title: Dual-layer solid-phase extraction based on molecular imprinting technology: Seeking a route to enhance selectivity for trace analysis of pesticide residues in olive oil.
abstract: Aiming to introduce a multiresidue analysis for the trace detection of pesticide residues belonging to organophosphorus and triazine classes from olive oil samples, a new sample preparation methodology comprising the use of a dual layer of "tailor-made" molecularly imprinted polymers (MIPs) SPE for the simultaneous extraction of both pesticides in a single procedure has been attempted. This work has focused on the implementation of a dual MIP-layer SPE procedure (DL-MISPE) encompassing the use of two MIP layers as specific sorbents. In order to achieve higher recovery rates, the amount of MIP layers has been optimized as well as the influence of MIP packaging order. The optimized DL-MISPE approach has been used in the preconcentration of spiked organic olive oil samples with concentrations of dimethoate and terbuthylazine similar to the maximum residue limits and further quantification by HPLC. High recovery rates for dimethoate (95%) and terbuthylazine (94%) have been achieved with good accuracy and precision. Overall, this work constitutes the first attempt on the development of a dual pesticide residue methodology for the trace analysis of pesticide residues based on molecular imprinting technology. Thus, DL-MISPE constitutes a reliable, robust, and sensitive sample preparation methodology that enables preconcentration of the target pesticides in complex olive oil samples, even at levels similar to the maximum residue limits enforced by the legislation.
authors.affiliation: ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, IIFA, Universidade de Évora, Évora, Portugal.|LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Garcia
authors.affiliation: Centro de Química de Évora, IIFA, Universidade de Évora, Évora, Portugal.
authors.forename: Elisabete P
authors.initials: EP
authors.lastname: Carreiro
authors.affiliation: Centro de Química de Évora, IIFA, Universidade de Évora, Évora, Portugal.
authors.forename: José
authors.initials: J
authors.lastname: Nunes
authors.affiliation: LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
authors.forename: Marco Gomes
authors.initials: MG
authors.lastname: da Silva
authors.affiliation: Departamento de Fitotecnia, Escola de Ciências e Tecnologia, ICAAM, Universidade de Évora, Évora, Portugal.
authors.forename: Ana Maria Costa
authors.initials: AM
authors.lastname: Freitas
authors.affiliation: Centro de Química de Évora, IIFA, Universidade de Évora, Évora, Portugal.|Departamento de Química, Escola de Ciências e Tecnologia, Universidade de Évora, Évora, Portugal.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Burke
authors.affiliation: Departamento de Fitotecnia, Escola de Ciências e Tecnologia, ICAAM, Universidade de Évora, Évora, Portugal.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Cabrita
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D054802:Molecular Imprinting; D000069463:Olive Oil / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis*; D015203:Reproducibility of Results; D052616:Solid Phase Extraction / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000069463:Olive Oil; D010573:Pesticide Residues
keywords: Dimethoate; Dual-layer SPE; Molecularly imprinted polymers; Multiresidue analysis; Terbuthylazine