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In this work, a magnetic MIL-101(γ-Fe 2 O 3 )/MWCNTs composite derived from iron-based metal-organic frameworks (MIL-101(Fe)) with multi-walled carbon nanotubes (MWCNTs) was successfully synthesized by low-temperature calcination process. The composite was used as adsorbent of magnetic solid-phase extraction (MSPE) for enhanced and rapid enrichment of trace polycyclic aromatic hydrocarbons (PAHs) based on its strong π-π stacking interactions, hydrophobic and cationic-π stacking interactions. The pseudo-second-order kinetic model and Langmuir isotherm model could be applied to better describe the adsorption process. The maximum adsorption capacity for PAHs reached 93.9 mg g -1 . In addition, the conditions of MSPE process were optimized by orthogonal array design (OAD). A MSPE-HPLC-UV method was established for the sensitive detection of PAHs in real water samples and exhibited wide linear range (0.05-1000 µg L -1 ), low detection limits (0.02-0.41 µg L -1 ) and high enrichment factors (44-169) for PAHs. The relative standard deviations (RSD) ranged from 0.8 to 4.0% and 1.2-7.2% for single batch and batch-to-batch, respectively, and the spiked recoveries at two levels of 10 and 50 µg L -1 ranged from 79.6 to 112% with RSD of less than 5.81%. The unique MWCNTs in situ anchor MIL-101(γ-Fe 2 O 3 ) composite with an outstanding PAHs adsorption performance provides a new opportunity and promising application in removal of toxic pollutants., Competing Interests: Declaration of Competing Interest We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted. The work described has not been published before; it is not under consideration for publication anywhere else; and publication has been approved by all co-authors and the responsible authorities at the institute where the work has been carried out., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The analysis of toxic and harmful substances in food has attracted significant attention. In this work, a molecularly imprinted column coupled to gas chromatography-triple quadrupole tandem mass spectrometry method (MIC-GC-MS/MS) method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in takeaway meal boxes was established by comparing the extraction results of 16 PAHs with 5 different sample pretreatment techniques, and the effects of food types and storage conditions on the migration of PAHs was studied by migration test. The conditions of extraction and chromatography-mass spectrometry were optimized. The results showed that the linear ranges were in the wide range of 1-100 ng mL -1 for 16 PAHs, with the correlation coefficients (R) higher than 0.9983; the detection limits (LODs) and the limits of quantification (LOQs) were in the range of 0.08-0.42 μg kg -1 and 0.24-1.26 μg kg -1 , respectively; the spiked recoveries at three levels of 10, 20, 30 μg kg -1 were in the range of 86.2%-107.7% with the relative standard deviation (RSD) less than 7.8%. Therefore, this method had high sensitivity and good reproducibility and was suitable for the determination of 16 PAHs in food contact materials. The migration test of PAHs showed that the migration amount of PAHs in takeaway meal boxes was closely related to food types, and the migration amount was positively correlated with contact temperature and contact time in a certain range., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Graphite phase carbon nitride (g-C 3 N 4 ) incorporating zeolitic imidazolate framework-8 (ZIF-8) nanocomposite (g-C 3 N 4 /ZIF-8) with hierarchical structure was synthesized successfully by simple and rapid in situ growth method at room temperature. The composites were used as an adsorbent of solid-phase extraction (SPE) and the superior adsorptive removal of polycyclic aromatic hydrocarbons (PAHs) for the first time. Under several optimum conditions, the g-C 3 N 4 /ZIF-8-SPE-HPLC-FLD method show low detection limits (0.006-3.41 μg L -1 ) and limit of quantification (0.02-11.3 μg L -1 ), wide linear ranges from 0.02 to 1000 μg L -1 for all compounds, correlation coefficients (r) of more than 0.9968, and satisfying reproducibility (relative standard deviations, RSDs < 4.0% for intra-day, RSDs < 8.3% for inter-day), the spiked recoveries at two levels of 10.0, 50.0 μg L -1 were in the range of 77.4%-114% with the RSDs less than 8.66%. In addition, the g-C 3 N 4 /ZIF-8 nanocomposites demonstrated excellent enrichment ability and extraction efficiency for PAHs compared with commercial adsorbents, which might since there were strong π-π stacking force, hydrophobic interaction, hydrogen bonding, and more adsorption sites compared with other adsorbents. Finally, the g-C 3 N 4 /ZIF-8 based SPE method was combined with high-performance liquid chromatography (HPLC) to detect fifteen PAHs in environmental water samples successfully., Competing Interests: Declaration of Competing Interest We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted. The work described has not been published before; it is not under consideration for publication anywhere else; and publication has been approved by all co-authors and the responsible authorities at the institute where the work has been carried out., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this work, polystyrene grafted hollow layered double hydroxides (NiCo-LDH@PS) were prepared by co-precipitation method using ZIF-67 as template. The obtained NiCo-LDH@PS was served as solid-phase microextraction (SPME) coating, combined with high performance liquid chromatography (HPLC) could rapidly detect seven polycyclic aromatic hydrocarbons (PAHs). The NiCo-LDH@PS-coated SPME fiber reflected enhanced adsorption capacity for seven PAHs (31.0–97.3 mg g−1) and required only 0.3 g L−1of adsorbent under the optimal extraction conditions by orthogonal array design (OAD), which was on account of the inimitable layered structure, the large surface area of the NiCo-LDH, providing more adsorption sites and electrostatic interactions, cation-π force, and a large number of π-π stacking interactions between PS nanospheres and PAHs. The study showed that NiCo-LDH@PS with hollow core-shell structure has great application potential as SPME composite coating in the field of adsorption and separation. • An innovative layered double hydroxides (NiCo-LDH) with hollow porous structures were successfully prepared. • The hierarchical composite was used as solid-phase microextraction (SPME) fiber coating. • The possible adsorption mechanism was systematically verified and explained. • The proposed method provided a new, effective and low-cost method for rapid and superior capture PAHs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as SPME fiber coating. • BTCH-PTA-COF processes large specific surface area, good chemical and thermal stability. • The BTCH-PTA-COF fiber has perfect extraction efficiency for PAHs. • The adsorption mechanism was confirmed by the density functional theory (DFT) calculation. In this study, a durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as fiber coating, which was applied to solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The hydrophobic and π-π packing interactions between BTCH-PTA-COF and PAHs were confirmed by contact angle experiments and Van der Waals surface electrostatic potential analysis. Further, large specific surface area, good chemical and thermal stability have positive promoting effect on extraction. The method of wide linearity (0.25–300 µ g·L−1), low detection limits (0.03–0.05 µ g·L−1) and high enrichment factors (767–1411) for the detection of PAHs is explored, coupling BTCH-PTA-COF based SPME with gas chromatography with hydrogen flame detector (GC-FID). The relative standard deviations (RSDs) for inter-day and intra-day extractions of PAHs are ranging from 4.1 % to 9.6 % and 2.9 % to 6.4 %, respectively. The method successfully detected and quantified trace PAHs in tea beverages and river water samples with recoveries from 88.5 % to 104.8 %. The BTCH-PTA-COF coated fiber is ultra-stable in recycled extraction and reused at least 120 times, which could surpass published and commercial SPME fiber. [ABSTRACT FROM AUTHOR]

• An innovative MOFs@COFs-based molecular trap materials were successfully prepared. • The hierarchical core–shell composite was used as solid-phase microextraction (SPME) fiber coating. • The possible adsorption mechanism was systematically verified and explained. • The proposed method provided a new, effective and low-cost method for rapid and superior capture PAHs. In view of the serious carcinogenic, teratogenic and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs), which cause significant harm to human beings and the environment. Therefore, developing rapid adsorption and efficient analytical methods are research topic with practical significance. Herein, an innovative MOFs@COFs-based molecular trap materials were prepared with hierarchical porous core–shell structure and used as solid-phase microextraction (SPME) fiber coating, which combined with high performance liquid chromatography (HPLC) to achieve the efficient separation, capture, and detection for 7 PAHs in real samples. The possible adsorption mechanism was systematically verified and explained. Under the optimized conditions, the method developed in this experiment had a wide linear range (0.005–400 µg·L−1) with a good linear correlation coefficient (R2 > 0.9984), low detection limits (0.002–0.405 µg·L−1, S/N = 3) and low quantification limits (0.005–1.351 µg·L−1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.26–3.64% and 0.40–5.91%, respectively. Besides, the fiber showed higher enrichment capacity and extraction efficiency for PAHs compared to commercial SPME fibers and other material fibers, and exhibited excellent acid-base stability and reproducibility. This work provided a favorable synthetic pathway for the preparation of MOFs@COFs composites by layer-modified assembly synthesis strategy, showed excellent practical applicability as a SPME fiber coating combined with HPLC, and could be realized to provide technical support for future studies on the separation, adsorption, and analysis of PAHs in the petrochemical industrial zone of the Yellow River Basin. [ABSTRACT FROM AUTHOR]

• A hollow Co-MOF-74 incorporated electrospun nanofiber membranes (H-NFMs) were fabricated. • The H-NFMs were installed in a homemade filter to remove PAHs by the drain-type adsorption. • Hydrophobic H-NFMs have good mechanical, fast mass transfer capability, and favorable regeneration properties. • The method provided a new, effective and low-cost strategy for rapid and superior removal of PAHs. Developing efficient adsorbents for the removal of polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions is an attractive and significative task. Herein, we demonstrate a route to fabricate hollow Co-MOF-74 incorporated electrospun nanofiber membranes and combine it with a homemade filter device for drain-type adsorption to remove PAHs from aqueous solutions. The removal efficiency of the prepared H-NFMs were more than 80% (except B[ghi]p = 75%), and exhibited excellent reusability for multiple regeneration cycles. In addition, the introduced H-Co-MOF-74 material possessed a large surface area (633.6 m2 g−1) and hollow structure, which could supply more exposed adsorption active sites, accelerate mass transfer and shorten the adsorption equilibrium time. By loading H-Co-MOF-74 in nanofiber membranes, H-NFMs have high hydrophobicity, good mechanical and thermal stability, while the filters and membranes can be easily recycled separately after the adsorption is completed. This study not only proposed a simple and rapid adsorption method of an efficient sorbent material but also provided an ingenious separation and removal strategy for other pollutants in aqueous solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-67 derived hollow double-shelled Co 3 O 4 /carbon (HoMS-Co 3 O 4) were successfully prepared. • A novel spiral-solid phase microextraction (S-SPME) fiber using HoMS-Co 3 O 4 as coating was designed. • Open a new way for the preparation of hollow multishelled structure using ligand conversion method. • The proposed method provided a new, effective and low-cost method for rapid and superior capture PAHs. Here, a unique spiral-solid phase microextraction (S-SPME) fiber using ZIF-67 derived hollow multishelled structures Co 3 O 4 /carbon nanomaterials (HoMS-Co 3 O 4 /C) as the coating was designed for superior capture of trace polycyclic aromatic hydrocarbons (PAHs). The ligand 2-methylimidazole of ZIF-67 was replaced twice with 2,5-dihydroxyterephthalic acid and followed by pyrolysis to obtain the material with an unique hollow double-shelled structure. The formation of the hollow structure can be explained by the Ostwald ripening. Fifteen PAHs, four brominated flame retardants (BFRs), and seven endocrine chemicals (EDCs) were used to investigate the extraction performance of HoMS-Co 3 O 4 /C coated S-SPME fiber. The spiral fiber displayed higher selectivity for PAHs compared with BFRs and EDCs. The methods had low detection limits (0.002–2.680 μg L−1), wide linear ranges (0.005–1000 μg L−1), and good reproducibility (0.7–10.7%, fiber to fiber). In addition, the S-SPME fiber demonstrated excellent enrichment ability and extraction efficiency for PAHs compared with commercial SPME fibers, it might since there were strong π-π stacking force, hydrophobic interaction between analytes and HoMS-Co 3 O 4 /C coating, also the HoMS coating and the spiral fiber could greatly increase the contact area between adsorbent and target compounds. Finally, the HoMS-Co 3 O 4 /C coated S-SPME fiber had been further adopted to detect fifteen PAHs in environmental water samples successfully. [ABSTRACT FROM AUTHOR]