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Synthesis and characterization of molecularly imprinted polymers for the selective extraction of organophosphorus pesticides from vegetable oils

Abstract : The increasing use of pesticides in agriculture causes serious health risks to humans. These pesticides may possibly be found in vegetable oils used as cosmetic ingredients. Their identification and reliable quantitative analysis at trace levels constitute a challenge for the safe use of such oils despite the high potential of analytical methods such as liquid chromatography coupled to mass spectrometry (LC-MS/MS). Their determination at low concentration levels in complex oil samples requires an extraction and a purification step. In order to increase the selectivity of the sample treatment step, the synthesis of imprinted sorbents can be considered. This study focusses on a group of pesticides, the organophosphorus (OPs) that present some structural disparity and belong to a wide range of polarity (log P values between 0.7 and 4.7). To produce imprinted sorbents, a first approach of synthesis consists in the radical polymerization of organic monomers in moderately polar organic solvents to obtain molecularly imprinted polymers (MIPs). The second one, the Sol-Gel approach, consists in the hydrolysis and then condensation of organosilanes in a polar medium to produce molecularly imprinted silicas (MIS). For both approaches, different conditions of synthesis were screened using different template molecules, monomers and solvents. The selectivity of the resulting imprinting polymers was first evaluated by studying the extraction profiles of OPs in pure media on MIP and MIS. The non-specific interactions were estimated by studying in parallel the retention of OPs on non-imprinted polymers synthesized in the same conditions as imprinted sorbents but in the absence of the template molecule. Both sorbents MIP/MIS present a complementarity in terms of selective extraction of the target OPs: polar OPs were extracted selectively using the MIS while moderately polar OPs were selectively extracted by the MIP. The capacity of these supports was evaluated and was consistent with the analysis of OPs at trace levels in real oil samples. After studying the repeatability of the extraction procedure and of the reliability of the syntheses, the performances of these supports were studied in real media. For this, MIP/MIS were applied to the selective extraction of OPs from different vegetable oils (almond, olive and sunflower oil) and similar results were obtained for the three different oils. Their potential in terms of ability to remove matrix interfering compounds were higher than those of the conventional method based on the use of C18 silica. The estimated limits of quantifications were lower than the Maximum Residue Levels (MRLs) established by EU Regulation 396/2005 for these compounds in oils.
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  • HAL Id : tel-01680840, version 2

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Sara Boulanouar Al Massati. Synthesis and characterization of molecularly imprinted polymers for the selective extraction of organophosphorus pesticides from vegetable oils. Analytical chemistry. Université Pierre et Marie Curie - Paris VI, 2017. English. ⟨NNT : 2017PA066204⟩. ⟨tel-01680840v2⟩

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