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  • Title: Application of solid-phase microextraction for determining phenylurea herbicides and their homologous anilines from vegetables.
    Author: Berrada H, Font G, Moltó JC.
    Journal: J Chromatogr A; 2004 Jul 09; 1042(1-2):9-14. PubMed ID: 15296383.
    Abstract:
    Residues of metobromuron, monolinuron and linuron herbicides and their aniline homologous were analyzed in carrots, onions and potatoes by solid-phase microextraction (SPME) performed with a polyacrylate fiber. A juice was obtained from food samples that were further diluted, and an aliquot was extracted after sodium chloride (14%) addition and pH control. At pH 4 only the phenylureas were extracted. A new extraction at pH 11 allowed the extraction of phenylureas plus homologous aniline metabolites. Determination was carried out by gas chromatography with nitrogen-phosporus detection (NPD) the identity of the determined compounds was studied by gas chromatography-mass spectrometry. Limits of quantification (LOQs) obtained with NPD and MS (selected-ion monitoring) were in the microg/kg order allowing determination of maximum residue levels (MRLs) established in the Spanish regulations. MRLs ranged from 0.02 to 0.1 mg/kg depending on the kind of food and herbicide. Under the proposed conditions matrix effects were low enough to permit calibration with samples proceeding from ecological (non-pesticide treated) crops. Twelve commercial samples of each carrots, onions and potatoes were analyzed and only three samples of potatoes contained residues of linuron at levels below MRLs.
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