Fabrication of amino- and hydroxyl dual-functionalized magnetic microporous organic network for extraction of zearalenone from traditional Chinese medicine prior to the HPLC determination.

Efficient enrichment of trace zearalenone (ZEN) from the complex traditional Chinese medicine (TCM) samples is quite difficult, but of great significance for TCM quality control. Herein, we reported a novel magnetic solid phase extraction (MSPE) strategy for ZEN enrichment using the amino- and hydroxyl dual-functionalized magnetic microporous organic network (Fe3O4@MON-NH2-OH) as an advanced adsorbent combined with the high-performance liquid chromatography (HPLC) determination. Efficient extraction of ZEN was achieved via the possible hydrogen bonding, hydrophobic, and π-π interactions between Fe3O4@MON-NH2-OH and ZEN. The adsorption capacity of Fe3O4@MON-NH2-OH for ZEN was 215.0 mg g-1 at the room temperature, which was much higher than most of the reported adsorbents. Under the optimal condition, the developed Fe3O4@MON-NH2-OH-MSPE-HPLC method exhibited wide linear range (5-2500 µg L-1), low limits of detection (1.4-35 µg L-1), less adsorbent consumption (5 mg), and large enhancement factor (95) for ZEN. The proposed method was successfully applied to detect trace ZEN from 10 kinds of real TCM samples. Conclusively, this work demonstrates the Fe3O4@MON-NH2-OH can effectively extract trace ZEN from the complex TCM matrices, which may open up a new way for the application of MONs in the enrichment and extraction of trace contaminants or active constituents from the complex TCM samples.

Sacrificial template synthesis of hollow sulfonate group functionalized microporous organic network for efficient solid phase extraction of sulfonamide antibiotics from milk and honey samples.

The highly conjugated and hydrophobic characteristics of microporous organic networks (MONs) have largely impeded their broad applications in sample pretreatment especially for the polar or ionic analytes. In this work, a novel uniform hollow shaped sulfonate group functionalized MON (H-MON-SO3H-2) was synthesized via the sacrificial template method for the efficient solid phase extraction (SPE) of sulfonamides (SAs) from environmental water, milk, and honey samples prior to HPLC analysis. H-MON-SO3H-2 exhibited large specific surface area, penetrable space, good stability, and numerous hydrogen bonding, electrostatic, hydrophobic and π-π interaction sites, allowing sensitive SPE of SAs with wide linear range (0.150-1000 µg L-1), low limit of detection (0.045-0.188 µg L-1), good precisions (intra-day and inter-day RSD < 7.3%, n = 5), large enrichment factors (95.7-98.5), high adsorption capacities (250.4-545.0 mg g-1), and satisfactory reusability (more than 80 times). Moreover, the established method was successfully applied to extract SAs from spiked samples with the recoveries of 86.1-104.3%. This work demonstrated the great potential of H-MON-SO3H-2 in the efficient SPE of trace SAs in complex environmental water and food samples and revealed the prospect of hollow MONs in sample pretreatment.

Amide and carboxyl dual-functionalized magnetic microporous organic networks for efficient extraction of cephalosporins.

Cephalosporins (CEFs) are a class of widely used toxic antibiotics. Development of a rapid and sensitive method for detecting trace CEF residues in food samples is still challenging. Herein, we report preparation of an amide and carboxyl groups dual-functionalized core-shelled magnetic microporous organic network MMON-COOH-2CONH for efficient magnetic solid-phase extraction (MSPE) of CEFs from milk powder samples. Under optimal conditions, the established MMON-COOH-2CONH-MSPE-HPLC-UV method owns wide linear range (3-10000 µg kg-1), low limits of detection (1-3 µg kg-1), large enrichment factors (93.9-99.4), low adsorbent consumption (3 mg), and short extraction time (6 min). Synergistic extraction mechanisms of ionic bonding, hydrogen bonding, π-π, and hydrophobic interactions were elucidated by both theoretical density functional theory calculations and experimental data. This study confirms that preparation of dual-functionalized MMONs and introduction of ionic groups are feasible to promote MMONs application in sample pretreatment.

Fabrication of magnetic Fe3O4 doped ß-cyclodextrin microporous organic network for the efficient extraction of endocrine disrupting chemicals from food takeaway boxes.

Endocrine disrupting chemicals (EDCs) are a typical class of natural or man-made endogenous hormone agonists or antagonists that can directly or potentially interfere with human endocrine system. However, it is still difficult to analyze trace EDCs directly from complex environment and food matrices. Therefore, the proper sample pretreatment is highly desired and the preparation of efficient adsorbents is of great challenge and importance. Herein, we report the facile one-pot solvothermal synthesis of Fe3O4 nanoparticle doped magnetic ß-cyclodextrin microporous organic network composites (MCD-MONs) for the magnetic solid phase extraction (MSPE) of four phenolic EDCs in water and food takeaway boxes prior to the high-performance liquid chromatography analysis. The sheet-like Fe3O4 doped MCD-MONs offered good magnetic property (16.5 emu g-1) and stability, and provided numerous hydrogen bonding, hydrophobic, π-π, and host-guest interaction sites for EDCs. Under the optimal experimental conditions, the established method was successfully verified with wide linear range (2.0-1000 µg L-1), low limits of detection (0.6-1.0 µg L-1), good precisions (intra-day and inter-day RSDs < 5.2 %, n = 3), large enrichment factors (88-98) and adsorption capacity (90.3-255.8 mg g-1), short extraction time (6 min), less adsorbent consumption (3 mg), and good reusability (at least 8 times) for EDCs. The proposed method was successfully applied to detect the trace EDCs in real samples with the recovery of 84.0-99.7 %. This work demonstrated the great potential of MCD-MONs for the efficient MSPE of trace EDCs from complex food takeaway boxes and water samples and uncovered the prospect of CD-based MONs in sample pretreatment.

Fabrication of zwitterionic magnetic microporous organic network for efficient extraction of fluoroquinolone antibiotics from meat samples.

A zwitterionic magnetic microporous organic network (MMON-SO3H-NH2) with numerous amino and sulfonic acid ion-pare binding sites was designed and synthesized for efficient magnetic solid-phase extraction (MSPE) of fluoroquinolones (FQs) from meat samples. The core-shell MMON-SO3H-NH2 offered large specific surface area, rapid magnetic responsiveness, good stability, and multiple binding sites for FQs. The density functional theory and independent gradient model evaluations confirmed hydrogen bonding, π-π and ion-pair interactions between MMON-SO3H-NH2 and FQs. Under the optimal conditions, the established MMON-SO3H-NH2-MSPE-HPLC-UV method gave wide linear range (0.15-1000 µg L-1), low limits of detection (0.05-4.5 µg L-1) and limits of quantitation (0.15-13 µg L-1), and high enrichment factors (82.1-99.6) using 3 mg of adsorbent. This work demonstrates that the preparation of zwitterionic MONs is an efficient way to promote the extraction performance of MONs for zwitterionic targets and provides an effective sample pretreatment method for enriching and monitoring FQs in complex food matrices.

Microporous Organic Network: Superhydrophobic Coating to Protect Metal-Organic Frameworks from Hydrolytic Degradation.

Despite the rapid development of versatile metal-organic frameworks (MOFs), the synthesis of water-stable MOFs remains challenging, which significantly limits their practical applications. Herein, a novel engineering strategy was developed to prepare superhydrophobic MOFs by an in situ fluorinated microporous organic network (FMON) coating. Through controllable modification, the resulting MOF@FMON retained the porosity and crystallinity of the pristine MOFs. Owing to the superhydrophobicity of the FMON and the feasibility of MOF synthesis, the FMON coating could be in situ integrated with various water-sensitive MOFs to provide superhydrophobicity. The coating thickness and hydrophobicity of the MOF@FMON composites were easily regulated by changing the FMON monomer concentration. The MOF@FMON composites exhibited excellent oil/water separation and catalytic activities and enhanced durability in aqueous solutions. This study provides a general approach for the synthesis of superhydrophobic MOFs, expanding the application scope of MOFs.

Shiwei Qingwen decoction regulates TLR4/NF-κB signaling pathway and NLRP3 inflammasome to reduce inflammatory response in lipopolysaccharide-induced acute lung injury.

ETHNOPHARMACOLOGICAL RELEVANCE: Shiwei Qingwen decoction (SWQ), a Chinese herbal formula based on the classic traditional Chinese medicine prescription Yu Ping Feng San, has shown efficacy in preventing and treating early pneumonia with good clinical outcomes. However, its underlying mechanism is yet unclear. AIM OF THE STUDY: To clarify the preventive and therapeutic effects of SWQ on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and explore the underlying mechanism by which SWQ influences pneumonia. MATERIALS AND METHODS: First, the chemical composition of SWQ was preliminarily determined by high performance liquid chromatography (HPLC), and the impact of SWQ (3.27, 6.55, and 13.1 g/kg) was assessed in the LPS-induced ALI rat model. Next, its inflammatory pathway was determined via network pharmacology. Finally, the molecular mechanism of SWQ was validated using a rat ALI model and a THP-1 cell inflammation model. RESULTS: HPLC identified chlorogenic acid, prime-O-glucosylcimifugin, calycosin, and 5-O-methylaminoside in the chemical profile of SWQ. In the ALI model, SWQ alleviated ALI by reducing lung wet/dry weight ratio (W/D) and preventing histopathological damage to the lungs. At the same time, SWQ decreased penetration of inflammatory mediators by upregulating AQP1 and AQP5 and endothelial nitric oxide synthase (eNOS). Pretreatment with SWQ downregulated white blood cells and neutrophils count in BALF and suppressed LPS-induced expression levels of MPO, NE, and pro-inflammatory factors (TNF-α, IL-1ß, IL-6, and iNOS). Network pharmacology showed that SWQ was associated with TLR4/NF-κB inflammation pathway. Moreover, pretreatment with SWQ reduced the expression level of TLR4/NF-κB signaling pathway-associated proteins (TLR4, Myd88, p-IκB, and p-p65) and NLRP3 inflammasome (NLRP3, ASC, caspase-1, and cleaved-IL-1ß) in vivo and vitro. CONCLUSIONS: The present study demonstrates that SWQ can reduce inflammation in ALI by inhibiting TLR4/NF-κB and NLRP3 inflammasome activation.

Click postsynthesis of microporous organic network@silica composites for reversed-phase/hydrophilic interaction mixed-mode chromatography.

Recently, the good physical and chemical properties, well-defined pore architectures, and designable topologies have made microporous organic networks (MONs) excellent potential candidates in high-performance liquid chromatography (HPLC). However, their superior hydrophobic structures restrict their application in the reversed-phase mode. To solve this obstacle and to expand the application of MONs in HPLC, we realized the thiol-yne "click" postsynthesis of a novel hydrophilic MON-2COOH@SiO2-MER (MER denotes mercaptosuccinic acid) microsphere for reversed-phase/hydrophilic interaction mixed-mode chromatography. SiO2 was initially decorated with MON-2COOH using 2,5-dibromoterephthalic acid and tetrakis(4-ethynylphenyl)methane as monomers, and MER was then grafted via thiol-yne click reaction to yield MON-2COOH@SiO2-MER microspheres (5 µm) with a pore size of ~1.3 nm. The -COOH groups in 2,5-dibromoterephthalic acid and the post-modified MER molecules considerably improved the hydrophilicity of pristine MON and enhanced the hydrophilic interactions between the stationary phase and analytes. The retention mechanisms of the MON-2COOH@SiO2-MER packed column were fully discussed with diverse hydrophobic and hydrophilic probes. Benefiting from the numerous -COOH recognition sites and benzene rings within MON-2COOH@SiO2-MER, the packed column exhibited good resolution for the separation of sulfonamides, deoxynucleosides, alkaloids, and endocrine-disrupting chemicals. A column efficiency of 27,556 plates per meter was obtained for the separation of gastrodin. The separation performance of the MON-2COOH@SiO2-MER packed column was also demonstrated by comparing with those of MON-2COOH@SiO2, commercial C18, ZIC-HILIC, and bare SiO2 columns. This work highlights the good potential of the thiol-yne click postsynthesis strategy to construct MON-based stationary phases for mixed-mode chromatography.

Room-temperature synthesis of dual-functionalized magnetic microporous organic network for efficient extraction of vanillins in food.

Microporous organic networks (MONs) are promising materials for the magnetic solid-phase extraction (MSPE) of trace targets from diverse complex samples. However, all the reported magnetic MONs (MMONs) are mono-functionalized and synthesized by refluxing at high temperatures, which is not an energy-efficient and environmentally friendly method. Here, for the first time, we report the room-temperature fabrication of a novel dual-functionalized MMON (MMON-B) for the efficient MSPE of typical vanillin additives from food samples prior to high-performance liquid chromatography (HPLC). The conjugated MMON-B with numerous -OH and -NH2 groups afforded good extraction for vanillins via π-π, hydrophobic, and hydrogen-bonding interactions. The factors affecting the extraction were studied in detail. Under the optimal conditions, the developed MMON-B-MSPE-HPLC-UV method exhibited wide linear range (0.50-1200 µg L-1), low limits of detection (0.10-0.15 µg L-1), and good reusability and stability. Therefore, MMON-B was successfully used to enrich vanillins in complex food samples. The morphology and extraction efficiency of the room-temperature synthesized MMON-B were comparable with those of the MMON-B synthesized via the conventional reflux method, indicating that the room-temperature fabrication method is a good alternative to the reflux method. This study presents the feasibility of using a room-temperature method for synthesizing dual-functionalized MONs, and the findings may significantly promote the application of MONs in the MSPE of trace targets from complex matrices.

Synthesis of crown ether-based microporous organic networks: A new type of efficient adsorbents for chlorophenols.

Microporous organic networks (MONs) are a booming class of functional materials in elimination of environmental pollutants. However, the limit varieties of MONs still restrict their broad applications. Here we report the synthesis of a novel type of crown ether (CE)-based MONs via the coupling between brominated 18-crown-6 ether and different aromatic alkynyls. The constructed CE-based MONs integrates the good conjugation property of MONs and the inherent host-guest binding sites of CE, allowing the ultrafast and efficient adsorption and removal of a typical environmental priority pollutant 2,4,6-trichlorophenol (2,4,6-TCP). The hydrophobic CE-based MONs can also address the recovery challenge of unstable discrete CE in most organic and inorganic solvents. All CE-based MONs displayed fast adsorption kinetics (< 3 min) and large adsorption capacities (229.1-341.7 mg g-1) for 2,4,6-TCP. The CE-based MONs also gave stable adsorption capacities for 2,4,6-TCP in pH range of 4.0-6.0, NaCl concentration of 0-40 mg L-1, HA concentration of 0-30 mg L-1, or H2O2 ratio of < 5 %. Density functional theory calculation, Fourier transform infrared and X-ray photoelectron spectra evaluation revealed adsorption process involved hydrophobic, π-π and hydrogen bonding interactions. The CE-based MONs also showed favorable reusability and good adsorption for other toxic chlorophenols. This work highlights the potential of CE-based MONs in contaminants elimination.

Monomer-mediated fabrication of microporous organic network@silica microsphere for reversed-phase/hydrophilic interaction mixed-mode chromatography.

Microporous organic networks (MONs) are promising in high performance liquid chromatography (HPLC) with large specific surface area, good hydrophobicity and stability. However, their superhydrophobic structures restrict MONs-based HPLC only in reversed-phase mode. To decrease the hydrophobicity of pristine MONs and to expand their broad application in HPLC, here we described the monomer-mediated fabrication of core-shell MON-2COOH@SiO2 microspheres for reversed-phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode chromatography for the first time. The -COOH groups were introduced into MONs' skeleton to improve their hydrophilicity and to provide hydrophilic interaction sites. The MON-2COOH was grafted onto silica via a monomer mediated method to produce monodispersed core-shell microspheres. By adjusting the concentration of reactants, the thickness of MON-2COOH shell was easily manipulated. The packed MON-2COOH@SiO2 column showed high resolution and selectivity for separating both hydrophobic (alkylbenzenes, polycyclic aromatic hydrocarbons, anilines and phenols) and hydrophilic (nucleoside and nucleic bases) probes, highlighting the promise of MONs in mixed-mode HPLC. The MON-2COOH@SiO2 column also achieved good separation to sulfonamides, nonsteroidal anti-inflammatory drugs, flavonoids and phenylurea herbicides, and offered better resolution than commercial C18 and pristine SiO2 column. Multiple retention mechanisms were also found on MON-2COOH@SiO2 packed column, underlining the great potential of MONs in mixed-mode HPLC.

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.

Synthesis of reusable and renewable microporous organic networks for the removal of halogenated contaminants.

Microporous organic networks (MONs) have shown great potential in the removal of environmental contaminants. However, all studies have focused on the design and construction of novel and efficient adsorbents, and the recycling and reuse of adsorbates were disregarded. In this study, we report a feasible approach to synthesize renewable and reusable MONs by using target halogenated contaminants such as tetrabromobisphenol A (TBBPA), 2,3-dichlorophenol (2,3-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) as starting monomers. TBBPA, 2,3-DCP, and 2,4,6-TCP acted as hazardous contaminants and starting monomers for MONs, leading to the recycling of both adsorbents and adsorbates. The obtained TBBPA-MON, 2,3-DCP-MON, and 2,4,6-TCP-MON not only offered good reusability and large adsorption capacity for their elimination but also provided good adsorption for other phenolic contaminants relying on multiple interactions. Density functional theory calculation indicated the dominant role of π-π and hydrophobic interactions and the secondary role of hydrogen bonding interactions during the adsorption process. The used TBBPA-MON could be reused and the eluted TBBPA could be recycled and renewed for the construction of fresh MONs. This study provided a feasible approach to design and synthesize renewable MONs for environmental contaminants.

Tailored amino/hydroxyl bifunctional microporous organic network for efficient stir bar sorptive extraction of parabens and flavors from cosmetic and food samples.

As an effective sample pretreatment approach, stir bar sorptive extraction (SBSE) has shown great prospects in static microextraction and selective enrichment. In this work, bifunctional microporous organic network (B-MON) with the coexistence of amino and hydroxyl groups was firstly designed and synthesized as a novel coating for efficient SBSE of parabens and flavors in combination with high-performance liquid chromatography coupled with photodiode array detection (HPLC-PDA). Linked by covalent bonds to form an extension of the aromatic ring skeleton, B-MON was a tailored adsorbent featured by porous structure and abundant hydrogen bonding sites for analytes with benzene/naphthalene rings and OH/COOH groups. The extraction and desorption parameters were evaluated in detail. Under the optimized conditions, the proposed B-MON-SBSE-HPLC-PDA method offered good linearity (0.10-100 µg L-1) with correlation coefficients R2 ≥ 0.995, low limits of detection (0.010-0.035 µg L-1) and limits of quantification (0.035-0.115 µg L-1), and favorable enrichment factors (40-49). Furthermore, the developed method has been applied to the analysis of parabens and flavors in cosmetic and food samples with recoveries ranging from 80.4 to 109.6%. This method was also feasible to extract the analytes with benzene/naphthalene rings and OH/COOH groups, such as the plant growth regulators and non-steroidal anti-inflammatory drugs. The present study provided a new way to synthesize bifunctional MONs for SBSE of trace analytes in complex samples.

Thiol-Yne Click Postsynthesis of a Sulfonate Group-Enriched Magnetic Microporous Organic Network for Efficient Extraction of Benzimidazole Fungicides.

The lack of functional groups or binding sites largely hindered the broad application of microporous organic networks (MONs). Herein, we report the fabrication of the sulfonate group-enriched magnetic MON composite (MMON-SO3H@SO3Na) via the combination of the sulfonic acid group containing the monomer and thiol-yne click postmodification for efficient magnetic solid-phase extraction (MSPE) of benzimidazole fungicides (BZDs) from complex sample matrices. The well-defined core-shell-structured MMON-SO3H@SO3Na was obtained and served as an advanced adsorbent for MSPE for concentrating and monitoring trace BZDs. The MMON-SO3H@SO3Na with numerous sulfonate groups provides plenty of ion-exchange, hydrogen-bonding, and π-π sites, leading to the favorable affinity to BZDs via multiple interaction mechanisms. The MMON-SO3H@SO3Na-based MSPE-high-performance liquid chromatography method afforded a wide linear range, low limits of detection, large enrichment factors, good precisions, and reusability for BZDs. Trace BZDs in complex vegetables and fruit samples were successfully detected by the established method. The MMON-SO3H@SO3Na also exhibited good selectivity toward multiple types of polar contaminants containing hydrogen-bonding sites and aromatic structures. This work provided a new postsynthesis strategy for constructing novel and multifunctioned magnetic MONs for preconcentration of trace analytes in a complex matrix.

Fabrication of polyethyleneimine modified magnetic microporous organic network nanosphere for efficient enrichment of non-steroidal anti-inflammatory drugs from wastewater samples prior to HPLC-UV analysis.

Development of novel functionalized adsorbents for efficient magnetic solid phase extraction (MSPE) is essential for promoting their versatile applications in sample pretreatment. Herein, we report the fabrication of a new polyethyleneimine-600 decorated magnetic microporous organic network nanosphere (Fe3O4@MON-PEI600) for effective MSPE of trace non-steroidal anti-inflammatory drugs (NSAIDs) from different water samples. The core-shelled Fe3O4@MON-PEI600 integrates the synergistic effects of Fe3O4, MON and PEI600, providing facile and effective extraction to NSAIDs via multiple hydrogen bonding, π-π and hydrophobic interactions. The inner MON shell employs π-π and hydrophobic interaction sites and the outer PEI-600 coat acts as the hydrogen bonding doner/receptor, which affords good extraction performance for NSAIDs. Under optimal conditions, the Fe3O4@MON-PEI600-MSPE-HPLC-UV method gives wide linear range (0.14-400 µg L-1), low limits of detection (0.042-0.149 µg L-1), good precisions (intra-day and inter-day RSDs < 4.5%, n = 6), and large enrichment factors (97.0-98.2). Extraction mechanisms and selectivity of Fe3O4@MON-PEI600 are evaluated in detail. Moreover, Fe3O4@MON-PEI600 is successfully applied to enrich the trace NSAIDs in different water samples with the concentrations of 0.7 and 0.8 µg L-1 for 1-naphthylacetic acid, 0.5 and 0.1 µg L-1 for naproxen as well as 0.7 µg L-1 for ibuprofen, respectively. The developed method not only affords a novel and efficient magnetic adsorbent for NSAIDs in aqueous media at trace level, but also provides a new strategy for the rational design and synthesis of multiple functionalized MON composites in sample pretreatment.

Fabrication of microporous organic network@silica composite for high-performance liquid chromatographic separation of drugs and proteins.

Microporous organic networks (MONs) that exhibit good stability and hydrophobicity are promising candidates for performing HPLC separation of small organic compounds. However, their applications in separating large analytes as well as biomolecules are still limited by the microporous nature of MONs. Herein, we demonstrated the fabrication of a MON-functionalized silica (MON@SiO2 ), exhibiting micro and mesopores for the HPLC separations of small drugs as well as large analytes, such as flavones, nonsteroidal anti-inflammatory drugs (NSAIDs), endocrine disrupting chemicals (EDCs), and proteins. MON was successfully modified on SiO2 microspheres to yield the uniform and mono-dispersed MON@SiO2 . The separation mechanisms and performance of the MON@SiO2 packed column were evaluated for a wide range of analytes, including neutral, acidic, basic compounds, drugs, and proteins. Compared with commercial C18 and SiO2 -NH2 packed columns, the proposed MON@SiO2 column afforded superior performance in the separations of flavones, NSAIDs, EDCs, and proteins. Moreover, the MON@SiO2 column also offered good repeatability with intraday RSDs (n = 7) of <0.1%, <2.0%, <2.3%, and <0.7% for the retention time, peak height, peak area, and half peak width, respectively, for separating EDCs. This work proved the potential of using MONs in the HPLC separations of drugs and proteins.

Fabrication of magnetic polydopamine@naphthyl microporous organic network nanosphere for efficient extraction of hydroxylated polycyclic aromatic hydrocarbons and p-nitrophenol from wastewater samples.

Herein, we report the fabrication of a novel, well-defined core-double-shell-structured magnetic Fe3O4@polydopamine@naphthyl microporous organic network (MON), Fe3O4@PDA@NMON, for the efficient magnetic extraction of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and p-nitrophenol (p-Npn) from wastewater samples. The hierarchical nanospheres were designed and constructed with the Fe3O4 nanoparticle core, the inner shell of a polydopamine (PDA) layer, and the outer shell of a porous naphthyl MON (NMON) coating, allowing efficient and synergistic extraction of OH-PAHs and p-Npn via hydrophobic, hydrogen bonding, and π-π interactions. The Fe3O4@PDA@NMON nanospheres were well characterized and employed as an efficient sorbent for magnetic solid-phase extraction (MSPE) coupled with high performance liquid chromatography (HPLC) for analyzing of OH-PAHs and p-Npn. Under optimal conditions, the Fe3O4@PDA@NMON-based-MSPE-HPLC-UV method afforded wide linear range (0.18-500 µg L-1), low limits of detection (0.070 µg L-1 for p-Npn, 0.090 µg L-1 for 2-OH-Nap, 0.090 µg L-1 for 9-OH-Fluo and 0.055 µg L-1 for 9-OH-Phe, respectively), large enrichment factors (92.6-98.4), good precisions (intra-day and inter-day relative standard deviations (RSDs); <6.4%, n=6) and less consumption of the adsorbent. Furthermore, trace OH-PAHs and p-Npn with concentrations of 0.29-0.80 µg L-1 were successfully detected in various wastewater samples. Fe3O4@PDA@NMON also functioned as a good adsorbent to enrich a wide scope of trace contaminants containing hydrogen bonding sites and aromatic structures, highlighting the potential of functional MONs in sample pretreatment.

Fabrication of carboxyl functionalized microporous organic network coated stir bar for efficient extraction and analysis of phenylurea herbicides in food and water samples.

Fabrication of novel coatings continues to be an area of great interest and significance in the development and application of stir bar sorptive extraction (SBSE). In this work, a carboxyl-enriched microporous organic network (MON-2COOH) coated stir bar was designed and fabricated as a novel adsorbent for efficient extraction of four phenylurea herbicides (PUHs) before their determination by high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA). The MON-2COOH was represented as an effective adsorbent for PUHs due to its large surface area, rigid porous structure, aromatic pore walls and the desired hydrogen bonding sites of introduced carboxyl groups. Variables affecting the SBSE of target analytes were optimized in detail. Under the optimal extraction conditions, favorable correlation coefficients (R2 > 0.996) in the linear range 0.10-250 µg L-1, low limits of detection (LODs, S/N = 3) of 0.025-0.070 µg L-1 and good enrichment factors (46-49) were obtained. Besides, the proposed SBSE-HPLC-PDA method was successfully applied to determine trace PUHs in food and environmental water samples with recoveries in the range of 80.0-104.8% and the precisions (relative standard deviations, RSDs) lower than 9.9% (n = 3). This work revealed the potential of MONs in SBSE of trace contaminants from environmental samples.

Fabrication of spherical silica amino-functionalized microporous organic network composites for high performance liquid chromatography.

Microporous organic networks (MONs) are a potential class of microporous materials in analytical chemistry. As great efforts have been made in sample pretreatment and gas chromatography, the application of MONs in high performance liquid chromatography (HPLC) has largely lagged and has never been investigated. In addition, directly packing of MONs into columns for HPLC is impractical due to the high column pressure and low column efficiency resulted from the sub-micron sized and irregular MONs. To solve these issues and uncover the possibility of MONs in HPLC, here we report the fabrication of spherical silica amino-functionalized MON (SiO2@MON-NH2) composite as a novel stationary phase for HPLC. Neutral, acidic and alkaline probes were evaluated on SiO2@MON-NH2 packed column. A column efficiency of 21,246 plates per meter was obtained for n-propylbenzene. The results revealed the hydrophobic interaction was the main separation mechanism on SiO2@MON-NH2 packed column. Baseline separation of benzenediol, dichlorophenol, chlorophenol and phenylenediamine position isomers, deoxynucleosides and nucleosides was also achieved on SiO2@MON-NH2 packed column. The relative standard deviations of retention time, peak height and peak area for the studied position isomers, deoxynucleosides and nucleosides were 0.2-0.7%, 0.3-3.7% and 1.7-3.5%, respectively. The SiO2@MON-NH2 packed column also offered better resolution for dichlorophenol isomers, deoxynucleosides and nucleosides than SiO2-NH2 and commercial C18 columns. These results revealed the potential of MONs in HPLC and also provided a new way for the use of nano-sized or irregular MONs in HPLC.