Ferrocene-based nanoporous organic polymer as solid-phase extraction sorbent for the extraction of chlorophenols from tap water, tea drink and peach juice samples

Recent advances in synthesis and applications of hyper-crosslinked porous organic polymers for sample pretreatment: A review

Hyper-crosslinked porous organic polymers (HCPs) are nanoporous materials synthesized through Friedel-Crafts reactions, which covalently crosslink monomeric units to integrate the high porosity, large surface area, and tunable pore architecture of porous networks with the structural diversity, lightweight nature, and compositional flexibility inherent to polymeric systems. These materials exhibit excellent thermal/chemical stability, facile surface functionalization, and scalable synthesis protocols, enabling versatile applications in drug delivery, chromatography, catalysis, and gas storage. In recent years, HCPs have gained prominence as advanced sorbents in sample pretreatment, owing to their inherent physicochemical characteristics that align closely with the critical requirements for high-performance extraction or purification adsorbents. This review aims to present recent advancements in HCPs preparation, with a primary focus on their applications in analytical sample preparation. A systematic investigation of HCP-based adsorption mechanisms, structural design principles, and fabrication methodologies was conducted to establish robust structure-function correlations through performance evaluation across diverse extraction techniques, including column solid-phase extraction (SPE), magnetic SPE (MSPE), solid-phase microextraction (SPME), and other miniaturized SPE formats, for the pre-concentration of target analytes in food, environmental, and biological samples. Finally, we delineate current challenges and future research directions, proposing innovative engineering strategies to advance HCPs for addressing complex analytical matrix challenges.

Construction of carboxyl-functionalized hyper-cross-linked porous polymers using waste polystyrene for effective adsorption of phenolic contaminants

The extensive presence of phenolic organic contaminants (POCs) poses a serious threat to humans. Meanwhile, the upcycling/reusing of waste polystyrene to reduce the exponential growth of plastic pollution is a very important environmental issue. Addressing these demands, a series of carboxyl-functional hypercrosslinked polymers (labeled PP-HCPs) were constructed by knitting waste polystyrene with pyromellitic dianhydride at different ratios through a one-step Friedel-Crafts reaction for effective adsorption of POCs. Among the prepared PP-HCPs, PP-HCP2 displayed a large specific surface area with high adsorption capacity (37.3 mg g-1) for POCs. Using PP-HCP2 as solid phase extraction sorbent, six POCs were effectively extracted from water and peach drink samples, then subjected to high-performance liquid chromatography-ultraviolet detection. The method demonstrated good linearity in the range of 0.03-100.0 ng mL-1 for water samples and 0.06-100.0 ng mL-1 for peach drinks under optimum experimental conditions. At a signal-to-noise ratio of 3, low detection limits were found to be 0.01-0.10 ng mL-1 for water samples and 0.02-0.15 ng mL-1 for peach drinks. Good accuracy and repeatability were achieved with recoveries of 85.3-111.8 % and the relative standard deviations below 8.6 %. The PP-HCP2-based approach can be employed as a dependable and sensitive tool to detect POCs in water and peach drink samples. This work delivers a simple and economically viable approach to fabricate carboxyl-functional HCPs by converting waste foam into high-value-added sorbent, with great significance for sustainable development.

Chlorophenols in environment: Recent updates on pretreatment and analysis methods

Chlorophenols (CPs) are widely used in industries such as petrochemicals, insecticides, pharmaceuticals, synthetic dyes and wood preservatives. However, owing to the improper discharge and disposal, they have become major contaminants that are ubiquitously distributed in water, soil, and sewage sediments, posing a significant threat to ecosystems and human health. Consequently, accurate, sensitive and effective pretreatment and analysis methods for CPs are urgently required and have been actively explored in recent years. This review encompasses the pretreatment and detection methods for CPs in environmental samples from 2010 to 2024. The pretreatment methods for CPs primarily include solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, liquid-phase microextraction, and QuEChERS. These methods are evolving towards more effective and environmentally friendly technologies, such as the miniaturization and automation of equipment, the development of innovative materials (including graphene, molecularly imprinted polymers, layered double hydroxides, porous organic polymers, and porous carbon), and the use of green solvents like deep eutectic solvents. Detection methods emphasize liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, sensors, and capillary electrophoresis. Advances in chromatographic columns, novel ion sources, and high-resolution mass spectrometry have significantly improved detection performance. In addition, the pros and cons of diverse techniques, critical comments and future perspectives are elaborated.

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

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

Electrodeposited histidine-(CuCr)layered double hydroxides/carbon dots for in-tube solid-phase microextraction of chlorophenols from water, juice, and honey samples followed by HPLC-UV

A novel adsorbent consisting of a composition of carbon dots and CuCr-layered double hydroxides intercalated with l-histidine (C-dots@His/LDHs) was introduced. This adsorbent was electrochemically deposited on the inner surface of a capillary copper tube. It was used as an adsorbent for in-tube solid-phase microextraction of chlorophenols (CPs). Separation and measurement of CPs were done by high-performance liquid chromatography-ultraviolet detector. The main parameters which had the most impact on the extraction efficiency and time such as extraction time and flow rate, desorption time and flow rate, ionic strength (salt concentration) and pH were optimized. Calibration curves (0.5-1000 μg L-1) were plotted in real sample (tap water) under optimal conditions which coefficients of determination better than 0.9893 and relative recoveries in the range of 88-120 % were obtained. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were obtained in the range of 0.1-1.0 μg L-1 and 0.3-3.0 μg L-1, respectively. The intra- and inter-assay precisions (RSD%, n = 3) were better than 5.9 and 8.8 %, respectively.

One-step preparation of carboxyl-functionalized porous organic polymer as sorbent for enrichment of phenols in bottled water, juice and honey samples

Herein, a novel carboxyl-functionalized porous organic polymer (COOH-POP) was prepared as sorbent. Due to multiple hydrogen bonds and π-π interactions between COOH-POP and phenols, COOH-POP shows good enrichment ability and very fast adsorption rate for phenols. Then, an analytical method was developed for determination of five phenols (2-chlorophenol, bisphenol A, 2,6-dichlorophenol, 2,4-dichlorophenol and p-tert-butylphenol) in bottled water, lemon juice, peach juice and honey samples using COOH-POP as solid phase extraction sorbent in combination with high performance liquid chromatography. Under optimal conditions, the COOH-POP based method gave the detection limits (S/N = 3) of 0.02-0.10 ng mL-1 for bottled water, 0.03-0.12 ng mL-1 for lemon juice, 0.03-0.25 ng mL-1 for peach juice and 0.7-1.5 ng g-1 for honey samples. The recoveries for spiked samples ranged from 84.0 % to 119.0 % with relative standard deviation less than 7.6 %. This study provides a new yet effective method for enrichment of phenols by designing carboxyl-functionalized porous organic polymer as sorbent.

Research progress of the combination of COFs materials with food safety detection

Covalent organic frameworks (COFs) have received lots of attention due to their multiple advantages such as high specific surface area, controlled pore size, and excellent stability. When detecting food contaminants, the matrix effect brought by complex food samples can significantly affect the accuracy of the results. How to attenuate matrix effect has always been a major challenge. Utilizing the advantages of COFs and applying them to detect food contaminants is currently a key research direction. The aim of this work is to provide a systematic summary of sample pretreatment techniques and detection techniques combined with COFs, which include almost all current techniques combined with COFs. In addition, the principles of combining COFs with different techniques are explained. Finally, the research foci and development direction of COFs in food contaminant detection are discussed. This is an important reference for the future development of food safety and the design of COFs.

N-rich hypercrosslinked porous polymers for highly efficient preconcentration and sensitive detection of chlorophenols

Three novel N-rich hypercrosslinked porous polymers (NHCP1, NHCP2, and NHCP3) were facilely developed using Friedel-Crafts alkylation. NHCP1 with a remarkably large surface area (2066 m² g^-1) showed the best adsorption performance for chlorophenol pollutants. A sensitive and simple method was developed by using NHCP1 as a sorbent for solid-phase extraction to preconcentrate several chlorophenols in honey, water, and peach beverage samples followed by determination using a high-performance liquid chromatography-ultraviolet detector. The detection wavelength was 280 nm. Under the optimized conditions, the linear ranges were 1.67-1000 ng g^-1 for honey, 0.170-100 ng mL^-1 for water, and 0.330-100 ng mL^-1 for peach beverage samples. The detection limits (S/N = 3) were 0.500-2.00 ng g^-1, 0.0500-0.100 ng mL^-1, and 0.100-0.200 ng mL^-1, respectively. Recovery values were 89.3-111% with relative standard deviations <9.4%. The proposed extraction/preconcentration and quantitative analysis method provides an affordable and effective alternative for the preconcentration and determination of low levels of chlorophenols in real samples.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (H₃PW₁₂O₄₀). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME). The method was used for the extraction of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6- trichlorophenol from tap water, river water, and tea sample. The extracted target analytes were quantified via high-performance liquid chromatography-UV detection. The figures of merit of the method such as, linear dynamic ranges (LDRs), limit of detections (LODs) and, limit of quantifications (LOQs), were determined based on the obtained optimum condition. Based on the results, the LDR was between 1 and 500 μg L ^- 1 and r² higher than 0.9960. The LODs and LOQs were obtained in the ranges of 0.28-0.36 µg L ^- 1 and 0.92-1.1 µg L ^- 1, respectively. The relative standard deviations ((RSDs% for inter-and intra-day) of the method for the extraction of target analytes were calculated in two different concentrations of (2 and 10 μg L ^- 1) and (5 and 10 μg L ^- 1) between 3.70% - 5.30% and 3.50% - 5.70%-respectively. The enrichment factors were obtained between 57 and 61. In order to investigate the accuracy of the method, also the relative recovery was obtained, between 93 and 105%. Finally, the proposed method was used for the extraction of the selected analytes in different water and tea samples.

Porous agarose/chitosan/graphene oxide composite coupled with deep eutectic solvent for thin film microextraction of chlorophenols

In this project, a three-dimensional graphene oxide coated agarose/chitosan (ACGO) porous film was synthesized and utilized as sorbent in thin film microextraction (TFME) technique to extract 4-chlorophenol, 2,4-dichlorophenol, 3,5-dichlorophenol and 2,4,6-trichlorophenol as the model analytes in various real samples such as agricultural waste water, honey and tea samples. In addition, deep eutectic solvent made of tetra ethyl ammonium chloride/chlorine chloride was used as a desorption solvent. The effect of various variables, such as: extraction time, stirring rate, solvent desorption volume, desorption time, ionic strength and solution pH on the extraction efficiency of the method was studied and optimized. Under the optimized condition, the linear range of the method was obtained in the range of 0.1-500μgL^-1 for testing analytes (4-chloropheol=0.1-500μgL^-1, 2,4-dichlorophenol=0.2-500μgL^-1, 3,5-dichlorophenol=0.5-500μgL^-1 and 2,4,6-trichlorophenol=0.2-500μgL^-1). The obtained correlation coefficients (r²) were between 0.9984 and 0.9994. The limits of detection (LODs) were also calculated between 0.03 - 0.13μgL^-1. The relative standard deviations (RSDs%) were obtained in the range of 2.8 to 5.9%. The enrichment factor (EFs) values for the studied analytes were also obtained in the range of 33.4-35.8. In addition, the obtained results indicated that the prepared film can potentially be used for more applications in the field of environment, food safety, and drug analysis.

Facile synthesis of hypercrosslinked polymer as high-efficiency adsorbent for the enrichment of nitroimidazoles from water, honey and chicken meat

Design and fabrication of functionalized hypercrosslinked polymers (HCPs) for enhancing their performance by using green renewable monomers has attracted considerable research interest. In this study, hydroxyl‑functional HCP (labeled as OHHCP) was prepared via the knitting method by applying natural naringenin as a monomer for the first time. Due to the good hydrophilicity and strong H-bonding ability, the OHHCP showed high extraction capacity for nitroimidazoles. Thus, it was successfully applied as a potent adsorbent for solid phase extraction of five nitroimidazoles in water, honey and chicken meat, followed by high-performance liquid chromatography-diode array detector analysis. At the optimized conditions, the limit of detections (S/N = 3) of the proposed method for water, honey and chicken samples were 0.02 - 0.06 ng mL^-1, 0.5 - 1.0 ng g^-1 and 0.8 - 1.0 ng g^-1, respectively. The recoveries were 80.0 - 110%, and the relative standard deviations were below 10.0%. The OHHCP also displayed good application prospects for other organic compounds with H-bonding capability. This study highlights the facile preparation of OH-functionalized HCPs from renewable and natural resources as potent adsorbents for polar compounds.

Facile fabrication of hydroxyl-functionalized hypercrosslinked polymer for sensitive determination of chlorophenols

Three hydroxyl-functionalized hypercrosslinked polymers (HCP-POL, HCP-HQ and HCP-PG) were synthesized by Friedel-Crafts reaction. The HCP-HQ displayed the largest surface area and highest adsorption capacity for chlorophenols (CPs). Thus, the HCP-HQ was further modified with magnetism to obtain M-HCP-HQ. An efficient magnetic solid-phase extraction method with M-HCP-HQ as adsorbent was developed for the first time to simultaneously extract four CPs from water and honey samples before analysis by high performance liquid chromatography-diode array detection. Under optimized conditions, the low detection limits (S/N = 3) were obtained to be 0.06-0.10 ng mL^-1 for water and 0.80-1.75 ng g^-1 for honey. The method recovery was 80.7%-119%, with relative standard deviations below 9.5%. The enrichment factors of the CPs were in the range of 57-220. The extraction mechanism could be attributed to the strong polar interaction, hydrogen bonding and π-π interactions between the M-HCP-HQ and CPs. The M-HCP-HQ based method can be served as a reliable and sensitive tool for detection CPs in water and honey samples.

Synthesis of natural proanthocyanidin based novel magnetic nanoporous organic polymer as advanced sorbent for neonicotinoid insecticides

In this work, a natural proanthocyanidin (PA) based magnetic nanoporous organic polymer (named as PA-MOP) was successfully synthesized for the first time. The PA-MOP possessed high hydrophilic-surface, good magnetic responsiveness and high affinity for neonicotinoid insecticides. It was applied as an advanced magnetic sorbent for extraction of four neonicotinoids (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) from environmental water, peach juice and honey samples prior to HPLC analysis. Under optimal conditions, the limits of detection for the analytes at S/N = 3 were 0.02-0.08 ng mL^-1 for water, 0.03-0.10 ng mL^-1 for peach juice and 0.05-0.16 ng g^-1 for honey sample. The method recoveries were 80.0%-114.8%, with the relative standard deviations below 6.8%. The values of matrix effect were from -1.5% to -9.3%. Based on theory calculation, the extraction mechanism can be attributed to multiple interactions between the PA-MOP and the neonicotinoids, in which hydrogen bonding, π-π stacking and electrostatic interactions are the major interactions.

Porous Organic Polymers Derived from Ferrocene and Tetrahedral Silicon-Centered Monomers for Carbon Dioxide Sorption

Herein, we present two novel ferrocene-containing porous organic polymers, FPOP-1 and FPOP-2, by the Heck reactions of 1,1'-divinylferrocene with two tetrahedral silicon-centered units, i.e., tetrakis(4-bromophenyl)silane and tetrakis(4'-bromo-[1,1'-biphenyl]-4-yl)silane. The resulting materials possess high thermal stability and moderate porosity with the Brunauer-Emmer-Teller (BET) surface areas of 499 m2 g-1 (FPOP-1) and 354 m2 g-1 (FPOP-2) and total pore volumes of 0.43 cm3 g-1 (FPOP-1) and 0.49 cm3 g-1 (FPOP-2). The porosity is comparable to previously reported ferrocene-containing porous polymers. These materials possess comparable CO2 capacities of 1.16 mmol g-1 (5.10 wt%) at 273 K and 1.0 bar, and 0.54 mmol g-1 (2.38 wt%) at 298 K and 1.0 bar (FPOP-1). The found capacities are comparable to, or higher than many porous polymers having similar or higher surface areas. They have high isosteric heats of up to 32.9 kJ mol-1, proving that the affinity between the polymer network and CO2 is high, which can be explained by the presence of ferrocene units in the porous networks. These results indicate that these materials can be promisingly utilized as candidates for the storage or capture of CO2. More ferrocene-containing porous polymers can be designed and synthesized by combining ferrocene units with various aromatic monomers under this strategy and their applications could be explored.

Fabrication of carbonyl-functional hypercrosslinked polymers as solid-phase extraction sorbent for enrichment of chlorophenols from water, honey and beverage samples

Three carbonyl-functional novel hypercrosslinked polymers (HCP-TPS, HCP-TPA, and HCP-TPP) were successfully fabricated through an one-step Friedel-Crafts acylation reaction by copolymerizing paraphthaloyl chloride with triphenylsilane, triphenylamine, and triphenylphosphine, respectively. The resultant HCPs contained plenty of carbonyl-functional groups. Among the series of such HCPs, HCP-TPS displayed the best adsorption capability to chlorophenols (CPs), and thus it was employed as solid-phase extraction (SPE) adsorbent for enrichment of chlorophenols from water, honey, and white peach beverage prior to determination by high-performance liquid chromatography. Under the optimal conditions, the detection limits of the method (S/N = 3) were 0.15-0.3 ng mL^-1 for tap water and leak water, 2.5-6.0 ng g^-1 for honey sample and 0.4-0.6 ng mL^-1 for white peach beverage sample. The recoveries of CPs in the spiked water, honey samples, and white peach beverage were in the range of 89.0-108.4%, 81.4-118.2%, and 85.0-113.5%, respectively. This work provides a new strategy for constructing functionalized HCPs as efficient SPE adsorbents. In this work, three novel hypercrosslinked polymers (HCPs) were synthesized by the Friedel-Crafts alkylation reaction (paraphthaloyl chloride as the alkylating agent, triphenylsilane, triphenylamine, and triphenylphosphine as the aromatic units). Then, HCP-TPS was applied to soild-phase extraction sorbent for enrichment CPs from water, honey, and white peach beverage samples.

Construction of imine-linked covalent organic framework as advanced adsorbent for the sensitive determination of chlorophenols

Food safety is a great concern of the general public. Chlorophenols (CPs) as organic pollutant can be found in drinking water and foods, causing serious harm to human health. Herein, imine-linked covalent organic frameworks (COFs), named as TAPT-AN-COF, was synthesized by aniline modulation strategy through condensation of 1,3,5-triformylphoroglucinol and 4,4',4''-(1,3,5-Triazine-2,4,6-triyl)trianiline with aniline as modulator. The prepared TAPT-AN-COF possesses good crystallinity and regular morphology, displaying excellent adsorption capability towards CPs pollutants. Thus, the TAPT-AN-COF was used as novel adsorbent for off-line solid-phase extraction of four CPs (2-CP, 3-CP, 2,3-CPs, 2,4-CPs) from bottled water, tea drink and honey samples before high performance liquid chromatography-ultraviolet detection. Under optimal conditions, wide linear range, low detection limits and satisfactory extraction recovery were gained. The π-stacking and hydrophobic interactions between the TAPT-AN-COF and the analytes played an important role in the adsorption. The established method has a great potential in determining other hydrophobic aromatic compounds.

Template-directed synthesis of zeolitic imidazolate framework-8 derived Zn-Al layered double oxides decorated on the electrochemically anodized nanoporous aluminum substrate for thin film microextraction of chlorophenols followed by determination with high-performance liquid chromatography

In this work, hierarchical ZIF-8 coated anodized aluminum foil was prepared through in situ template-directed method without addition of any zinc salt. The hierarchical sorbent was synthesized by the formation of the final HZIF-8 on the previously created layered double oxide (LDO) template. The LDO template was created by calcining the firstly in situ prepared desired layered double hydroxide (LDH) precursor coated on the electrochemically anodized porous Al foil in an air atmosphere. The microextraction ability of the extracting device was studied through direct immersion thin film microextraction (DI-TFME). The extracted analytes were quantified by high-performance liquid chromatography equipped by UV detector (HPLC-UV). The present strategy was used for the simultaneous extraction and quantification of four selected chlorophenols (CPs) (as model analyte). The variables of the TFME were optimized using response surface methodology (Plackett-Burman and Box-Behnken design). Under the obtained optimum condition, the prepared film presented acceptable extraction properties including low limits of detection (0.03-0.22 µgL^-1), good linear ranges (0.2-200 µgL^-1, r² > 0.9918) and satisfactory reproducibility (relative standard deviation, 3.6 < RSD < 5.8% for one film as inter- and intra-day RSD, 4.8 < RSD < 5.3% for film to film). Moreover, the obtained enrichment factors were in the range of 56-76. The kinetics and adsorption isotherm of the selected analytes adsorption to the prepared sorbent were also investigated. The maximum adsorption capacities of the selected analytes on the prepared sorbent were in the range of 26.4-80.1 mg g^-1. The adsorption isotherm obeyed the Langmuir and Freundlich models. Moreover, the adsorption of the selected chlorophenols on the prepared film followed the pseudo-second-order kinetic model. Finally, the HZIF-8 film was utilized for the quantification of selected CPs in different types of water and wastewater samples. The results showed satisfactory relative recoveries (93-102%) and acceptable precisions (3.6 < RSD < 9.2%).

Magnetic solid-phase extraction using polydopamine-coated magnetic multiwalled carbon nanotube composites coupled with high performance liquid chromatography for the determination of chlorophenols

Polydopamine (PDA)-coated magnetic multiwalled carbon nanotube (M-MWCNT) composites were synthesized in two facile preparation steps, and were used as adsorbents for magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography (HPLC) for simultaneous extraction, enrichment and determination of five kinds of typical chlorophenols (CPs) in water samples. The as-prepared magnetic composites showed excellent magnetic properties and high thermal stability. Various main parameters influencing the extraction efficiency of MSPE were systematically investigated. Under the optimized MSPE-HPLC conditions, a high enrichment factor (EF) was obtained in the range of 85-112 for 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,6-dichlorophenol (2,6-DCP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP). Good linearity was obtained in the range of 2.0-200 μg L^-1 for 2-CP and 4-CP and 1.0-200 μg L^-1 for 2,6-DCP, 2,4-DCP and 2,4,6-TCP, with a correlation coefficient (R²) higher than 0.9964. The limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.10-0.31 μg L^-1 and 0.35-1.03 μg L^-1, respectively. The intraday and interday precisions evaluated using relative standard deviation (RSD) values were in the range of 1.05-2.25% and 1.88-2.83%, respectively. The validated MSPE-HPLC method was also successfully applied to analyze five kinds of CPs in tap water, lake water, river water and seawater samples, and satisfactory recoveries were obtained in the range of 76.87-106.5% with RSDs of 1.64-6.78%.

Zeolitic imidazolate framework-8/ fluorinated graphene coated SiO2 composites for pipette tip solid-phase extraction of chlorophenols in environmental and food samples

In this work, a novel composite adsorbent was successfully prepared by zeolite imidazolate framework-8/fluorinated graphene layer-by-layer covalently bonded on SiO₂ microspheres, and followed to be packed into micro pipette tip for extraction of trace chlorophenols prior to their detection by high performance liquid chromatography (HPLC). The morphology and structure of adsorbent material was characterized by field emission scanning electron microscopy with energy dispersive spectrometer, X-ray diffraction, and N₂ adsorption. The parameters including the amount of adsorbent, sampling volume, sampling rate, sample pH, and desorption solvent affected the extraction performance was systematically investigated by pipette tip solid-phase extraction (PT-SPE) coupled with HPLC analysis. Under the optimized condition, the linearity of this method ranged from 20 to 2000 ng mL^-1 for chlorophenols (CPs) with determination coefficient higher than 0.99. The limit of detection (at a signal-to-noise ratio of 3) were in the range 2-20 ng mL^-1 for tap water and black tea drinks, 0.2-2 μg g^-1 for honey. The relative recoveries of the CPs from spiked samples ranged from 71.8% to 104.7%, with relative standard deviations less than 6.2%. The filled extraction tube exhibited good stability and reproducibility. The proposed method has been successfully used to detect CPs in water and drinks with satisfactory recoveries.

The Role of Suspension Array Technology in Rapid Detection of Foodborne Pollutants: Applications and Future Challenges

Food safety is an important livelihood issue, which has always been focused attention by countries and governments all over the world. As food supply chains are becoming global, food quality control is essential for consumer protection as well as for the food industry. In recent years, a great part of food analysis is carried out using new techniques for rapid detection. As the first biochip technology that has been approved by the Food and Drug Administration (FDA), there is an increasing interest in suspension array technology (SAT) for food and environmental analysis with advantages of rapidity, high accuracy, sensitivity, and throughput. Therefore, it is important for researchers to understand the development and application of this technology in food industry. Herein, we summarized the principle and composition of SAT and its application in food safety monitoring. The utility of SAT in detection of foodborne microorganisms, residues of agricultural and veterinary drugs, genetically modified food and allergens in recent years is elaborated, and the further development direction of SAT is envisaged.

Monolithic mixed matrix membrane based on polyethersulfone/functionalized MWCNTs nanocomposite as an SPME fiber: Application to extract chlorophenols from human urine and serum samples followed by GC-ECD

A monolithic mixed matrix membrane of functionalized multi-walled carbon nanotubes-polyethersulfone (MWCNT/PES) was prepared in a non-covalent approach and employed as an SPME fiber for extraction of chlorophenols (CPs). The proposed extraction method was followed by GC-ECD to determine the analytes. The influencing factors on the extraction efficiency such as pH, ionic strength, extraction and desorption temperature and time were studied. Under the selected conditions, calibration curves were linear over a wide concentration range from 0.005 to 1000 µgL^-1 (r² > 0.9961) for target analytes. In addition, the limits of detection (LOD) of the method were obtained in the range of 0.3-30 ng L^-1. The relative standard deviation (RSD) for single fiber repeatability (n = 5) is from 1.4 to 4.6%. Fiber-to-fiber repeatability (n = 3) was also evaluated and the RSD is in the range of 1.3-6.3%. Applications of proposed fiber for extraction of CPs from the headspace of urine and serum samples were successfully investigated. The relative recovery in the biological samples spiked with different levels of CPs were in the range of 91.6-102.5%.

Highly Sensitive Determination of 2,4,6-Trichlorophenol by Using a Novel SiO2@MIPIL Fluorescence Sensor with a Double Recognition Functional Monomer

A novel SiO₂@ MIPIL fluorescence sensor for the highly sensitive detection of 2,4,6-trichlorophenol was prepared by using surface molecularly imprinting technology with SiO₂ microspheres as carriers and 3,3'-(anthracene-9,10-diylbis(methylene))bis(1-vinyl-1H-imidazole-3-ium) chloride as a double recognition fluorescence functional monomer. The prepared molecularly imprinted polymer (SiO₂@MIPIL) was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, laser confocal microscopy, and nuclear magnetic resonance. Compared with the polymer obtained via bulk polymerization (MIPIL), the surface molecularly imprinted polymer (SiO₂@MIPIL) has a better linear range (0.1-50 nM), lower detection limit (89 pM), and shorter detection time (approximately 1.5 min). The fluorescence sensor also shows good specificity, high sensitivity, good stability, and reusability. Satisfactory results were obtained when using this sensor in industrial wastewater and spiked environmental water.

Layered porous organic frameworks as a novel adsorbent for the solid phase extraction of chlorophenols prior to their determination by HPLC-DAD

A layered porous organic framework (L-POF) with high surface area and porous volume was used as a novel adsorbent for adsorption of chlorophenols (CPs). The L-POF showed much higher adsorption capacity for four CPs (2-CP, 3-CP, 2,3-CP, 2,4-CP) compared with corresponding amorphous POF and some commercial adsorbents. Then, an L-POF-based solid-phase extraction method combined with high-performance liquid chromatography for analyzing CPs at the wavelength of 280 nm in water and honey samples was established. Under the optimum conditions, four CPs exhibited good linearity in the range 0.10-80.0 ng mL^-1 for water and 2-400 ng g^-1 for honey samples with determination coefficient r² > 0.996. The method has low limits of detection of 0.03-0.10 ng mL^-1 for water and 0.5-1.0 ng g^-1 for honey samples. The method presented satisfactory precision and accuracy with relative standard deviations ≤ 7.8% and recoveries of 80-115%. High enrichment factors of 123-190 for water and 63-97 for honey were obtained. The validated method was successfully used to determine CPs in water and honey samples. The L-POF also displayed prominent adsorption performance for many other dyes and organic contaminants. This suggests that it can be an ideal candidate as adsorbent for wide application in separation and analysis. Graphical Abstract.

Preparation of a Magnetic Nanoporous Polymer for the Fast and Efficient Extraction of 5-Nitroimidazoles in Milk

A magnetic nanoporous organic polymer (M-NOP) was prepared as a new adsorbent with excellent extraction capacity and rapid adsorption kinetics for 5-nitroimidazoles (5-NDZs). Hence, a rapid and effective method was proposed for determination of 5-NDZs in milk by combining M-NOP-based magnetic solid-phase extraction with high-performance liquid chromatography. Main extraction conditions were investigated. Under optimal conditions, good linear response was achieved in a range of 2.4-100 ng mL^-1 with a lower detection limit of 0.8-1.0 ng mL^-1. High accuracy with a recovery of 80.0-116.0% for the fortified samples, good repeatability with relative standard deviation below 10%, and a high enrichment factor of 97-111 were obtained. The rapid adsorption of 5-NDZs on M-NOP is mainly driven by H-bonding, π-stacking, and polar interactions. Finally, the M-NOP-based method was successfully used to determine 5-NDZs in milk samples. The M-NOP is expected to present promising application in the extraction and quantitative analysis of other compounds.