoring plan in collaboration with the ANSES Risk Assessment Department (DER). The collected and analyzed samples will allow us to build a "Spectrotheque" for retrospective analysis; (4) Finally, we will evaluate the most used and efficient chemometric tools for "non-targeted" analysis, in order to elucidate the cases of collective food poisoning (CFP) efficiently.<br/>For now, we started the phase (1) of analytical development by choosing baby-foods as model matrices. Their great matrix heterogeneity make them very relevant and suitable for the development of an exhaustive method in terms of matrix. These baby foods were supplemented with a mix of 204 pesticides. After a review of the literature, different conditions were evaluated: (a) The extraction condition with different extraction / purification procedures; (b) The chromatographic condition with different gradient times and mobile phases; (c) The mass spectrometry condition where two source temperatures were compared between them, as well as different acquisition modes used in HRMS. At the same time, the data generated will have allowed us to begin phase (2) of evaluating the identification criteria used in HRMS.  Further analytical development will be carry on a wider spectrum of contaminants (&gt;800) and matrix variety.

Screening of pesticides in foodstuffs by high-resolution mass spectrometry: Targeted and non-targeted approaches

ACS Fall 2021

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