Phenolic Endocrine Disruptors Research Articles

Green construction of magnetic azo porous organic polymer for highly efficient enrichment and detection of phenolic endocrine disruptors

Porous organic polymers (POPs) are prominent sorbents for effective extraction of endocrine disrupting chemicals (EDCs). However, green and sustainable construction of functional POPs is still challenging. Herein, we developed a magnetic azo POP (Mazo-POP) for the first time using hydroxy-rich natural kaempferol and low-toxic basic fuchsin as monomers through a diazo coupling reaction. The Mazo-POP exhibited excellent extraction capabilities for EDCs with a phenolic structure. Consequently, it was used as a magnetic sorbent for extracting phenolic EDCs from water and fish samples, followed by ultrahigh-performance liquid chromatography-tandem mass spectrometric detection. The Mazo-POP based analytical method afforded a good linearity of 0.06–100 ng mL−1 and 0.3–500 ng g−1 for water and fish samples respectively, with detection limits (S/N = 3) of 0.02–0.5 ng mL−1 and 0.1–1.5 ng g−1, respectively. The method recovery was from 85.2% to 109% and relative standard deviation was less 5.3%. Moreover, the effective adsorption was mainly contributed by hydrogen bond, π-π interaction, pore filling and hydrophobic interaction. This work not only provides an efficient method for sensitive determination of phenolic EDCs, but also highlights the significance of green preparation of environmentally friendly sorbents for enriching/adsorbing pollutants.

Thermostable Bacterial Laccase: Catalytic Properties and Its Application in Biotransformation of Emerging Pollutants.

Laccases have been predominantly reported in fungi, and primarily, fungal laccases are currently exploited in industrial applications. However, extremophilic bacterial laccases possess immense potential, as they can withstand extreme temperatures, pH, and salt concentrations. In addition, unlike fungal laccases, the production of bacterial laccases is cost-effective. Therefore, bacterial laccases are gaining significant attention for their large-scale applications. Previously, we reported a novel thermostable laccase (LacT) from Brevibacillus agri. Herein, we have confirmed that LacT shares a high sequence similarity with CotA laccase from Bacillus amyloliquefaciens. Peptide mass fingerprinting of LacT was conducted via matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF/MS-MS). Inductively coupled plasma-optical emission spectroscopic (ICP-OES) analysis revealed the presence of ∼3.95 copper ions per protein molecule. Moreover, the secondary and tertiary structure of LacT was studied using circular dichroism (CD) and fluorescence spectroscopy. The absence of notable shifts in CD and fluorescence spectra with an increase in temperature established that LacT remains intact even at elevated temperatures. Analysis of the thermal denaturation profile of LacT by thermogravimetric analysis (TGA) also confirmed its temperature stability. Thereafter, we exploited LacT in its application for the bioremediation of phenolic endocrine disruptors, namely, triclosan, 4,4'-dihydroxybiphenyl, and dienestrol. LacT oxidizes 4,4'-dihydroxybiphenyl and triclosan but no LacT activity was detected with dienestrol. The rate of biotransformation of 4,4'-dihydroxybiphenyl and triclosan increased in the presence of CuSO4 and a redox mediator, ABTS. Transformation of dienestrol was observed only with LacT in the presence of ABTS. This study establishes the application of LacT for the bioremediation of phenolic compounds.

Synthesis of MRGO@ZIF-7-Based Molecular Imprinted Polymer by Surface Polymerization for the Fast and Selective Removal of Phenolic Endocrine-Disrupting Chemicals from Aqueous Environments

In this study, Zn(NO3)2·6H2O was selected as the metal source, and ZIF-7-modified magnetic graphene-based matrix materials (MRGO@ZIF-7) were prepared by in situ growth. ZIF-7 modified magnetic graphene-based molecular imprinting complexes (MRGO@ZIF7-MIP) were successfully synthesized by a surface molecular imprinting technique using bisphenol A (BPA) as the template molecule. The obtained experimental materials were characterized by X-ray diffraction (XRD), Brunner–Emmet–Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS). The proper adsorption and selective recognition ability of the MRGO@ZIF7-MIP were studied by an equilibrium adsorption method. The obtained MRGO@ZIF7-MIP showed significant molecular recognition of bisphenol A (BPA) and good selectivity and reproducibility for BPA in different aqueous environments such as drinking water, river water, and lake water. These properties make this material potentially applicable for the efficient removal of phenolic endocrine disruptors in real water environments.

ZIF-8@Rhodamine B as a Self-Reporting Material for Pollutant Extraction Applications.

Herein, we have evaluated the potential of dye-encapsulation as a simple mechanism to self-report the stability of MOFs for pollutant extraction applications. This enabled the visual detection of material stability issues during the selected applications. As proof-of-concept, the zeolitic imidazolate framework (ZIF-8) material was prepared in aqueous medium and at room temperature in the presence of the dye rhodamine B. The total amount of loaded rhodamine B was determined using UV-vis spectrophotometry. The prepared dye-encapsulated ZIF-8 showed a comparable extraction performance with bare ZIF-8 for the removal of hydrophobic endocrine-disrupting phenols, such as 4-tert-octylphenol and 4-nonylphenol, and improved the extraction performance of more hydrophilic endocrine disruptors, such as bisphenol A and 4-tert-butylphenol.

Construction of ionic liquid-filled silica shell microcapsules based on emulsion template and evaluation of their adsorption properties toward 3,4,5-trichlorophenol after various surface functionalization

The development of environmentally friendly and efficient methods for the removal of Phenolic endocrine disruptors (PEDs) from aqueous is essential to protect the environment and human health. In this work, sol–gel method and emulsion template approach were combined and applied to construct 1-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid-filled silica-shell microcapsules (SiO2@IL). And amino, halogen and long-chain alkanes surface-functionalized silica-shell encapsulated ionic liquid microcapsules (SiO2-NH2@IL, SiO2-Cl@IL, and SiO2-C16@IL) were successfully formulated by silica layer modification techniques. The microcapsules have homogeneous dimensions, about 1 µm, and high loading, about 92 wt% of ILs. Four microcapsules showed high adsorption properties and excellent regeneration performance for removing 3,4,5-trichlorophenol (3,4,5-TCP), which benefited from the excellent performance of [BMIM]PF6 on the extraction of 3,4,5-TCP and the enhanced hydrophobic and electrostatic effects of the surface modified microcapsules. The maximum adsorption capacity of SiO2@IL, SiO2-NH2@IL, SiO2-Cl@IL and SiO2-C16@IL calculated from the Langmuir model was 1047, 1207, 1108 and 1145 mg g−1 at 25 °C, respectively. The main factors affecting the extraction performance were the hydrophobicity and steric hindrance of [BMIM]PF6. After three regeneration cycles, the adsorption capacity and desorption efficiency of microcapsules were still above 90 %. The functionalization of the shell layer enhances the hydrophobic and electrostatic effects, which is conducive to the adsorption process, and provides some theoretical and data support for the subsequent construction of ionic liquid encapsulation materials for chlorophenol removal.

Three-dimensional flower-like SnS2 materials for dispersive solid-phase extraction of endocrine-disrupting phenols.

In this study, three-dimensional flower-like tin disulfide materials were prepared, and a highly efficient dispersive solid-phase extraction method was developed using the obtained three-dimensional tin disulfide adsorbents for the preconcentration and determination of six endocrine-disrupting phenols in combination with high-performance liquid chromatography-ultraviolet detection. Several important experimental parameters influencing extraction efficiency were investigated, including the amount of adsorbent, ultrasound time, sample solution pH, sample volume, type of elution solvent, desorption time, and the number of desorption times. Under the optimized experimental conditions, the developed method showed good linearity with the determination coefficients of 0.993-0.998 in the linear range of 0.5-400ng/ml and low limits of detection in the range of 0.15-1.0ng/ml, as well as satisfactory intra-day and inter-day precisions with relative standard deviations of 0.1-9.8%. Finally, the proposed method was successfully applied for the enrichment and determination of trace endocrine-disrupting phenols in milk, tea beverage, and plastic bottled water samples, and acceptable recoveries were obtained from 70.1% to 119.1% under four different spiked concentration levels. The results showed that the three-dimensional tin disulfide materials had great potential for the extraction of endocrine-disrupting phenols contaminants in environmental and food samples.

Application progress of covalent organic framework materials in extraction of toxic and harmful substances

有毒有害物质的排放以及其可能具有的持久性和生物蓄积性,时刻危及人体健康甚至生命。因此,对环境、饮用水、食物和日用品中的有毒有害物质进行分析检测十分重要。对于复杂样品中痕量有毒有害物质的分析,样品预处理是一个至关重要的环节,直接影响分析方法的灵敏度和准确性。在有毒有害物质萃取中广泛应用的预处理技术包括固相萃取(SPE)、固相微萃取(SPME)、分散固相萃取(DSPE)、磁固相萃取(MSPE)等。在上述样品预处理技术中,吸附剂材料是最为核心的部分,它决定了预处理方法的选择性和效率。近年来,共价有机骨架(covalent organic frameworks, COFs)材料因其具有形貌结构多样、比表面积高、孔径可调、稳定性良好等优点,在样品预处理领域受到越来越多的关注。然而,COFs材料在萃取有毒有害物质方面的应用仍存在一些问题需要解决:(1)多数COFs是高度疏水的,这限制了它们在水基样品中的分散性,导致不良的萃取效果;(2)COFs材料主要依靠π-π堆积等相互作用对疏水性目标物进行高效萃取,但不利于极性有毒有害物质的萃取;(3)多数COFs材料存在合成工艺复杂、生产成本高、量产困难等问题。该文对近几年COFs材料在有毒有害物质萃取过程中的研究进展进行了总结和评述。最后,展望了COFs材料在该领域中的应用前景,为进一步研究基于COFs材料的预处理技术提供了参考。

Migration study of phenolic endocrine disruptors from pacifiers to saliva simulant by solid phase microextraction with amino-functionalized microporous organic network coated fiber

Parabens, bisphenols, and triclosan are used in many baby products, including pacifiers. However, the migration through oral saliva will result in a potential health risk. The present study proposes a sensitive and simple method for the analysis of these chemicals in saliva simulants by solid phase microextraction (SPME) with amino-functionalized microporous organic network (MON-NH2) coated fiber. The MON-NH2 showed an excellent adsorption ability for phenolic compounds. The adsorption isotherm fitted the Langmuir isotherm model and the adsorption kinetics followed the pseudo second-order model. The developed SPME method exhibited wide linear ranges (0.005–500 µg/L), good linearity, low limits of quantitation (0.005 µg/L), great recoveries (87.0–112.5 %), and excellent precision (RSD < 8.3 % for intra-day and RSD < 13.7 % for inter-day). Mathematical models based on Fick’s second law were applied to predict migration from pacifiers into saliva simulants and a good fit between theoretical and experimental migration results was found. The daily exposure assessment results indicated that these chemicals in pacifiers do not pose unacceptable health risks to infants. However, exposure risks still should be monitored and appropriate precautions are still needed to protect infants from exposure to these chemicals.

Peanut shells-derived biochars as adsorbents for the pipette-tip solid-phase extraction of endocrine-disrupting phenols in water, milk and beverage

In the present work, a type of biochar materials derived from carbonizing peanut shells were obtained and employed as the adsorbents of pipette-tip solid-phase extraction (PT-SPE) for the enrichment and determination of six endocrine-disrupting phenols (EDPs) in combination with high-performance liquid chromatography equipped with ultraviolet detector (HPLC-UV). Abundant aliphatic and aromatic carbon structures and functional groups from polar heteroatoms (N, O, S) were distributed in the low-cost and eco-friendly peanut shells-derived biochar materials and were favorable for the enrichment of target EDPs. Moreover, the theoretical calculation based on density functional theory (DFT) proved that the effective enrichment of EDPs in aqueous samples benefited from the effective adsorption on the peanut shells-derived biochar materials. The experimental factors influencing the extraction efficiency were investigated, including adsorbent amount, aspirating/dispensing cycles, the type of elution solvent and elution times, salt addition, sample solution pH and type and volume of washing solvent. Under the optimal conditions, the proposed PT-SPE method exhibited good linear relationship (R2 > 0.993) in the range of 0.5–400 µg/L and low limits of detections (LODs) from 0.25 to 2.5 µg/L, as well as good precision and accuracy with relative standard deviations (RSDs) of 0.3%–13.2% and recoveries of 83.5%–117.1%. Finally, the biochars-based miniaturized pretreatment method was employed for the determination of six EDPs in bottled water, milk, tea beverage and disposal plastic bag soaked solution with recoveries from 77.5% to 116.5%.

Miniaturized 3D printed solid-phase extraction cartridges with integrated porous frits

Here we have studied the effect of the thickness and printing orientation using PolyJet 3D printing to fabricate single-material cartridges with built-in porous frits enabling solid-phase extraction (SPE) by packing commercial sorbents. This is achieved by tuning the degree of interpenetration of the building material and the water-soluble support material used in PolyJet 3D printing by modifying the orientation of the print head respective to the frit. SPE cartridges printed at an orientation of 30° with a 150 μm thick integrated frit were selected for the SPE experiments in a compromise between frit permeability to flow and stability to retain commercial sorbents for SPE.The performance of the 3D printed cartridges was evaluated for the SPE of the endocrine-disrupting phenols 4-tert-octylphenol (4-tOP) and 4-nonylphenol (4-NP), comparing three commercial SPE sorbents (Evolute Express ABN, Bond Elut PPL, and Silica-C18). The best overall extraction performance was obtained using Silica-C18, and the main extraction parameters were optimized. Detection limits of 0.3 μg L−1 for 4-tOP and 1.1 μg L−1 for 4-NP were achieved using HPLC-DAD for analyte separation and quantification. Enrichment factors of 30.1 (4-tOP) and 16.2 (4-NP) were obtained under the selected conditions. The developed method was applied to water and milk powder samples obtaining satisfactory recoveries ranging from 97% to 103%. These results demonstrate the suitability of PolyJet 3D printing for the fabrication of miniaturized cartridges with integrated frits for SPE applications.

Electrochemical identification of hazardous phenols and their complex mixtures in real samples using unmodified screen-printed electrodes

The electrochemical behavior of some of the most relevant endocrine-disrupting phenols using unmodified carbon screen-printed electrodes (SPEs) is described for the first time. Experiments were made to assess the electrochemical behavior of phenol (PHOH), pentachlorophenol (PCP), 4-tert octylphenol (OP) and bisphenol A (BPA) and their determination in the most favorable conditions, using voltammetric methods such as cyclic voltammetry (CV), linear sweep voltammetry (LSV) and square wave voltammetry (SWV) in Britton Robinson (BR) buffer. Further, the usefulness of the electrochemical approach was validated with real samples from a local river and was compared to commercial phenols test kit, which is commonly used for on-site screening in industrial streams and wastewaters. Finally, the approach was compared with a lab-bench standard method using real samples, i.e., high-performance liquid chromatography with a photodiode array detector (HPLC-DAD).

New low viscous hydrophobic deep eutectic solvents for the ultrasound-assisted dispersive liquid-liquid microextraction of endocrine-disrupting phenols in water, milk and beverage

In the present work, several new hydrophobic deep eutectic solvents (HDESs) were prepared with quaternary ammonium salts as hydrogen bond acceptors (HBAs) and salicylate esters as hydrogen bond donors (HBDs). Then, the obtained HDESs were used as extraction solvents to establish an ultrasound-assisted dispersive liquid-liquid microextraction method combined with high-performance liquid chromatography-ultraviolet detection technique for the determination of four endocrine-disrupting phenols (EDPs) compounds. One of the obtained HDESs composed of tetrabutylammonium chloride (N4444Cl) and methyl salicylate possessed a viscosity of 89.28 mPa•s lower than most reported ionic HDESs (>200 mPa•s), and the low viscous HDES was selected as the optimal extraction solvent. Several key parameters affecting the extraction efficiency were investigated, including the type and volume of HDES, ultrasound time, sample solution pH and salt addition. Under the optimized experimental conditions, the proposed method had good coefficients of determination (R2 > 0.9976) in the linear range of 0.5–400 µg•L−1, the limits of quantification and limits of detection respectively were 0.5–2.5 µg•L−1 and 0.25–1 µg•L−1, and the recoveries were in the range of 81.79–109.82%. Finally, the method was used for the preconcentration and determination of EDPs in different samples, including bottled water, tea beverage and milk.

Ionic liquids filled hybrid capsules by harnessing interfacial imine chemistry of Janus nanosheets stabilized pickering emulsion for removal of chlorophenols

Ionic liquids filled hybrid capsules (C-IL) hold promise as extraction medium to remove phenolic endocrine disruptors (PEDs), which are priority pollutants because of their high persistence and toxicity. Nonetheless, preparation of uniformly sized C-IL has stand out as the major drawback for their use on adsorption applications. In this work, Janus graphene oxide (J-GO) nanosheets stabilized Pickering emulsion incorporated with interfacial imine chemistry were used for synthesis of polymer shell encapsulated 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6), and then as-prepared hybrid capsules (C-IL/W) were considered as a novel material for 3,4,5-trichlorophenol (3,4,5-TCP) capture. Uniformly sized C-IL/W (180 μm in diameter) had high IL content of 90 wt%, and its shell thickness from quick interfacial imine chemistry in situ is about 2.0 to 2.5 μm. Benefiting from the strong hydrogen bonding and π-π conjugation of the two aromatic rings with loaded [BMIM]PF6, the maximum adsorption capacity calculated from Langmuir model was 6775 mg g−1 at 25 °C for 3,4,5-TCP. Through the principal component analysis (PCA), the facts that chlorine substituent such as its number and location posed a significant influence on the PEDs extraction efficiency were confirmed, which followed the order: 2-chlorophenol (2-CP) < 2,6-dichlorophenol (2,6-DCP) < 2,4-dichlorophenol (2,4-DCP) < 3,4,5-TCP. The hydrophobicity and steric hindrance upon [BMIM]PF6 were the main factors affecting the extraction performance. After three regeneration cycles, the adsorption capacity of capsules towards 3,4,5-TCP was 79% of the first cycle, and the desorption efficiency was still above 90%. The results not only demonstrated an important method to design C-IL for PEDs removal, but also suggested the possible mechanism for chlorophenols extraction.

Preparation of a Novel Resin Based Covalent Framework Material and Its Application in the Determination of Phenolic Endocrine Disruptors in Beverages by SPE-HPLC.

A new type of economical covalent organic framework material(COF), namely resin based covalent organic framework material, was prepared by combining resin and covalent organic framework material by hydrothermal synthesis, which was based on the preparation of traditional COF material(TpBD COF). The properties of the material and covalent organic framework material were compared in the way of characterization, and the possible reaction mechanism was analyzed. The solid phase extraction separation (SPE) ability of this material for four kinds of phenolic endocrine disrupting compounds (bisphenol F, bisphenol A, octylphenol and nonylphenol) in beverage samples was investigated. The results showed that the prepared COF materials had abundant internal channels, ordered structure, large specific surface area (TpBD COF: 814.6 m2/g and resin based COF: 623.9 m2/g) and good thermal stability (pyrolysis temperature was 443 °C and 437 °C, respectively). Solid phase extraction experiments demonstrated that the two COF materials as adsorbent of solid phase extraction column had ideal adsorption separation effect and good anti-interference ability, and had strong anti-interference ability. The SPE effect was superior to the traditional solid phase extraction column. The precision RSD of this method was less than 3%. This SPE method had high recovery and could be reused (carbonated beverage: 98.18–102.18% and beverage: 98.52–101.79%), In addition, the recovery of the material did not change significantly in the 50 cycles of solid phase extraction, indicating that the material had good stability and could be reused, which could meet the requirements for the detection and analysis of trace pollutants in environmental samples. The resin based COF material prepared in this study could reduce the cost of monomer uses and provide a possibility for its industrial production. At the same time, as an efficient SPE adsorbent, it also provided a new research scheme for the enrichment of trace phenolic endocrine disruptors in beverage samples.

Bioaccumulation of phenolic endocrine disruptors in the clam Rangia cuneata: Storage in shells and influence of size and sex

This study aimed to investigate the sequestration of phenolic endocrine disrupting compounds (EDCs) such as bisphenol A (BPA), 4-t-octylphenol (4-t-OP), and 4-nonylphenol (4-NP) in the shells of the mature clam Rangia cuneata from the Vistula Lagoon (southern Baltic Sea) and to determine the influence of sex and shell length on bioaccumulation of these contaminants. Even though there is broad interest in EDCs influences on aquatic organisms, these basic parameters are poorly understood, yet necessary for assessing environmental risks for clams. Average proportions of the total body burden (ng/individual) deposited in shells of R. cuneata were more than 70% for BPA and 4-NP and up to 32% for 4-t-OP. These results indicate that shell storage can be an important route for elimination of specific EDCs. Relationships between EDCs concentrations and the size and sex of R. cuneata indicate that females and large individuals experience greater exposures to the adverse effects of these pollutants than males and smaller clams. This effect could have significant impacts on population ecology and ultimately affect the entire ecosystem, in which bivalves play an important role. In the context of using clams to assess water pollution, the co-variation of EDCs concentrations with the size and sex of bivalves could influence the quality of monitoring data, unless accounted for in sampling design and data analysis.

Morphology-tunable hollow Mn2O3 nanostructures: highly efficient electrocatalysts and their electrochemical sensing for phenolic endocrine disruptors via toughening of graphene oxide

In the present study, three-dimensional hollow Mn2O3 polycrystals with various aggregation morphologies including spheres, dumbbells, cubes, and ellipsoids were selectively synthesized by modulating the shape of premade MnCO3 precursors with different manganese sources. Structural and electrochemical analyses demonstrated that the ellipsoidal Mn2O3 hollow structures had a higher specific surface area, wider pore diameter, and superior electron-transfer reactivity, thus, they exhibited greater electrocatalytic activity toward the oxidation of two phenolic endocrine disruptors, i.e., o-phenylphenol (OPP) and butylparaben (BP). In addition, the electro-oxidation of hollow Mn2O3 ellipsoids for OPP and BP was further enhanced when they were physically wrapped with graphene oxide (GO). This remarkable property is attributable to the dramatical increase of active sites and surface-chemisorbed oxygen species in these unique nanostructures. Highlights are presented for the simultaneous determination of OPP and BP within wide linear ranges of 0.002-20 and 0.003-24 μM, with low detection limits of 0.63 and 0.88 nM, respectively. Our findings not only offer a novel morphology-controllable synthesis strategy to better understand the morphology impact on the electrochemical performances of Mn2O3, but also represent a facile design of robust, active, and easy-to-obtain catalysts for sensors and other electrocatalytic systems.

Occurrence of Phenolic Endocrine Disruptors in Danube Delta, Romania

In the last decade, the use of chemical compounds with a molecular structure similar to that of BPA has been reported more and more as alternatives to BPA in various industrial products. This comes as a result of banning partial or total use of BPA because of its endocrine disrupting properties. However, bisphenol analogues have been shown to have similar or even greater negative properties than BPA. Thus, particular attention has been given to the risks they have for aquatic systems and human health. In this context, the present study aimed to determine the concentration level at which some of the bisphenol analogues (BPS, BPB, BPE, BPC and BPE), BPA and its major metabolite, 4-HAP, are found in surface waters. For this purpose, 11 sampling points were established in the geographical area of the Danube Delta. Among the seven targeted pollutants, only four were detected in the analyzed samples. 4-HAP metabolite was the most abundant compound in the analyzed samples, with concentrations ranging from 3.56 to 30.9 ng/L. BPA concentrations were, in most cases approximately three times lower than those determined for 4-HAP. The next bisphenol analog after 4-HAP, in the decreasing order of concentrations, was BPE, for which the concentration level ranged between LOQ and 12.4 ng/L. Lowest concentrations were detected for BPS, with a maximum level of 1.96 ng/L.

Orthogonal array design optimisation of an in situ ionic liquid dispersive liquid–liquid microextraction for the detection of phenol and endocrine-disrupting phenols in aqueous samples

In this paper, a dispersive liquid–liquid microextraction (DLLME) based on the application of in situ ionic liquids (in situ ionic liquid DLLME) was developed for preconcentration and determination of trace amount of phenol and endocrine-disrupting phenols in aqueous samples. The experimental parameters of an in situ ionic liquid DLLME method were investigated and optimised using an orthogonal array design. Several factors affecting extraction efficiency, including percentage concentration of the ionic liquid, the ratio of ionic liquid to the ion exchanger, extraction time as well as centrifugation time, were investigated and optimised. Under the optimal conditions, percentage concentration of the ionic liquid of 5%, the ratio of ionic liquid to the ion exchanger of 1–2, the extraction time of 5 min and centrifugation time of 1 min, the method affords satisfactory recoveries in the range of 99–100%. Consistent repeatability (RSD ≤ 5%) with satisfactory linearity (0.9993 ≥ r2 ≤ 0.9999) of results illustrated a good performance of the present method. The method was applied to the determination of endocrine-disrupting phenols in real seawater samples. The relative recovery of spiked, natural seawater samples was higher than 97%.

A core-shell structured magnetic covalent organic framework (type Fe3O4@COF) as a sorbent for solid-phase extraction of endocrine-disrupting phenols prior to their quantitation by HPLC.

A magnetic covalent organic framework (Fe3O4@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 (0.08-0.21ng.mL-1), wide linear ranges (0.5-1000ng.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 (Fe3O4@COFs) was synthesized with TPAB, TPA and Fe3O4. 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.

Spherical covalent organic frameworks as advanced adsorbents for preconcentration and separation of phenolic endocrine disruptors, followed by high performance liquid chromatography.

As a promising generation of porous micro-materials, covalent organic frameworks (COFs) have great potentials for applications in separation and adsorption. In the present study, an advanced food-safety inspection method involving COFs as the adsorbents of solid phase extraction (SPE) is proposed for sensitive and accurate determination of target hazardous substances. Typical spherical TpBD COFs with large surface area and superior chemical stability were utilized as adsorbents for the preconcentration of phenolic endocrine disruptors (PEDs), followed by high performance liquid chromatography (HPLC) analysis. The well-prepared TpBD COFs were encapsulated in SPE cartridges and applied in food research, namely, for the separation and enrichment of four target endocrine disruptors in food samples. The possible factors influencing the SPE performance including the composition of the sample solvent, sample solution pH, sample flow rate, composition of the eluent, and the volume of the eluent were investigated and optimized. Due to the porous architecture and superior surface area of spherical TpBD, the enrichment of analytes via a COF-filled SPE column gave extremely low detection limits of 0.056–0.123 μg L−1 along with a wide linear range of 0.5–100 μg L−1 for all the analytes. Nine parallel determinations of the mixed standard with a concentration of 10 μg L−1 produced the relative standard deviations of 2.23–3.08%, indicating the excellent repeatability of the COF-SPE assay. This study can open up a new route for the employment of COFs as efficient SPE adsorbents for the enrichment and quantification of trace/ultra-trace hazardous materials in complex food samples.