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

Abstract

The increasing use of pesticides in agriculture causes environmental issues and possible serious health risks to humans and animals. Their determination at trace concentrations in vegetable oils constitutes a significant analytical challenge. Therefore, their analysis often requires both an extraction and a purification step prior to separation with liquid chromatography (LC) and mass spectrometry (MS) detection. This work aimed at developing sorbents that are able to selectively extract from vegetable oil samples several organophosphorus (OPs) pesticides presenting a wide range of physico-chemical properties. Therefore, different conditions were screened to prepare molecularly imprinted polymers (MIPs) by a non-covalent approach. The selectivity of the resulting polymers was evaluated by studying the OPs retention in pure media on both MIPs and non-imprinted polymers (NIP) used as control. The most promising MIP sorbent was obtained using monocrotophos (MCP) as the template, methacrylic acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker with a molar ratio of 1/4/20 respectively. The repeatability of the extraction procedure and of the synthesis procedure was demonstrated in pure media. The capacity of this MIP was 1mg/g for malathion. This MIP was also able to selectively extract three OPs from almond oil by applying the optimized SPE procedure. Recoveries were between 73 and 99% with SD values between 4 and 6% in this oil sample. The calculated LOQs (between 0.3 and 2μg/kg) in almond seeds with a SD between 0.1 and 0.4μg/kg were lower than the Maximum Residue Levels (MRLs) established for the corresponding compounds in almond seed.

Development and application of water-compatible molecularly imprinted polymers for the selective extraction of carbamazepine from environmental waters

“…The breakdown point of the curve, corresponding to the maximum amount of CBZ that can be retained on MIP with a constant recovery, was estimated to be close to 15 µg of CBZ for 55 mg of MIP, which corresponds to a capacity of 0.27 mg g -1 or 1.15 µmole g -1 of MIP. This value is in good agreement with those reported in the literature (between 0.2 µmol g -1 and 9 µmol g -1 ) for MIPs synthesized with the same combination of monomer (MAA) and cross linker (EGDMA) and targeted toward different classes of compounds with various physicochemical properties, like pesticides or drugs [29][30][31][32][33]. Moreover, the mean of the recoveries of 75 ± 5% obtained for the extraction of CBZ from the water spiked between 0.02 and 0.6 µg mL -1 also highlights the reliability of the extraction procedure.…”

“…Non-imprinted polymers (NIP 1 to NIP 5), were synthesized following the same procedure as their corresponding MIP except that the template was absent. The five polymers were generated using a ratio 1/4/20,the most common ratio used in the literature [25][26][27][28][29][30][31], between the template, the monomer, and the cross linker. For all the syntheses, the template (1 mmol) and monomer (4 mmol) were first mixed with 1.8 mL of the corresponding porogen in a glass vial the "template-monomer" complex was allowed to form in an ultra-sonication bath for 10 minutes.…”

Polymer sequestrants for biological and environmental applications

“…The extraction capability of the MIP was significantly greater than that of the NIP for seven of the nine OPPs. As expected, the adsorption capacity was higher in the pure media; however, the results provide the basis for optimization of MIP performance in more complex matrices …”

Recent advances and applications of molecularly imprinted polymers in solid‐phase extraction for real sample analysis

“…Almost all MIP adsorbents for food samples were synthesized via non‐covalent imprinting techniques. Moreover, the bulk polymerization is one of the frequently used polymerization methods for preparing MIP particles [23,25,28,83–87]. Garcia et al.…”