In situ growth of covalent organic framework on titanium fiber for headspace solid-phase microextraction of 11 phthalate esters in vegetables

Covalent organic framework-based solid phase microextraction coupled with electrospray ionization mass spectrometry for the quantitative assessment of abnormal bile acids by triclosan exposure in mice

Bile acids, a representative diagnostic indicator of liver function, are used to visualize the extent of liver injury. Numerous studies have shown that triclosan (TCS) exposure leads to abnormal bile acid metabolism. As a result, there is a requirement to develop a fast and smart means to quantitatively monitor abnormal bile acids from exposure to triclosan in bio-sample. In this work, solid-phase microextraction (SPME) probes of sea urchin-like covalent organic frameworks (COF) were in situ synthesized on steel needles by using 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP) as two organic units and employed for extraction of bile acids. This TAPB-DMTP-COF-SPME possessed an excellent specified surface area (3351 m2 g-1) and a high regular porosity (∼3.6 nm), which was an ideal adsorbent to concentrate bile acids efficiently. The created probe, together with electrospray ionization mass spectrometry (ESI/MS), proved to be a fast and specific assay for the detection of bile acids in bio-samples. The proposed method had a low limitation of detection (0.03 μg L-1), good linearity (R2 ≥ 0.9931), wide linear range (0.10-1000.00 μg L-1) and excellent enrichment factor (63.60-252.00). Based on these excellent properties, it was successful application for the analyzing of bile acids in mice liver and feces, demonstrating the great potential of TAPB-DMTP-COF-SPME-ESI/MS in bile acids detection and liver injury diagnosis.

A Novel Gully-like Surface of Stainless-Steel Fiber Coated with COF-TPB-DMTP Nanoparticles for Solid-Phase Microextraction of Phthalic Acid Esters in Bottled Tea Beverages

A covalent organic framework TPB-DMTP was physically coated onto the gully-like surface of stainless-steel fiber. The fabricated TPB-DMTP-coated stainless-steel fiber was used to extract five phthalic acid esters (PAEs) prior to the GC-FID separation and determination in bottled tea beverages. The developed SPME-GC-FID method gave limits of detection (S/N = 3) from 0.04 µg·L-1 (DBP) to 0.44 µg·L-1 (BBP), with the enrichment factors from 268 (DEHP) to 2657 (DPP). The relative standard deviations (RSDs) of the built method for inter-day and fiber-to-fiber were 4.1-11.8% and 2.3-9.9%, respectively. The prepared TPB-DMTP-coated stainless-steel fibers could stand at least 180 cycles without a significant loss of extraction efficiency. The developed method was successfully applied for the determination of trace PAEs in different bottled tea beverages, with recoveries from 85.5% to 115%.

A covalent organic framework-coated steel substrate as a mass spectrometric ionization source for the effective enrichment and rapid detection of phthalates in beverages

A novel, rapid, and simple detection method is proposed to realize the simultaneous detection of seven phthalate esters (PAEs) within 1.5 min. A suitable covalent organic framework (COF) was coated on a stainless steel substrate (COFCS) to serve as both an enrichment element and a solid substrate for electrospray ionization mass spectrometry (ESI-MS). Twenty microliters of elution solvent was added dropwise to the COFCS enriched with analytes, and then high voltage electricity was applied and combined with ambient mass spectrometry (AMS) to realize the detection of PAEs. In order to investigate the reliability of the COFCS-ESI-MS method, dimethyl phthalate (DMP), diethyl phthalate (DEP), ethyl phthalate (2-methoxy) (DMEP), phthalate(2-ethoxy) ethyl ester (DEEP), dipentyl phthalate (DPP), dihexyl phthalate (DHXP), and butyl benzyl phthalate (BBP) were detected simultaneously. The proposed method showed good linearity in the range 0.1-80 μg/L with the determination coefficient (R2) > 0.9916. The limits of detection (LODs) and limits of quantification (LOQs) of the determination technology were in the ranges 0.03-0.40 μg/L and 0.1-2.0 μg/L, respectively. The results demonstrated that the simultaneous detection of the seven PAEs in beverages can be realized using the method, and the spiked recoveries were in the range 85.17-104.09% with the relative standard deviations (RSDs) < 8.32%. In addition, the COFCS has good reusability and batch-to-batch repeatability and can be re-used at least 5 times and still maintain good enrichment performance.

The Preparation of Robust Gully-like Surface of Stainless Steel Fiber-Bonded TFPA-TTA-COF with Nano Pores for Solid-Phase Microextraction of Phenolic Compounds in Water

In this paper, a novel robust TFPA-TTA-COF coating with nano pores was grafted to the gully-like surface of stainless steel fibers (GS-SSF). The GS-SSF were prepared using a two-step electrochemical etching method, and the covalent organic framework (COF) TFPA-TTA-COF coating was chemically bonded to the gully-like surface via in situ growth. The prepared metal fibers were applied as the headspace solid-phase microextraction (HS-SPME) fibers and combined with gas chromatography (GC) to develop a detection method for phenolic compounds (PCs) in water. The developed method gave the limits of detection (S/N = 3) from 0.07 µg·L-1 to 0.52 µg·L-1 with enrichment factors from 243 to 2405. The relative standard deviations for inter-day study (n = 5) and fiber-to-fiber were from 3.94% to 8.89% and 2.17% to 8.05%, respectively. The prepared fiber could stand at least 180 cycles without remarkable loss of extraction efficiency. The developed method was successfully employed for the determination of trace PCs in environmental water with recoveries from 84.76% to 124.84%.

Fluorine-functionalized covalent organic framework coated solid-phase microextraction probe coupled with electrospray ionization mass spectrometry for monitoring triclosan, triclocarban, and chlorophenols in mice

Triclosan (TCS), triclocarban (TCC), and chlorophenols (CPs) are broad-spectrum antibacterials widely used in dermatological and oral hygiene products, which could induce severe liver and intestine injuries. Hence, it is essential to establish a rapid and sensitive method to monitor TCS, TCC, and CPs in various organisms. In this work, fluorine-functionalized covalent organic framework (COF-F) was prepared by using 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tri-aniline and 2,3,5,6-tetrafluoroterephthalaldehyde as two building units and employed as a solid phase microextraction (SPME) probe for the extraction of TCS, TCC and CPs. The COF-F possessed excellent hydrophobicity, a large specific surface area (1354.3 m2 g-1) and high uniform porosity (3.2 nm), which facilitated high selectivity and adsorption properties towards TCS, TCC, and CPs. Therefore, the as-prepared COF-F-SPME in combination with electrospray ionization mass spectrometry has been developed to provide fast and ultrasensitive detection of TCS, TCC, and CPs in biological samples. The established method demonstrated satisfactory linear ranges (0.01-100.00 μg L-1) and low limits of detection (0.003-0.040 μg L-1) for TCS, TCC and CPs. The developed method could be successfully applied to detect TCS, TCC and CPs in the liver and kidney tissues of mice, demonstrating the potential for the detection of chlorinated aromatic pollutants in the biological samples.

Covalent-Organic Frameworks for Selective and Sensitive Detection of Antibiotics from Water

As the consumption of antibiotics rises, they have generated some negative impacts on organisms and the environment because they are often unable to be effectively degraded, and seeking effective detection methods is currently a challenge. Covalent-organic frameworks (COFs) are new types of crystalline porous crystals created based on the strong covalent interactions between blocked monomers, and COFs demonstrate great potential in the detection of antibiotics from aqueous solutions because of their large surface area, adjustable porosity, recyclability, and predictable structure. This review aims to present state-of-the-art insights into COFs (properties, classification, synthesis methods, and functionalization). The key mechanisms for the detection of antibiotics and the application performance of COFs in the detection of antibiotics from water are also discussed, followed by the challenges and opportunities for COFs in future research.

Covalent Organic Frameworks Meet Titanium Oxide

In order to expand the applicability of materials and improve their performance, the combined use of different materials has increasingly been explored. Among these materials, inorganic-organic hybrid materials often exhibit properties superior to those of single materials. Covalent organic frameworks (COFs) are famous crystalline porous materials constructed by organic building blocks linked by covalent bonds. In recent years, the combination of COFs with other materials has shown interesting properties in diverse fields, and the composite materials of COFs and TiO2 have been investigated more and more. These two outstanding materials are combined through covalent bonding, physical mixing, and other methods and exhibit excellent performance in various fields, including photocatalysis, electrocatalysis, sensors, separation, and energy storage and conversion. In this Review, the current preparation methods and applications of COF-TiO2 hybrid materials are introduced in detail, and their future development and possible problems are discussed and prospected, which is of great significance for related research. It is believed that these interesting hybrid materials will show greater application value as research progresses.

Electrospun nanofibers-based thin film microextraction for enrichment of phthalate esters in biodegradable plastics

In this work, a novel electrospun nanofiber (PAN/TpBD; 2,4,6-triformylphloroglucinol [Tp] and benzidine [BD]; polyacrylonitrile [PAN]) was fabricated via a facile electrospinning method and utilized as adsorbent in thin film microextraction (TFME) of phthalate esters (PAEs) (dimethyl phthalate, diethyl phthalate, diallyl phthalate, dibutyl phthalate, and dioctyl phthalate) in biodegradable plastics. The prepared PAN/TpBD combines the strong stability of nanofibers with increased exposure sites for covalent organic frameworks and enhanced interactions with the target, thus improving the enrichment effect on the target. The extraction efficiency of PAN/TpBD reached above 80%. Based on PAN/TpBD, a TFME-high-performance liquid chromatography method was established, and the experimental parameters were optimized. Under the optimal extraction conditions, the PAEs of this method varied linearly in the range of 10-10 000 µg/L with low detection limits (0.69-2.72 µg/L). The intra-day and inter-day relative standard deviation values of the PAEs were less than 8.04% and 8.73%, respectively. The adsorbent can achieve more than 80% recovery of the five targets after six times reuse. The developed method was successfully applied for the determination of trace PAEs in biodegradable plastics with recoveries ranging from 80.1% to 113.4% and relative standard deviations were less than 9.45%. The as-synthesized PAN/TpBD adsorbent exhibited great potential in PAE analysis.

Membrane-protected magnetic covalent organic framework for efficient extraction of estrogens in dairy products

The presence of estrogens residues in dairy products is a growing concern due to their potential health risk. Herein, in this study, we have developed a membrane-protected magnetic solid-phase extraction (MP-MSPE) method that utilized a magnetic adsorbent (Fe3O4@COF-LZU1) with in-situ growth for the efficient extraction of estrone (E1), 17β-estradiol (E2), and estriol (E3). When combined with HPLC-FLD, this method allows for the efficient detection of estrogens in dairy products. The stability of the MP-MSPE was improved by the presence of a dialysis membrane, which remained a high extraction efficiency (90 %) even after ten reuse cycles. The hydrogen bonding, π-π interactions and pore size effect contribute to the excellent adsorption of three estrogens onto Fe3O4@COF-LZU1. Under optimal conditions, the method exhibits a low detection limit (0.01-0.15 μg L-1), wide linear range (0.1-800 μg L-1), and favorable recoveries (77.3 %-109.4 %) at three concentration levels (10, 50 and 100 μg L-1). This proposed method is characterized by its simplicity, high efficiency and eco-friendliness, making it a promising approach for extracting estrogens from dairy products.

Recent advance on microextraction sampling technologies for bioanalysis

The contents of target substances in biological samples are usually at low concentration levels, and the matrix of biological samples is usually complex. Sample preparation is considered a very critical step in bioanalysis. At present, the utilization of microextraction sampling technology has gained considerable prevalence in the realm of biological analysis. The key developments in this field focus on the efficient microextraction media and the miniaturization and automation of adaptable sample preparation methods currently. In this review, the recent progress on the microextraction sampling technologies for bioanalysis has been introduced from point of view of the preparation of microextraction media and the microextraction sampling strategies. The advance on the microextraction media was reviewed in detail, mainly including the aptamer-functionalized materials, molecularly imprinted polymers, carbon-based materials, metal-organic frameworks, covalent organic frameworks, etc. The advance on the microextraction sampling technologies was summarized mainly based on in-vivo sampling, in-vitro sampling and microdialysis technologies. Moreover, the current challenges and perspective on the future trends of microextraction sampling technologies for bioanalysis were briefly discussed.

Point-of-Use SERS Approach for Efficient Determination and Removal of Phthalic Acid Esters Based on a Metal-Organic Framework-Coated Melamine Sponge

Phthalic acid esters (PAEs) are ubiquitous environmental contaminants, and their real-time monitoring and removal remain challenging. Herein, a point-of-use (POU) device integrating adsorption, surface-enhanced Raman spectroscopy (SERS), and removal strategy was developed and realized ultrafast on-site determination of PAEs and cleanup of them from water. A piece of flexible melamine sponge (MS) was coated with gold nanostars (AuNSs) and metal-organic frameworks (MOFs), thus obtaining SERS activity and adsorption capacity. Based on this multifunctional AuNSs@MOFs/MS composite, clear trends were observed between SERS signal intensity and concentration of di(2-ethylhexyl)phthalate (DEHP) and dibutyl phthalate (DBP). The method detection limits of DEHP and DBP were calculated to be 0.75 × 10-7 and 0.67 × 10-7 M in water, respectively, proving good sensitivity. Furthermore, this POU device exhibited satisfactory adsorption capacity (∼82.3 g/g for DBP and ∼90.0 g/g for DEHP), high adsorption efficiency (equilibrium in 100 s), and good regeneration capability (removal efficiency >70% after 5 cycles). The applicability of this device was verified by its good determination and removal performance in real environmental water matrices. The whole process could be completed within 5 min. This approach provides a new POU alternative for real-time monitoring and removal of PAEs in water.

Recent progress of covalent organic frameworks as attractive materials for solid-phase microextraction: A review

Solid-phase microextraction (SPME) is a green, environmentally friendly, and efficient technique for sample pre-treatment. Covalent organic frameworks (COFs), a class of porous materials formed by covalent bonds, have gained prominence owing to their remarkable attributes, including large specific surface area, tunable pore size, and robust thermal/chemical stability. These characteristics have made COFs highly appealing as potential coatings for SPME fiber over the past decades. In this review, various methods used to prepare SPME coatings based on COFs are presented. These methods encompass physical adhesion, sol-gel processes, in situ growth, and chemical cross-linking strategies. In addition, the applications of COF-based SPME coating fibers for the preconcentration of various targets in environmental, food, and biological samples are summarized. Moreover, not only their advantages but also the challenges they pose in practical applications are highlighted. By shedding light on these aspects, this review aims to contribute to the continued development and utilization of COF materials in the field of sample pretreatment.

Facile fabrication of carbon nanotube hollow microspheres as a fiber coating for ultrasensitive solid-phase microextraction of phthalic acid esters in tea beverages

The efficient extraction of phthalic acid esters (PAEs) is challenging due to their extremely low concentration, complicated matrices and hydrophilicity. Herein, hollow microspheres, as an ideal coating, possess significant potential for solid-phase microextraction (SPME) due to their fascinating properties. In this study, multiwalled carbon nanotube hollow microspheres (MWCNT-HMs) were utilized as a fiber coating for the SPME of PAEs from tea beverages. MWCNT-HMs were obtained by dissolving the polystyrene (PS) cores with organic solvents. Interestingly, MWCNT-HMs well maintain the morphology of the MWCNTs@PS precursors. The layer-by-layer (LBL) assembly of MWCNTs on PS microsphere templates was achieved through electrostatic interactions. Six PAEs, di-ethyl phthalate (DEP), di-iso-butyl phthalate (DIBP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DOP), were selected as target analytes for assessing the efficiency of the coating for SPME. The stirring rate, sample solution pH and extraction time were optimized by using the Box-Behnken design. Under optimal working conditions, the proposed MWCNT-HMs/SPME was coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) to achieve high enrichment factors (118-2137), wide linearity (0.0004-10 μg L-1), low limits of detection (0.00011-0.0026 μg L-1) and acceptable recovery (80.2-108.5%) for the detection of PAEs. Therefore, the MWCNT-HM coated fibers are promising alternatives in the SPME method for the sensitive detection of PAEs at trace levels in tea beverages.

Hierarchical covalent organic framework hollow nanofibers-bonded stainless steel fiber for efficient solid phase microextraction

The solid phase microextraction (SPME) technique has been widely applied in the detection of trace compounds in food, environment, and medicine due to its advantages of easy quantification, simple operation, and greenness. Herein, a templating strategy with SiO2 nanofibers (SiO2 NFs) is reported to synthesize hierarchical covalent organic framework hollow nanofibers (COF HNFs)-coated stainless steel fiber for SPME application with dramatically enhanced enrichment performance for trace analytes. The construction of hierarchical porosity inside the microextraction coatings can not only increase the specific surface area of COF extraction materials for obtaining more abundant adsorption sites but also greatly improve the accessibility of internal COF micropores. Moreover, the thicknesses of the microextraction COF coatings can be facilely tailored by adjusting the amount of SiO2 NFs pre-assembled on the SPME fibers. On the headspace solid phase microextraction (HS-SPME) of antimicrobial residues, the developed COF TpBD-Me2 HNFs-12 fibers achieve enrichment factors of 2026 and 1823 for thymol and carvacrol respectively, which are significantly higher than those obtained from the counterpart COF TpBD-Me2-bonded fiber (8.5-8.2 times) and commercial CAR/PDMS fiber (3.3-4.4 times). Furthermore, the developed method was demonstrated to have wide linearity (0.1-50 μg L-1), low limits of detection (0.010 μg L-1), good thermal stability and excellent reusability (>60 recycles), demonstrating great application potential in the extraction of trace organic pollutants. The strategy developed in this work is applicable to preparing a variety of topological COF (e.g., TpBD, TpPa-1) HNFs-bonded fibers.

Headspace Microextraction. A Comprehensive Review on Method Application to the Analysis of Real Samples (from 2018 till Present)

This work describes current trends in the development of headspace microextraction methods. The main trends in the selection of detection techniques used in combination with microextraction and preferences in the selection of headspace liquid-phase microextraction (HS-LPME) or headspace solid-phase microextraction (HS-SPME) methods, depending on the analytes and their quantity, are also briefly presented. In the main part of the work, on the basis of current journal literature, headspace microextraction analytical methods used for the determination of various inorganic and organic analytes are classified and compared over the last five years. The work also reflects the current modifications of techniques and approaches proposed for these microextraction methods.

Quinoline Bridging Hyperconjugated Covalent Organic Framework as Solid-Phase Microextraction Coating for Ultrasensitive Determination of Phthalate Esters in Water Samples

Phthalate esters (PAEs) are widely distributed in the environment, and this has caused serious health and safety concerns. Development of rapid and ultrasensitive identification and analysis methods for phthalate esters is urgent and highly desirable. In this work, a novel nitrogen-rich covalent organic framework (N-TTI) derived quinoline bridging covalent organic framework (N-QTTI) was fabricated and used as a solid-phase microextraction (SPME) coating for the ultrasensitive determination of phthalate esters in water samples. The physical and chemical properties of N-QTTI were investigated sufficiently. The N-QTTI-coated fiber demonstrates a superior enrichment performance than either the N-TTI-coated fiber or commercial fibers under the optimized SPME conditions. For the first time, we propose a semi-immersion strategy for the extraction of PAEs from water samples based on N-QTTI-coated SPME fibers. Combined with gas chromatography-mass spectrometry (GC-MS), the developed method N-QTTI-SPME-GC-MS exhibits a wide linear range with a satisfactory linearity (R2 ≥ 0.995). The limits of detection (LOD, S/N = 3) and the limits of quantification (LOQs, S/N = 10) were 0.17-1.70 and 0.57-5.60 ng L-1, respectively. The repeatability of the new method was examined using relative standard deviations (RSDs) between intraday and interday data, which were 0.38-7.98% and 1.22-6.60%, respectively. The spiked recoveries at three levels of 10, 100, and 1000 ng L-1 were in the range of 90.0-106.2% with RSDs of less than 7.48%. The enrichment factors ranged from 291 to 17180. When compared to previously published works, the LODs of the newly established method were improved 5-5400 times, and the enrichment factors were increased by at least 8 times. The absorption mechanism was investigated by X-ray photoelectron spectroscopy and noncovalent interaction force analysis. The technique was successfully employed for detecting PAEs in water samples.

Covalent organic framework-based magnetic solid-phase extraction coupled with gas chromatography-tandem mass spectrometry for the determination of trace phthalate esters in liquid foods

Covalent organic framework-coated magnetite particles (Fe3O4@COF) were synthesized and applied as the adsorbent to the selective capture of phthalate esters (PAEs) in liquid foods. Combined with the magnetic solid-phase extraction (MSPE) technology, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method was employed for the separation and quantification of PAEs. Following optimization of the magnetic extraction and elution parameters, the developed analytical method offered a satisfactory linear range (0.1-5 μg L-1) with determination coefficients ranging from 0.9934 to 0.9975 for the five different PAEs studied. The limits of detection (LOD) were in the range 1.9-12.8 ng L-1. The recoveries ranged from 70.0 to 119.8% with a relative standard deviation (RSD) less than 9.7%. Density functional theory (DFT) calculations established that the dominant adsorption mechanism used by the COF to bind PAEs involved π-π stacking interactions. Results encourage the wider use of COF-based adsorbents and MSPE methods in the analytical determination of PAEs in foods.

Influence of different concentrations of plasticizer diethyl phthalate (DEP) on toxicity of Lactuca sativa seeds, Artemia salina and Zebrafish

Like other phthalates, diethyl phthalate (DEP) is considered as a contaminant of emerging concern (CEC) due to its ease in migrating from a package to water and food, and hence contaminate consumers, being metabolized and excreted in the urine. Its presence has a negative impact on aquatic ecosystems, especially with respect to disruption of the endocrine system and to reproductive disorders in humans. It mainly enters water bodies via sewage effluents from effluent treatment plants, due to its incomplete or inefficient removal. The objective of this work was to evaluate the toxicity of DEP at different trophic levels and to analyze data on the incidence and concentration of DEP according to its solubility. The concentrations ranged from 12.5 mg L-1 to 500 mg L-1 considering the response for toxicity at each trophic level and to determine the lethal concentration in 50% of the following organisms (LC50) (in mg L-1): Lactuca sativa seeds, Artemia salina Leach nauplii and Zebrafish embryo larval stage (Danio rerio), being 41,057.58 after 120 h; 401.77 after 48 h; and 470 after 96 h of exposure, respectively. As expected, higher organisms were more affected even at low concentrations, which shows the anthropological contribution of CECs to water bodies.

A Review of the Analysis of Phthalates by Gas Chromatography in Aqueous and Food Matrices

As a commonly well-known industrial chemical, phthalates are produced in high volumes to be used in various consumer products (e.g., plasticizers, medical devices, construction materials, and toys) to enhance softness, durability, transparency, and flexibility. Phthalates are generally not chemically bonded to the polymer chain of the plastic in which they are mixed. Thus, they may leach, migrate, or evaporate into indoor/outdoor air, and foodstuffs. In this review, a comprehensive overview of several sample preparation methods coupled with gas chromatography for the analysis of phthalates in various kinds of complex matrices, with a focus on the last 20 years' worth of papers. The review begins by highlighting the environmental significance of phthalate pollution along with the various routes to their exposure to general population. Then, the discussion is extended to cover the pretreatment and extraction techniques for phthalates for their quantitation based on gas chromatographic approach. Finally, the present and future challenges for the detection of phthalates in aqueous and food matrices are discussed.

A robust and ultra-high-surface hydrogen-bonded organic framework promoting high-efficiency solid phase microextraction of multiple persistent organic pollutants from beverage and tea

Persistent organic pollutants (POPs) are widely distributed in the environment and are toxic, even at low concentrations. In this study, we first used hydrogen-bonded organic framework (HOF) to enrich POPs, based on solid phase microextraction (SPME). The HOF called PFC-1 (self-assembled by 1,3,6,8-tetra(4-carboxylphenyl)pyrene) has an ultra-high specific surface area, excellent thermochemical stability, and abundant functional groups, making it potential to be an excellent coating in SPME. And the as-prepared PFC-1 fiber have demonstrated outstanding enrichment abilities for nitroaromatic compounds (NACs) and POPs. Furthermore, the PFC-1 fiber was coupled with gas chromatography-mass spectrometry (GC-MS) to develop an ultrasensitive and practical analytical method with wide linearity (0.2-200 ng·L^-1), low detection limits for organochlorine pesticides (OCPs) (0.070-0.082 ng·L^-1) and polychlorinated biphenyls (PCBs) (0.030-0.084 ng·L^-1), good repeatability (6.7-9.9%), and satisfactory reproducibility (4.1-8.2%). Trace concentrations of OCPs and PCBs in drinking water, tea beverage, and tea were also determined precisely with the proposed analytical method.

A novel porphyrin-based conjugated microporous nanomaterial for solid-phase microextraction of phthalate esters residues in children's food

A novel porphyrin-based conjugated microporous polymer (PCMP) with microporous structure and nitrogen-rich pyrrole building blocks was synthesized. The PCMP was used as a coating material to prepare solid-phase microextraction (SPME) fibers by sol-gel technique. Due to the toxicity of the phthalate esters (PAEs) and the necessity for their sensitive determinations in some food samples, the SPME fiber was investigated for the extraction of eleven PAEs from six different children's milk beverages prior to their detection by gas chromatography-mass spectrometry. Under the optimal conditions, the linear response range for the PAEs was in the range from 0.03 to 200 µg L^-1 and the limits of detection (S/N = 3) for the analytes were 0.01-3.00 μg L^-1. The method recoveries for the PAEs were between 80% and 120%, with the relative standard deviations varying from 1.3% to 9.8%. The method was successfully applied for the determination of PAEs in children's milk beverages.

[Application progress of covalent organic framework materials in extraction of toxic and harmful substances]

Toxic and hazardous substances constitute a category of compounds that are potentially hazardous to humans, other organisms, and the environment. These substances include pesticides (benzoylureas, pyrethroids, neonicotinoids), persistent organic pollutants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, perfluorinated compounds), plasticizers (phthalate esters, phenolic endocrine disruptors), medicines (sulfonamides, non-steroid anti-inflammatory drugs, tetracyclines, fluoroquinone antibiotics), heterocyclic aromatic amines, algal toxins, and radioactive substances. Discharge of these toxic and harmful substances, as well as their possible persistence and bioaccumulation, pose a major risk to human health, often to the extent of being life-threatening. Therefore, it is important to analyze and detect toxic and hazardous substances in the environment, drinking water, food, and daily commodities. Sample pretreatment is an imperative step in most of the currently used analytical methods, especially in the analysis of trace toxic and harmful substances in complex samples. An efficient and fast sample pretreatment technology not only helps improve the sensitivity, selectivity, reproducibility, and accuracy of analytical methods, but also avoids contamination of the analytical instruments and even damages the performance and working life of instruments. Sample pretreatment techniques widely used in the extraction of toxic and hazardous substances include solid-phase extraction (SPE), solid-phase microextraction (SPME), and dispersed solid-phase extraction (DSPE). The adsorbent material plays a key role in these pretreatment techniques, thereby determining their selectivity and efficiency. In recent years, covalent organic frameworks (COFs) have attracted increasing attention in sample pretreatment. COFs represent an exciting new class of porous crystalline materials constructed via the strong covalent bonding of organic building units through a reversible condensation reaction. COFs present four advantages: (1) precise control over structure type and pore size by consideration of the target molecular structure based on the connectivity and shape of the building units; (2) post-synthetic modification for chemical optimization of the pore interior toward optimized interaction with the target; (3) straightforward scalable synthesis; (4) feasible formation of composites with magnetic nanoparticles, carbon nanotubes, graphene, silica, etc., which is beneficial to enhance the performance of COFs and meet the requirement of diverse pretreatment technologies. Because of the well-defined crystalline porous structures and tailored functionalities, COFs have excellent potential for use in target extraction. However, some issues need to be addressed for the application of COFs in the extraction of toxic and hazardous substances. (1) For the sample matrix, most of the reported COFs are highly hydrophobic, which limits their dispersibility in water-based samples, leading to poor extraction performance. COFs with good dispersibility in water-based samples are urgently required. (2) Besides, COFs rely on hydrophobic interaction, size repulsion, π-π stacking, and Van der Waals forces to extract target substances, but they are not effective for some polar targets. Thus, it is necessary to develop COFs with high affinity for polar toxic and hazardous substances. (3) Methods for the synthesis of COFs have evolved from solvothermal methods to room-temperature methods, mechanical grinding, microwave-assisted synthesis, ion thermal methods, etc. Most of the existing methods are time-consuming, laborious, and environmentally unfriendly. The starting materials are too expensive to prepare COFs in large quantities. More effort is required to improve the synthesis efficiency and overcome the obstacles in the application of COFs for extraction. This article summarizes and reviews the research progress in COFs toward the extraction of toxic and hazardous substances in recent years. Finally, the application prospects of COFs in this field are summarized, which serves as a reference for further research into pretreatment technologies based on COFs.

Fabrication of magnetic covalent organic framework for efficient extraction and determination of phthalate esters in milk samples

Using two monomers of 4,4″-diamino-p-terphenyl and 1,3,5-triformylphloroglucinol, a co-precipitation structured magnetic covalent organic framework adsorbent was fabricated. After that, a high efficient vortex-assisted magnetic solid-phase extraction method was developed prior to gas chromatography-tandem mass spectrometry analysis for the determination of phthalate esters in milk samples. The fabricated magnetic adsorbent was facilely fabricated, fully characterized, and exhibited high extraction efficiency, which can be attributed to its larger pore size as well as strong hydrophobic and π-π stacking interactions between adsorbent and phthalate esters. Key parameters affecting extraction efficiency were investigated. Under the optimized conditions, the proposed method possessed good linearity (3.0-1000 μg/L), high sensitivity (0.8-2.1 μg/L for limits of detection), and satisfactory recoveries (76.8%-99.2%). The relative standard deviations for intra-day was 3.1%-4.5% and inter-day was 3.3%-6.1%. This work is suitable for high efficient separation/preconcentration of phthalate esters in milk samples.

Polyoxometalate-based materials in extraction, and electrochemical and optical detection methods: A review

Polyoxometalates (POMs) as metal-oxide anions have exceptional properties like high negative charges, remarkable redox abilities, unique ligand properties and availability of organic grafting. Moreover, the amenability of POMs to modification with different materials makes them suitable as precursors to further obtain new composites. Due to their unique attributes, POMs and their composites have been utilized as adsorbents, electrodes and catalysts in extraction, and electrochemical and optical detection methods, respectively. A survey of the recent progress and developments of POM-based materials in these methods is therefore desirable, and should be of great interest. In this review article, POM-based materials, their properties as well as their identification methods, and analytical applications as adsorbents, electrodes and catalysts, and corresponding mechanisms of action, where relevant, are reviewed. Some current issues of the utilization of these materials and their future prospects in analytical chemistry are discussed.

The electrospun polyacrylonitrile/covalent organic framework nanofibers for efficient enrichment of trace sulfonamides residues in food samples

In this work, the electrospun polyacrylonitrile/covalent organic frameworks Tp-BD nanofibers (PAN/Tp-BD) were synthesized and applied as an adsorbent for thin film microextraction (TFME) of seven sulfonamides in animal derived food samples. The morphology, structure, porosity, and stability of the prepared nanofibers were investigated. The PAN/Tp-BD nanofibers exhibited good chemical stability, high flexibility, porous fibrous structure, and excellent extraction efficiency. Based on the PAN/Tp-BD nanofibers as the adsorbent, a thin film microextraction-high performance liquid chromatography (TFME-HPLC) method for the determination of seven sulfonamides (SAs) in food samples was developed. Under the optimal conditions, the TFME-HPLC exhibited the low limit of detection (0.10-0.18 ng·mL^-1), the low limit of quantitation (0.33-0.60 ng·mL^-1), the wide linear range (0.5-50 ng·mL^-1) with correlation coefficients between 0.994 and 0.998, and good enrichment factors between 39.7 to 170.1 towards 20 ng/mL SAs solution. The relative standard deviation (RSD) was lower than 11% in the interday and intraday analysis. Furthermore, the applicability of PAN/Tp-BD nanofibers was demonstrated for measuring trace SAs residues in the spiked food samples with recoveries ranging from 85.3% to 115.2%. The results demonstrated that the PAN/Tp-BD nanofibers have great potential for the efficient extraction of sulfonamides from complex food samples.

Self-assembly of core-shell structured multiwalled nanotubes@covalent organic frameworks composite for solid-phase extraction of four phytohormones from fruit juices

Covalent organic frameworks (COFs) have attracted considerable attention in sample pretreatment because of their unique characteristics. However, the submicron or micron size of COFs has restricted their wider applications in solid-phase extraction (SPE). Herein, multiwalled nanotubes (MWNTs) were used as substrate materials to synthesize core-shell structured MWNTs@COFs composites (MWNTs@SNW-1) using a simple self-assembly method. The as-prepared MWNTs@SNW-1 composite exhibited a high BET surface area, good thermal stability, and good adsorption capacity. The MWNTs@SNW-1 composite was used as an adsorbent in cartridge-based SPE to extract four phytohormones before determining their levels by high-performance liquid chromatography. The experimental parameters affecting extraction efficiency, including the amount of adsorbents, solution pH, ionic strength, eluent type, and eluent volume, were investigated. The developed method showed a wide linear range (0.37-100 ng mL^-1), low detection limits (0.11-0.32 ng mL^-1), low limits of quantification (0.37-1.07 ng mL^-1), high enrichment factors (45.9-49.3), and good reproducibility (<4.8%) for phytohormones. The developed analytical method was used to analyze trace phytohormones in fruit juices with good recoveries, highlighting the potential of the MWNTs@SNW-1 composite as an adsorbent in sample preparation.

Comprehensive Strategy for Sample Preparation for the Analysis of Food Contaminants and Residues by GC-MS/MS: A Review of Recent Research Trends

Food safety and quality have been gaining increasing attention in recent years. Gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), a highly sensitive technique, is gradually being preferred to GC-MS in food safety laboratories since it provides a greater degree of separation on contaminants. In the analysis of food contaminants, sample preparation steps are crucial. The extraction of multiple target analytes simultaneously has become a new trend. Thus, multi-residue analytical methods, such as QuEChERs and adsorption extraction, are fast, simple, cheap, effective, robust, and safe. The number of microorganic contaminants has been increasing worldwide in recent years and are considered contaminants of emerging concern. High separation in MS/MS might be, in certain cases, favored to sample preparation selectivity. The ideal sample extraction procedure and purification method should take into account the contaminants of interest. Moreover, these methods should cooperate with high-resolution MS, and other sensitive full scan MSs that can produce a more comprehensive detection of contaminants in foods. In this review, we discuss the most recent trends in preparation methods for highly effective detection and analysis of food contaminants, which can be considered tools in the control of food quality and safety.

In situ room-temperature rapidly fabricated imine-linked covalent organic framework coated fibers for efficient solid-phase microextraction of pyrethroids

A facile and rapid strategy for preparation of covalent organic framework (COF) coated fibers at ambient temperature is urgently needed for solid-phase microextraction (SPME) technology. In this work, an in situ room-temperature rapid growth strategy was developed to high-efficiently fabricate imine-linked COF (TPB-DVA) coated fibers in as little as 30 min at room temperature, and the thickness of the coating reached 9 μm. The prepared TPB-DVA coated fiber offer high thermal and chemical stability, and outstanding service lifetime. Moreover, we generalize this strategy to other two imine-linked COF (TPB-DMTP and TFPB-TAPB) coated fibers and the fibers were fabricated at room temperature for 3 h and 12 h, respectively, which demonstrate the applicability of this strategy. Subsequently, a SPME-GC-MS/MS analytical method was developed for trace pyrethroids (PYs) detection, which exhibited high enhancement factors (EFs, 2700-13195), wide linear range (0.08-800 ng L^-1), low limits of detection (LODs, 0.02-0.20 ng L^-1), and good repeatability (RSD ≤ 8.5%, n = 6). Furthermore, the developed analytical method was applied to tea samples and trace PYs (1.31-4.32 ng L^-1) were found with satisfactory recovery (80.2-119.8%). The above results demonstrated that the feasibility of the developed strategy for the facile and rapid fabrication of imine-linked COF coated fibers.

A solid-phase microextraction fiber coating based on magnetic covalent organic framework for highly efficient extraction of triclosan and methyltriclosan in environmental water and human urine samples

Herein, we synthesized a kind of magnetic covalent organic framework nanohybrids (NiFe₂O₄@COF), and integrated it with polydimethyl siloxane and silicone rubber curing agent for solid phase microextraction (SPME) fiber coating. The fiber coating demonstrated a porous and uniform surface with the BET specific surface of 169.7 m² g^-1. As for seven environmental analytes, the NiFe₂O₄@COF-based SPME fiber coating gave the higher extraction recoveries for triclosan (TCS) and methyltriclosn (MTCS) than those of fenpropathrin, bifenthrin, permethrin, fenvalerate and deltamethrin. Several operational parameters were rigorously optimized, such as extraction temperature, extraction time, thermal desorption time, solution pH and salt effect. Combined with the GC-ECD detection, the newly developed microextraction method supplied the wide linear range of 0.1-1000 µg L^-1 with the correlation coefficients of > 0.9995. The limits of detection (LODs) and limits of quantitation (LOQs) reached as low as 1-7 ng L^-1 and 3.3-23 ng L^-1, respectively. The intra-day and inter-day precisions in six replicates (n = 6 ) were < 3.55% and < 5.06%, respectively, and the fiber-to-fiber reproducibility (n = 3) was < 7.64%. To evaluate its feasibility in real samples, the fortified recoveries for TCS and MTCS, at low (0.2 µg L^-1), middle (2.0 µg L^-1) and high (20.0 µg L^-1) levels, varied between 81.9% and 119.1% in tap, river and barreled waters as well as male, female and children urine samples. Especially, it is worth mentioning that the NiFe₂O₄@COF-based SPME coating fiber can be recycled for at least 150 times with nearly unchanged extraction efficiency. Moreover, the extraction recoveries by the as-fabricated fiber coating were much higher than those by three commercial fibers (PDMS, PDMS/DVB and PDMS/DVB/CAR). Overall, the NiFe₂O₄@COF-based SPME is a convenient, sensitive, efficient and "green" pretreatment method, thereby possessing important application prospects in trace monitoring of TCS-like pollutants in complex liquid matrices.

Rapid recognition of di-n-butyl phthalate in food samples with a near infrared fluorescence imprinted sensor based on zeolite imidazolate framework-67

Di-n-butyl phthalate (DBP) as a plasticizer is widely used in food and chemical industries. It is harm to human health when it appeared in food and water. A novel near-infrared (NIR) fluorescence molecularly imprinted sensor based on CdTe quantum dots and zeolite imidazolate framework-67 was developed with a sol-gel polymerization method for rapid and sensitive determination of DBP in foodstuff rapidly (only in 1.5 min). The fluorescence imprinted sensor provided a rapid detection method for DBP in the linear response concentration range of 0.05-18.0 μM with a low detection limit of 1.6 nM. Compared with previous fluorescence imprinted sensor, it behaved faster response speed and lower detection limit for determination of DBP. The fluorescence imprinted sensor was used to detect DBP in real samples successfully with satisfied recoveries of 97.2-106.4%, suggesting a potential application in food analysis.

Sheathed in-situ room-temperature growth covalent organic framework solid-phase microextraction fiber for detecting ultratrace polybrominated diphenyl ethers from environmental samples

The extraction performance of solid-phase microextraction (SPME) fiber is significantly influenced by coating materials and fabricating process. It is urgently needed for fabricating robust SPME fiber with facile preparation methods. Herein, a novel polyimide (PI) @ covalent organic framework (COF) synthesized by 1,3,5-Tris (4-aminophenyl) benzene (TPB) and 2,5-dimethoxyterephthalaldehyde (DMTP) fiber, named PI@TPB-DMTP fiber, was successfully fabricated with facile method at room temperature. Firstly, a COF crystals TPB-DMTP was in situ grown on stainless steel fiber, where the COF crystals was synthesized by the Schiff-base reaction between TPB and DMTP. Subsequently, the COF coating was covered with an ultrathin layer of PI through a simple dip-coating method to improve the fiber stability. By coupled PI@TPB-DMTP SPME fiber with gas chromatography-negative chemical ion-mass spectrometry (GC-NCI-MS), a sensitive analytical method was established for the determination of ultratrace polybrominated diphenyl ethers (PBDEs) in water sample. To achieve the best efficiency and sensitivity for the analysis of PBDEs, six potential influencing factors in extraction step and desorption step were optimized. Under optimized conditions, the established method showed high enhancement factors of 1470-3555, wide linear range of 0.05-100 ng L^-1, low detection limits of 0.0083-0.0190 ng L^-1, good repeatability for intra-day in the range of 3.71%-7.62% and inter-day in the range of 5.12%-8.81%, good reproducibility in the range of 6.83%-9.21%. The satisfactory recovery was ranged from 79.2% to 117.3% in determining real water samples. The excellent experimental performance was mainly attributed to the large specific surface area of TPB-DMTP, as well as the high permeability of porous PI film. The results demonstrated that the COF-based fiber showed great potential for analysis of PBDEs in complex environmental samples.

[Preparation of covalent organic framework based on room temperature solution-suspension approach and its application to solid-phase microextraction of pyrethroids in tea]

Pyrethroids (PYs) have been widely used to control pests and prevent diseases in tea gardens. However, with the increasingly stringent pesticide testing standards in the import and export trade of tea, there is an urgent need for methods to detect trace amounts of PYs in tea. In this study, a covalent organic framework (COF) material TpBD with excellent thermal/chemical stability, high porosity, and a large specific surface area was prepared by a room-temperature solution-suspension approach (SSA). TpBD-coated solid phase microextraction (SPME) fibers were fabricated by coating the material on etched stainless-steel fibers by a simple physical coating method. The fibers were used in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS) to establish a highly sensitive method for the detection of PYs. The enrichment factors of this method for cyfluthrin, cypermethrin, flucythrinate, fenvalerate, and deltamethrin were 702-2687. The method showed low LODs (0.1-0.5 ng/L), wide linear ranges (0.2-800 ng/L), good linearities (correlation coefficients (R)≥0.9991) and acceptable repeatabilities (RSD≤11.0%, n=3). Green tea and oolong tea samples were analyzed using the developed method, and trace levels of the five PYs were successfully detected. The recoveries of the spiked PYs in the real green tea and oolong tea samples were in the range of 80.2%-109.5%. Experimental results showed that the established analytical method is suitable for the determination of PY pesticides in tea. Furthermore, the TpBD material was successfully prepared by the SSA method, demonstrating that the method has good universality and excellent potential for the simple synthesis of other COF materials.

Evaluation of the Occurrence of Phthalates in Plastic Materials Used in Food Packaging

Phthalates are multifunctional synthetic chemicals found in a wide array of consumer and industrial products, mainly used to improve the mechanical properties of plastics, giving them flexibility and softness. In the European Union, phthalates are prohibited at levels greater than 0.1% by weight in most food packaging. In the current study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was optimized, through the multivariate optimization process, and validated to evaluate the occurrence of four common phthalates, di-iso-butyl phthalate (DIBP), butyl-benzyl phthalate (BBP), di-n-octyl phthalate (DOP), and 2,2,4,4-tetrabromodiphenyl (BDE), in different food packaging. The best extraction efficiency was achieved using the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber at 80 °C for 30 min. The validated method showed good linearity, precision (RSD < 13%), and recoveries (90.2 to 111%). The limit of detection (LOD) and of quantification (LOQ) ranged from 0.03 to 0.08 µg/L and from 0.10 to 0.24 µg/L, respectively. On average, the phthalates concentration varied largely among the assayed food packaging. DIBP was the most predominant phthalate in terms of occurrence (71.4% of analyzed simples) and concentration (from 3.61 to 10.7 μg/L). BBP was quantified in only one sample and BDE was detected in trace amounts (<LOQ) in only two samples.

Construction of hypercrosslinked polymers for high-performance solid phase microextraction of phthalate esters from water samples

Design and synthesis of novel coatings for solid phase microextraction (SPME) is urgently needed for sample pretreatment. In this study, three hypercrosslinked polymers (HCPs) were constructed by the facile Friedel-Crafts alkylation reactions between tetraphenylethylene (TPE) and 1,4-bis(chloromethyl)benzene (BCMB), 4,4'-bis(chloromethyl)-1,1'-biphenyl (BCMBP), and cyanuric chloride (CC), respectively. The newly-synthesized HCPs were employed as SPME coatings for the extraction of phthalate esters (PAEs). Various parameters influencing the SPME efficiencies, including extraction time and temperature, ionic strength, stirring rate, desorption temperature and time were optimized. Under the optimal conditions, low limits of detection (0.003-0.033 μg L ^- 1), wide linearity (0.01-10 μg L ^- 1) and good repeatability (4.1-9.3%) were achieved. The HCPs-based SPME method was successfully applied for the determination of eight PAEs in environmental water and bottled water samples with recoveries from 75.3% to 116%. This method provides a good alternative for monitoring trace level of PAEs in water samples.

Electro-enhanced solid-phase microextraction with covalent organic framework modified stainless steel fiber for efficient adsorption of bisphenol A

In this work, electro-enhanced solid-phase microextraction (EE-SPME) and covalent organic framework (COF) were adopted to improve the extraction efficiency. A conductive COF synthesized of 2,6-diaminoanthraquinone (DQ) and 1,3,5-triformylphloroglucinol (TP) was in situ bonded to the stainless steel wire via facile solution-phase approach and used as the EE-SPME fiber coating to preconcentrate a typical endocrine disruptor bisphenol A (BPA). Compared with conventional SPME, the DQTP bonded fiber coupled with EE-SPME device exhibited higher extraction efficiency and achieved extraction equilibrium within 10 min. The proposed approach based on EE-SPME and gas chromatography coupled with flame ionization detector gave a linear range of 0.05-10 μg mL^-1 and detection limit of 3 μg L^-1 (S/N = 3) with good precision (<6.7%) and reproducibility (<7.1%) spiked with 0.1, 0.5, 1.0 μg mL^-1 BPA. Quantitative determination of BPA in extracts of food packagings (mineral water bottles, milk boxes and milk tea cups) was achieved with recoveries from 88.6 to 118.0%.

Applications of porous frameworks in solid-phase microextraction

Porous frameworks are a term of attracting solid materials assembled by interconnection of molecules and ions. These trendy materials due to high chemical and thermal stability, well-defined pore size and structure, and high effective surface area gained attention to employ as extraction phase in sample pretreatment methods before analytical analysis. Solid-phase microextraction is an important subclass of sample preparation technique that up to now different configurations of this method have been introduced to get adaptable with different environments and analytical instruments. In this review, theoretical aspect and different modes of solid-phase microextraction method are investigated. Different classes of porous frameworks and their applications as extraction phase in the proposed microextraction method are evaluated. Types and features of supporting substrates and coating procedures of porous frameworks on them are reviewed. At the end, the prospective and the challenges ahead in this field are discussed.

Covalent Organic Framework Composites: Synthesis and Analytical Applications

In the recent years, composite materials containing covalent organic frameworks (COFs) have raised increasing interest for analytical applications. To date, various synthesis techniques have emerged that allow for the preparation of crystalline and porous COF composites with various materials. Herein, we summarize the most common methods used to gain access to crystalline COF composites with magnetic nanoparticles, other oxide materials, graphene and graphene oxide, and metal nanoparticles. Additionally, some examples of stainless steel, polymer, and metal-organic framework composites are presented. Thereafter, we discuss the use of these composites for chromatographic separation, environmental remediation, and sensing.

Nano-optosensor based on titanium dioxide and graphene quantum dots composited with specific polymer for cefazolin detection

An optosensor using nanocomposite probes was fabricated for the detection of trace cefazolin. The nanoprobes utilized the high affinity of titanium dioxide, the good optical properties of graphene quantum dots and the good selectivity of molecularly imprinted polymer. The integration of these materials produced a rapid, highly sensitive optosensor with excellent selectivity for cefazolin detection. The fluorescence intensity of the nanocomposite probes was quenched when cefazolin re-bound with the imprinted recognition cavities of the nanoprobes. The fabricated nanoprobe exhibited a good linearity for cefazolin from 0.10 to 10.0 μg L^-1 with a limit of detection of 0.10 μg L^-1. The imprinting factor of the nanoprobe was 10.6 and selectivity for cefazolin was not affected by the analogue structures of cephalexin, cefatriaxone, cephradine, cefaperazone and ceftazidime. This nano-optosensor probe successfully detected cefazolin in milk and recoveries were between 85.0 and 97.4 % with RSDs less than 5.0 %. The results of analysis with nano-optosensor were in good agreement with HPLC analysis. The fabrication strategy of the nanocomposite probe can be modified for the measurement of other toxic compounds.

In-situ layer-by-layer synthesized TpPa-1 COF solid-phase microextraction fiber for detecting sex hormones in serum

The secretion disorder of sex hormones is the source that leads to the occurrence of many diseases such as polycystic ovarian syndrome (PCOS), hyperandrogenism and so on. There exist physiological changes in human body when slight fluctuations in concentrations of sex hormones happen. Therefore, it's of great significance for accurate detection of sex hormones in human body. In this work, TpPa-1 COF solid-phase microextraction (SPME) fiber was prepared using high-efficient in-situ synthesis strategy and coupled with HPLC-MS/MS to detect three sex hormones, including Progesterone (P), testosterone (T) and dehydroepiandrosterone (DHEA) in human serum. The thickness of the coating reached 7 μm within 2 h. Under the optimal conditions, the established method presented low limit of detections (LODs, ≤ 0.75 ng/mL), wide linear ranges (0.100-100 ng mL^-1) and good reproducibility, and three sex hormones (T, P, DHEA) were successfully detected and quantified in human serum. In conclusion, the established SPME method presented high-efficient fiber preparation and good analytical performances of sex hormone detection, therefore was in great potential for application in clinical.