Facile room-temperature synthesis of magnetic covalent organic framework nanoflowers for efficient MSPE and detection of avermectins.

Room-temperature synthesis of magnetic thiophene-based covalent organic frameworks for derivatization-assisted GC–MS analysis of estrogens in environmental water

Magnetic porous carbon material derived from imine-linked covalent organic frameworks for magnetic solid phase extraction of trace chlorine-containing herbicides in soil

Parabens are a class of antimicrobial preservatives that are widely used in cosmetics, pharmaceuticals, and food products because of their ease of production, antimicrobial effect, and low price. The widespread use of these parabens, poses potential risks to human health. Therefore, it is necessary to establish a simple and rapid method for the detection of parabens. The large number of substrate interferences in complex samples is an important factor affecting the sensitivity of analytical methods. Magnetic solid-phase extraction (MSPE) has received much attention because of its advantages of easy operation, short extraction time, small sample amount, low cost, and environmental friendliness. Covalent organic frameworks (COFs) with high crystallinity, high specific surface area, adjustable pore size, regular porosity, as well as high chemical and thermal stability are now widely used in separation and analysis. Therefore, a sample pretreatment method combining MSPE and COF for the analysis of parabens in complex matrices is very promising. A magnetic covalent organic framework, Fe3O4@TbBd, was successfully synthesized by the Schiff base reaction of 1,3,5-triformylbenzene (Tb) and benzidine (Bd) at room temperature using Fe3O4 nanoparticles as magnetic cores. Characterization by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) measurements, etc. revealed that the magnetic COF has high magnetic responsiveness, as well as good thermal and chemical stability, which make it an ideal adsorbent for the MSPE of parabens. Some factors related to the extraction efficiency, including the amount of adsorbent, extraction time, pH, desorption solvent, desorption time, and number of desorption were systematically investigated. A method involving MSPE and high performance liquid chromatography-ultraviolet detection (HPLC-UV) based on the Fe3O4@TbBd was developed for the determination of four parabens (ethylparaben, propylparaben, butylparaben, and benzylparaben) in environmental water samples. Under the optimal extraction conditions, the method showed good linearities. The limits of detection and limits of quantification were 0.2-0.4 μg/L and 0.7-1.4 μg/L for the four analytes, respectively. The recoveries at three spiked levels were in the range of 86.1%-110.8% with intra-day and inter-day RSDs of less than 5.5% and 4.9%, respectively. The method was successfully applied to the determination of parabens in East Lake water, Yangtze water, and domestic wastewater. Ethyl paraben and propyl paraben were detected in domestic wastewater at the levels of 1.8 μg/L and 0.4 μg/L, respectively. The recoveries of the parabens at different spiked levels ranged from 80.7% to 117.5%, with RSDs of 0.2%-8.8%. The method has good potential for the determination of parabens in environmental water samples because of its operational simplicity, short extraction time, high sensitivity, and environmental friendliness.

痕量污染物因其在环境中的微量存在和基质的复杂性,难以直接通过仪器进行检测,对人类的健康构成潜在威胁。磁性固相萃取(MSPE)技术因具有操作简单、成本低廉、富集效率高等优势,在样品前处理领域一直备受关注。磁性固相萃取的研究聚焦于磁性材料的功能化,近年来研究者深入探索了磁性材料的功能化途径,将多种新兴材料引入磁性材料的修饰,有效拓展了磁性功能化材料的性能和应用领域。其中,磁性共价有机骨架材料(MCOFs)是一种具有代表性的材料,不仅具有比表面积大、稳定性高的特点,还兼具磁性材料的快速分离特性;可通过氢键作用、疏水作用、π-π共轭作用实现对目标物的快速、高效富集。本文重点综述了MCOFs的种类、合成方法及其在富集检测农药、内分泌干扰物(EDCs)及药物和个人护理产品(PPCPs)中的应用,并对该领域未来研究的发展方向进行了展望。

Perfluorinated compounds (PFCs) are widely used in textiles, fire protection, metal electroplating, and semiconductor production owing to their hydrophobic and oil-repellent characteristics. However, they are also persistent organic pollutants. The uncontrolled discharge of PFCs into the environment has led to serious global pollution. PFCs pose severe reproductive, neural, immune, and other threats to human health by accumulating through the food chain. Thus, the development and application of high-performance extraction materials has become a research hotspot in efforts to achieve the accurate detection of trace PFCs in environmental waters. Most traditional PFC adsorbents present a number of disadvantages, such as low adsorption selectivity, slow diffusion, and poor reusability. Covalent organic frameworks (COFs) are crystalline polymers with ordered porous structures, large specific surface areas, and high chemical and thermal stability. These frameworks can easily be functionalized for the desired purpose. In this paper, spherical amino-functionalized COFs (denoted COF-NH2) were fabricated via a two-step method to effectively enrich/remove PFCs from water. First, vinyl covalent organic framework (Vinyl COF) was synthesized at room temperature using 1,4-diradical-2,5-divinylbenzene (Dva) and 1,3,5-tris(4-aminophenyl)benzene (Tab) as building blocks. Then, thioether-bridged aromatic amine-functionalized spherical COF-NH2 was synthesized through a thiol-alkenyl click reaction using 4-aminothiophenol as the functional monomer. COF-NH2 showed good dispersion in water owing to its abundant amino groups, forming multiple hydrogen bonds with the F atoms of PFCs. The synergistic hydrophobic interactions between the organic skeleton of the COF and alkyl carbon chains of the PFCs led to enhanced adsorption efficiency. The produced Vinyl COF and COF-NH2 were characterized by Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and Brunner-Emmet-Teller (BET) measurements. The results confirmed that spherical COF-NH2 materials with a homogeneous size distribution were successfully fabricated. The obtained COF-NH2 microspheres had a diameter of approximately 500 nm and exhibited high thermal stability as well as a large specific surface area and pore volume. The adsorption kinetics, isotherm adsorption models, pH effects, and regeneration properties of COF-NH2 were also investigated, and the results indicated that the adsorption of PFCs by COF-NH2 conformed to the pseudo-second-order kinetic and Langmuir isotherm adsorption models. The obtained COF-NH2 microspheres can be applied over a wide pH range, and the best adsorption effect was achieved in neutral and alkaline environments. After five cycles of regeneration and reuse, the COF-NH2 microspheres retained their good adsorption efficiency for PFCs. The adsorption mechanism was mainly attributed to the synergistic effect of hydrogen bonding and hydrophobic interactions between COF-NH2 and the PFCs. The extraction efficiencies of the microspheres toward five PFCs (perfluorobutyric acid, perfluorovaleric acid, perfluorohexanoic acid, perfluorooctanoic acid, and perfluorononanoic acid) in tap and Pearl River water samples were between 91.76% and 98.59%, with relative standard deviations (RSDs) (n=3) varying from 0.82% to 3.8%; these findings indicate that the obtained COF-NH2 is promising for the extraction of PFCs from complex water samples. Given their uniform size distribution, high thermal stability, good adsorption performance, and reusability, the novel spherical COF-NH2 materials developed in this study may be used as solid-phase extraction materials or filled into liquid chromatographic columns for the enrichment, separation, and detection of PFCs in complex samples.

Phenolic endocrine-disrupting chemicals (EDCs) are widespread and easily ingested through the food chain. They pose a serious threat to human health. Magnetic solid-phase extraction (MSPE) is an effective sample pre-treatment technology to determine traces of phenolic EDCs. Magnetic covalent organic framework (COF) (Fe3 O4 @COF) nanospheres were prepared and characterized. The efficient and selective extraction of phenolic EDCs relies on a large specific surface and the inherent porosity of COFs and hydrogen bonding, π-π, and hydrophobic interactions between COF shells and phenolic EDCs. Under optimal conditions, the proposed magnetic solid-phase extraction-high-performance liquid chromatography-ultra violet (MSPE-HPLC-UV) based on the metallic covalent organic framework method for phenolic EDCs shows good linearities (0.002-6 μg mL-1 ), with R2 of 0.995 or higher, and low limits of detection (6-1.200 ng mL-1 ). Magnetic covalent organic frameworks (Fe3 O4 @COFs) with good MSPE performance for phenolic EDCs were synthesized by the solvothermal method. The magnetic covalent organic framework-based MSPE-HPLC-UV method was applied successfully to determine phenolic EDCs in beverage and water samples with satisfactory recoveries (90.200%-123%) and relative standard deviations (2.100%-12.100%). © 2023 Society of Chemical Industry.

Fungicides can lead to soil and plant diseases after long-term enrichment in the environment; they can also penetrate deeper into the soil and groundwater by rainwater or irrigation, threatening the water environment and human health. Therefore, it is crucial to develop a simple, rapid, efficient, and sensitive analytical method for the detection of fungicides in the water environment. Sample pretreatment is important for the extraction and enrichment of pollutants from environmental water. Magnetic solid phase extraction (MSPE) is a new sample pretreatment method, which uses magnetic materials as adsorbents dispersed in solution, and rapid separation can be achieved by the aid of external magnets. Because of its advantages of short analytical time, less organic solvent consumption, and easy separation of adsorbents, MSPE has attracted much attention. The key to MSPE is the preparation of highly selective magnetic adsorbents. Covalent organic frameworks have the advantages of large surface area, good chemical and thermal stability, tunable porous structure, low density, and easy functionalization, all of which are ideal for adsorbing fungicides. The concentration of fungicides in environmental water is low. Ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has high sensitivity and high selectivity, which is suitable for the analysis of fungicides. In this work, a magnetic covalent organic framework Fe3O4@TpBD was prepared by an in situ method, as the MSPE sorbent material to enrich of benzimidazole fungicides (thiabendazole, carbendazim, fuberidazole) and organic sulfur fungicide (isoprothiolane) in environmental water. An extraction method based on π-π conjugation, hydrogen bonding, and electrostatic interaction between Fe3O4@TpBD and the fungicides, in combination with UHPLC-MS/MS, was developed for the determination of four trace fungicides in water. Transmission electron microscopy (TEM), X-ray diffractometry (XRD), and Fourier transform-infrared spectroscopy (FT-IR) were performed to confirm the successful synthesis of Fe3O4@TpBD and to characterize this material. A series of experiments were carried out to decide the optimal extraction conditions, i. e., the magnetic ratio and dosage of Fe3O4@TpBD, pH of the water sample, adsorption time, type and volume of the eluent, elution time, and salinity. Gradient elution was carried out with methanol-water as the mobile phase. The target analytes were separated on an ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), and multiple reaction monitoring (MRM) was conducted in the positive electrospray ionization mode. The ion source temperature and ion source voltage were set to 500 ℃ and 5 kV, respectively. The analytical method was established under the optimized extraction conditions. The four fungicides showed good linearity in the range of 3-1200 ng/L, with linear correlation coefficients greater than 0.998. The limits of detection (LODs) and limits of quantification (LOQs) of this developed method were 0.06-0.28 ng/L and 0.20-0.92 ng/L, respectively. Recovery tests were performed at three spiked levels of 15, 150, and 600 ng/L, with relative standard deviations of 2.8% to 10.0% (intra-day) and 4.4% to 15.7% (inter-day). The accuracy of the established analytical method was investigated by using it to test real water samples, and satisfactory recoveries for the four analytes were achieved within 77.1% to 119.1%. Trace amounts of carbendazim were detected in the reservoir water at 27.5 ng/L. The method has good sensitivity, accuracy, and precision, and the operation process is convenient.

Facile mechanochemistry synthesis of magnetic covalent organic framework composites for efficient extraction of microcystins in lake water samples

蛋白质糖基化作为最重要的翻译后修饰之一,在生物体诸如细胞信号转导、蛋白质翻译调控、免疫应答等诸多生命过程中发挥重要作用。此外,蛋白质的异常糖基化还与肿瘤等疾病的发生发展密切相关,这为以糖蛋白为目标的疾病生物标志物的发现提供了可能。尽管质谱已经成为糖蛋白质组学的重要分析工具,但糖肽的低丰度和低电离效率使得其直接质谱分析仍面临挑战。在糖蛋白质组学研究中,从复杂的生物样品中富集糖蛋白和糖肽是重要的环节。磁性固相萃取(MSPE)是一种操作简单、成本低和萃取效率高的样品预处理方法。在磁性固相萃取中,磁性吸附剂是影响萃取效果的关键,将功能化磁性纳米材料作为吸附剂进行糖蛋白质组学研究已经得到广泛应用。该文综述了糖分子、离子液体、凝集素、硼酸亲和配体、金属有机框架、共价有机骨架等功能化磁性纳米材料的制备及其在糖蛋白及糖肽富集中的应用。上述功能化磁性纳米材料具有高比表面积、大量作用位点等特点,其富集机理包括亲水相互作用色谱、凝集素亲和作用色谱、硼酸化学法和肼化学法等,主要应用于血清、血浆、细胞、组织、唾液等样品的糖蛋白和糖肽的富集。该文引用了近十年来发表的约90篇源于科学引文索引(SCI)与中文核心期刊的相关论文,并于文末对磁性纳米材料在糖蛋白和糖肽富集领域的发展趋势进行了展望。

Facile fabrication of magnetic urea-based covalent organic framework for selective and efficient solid-phase extraction of parabens in soft drinks and skin toners.

Facile synthesis of porous covalent organic frameworks for the effective extraction of nitroaromatic compounds from water samples

Sol-gel processing of a covalent organic framework for the generation of hierarchically porous monolithic adsorbents

Molecularly imprinted polymers-coated magnetic covalent organic frameworks for efficient solid-phase extraction of sulfonamides in fish

Electroactive covalent organic frameworks: a new choice for organic electronics

Aptamer-functionalized magnetic covalent organic frameworks for rapid extraction and LC-MS/MS quantification of gentamicin in milk.