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.

Molecularly imprinted polymers for the determination of organophosphorus pesticides in complex samples

“…To reach the same objective, a MIP a b c d was prepared using both molecules, monocrotophos and trichlorfon, as templates for the synthesis of a unique MIP [102]. A SPE sorbent specific to two different groups was also proposed by preparing a dual-layer cartridge containing both a MIP prepared with dimethoate as template (in synthesis conditions previously reported by Martins et al [58]) and a MIP prepared using terbuthylazine as template for the simultaneous determination of both targets in olive oil samples [107]. As illustrated by studies reported in Table 2, MIPs were applied to the selective extraction of OPPs from different matrices such as water samples, aqueous or hydro-organic extracts of vegetables or of soil.…”

Recent advances in the application of capillary electromigration methods for food analysis and Foodomics

“…This method allows the detection of trace levels of trichlorfon, achieving LOD values of 0.16 mg/L, which improved the sensitivity of other methods reported in literature. On the other hand, a dual‐layer solid‐phase extraction based on molecular imprinting technology was proposed in order to enhance the selectivity fot the analysis of pesticide residues in olive oil . This time, organophosphorus and triazine type pesticides were simultaneously determined in a single procedure.…”