A solid phase microextraction probe material, its preparation method and application

Abstract

The application patent belongs to the technical field of environmental monitoring, and specifically discloses a solid-phase microextraction probe material, a preparation method thereof and application of the solid-phase microextraction probe material in preparation of a solid-phase microextraction probe coating for detecting disinfection by-products and glucocorticoids. The solid-phase microextraction probe material provided by the scheme has a simple preparation process and a lower cost than the price of existing commercial solid-phase microextraction probes. By introducing carboxyl functional groups, the adsorption sites are enriched, and the pore elasticity is increased, so that the adsorption capacity for polar trihalomethane disinfection by-products and glucocorticoids is significantly improved, and rapid, efficient and sensitive sample pretreatment is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of environmental monitoring, and more specifically, relates to a solid-phase microextraction probe material, its preparation method, and its application in the preparation of solid-phase microextraction probe coatings for detecting disinfection byproducts and glucocorticoids. Background Technology

[0002] Urban drinking water sources often contain residual disinfection byproducts such as trihalomethanes after disinfection treatment, and trace amounts of glucocorticoids are also commonly found in the water. Glucocorticoids, including common compounds such as hydrocortisone and prednisolone, have anti-inflammatory and anti-allergic pharmacological effects and are widely used to treat inflammatory, allergic, and autoimmune diseases in livestock, poultry, and humans. In addition to their therapeutic effects, glucocorticoids can also improve feed conversion rates and are used as growth promoters in mariculture. The widespread use of glucocorticoids has led to their entry into environmental and agricultural water systems. Studies have shown that even at extremely low concentrations, residual glucocorticoids in the aquatic environment can have adverse effects on humans and aquatic organisms. Therefore, establishing highly sensitive analytical methods for glucocorticoids in environmental water is crucial to ensuring water quality safety.

[0003] Trihalomethanes are a class of organic compounds with the molecular formula CHX3 (where X is a halogen), commonly including chloroform, bromoform, and iodoform. Trihalomethanes are highly volatile, easily evaporating during sample processing and causing sample loss. In some complex sample matrices, trihalomethanes are difficult to completely precipitate and extract, leading to inaccurate detection results. Currently, commonly used techniques for detecting trihalomethanes include gas chromatography (GC), liquid chromatography (LC), spectrometry, and electrochemical detection techniques. Different detection techniques have their own advantages, disadvantages, and applicable ranges. In practical applications, it is necessary to select the appropriate detection method and technique based on factors such as sample type, detection purpose, and accuracy requirements. Among them, gas chromatography-mass spectrometry (GC-MS) can accurately determine the molecular weight and structure of trihalomethanes and glucocorticoids, obtaining more accurate detection results.

[0004] Gas chromatography-mass spectrometry (GC-MS) has the following requirements for the analyzed samples: high sample purity: the analyte should be sufficiently pure, free of impurities and interfering substances to avoid affecting the detection results; appropriate sample concentration: the sample concentration should be high enough, but not too high, to avoid damaging the instrument and overloading it, while ensuring the accuracy and sensitivity of the detection results. Therefore, for the quantitative analysis of trihalomethanes and glucocorticoids in actual samples, water samples need to undergo pretreatment and sample preparation, such as filtration, extraction, and concentration, to better separate, purify, and quantify the analysis. However, this pretreatment method is time-consuming and labor-intensive, and consumes a large amount of organic solvents, causing pollution. Solid phase microextraction (SPME) technology is a rapid, efficient, and sensitive sample pretreatment technique that can be applied to the extraction and analysis of trihalomethanes in water samples. However, in practical applications, the following challenges exist: the concentrations of trihalomethanes and glucocorticoids in water are usually very low, requiring improvements in the extraction efficiency of the SPME coating to meet the analytical requirements. Summary of the Invention

[0005] The present invention aims to overcome the defects of the prior art and provide a solid-phase microextraction probe material. The solid-phase microextraction probe material utilizes carboxyl functional groups to make its surface adsorption sites more abundant and its pore elasticity better, thereby significantly improving its adsorption capacity.

[0006] Another object of the present invention is to provide a method for preparing the solid-phase microextraction probe coating.

[0007] Another object of the present invention is to provide the application of the solid-phase microextraction probe coating.

[0008] To achieve the above objectives, the technical solution is as follows:

[0009] A vinyl-containing covalent organic framework (BTA-DVACOF) was synthesized by covalently reacting the monomer 1,3,5-pyromellitictriamine (BTA) with 2,5-divinyl-terephthalaldehyde (DVA). Further, via the Heck reaction, 4-bromobenzoic acid was used to carboxylate the vinyl sites on COF-V, generating a carboxyl-functionalized covalent organic framework (BTA-DVA-COOH COF). Its unit structure is shown below. Figure 1 As shown, the synthesized BTA-DVA-COOH COF was fixed onto a stainless steel wire using PDMS adhesive via a bonding method, resulting in a solid-phase microextraction probe based on BTA-DVA-COOH COF, which can be used for ultra-efficient sample pretreatment of trihalomethanes (THMs) and glucocorticoids in water.

[0010] As a flexible ligand, the introduction of bromobenzoic acid brings two advantages. Firstly, the carboxyl groups introduced onto the COF pore walls enrich the adsorption sites, enhancing the adsorption capacity for THMs and glucocorticoids. More importantly, the overlapping of benzoic acid groups on the COF pore walls creates cavities smaller than the intrinsic pore size of the COF. Due to the flexible stretching of the carboxyl functional groups, these smaller cavities possess good elasticity and the ability to retain small-sized THMs.

[0011] The preparation method of BTA-DVA-COOH COF includes the following steps:

[0012] Step S1: Mix 1,3,5-pyromellitic triamine and 2,5-divinyl terephthalaldehyde, and add a mixture of o-dichlorobenzene, nBuOH and acetic acid. After sealing and standing, take the precipitate, extract it with tetrahydrofuran and dry it to obtain BTA-DVACOF.

[0013] Step S2: Dissolve the BTA-DVA COF in n-methylpyrrolidone to obtain a suspension. Add a mixture of 4-bromobenzoic acid, Pd(OAc)2, N,N-dimethyl-β-alanine hydrochloride, and K2CO3 to the suspension. Wash, extract, and dry to obtain BTA-DVA-COOH COF.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The solid-phase microextraction probe material provided in this solution has a simple preparation process and is less expensive than existing commercial solid-phase microextraction probes. By introducing carboxyl functional groups, the adsorption sites are enriched and the porosity is increased, thereby significantly improving the adsorption capacity for polar trihalomethane disinfection byproducts and glucocorticoids, achieving rapid, efficient and sensitive sample pretreatment. Attached Figure Description

[0016] Figure 1 This is the unit structure diagram of the BTA-DVA-COOH COF scheme.

[0017] Figure 2 This is a PXRD comparison chart of the BTA-DVA COF of this scheme and the simulated BTA-DVA COF.

[0018] Figure 3 Infrared images of monomeric BTA, DVA, and BTA-DVA COF.

[0019] Figure 4 This is a SEM image of BTA-DVA COF.

[0020] Figure 5The image shows a comparison of the PXRD values ​​of the proposed BTA-DVA-COOH COF and the simulated BTA-DVA-COOH COF.

[0021] Figure 6 Infrared spectra of BTA-DVA and BTA-DVA-COOH COF.

[0022] Figure 7 This is a SEM image of BTA-DVA-COOH COF.

[0023] Figure 8 This is a SEM image of the BTA-DVA probe.

[0024] Figure 9 This is a SEM image of the BTA-DVA-COOH probe.

[0025] Figure 10 A comparison of the extraction effects of BTA-DVA probe, BTA-DVA-COOH probe and commercial SPME probe combination on THMs.

[0026] Figure 11 Linearity graph of BTA-DVA-COOH probe combined with GC-MS for the detection of THMs solutions with concentrations of 0-10000 ng / L.

[0027] Figure 12 The relationship between peak area and analyte concentration (logarithmic value) after extraction with BTA-DVA-COOH probe is shown.

[0028] Figure 13 This study compares the extraction efficacy of BTA-DVA-COOH probes and commercial SPME probes on prednisolone. Detailed Implementation

[0029] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this invention. To better illustrate the following embodiments, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product; it is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0030] Example 1: Synthesis scheme 1 for BTA-DVA-COOH COF material

[0031] Synthesis of BTA-DVA COF: 2,5-Divinyl-terephthalaldehyde (DVA, 55.9 mg, 0.3 mmol) and 1,3,5-pyromellitic triamine (TAPB, 70.3 mg, 0.2 mmol) were loaded into a capped quartz tube with side tubes. A mixture of 1 mL o-dichlorobenzene, 1 mL nBuOH, and 0.2 mL 6M acetic acid (volume ratio 5:5:1) was then added. The tube was sealed under anhydrous and oxygen-free conditions and allowed to stand at room temperature for 3 days. The precipitate was separated by filtration and Soxhlet extraction with tetrahydrofuran (THF) for 24 h to ensure removal of unreacted starting materials and residual oligomers. The product BTA-DVA COF was obtained by drying in a vacuum oven at 80 °C. The obtained BTA-DVA COF was characterized by powder X-ray diffraction (PXRD). Figure 2 ) and infrared characterization ( Figure 3 This demonstrates the successful synthesis of BTA-DVA COF. The morphology of BTA-DVA COF was observed using scanning electron microscopy (SEM), as shown below. Figure 4 As shown, the synthesized BTA-DVA COF has a uniform nanosphere morphology.

[0032] Synthesis of BTA-DVA-COOH COF: 60 mg of the synthesized BTA-DVA COF powder was dissolved in 100 mL of n-methylpyrrolidone, and then ultrasonically pulverized for 30 min to obtain highly dispersed BTA-DVA COF. Subsequently, a mixture of 4-bromobenzoic acid (50 mg), Pd(OAc)₂ (2 mg), N,N-dimethyl-β-alanine hydrochloride (1 mg), and K₂CO₃ (126.17 mg) was added to the BTA-DVA COF suspension. After stirring at 130 °C for 10 h under an argon atmosphere, the mixture was washed with pure water and extracted with diethyl ether for 24 h using a Soxhlet extractor to ensure the removal of unreacted starting materials. The product was then vacuum dried at 80 °C to obtain the final product. The obtained BTA-DVA-COOH COF was characterized by PXRD and IR spectroscopy, and the results are as follows: Figure 5 , Figure 6 As shown, the successful synthesis of BTA-DVA-COOHCOF is demonstrated. The morphology was observed using SEM, as shown below. Figure 7 As shown, the synthesized BTA-DVA-COOH COF still maintains a uniform nanosphere morphology.

[0033] Example 2: Synthesis Scheme 2 for BTA-DVA-COOH COF Material

[0034] Synthesis of BTA-DVA COF: 1,3,5-Pyromellitic triamine and 2,5-divinyl terephthalaldehyde were loaded into a capped quartz tube with side tubes at a molar ratio of 1:3. Subsequently, a mixture of o-dichlorobenzene, nBuOH, and 6M acetic acid was added at a volume ratio of 3:10:1. The tube was sealed under anhydrous and oxygen-free conditions and allowed to stand at room temperature for 3 days. The precipitate was separated by filtration and Soxhlet extraction with tetrahydrofuran (THF) for 24 h to ensure removal of unreacted starting materials and residual oligomers. The product BTA-DVA COF was obtained after drying in a vacuum oven at 80 °C. Powder X-ray diffraction (PXRD) and infrared spectroscopy characterized the obtained BTA-DVA COF, confirming its successful synthesis. Scanning electron microscopy (SEM) revealed that the morphology of BTA-DVA COF consisted of uniform nanospheres.

[0035] Synthesis of BTA-DVA-COOH COF: 60 mg of the synthesized BTA-DVA COF powder was dissolved in 100 mL of n-methylpyrrolidone, and then ultrasonically pulverized for 30 min to obtain highly dispersed BTA-DVA COF. Subsequently, a mixture of 4-bromobenzoic acid (30 mg), Pd(OAc)₂ (1 mg), N,N-dimethyl-β-alanine hydrochloride (1 mg), and K₂CO₃ (100 mg) was added to the BTA-DVA COF suspension. After stirring at 130 °C for 15 h under an argon atmosphere, the mixture was washed with pure water and extracted with diethyl ether for 18 h using a Soxhlet extractor to ensure the removal of unreacted starting materials. The product was then dried under vacuum at 80 °C to obtain the final product. The obtained BTA-DVA-COOH COF was characterized by PXRD and IR, confirming the successful synthesis of BTA-DVA-COOH COF. SEM observation revealed that the synthesized BTA-DVA-COOH COF maintained a uniform nanosphere morphology.

[0036] Example 3: Synthesis scheme 3 for BTA-DVA-COOH COF material

[0037] Synthesis of BTA-DVA COF: 1,3,5-Phenylacetyltriamine and 2,5-divinyl terephthalaldehyde were loaded into a capped quartz tube with side tubes in a molar ratio of 5:6. Subsequently, a mixture of o-dichlorobenzene, nBuOH, and 6M acetic acid was added in a volume ratio of 10:3:1. The tube was sealed under anhydrous and oxygen-free conditions and allowed to stand at room temperature for 2 days. The precipitate was separated by filtration and Soxhlet extraction with tetrahydrofuran (THF) for 24 h to ensure removal of unreacted starting materials and residual oligomers. The product BTA-DVA COF was obtained after drying in a vacuum oven at 80 °C. Powder X-ray diffraction (PXRD) and infrared spectroscopy characterized the obtained BTA-DVA COF, confirming its successful synthesis. Scanning electron microscopy (SEM) revealed that the morphology of BTA-DVA COF consisted of uniform nanospheres.

[0038] Synthesis of BTA-DVA-COOH COF: 60 mg of the synthesized BTA-DVA COF powder was dissolved in 100 mL of n-methylpyrrolidone, and then ultrasonically pulverized for 30 min to obtain highly dispersed BTA-DVA COF. Subsequently, a mixture of 4-bromobenzoic acid (80 mg), Pd(OAc)₂ (3 mg), N,N-dimethyl-β-alanine hydrochloride (1 mg), and K₂CO₃ (150 mg) was added to the BTA-DVA COF suspension. After stirring at 130 °C for 8 h under an argon atmosphere, the mixture was washed with pure water and extracted with diethyl ether for 36 h using a Soxhlet extractor to ensure the removal of unreacted starting materials. The product was then dried under vacuum at 80 °C to obtain the final product. The obtained BTA-DVA-COOH COF was characterized by PXRD and IR, confirming the successful synthesis of BTA-DVA-COOH COF. SEM observation revealed that the synthesized BTA-DVA-COOH COF maintained a uniform nanosphere morphology.

[0039] Example 4: Synthesis scheme 4 for BTA-DVA-COOH COF material

[0040] Synthesis of BTA-DVACOF: 1,3,5-Phenylacetyltriamine and 2,5-divinyl terephthalaldehyde were loaded into a capped quartz tube with side tubes in a molar ratio of 2:3. Subsequently, a mixture of o-dichlorobenzene, nBuOH, and 6M acetic acid was added in a volume ratio of 3:5:1. The tube was sealed under anhydrous and oxygen-free conditions and allowed to stand at room temperature for 3 days. The precipitate was separated by filtration and Soxhlet extraction with tetrahydrofuran (THF) for 24 h to ensure removal of unreacted starting materials and residual oligomers. The product BTA-DVA COF was obtained after drying in a vacuum oven at 80 °C. Powder X-ray diffraction (PXRD) and infrared spectroscopy characterization of the obtained BTA-DVA COF confirmed its successful synthesis. Scanning electron microscopy (SEM) revealed that the morphology of BTA-DVA COF consisted of uniform nanospheres.

[0041] Synthesis of BTA-DVA-COOH COF: 60 mg of the synthesized BTA-DVA COF powder was dissolved in 100 mL of n-methylpyrrolidone, and then ultrasonically pulverized for 30 min to obtain highly dispersed BTA-DVA COF. Subsequently, a mixture of 4-bromobenzoic acid (80 mg), Pd(OAc)₂ (2 mg), N,N-dimethyl-β-alanine hydrochloride (1 mg), and K₂CO₃ (120 mg) was added to the BTA-DVA COF suspension. After stirring at 130 °C for 10 h under an argon atmosphere, the mixture was washed with pure water and extracted with diethyl ether for 24 h using a Soxhlet extractor to ensure the removal of unreacted starting materials. The product was then dried under vacuum at 80 °C to obtain the final product. The obtained BTA-DVA-COOH COF was characterized by PXRD and IR, confirming the successful synthesis of BTA-DVA-COOH COF. SEM observation revealed that the synthesized BTA-DVA-COOH COF maintained a uniform nanosphere morphology.

[0042] Example 5: Synthesis scheme 5 for BTA-DVA-COOH COF material

[0043] Synthesis of BTA-DVA COF: 1,3,5-pyromellitic triamine and 2,5-divinyl p-ethylhexylene were loaded into a capped quartz tube with side tubes.

[0044] Benzodialdehyde was added in a molar ratio of 2:3. Subsequently, a mixture of o-dichlorobenzene, nBuOH, and 6M acetic acid was added in a volume ratio of 10:5:1. The mixture was sealed under anhydrous and oxygen-free conditions and allowed to stand at room temperature for 3 days. The precipitate was separated by filtration and then Soxhlet extracted for 24 hours using tetrahydrofuran (THF) as solvent to ensure the removal of unreacted raw materials and residual oligomers. The product BTA-DVA COF was obtained after drying in a vacuum oven at 80°C. Powder X-ray diffraction (PXRD) and infrared spectroscopy characterized the obtained BTA-DVA COF, confirming its successful synthesis. Scanning electron microscopy (SEM) revealed that the morphology of BTA-DVA COF consisted of uniform nanospheres.

[0045] Synthesis of BTA-DVA-COOH COF: 60 mg of the synthesized BTA-DVA COF powder was dissolved in 100 mL of n-methylpyrrolidone, and then ultrasonically pulverized for 30 min to obtain highly dispersed BTA-DVA COF. Subsequently, a mixture of 4-bromobenzoic acid (30 mg), Pd(OAc)₂ (3 mg), N,N-dimethyl-β-alanine hydrochloride (1 mg), and K₂CO₃ (140 mg) was added to the BTA-DVA-COF suspension. After stirring at 130 °C for 10 h under an argon atmosphere, the mixture was washed with pure water and extracted with diethyl ether for 24 h using a Soxhlet extractor to ensure the removal of unreacted starting materials. The product was then dried under vacuum at 80 °C to obtain the final product. The obtained BTA-DVA-COOH COF was characterized by PXRD and IR, confirming the successful synthesis of BTA-DVA-COOH COF. SEM observation revealed that the synthesized BTA-DVA-COOH COF maintained a uniform nanosphere morphology.

[0046] Example 6: Preparation of BTA-DVA COF and BTA-DVA-COOH COF coated probes

[0047] Preparation method of BTA-DVA COF-coated SPME probe: A stainless steel wire (4 cm long, 127 μm in diameter) was ultrasonically washed for 30 min each with deionized water, methanol, and acetone, and then dried in an 80℃ oven. A mixed slurry was prepared by adding 0.5 g of Dow Corning 184A component to 1.0 mL of cyclohexane and ultrasonically treated for 30 min to obtain a homogeneous slurry. Then, 0.05 g of Dow Corning 184B component was added. The wire was then immersed in the adhesive solution and rotated once in COF powder to obtain a single-layer coated probe. Subsequently, the fiber was heated in an 80℃ oven for 2 min to evaporate the cyclohexane. The above steps were repeated three times to obtain the homemade BTA-DVA COF-coated SPME probe, and its SEM image is shown below. Figure 8 As shown.

[0048] SPME probes with BTA-DVA-COOH COF coatings were prepared in the same manner, and their SEM images are shown below. Figure 9 As shown.

[0049] Example 7: Comparative Test of Solid-Phase Microextraction of Trihalomethanes Using Multiple Probes

[0050] Standard mixed solutions of CHCl3, CHBr2Cl, CHBr3, and CHI3 with concentrations of 10 μg·L⁻¹, 100 μg·L⁻¹, 1 mg·L⁻¹, and 10 mg·L⁻¹ were prepared using HPLC-grade methanol.

[0051] Dilute the standard solution with pure water to make working solutions of 10 ng·L⁻¹, 100 ng·L⁻¹, 1 μg·L⁻¹, 10 μg·L⁻¹ and 100 μg·L⁻¹.

[0052] Chromatographic parameter settings: Carrier gas: high-purity helium, constant flow mode, flow rate 1.2 mL / min. Splitless flow mode, column temperature program: 40℃ for 1 min, increase to 130℃ at 25℃ / min, hold for 2 min, increase to 280℃ at 100℃ / min, hold for 2 min.

[0053] Solid-phase microextraction parameters: extraction time: 40 min, extraction temperature: 40 ℃, elution time: 1 min, elution temperature: 250 ℃.

[0054] The MPS multi-functional autosampler manufactured by Gestel was coupled with an Agilent GCMS gas analyzer. Under the above conditions, a self-made carboxylated COF solid-phase microextraction probe was used to pre-treat four THMs (CHCl3, CHBr2Cl, CHBr3, and CHI3) in water. The probe was then directly inserted into the GC inlet for quantitative analysis.

[0055] The extraction effects of a self-made BTA-DVA SPME probe, a BTA-DVA-COOH SPME probe, and three commercial SPME probe combinations (PDMS, DVB, and PDMS / DVB / CAR) on four mixed aqueous solutions with a THM concentration of 10 ppb were compared. The results are as follows: Figure 10 As shown, the BTA-DVA-COOH SPME probe exhibits the best extraction performance, significantly outperforming the BTA-DVASPME probe, which in turn significantly outperforms the three commercial probe combinations.

[0056] Four THMs analytes were quantitatively detected using a self-made BTA-DVA-COOH SPME probe coupled with GC-MS. The linear range was as follows: Figure 11As shown, all values ​​are between 10 and 1000 ppt. Furthermore, the relative standard deviation of single-needle reproducibility is less than 5%, and the relative standard deviation of multi-needle reproducibility is also within 6%.

[0057] Example 8: Test of prednisolone adsorption by BTA-DVA-COOH COF probe

[0058] The prepared BTA-DVA-COOH-COF solid-phase microextraction probe was used for the quantitative detection of the glucocorticoid drug prednisolone. Prednisolone aqueous solutions with concentrations of 20 μg / L, 50 μg / L, 100 μg / L, 500 μg / L, 1 mg / L, and 5 mg / L were extracted in parallel using the self-made BTA-DVA-COOH-COF SPME probe, and the results were detected by LC-MS. The linear range was 20 μg / L to 5 mg / L. R0 2 =0.9997, detection limit is 5.4 μg / L, and quantitation limit is 17.7 μg / L. A mass spectrometry standard curve was plotted by taking the logarithm of the obtained mass spectrum peak area and the analyte concentration, as shown below. Figure 12 As shown in the figure. Using this standard curve as a reference, subsequent detections can use the signal values ​​obtained from mass spectrometry to infer the concentration of prednisolone in the actual sample.

[0059] Example 9: Comparative Test of Prednisolone by Solid-Phase Microextraction Using Multiple Probes

[0060] The extraction effects of a self-made BTA-DVA-COOH SPME probe and three combinations of commercial SPME probes (CAR / PDMS / DVB, PDMS / DVB, and PDMS) on four mixed aqueous solutions of prednisolone with a concentration of 10 ppb were compared. The results are as follows: Figure 13 As shown, under the same conditions, comparing the relative extraction amounts of each group, the BTA-DVA-COOH SPME probe showed the best extraction effect, which was significantly better than the combination of three commercial probes.

[0061] Obviously, the above embodiments of the present invention are merely examples to clearly illustrate the technical solutions of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. The application of a solid-phase microextraction probe material in the preparation of reagents or materials for detecting trihalomethanes and glucocorticoids, characterized in that, This includes a carboxyl-functionalized covalent organic framework, wherein the amino ligand of the carboxyl-functionalized covalent organic framework is 1,3,5-pyromellitic triamine, and the aldehyde ligand is 2,5-divinyl-terephthalaldehyde. The amino ligand and the aldehyde ligand undergo a covalent reaction, and the framework contains a carboxyl functional group. The monomeric chemical formula of the carboxyl-functionalized covalent organic framework is […]. 。 2. The application according to claim 1, characterized in that, The carboxyl functional group is provided by 4-bromobenzoic acid.

3. The application according to claim 1, characterized in that, The preparation method of the carboxyl-functionalized covalent organic framework includes the following steps: Step S1: Mix 1,3,5-pyromellitic triamine and 2,5-divinyl terephthalaldehyde, and add a mixture of o-dichlorobenzene, nBuOH and acetic acid. After sealing and standing, take the precipitate, extract it with tetrahydrofuran and dry it to obtain a vinyl-containing covalent organic framework. Step S2: Dissolve the vinyl-containing covalent organic framework in n-methylpyrrolidone to obtain a suspension. Add a mixture of 4-bromobenzoic acid, Pd(OAc)2, N,N-dimethyl-β-alanine hydrochloride, and K2CO3 to the suspension. Wash, extract, and dry to obtain the carboxyl-functionalized covalent organic framework.

4. The application according to claim 3, characterized in that, The molar ratio of 1,3,5-pyromellitic triamine and 2,5-divinyl terephthalaldehyde in step S1 is (1~2.5):3, and the volume ratio of o-dichlorobenzene, nBuOH and acetic acid is (3~10):(3~10):

1.

5. The application according to claim 3, characterized in that, The mass ratio of 4-bromobenzoic acid, Pd(OAc)2, N,N-dimethyl-β-alanine hydrochloride, and K2CO3 in step S2 is (30~80):(1~3):1:(100~150).

6. The application according to claim 1, wherein the glucocorticoid comprises prednisolone.

7. The application of the solid-phase microextraction probe material according to claim 1 in the preparation of solid-phase microextraction probe coatings.

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