Quinolyl functionalized three-dimensional covalent organic framework material, solid-phase microextraction probe and application

Abstract

The invention discloses a quinolyl-functionalized three-dimensional covalent organic framework material, a solid-phase microextraction probe and application, the quinolyl-functionalized three-dimensional covalent organic framework material is formed by modifying 3D-COF with sodium p-styrenesulfonate, and the material is marked as 3D-QS-COF; the 3D-COF is formed by copolymerizing benzidine and 4 ', 5'-bis (3, 5-dimethylphenyl)-3 ', 6'-dimethyl-[1, 1 ': 2', 1 ''-triphenyl] 3, 3 '', 5, 5 ''-tetracarboxaldehyde. According to the preparation method, sodium p-styrenesulfonate is used for post-modification, 3D-QS-COF is synthesized through a Povarov reaction, functional sites and pore structures are regulated and controlled, and pore channel collapse and crystallinity disappearance are avoided; the polychlorinated biphenyl derivative has a large number of quinoline rings, benzene rings and sodium sulfonate groups, so that the polychlorinated biphenyl derivative has more binding sites and can interact with various polychlorinated biphenyl, and a foundation is laid for high-precision detection of trace or ultra-trace polychlorinated biphenyl in food.

Description

Technical Field

[0001] This invention relates to the field of analytical technology, and in particular to a quinoline-functionalized three-dimensional covalent organic framework material, a solid-phase microextraction probe, and its applications. Background Technology

[0002] Polychlorinated biphenyls (PCBs) are persistent organic pollutants that affect the human immune, reproductive, nervous, and endocrine systems, posing a serious threat to human health. Even at trace levels, they can cause significant environmental and biological damage due to their bioaccumulation and persistence. The main sources of PCB emissions are the combustion of household waste, medical waste, landfills, and fires. These sources cause PCBs to evaporate into the air, then accumulate in plants and soil, contaminating crops and animal feed, and ultimately ending up in the human body through the food chain. PCBs are carcinogenic to humans, and excessive exposure can lead to impaired immune function, hearing loss, and neurological disorders. Therefore, PCB testing in food is essential.

[0003] For trace, ultra-trace (or even ultra-trace) analytes in complex matrices, sample purification is usually required before quantitative detection. Traditional sample pretreatment methods include liquid-liquid extraction, solid-phase extraction, liquid-liquid microextraction, magnetic solid-phase extraction, and dispersive solid-phase microextraction. However, these methods typically suffer from drawbacks such as cumbersome procedures, time-consuming steps, low selectivity, significant matrix effects, and high organic solvent consumption. Therefore, they often fail to meet the requirements for analyzing trace PCBs in complex matrices. In recent years, solid-phase microextraction (SPME), a promising sample pretreatment technique integrating sampling, concentration, and extraction, has attracted considerable attention due to its unique advantages such as simplicity, speed, cost-effectiveness, and low organic solvent consumption. For SPME, the extraction efficiency of the target analyte largely depends on the choice of fiber coating.

[0004] In recent years, many novel and highly efficient adsorbent materials, such as nanomaterials, graphene, covalent organic frameworks (COFs), and metal-organic frameworks (MOFs), have been applied in SPME coatings. Covalent organic frameworks (COFs) are porous crystalline organic materials composed of light elements such as C, H, O, N, and Si linked by strong covalent bonds, and are high-performance SPME adsorbents. Depending on their dimensionality, COFs are mainly classified as two-dimensional (2D) and three-dimensional (3D). 3D COFs, compared to 2D COFs, possess advantages such as diverse topological structures, multiple open sites, interpenetrating pore structures, and good stability, making them suitable as SPME coatings for the efficient enrichment of trace organic pollutants in complex matrices. However, the synthesis of 3D COFs, driven primarily by covalent bonds, faces challenges in maintaining crystallinity and stability during the synthesis process, and there are no reports on the use of 3D COFs for extracting trace or ultra-trace PCBs from food. Summary of the Invention

[0005] In view of this, the present invention proposes a quinoline-functionalized three-dimensional covalent organic framework material, a solid-phase microextraction probe, and its application in the detection of PCBs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The quinolinyl-functionalized three-dimensional covalent organic framework material of this invention is prepared by modifying 3D-COF with sodium p-styrene sulfonate, and is designated as 3D-QS-COF. 3D-COF is formed by copolymerizing benzidine and 4',5'-bis(3,5-dimethylphenyl)-3',6'-dimethyl-[1,1':2',1″-triphenyl]3,3″,5,5″-tetracarboxylic aldehyde. The structural formulas of 3D-COF and 3D-QS-COF are as follows: , .

[0007] The beneficial effects are as follows: This invention first synthesizes a three-dimensional organic framework material, and then uses sodium p-styrene sulfonate as a post-modification monomer to synthesize a quinoline-linked three-dimensional covalent organic framework material, 3D-QS-COF, via the Povarov reaction. This strategy effectively regulates the functional sites and pore structure of the material while stabilizing the structure and crystallinity of 3D COFs, preventing pore collapse and loss of crystallinity. Furthermore, the 3D-QS-COF of this invention possesses a large number of quinoline rings, benzene rings, and sodium sulfonate groups, giving it numerous binding sites. These sites allow it to interact with various polychlorinated biphenyls (PCBs) through CH…N, NH…Cl, π…π, CH…O, Lp…π, OH…Cl, and other interactions, laying the foundation for high-precision detection of trace or ultra-trace PCBs in food.

[0008] Preferably, the post-modification of 3D-COF with sodium p-styrene sulfonate includes the following: 2,3-dichloro-5,6-dicyanobenzoquinone, boron trifluoride ether, and toluene are added to 3D-COF and sodium p-styrene sulfonate in a reaction tube. After degassing by freezing-thawing cycle, the tube is sealed and reacted at a high temperature of 100℃~140℃ for 48 h~96 h. After the reaction, the tube is washed sequentially with THF, DMF, and ethanol (e.g., by vacuum filtration), followed by THF Soxhlet washing, and then dried (preferably vacuum dried overnight at 80℃) to obtain 3D-QS-COF.

[0009] Preferably, in the synthesis of 3D-COF, the molar ratio of 4',5'-bis(3,5-dimethylphenyl)-3',6'-dimethyl-[1,1':2',1″-triphenyl]3,3″,5,5″-tetracarboxaldehyde and benzidine is 1:4, and the reaction conditions are 100℃~140℃ for 48 h~96 h. This invention uses a solvothermal method to synthesize 3D-COF, which is simple and convenient.

[0010] This invention also proposes a solid-phase microextraction probe, comprising a needle body and a coating applied to the needle body. The coating utilizes the quinoline-functionalized three-dimensional covalent organic framework material 3D-QS-COF described in this invention. Experiments show that, compared to commercial probes, the probe PCBs of this invention exhibit stronger extraction capabilities. Furthermore, after 70 repeated uses, the extraction efficiency of the probe of this invention did not change significantly, further confirming its good stability and demonstrating its practical application prospects and commercial development value.

[0011] This invention also proposes the application of a solid-phase microextraction probe (coated with 3D-QS-COF) in the quantitative detection of trace or ultra-trace polychlorinated biphenyls (PCBs); wherein the PCBs include PCB 28, PCB 52, PCB101, PCB 81, PCB 77, PCB 123, PCB118, PCB 114, PCB 153, PCB 105, PCB138, PCB 126, PCB 167, PCB 156, PCB157, PCB 180, PCB 169 and PCB 189.

[0012] This invention also proposes a method for quantitative detection of trace or ultra-trace polychlorinated biphenyls (PCBs). The method involves first enriching the PCBs in the extracted sample using a solid-phase microextraction probe (coated with 3D-QS-COF), and then using GC-MS / MS to desorb and quantify the PCB-enriched solid-phase microextraction probe.

[0013] Preferably, the enrichment and extraction conditions for the solid-phase microextraction probe are: extraction temperature of 80℃, extraction for 50 min with stirring, and stirring speed of 400 rpm; the desorption conditions are: desorption temperature of 280℃ and desorption time of 5 min. The chromatographic column in the GC-MS / MS is an HP-5MS column, and its temperature program is: initial temperature of 100℃, followed by a temperature increase of 10℃·min after 1 min. -1 Heat to 200℃ and hold for 2 minutes; then increase the temperature by 8℃·min. -1The temperature was increased to 300℃ and held for 10 minutes. The beneficial effects are: the method constructed based on 3D-QS-COF and gas chromatography-mass spectrometry (GC-MS) technology has good linear correlation, low detection and quantification limits, high sensitivity, and good repeatability and stability. The material itself also exhibits good repeatability. When applied to real samples, it can achieve the enrichment and detection of trace or ultra-trace PCBs in actual samples, providing a new approach for the efficient analysis of trace PCBs in food and water samples, and has promising practical application prospects.

[0014] Compared with the prior art, the advantages of the present invention are as follows: This invention first synthesizes a three-dimensional organic framework material, and then uses sodium p-styrene sulfonate as a post-modification monomer to synthesize a quinoline-linked three-dimensional covalent organic framework material, 3D-QS-COF, via the Povarov reaction. This strategy effectively regulates the functional sites and pore structure of 3D COFs while stabilizing their structure and crystallinity, preventing pore collapse and loss of crystallinity. Furthermore, the 3D-QS-COF synthesized in this invention possesses numerous quinoline rings, benzene rings, and sodium sulfonate groups, providing a large number of binding sites. These sites allow for interactions with various polychlorinated biphenyls (PCBs) such as CH…N, NH…Cl, π…π, CH…O, Lp…π, and OH…Cl, laying the foundation for high-precision detection of trace or ultra-trace PCBs in food. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the synthesis of the present invention.

[0016] Figure 2 These are the Fourier transform infrared spectra of the 3D-COF and 3D-QS-COF of this invention.

[0017] Figure 3 These are the solid forms of 3D-COF and 3D-QS-COF of the present invention. 13 C10 NMR spectrum.

[0018] Figure 4 The PXRD characterization of the 3D-COF and 3D-QS-COF of this invention ( Figure 4 (c) and thermogravimetric diagram (see Figure 1) Figure 4 (Figure d) in the middle.

[0019] Figure 5 These are SEM images of the 3D-COF (see (a)) and 3D-QS-COF (see (b)) of this invention.

[0020] Figure 6 These are TEM and EDS characterization images of the 3D-COF and 3D-QS-COF of this invention. Figure 6In the image, (a) is a TEM image of 3D-COF, (b) is a TEM image of 3D-QS-COF, (c)-(e) are EDS images of 3D-COF, and (f)-(j) are EDS images of 3D-QS-COF.

[0021] Figure 7 These are characterization diagrams of the 3D-COF and 3D-QS-COF of this invention. Figure 5 In the image, (a) is the high-resolution full spectrum of 3D-COF and 3D-QS-COF, (b) and (c) are the high-resolution spectra of C 1s and N 1s of 3D-COF, respectively; (d)-(g) are the high-resolution spectra of C 1s, N 1s, S 2p and Na 1s of 3D-QS-COF, respectively; and (g)-(i) correspond to the contact angles of 3D-COF and 3D-QS-COF, respectively.

[0022] Figure 8 This is a SEM image of the 3D-QS-COF probe of the present invention.

[0023] Figure 9 This is a comparison of the repeatability and commercial applications of the 3D-QS-COF probe of this invention. Figure 9 (a) shows a comparison between the 3D-QS-COF probe and a commercial probe, and (b) shows the repeatability of the 3D-QS-COF probe.

[0024] Figure 10 This invention provides a spiked chromatogram and spiked recovery rate for detecting PCBs in tea beverages. Figure 10 (a) is the chromatogram, in which the peaks, in order of retention time from shortest to longest, correspond to PCB 28, PCB 52, PCB 101, PCB 81, PCB 77, PCB 123, PCB 118, PCB 114, PCB 153, PCB 105, PCB 138, PCB 167, PCB 156, PCB 157, PCB 180, and PCB 189; (b) is the spiked recovery rate.

[0025] Figure 11 These are XPS images of the 3D-QS-COF probe before and after adsorption in this invention. Figure 11 (a) is a high-resolution C1s comparison image before and after adsorption; (b) is a high-resolution N1s comparison image before and after adsorption.

[0026] Figure 12 This is the non-covalent force analysis of 3D-QS-COF and PCBs in Embodiment 2 of the present invention. Figure 1 . Figure 12In the middle, (a)-(i) correspond to PCB 28, PCB 52, PCB 101, PCB 81, PCB 77, PCB 123, PCB 118, PCB 114, and PCB 153 respectively.

[0027] Figure 13 This is the non-covalent force analysis of 3D-QS-COF and PCBs in Embodiment 2 of the present invention. Figure 2 . Figure 13 In the middle, (a)-(i) correspond to PCB 105, PCB 138, PCB 126, PCB 167, PCB 156, PCB 157, PCB 180, PCB 169, and PCB 189, respectively.

[0028] Figure 14 This is a concentration packing diagram of PCBs in the sample of this invention. Figure 14 (a) is a concentration packing diagram of 28 kinds of tea beverages, (b) is a concentration packing diagram of 29 kinds of tea leaves, and (c) is a concentration packing diagram of 23 kinds of flower teas. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings. This embodiment is implemented based on the technical solution of the present invention and provides detailed embodiments. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] It should be noted that all reagents used in this invention are commercially available, and all equipment used is standard laboratory equipment. The physicochemical properties of polychlorinated biphenyls (PCBs) in this invention are shown in Table 1.

[0031] Table 1. Physicochemical properties of the eighteen polychlorinated biphenyls in this invention. Continued from Table 1 Example 1: Quinoline-functionalized three-dimensional covalent organic framework material and probe of the present invention I. The quinoline-functionalized three-dimensional covalent organic framework material described in this invention is synthesized using a top-down strategy, combined with... Figure 1 The specific preparation method includes the following: The first step is to synthesize 3D-COF. Add 4',5'-bis(3,5-dimethylphenyl)-3',6'-dimethyl-[1,1':2',1″-triphenyl]3,3″,5,5″-tetracarboxaldehyde (i.e., DPTB-Me, 12.7 mg, 0.02 mmol), benzidine (14.7 mg, 0.08 mmol), 0.2 mL dioxane, 0.8 mL mesitylene, and 200 μL acetic acid (6.0 M) to a test tube (using Pyrex tubes), and sonicate for 10 min; The test tubes were degassed three times using a freeze-pump-thaw technique, then vacuum-sealed and reacted at 120℃ for 72 h. After the reaction, the precipitate was obtained by centrifugation, washed with DMF (10 mL × 3 times) and dioxane (10 mL × 3 times), then Soxhlet extracted with THF for 24 h, and dried under vacuum at 80 ℃ for 12 h to obtain a yellow-green powder of 3D-COF. The second step is to synthesize 3D-QS-COF. Add 3D-COF (20 mg), sodium p-styrenesulfonate (15 mg), 2,3-dichloro-5,6-dicyanobenzoquinone (6 mg), boron trifluoride ether (3 μL), and toluene (2 mL) to a Pyrex tube, sonicate for 5 min, and perform three freeze-pump-thaw cycles to degas the tube; seal with an open flame and react at 120 °C for 72 h. After the reaction was completed, the precipitate was filtered and washed successively with THF (10 mL × 2 times), DMF (10 mL × 2 times), and ethanol (10 mL × 2 times), followed by Soxhlet extraction with THF for 24 h; finally, it was dried under vacuum at 80 °C for 12 h to obtain a reddish-brown powder (i.e., 3D-QS-COF), with the following structural formula: .

[0032] II. The solid-phase microextraction probe described in this invention The solid-phase microextraction probe (i.e., the 3D-QS-COF probe) described in this invention is prepared by curing the 3D-QS-COF obtained in this embodiment onto a stainless steel wire. The specific preparation method includes the following: Cut several 5 cm long and 120 μm diameter stainless steel wires (i.e., SSW), wash them sequentially with ultrapure water, methanol and acetone for 30 min each, and air dry them at room temperature for later use; grind 3D-QS-COF into powder for later use. The SSW was vertically immersed in PDMS adhesive solution (PDMS adhesive was prepared by mixing polydimethylsiloxane (PDMS) and initiator at a mass ratio of 10:1, and then PDMS adhesive and n-hexane were mixed at a mass ratio of 1 g:1 mL to obtain PDMS adhesive solution) for 30 s, and then slowly and uniformly pulled out of the solution. Immediately after pulling out, it was inserted into 3D-QS-COF powder and gently rotated in one direction to obtain a uniform coating. Then it was cured at 160℃ for 30 min. This process was repeated three times, and the last time it was dried at 160℃ overnight to obtain the 3D-QS-COF probe. To protect the probe, excess material is scraped off after drying, leaving approximately 1 cm of coating. The prepared fiber is then placed in an SPME sleeve. Before use, the probe is aged at 300°C for 30 minutes (aging can be done at the gas chromatograph inlet) to activate the 3D-QS-COF probe of this invention.

[0033] Similarly, repeat the above preparation steps to obtain a 3D-COF probe, which can be used as a comparison probe.

[0034] III. Characterization of Materials and Probes 1. The Fourier transform infrared (FT-IR) spectra of 3D-COF and 3D-QS-COF are shown in [reference needed]. Figure 2 .Depend on Figure 2 It can be seen that 3D-COF is at 1618 cm. -1 The imine bond absorption peak that appears at the position corresponds to the stretching vibration absorption peak of the imine bond C=N in 3D-COF, indicating that the Schiff base condensation reaction has successfully occurred. In the FT-IR spectrum of 3D-QS-COF, 1600 cm⁻¹ -1 The absorption peak at 1035 cm⁻¹ is attributed to the C=N stretching vibration absorption peak of quinoline, indicating the formation of quinoline bonds; -1 1012 cm -1 The absorption peak at point O is the stretching vibration of O=S=O, confirming the successful modification of 3D-QS-COF.

[0035] 2. Solids of 3D-COF and 3D-QS-COF 13 The C nuclear magnetic resonance spectrum is shown in [the image]. Figure 3 .Depend on Figure 3 It can be seen that 3D-COF's 13 CNMR spectroscopy showed a carbon signal peak at 155 ppm (signal 8 in the figure) indicating the formation of an imine bond; after modification with sodium styrene sulfonate, the 3D-QS-COF... 13 The disappearance of the imine bond signal at 155 ppm and the appearance of the quinoline carbon peak at 149 ppm in the C NMR spectrum prove that the imine bond was successfully converted into quinoline, confirming the successful synthesis of 3D-QS-COF.

[0036] 3. The PXRD characterization results of 3D-COF and 3D-QS-COF are shown in [reference needed]. Figure 4 Figure (a) shows that 3D-COF has a strong peak at 4.05°, which is attributed to the (011) peak. The relatively weaker peaks at 5.68°, 8.11°, 9.26°, 13.01°, 14.70° and 16.37° can be attributed to the (101), (110), (022), (121), (200) and (220) peaks, respectively. 3D-QS-COF has a strong peak at 4.06°, which is attributed to the (011) peak. The relatively weaker peaks at 5.65°, 8.19°, 9.34°, 13.12°, 14.80° and 16.42° can be attributed to the (101), (110), (022), (121), (200) and (220) peaks, respectively. PXRD characterization results show that the crystal framework of the post-modified 3D-QS-COF is consistent with that of 3D-COF.

[0037] 4. The TGA curves for 3D-QS-COF and 3D-COF are shown below. Figure 4 Figure (d) shows that, within the temperature range of 45-300℃, the weight loss of 3D-QS-COF is higher than that of 3D-COF, which is due to the evaporation of water in the molecular structure of the material. At 300-500℃, both materials experience significant weight loss, but the weight loss of 3D-COF is significantly greater than that of 3D-QS-COF. These results indicate that 3D-QS-COF possesses superior thermal stability.

[0038] 5. SEM images of 3D-QS-COF and 3D-COF are shown below. Figure 5 .Depend on Figure 5 It can be seen that the 3D-COF has a uniform morphology and is a lamellar structure; the morphology of the quinoline-linked 3D-QS-COF modified with sodium styrene sulfonate is an irregular lamellar structure, and the morphology of COF before and after modification does not change much.

[0039] 6. TEM and EDS images of 3D-QS-COF and 3D-COF are shown below. Figure 6 As shown in Figure 6, the uniform distribution of C, N, and O on the surface of 3D-COF indicates that the synthesis of 3D-COF was successful; the uniform distribution of C, N, O, S, and Na elements on the surface of 3D-QS-COF indicates that the sodium styrene sulfonate monomer has been successfully modified onto the surface of 3D-COF.

[0040] 7. XPS analysis results for 3D-QS-COF and 3D-COF are shown in [reference needed]. Figure 7As shown in the figure, XPS analysis confirmed the presence of C 1s, N 1s, and O 1s in the 3D-COF framework, and C 1s, N 1s, O 1s, S 2p, and Na 1s in the 3D-QS-COF framework (see figure). Figure 7 (a)

[0041] Three binding energies were observed in the C 1s high-resolution spectrum of the 3D-COF: 289.9 eV, 287.3 eV, and 285.8 eV. The binding energies of 289.9 eV and 285.8 eV are attributed to C=N and C / C=C bonds, respectively, while the binding energy of 287.3 eV is attributed to the C=O bond (see [link to relevant documentation]). Figure 7 (b)); The N 1s high-resolution spectrum of 3D-COF shows a peak with a binding energy of 399.7 eV, which is attributed to the C=N bond (see [reference]). Figure 7 (c)

[0042] The high-resolution C 1s spectrum of the 3D-QS-COF shows four binding energies: 285.4 eV, 283.2 eV, 281.9 eV, and 281.3 eV. The binding energies of 285.4 eV and 281.3 eV are attributed to C=N and C / C=C bonds, respectively; the binding energy of 283.2 eV is attributed to C=O bonds; and the binding energy of 281.9 eV is attributed to C=S bonds (see...). Figure 7 (d) The N 1s high-resolution spectrum of the 3D-QS-COF shows two binding energies, with peaks at 401.2 eV and 399.03 eV, respectively. The binding energy of 401.2 eV is attributed to the Quinoline bond, and the binding energy of 399.03 eV is attributed to the C=N bond (see [reference]). Figure 7 (e)); The S 2p high-resolution spectrum of the 3D-QS-COF shows two binding energies, with peaks at 166.1 eV and 164.9 eV, respectively. The binding energy of 166.1 eV is attributed to the SO bond, and the binding energy of 164.9 eV is attributed to the CS bond (see [reference]). Figure 7 (f)); The binding energy of Na 1s in the high-resolution spectrum of 3D-QS-COF is 1069.1 eV (see [reference]). Figure 7 (g)

[0043] 8. The hydrophilic and hydrophobic properties of 3D-QS-COF and 3D-COF were analyzed using contact angle (CA) experiments. The results showed that the contact angle of 3D-COF was 109.1°, while that of 3D-QS-COF was 103.5°, indicating that the hydrophobicity of 3D-QS-COF containing quinoline groups was slightly reduced. (See details below.) Figure 7 (h) and (i).

[0044] 9. N2 adsorption isotherm analysis was performed on 3D-COF and 3D-QS-COF at 77 K. The results showed that the specific surface area of ​​3D-QS-COF was 650 m². 2 ·g -1 The pore size of 3D-COF is 18 Å, while that of 3D-QS-COF is 16 Å. The pore size of the modified 3D-QS-COF is relatively smaller than that of 3D-COF.

[0045] 10. The 3D-QS-COF probe was characterized by SEM, and the results are shown in [Figure number missing]. Figure 8 .Depend on Figure 8 It can be seen that the diameter of the 3D-QS-COF probe is 330 μm and the coating thickness of the 3D-QS-COF probe is 105 μm.

[0046] Example 2: A method for quantitative detection of trace or ultra-trace polychlorinated biphenyls I. This invention, based on 3D-QS-COF probe and GC-MS / MS technology, constructs a method for detecting trace or ultra-trace polychlorinated biphenyls (PCBs). The method includes the following detection steps: The first step is to pretreat the sample. For tea beverages, simply pass the sample through a 0.22µm membrane; for solid tea products such as tea leaves and flower tea, add the sample to boiling water (e.g., add 150 mL of boiling water to 3g of sample), let it stand for 3 hours, and then filter it through a 0.22µm filter membrane. The second step is to take a certain volume of sample solution (e.g., 10 mL) and place it in a glass bottle. Under water bath conditions, the PCBs in the sample are extracted using headspace extraction mode. The probe used is the 3D-QS-COF probe of this invention. The extraction time is 50 min, the extraction temperature is 80 ℃, and the stirring speed is 400 rpm. The third step, after extraction, is to perform desorption and analysis using GC-MS / MS: the probe is pulled out and immediately inserted into the gas chromatograph injection port for desorption, the injection port temperature is 280 ℃, and the desorption time is 5 min; The gas chromatography column used in GC-MS / MS was an HP-5MS column (30 m × 0.25 mm id × 0.25 µm), with an injection port temperature of 280℃; the initial column temperature was 100℃, and the column temperature was increased by 10℃·min after 1 min. -1 Heat to 200℃ and hold for 2 minutes; then increase the temperature by 8℃·min. -1 Heat to 300℃ and hold for 10 minutes. The fourth step is to calculate the content of polychlorinated biphenyls (PCBs) in the sample based on the standard curve of PCBs and the results of the third step.

[0047] II. Reliability Analysis of the Method for Detecting Trace or Ultra-Trace Polychlorinated Biphenyls Constructed in This Invention 1. Linear range, limit of quantitation, and limit of detection of polychlorinated biphenyls (PCBs) First, standard mixed stock solutions of eighteen PCBs were prepared. These eighteen PCBs included PCB 28, PCB 52, PCB101, PCB 81, PCB 77, PCB 123, PCB 118, PCB 114, PCB 153, PCB 105, PCB 138, PCB 126, PCB 167, PCB 156, PCB 157, PCB 180, PCB 169, and PCB 189, with a concentration of 10 μg·L⁻¹ for each PCB. -1 Dilute with ultrapure water to obtain standard solutions with different concentration gradients; Next, take 10 mL of standard solution in a glass bottle, and perform detection and analysis on the standard solution according to the second and third steps in the first item. Plot the standard curve for each PCB, and the results are shown in Table 2.

[0048] Table 2 As shown in Table 2, the linear range of the standard curves for the eighteen types of PCBs is 0.01-100 ng·L. -1 R of all analytes 2 All values ​​were greater than 0.99. The results indicate that all eighteen PCBs exhibited good responses within the linear range. The limits of detection (LODs) and quantitation (LOQs) of the PCBs were determined using the signal-to-noise ratio (S / N). The LODs (S / N=3) and LOQs (S / N=10) for the eighteen PCBs ranged from 0.0012 to 0.0081 ng·L⁻¹. -1 And 0.0040-0.0271 ng·L -1 The results show that the detection method constructed in this invention can be used for the quantitative detection of trace levels of PCBs.

[0049] 2. Accuracy and reproducibility of the detection method of the present invention Analysis of the peak areas of eighteen PCBs revealed that the relative standard deviations (RSDs) for intra-day (n=3), inter-day (n=3), and inter-probe (n=3) results were 0.28-6.82%, 0.11-7.65%, and 0.51-5.00%, respectively (see Table 2). This demonstrates that the method of this invention exhibits extremely high repeatability and consistency within a single day, inter-day, and across different probes, thereby ensuring the reliability of the detection results.

[0050] 3. The enrichment efficiency of the probe of the present invention was evaluated using enrichment factors (EFs), and the results are shown in Table 2. As can be seen from Table 2, the EFs range of the present invention for eighteen types of PCBs is 7002-13333, which indicates the significant enrichment ability generated by the specific interaction between the 3D-QS-COF of the present invention and PCBs, ensuring detection sensitivity.

[0051] 4. The commercial value and reproducibility of the 3D-QS-COF probe of this invention To evaluate the commercial potential of the 3D-QS-COF probe, this invention investigated the enrichment and extraction performance of the 3D-QS-COF probe and commercial fibers 50 / 30 µm DVB / CAR / PDMS, 100 µm PDMS, and 65 µm PDMS / DVB. The results are shown in [Figure number missing]. Figure 9 (a) As shown in the figure, the 3D-QS-COF probe of this invention exhibits extraction efficiencies of 5.3-36.4 times that of DVB / CAR / PDMS, 3.1-5.0 times that of PDMS, and 3.0-4.3 times that of PDMS / DVB. Compared with commercial probes, 3D-QS-COF demonstrates superior extraction capabilities for PCBs.

[0052] The 3D-QS-COF probe of this invention was used to repeatedly extract standard solutions of eighteen PCBs to examine its reusability. The results are shown in […]. Figure 9 (b) As shown in the figure, the extraction efficiency of the 3D-QS-COF probe of the present invention did not change significantly after 70 uses, which proves that the 3D-QS-COF fiber has good stability.

[0053] 5. Verify the method of the present invention using a spiked recovery experiment. This invention verifies the accuracy and applicability of the method established in this invention in actual sample matrices through spiked recovery experiments, with spiked concentrations of 5 ng·L⁻¹. -1 20 ng·L -1 50 ng·L -1 Spiked standard solutions were added to tea beverages, and spiked recovery experiments were conducted. The results are shown in Table 3 and [Table data missing]. Figure 10The retention times for the eighteen PCBs are as follows: PCB 28: 13.967 min; PCB 52: 14.962 min; PCB 101: 17.387 min; PCB 81: 18.127 min; PCB 77: 18.402 min; PCB 123: 18.946 min; PCB 118: 19.043 min; PCB 114: 19.301 min; PCB 153: 19.593 min; PCB 105: 19.685 min; PCB 138: 20.258 min; PCB 167: 20.983 min; PCB 156: 21.518 min; PCB 157: 21.630 min; PCB 180: 21.899 min; and PCB 189: 23.258 min.

[0054] From Table 3 and Figure 10 It can be seen that the spiked recoveries of the present invention in tea beverages were 82.7-117.2% (RSDs in the range of 0.31-9.85%). The results verify the accuracy and applicability of the method of the present invention for quantifying PCBs in tea matrix.

[0055] In summary, the method developed in this invention exhibits good linearity for eighteen types of PCBs, with high accuracy and reproducibility. The probe also has good enrichment efficiency and reusability, making it suitable for high-precision quantitative detection of trace PCBs and demonstrating promising practical applications.

[0056] III. Adsorption Mechanism of 3D-QS-COF on PCBs in this Invention 1. This invention utilizes XPS analysis to study the changes in elemental binding energies before and after adsorption of 3D-QS-COF. The results are shown in [Figure number missing]. Figure 11 .Depend on Figure 11 As can be seen from the high-resolution C 1s spectrum, after PCBs adsorption by 3D-QS-COF, the C 1s peak of C=N shifted from 285.4 eV to 285.8 eV; and in the high-resolution N 1s spectrum, after PCBs adsorption by 3D-QS-COF, the N 1s peaks of C=N and quinoline shifted from 398.9 eV and 400.2 eV to 399.6 eV and 401.3 eV, respectively. These results indicate that the quinoline ring plays a significant role in the enrichment of PCBs.

[0057] 2. This invention employs quantum chemical calculation methods (based on density functional theory, DFT) to perform structural optimization, molecular docking, and visualization analysis of non-covalent interactions (NCI) on eighteen PCB molecules. The results are shown in [Figure number missing]. Figure 12 and Figure 13As shown in the figure, the quinoline ring, benzene ring, and sodium sulfonate group of 3D-QS-COF can form various interactions with the chlorine atoms and benzene ring structures in 18 PCB molecules. These include CH…N, CH…π, and NH…Cl interactions between the quinoline ring and the analytes (PCB52, 77, 157, etc.); π…π, CH…Cl, CH…O, and Lp…π interactions between the benzene ring structure and the analytes (PCB28, 118, 138, etc.); and OH…Cl and CH…O interactions between the sodium sulfonate and the analytes (PCB81, 156, etc.). This enables the specific recognition of PCBs during the 3D-QS-COF extraction process, further demonstrating the potential of 3D-QS-COF for PCBs.

[0058] Example 3: Application of the detection method constructed in this invention in actual samples. The method constructed in this invention was used to enrich and detect PCBs in 28 kinds of tea beverages, 29 kinds of tea leaves, and 23 kinds of flower teas. Specific methods and steps are described in the first item of Example 2. Detection results are shown in Table 3. Figure 14 .

[0059] Table 3. Detection of PCBs in the three types of tea samples in this embodiment. Continued from Table 3 Depend on Figure 14 It can be seen that tea beverages have the highest PCB content. Table 3 shows that the highest detection rate of PCB 28 in tea beverages is 71.43%, with a detection range of 0-1.34 ng·L⁻¹. -1 The highest detection rate of PCB 101 in tea was 51.72%, with a detection range of 0-1.19 ng·L⁻¹. -1 The highest detection rate of PCB 52 in flower tea was 37.5%, with a detection range of 0-1.39 ng·L⁻¹. -1 Although some PCBs were detected in tea beverages, tea leaves, and flower teas, the concentration of PCBs in all detected samples did not exceed the relevant standards.

[0060] In summary, the 3D-QS-COF material of this invention possesses multiple interaction sites due to the conjugated structure of the quinoline ring and benzene ring in 3D-QS-COF, promoting interactions with 18 types of PCBs such as CH…N, NH…Cl, π…π, CH…O, and Lp…π, significantly enhancing the adsorption performance of 3D-QS-COF for these 18 types of PCBs. The method constructed based on 3D-QS-COF and gas chromatography-mass spectrometry (GC-MS) exhibits good linear correlation, low limits of detection and quantitation, high sensitivity, and excellent repeatability and stability. The material itself also demonstrates good repeatability. Its application in real samples can achieve the enrichment and detection of trace or ultra-trace PCBs, providing a new approach for the efficient analysis of trace PCBs in food and water samples, and has promising practical applications.

Claims

1. A quinolinyl-functionalized three-dimensional covalent organic framework material, characterized in that: The quinolinyl-functionalized three-dimensional covalent organic framework material is obtained by modifying 3D-COF with sodium p-styrene sulfonate, and is designated as 3D-QS-COF. 3D-COF is copolymerized from benzidine and 4',5'-bis(3,5-dimethylphenyl)-3',6'-dimethyl-[1,1':2',1″-triphenyl]3,3″,5,5″-tetracarboxylic aldehyde. The structural formulas of 3D-COF and 3D-QS-COF are as follows: .

2. The quinoline-functionalized three-dimensional covalent organic framework material according to claim 1, characterized in that: The post-modification of 3D-COF with sodium p-styrene sulfonate includes the following steps: 2,3-dichloro-5,6-dicyanobenzoquinone, boron trifluoride ether, and toluene are added to 3D-COF and sodium p-styrene sulfonate in a reaction tube. After degassing by freezing-thawing cycle, the tube is sealed and reacted at 100℃~140℃ for 48 h~96 h. After the reaction, the tube is washed sequentially with THF, DMF, and ethanol, followed by Soxhlet washing with THF and drying to obtain 3D-QS-COF.

3. The quinoline-functionalized three-dimensional covalent organic framework material according to claim 1, characterized in that: In the synthesis of 3D-COF, the molar ratio of benzidine to 4',5'-bis(3,5-dimethylphenyl)-3',6'-dimethyl-[1,1':2',1″-triphenyl]3,3″,5,5″-tetracarboxaldehyde was 4:1, and the reaction conditions were 100℃~140℃ for 48 h~96 h.

4. A solid-phase microextraction probe, comprising a needle body and a coating applied to the needle body, characterized in that: The coating uses the quinoline-functionalized three-dimensional covalent organic framework material as described in any one of claims 1-3.

5. The application of the solid-phase microextraction probe according to claim 4 in the quantitative detection of trace or ultra-trace polychlorinated biphenyls; wherein, Polychlorinated biphenyls include PCB 28, PCB 52, PCB 101, PCB 81, PCB 77, PCB 123, PCB 118, PCB 114, PCB 153, PCB 105, PCB 138, PCB 126, PCB 167, PCB 156, PCB 157, PCB 180, PCB 169 and PCB189.

6. A method for quantitative detection of trace or ultra-trace polychlorinated biphenyls, characterized in that: The method described herein uses the solid-phase microextraction probe described in claim 4 to enrich polychlorinated biphenyls (PCBs) in the extracted sample, and then uses GC-MS / MS to desorb and quantify the solid-phase microextraction probe enriched with PCBs.

7. The method for quantitative detection of trace or ultra-trace polychlorinated biphenyls according to claim 6, characterized in that: The enrichment and extraction conditions are as follows: extraction temperature is 80℃, extraction is performed for 50 min under stirring conditions, and stirring speed is 400 rpm; the desorption conditions are as follows: desorption temperature is 280℃, and desorption time is 5 min.

8. The method for quantitative detection of trace or ultra-trace polychlorinated biphenyls according to claim 6, characterized in that: The GC-MS / MS uses an HP-5MS column, and its temperature program is as follows: the initial temperature of the column is 100℃, and after 1 min, the temperature is increased at 10℃·min. -1 Heat to 200℃ and hold for 2 minutes; then increase the temperature by 8℃·min. -1 Heat to 300℃ and hold for 10 minutes.

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