Recent advances in applications of metal–organic frameworks for sample preparation in pharmaceutical analysis

New Strategies for the Extraction of Antioxidants from Fruits and Their By-Products: A Systematic Review

This review highlights the recent advancements in extraction techniques for bioactive compounds from natural sources, focusing on methodologies that enhance both efficiency and sustainability. Techniques such as pressurized hot water extraction (PHWE), solid-state fermentation (SSF), ionic liquids (ILs), and electrohydrodynamic (EHD) methods have shown significant potential in improving extraction yields while preserving the bioactivity of target compounds. These innovative approaches offer significant advantages over traditional methods, including reduced energy consumption, minimal environmental impact, and the ability to extract thermosensitive compounds. PHWE and EHD are particularly effective for extracting antioxidants and thermosensitive compounds, whereas SSF provides an environmentally friendly alternative by valorizing agro-industrial waste. Ionic liquids, although promising for extracting complex phytochemicals, face challenges related to scalability and economic feasibility. The adoption of these advanced techniques represents a shift toward more sustainable and cost-effective extraction processes, promoting the discovery and utilization of high-value compounds. These methods also contribute to the development of eco-friendly, cost-effective strategies that align with green chemistry principles and regulatory standards. However, further research and technological advancements are required to address existing limitations and ensure the widespread application of these methods in industrial and pharmaceutical sectors.

Recent advances in methods of extraction, pre-concentration, purification, identification, and quantification of kaempferol

As a naturally widely-occurring dietary, cosmetic, and therapeutic flavonoid, kaempferol has gained much consideration for its nutritional and pharmaceutical properties in recent years. Although there have been performed a high number of studies associated with different aspects of kaempferol's analytical investigations, the lack of a comprehensive summary of the various methods and other plant sources that have been reported for this compound is being felt, especially for many biological applications. This study, aimed to provide a detailed compilation consisting of sources (plant species) and analytical information that was precisely related to the natural flavonoid (kaempferol). There is a trend in analytical research that supports the application of modern eco-friendly instruments and methods. In conclusion, ultrasound-assisted extraction (UAE) is the most general advanced method used widely today for the extraction of kaempferol. During recent years, there is an increasing tendency towards the identification of kaempferol by different methods.

Reshaping Capillary Electrophoresis With State-of-the-Art Sample Preparation Materials: Exploring New Horizons

Capillary electrophoresis (CE) is a powerful analysis technique with advantages such as high separation efficiency with resolution factors above 1.5, low sample consumption of less than 10 µL, cost-effectiveness, and eco-friendliness such as reduced solvent use and lower operational costs. However, CE also faces limitations, including limited detection sensitivity for low-concentration samples and interference from complex biological matrices. Prior to performing CE, it is common to utilize sample preparation procedures such as solid-phase microextraction (SPME) and liquid-phase microextraction (LPME) in order to improve the sensitivity and selectivity of the analysis. Recently, there have been advancements in the development of novel materials that have the potential to greatly enhance the performance of SPME and LPME. This review examines various materials and their uses in microextraction when combined with CE. These materials include carbon nanotubes, covalent organic frameworks, metal-organic frameworks, graphene and its derivatives, molecularly imprinted polymers, layered double hydroxides, ionic liquids, and deep eutectic solvents. The utilization of these innovative materials in extraction methods is being examined. Analyte recoveries and detection limits attained for a range of sample matrices are used to assess their effects on extraction selectivity, sensitivity, and efficiency. Exploring new materials for use in sample preparation techniques is important as it enables researchers to address current limitations of CE. The development of novel materials has the potential to greatly enhance extraction selectivity, sensitivity, and efficiency, thereby improving CE performance for complex biological analysis.

Preparation of cylindrical Chitosan/β-Cyclodextrin/MIL-68(Al) foam column for solid-phase extraction of sulfonamides in water, urine, and milk

This study describes the preparation of a cylindrical polymer foam column termed Chitosan/β-Cyclodextrin/MIL-68(Al) (CS/β-CD/MIL-68(Al)). An ice template-freeze drying technique was employed to prepare the CS/β-CD/MIL-68(Al) foam column by embedding MIL-68(Al) in a polymer matrix comprising cross-linked chitosan (CS) and β-cyclodextrin (β-CD). The cylindrical CS/β-CD/MIL-68(Al) foam was subsequently inserted into a syringe to develop a solid phase extraction (SPE) device. Without the requirement for an external force, the sample solution passed easily through the SPE column thanks to the porous structure of the CS/β-CD/MIL-68(Al) foam column. Moreover, the CS/β-CD/MIL-68(Al) foam column was thought to be a superior absorbent for SPE since it included the adsorptive benefits of CS, β-CD, and MIL-68(Al). The SPE was utilized in conjunction with high-performance liquid chromatography to analyze six sulfonamides found in milk, urine, and water. With matrix effects ranging from 80.49 % to 104.9 % with RSD values of 0.4-14.0 %, the method showed high recoveries ranging from 80.6 to 107.4 % for water samples, 93.4-105.2 % for urine, and 87.4-100.9 % for milk. It also demonstrated good linearity in the range of 10-258 ng·mL-1 with the limits of detection ranging from 1.88 to 2.58 ng·mL-1. The cylindrical CS/β-CD/MIL-68(Al) foam column prepared in this work offered several advantages, including its simple fabrication, excellent water stability, absence of pollutants, biodegradability, and reusability. It is particularly well-suited for SPE. Furthermore, the developed SPE method, employing CS/β-CD/MIL-68(Al) foam column, is straightforward and precise, and its benefits, including affordability, ease of preparation, lack of specialized equipment, and solvent economy, underline its broad applicability for the pretreatment of aqueous samples.

Fabrication of a β-CD-functionalized magnetic microporous organic network for effective enrichment and detection of fluoroquinolone antibiotics in water samples

Fluoroquinolone (FQ) antibiotics, one of the leading environmental pollutants, have ecotoxic effects that can accumulate through ecosystems and harm human health. The determination of FQs is still difficult due to the complex matrix, many interfering factors, and low concentration. Hence, a magnetic microporous organic network (MON) composite denoted as Fe3O4@MON-NH2@CM-β-CD with excellent FQ adsorption performance was prepared by β-CD covalent modification of a MON. Based on the existence of π-π packing, hydrophobic interaction, and hydrogen bonding between Fe3O4@MON-NH2@CM-β-CD and FQs, a new magnetic solid phase extraction (MSPE) method for the enrichment of FQs was developed. Under optimized MSPE conditions, five FQs were detected by HPLC-UV with good linearity (R2 ≥ 0.9989) in the range of 0.02-1 μg mL-1, and detection limits (S/N = 3) in the range of 0.0014-0.0023 μg mL-1. The satisfactory recoveries ranged from 93.1 to 116.2% with RSDs lower than 8.39% when applied to actual environmental water samples. These results revealed that Fe3O4@MON-NH2@CM-β-CD as an adsorbent for MSPE had excellent performance for FQ extraction from real samples, and the MON material types were expanded through the functionalization of MONs, which would have great potential for further application in various analytical methods.

Well-defined Fe3O4@MIL-100(Fe) hollow nanoflower heterostructures for selective dection and monitoring of benzoylurea insecticides from food and water

Developing a platform for the selective detection and effective monitor of toxic contaminants is a major challenge to address organic contaminants contamination in environmental science. Here, for the first time, the thickness-controllable Fe3O4@MIL-100(Fe) heterogeneous materials with special hollow nanoflower (HFs) morphology had been synthesized. The morphology and shell thickness of the nano-petal could be tuned by changing the reaction time. The resultant Fe3O4@MIL-100(Fe) HFs exhibited the hollow nanoflower shapes and exposed abundant accessible active sites. The enrichment performance of Fe3O4@MIL-100(Fe) HFs was approximately 1.4-1.7 times that of spherical Fe3O4@MIL-100(Fe) composite for benzoylurea insecticides (BUs). Furthermore, the optimal sample achieved the wide linearity (0.05-500 ng mL-1) and low limits of detection, (0.003-0.01 ng mL-1) for BUs. The research provides a new strategy for highly sensitive detection and monitoring of harmful pollutant levels in the environment.

NiGA MOF-based dispersive micro solid phase extraction coupled to temperature-assisted evaporation using low boiling point solvents for the extraction and preconcentration of butylated hydroxytoluene and some phthalate and adipate esters

The first-ever attempt to apply nickel gallic acid metal-organic framework (NiGA MOF) in analytical method development was done in this research by the extraction of some plasticizers from aqueous media. The greenness of the method is owing to the use of gallic acid and nickel as safe reagents and water as the safest solvent. Low boiling point solvents were applied as desorption solvents that underwent temperature-assisted evaporation in the preconcentration step. Performing the evaporation using a low-temperature water bath for a short period of time streamlines the preconcentration section. Into the solution of interest enriched with sodium sulfate, a mg amount of NiGA MOF was added alongside vortexing to extract the analytes. Following centrifugation and discarding the supernatant, a μL level of diethyl ether was added onto the analyte-loaded NiGA MOF particles and vortexed. The analyte-enriched diethyl ether phase was transferred into a conical bottom glass test tube and located in a water bath set at the temperature of 35 °C under a laboratory hood. After the evaporation, a μL level of 1,2-dibromoethane was added to the test tube and vortexed to dissolve the analytes from the inner perimeter of the tube. One microliter of the organic phase was injected into a gas chromatograph equipped with flame ionization detection. Appreciable extraction recoveries (61-98%), high enrichment factors (305-490), low limits of detection (0.80-1.74 μg L-1) and quantification (2.64-5.74 μg L-1), and wide linear ranges (5.74-1000 μg L-1) were obtained at the optimum conditions.

Advanced porous organic materials for sample preparation in pharmaceutical analysis

The development of novel sample preparation media plays a crucial role in pharmaceutical analysis. To facilitate the extraction and enrichment of pharmaceutical molecules in complex samples, various functionalized materials have been developed and prepared as adsorbents. Recently, some functionalized porous organic materials have become adsorbents for pharmaceutical analysis due to their unique properties of adsorption and recognition. These advanced porous organic materials, combined with consequent analytical techniques, have been successfully used for pharmaceutical analysis in complex samples such as environmental and biological samples. This review encapsulates the progress of advanced porous materials for pharmaceutical analysis including pesticides, antibiotics, chiral drugs, and other compounds in the past decade. In addition, we also address the limitations and future trends of these porous organic materials in pharmaceutical analysis.

Review: Synthesis of metal organic framework-based composites for application as immunosensors in food safety

Ensuring food safety continues to be one of the major global challenges. For effective food safety monitoring, fast, sensitive, portable, and efficient food safety detection strategies must be devised. Metal organic frameworks (MOFs) are porous crystalline materials that have attracted attention for use in high-performance sensors for food safety detection owing to their advantages such as high porosity, large specific surface area, adjustable structure, and easy surface functional modification. Immunoassay strategies based on antigen-antibody specific binding are one of the important means for accurate and rapid detection of trace contaminants in food. Emerging MOFs and their composites with excellent properties are being synthesized, providing new ideas for immunoassays. This article summarizes the synthesis strategies of MOFs and MOF-based composites and their applications in the immunoassays of food contaminants. The challenges and prospects of the preparation and immunoassay applications of MOF-based composites are also presented. The findings of this study will contribute to the development and application of novel MOF-based composites with excellent properties and provide insights into advanced and efficient strategies for developing immunoassays.

Removal of multiple lipids from human plasma using a hydroxyl-functionalized covalent organic framework aerogel as a new sorbent

A hydroxyl-functionalized covalent organic framework aerogel COFTHB-TAPB-aerogel was designed and prepared as an adsorbent for the removal of multiple lipids from human plasma. The applications of 1,3,5-tris(4'-hydroxy-5'-formylphenyl)benzene (THB) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) as monomers, DMSO/mesitylene (v/v, 4/1) as reaction solvent, and n-propylamine as reaction regulator endow COFTHB-TAPB-aerogel with good adsorption performance for multiple lipids. The morphology, phase purity, specific surface area, pore size, surface charge, and stability of COFTHB-TAPB-aerogel were characterized. Adsorption thermodynamics and adsorption kinetics studies showed that COFTHB-TAPB-aerogel had high equilibrium adsorption capacities (> 15913 mg g-1) and fast adsorption equilibrium (≤ 10 s) for the four model lipids tested. COFTHB-TAPB-aerogel had good reusability with the removal of the model lipids being still more than 91% after 10 use cycles. The sample pretreatment conditions and adsorbent amounts used in lipids removal experiments were optimized. Under the optimized conditions, the method of ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) using COFTHB-TAPB-aerogel as solid-phase extraction sorbent was validated with negligible matrix effects (0.4-3.0%) and good accuracy (86.7-110%) and was applied to determine  20 amino acids in human plasma samples from healthy individuals and gastric adenocarcinoma (GA) patients. The established method has been proved to have good application potential for the removal of multiple lipids in human plasma to reduce the matrix effects and improve the accuracy of clinical LC-MS analysis.

Magnetic metal-organic frameworks immobilized enzyme-based nano-biocatalytic systems for sustainable biotechnology

Nanobiocatalysts, in which enzyme molecules are integrated into/onto multifunctional materials, such as metal-organic frameworks (MOFs), have been fascinating and appeared as a new interface of nanobiocatalysis with multi-oriented applications. Among various nano-support matrices, functionalized MOFs with magnetic attributes have gained supreme interest as versatile nano-biocatalytic systems for organic bio-transformations. From the design (fabrication) to deployment (application), magnetic MOFs have manifested notable efficacy in manipulating the enzyme microenvironment for robust biocatalysis and thus assure requisite applications in several areas of enzyme engineering at large and nano-biocatalytic transformations, in particular. Magnetic MOFs-linked enzyme-based nano-biocatalytic systems offer chemo-regio- and stereo-selectivities, specificities, and resistivities under fine-tuned enzyme microenvironments. Considering the current sustainable bioprocesses demands and green chemistry needs, we reviewed synthesis chemistry and application prospects of magnetic MOFs-immobilized enzyme-based nano-biocatalytic systems for exploitability in different industrial and biotechnological sectors. More specifically, following a thorough introductory background, the first half of the review discusses various approaches to effectively developed magnetic MOFs. The second half mainly focuses on MOFs-assisted biocatalytic transformation applications, including biodegradation of phenolic compounds, removal of endocrine disrupting compounds, dye decolorization, green biosynthesis of sweeteners, biodiesel production, detection of herbicides and screening of ligands and inhibitors.

Novel amino-functionalized magnetic metal-organic framework/layered double hydroxide adsorbent for microfluidic solid phase extraction: Application for vitamin D3

Vitamin D deficiency is highly prevalent worldwide, especially with limited sun exposure and sun avoidance. Thus, reliable monitoring of vitamin D levels in food and biological samples is vital for medicinal diagnosis. Herein, a potent method for the extraction and determination of vitamin D₃ is presented using a microchip-based solid-phase extraction (SPE) device followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. A new magnetic adsorbent based on Fe₃O₄ magnetic nanoparticles (MNPs) modified ZnFe layered double hydroxide (LDH)/2-aminoterephthalic acid-Zn²⁺ metal-organic framework (IRMOF-3) composite (IRMOF-3@MLDH) was successfully synthesized and fixed inside a rectangular micro-column (4 × 2 × 12 mm). The porous structure and high surface area of IRMOF-3@MLDH provide abundant adsorbing sites and make it a potent SPE adsorbent, with an exceptional ability to retain vitamin D₃. The adsorption isotherm showed that the composite was highly efficient at extracting vitamin D₃ with an extraction capacity of 126 mg g^-1. The designed extraction microchip simplified the SPE process, paving the way for automated SPE systems. The developed method presented a broad linear range of 5-2000 ng mL^-1, with a detection limit of 1.4 ng mL^-1. In comparison to conventional silica-based adsorbents, a higher sensitivity was obtained in the determination of vitamin D₃ using the IRMOF-3@MLDH adsorbent. The selectivity of the method was also satisfactory, enabling the measurement of vitamin D₃ in food and blood samples with high recovery values in the range from 95.2 to 101%. Thus, the newly developed adsorbent and method offer an efficient alternative to the commonly used C18-based approach.

Extraction and determination of terpenoids from Zexie Decoction based on a porous organic cage-doped monolithic cartridge

A monolithic solid-phase extraction (SPE) cartridge packed with a composite adsorbent was fabricated via polymerization using dodecene as the monomer with the porous organic cage (POC) material doped, combing with an analytical column through a high-performance liquid chromatography (HPLC) instrument, which was used for the online extraction and separation of 23-acetyl alismol C, atractylodes lactone II and atractylodes lactone III from Zexie Decoction. The POC-doped adsorbent shows porous structure with a relatively high specific surface area of 85.50 m²/g, which was obtained from the characterizations of a scanning electron microscope and an automatic surface area and porosity analyser. Efficient extraction and separation of three target terpenoids was achieved by an online SPE-HPLC method based on the POC-doped cartridge, which exhibits strong matrix-removal ability and good terpenoids-retention ability with a high adsorption capacity, due to the interactions of hydrogen bond and hydrophobicity between the terpenoids and the POC-doped adsorbent. Method validation shows good linearity (r ≥ 0.9998) of the regression equation, and high accuracy with the spiked recovery in the range of 99.2 %-100.8 % of the proposed method. Compared to the generally disposable adsorbent, this work fabricated a reusable monolithic cartridge, which can be used for at least 100 times, with the RSD based on the peak area of the three terpenoids less than 6.6 %.

Progress in pre-treatment and extraction of organic and inorganic pollutants by layered double hydroxide for trace-level analysis

Continuous release of pollutants into the environment poses serious threats to environmental sustainability and human health. For trace-level analysis of pollutants, layered double hydroxide (LDH) is an attractive option to impart enhanced sorption capability and sensitivity toward pollutants because of its unique layered structure, tunable interior architecture, high anion-exchange capacities, and high porosity (e.g., Zn/Cr LDH/DABCO-IL, Ni/Al LDH, CS-Ni/Fe LDH, SDS-Fe₃O₄@SiO₂@Mg-Al LDH, Boeh/Mg/Al LDH/pC, and Fe@NiAl LDH). In concert with the well-defined analytical methodologies (e.g., HPLC and GC), the LDH materials can be employed to detect trace-level targets (e.g., as low as ∼ 20 fg/L for phenols) in aqueous environments. This review highlights LDH as a promising material for pre-treatment of a variety of organic and inorganic target pollutants in complex real matrices. Challenges and future requirements for research into LDH-based analytical methods are also discussed.

Recent applications of organic molecule-based framework porous materials in solid-phase microextraction for pharmaceutical analysis

Sample preparation is an indispensable part of detection of complex samples in pharmaceutical analysis. Solid-phase microextraction (SPME) has obtained a lot of attention due to its advantages of time saving, less solvent and easily automation. A variety of functional materials are used as sorbents in SPME to carry out selective and high extraction. This review centers around the recent applications of organic molecule-based framework porous materials, such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs), as SPME coating materials mainly focus on pharmaceutical analysis in food, environment, and biological samples. Four representative extraction devices are introduced, including on-fiber SPME, in-tube SPME, thin film SPME, stir bar SPME. The application prospect of other organic porous materials as sorbents for pharmaceutical analysis are also discussed, such as hyper crosslinked polymers (HCPs) and conjugated microporous polymers (CMPs). The progresses and discusses are provided to offer references for further research focusing on application and development of organic molecule-based framework porous materials in the field of SPME.

Responses of two marine fish to organically complexed Zn: Insights from microbial community and liver transcriptomics

The diversity and adjustability of metal-organic complex enhance the function of metals and promote the burgeoning fields of chemical biology. In the present study, we chose two marine fish to explore the effects of a dihydromyricetin (DMY)-Zn(II) complex on the intestinal microbiome composition and liver biological function using high-throughput sequencing technology. Two economic fish species commonly found in Southern China (golden pompano Trachinotus ovatus and pearl gentian grouper ♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus) were exposed to dietary DMY-Zn complex for 4-week. Our study found that DMY-Zn performed a vital function on the improved anti-oxidative ability of both fish species. The Zn complex improved the stability of microbial community structure of the golden pompano by enhancing the α-diversity, but its impacts on the composition and diversity of intestine microorganisms of grouper were insignificant. BugBase results showed that the intestine microbiota following DMY-Zn exposure contained a lower abundance of potentially pathogenic bacteria and higher abundance of aerobic bacteria. Intestine health and utilization of carbohydrates were improved in the golden pompano, and unclassified bacteria were significantly enriched in the grouper. Liver transcriptome indicated that DMY-Zn affected the oxidative phosphorylation process (OXPHOS). Specifically, the OXPHOS process (map00190) was activated by promoting the glucose uptake (map04251, map04010) in golden pompano and lipid metabolism (map00071, map00140, map00062 and map00564) in grouper. Such difference in the responses of intestine microbiome and liver metabolism may be possibly explained by their different Zn basal requirements. Our study demonstrated that different fish species may have different responses to dietary DMY-Zn complex. The results provided a reference for the application of new additives in aquatic animal feed, and new insights into the roles of metal-organic complex in their biological impacts on fish.

Recent advances in proteomics and metabolomics in plants

Over the past decade, systems biology and plant-omics have increasingly become the main stream in plant biology research. New developments in mass spectrometry and bioinformatics tools, and methodological schema to integrate multi-omics data have leveraged recent advances in proteomics and metabolomics. These progresses are driving a rapid evolution in the field of plant research, greatly facilitating our understanding of the mechanistic aspects of plant metabolisms and the interactions of plants with their external environment. Here, we review the recent progresses in MS-based proteomics and metabolomics tools and workflows with a special focus on their applications to plant biology research using several case studies related to mechanistic understanding of stress response, gene/protein function characterization, metabolic and signaling pathways exploration, and natural product discovery. We also present a projection concerning future perspectives in MS-based proteomics and metabolomics development including their applications to and challenges for system biology. This review is intended to provide readers with an overview of how advanced MS technology, and integrated application of proteomics and metabolomics can be used to advance plant system biology research.

Fabrication of Magnetic Al-Based Fe3O4@MIL-53 Metal Organic Framework for Capture of Multi-Pollutants Residue in Milk Followed by HPLC-UV

The efficient capture of multi-pollutant residues in food is vital for food safety monitoring. In this study, in-situ-fabricated magnetic MIL-53(Al) metal organic frameworks (MOFs), with good magnetic responsiveness, were synthesized and applied for the magnetic solid-phase extraction (MSPE) of chloramphenicol, bisphenol A, estradiol, and diethylstilbestrol. Terephthalic acid (H₂BDC) organic ligands were pre-coupled on the surface of amino-Fe₃O₄ composites (H₂BDC@Fe₃O₄). Fe₃O₄@MIL-53(Al) MOF was fabricated by in-situ hydrothermal polymerization of H₂BDC, Al (NO₃)₃, and H₂BDC@Fe₃O₄. This approach highly increased the stability of the material. The magnetic Fe₃O₄@MIL-53(Al) MOF-based MSPE was combined with high-performance liquid chromatography-photo diode array detection, to establish a novel sensitive method for analyzing multi-pollutant residues in milk. This method showed good linear correlations, in the range of 0.05–5.00 μg/mL, with good reproducibility. The limit of detection was 0.004–0.108 μg/mL. The presented method was verified using a milk sample, spiked with four pollutants, which enabled high-throughput detection and the accuracies of 88.17–107.58% confirmed its applicability, in real sample analysis.

Miniaturized green sample preparation approaches for pharmaceutical analysis

The development of green sample preparation procedures is an extremely important research field in which more and more applications are constantly being proposed in different areas, including pharmaceutical analysis. This review article is aimed at providing a general overview of the development of miniaturized green analytical sample preparation procedures in the pharmaceutical analysis field, with special focus on the works published between January 2017 and July 2021. Particular attention has been paid to the application of environmentally friendly solvents and sorbents as well as nanomaterials or high extraction capacity sorbents in which the solvent volumes and reagents amounts are drastically reduced, with their subsequent advantages from the sustainability point of view.

The Effectiveness of MOFs for the Removal of Pharmaceuticals from Aquatic Environments: A Review Focused on Antibiotics Removal

There is an increasing level of various pollutants and their persistence in aquatic environments. The improper use of antibiotics and their inefficient metabolism in organisms result in their release into aquatic environments. Antibiotic abuse has led to hazardous effects on human health. Thereby, efficient removal of pharmaceuticals, particularly antibiotics, from wastewater and contaminated water bodies is greatly interested in international research communities. Metal-organic framework (MOF) materials, as a hybrid group of material containing metallic center and organic linkers, offer a porous structure that is highly efficient for removing different pollutants from contaminated water and wastewater streams. This article aims to review the recent advancement in using MOF-based adsorbents and catalysts for the removal of pharmaceuticals, especially antibiotics, from polluted water. Applying MOFs-based structures for removing antibiotics using photocatalytic removal and adsorptive removal techniques will be discussed and evaluated in this review paper. Various MOF-based materials such as functionalized MOFs, MOF-based composites, magnetic MOF-based composites, MOFs templated-metal oxide catalysts for removing pharmaceuticals, personal care products, and antibiotics from contaminated aqueous media are discussed. Furthermore, effective operational parameters on the adsorption, adsorption mechanisms, adsorption isotherms, and thermodynamic parameters are explained and discussed. Finally, in the concluding remarks, the challenges and future outlooks of using MOFs-based adsorbents and catalysts for removing antibiotics are summarized.

Fabrication of stable multivariate metal-organic frameworks with excellent adsorption performance toward bisphenols from environmental samples

As a type of environmental endocrine disrupting chemicals, bisphenols (BPs) have a certain embryonic toxicity and teratogenicity, which can significantly increase the risks of breast cancer, prostate cancer, leukemia and other cancers. In this work, stable multivariate metal-organic frameworks (UiO-66-NH₂/TCPP_x) were synthesized via in situ one-pot method and used as miniaturized dispersive solid-phase extraction (dμSPE) sorbents for extraction of trace BPs from environmental samples. The phase purity, crystal morphology and physical properties of UiO-66-NH₂/TCPP_x samples were varied by adjusting the mass ratio of TCPP. The extraction performance of UiO-66-NH₂/TCPP_x samples were investigated and UiO-66-NH₂/TCPP_1.0 exhibited the highest adsorption efficiency. Besides, UiO-66-NH₂/TCPP_1.0 possessed excellent recycling stability for the adsorption and desorption of BPs more than 20 cycles. The experimental parameters including amount of adsorbent, adsorption time, sample solution pH, temperature, desorption time and desorption solvents which affecting the efficiency of dμSPE were studied, respectively. Good linearity (R² > 0.9992) in range of 0.1-200 ng mL^-1 was obtained. The detection limits (S/N = 3) and quantification limits (S/N = 10) were achieved at 0.03-0.08 ng mL^-1 and 0.1-0.5 ng mL^-1, respectively. The relative standard deviations (RSDs) of intra-day and inter-day ranged from 2.5 to 5.5% and 1.1-6.8%. Enrichment factors were calculated in the range of 303-338. The obtained recoveries of bisphenol F (BPF), bisphenol A (BPA), bisphenol B (BPB) and bisphenol AF (BPAF) were 81.26-91.03% (RSDs = 0.96-6.47%), 82.2-97.27% (RSDs = 0.45-6.15%), 87.56-97.26% (RSDs = 1.1-6.22%) and 82.2-100.8% (RSDs = 0.46-4.07%). The UiO-66-NH₂/TCPP_1.0 can be employed as potential dμSPE sorbents for the enrichment of trace BPs in the environmental samples.

Extraction and determination of tussilagone from Farfarae Flos with online solid-phase extraction-high-performance liquid chromatography using a homemade monolithic cartridge doped with porous organic cage material

A solid-phase extraction cartridge was fabricated using diallyl isophthalate as the monomer with the addition of porous organic cage material via in situ free-radical polymerization in a stainless-steel column. The resulting monolithic adsorbent exhibited a relatively uniform porous structure, a high specific surface area of 113.98 m² /g, and multiple functional chemical groups according to the characterization results. An online solid-phase extraction-high-performance liquid chromatography procedure was fabricated to extract and determine tussilagone from Farfarae Flos. The results show that the complex sample matrices can be removed in the solid-phase extraction procedure. Simultaneously, tussilagone can remain, which can be subsequently switched to an octadecylsilane bonded analytical column. The methodological validation showed that the correlation coefficient was 0.9999 with a linear range of 0.6-200.0 µg/mL, the limit of detection was 0.2 µg/mL, the limit of quantification was 0.6 µg/mL, accuracy was 100.3-100.6%, and relative standard deviation of precision was ≤1.9%. The present monolithic cartridge exhibits good reusability of not more than 100 times. The real sample of Farfarae Flos was determined with a tussilagone content of 0.74 mg/g.

Facile Fabrication of Diatomite-Supported ZIF-8 Composite for Solid-Phase Extraction of Benzodiazepines in Urine Samples Prior to High-Performance Liquid Chromatography

A novel diatomite-supported zeolitic imidazolate framework-8 sorbent (ZIF-8@Dt-COOH) was in situ fabricated and developed for solid-phase extraction of three benzodiazepines (triazolam, midazolam and diazepam) in urine followed by high-performance liquid chromatography. ZIF-8@Dt-COOH was easily prepared by coating ZIF-8 on the surface of Dt-COOH and characterized by Fourier transform infrared spectra, X-ray powder diffractometry and scanning electron microscopy. Compared with bare Dt-COOH, the extraction efficiency of ZIF-8@Dt-COOH for the target was significantly increased from 20.1–39.0% to 100%. Main extraction parameters, including ionic strength and pH of solution, loading volume, washing solution, elution solvent and elution volume, were optimized in detail. Under optimum conditions, the developed method gave linearity of three BZDs in 2–500 ng/mL (r ≥ 0.9995). Limits of detection (S/N = 3), and limits of quantification (S/N = 10) were 0.3–0.4 ng/mL and 1.0–1.3 ng/mL, respectively. In addition, the average recoveries at three spiked levels (5, 10 and 20 ng/mL) varied from 80.0% to 98.7%, with the intra-day and inter-day precisions of 1.4–5.2% and 1.5–8.2%, respectively. The proposed method provided an effective purification performance and gave the enrichment factors of 24.0–29.6. The proposed method was successfully employed for the accurate and sensitive determination of benzodiazepines in urine.

A molecularly imprinted polymer based on MOF and deep eutectic solvent for selective recognition and adsorption of bovine hemoglobin

In this study, a novel kind of imprinted polymers based on metal-organic frameworks (MOF@DES-MIPs) was prepared, using bovine hemoglobin (BHb) as template molecules and deep eutectic solvents (DES) as functional monomers for selective recognition and adsorption of BHb. MOF were used as the substrates to improve the accessibility of imprinted sites and DES as the functional monomers to produce different forces for BHb to help the formation of imprinted sites. Imprinted polymer films were taken to provide analyte selectivity. The MOF@DES-MIPs prepared were characterized and evaluated by scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectrometer. We also investigated the influences of BHb concentration and adsorption time on the performance of MOF@DES-MIPs. The maximal adsorption capacity of MOF@DES-MIPs to BHb reached 151.28 mg g^-1, and the MOF@DES-MIPs showed good selectivity and fast adsorption equilibrium, which might offer a novel method for the preparation and research of molecularly imprinted polymers of biomacromolecules. In addition, MOF@DES-MIPs were successfully applied in the selective recognition of BHb from a real bovine blood sample. Graphical abstract.

Novel Fe3O4@metal-organic framework@polymer core-shell-shell nanospheres for fast extraction and specific preconcentration of nine organophosphorus pesticides from complex matrices

Herein, a novel core-shell-shell magnetic nanosphere denoted as Fe₃O₄@ZIF-8@polymer was fabricated by sequential in situ self-assembly and precipitation polymerization for effective magnetic solid-phase extraction of nine organophosphorus pesticides (OPPs) from river water, pear, and cabbage samples. The integrated Fe₃O₄@ZIF-8@polymer featured convenient magnetic separation property and excellent multi-target binding ability. More importantly, the functional polymer coating greatly improved the extraction performance of Fe₃O₄@ZIF-8 for OPPs, thus facilitating the simultaneous determination of trace OPP residues in real samples. The developed MPSE-LC-MS/MS method exhibited good linearity (R² ≥ 0.9991) over the concentration range of 0.2-200 µg L^-1, low limits of detection of 0.0002-0.005 μg L^-1 for river water and 0.006-0.185 μg kg^-1 for pear and cabbage, satisfactory precision with relative standard deviations ≤ 9.7% and accuracy with recoveries of 69.5-94.3%. These results highlight that the combination of polymers with MOFs has great potential to fabricate excellent adsorbents for high-throughput analysis of various contaminants in complex matrices.

Series of highly stable Cd(ii)-based MOFs as sensitive and selective sensors for detection of nitrofuran antibiotic

The oxygen atom of the MOF ether-bridging group acts as a Lewis base site, improving the connection and allowing the detection of 10 antibiotics through the fluorescence quenching effect.

Fabrication of edge-curled petals-like covalent organic frameworks and their properties for extracting indole alkaloids from complex biological samples

In this study, a functionalized covalent-organic framework (COF) was first synthesized using porphyrin as the fabrication unit and showed an edge-curled, petal-like and well-ordered structure. The synthesized COF was then introduced to prepare porous organic polymer monolithic materials (POPMs). Two composite POPM/COF monolithic materials with rod shapes, referred to as sorbent A and sorbent B, were prepared in stainless steel tubes using different monomers. Sorbents A and B exhibited relatively uniform porous structures and enhanced specific surface areas of 153.14 m²/g and 80.01 m²/g, respectively. The prepared composite monoliths were used as in-tube solid-phase extraction (SPE) sorbents combined with HPLC for the on-line extraction and quantitative analytical systems. Indole alkaloids (from Catharanthus roseus G. Don and Uncaria rhynchophylla (Miq.) Miq. Ex Havil.) contained in mouse plasma were extracted and quantitatively analyzed using the online system. The two composite multifunctional monoliths showed excellent clean-up ability for complex biological matrices, as well as superior selectivity for target indole alkaloids. Method validation showed that the RSD values of the repeatability (n=6) were ≤ 3.46%, and the accuracy expressed by the spiked recoveries was in the ranges of 99.38%–100.91% and 96.39%–103.50% for vinca alkaloids and Uncaria alkaloids, respectively. Furthermore, sorbents A and B exhibited strong reusability, with RSD values ≤ 5.32%, which were based on the peak area of the corresponding alkaloids with more than 100 injections. These results indicate that the composite POPM/COF rod-shaped monoliths are promising media as SPE sorbents for extracting trace compounds in complex biological samples.

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Edge-curled petals-like COF was synthesized using porphyrin as the fabrication unit.

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In-tube monolithic POMP/COF composite SPE sorbents with rod-shape were fabricated.

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The in-tube sorbents were used to extract hence indole alkaloids from complex samples.

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The two homemade sorbents show strong reusability of more than 100 times.

Synthesis of Magnetic Metal-Organic Frame Material and Its Application in Food Sample Preparation

A variety of contaminants in food is an important aspect affecting food safety. Due to the presence of its trace amounts and the complexity of food matrix, it is very difficult to effectively separate and accurately detect them. The magnetic metal-organic framework (MMOF) composites with different structures and functions provide a new choice for the purification of food matrix and enrichment of trace targets, thus providing a new direction for the development of new technologies in food safety detection with high sensitivity and efficiency. The MOF materials composed of inorganic subunits and organic ligands have the advantages of regular pore structure, large specific surface area and good stability, which have been thoroughly studied in the pretreatment of complex food samples. MMOF materials combined different MOF materials with various magnetic nanoparticles, adding magnetic characteristics to the advantages of MOF materials, which are in terms of material selectivity, biocompatibility, easy operation and repeatability. Combined with solid phase extraction (SPE) technique, MMOF materials have been widely used in the food pretreatment. This article introduced the new preparation strategies of different MMOF materials, systematically summarizes their applications as SPE adsorbents in the pretreatment of food contaminants and analyzes and prospects their future application prospects and development directions.

Recent Advances in Affinity MOF-Based Sorbents with Sample Preparation Purposes

This review summarizes the recent advances concerning metal-organic frameworks (MOFs) modified with several biomolecules (e.g., amino acids, nucleobases, proteins, antibodies, aptamers, etc.) as ligands to prepare affinity-based sorbents for application in the sample preparation field. The preparation and incorporation strategies of these MOF-based affinity materials were described. Additionally, the different types of ligands that can be employed for the synthesis of these biocomposites and their application as sorbents for the selective extraction of molecules and clean-up of complex real samples is reported. The most important features of the developed biocomposites will be discussed throughout the text in different sections, and several examples will be also commented on in detail.

Structural analysis of and selective CO2 adsorption in mixed-ligand hydroxamate-based metal-organic frameworks

Two mixed-ligand metal-organic frameworks, [Zn₂(BDHA)_0.5(INA)₃] (MOF-1: H₂BDHA = benzene-1,4-dihydroxamic acid; HINA = isonicotinic acid) and [Co₂(BDHA)_0.5(INA)₃(DMF)] (MOF-2), were solvothermally synthesized and fully characterized by single-crystal X-ray crystallography as well as N₂, H₂, and CO₂ gas-sorption measurements. The results constitute the first detailed analysis of the bonding environment around the hydroxamates in such MOFs, which are simultaneously decorated with Lewis-basic sites from the hydroxamate moieties and metal sites predisposed for coordinative unsaturation. MOF-2 shows a desirably selective adsorption of CO₂ relative to N₂.

Role of Ionic Liquids in Composites in Analytical Sample Preparation

Ionic liquids (ILs) are a group of non-conventional salts with melting points below 100 °C. Apart from their negligible vapor pressure at room temperature, high thermal stability, and impressive solvation properties, ILs are characterized by their tunability. Given such nearly infinite combinations of cations and anions, and the easy modification of their structures, ILs with specific properties can be synthesized. These characteristics have attracted attention regarding their use as extraction phases in analytical sample preparation methods, particularly in liquid-phase extraction methods. Given the liquid nature of most common ILs, their incorporation in analytical sample preparation methods using solid sorbents requires the preparation of solid derivatives, such as polymeric ILs, or the combination of ILs with other materials to prepare solid IL-based composites. In this sense, many solid composites based on ILs have been prepared with improved features, including magnetic particles, carbonaceous materials, polymers, silica materials, and metal-organic frameworks, as additional materials forming the composites. This review aims to give an overview on the preparation and applications of IL-based composites in analytical sample preparation in the period 2017–2020, paying attention to the role of the IL material in those composites to understand the effect of the individual components in the sorbent.

Covalent organic frameworks-based paper solid phase microextraction combined with paper spray mass spectrometry for highly enhanced analysis of tetrabromobisphenol A

COFs-based paper solid phase microextraction-paper spray mass spectrometry was developed for tetrabromobisphenol A detection with enhanced analysis performance.