Magnetic microsphere sorbent on CaCO3 templates: Simple synthesis and efficient extraction of trace carbamate pesticides in fresh produce

Polyaniline-coated kapok fibers for convenient in-syringe solid-phase microextraction and determination of organochlorine and pyrethroid pesticide residues in aqueous samples

Pesticides used in agriculture have low polarity and a tendency to accumulate in fatty tissues, posing potential risks to human health. Effective pre-treatment is crucial due to complex sample matrices and low concentrations of pesticide residues typically encountered in instrument analysis. In this study, polyaniline-coated kapok fiber (PANI-KF) was synthesized successfully using in-situ oxidative polymerization for use as sorbents in in-syringe SPME of pyrethroid pesticides (PYRs) and organochlorine pesticides (OCPs) from aqueous samples. Coating the natural KF with PANI maintained the hollow microtubular structure and fiber morphology while significantly enhancing the extraction efficiency. The extraction process was easily conducted by simply pulling and pushing the syringe plunger. The entire extraction process, utilizing 3 mg of PANI-KF, could be completed in approximately 3 min. Density functional theory results indicated that the adsorption mechanism of PANI-KF towards OCPs and PYRs mainly involved van der Waals interactions, π-π interactions, and weak hydrogen bonding interactions. With the coupling of gas chromatography-mass spectrometry, a quantification method was established that exhibited good linearities (R2 > 0.990), and relative recoveries (87.2-108.5 %). The limits of detection ranged from 0.4 to 2.0 ng mL-1 and the matrix effects were negligible (-12.3-16.4 %). The validated in-syringe SPME-GC-MS method was successfully applied to determine pesticide residues in fruit juices, oral liquids and herbal extract granules with satisfactory accuracy and precision. PANI-KF exhibits remarkable promise as a sorbent for the extraction and enrichment of pesticide residues in aqueous samples, thereby contributing to the advancement of pesticide residue determination methodologies.

Application of novel adsorbents synthesized with polypyrrole in magnetic solid-phase extraction of fungicides from fresh juice and environmental water

In this work, a magnetic adsorption material based on a metal-organic framework (Fe3O4@PPy@MIL-53(Fe)) was designed and prepared, as well as used as an adsorbent for the extraction of fungicides from fresh juice and environmental water. The material was subjected to a series of characterization analyses, which showed that the material has good potential for application as an adsorbent. The main parameters such as adsorbent dosage, adsorption time, elution time, pH value, and elution solvent which could affect the experiment results were optimized. Under optimal conditions, the method exhibited linearity (R2 ≥ 0.9994) in the concentration range 10-1000 µg/L for three triazole fungicides, and LOD value ranged from 2.1 µg/L to 2.9 µg/L. In addition, the established method was applied to real samples of three fruit juices and two ambient waters, and satisfactory recoveries in the range of 78.6%-105.4% and RSDs of ≤ 5.7% were obtained.

Porous organic framework as coating for stir bar sorptive extraction of carbamate pesticides from corn and potato samples

Three porous organic frameworks (POFs) were synthesized by the reaction between phloroglucinol and 1,4-phthalaldehyde, 4,4'-biphenyldialdehyde or tris-(4-formylphenyl) amine; the products are named as POF-a, POF-b and POF-c, respectively. They were used to prepare POFs coated stir bars respectively for the extraction of four carbamate pesticides (CMPs). POF-c coated stir bar exhibited better adsorption performance than POF-a/b coated stir bar and commercial stir bars, probably due to the stronger conjugated structure and hydrophobicity of POF-c, and resultant hydrophobic, π-π and hydrogen bonding interactions between them. The adsorption mechanism for target CMPs was verified by characterization techniques and molecular dynamics simulation. A method of POF-c coated stir bar sorptive extraction-high performance liquid chromatography-variable wavelength ultraviolet detector was developed for the analysis of four CMPs in corn and potato samples. Under the optimal conditions, LODs of the method were between 0.017 and 0.048 μg/L, and the linear range for four CMPs was 0.1/0.2-200 μg/L.

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins, Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.