title: Application of zirconium dioxide nanoparticle sorbent for the clean-up step in post-harvest pesticide residue analysis.
abstract: The use of yttria-stabilized zirconium dioxide nanoparticles as d-SPE clean-up sorbent for a rapid and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the determination of post-harvest fungicides (carbaryl, carbendazim, chlorpropham, diphenylamine, ethoxyquin, flutriafol, imazalil, iprodione, methomyl, myclobutanil, pirimiphos-methyl, prochloraz, pyrimethanil, thiabendazole, thiophanate-methyl and tolclofos-methyl) in orange and pear samples has been evaluated and validated. The sample preparation was a modification of the QuEChERS extraction method using yttria-stabilized zirconium dioxide and multi-walled carbon nanotubes (MWCNTs) nanoparticles as the solid phase extraction (d-SPE) clean-up sorbents prior to injecting the ten-fold diluted extracts into the LC system. By using the yttria-stabilized zirconium dioxide extraction method, more recoveries in the 70-120% range were obtained - thus this method was used for the validation. Quantification was carried out using a matrix-matched calibration curve which was linear in the 1-500 µg kg(-1) range for almost all the pesticides studied. The validated limit of quantification was 10 µg kg(-1) for most of the studied compounds, except chlorpropham, ethoxyquin and thiophanate-methyl. Pesticide recoveries at the 10 and 100 µg kg(-1) concentration levels were satisfactory, with values between 77% and 120% and relative standard deviations (RSD) lower than 10% (n=5). The developed method was applied for the determination of selected fungicides in 20 real orange and pear samples. Four different pesticide residues were detected in 10 of these commodities; 20% of the samples contained pesticide residues at a quantifiable level (equal to or above the LOQs) for at least one pesticide residue. The most frequently-detected pesticide residues were: carbendazim, thiabendazole and imazalil-all were below the MRL. The highest concentration found was imazalil at 1175 µg kg(-1) in a pear sample.
authors.affiliation: Agrifood Campus of International Excellence (ceiA3), European Union Reference Laboratory for Pesticide Residues in Fruit & Vegetables, University of Almeria, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Uclés
authors.affiliation: Agrifood Campus of International Excellence (ceiA3), European Union Reference Laboratory for Pesticide Residues in Fruit & Vegetables, University of Almeria, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Herrera López
authors.affiliation: National Institute for Agriculture and Food Research and Technology, INIA, 28040 Madrid, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Dolores Hernando
authors.affiliation: Department of Chemical Engineering, University of Alcalá, 28771 Alcalá de Henares, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rosal
authors.affiliation: Agrifood Campus of International Excellence (ceiA3), European Union Reference Laboratory for Pesticide Residues in Fruit & Vegetables, University of Almeria, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Ferrer
authors.affiliation: Agrifood Campus of International Excellence (ceiA3), European Union Reference Laboratory for Pesticide Residues in Fruit & Vegetables, University of Almeria, Spain. Electronic address: amadeo@ual.es.
authors.forename: Amadeo R
authors.initials: AR
authors.lastname: Fernández-Alba
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid; D032084:Citrus sinensis / Q000737:chemistry; D057230:Limit of Detection; D016014:Linear Models; D053758:Nanoparticles / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification*; D031989:Pyrus / Q000737:chemistry; D012449:Safety; D052616:Solid Phase Extraction / Q000191:economics / Q000379:methods*; D053260:Soot / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D010573:Pesticide Residues; D053260:Soot; D015019:Yttrium; D015040:Zirconium; C028541:zirconium oxide; C091417:yttria
keywords: Clean-up; LC–MS/MS; Pesticide residues; Post-harvest pesticides; Recoveries; Yttria-stabilized zirconium dioxide