Hydroxylated hierarchical flower-like COF for solid-phase extraction of adrenergic receptor agonists in milk.

A new detection platform based on a hydroxylated covalent organic framework (COF) integrated with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was constructed and used for detecting adrenergic receptor agonists (ARAs) residues in milk. The hydroxylated COF was prepared by polymerization of tris(4-aminophenyl)amine and 1,3,5-tris(4-formyl-3-hydroxyphenyl)benzene and applied to solid-phase extraction (SPE) of ARAs. This hydroxylated COF was featured with hierarchical flower-like morphology, easy preparation, and copious active adsorption sites. The adsorption model fittings and molecular simulation were applied to explore the potential adsorption mechanism. This detection platform was suitable for detecting four α2- and five ß2-ARAs residues in milk. The linear ranges of the ARAs were from 0.25 to 50 µg·kg-1; the intra-day and the inter-day repeatability were in the range 2.9-7.9% and 2.0-10.1%, respectively. This work demonstrates this hydroxylated COF has great potential as SPE cartridge packing, and provides a new way to determine ARAs residues in milk.

Nitrogen-rich based conjugated microporous polymers for highly efficient adsorption and removal of COVID-19 antiviral drug chloroquine phosphate from environmental waters.

Chloroquine phosphate (CQP) has been suggested as an important and effective clinical reliever medication for the 2019 coronavirus (COVID-19). Nevertheless, its excessive use will inevitably cause irreparable damage to the entire ecosystem, thereby posing a considerable environmental safety concern. Hence, the development of highly-efficient methods of removing CQP from water pollution sources, e.g., effluents from hospitals and pharmaceutical factories is significant. This study reported the fabrication of novel C-N bond linked conjugated microporous polymers (CMPs) (BPT-DMB-CMP) with multiple nitrogen-rich anchoring sites for the quick and efficient removal of CQP from aqueous solutions. The irreversible covalent C-N bond linked in the internal framework of BPT-DMB-CMP endowed it with good chemical stability and excellent adsorbent regeneration. With its predesigned functional groups (i.e., rich N-H bonds, triazine rings, and benzene rings) and large area surface (1,019.89 m2·g-1), BPT-DMB-CMP demonstrated rapid adsorption kinetics (25 min) and an extraordinary adsorption capacity (334.70 mg·g-1) for CQP, which is relatively higher than that of other adsorbents. The adsorption behavior of CQP on BPT-DMB-CMP corresponded with Liu model and mixed-order model. Based on the density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS), and adsorption comparisons test, the halogen bonding, and hydrogen bonding cooperates with π - π, C - H···π interactions and size-matching effect in the CQP adsorption system on BPT-DMB-CMP. The excellent practicability for the removal of CQP from real wastewater samples verified the prospect of practical application of BPT-DMB-CMP. BPT-DMB-CMP exhibited the application potentials for the adsorption of other antiviral drugs. This work opens up an efficient, simple, and high adsorption capacity way for removal CQP.

Buchwald-Hartwig coupled conjugated microporous polymer for efficient removal COVID-19 antiviral drug famciclovir from waters: Adsorption behavior and mechanism.

The consumption of famciclovir (FCV) has been increased dramatically since the outbreak of coronavirus in 2019, and the pollution and harm of FCV in waters are concerned. Here, by utilizing aryl halides on 2, 4, 6-tris(4-bromophenyl)- 1, 3, 5-triazine (BPT) and primary amine groups on benzidine (BZ), a novel conjugated microporous polymer, namely BPT-BZ-CMP, was synthesized by Buchwald-Hartwig coupling reaction and applied in the removal of FCV from aqueous solution firstly. The synthesized BPT-BZ-CMP were characterized by various methods, including FTIR, SEM, BET, and Zeta-potential. Due to the micropore structure and high specific surface area, it took only 30 min for BPT-BZ-CMP to adsorb FCV to reach an equilibrium, and the maximum adsorption capacity was 347.8 mg·g-1. The Liu and pseudo-second-order kinetic models properly fit the adsorption equilibrium and kinetic data, respectively. The adsorption process was a spontaneous process, and the hydrogen bonding, π-π interaction and C-H···π interaction enhanced the adsorption of FCV on BPT-BZ-CMP. BPT-BZ-CMP maintained a good adsorption capacity after four consecutive adsorption-desorption cycle experiments. This study confirmed the potential of BPT-BZ-CMP as efficient sorbent to remove FCV from aqueous solutions.

Ionic covalent organic frameworks for the magnetic solid-phase extraction of perfluorinated compounds in environmental water samples.

A novel magnetic ionic covalent organic framework (Fe3O4@EB-iCOFs) was designed and synthesized. It was then characterized by X-ray diffraction, N2 adsorption-desorption analysis, and magnetic measurements, among others. The material shows the advantages of ionic property, large surface area, and magnetic responsiveness. It has potential of magnetic solid-phase extraction (MSPE) of perfluorinated compounds (PFCs). A method for the determination of PFCs based on MSPE-HPLC-MS/MS was established. The method has excellent linearity (r ≥ 0.995) in the working range 1-1000 ng L-1 , good repeatability (1.4-5.8%, n = 6), low limits of detection in the range 0.1-0.8 ng L-1 and satisfactory recoveries (between 73.9 and 108.3%).

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 (0.08-0.21 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 (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.

Magnetic covalent triazine-based frameworks as magnetic solid-phase extraction adsorbents for sensitive determination of perfluorinated compounds in environmental water samples.

Covalent organic frameworks (COFs), which are a new type of carbonaceous polymeric material, have attracted great interest because of their large surface area and high chemical and thermal stability. However, to the best of our knowledge, no work has reported the use of magnetic COFs as adsorbents for magnetic solid-phase extraction (MSPE) to enrich and determine environmental pollutants. This work aims to investigate the feasibility of using covalent triazine-based framework (CTF)/Fe2O3 composites as MSPE adsorbents to enrich and analyze perfluorinated compounds (PFCs) at trace levels in water samples. Under the optimal conditions, the method developed exhibited low limits of detection (0.62-1.39 ng·L-1), a wide linear range (5-4000 ng L-1), good repeatability (1.12-9.71%), and good reproducibility (2.45-7.74%). The new method was successfully used to determine PFCs in actual environmental water samples. MSPE based on CTF/Fe2O3 composites exhibits potential for analysis of PFCs at trace levels in environmental water samples. Graphical abstract Magnetic covalent triazine-based frameworks (CTFs) were used as magnetic solid-phase extraction adsorbents for the sensitive determination of perfluorinated compounds in environmental water samples. PFBA perfluorobutyric acid, PFBS perfluorobutane sulfonate, PFDA perfluorodecanoic acid, PFDoA perfluorododecanoic acid, PFHpA perfluoroheptanoic acid, PFHxA perfluorohexanoic acid, PFHxS perfluorohexane sulfonate, PFNA perfluorononanoic acid, PFOA perfluorooctanoic acid, PFPeA perfluoropentanoic acid, PFUdA Perfluoroundecanoic acid.

Covalent triazine-based frameworks/iron oxide for highly sensitive magnetic solid-phase extraction of phenolic pollutants in water samples.

This study demonstrates for the first time the enrichment potential of covalent triazine-based frameworks/iron oxide for the magnetic solid-phase extraction of seven typical polar phenolic pollutants. Important parameters, such as the eluant and its volume, adsorbent amounts, sample pH, extraction time, and ionic strength, were optimized in detail. Under the optimal conditions, low limits of detection (0.09-0.53 ng/mL), wide linear range (25-2000 ng/mL), good repeatability (1.2-8.3%) and reproducibility (1.5-9.9%) were achieved. The developed method was successfully applied to analyze the target phenols at trace levels in environmental water samples.

A hollow microporous organic network as a fiber coating for solid-phase microextraction of short-chain chlorinated hydrocarbons.

A solid-phase microextraction (SPME) fiber coated with a hollow microporous organic network (H-MON) was fabricated for the analysis of short-chain chlorinated paraffins (SCCPs). The sorbent was prepared by reacting tetra(4-ethynylphenyl)methane and 1,4-diiodobenzene using bis-(triphenylphosphine) palladium(II) as the catalyst in the presence of silica sphere templates, which then were removed by hydrofluoric acid. The SCCPs were quantified by GC-MS working in the negative chemical ionization mode. The H-MON has a high specific surface (701 m2·g-1) and microporosity (pore size <2 nm). Extraction temperature, extraction time, and ionic strength of the sample solutions were optimized by using the Box-Behnken design. The head-space SPME exhibits better extraction performance than the direct immersion mode. Under optimal working conditions, the detection limit (3 times of the standard deviation) is 0.03 ng·mL-1 in the water samples. Response is linear in the 0.05-10 ng·mL-1 concentration range. Repeatability and reproducibility, expressed as the relative standard deviations, ranged from 4.6 to 11.0%. The method was successfully applied in the analysis of SCCPs in water, sediments, organisms, and atmospheric particulate matter samples. Graphical abstract Schematic of the fabrication of a hollow microporous organic network (H-MON) on stainless steel fibers for use in SPME. The method was applied to the determination of short-chain chlorinated paraffins in biological, environmental water and atmospheric particulate matter (PM2.5) samples.

A Zr(IV)-based porphyrinic metal-organic framework as a solid-phase sorbent for extraction of sulfonamides prior to their quantitation by LC-MS.

A porphyrinic metal-organic framework (PCN-224) was fabricated and used as an adsorbent for solid-phase extraction of ultratrace levels of polar sulfonamide antibiotics from food and drinking waters. The PCN-224 was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and powder X-ray diffraction analyses. Parameters affecting the extraction efficiency were optimized. The sulfonamides were quantified by liquid chromatography-tandem mass spectrometry. Figures of merit include (a) low limits of detection (0.07-0.47 ng·L-1), (b) wide linear ranges (0.5-2000 ng·L-1), and (c) good repeatabilities (2.8%-6.7%) and reproducibilities (1.7%-5.1%). The method was successfully applied to the determination of sulfonamides in food and drinking water samples. Graphical abstract A Zr(IV)-based porphyrinic metal-organic framework (PCN-224) was synthesized from a Zr6 cluster and the H2TCPP ligand. It was used for solid-phase extraction of sulfonamides from food and drinking water samples coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination.

Porous covalent organonitridic frameworks for solid-phase extraction of sulfonamide antibiotics.

Porous covalent organonitridic frameworks (PCONFs) were applied as a packing in a solid-phase extraction cartridge for rapid extraction of eight sulfonamide antibiotics from complex samples. The detection was performed by liquid chromatography-tandem mass spectrometry under the multiple reaction monitoring mode. This enabled ultrasensitive, dependable and cost-effective simultaneous analysis of sulfacetamide, sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethoxazole and sulfisoxazole. Main parameters affecting the performance of the PCONF-packed cartridge were investigated. Under optimized conditions, this method has attractive features such as wide linear ranges (2.5-1000 ng·L-1), low limits of detection (0.14-2.0 ng·L-1), and good repeatability (intra-day assay: 2.1%-5.6%; inter-day assay: 2.3%-12.9%). It was successfully applied in the analysis of sulfonamide residues in water, milk and chicken meat samples. Graphical abstract The use of a porous covalent organonitridic framework (PCONFs) as solid-phase extraction (SPE) material is described here for the first time. An ultrasensitive, dependable and cost-effective method was developed for simultaneous analysis of eight sulfonamide residues in water, milk and chicken meat samples by coupling PCONF-based SPE with liquid chromatography-tandem mass spectrometry.

Highly Stable Zr(IV)-Based Porphyrinic Metal-Organic Frameworks as an Adsorbent for the Effective Removal of Gatifloxacin from Aqueous Solution.

Water stable Zr-metal−organic framework nanoparticles (PCN-224 NPs, PCN refers to porous coordination network) have been solvothermally synthesized. PCN-224 NPs show spherical shape with smooth surface and particle size of approximately 200 nm. PCN-224 NPs can be stable in acid and aqueous solutions, as confirmed by powder X-ray diffraction. Gatifloxacin (GTF) adsorption measurements showed that PCN-224 NPs exhibit a high adsorption capacity of 876 mg·g−1. Meanwhile, the adsorption factors, adsorption characteristics, and mechanisms of GTF were investigated in batch adsorption experiments.

Preconcentration and Determination of Perfluoroalkyl Substances (PFASs) in Water Samples by Bamboo Charcoal-Based Solid-Phase Extraction Prior to Liquid Chromatography-Tandem Mass Spectrometry.

In this work, bamboo charcoal was used as solid-phase extraction adsorbent for the enrichment of six perfluoroalkyl acids (PFAAs) in environmental water samples before liquid chromatography-tandem mass spectrometry analysis. The specific porous structure, high specific surface area, high porosity, and stability of bamboo charcoal were characterized. Several experimental parameters which considerably affect extraction efficiency were investigated and optimized in detail. The experimental data exhibited low limits of detection (LODs) (0.01-1.15 ng/L), wide linear range (2-3 orders of magnitude and R ≥ 0.993) within the concentration range of 0.1-1000 ng/L, and good repeatability (2.7-5.0%, n = 5 intraday and 4.8-8.3%, n = 5 interday) and reproducibility (5.3-8.0%, n = 3). Bamboo charcoal was successfully used for the enrichment and determination of PFAAs in real environmental water samples. The bamboo charcoal-based solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry analysis possessed great potential in the determination of trace PFAA levels in environmental water samples.

Aminosilanized magnetic carbon microspheres for the magnetic solid-phase extraction of bisphenol A, bisphenol AF, and tetrabromobisphenol A from environmental water samples.

Aminosilanized magnetic carbon microspheres as a novel adsorbent were designed and fabricated. The adsorbent was used for the magnetic solid-phase extraction of bisphenols at trace levels from environmental water samples before liquid chromatography with tandem mass spectrometry analysis. The structure, surface, and magnetic behavior of the as-prepared aminosilanized magnetic carbon microspheres were characterized by elemental analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, and vibrating sample magnetometry. The effects of the experimental parameters were investigated by the Plackett-Burman design, and then the parameters that were significant to the extraction efficiencies were optimized through a response surface methodology. The aminosilanized magnetic carbon microspheres exhibited high adsorption efficiency and selectivity for bisphenols. Under optimal conditions, low limits of detection (0.011-2.22 ng/L), and a wide linear range (2-3 orders of magnitude), good repeatability (4.7-7.8%, n = 5), and reproducibility (6.0-8.3%, n = 3) were achieved. The results demonstrate that the novel adsorbent possesses great potentials in the determination of trace levels of bisphenols in environmental water samples.

Simultaneous determination of copper, cobalt, and mercury ions in water samples by solid-phase extraction using carbon nanotube sponges as adsorbent after chelating with sodium diethyldithiocarbamate prior to high performance liquid chromatography.

Recently, a sponge-like material called carbon nanotube sponges (CNT sponges) has drawn considerable attention because it can remove large-area oil, nanoparticles, and organic dyes from water. In this paper, the feasibility of CNT sponges as a novel solid-phase extraction (SPE) adsorbent for the enrichment and determination of heavy metal ions (Co(2+), Cu(2+), and Hg(2+)) was investigated for the first time. Sodium diethyldithiocarbamate (DDTC) was used as the chelating agent and high performance liquid chromatography (HPLC) for the final analysis. Important factors which may influence extraction efficiency of SPE were optimized, such as the kind and volume of eluent, volume of DDTC, sample pH, flow rate, etc. Under the optimized conditions, wide range of linearity (0.5-400 µg L(-1)), low limits of detection (0.089~0.690 µg L(-1); 0.018~0.138 µg), and good repeatability (1.27~3.60 %, n = 5) were obtained. The developed method was applied for the analysis of the three metal ions in real water samples, and satisfactory results were achieved. All of these findings demonstrated that CNT sponges will be a good choice for the enrichment and determination of target ions at trace levels in the future.

Cadmium(II)-based metal-organic nanotubes as solid-phase microextraction coating for ultratrace-level analysis of polychlorinated biphenyls in seawater samples.

In this study, stable cadmium(II)-based metal-organic nanotubes (Cd-MONTs) were prepared and used as a coating material for solid-phase microextraction (SPME) of polychlorinated biphenyls (PCBs) from environmental water samples. The as-prepared Cd-MONT SPME coating material was characterized by thermal gravimetric analysis, scanning electron microscopy, and X-ray diffraction. The synthesized Cd-MONTs exhibited high thermal stability (385 °C) and excellent extraction performance toward PCBs. The important conditions were optimized systematically by the response surface method. Under the optimal conditions, the new fiber achieved high enrichment factors (938-3417), low limits of detection (1.80-8.73 pg L-1), and wide linearity (10-5000 pg L-1). The method developed was used in ultratrace-level analysis of PCBs in seawater samples, with satisfactory results for each sample.

Enrichment and determination of polybrominated diphenyl ethers in environmental water samples by magnetic solid-phase extraction with core-shell magnetic carbon microspheres before gas chromatography with mass spectrometry.

Core-shell magnetic carbon microspheres were synthesized by a simple hydrothermal method and used as a novel magnetic solid-phase extraction adsorbent for the sensitive determination of polybrominated diphenyl ethers in environmental water samples. Gas chromatography with negative chemical ionization mass spectrometry was adopted for the detection. Box-Behnken design was used to investigate and optimize important magnetic solid-phase extraction parameters through response surface methodology. Under the optimal conditions, low limits of detection (0.07-0.17 ng·L(-1) ), a wide linear range (1-1000 ng·L(-1) ), and good repeatability (0.80-4.58%) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained in the range of 72.8-97.9%. These results indicated that core-shell magnetic carbon microspheres have great potential as an adsorbent for the magnetic solid-phase extraction of polybrominated diphenyl ethers at trace levels from environmental water samples.

Enrichment and determination of octylphenol and nonylphenol in environmental water samples by solid-phase microextraction with carboxylated carbon nano-spheres coating prior to gas chromatography-mass spectrometry.

In this paper, a novel and simple method for the sensitive determination of endocrine disrupter compounds octylphenol (OP) and nonylphenol (NP) in environmental water samples has been developed using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. Carboxylated carbon nano-spheres (CNSs-COOH) are used as a novel SPME coating via physical adhesion. The CNSs-COOH fiber possessed higher adsorption efficiency than 100 µm polydimethysiloxane (PDMS) fiber and was similar to 85 µm polyacrylate (PA) fiber for the two analytes. Important parameters, such as extraction time, pH, agitation speed, ionic strength, and desorption temperature and time, were investigated and optimized in detail. Under the optimal parameters, the developed method achieved low limits of detection of 0.13~0.14 ng·L(-1) and a wide linear range of 1~1000 ng·(-1) for OP and NP. The novel method was validated with several real environmental water samples, and satisfactory results were obtained.

Accelerated solvent extraction combined with dispersive liquid-liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples.

A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9-110%. These findings indicate that accelerated solvent extraction with dispersive liquid-liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.

Feasibility of hydrofluoric acid etched sand particles for enrichment and determination of polychlorinated biphenyls at trace levels in environmental water samples.

This study aims to investigate the feasibility of etched sand particles being used as solid-phase extraction adsorbents to enrich polychlorinated biphenyls (PCBs), which are typical persistent organic pollutants in the environment, at trace levels. Gas chromatography-tandem mass spectrometry was selected to detect the compounds. Etched sand particles exhibited excellent merits on the enrichment of PCBs. Related important factors affecting extraction efficiencies were investigated and optimized in detail. Under optimized conditions, low limits of detection (0.42 to 3.69 ng L(-1)), wide linear range (10 to 1,000 ng L(-1)), and high repeatability (1.9 to 8.2%) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained. All of these findings indicate that etched sand particles would be useful for the enrichment and determination of organic pollutants at trace levels in water samples.

Sensitive determination of polychlorinated biphenyls in environmental water samples by headspace solid-phase microextraction with bamboo charcoal@iron oxide black fibers prior to gas chromatography with tandem mass spectrometry.

We have investigated the feasibility of bamboo charcoal@iron oxide black for the headspace solid-phase microextraction of polychlorinated biphenyls in environmental water samples. Bamboo charcoal@iron oxide black was prepared and used as a solid-phase microextraction coating material, and gas chromatography with tandem mass spectrometry was used for detection. Several important factors affecting the extraction efficiency were systematically investigated and optimized. Under the optimum conditions, the experimental data exhibited wide linear range over the range 0.2-1000 ng/L and low limits of detection in the range of 4.7-22.2 pg/L. The novel coating was successfully used for the enrichment and determination of polychlorinated biphenyls in real environmental water samples. All these results indicated that bamboo charcoal@iron oxide black-based headspace solid-phase microextraction coupled to gas chromatography with tandem mass spectrometry was an excellent alternative for the sensitive analysis of polychlorinated biphenyls at ultratrace levels in the environment.