Magnetic solid-phase extraction (MSPE), an emerging sample pretreatment technique, has received much attention because of its environment friendliness, rapid separation process, excellent adsorption ...efficiency, and easily automated assay. This paper reviews the nature of MSPE, and the types and preparation of magnetic adsorbents. It also discusses recent application of MSPE to the analysis of trace contaminants in food samples, such as pesticides and veterinary drug residuals, polymer additives, and heavy metals ions. The future development trends of MSPE in food safety analysis are also investigated. High efficiency, low cost, and environmental-friendly food safety detection techniques are expected with the application of MSPE.
•Recent applications of MSPE in food safety analysis are reviewed.•Different preparation strategies for modified magnetic nanoparticles are discussed.•The analysis of various pollutants in food is overviewed.•The possible adsorption mechanisms are discussed.
•The type and damage of biological and chemical contaminants in food are presented.•The structural and functional characteristics of COFs are reviewed.•Recent applications of COFs to the extraction ...and analysis of food contaminants.•The prospects of COFs for food contaminant analysis are discussed.
Food safety issues are a great concern of the international community. Many methods to analyze and detect food contaminants have been widely researched because both biological and chemical contaminants in food can cause severe damage to human health. Several adsorbent materials have been utilized in the complicated procedure of food sample pretreatment. Covalent organic frameworks (COFs) present enormous application potential due to their tailorable skeletons and pores and fascinating features. In this review, recent applications of COF-based adsorbents for the extraction and analysis of food contaminants, including polycyclic aromatic hydrocarbons, biogenic amines, pesticides, endocrine-disrupting chemicals, heavy metal ions, illegal additives, and biotoxins, from complex samples are summarized. Current challenges and future prospects are also discussed.
•Polyimide was used as a self-sacrifice template for fabricating Co@NCSS.•Co@NCSS exhibited excellent catalytic performance as PMS activator towards sulfonamides degradation.•1O2 was the dominant ...oxidative species in SMX degradation by Co@NCSS/PMS.•The decorated Co nanodots acted as the dominant catalytic sites for PMS activation.
Superstructures have attracted attention because of their potential applications in chemistry and materials science. In this work, we report the preparation of a porous 3D superstructure of nitrogen-doped carbon decorated with ultrafine cobalt nanodots (Co@NCSS) derived from the self-assembly of polyimide nanoparticles. Utilizing modified ultra-small cobalt nanodots as main catalytically active sites, and the excellent quality and electron transport efficiency generated by this 3D porous superstructure, Co@NCSS exhibited excellent catalytic performance as a peroxymonosulfate (PMS) activator towards the degradation of several sulfonamides. Based on radical scavenging tests and electron paramagnetic resonance (EPR), singlet oxygen (1O2) was the dominant oxidative species. Furthermore, through the identification of degradation intermediates by HPLC-MS and DFT calculation, the pathway of sulfamethoxazole (SMX) degradation by Co@NCSS/PMS was analyzed. The possible catalytic mechanism of Co@NCSS/PMS for SMX degradation is also proposed in this paper. Co@NCSS has the potential to be an ideal material for removing antibiotics from wastewater.
In recent years, graphene-based magnetic composites have attracted tremendous research interest owing to its exceptional properties, such as huge surface area, large delocalized π-electron system, ...strong magnetic responsiveness, and excellent mechanical/thermal stability. These promising properties together with the ease of processibility and functionalization render graphene-based magnetic composites to be ideal adsorbents in magnetic solid-phase extraction. In this review, we outline the state of the art on the preparation approaches for different graphene-based magnetic composites and its application as adsorbents in preconcentrating organic compounds, biological macromolecules, and metal ions. In addition, future research directions of this type of magnetic materials are identified as well.
•Graphene-based magnetic solid-phase extraction (MSPE) was discussed.•The synthesis of different graphene-based magnetic composites (GMC) were reviewed.•Application of GMC as adsorbents for MSPE were summarized.•Future research directions of GMC were identified.
Peracetic acid (PAA) has garnered significant attention as a novel disinfectant owing to its remarkable oxidative capacity and minimal potential to generate byproducts. In this study, we prepared a ...novel catalyst, denoted as cobalt modified nitrogen-doped carbon nanotubes (Co@N-CNTs), and evaluated it for PAA activation. Modification with cobalt nanoparticles (∼4.8 nm) changed the morphology and structure of the carbon nanotubes, and greatly improved their ability to activate PAA. Co@N-CNTs/PAA catalytic system shows outstanding catalytic degradation ability of antiviral drugs. Under neutral conditions, with a dosage of 0.05 g/L Co@N-CNT-9.8 and 0.25 mM PAA, the removal efficiency of acyclovir (ACV) reached 98.3% within a mere 10 min. The primary reactive species responsible for effective pollutant degradation were identified as acetylperoxyl radicals (CH3C(O)OO•) and acetyloxyl radicals (CH3C(O)O•). In addition, density functional theory (DFT) proved that Co nanoparticles, as the main catalytic sites, were more likely to adsorb PAA and transfer more electrons than N-doped graphene. This study explored the feasibility of PAA degradation of antiviral drugs in sewage, and provided new insights for the application of heterogeneous catalytic PAA in environmental remediation.
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•Cobalt modified nitrogen-doped carbon nanotubes (Co@N-CNTs) was synthesized as a novel catalyst.•The modification of cobalt nanoparticles greatly improved the ability of catalyst to activate PAA.•Co@N-CNTs/PAA catalytic system shows outstanding catalytic degradation ability of antiviral drugs.•CH3C(O)OO• and CH3C(O)O• were identified as the primary species in Co@N-CNTs/PAA system.
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•Novel COF materials with high crystallinity and high specific surface area were used as precursors for cobalt nanoparticle supports.•The efficiency of SMZ degradation reached 92.4 % ...within 10 min by Co@COF/PMS.•1O2 was the dominant active species for SMZ degradation.•Co0, pyridine N, and graphitic N were the active sites of Co@COF.
In this work, new covalent organic framework (COF) materials with high crystallinity and large specific surface areas were used as cobalt-loaded supports. Cobalt nanoparticle-embedded nitrogen-doped carbon porous catalysts (Co@COF) were obtained by high-temperature pyrolysis of the COF materials and cobalt salts. With multiple active sites (Co0, pyridine N, and graphitic N), Co@COF exhibited superior catalytic properties for peroxymonosulfate (PMS) activation toward the degradation of sulfamerazine (SMZ). The efficiency of SMZ degradation reached 92.4 % within 10 min and the total organic carbon (TOC) removal rate reached 70.3 % within 30 min. Using radical quenching experiments and electron paramagnetic resonance (EPR) analysis, sulfate radicals (SO4•−), hydroxyl radicals (•OH), and singlet oxygen (1O2) were identified in this system, while 1O2 was the dominant active species for SMZ removal. The degradation intermediates of SMZ in Co@COF/PMS were monitored by high performance liquid chromatography–time of flight mass spectrometry (HPLC–TOFMS).
A magnetic covalent organic framework (Fe
3
O
4
@COF) with core–shell structure was fabricated at room temperature and used as an adsorbent for magnetic solid-phase extraction of polar ...endocrine-disrupting phenols (4-n-nonylphenol, 4-n-octylphenol, bisphenol A and bisphenol AF). The sorbent was characterized by transmission electron microscopy, FTIR, powder X-ray diffraction and other techniques. The main parameters governing the extraction efficiency were optimized. The phenols were quantified by HPLC with fluorometric detection. The method has attractive features such as low limits of detection (0.08–0.21 ng.mL
−1
), wide linear ranges (0.5–1000 ng.mL
−1
), and good repeatability (intra-day: 0.39%–4.99%; inter-day: 1.57%–5.21%). Satisfactory results were obtained when the developed method was applied to determine the four target pollutants in real world drink samples with spiked recoveries over the range of 81.3~118.0%. This indicates that the method is a powerful tool for the enrichment and determination of endocrine-disrupting phenols in drink samples.
Graphical abstract
A magnetite based covalent organic framework (Fe
3
O
4
@COFs) was synthesized with TPAB, TPA and Fe
3
O
4
. It was used for magnetic solid-phase extraction of endocrine-disrupting phenols from plastic-packaged tea drink samples coupled with liquid chromatography (LC) for determination.
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•A novel carbon-based single-atom cobalt catalyst was fabricated by low-temperature solvothermal treatment.•The kobs of Co-N5/CNT was 1.6 times higher than that of the Co-N4/CNT ...catalyst.•Atomically dispersed Co-N5 sites in the Co-N5/CNT were verified as the active sites.•The electron transfer mechanism was the primary pathway for SMZ degradation in Co-N5/CNT/PMS system.
Carbon-based single-atom cobalt catalysts exhibit high catalytic activity for the removal of novel pollutants in advanced oxidation processes. Here, atomically dispersed Co species with five-coordinated nitrogen atoms on carbon nanotubes (CNT) catalyst (Co-N5/CNT) was successfully fabricated via a low-temperature solvothermal reaction. The obtained Co-N5/CNT catalyst exhibited superior catalytic performance for PMS activation for sulfamerazine degradation. Its apparent rate constant kobs was 1.6 times higher than that of the Co-N4/CNT catalyst with four-coordinated nitrogen atoms prepared by the same method. Electron transfer non-radical mechanism was the main pathway for Co-N5/CNT to activate PMS. Higher single-atom cobalt metal loading (1.39 wt% vs 1.08 wt% in Co-N4/CNT) and significantly enhanced electron transfer ability (0.82 e vs 0.77 e in Co-N4/CNT) were the key factors for its superior catalytic performance. This work demonstrates a novel carbon-based single-atom cobalt catalyst for the removal of novel antibiotic contaminants by activating PMS in environmental catalysis applications.
•3D magnetic Fe3O4 @Co-MONTs yolk-shell microspheres were designed and synthesized.•The new material exhibited good chemical stability and was used as a MSPE material.•The proposed method achieved ...low LODs, wide linearity, and good accuracy for PCBs.•The material was used for the enrichment and determination of PCBs at trace levels.
A new type of three-dimensional, echinus-like magnetic Fe3O4 @ cobalt(Ⅱ)-based metal-organic nanotube (Fe3O4 @ Co-MONT) yolk-shell microspheres, have been designed and synthesized for the first time. Fe3O4 @ Co-MONTs yolk-shell microspheres were characterized by scanning electron micrographs, transmission electron microscopy, Fourier transform infrared spectra, X-ray diffraction, and vibrating sample magnetometry. The feasibility of the new material for use as an absorbent was investigated for magnetic solid phase-extraction (MSPE) of polychlorinated biphenyls (PCBs) from environmental water samples and biological samples. The Plackett-Burman design and Box-Behnken design were used to determine and optimize the extraction parameters influencing the extraction efficiency through response surface methodology. Under the optimized conditions, the developed method showed good linearity within the range of 5–1000ngL−1, low limits of detection (0.31–0.49ngL−1), and good reproducibility (RSD<10%). The proposed method was successfully applied for the analysis of PCBs in real environmental water samples. These results demonstrated that Fe3O4 @ Co-MONTs is a promising adsorbent material for the MSPE of PCBs at trace levels from environmental water samples and biological samples.
The facile fabrication of covalent organic frameworks (COFs) is significant for exploring and promoting their application. In this study, TAPA-TFPB-COFs with flower-shaped morphology, good ...crystallinity, and high surface area was prepared via a facile room-temperature method. The as-synthesized TAPA-TFPB-COFs exhibited great adsorption capacity towards quinolone antibiotics (QAs) and satisfying reusability. Utilizing the TAPA-TFPB-COFs as solid-phase extraction cartridge packing and liquid chromatography-tandem mass spectrometry as detector, a reliable and ultrasensitive method for the assay of QAs was developed. The linearity ranges of QAs extended from 0.5 to 200 ng L−1 with correlation coefficients higher than 0.9974, and the limits of detection varied from 0.02 to 0.11 ng L−1. The intra-day and inter-day precision were lower than 10.8% and 6.7%, respectively. The applicability of the developed method was evaluated through analyzing of tap water, spring water, chicken, and fish samples. The recoveries of QAs in spiked water and food samples varied from 80.0% to 107.6%. The reliability of the developed method was further verified by the accurate detection of QAs in a fish certified reference material.
•TAPA-TFPB-COFs was prepared by a facile room-temperature method.•TAPA-TFPB-COFs exhibited good extraction ability for quinolone antibiotics.•The developed SPE-LC-MS/MS method was reliable and ultrasensitive.•This method was suitable for analysis of quinolone antibiotics in water and meat.
