A method for preparing a functionalized vinyl covalent organic polymer and applications thereof

Abstract

This invention discloses a method for preparing functionalized vinyl covalent organic polymers and their applications. The preparation method includes dissolving monomers DVA, TAPT, and azobisisobutyronitrile in methanol and reacting them at room temperature to obtain spherical nanoscale covalent organic polymers TAPT-DVA-COP. Sulfonic acid functionalized covalent organic polymers COP-SO3H and β-cyclodextrin functionalized covalent organic polymers COP-CD are obtained by modifying the polymers with sulfonic acid compounds and cyclodextrins, respectively. The vinyl covalent organic polymers synthesized using DVA and TAPT as monomers contain a large number of vinyl groups. The introduction of sulfonic acid groups or β-cyclodextrins onto these polymers results in O-H…O hydrogen bonds, LP…π interactions, CH…π interactions, and π…π interactions, exhibiting good chromatographic separation performance. When used as a solid-phase separation material in CEC, it can achieve selective separation of various organic compounds.

Description

Technical Field

[0001] This invention relates to the field of new materials, and in particular to a method for preparing a functionalized vinyl covalent organic polymer, and also to the application of the functionalized vinyl covalent organic polymer prepared by the method. Background Technology

[0002] Capillary electrochromatography (CEC) is a highly efficient chromatographic separation technique that combines the advantages of high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). The development of stationary phases in capillary columns has significantly influenced the development of CEC. Among packed columns, open tubular columns, and monolithic columns, organic polymer monolithic columns have attracted attention due to their high permeability, rapid mass transfer, ease of manufacture, and good stability over a wide pH range. However, the small surface area and limited number of interaction sites of organic monolithic columns lead to poor selective separation, making it difficult to meet the analytical requirements of complex and diverse samples. Therefore, the design and synthesis of novel stationary phases and the exploration of their separation mechanisms remain important tasks in the field of chromatography.

[0003] Covalent organic polymers (COPs) are composed of covalently bonded light atoms such as H, B, C, N, and O, exhibiting excellent thermal and chemical stability, as well as variable morphology and functionalization. Covalent organic frameworks (COFs) are a subclass of covalent organic polymers, possessing crystalline and periodic structures; however, their synthesis is complex due to limited monomers and demanding reaction conditions. Compared to COFs, amorphous COPs are easier to synthesize while retaining similar properties, such as larger specific surface area, abundant porosity, tunable pore size, and good thermal stability. To date, COPs have been studied in various scientific fields, including gas adsorption and storage, catalysis, and separation, and possess key applications and promising development prospects.

[0004] COPs (Cellular Organic Parabolic Columns) possess ordered structures, low density, and good stability. They can provide various interactions, including hydrophobicity, π-π bonding, hydrogen bonding, and ion exchange, and are easily functionalized, making them an ideal chromatographic stationary phase. Therefore, designing nanosphere-shaped COPs with multiple interaction sites is of great significance for improving the selective separation efficiency and the number of samples separated by monolithic organic columns. This addresses the shortcomings of existing monolithic organic columns, such as poor selective separation performance, which makes it difficult to meet the analytical requirements of complex and diverse samples. Summary of the Invention

[0005] In view of this, the first objective of the present invention is to provide a method for preparing functionalized vinyl covalent organic polymers, wherein the post-modified COPs obtained by the preparation method are uniform in size and have multiple interaction sites such as OH…O hydrogen bonds, LP…π interactions, CH…π interactions and π…π interactions, and can also provide hydrophobic effects, effectively improving the separation effect of the capillary monolithic column.

[0006] The second objective of this invention is to provide the application of the prepared functionalized vinyl covalent organic polymer as the stationary phase of a capillary monolithic column, which is suitable for the separation and analysis of various analytes with different physicochemical properties and has important guiding significance.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The preparation method of the functionalized vinyl covalent organic polymer of the present invention involves first synthesizing the vinyl covalent organic polymer, and then performing functionalization modification on it, specifically including the following:

[0009] In the first step, monomers 2,5-divinyl-1,4-benzaldehyde (DVA) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) were mixed with an organic solvent in a molar ratio of 1:1 to 4:3, and a catalyst was added. The mixture was reacted at room temperature for 24 to 96 hours. After the reaction was completed, the precipitate was obtained by centrifugation or filtration, washed, and dried to obtain the vinyl covalent organic polymer TAPT-DVA-COP.

[0010] The second step involves mixing TAPT-DVA-COP, the modifying agent, and azobisisobutyronitrile in anhydrous ethanol, sonicating to obtain a suspension, and then placing the suspension in a nitrogen environment for stirring and reaction. After the reaction is complete, the precipitate is obtained by centrifugation or filtration, washed, and dried to obtain the functionalized vinyl covalent organic polymer.

[0011] The modifying agent is a sulfonic acid compound or a cyclodextrin, wherein the sulfonic acid compound is 1,2-ethanedisulfonic acid; and the cyclodextrin is 6-mercapto-6-deoxy-β-cyclodextrin.

[0012] In this invention, when TAPT-DVA-COP prepared in this invention is post-modified with 1,2-ethanedisulfonic acid as a modifier, a sulfonic acid-functionalized vinyl covalent organic polymer is obtained; when TAPT-DVA-COP is post-modified with 6-mercapto-6-deoxy-β-cyclodextrin as a modifier, a cyclodextrin-functionalized vinyl covalent organic polymer is obtained.

[0013] In this invention, the washing in the first step is to wash with anhydrous ethanol, tetrahydrofuran and acetone 2 to 5 times in sequence; the washing in the second step is to wash with acetone and anhydrous ethanol alternately 2 to 5 times in sequence; the drying conditions in the first and second steps are the same, both are drying under vacuum, drying temperature 50 to 80°C, and drying time ≥24h.

[0014] In this invention, the organic solvent in the first step is methanol, acetonitrile, or ethylene glycol. For a monolithic capillary column, spherical COPs used as the stationary phase for direct packing ensure good permeability and column efficiency, while the solvent system during COPs polymerization is a key factor affecting its formation. To ensure uniform spherical COPs, methanol is preferably used as the organic solvent in the first step of this invention.

[0015] In this invention, in the second step, the mass ratio of TAPT-DVA-COP, cyclodextrin, and azobisisobutyronitrile (AIBN) is (30-50):(150-250):(1-5), that is, TAPT-DVA-COP is 30-50 mg, cyclodextrin is 150-250 mg, and AIBN is 1-5 mg; the mass ratio of TAPT-DVA-COP, sulfonic acid compound, and AIBN is (10-30):(30-90):(1-5), that is, TAPT-DVA-COP is 10-30 mg, sulfonic acid compound is 30-90 mg, and AIBN is 1-5 mg.

[0016] This invention also provides the application of the functionalized vinyl covalent organic polymer prepared by this invention as a stationary phase material for capillary monolithic columns in the selective separation of neutral small molecule compounds, charged small molecule compounds, isomers, acidic phenolic compounds, and chiral molecules; wherein the neutral small molecule compounds include monosubstituted benzenes, alkylbenzenes, and p-hydroxybenzoates.

[0017] More preferably, the sulfonic acid-functionalized vinyl covalent organic polymer and the cyclodextrin-functionalized vinyl covalent organic polymer prepared by the present invention can both be used for the selective separation of neutral small molecule compounds; the sulfonic acid-functionalized vinyl covalent organic polymer is also suitable for the selective separation of charged small molecule compounds, and the cyclodextrin-functionalized vinyl covalent organic polymer is also suitable for the selective separation of phenolic substances, isomers and the resolution of chiral molecules.

[0018] In this invention, monosubstituted benzenes mainly include benzoic acid, benzyl alcohol, benzaldehyde, anisole, chlorobenzene, bromobenzene, and iodobenzene; alkylbenzenes include toluene, ethylbenzene, propylbenzene, butylbenzene, and pentabenzene; and parabens include methylparaben, ethylparaben, propylparaben, and butylparaben.

[0019] In this invention, the acidic phenolic compounds include hydroquinone, p-methoxyphenol, phenol, and p-methylphenol.

[0020] In this invention, the charged small molecule compound includes nucleoside bases and biogenic amines. The nucleoside bases include uracil, cytosine, and 6-chloro-7-azapurine; the biogenic amines include tyramine, histamine, and tryptamine.

[0021] In this invention, the isomers include the selective separation of o-nitrophenol, m-nitrophenol, and p-nitrophenol; the chiral molecules include ractopamine, flavanones, propranolol, and binatol, which can achieve baseline separation of ractopamine.

[0022] This invention also provides a method for preparing a functionalized vinyl covalent organic polymer capillary monolithic column, which uses a sulfonic acid-functionalized vinyl covalent organic polymer or a cyclodextrin-functionalized vinyl covalent organic polymer as the stationary phase material, including the following:

[0023] S1, Silanization treatment of the inner wall surface of the capillary;

[0024] S2, add the functionalized vinyl covalent organic polymer to the polymerization solution, mix it by ultrasonication, inject the mixed prepolymer solution into the capillary in the first step, and polymerize it at 50-70°C for 10-20 h.

[0025] The polymerization solution uses glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) as monomers, n-propanol and 1,4-butanediol as porogens, AIBN as an initiator, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as an electroosmotic flow generator. The volume ratio of monomers to porogens is 1 / 9 to 4 / 6, the volume ratio of GMA to EDMA is 1:1, and the volume ratio of n-propanol to 1,4-butanediol is 1:1.

[0026] S3. After the reaction is complete, the capillary is rinsed with pure methanol mobile phase to remove unreacted polymerization solution, and then dried with nitrogen. The polyimide at the effective column end of the monolithic column is removed to create a detection window, resulting in a capillary monolithic column with functionalized vinyl covalent organic polymer as stationary phase.

[0027] For monolithic capillary columns, the monomer-to-porogen ratio in the polymerization solution, the polymerization temperature, and the incorporation of functionalized vinyl covalent organic polymers are key factors affecting the column's permeability and efficiency. This invention explores these factors to ensure optimal column permeability and efficiency. For sulfonic acid-functionalized vinyl covalent organic polymer (COP-SO3H) monolithic columns, considering both permeability and efficiency, a monomer-to-porogen volume ratio of 4 / 6 is optimal; the COP-SO3H addition amount is controlled at 20 mg / mL.-1 Within (preferably 15 mg / mL) -1 The preferred polymerization temperature is 50-60℃ (60℃ is optimal).

[0028] For monolithic columns made of cyclodextrin-functionalized vinyl covalent organic polymers (COP-CD), considering column permeability and efficiency, a monomer to porogen volume ratio of 3 / 7 is optimal; the amount of COP-CD added is preferably controlled at 20 mg / mL. -1 Within 15 mg / mL, the optimal value is 15 mg / mL. -1 The preferred polymerization temperature is 50-60℃, with 60℃ being the optimal polymerization temperature.

[0029] In this invention, when selectively analyzing neutral small molecule compounds, charged small molecule compounds, isomers, acidic phenolic compounds, and chiral molecules, CEC-UV is used for quantitative detection and analysis. The detection conditions for CEC-UV are as follows: using buffer and acetonitrile as the mobile phase, the operating voltage is -10 kV to -20 kV, and the wavelength is 210 nm to 220 nm. The volume fraction of acetonitrile in the mobile phase is 20% to 90%, and the pH of the buffer is 3.0 to 8.0.

[0030] For CEC-UV, the concentration, pH, and operating voltage of the buffer solution are key factors affecting its electroosmotic flow (EOF). The mobile phase of this invention is preferably a 5 mM NaH2PO4 buffer solution (pH 3.0–8.0) with varying proportions of acetonitrile, and the operating voltage is preferably -10 kV to -20 kV, more preferably -15 kV.

[0031] Compared with the prior art, the advantages of the present invention are reflected in the following aspects:

[0032] 1. This invention uses DVA and TAPT as monomers and methanol as solvent to obtain uniformly sized spherical COPs at room temperature. The reaction conditions are mild, the method is simple, and the operation is highly operable. The TAPT-DVA-COP synthesized by this invention has functionalizable vinyl groups, which lays the foundation for subsequent modification.

[0033] 2. This invention introduces sulfonic acid into the nanosphere covalent organic polymer TAPT-DVA-COP to obtain uniformly sized spherical COP-SO3H, laying the foundation for obtaining a monolithic COP-SO3H column with uniform structure and high mechanical stability. Furthermore, the introduction of sulfonic acid enables various interactions within the COP-SO3H of this invention. Taking COP-SO3H and monosubstituted benzene as examples, the benzene ring of COP-SO3H interacts with the benzene ring structure of the analytes (benzyl alcohol and benzaldehyde) via π…π interactions. The sulfonic acid group of COP-SO3H also exhibits OH…O hydrogen bonding with the analytes (benzoic acid, benzyl alcohol, and benzaldehyde). The lone pair electrons of oxygen in the substituents of the analytes (anisole and benzaldehyde) can approach the conjugated system of COP-SO3H, forming LP…π interactions. The carbon chain in COP-SO3H interacts with the benzene ring in the structure of the analytes (benzoic acid and anisole) via CH…π interactions. These interactions (π…π interactions, hydrogen bonding, LP…π interactions, and CH…π interactions) enable the COP-SO3H monolithic column of this invention to exhibit good separation performance.

[0034] This invention employs a physical doping method to prepare a monolithic COP-SO3H column. Through reasonable optimization of polymerization temperature, the ratio of porogen to monomer, and the amount of COP-SO3H incorporated, a monolithic COP-SO3H column with good permeability and column efficiency was ultimately obtained. The monolithic COP-SO3H column of this invention exhibits a uniform and continuous three-dimensional porous structure, possessing not only high sensitivity but also a low detection limit, as well as good repeatability and stability. Experiments have shown that the monolithic COP-SO3H column of this invention not only possesses a reversed-phase chromatography separation mechanism but also a weak cation exchange chromatography separation mechanism. This allows the monolithic column to be used not only for the separation of monosubstituted benzenes but also for the separation of alkylbenzenes, p-hydroxybenzoates, nucleoside bases, biogenic amines, and other substances, making it suitable for a wide range of separation targets and providing important guidance for analytical techniques.

[0035] 3. β-Cyclodextrins (β-CDs) and their derivatives are cyclic oligosaccharides that can act as chiral selectors. They possess hydrophobic cavities that can accommodate guest molecules and hydroxyl-rich cyclic structures, allowing them to form inclusion complexes with different analytes, enhancing hydrogen bonding with the target analyte and providing possibilities for modification with other functional groups. Therefore, they are widely used in chiral separation and small molecule separation. However, to date, there are few reports on the use of β-CDs combined with COPs as stationary phases.

[0036] This invention synthesizes nanosphere-shaped covalent organic polymer TAPT-DVA-COP using DVA and TAPT as monomers. β-cyclodextrin is introduced onto TAPT-DVA-COP via click chemistry to obtain uniformly sized spherical COP-CDs, laying the foundation for obtaining a monolithic COP-CD column with uniform structure and high mechanical stability. The introduction of β-cyclodextrin leads to various interactions between COP-CD and analytes, including OH…O hydrogen bonding, LP…π interactions, CH…π interactions, and π…π interactions. For example, hydrogen bonding exists between the cyclodextrin in COP-CD and all analytes; LP…π interactions exist between the lone pair electrons of the β-cyclodextrin hydroxyl oxygen and the benzene ring in the analyte; CH…π interactions exist between the carbon chain and the benzene ring in the analyte structure; and π…π interactions exist between the benzene ring in the analyte and the conjugated system of COP-CD. These interactions ensure the separation performance of the monolithic COP-CD column.

[0037] This invention employs a physical doping method to prepare a COP-CD monolithic capillary column with a reversed-phase chromatography separation mechanism. Through reasonable optimization of polymerization temperature, the ratio of porogen to monomer, and the amount of COP-CD incorporated, a COP-CD monolithic column with good permeability and column efficiency was ultimately obtained. Experiments show that the COP-CD monolithic column of this invention can not only be used for the selective separation and quantitative analysis of neutral small molecules, but also for the selective separation of isomers and chiral molecules. It exhibits high sensitivity, low detection limit, and good repeatability and stability, making it suitable for the quantitative detection and analysis of real samples, and thus of significant importance. Attached Figure Description

[0038] Figure 1 This is a flowchart of the preparation process of COP-SO3H in this invention.

[0039] Figure 2 These are the SEM and TEM-EDS images of TAPT-DVA-COP and COP-SO3H in this invention.

[0040] Figure 2 In the image, (a) is a SEM image of TAPT-DVA-COP; (b) is a SEM image of COP-SO3H; (c) is a TEM image of TAPT-DVA-COP; (d) is a SEM image of COP-SO3H; and (e)-(h) are EDS images of COP-SO3H.

[0041] Figure 3 The FT-IR and solid-state of TAPT-DVA-COP and COP-SO3H in this invention are 13 C NMR spectrum and TGA curve.

[0042] Figure 3In the figure, (a) is the FT-IR spectrum of the monomer, TAPT-DVA-COP, and COP-SO3H; (b) is the solid-state spectrum of TAPT-DVA-COP and COP-SO3H. 13 (c) is the nuclear magnetic resonance spectrum; (c) is the TGA curve of TAPT-DVA-COP and COP-SO3H.

[0043] Figure 4 XPS characterization of TAPT-DVA-COP and COP-SO3H.

[0044] Figure 4 In the image, (a) is the high-resolution full spectrum of TAPT-DVA-COP and COP-SO3H; (b) is the high-resolution C 1s spectrum of TAPT-DVA-COP and COP-SO3H; and (c) is the high-resolution S 2p spectrum of TAPT-DVA-COP and COP-SO3H.

[0045] Figure 5 These are contact angle characterization diagrams for TAPT-DVA-COP and COP-SO3H. Figure 5 In the figures, (a) is the contact angle of TAPT-DVA-COP; (b) is the contact angle of COP-SO3H; and (c) is the contact angle of COP-CD.

[0046] Figure 6 This is a flowchart illustrating the preparation process of the cyclodextrin-functionalized vinyl covalent organic polymer COP-CD in this invention.

[0047] Figure 7 These are SEM images of TAPT-DVA-COP and COP-CD in this invention. Figure 7 In the diagram, (ac) is the SEM image of TAPT-DVA-COP; (df) is the SEM image of COP-CD.

[0048] Figure 8 These are SEM and TEM-EDS images of TAPT-DVA-COP and COP-CD.

[0049] Figure 8 In the image, (a) is the SEM image of TAPT-DVA-COP; (b) is the SEM image of COP-CD; (c) is the TEM image of TAPT-DVA-COP; (d) is the SEM image of COP-CD; and (e)-(h) are the EDS images of COP-CD.

[0050] Figure 9 The FT-IR and solid-state of TAPT-DVA-COP and COP-CD in this invention 13 C NMR spectrum.

[0051] Figure 9 (a) shows the FT-IR spectra of the modifier, TAPT-DVA-COP, and COP-CD; (b) shows the solid-state spectra of TAPT-DVA-COP and COP-CD. 13 C10 NMR spectrum.

[0052] Figure 10 These are the TGA curves and X-ray diffraction characterization diagrams of TAPT-DVA-COP and COP-CD in this invention.

[0053] Figure 10 (a) shows the TGA curves of TAPT-DVA-COP and COP-CD; (b) shows the X-ray diffraction characterization of TAPT-DVA-COP and COP-CD.

[0054] Figure 11 These are XPS characterization diagrams of TAPT-DVA-COP and COP-CD in this invention.

[0055] Figure 11 In the image, (a) is the high-resolution full spectrum of TAPT-DVA-COP and COP-CD; (b) is the high-resolution C 1s spectrum of TAPT-DVA-COP and COP-CD; and (c) is the high-resolution S 2p spectrum of TAPT-DVA-COP and COP-CD.

[0056] Figure 12 This is a SEM image of the monolithic column prepared according to the present invention.

[0057] Figure 12 In the figure, (a) is the SEM image of the TAPT-DVA-COP monolithic column; (b) is the SEM image of the COP-SO3H monolithic column; and (c) is the SEM image of the COP-CD monolithic column.

[0058] Figure 13 This is the FT-IR image of the monolithic column prepared according to the present invention.

[0059] Figure 14 This is a characterization diagram of nitrogen adsorption of the monolithic column prepared in this invention.

[0060] Figure 14 In the figures, (a) is the N2 adsorption-desorption isotherm curve and pore size distribution curve of the blank monolithic column; (b) is the N2 adsorption-desorption isotherm curve and pore size distribution curve of the COP-SO3H monolithic column; (c) is the N2 adsorption-desorption isotherm curve and pore size distribution curve of the TAPT-DVA-COP monolithic column; and (d) is the N2 adsorption-desorption isotherm curve and pore size distribution curve of the COP-CD monolithic column.

[0061] Figure 15This is a selective separation diagram of monosubstituted benzenes using the TAPT-DVA-COP monolithic column and the COP-SO3H monolithic column in Example 6 of this invention. In the diagram, peaks 1-7 correspond to benzoic acid, benzyl alcohol, benzaldehyde, anisole, chlorobenzene, bromobenzene, and iodobenzene, respectively.

[0062] Figure 16 This is the reproducible separation spectrum of monosubstituted benzene using the COP-SO3H monolithic column in Example 6 of this invention.

[0063] Figure 16 In the diagram, (a) is the needle-to-needle separation spectrum of the monolithic COP-SO3H column (n=10), (b) is the inter-needle separation spectrum (n=5), (d) is the inter-column separation spectrum (n=3), and (c) is the effect of the mobile phase flow rate on the back pressure of the monolithic COP-SO3H column.

[0064] Figure 17 This is a diagram illustrating the non-covalent interactions between COP-SO3H and the analyte. Figure 17 In the given list, (a) is benzoic acid; (b) is benzyl alcohol; (c) is anisole; and (d) is benzaldehyde.

[0065] Figure 18 This is the selective separation spectrum of charged small molecules in Example 6. Figure 18 In the figure, (a) is the relationship between buffer pH and analyte log k; (b) is the selective separation of nucleoside bases by the TAPT-DVA-COP monolithic column and the COP-SO3H monolithic column, with chromatographic peaks 1-3 being uracil, cytosine, and 6-chloro-7-azapurine, respectively; (c) is the selective separation of biogenic amines by the TAPT-DVA-COP monolithic column and the COP-SO3H monolithic column, with chromatographic peaks 1-3 being tyramine, histamine, and tryptamine, respectively.

[0066] Figure 19 This is the separation spectrum of p-hydroxybenzoic acid ester in Example 7. Figure 19 In the figure, (a) is the selective separation chromatogram of parabens by the TAPT-DVA-COP monolithic column and the COP-SO3H monolithic column; (b) is the selective separation chromatogram of parabens by the COP-SO3H monolithic column in the actual sample and the spiked sample. In (a) and (b), chromatographic peaks 1-4 are parabens, ethylparaben, propylparaben and butylparaben, respectively.

[0067] Figure 20 This is the separation spectrum and separation mechanism of Example 8. Figure 20In the figure, (a) is the separation mechanism diagram of the COP-SO3H monolithic column and the relationship between different acetonitrile contents and alkylbenzene log k; (b) is the selective separation diagram of alkylbenzene by the TAPT-DVA-COP monolithic column and the COP-SO3H monolithic column, in which chromatographic peaks 1-5 are toluene, ethylbenzene, propylbenzene, butadiene and pentobenzene, respectively; (c) is the selective separation diagram of alkylbenzene in the actual sample and alkylbenzene in the spiked sample by the COP-SO3H monolithic column, in which chromatographic peaks 1-5 are toluene, ethylbenzene, propylbenzene, butadiene and pentobenzene, respectively.

[0068] Figure 21 This is the selective separation spectrum and separation mechanism of alkylbenzenes by the COP-CD monolithic column in Example 9.

[0069] exist Figure 21 In the figure, (a) is a graph showing the relationship between different acetonitrile contents and alkylbenzene log k; in (b), chromatographic peaks 1-5 are toluene, ethylbenzene, propylbenzene, butadiene, and pentobenzene, respectively.

[0070] Figure 22 This is a repeat separation chromatogram of alkylbenzenes separated by a COP-CD monolithic column in Example 9. In the figure, (a) is the inter-column separation (n=10); (b) is the inter-column separation (n=5); (d) is the inter-column separation (n=3); and (c) shows the effect of mobile phase flow rate on the back pressure of the COP-CD monolithic column. Furthermore, peaks 1-5 in (a), (b), and (d) are, in order, toluene, ethylbenzene, propylbenzene, butadiene, and pentabenzene.

[0071] Figure 23 This is a selective separation diagram of monosubstituted benzenes using the TAPT-DVA-COP monolithic column and the COP-CD monolithic column in Example 10. In the diagram, (a) is a known sample, with chromatographic peaks 1-7 being benzoic acid, benzyl alcohol, benzaldehyde, anisole, chlorobenzene, bromobenzene, and iodobenzene, respectively; (b) is the actual sample and the spiked sample, with chromatographic peaks 1-4 being toluene, chlorobenzene, bromobenzene, and iodobenzene, respectively.

[0072] Figure 24 This is a selective resolution diagram of phenolic substances and isomers using the TAPT-DVA-COP monolithic column and COP-CD monolithic column of the present invention. Figure 24 In (a), chromatographic peaks 1-4 are, in order, hydroquinone, p-methoxyphenol, phenol, and p-methylphenol; in (b), chromatographic peaks 1-3 are, in order, p-nitrophenol, m-nitrophenol, and o-nitrophenol.

[0073] Figure 25 This is a diagram illustrating the non-covalent interactions between the COP-CD monolithic column and the analyte. Figure 25 In the list, (a) is hydroquinone; (b) is p-methoxyphenol; (c) is phenol; and (d) is p-methylphenol.

[0074] Figure 26 This is a diagram showing the separation of chiral molecules using the TAPT-DVA-COP monolithic column and the COP-CD monolithic column in Embodiment 13 of the present invention. Figure 26 In the above, (a) is ractopamine; (b) is flavanone; (c) is propranolol; and (d) is binaphthol. Detailed implementation methods.

[0075] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0076] I. Material Preparation and Characterization

[0077] Example 1: Preparation of sulfonic acid-functionalized vinyl covalent organic polymer – COP-SO3H

[0078] 1. This invention synthesizes COPs using 2,5-divinyl-1,4-benzaldehyde (DVA) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) as monomers, and then modifies the synthesized COPs with sulfonic acid to obtain the sulfonic acid-functionalized vinyl covalent organic polymer COP-SO3H (synthetic route see...). Figure 1 Specifically, it includes the following:

[0079] Step 1: Three portions of 2,5-divinyl-1,4-phenylenedialdehyde (DVA, 11.16 mg, 0.3 mM) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT, 14.16 mg, 0.2 mM) were weighed and dissolved in 5 mL of methanol. The mixture was sonicated for 5 min. After sonication, 0.4 mL of glacial acetic acid (12 M) was slowly added dropwise to the mixture, and the reaction was carried out at room temperature for 72 h. After the reaction was completed, the yellow precipitate was collected by centrifugation and washed three times each with anhydrous ethanol, tetrahydrofuran, and acetone. The precipitate was dried under vacuum at 60 °C for 24 h to obtain the vinyl covalent organic polymer, hereinafter referred to as TAPT-DVA-COP, with the following structural formula:

[0080] ;

[0081] In the second step, TAPT-DVA-COP (20 mg), 1,2-ethanedisulfonic acid (60 mg), and azobisisobutyronitrile (AIBN, 2 mg) obtained in step 1 were dissolved in 60 mL of anhydrous ethanol under nitrogen protection and stirred at 80 °C for 48 h. The product was washed three times alternately with acetone and anhydrous ethanol and dried under vacuum at 60 °C for 24 h to obtain a brown solid powder of sulfonic acid-functionalized vinyl covalent organic polymer, hereinafter referred to as COP-SO3H, with the following structural formula:

[0082]

[0083] 2. Characterization of sulfonic acid-functionalized vinyl covalent organic polymer COP-SO3H

[0084] 1) For monolithic columns, directly filling irregularly shaped or small-sized COPs as the stationary phase may lead to high back pressure and low column efficiency. This invention investigated the effect of solvent on the morphology of TAPT-DVA-COP. The results showed that when methanol was used as the solvent, TAPT-DVA-COP had a spherical structure. After modification with sulfonic acid, the surface of COP-SO3H was roughened, forming more uniform particles without destroying the main morphology of TAPT-DVA-COP, which still maintained a regular spherical structure. See details below. Figure 2 (a) and 2(b).

[0085] 2) The TEM-EDS results of TAPT-DVA-COP and COP-SO3H are shown in [reference needed]. Figure 2 (c)-(h). By Figure 2 (c)-(d) show that both TAPT-DVA-COP and COP-SO3H are spherical structures. Figure 2 (e)-(h) show that C, N, O and S elements are uniformly distributed on the surface of COP-SO3H spheres, and the sulfur content of COP-SO3H is 7.44%.

[0086] 3) The FT-IR characterization results of COP-SO3H are shown in [reference needed]. Figure 4 (a). By Figure 4 (a) It can be seen that TAPT-DVA-COP is at 1604 cm. -1 There is a typical C=N stretching vibration absorption peak at this location, indicating the successful formation of the imine bond; the C=O stretching vibration absorption peak in DVA (1680 cm⁻¹) -1 ) and the NH stretching vibration absorption peak in TAPT (3300-3400 cm⁻¹) -1 The disappearance of ) also indicates the formation of imine bonds. Compared with TAPT-DVA-COP, COP-SO3H at 555 cm⁻¹ -1 A new CS stretching vibration absorption peak was observed, confirming the successful modification of 1,2-ethanedisulfonic acid on TAPT-DVA-COP.

[0087] 4) Solids of TAPT-DVA-COP and COP-SO3H 13 The C nuclear magnetic resonance spectrum is shown in [the image]. Figure 4 (b). By Figure 4(b) It can be seen that the characteristic peak of the C=C bond at 123 ppm of COP-SO3H disappears, and two new characteristic peaks appear at 47.3 and 79.1 ppm, which are attributed to the formation of C=C and CO chemical bonds, respectively. Solids of TAPT-DVA-COP and COP-SO3H 13 The results of C14 nuclear magnetic resonance characterization further confirmed the successful preparation of TAPT-DVA-COP and COP-SO3H.

[0088] 5) The TGA curves of TAPT-DVA-COP and COP-SO3H are shown below. Figure 5 .Depend on Figure 5 It can be seen that the weight loss of TAPT-DVA-COP and COP-SO3H is negligible in the temperature range of 50-300℃, which is related to the evaporation of free water and water adsorbed in the molecular space of the material. Significant weight loss begins to appear from 300℃, mainly due to polymer decomposition. The results indicate that TAPT-DVA-COP and COP-SO3H synthesized by this method exhibit good thermal stability between 50-300℃.

[0089] 6) XPS characterization results of TAPT-DVA-COP and COP-SO3H are shown in [reference needed]. Figure 6 .Depend on Figure 6 It can be seen that in the high-resolution XPS C 1s spectrum of COP-SO3H, the characteristic peaks at 284.9 and 288.9 eV are attributed to CC and C=N bonds, respectively, and the binding energy at 286.2 eV is related to the CO bond. The high-resolution XPS spectrum of S 2p of COP-SO3H shows two characteristic peaks: the characteristic peak with a binding energy of 166.9 eV is related to the SO bond, and the characteristic peak with a binding energy of 164.5 eV is related to the CS bond. The results indicate that 1,2-ethanedisulfonic acid was successfully modified onto TAPT-DVA-COP via CO covalent bonds.

[0090] 7) The contact angles of TAPT-DVA-COP and COP-SO3H are shown in [reference needed]. Figure 5 .Depend on Figure 5 As shown in (a) and (b), the contact angle of TAPT-DVA-COP is greater than 92°, while the contact angle of COP-SO3H modified with sulfonic acid group is 44°, indicating that the hydrophilicity of COP-SO3H is enhanced.

[0091] Example 2: Preparation and characterization of the cyclodextrin-functionalized vinyl covalent organic polymer of the present invention.

[0092] 1. Preparation method of cyclodextrin-functionalized vinyl covalent organic polymers (synthetic route see...) Figure 6 ), including the following:

[0093] The first step is the same as the first step in Example 1;

[0094] In the second step, the TAPT-DVA-COP (35 mg), AIBN (2 mg), and 6-mercapto-6-deoxy-β-cyclodextrin (175 mg) obtained in step 1 were dissolved in 60 mL of anhydrous methanol and sonicated for 10 min to obtain a suspension. The suspension was stirred at 80 °C for 48 h under nitrogen atmosphere. After centrifugation, the precipitate was washed three times each with DMF, anhydrous methanol, deionized water, and acetone. The precipitate was then vacuum dried at 60 °C for 24 h to obtain a pale yellow solid powder—COP-CD, whose structural formula is as follows:

[0095]

[0096] 2. Characterization of cyclodextrin-functionalized vinyl covalent organic polymer COP-CD

[0097] 1) SEM characterization of COP-CD is shown in [reference needed]. Figure 7 .Depend on Figure 7 It can be seen that TAPT-DVA-COP is spherical. The modification of cyclodextrin roughens the surface of COP-CD, but does not destroy the main morphology of TAPT-DVA-COP, and still maintains a regular spherical structure, indicating that the post-modification of cyclodextrin has a certain degree of stability.

[0098] 2) The TEM-EDS characterization results of COP-CD are shown in [the table below]. Figure 8 .Depend on Figure 8 It can be seen that both TAPT-DVA-COP and COP-CD are spherical, and C, N, O, and S elements are uniformly distributed on the surface of the COP-CD spheres. Furthermore, EDS analysis showed that the sulfur content in COP-CD was 6.53%, indicating that cyclodextrin was successfully bonded to the polymer surface.

[0099] 3) The FT-IR characterization results of COP-CD are shown in [reference needed]. Figure 9 (a). By Figure 9 (a) It can be seen that TAPT-DVA-COP is at 1604 cm. -1 There is a typical C=N stretching vibration absorption peak at 1604 cm⁻¹, indicating the successful formation of the imine bond; COP-CD not only at 1604 cm⁻¹ -1 It exhibits a typical C=N stretching vibration absorption peak, and is also at 1071 cm⁻¹. -1 It exhibits an absorption peak for the stretching vibration of COC at 2575 cm⁻¹. -1 The SH stretching vibration absorption peak disappeared at the location. This indicates that cyclodextrin was successfully bonded to the TAPT-DVA-COP framework.

[0100] 4) Solid-state TAPT-DVA-COP and COP-CD13 The C nuclear magnetic resonance spectrum is shown in [the image]. Figure 9 (b). By Figure 9 (b) It can be seen that in COP-CD 13 In the C NMR spectrum, the absorption peak of the C=C bond disappears at 114.1 ppm; and absorption peaks of the C=C and CO bonds appear at 60.7 and 73.7 ppm, indicating the successful preparation of COP-CD.

[0101] 5) The TGA curves for TAPT-DVA-COP and COP-CD are shown below. Figure 10 (a) The weight loss is negligible between 50 and 200 °C; the decomposition of COP-CD begins at 200 °C and ends at around 700 °C. The results indicate that the COP-CD of this invention exhibits good thermal and chemical stability between 50 and 200 °C.

[0102] 6) The XRD characterization results of TAPT-DVA-COP and COP-CD are shown in [reference needed]. Figure 10 (b). By Figure 10 (b) It can be seen that TAPT-DVA-COP exhibits amorphous characteristics, and the COP-CD obtained after cyclodextrin modification shows cyclodextrin characteristic peaks, indicating that the cyclodextrin group was successfully modified on TAPT-DVA-COP.

[0103] 7) XPS characterization results of TAPT-DVA-COP and COP-CD are shown in [reference needed]. Figure 11 .Depend on Figure 11 It can be seen that in the high-resolution XPS C 1s spectrum of COP-CD, the binding energies of 284.4 eV and 288.1 eV are attributed to the CC and C=N bonds, respectively; the binding energy of 286.0 eV is related to the CO bond; the high-resolution XPS spectrum of S 2p shows a characteristic peak, which is related to the CS bond with a binding energy of 163.4 eV. The results indicate that β-CD was successfully modified onto TAPT-DVA-COP via CS covalent bonds.

[0104] 8) The contact angles of TAPT-DVA-COP and COP-CD are shown in [reference needed]. Figure 5 (a) and (c). By Figure 5 As shown in (a) and (c), the contact angle of TAPT-DVA-COP is greater than 90°, indicating that it is hydrophobic; the contact angle of COP-CD modified with cyclodextrin decreases from 93° to 45°, indicating that the contact angle of COP-CD modified with cyclodextrin is that of a hydrophilic material.

[0105] II. Preparation of COP-SO3H Monolithic Columns, COP-CD Monolithic Columns, and TAPT-DVA-COP Monolithic Columns

[0106] 1. Example 3: Preparation of a monolithic COP-SO3H column

[0107] First, the fused silica capillary was rinsed sequentially with 1M NaOH for 3 h, deionized water for 40 min, 1M HCl for 3 h, deionized water for 40 min, and methanol for 40 min; then dried under a nitrogen flow for 1 h; MPS / methanol solution (50 / 50, v / v) was injected into the dried capillary, and after 40 min, both ends of the column were plugged and placed in a water bath at 40°C for 12 h.

[0108] The second step involves preparing a polymerization solution using GMA and EDMA as monomers (volume ratio 1:1), n-propanol and 1,4-butanediol (volume ratio 1:1) as porogens, 1.5 mg AIBN as an initiator, and 1.0 mg AMPS as an electroosmotic flow generator.

[0109] The polymerization solution was added to COP-SO3H to obtain mixed solutions with different doping amounts (the doping amount of COP-SO3H was controlled between 5 and 20 mg / mL). -1 After the mixture is ultrasonically dispersed evenly, it is injected into the pretreated capillary to carry out the polymerization reaction.

[0110] The third step involves rinsing the column with pure methanol mobile phase for 12 h to remove unreacted polymer solution, followed by drying with nitrogen. The outer layer (polyimide) at the effective end of the monolithic column is burned off to create a detection window (approximately 3 mm), thus preparing a COP-SO3H monolithic column with a total length of 60 cm and an effective length of 25 cm.

[0111] Polymerization temperature, monomer / porogen ratio, and doping concentration are all key factors affecting the permeability and efficiency of the monolithic column. To ensure good permeability and efficiency of the COP-SO3H monolithic column, the preferred volume ratio of monomer to porogen is 4 / 6, and the volume ratio of 1,4-butanediol, n-propanol, GMA, and EDMA is 3:3:2:2. The polymerization temperature is preferably controlled between 50℃ and 70℃ (more preferably 60℃), and the COP-SO3H doping concentration is controlled at 20 mg / mL. -1 Within (in this example, 15 mg / mL) -1 ).

[0112] 2. Example 4: Preparation of a monolithic COP-CD column

[0113] The first step in preparing the monolithic COP-CD column in this invention is the same as in Example 3. The difference lies in the second step. In this example, the volume ratio of monomer to porogen is preferably 1 / 9 to 3 / 7 (3 / 7 in this example), and the volume ratio of 1,4-butanediol, n-propanol, GMA, and EDMA is 7:7:3:3. The polymerization temperature is preferably controlled between 50°C and 60°C (60°C in this example), and the COP-CD doping amount is controlled at 20 mg / mL. -1 Within (in this example, 15 mg / mL) -1 ).

[0114] 3. Comparative Example 1: Preparation of TAPT-DVA-COP monolithic column and blank column

[0115] The preparation method of the TAPT-DVA-COP monolithic column in this invention is the same as in Example 3.

[0116] In this invention, a blank monolithic column is obtained by directly polymerizing an undoped polymerization solution (i.e., without the addition of TAPT-DVA-COP) in a silanized capillary.

[0117] 4. Characterization of the prepared COP-SO3H monolithic column, COP-CD monolithic column, and TAPT-DVA-COP monolithic column.

[0118] 1) SEM of the entire column is shown in [image / image]. Figure 12 .Depend on Figure 12 It can be seen that the TAPT-DVA-COP monolithic column, COP-SO3H monolithic column, and COP-CD monolithic column exhibit a uniform and continuous three-dimensional porous structure.

[0119] 2) See the FT-IR of the entire column. Figure 13 .Depend on Figure 13 It can be seen that the APT-DVA-COP monolithic column, COP-SO3H monolithic column, and COP-CD monolithic column all exhibit the characteristic absorption peak of the blank monolithic column, and a peak at 1628 cm⁻¹ also appears. -1 (C=N) characteristic peak; in addition, the COP-SO3H monolithic column also has a peak at 563 cm⁻¹. -1 The characteristic peak of CS appeared at 582 cm⁻¹, while the overall COP-CD column was at 582 cm⁻¹. -1 The presence of characteristic peaks of CS indicates the successful preparation of the three types of monolithic columns.

[0120] 3) The nitrogen adsorption characterization of the monolithic column is shown in [reference needed]. Figure 14 .Depend on Figure 14 It can be seen that the specific surface area of ​​the COP-SO3H monolithic column is approximately 20.6 m². 2The specific surface area of ​​the COP-CD monolithic column was approximately 22.2 m² / g, significantly higher than that of the blank monolithic column; the pore size was 13.4 nm. 2 / g, significantly higher than the blank monolithic column; pore size is 15.9 nm.

[0121] III. Applications of the COP-SO3H Monolithic Column Prepared by this Invention

[0122] Example 5: Application of COP-SO3H monolithic column in the separation of monosubstituted benzenes

[0123] In this embodiment, a mixed solution of benzoic acid, benzyl alcohol, benzaldehyde, anisole, chlorobenzene, bromobenzene, and iodobenzene was prepared using acetonitrile, with each monosubstituted benzene having a concentration of 3 mg / mL. -1 The mixed solution was analyzed using a CEC-UV (COP-SO3H monolithic column). The CEC-UV conditions were: mobile phase of pH 7.0, 5 mM phosphate buffer, and acetonitrile (acetonitrile volume fraction 45%), operating voltage of -15 kV, and detection wavelength of 220 nm. This invention also investigated the separation efficiency of the TAPT-DVA-COP monolithic column for benzoic acid, benzyl alcohol, benzaldehyde, anisole, chlorobenzene, bromobenzene, and iodobenzene under the same conditions. The results are shown in […]. Figure 15 .

[0124] Depend on Figure 15 It can be seen that the elution order of the seven monosubstituted benzenes by the TAPT-DVA-CD monolithic column and the COP-SO3H monolithic column is consistent with their hydrophobic properties, indicating that the elution of monosubstituted benzenes is mainly due to hydrophobic interactions. The COP-SO3H monolithic column, due to the introduction of 1,2-ethanesulfonic acid, enhances the CH…π interaction and hydrogen bonding between the substituted benzenes and the monolithic column, resulting in a stronger retention capacity of the COP-SO3H monolithic column for monosubstituted benzenes. Furthermore, the chromatographic peaks of the COP-SO3H monolithic column are more symmetrical, indicating that the COP-SO3H monolithic column has good separation selectivity and column efficiency for monosubstituted benzenes.

[0125] This invention uses monosubstituted benzene as the analyte and investigates the stability and repeatability of the COP-SO3H monolithic column. The CEC-UV conditions are: mobile phase of pH 7.0, 5 mM phosphate buffer, and acetonitrile (45% acetonitrile by volume); operating voltage of -15 kV; and detection wavelength of 220 nm. The results are shown in Table 1 and [Table data missing]. Figure 16 (a), (b) and (d).

[0126] Table 1. Stability and reproducibility of monosubstituted benzenes on the COP-SO3H monolithic column.

[0127]

[0128] From Table 1 and Figure 16It can be seen that the RSD of the inter-needle (n=10), inter-day (n=5), and inter-column (n=3) retention times of monosubstituted benzenes are all less than 5.04%, indicating that the COP-SO3H monolithic column exhibits good repeatability, stability, and precision for monosubstituted benzenes.

[0129] This embodiment also investigated the effect of flow rate on the overall column back pressure of COP-SO3H. Figure 16 (c) It can be seen that the flow rate of different mobile phases (the mobile phases are pH 7.0, 5 mM phosphate buffer and 40% methanol (or 40% acetonitrile or 40% water) and the back pressure of the COP-SO3H monolithic column are linearly related, indicating that the COP-SO3H monolithic column of the present invention has good mechanical stability.

[0130] This embodiment also explored the specific interaction forces between COP-SO3H and four monosubstituted benzenes (benzoic acid, benzyl alcohol, anisole, and benzaldehyde). Figure 17 As shown, the benzene ring of COP-SO3H exhibits π…π interactions with the benzene ring structures of the analytes (benzyl alcohol and benzaldehyde), and the sulfonic acid groups of COP-SO3H also exhibit OH…O hydrogen bonding with the analytes (benzoic acid, benzyl alcohol, and benzaldehyde). The lone pair electrons of the oxygen in the substituents of the analytes (anisole and benzaldehyde) can approach the conjugated system of COP-SO3H, forming LP…π interactions. The carbon chains in COP-SO3H exhibit CH…π interactions with the benzene rings in the structures of the analytes (benzoic acid and anisole). These forces contribute to the good separation performance of the monolithic COP-SO3H column.

[0131] Example 6: Application of the COP-SO3H monolithic column prepared in this invention in the separation of charged small molecules.

[0132] 1. In this study, benzoic acid, toluene, tyramine, histamine, and tryptamine were used as analytes to investigate the separation mechanism of the COP-SO3H monolithic column. The detection conditions were: 5 mM phosphate buffer (pH 2.5-6.0), 50% acetonitrile, -15 kV, 220 nm.

[0133] Depend on Figure 18 (a) It can be seen that the resolution of toluene is basically unaffected by the pH of the buffer solution. When the pH of the buffer solution increases from 3.0 to 6.0, the retention of benzoic acid (pKa=4.2) decreases significantly. The sulfonic acid groups on the surface of the stationary phase of the COP-SO3H monolithic column dissociate and become negatively charged, while benzoic acid also exists in a negatively charged state, resulting in electrostatic repulsion between benzoic acid and the stationary phase. Biogenic amines exist in a positively charged state and are electrostatically attracted to COP-SO3H, so the retention of biogenic amines increases with increasing pH. It can be seen that the separation mechanism of the COP-SO3H column is a mixed mode of weak cation exchange chromatography and reversed-phase chromatography.

[0134] 2. This example investigated the separation performance of the COP-SO3H monolithic column for nucleoside bases (including uracil, cytosine, and 6-chloro-7-azapurine) and biogenic amines (tyramine, histamine, and tryptamine). The CEC-UV conditions for nucleoside bases were as follows: pH 7.0, 5 mM phosphate buffer, 50% acetonitrile, -15 kV, 220 nm. The separation results are shown in [Figure number missing]. Figure 18 (b); The CEC-UV conditions for biogenic amines were: pH 5.0, 5 mM phosphate buffer, 80% acetonitrile, -15 kV, 220 nm. The separation results are shown in [reference needed]. Figure 18 (c).

[0135] Depend on Figure 18 (b) It is evident that the TAPT-DVA-COP monolithic column cannot achieve baseline separation of the three nucleoside bases, while the COP-SO3H monolithic column can, with more symmetrical peak shapes and significantly improved resolution. This is due to ion exchange and hydrogen bonding interactions between the nucleoside bases in the COP-SO3H monolithic column. The results indicate that the introduction of sulfonic acid groups can significantly enhance the affinity of COP-SO3H for relatively polar compounds.

[0136] Depend on Figure 18 (c) It can be seen that compared with the TAPT-DVA-COP monolithic column, the COP-SO3H monolithic column can achieve high selective separation of three biogenic amines in a short time. The main reason is the synergistic effect of hydrophobic interaction and ion exchange between biogenic amines and stationary phase, which further proves that the COP-SO3H stationary phase has a good affinity for polar compounds.

[0137] In summary, the COP-SO3H monolithic column has good separation potential for polar charged small molecules.

[0138] Example 7: Application of the COP-SO3H monolithic column of the present invention in the separation of p-hydroxybenzoic acid esters

[0139] 1. This example investigated the separation efficiency of COP-SO3H monolithic column and TAPT-DVA-COP monolithic column for p-hydroxybenzoic acid esters. The detection conditions were: pH 7.0, 5 mM phosphate buffer, 30% acetonitrile, -15 kV, 220 nm. The results are shown in [Figure number missing]. Figure 19 (a).

[0140] Depend on Figure 19(a) It is evident that the TAPT-DVA-COP monolithic column cannot achieve baseline separation of the four p-hydroxybenzoic acid esters. However, the introduction of 1,2-ethanesulfonic acid into the COP-SO3H monolithic column enhances the CH…π interaction and hydrogen bonding between the analytes and the COP-SO3H monolithic column, resulting in better retention capacity and achieving baseline separation of the four analytes with more symmetrical peaks. The results indicate that the COP-SO3H monolithic column can be used for the separation of p-hydroxybenzoic acid esters.

[0141] 2. In this embodiment, the COP-SO3H monolithic column was used for the detection of parabens in cosmetics. The separation conditions were: pH 7.0, 5 mM phosphate buffer, 27% acetonitrile, -15 kV, 220 nm.

[0142] First, using paraben standards as analytes, the standard curve, limit of detection, and limit of quantitation for parabens were determined, as detailed in Table 2.

[0143] Table 2. Standard curves, limits of detection, and limits of quantitation for four p-hydroxybenzoic acid esters.

[0144]

[0145] Table 2 shows that the linear correlation coefficients of the standard curves for the four parabens ranged from 0.994 to 0.999, indicating a good linear relationship between the concentration and peak area of ​​the four parabens. The limits of quantitation and limits of detection for the four parabens were determined at S / N = 10 and S / N = 3, respectively. The results indicate that COP-SO3H has high sensitivity and accuracy and can be used for the quantitative detection and analysis of preservatives in cosmetics.

[0146] Secondly, the powdered components of the cosmetic powder were dissolved in methanol, sonicated, and centrifuged at 10,000 r / min for 10 min. The resulting supernatant was concentrated twice to the sample to be tested, and then detected by CEC-UV.

[0147] To verify the reliability of the detection method of this invention, mixed standard samples were added to cosmetics, and the spiked recoveries and RSDs of p-hydroxybenzoic acid esters were calculated. The results are shown in Table 3 and 4. Figure 19 (b).

[0148] Table 3 Spiked recoveries and RSDs of p-hydroxybenzoic acid esters

[0149]

[0150] ND: Not detected

[0151] From Table 3 and Figure 19(b) It is evident that methylparaben and propylparaben were found in the actual sample, while the other two parabens were not detected. Spiked recovery tests showed that the recovery rate of paraben preservatives using the method of this invention was 76.7%-122.0%, with RSDs less than 10.0%. The experimental results indicate that the COP-SO3H monolithic column can be used to detect parabens in cosmetics.

[0152] Example 8: Application of COP-SO3H monolithic column in the separation of alkylbenzenes

[0153] 1. In this example, alkylbenzenes (toluene, ethylbenzene, propylbenzene, butadiene, and pentabenzene, prepared with acetonitrile) were used as analytes. The detection conditions were: 5 mM phosphate buffer (pH=7.0), 30%-70% acetonitrile, -15 kV, 220 nm. The results are shown in [Figure number missing]. Figure 20 .

[0154] Depend on Figure 20 (a) It can be seen that the elution order of alkylbenzenes is consistent with their hydrophobicity. When the acetonitrile increases from 30% to 70%, the log k value decreases significantly, which is consistent with the typical reversed-phase separation mechanism. Therefore, the COP-SO3H monolithic column has a reversed-phase chromatography separation mechanism.

[0155] Depend on Figure 20 (b) It can be seen that, compared with the TAPT-DVA-COP monolithic column, the introduction of 1,2-ethanesulfonic acid into the COP-SO3H monolithic column enhances the CH…π interaction and hydrogen bonding between the analyte and the COP-SO3H monolithic column, resulting in better retention of alkylbenzenes by the COP-SO3H monolithic column, enabling baseline separation of alkylbenzenes and more symmetrical chromatographic peaks.

[0156] 2. In this embodiment, the COP-SO3H monolithic column was used for the detection of alkylbenzenes in wastewater. The separation conditions were: pH 7.0, 5mM phosphate buffer, 45% acetonitrile, -15 kV, 220 nm.

[0157] First, a mixed standard solution of alkylbenzene (prepared with acetonitrile, concentration range 0–100 mg / mL) was used. -1 As an analyte, the standard curve, limit of detection, and limit of quantitation of p-hydroxybenzoic acid esters were determined, as detailed in Table 4.

[0158] Table 4 Standard curves, limits of detection, and limits of quantitation for alkylbenzenes

[0159]

[0160] As shown in Table 4, each alkylbenzene ranges from 6.3 to 100.0 mg / mL. -1The linear correlation coefficients within the range were all greater than 0.99, indicating a good linear relationship between the concentration and peak area of ​​the five alkylbenzene pollutants. The limits of quantitation (LOQs) for the five alkylbenzenes (range 1.1–3.3 mg / mL) were determined at S / N = 10 and S / N = 3, respectively. -1 ) and detection limits (0.3-1.0 mg / mL) -1 This indicates that the COP-SO3H monolithic column is suitable for the quantitative detection and analysis of alkylbenzenes in wastewater.

[0161] Secondly, the three wastewater samples were diluted twice with methanol, filtered through a 0.22 µm filter membrane to remove impurities, and then the alkylbenzenes in the three samples were quantitatively analyzed by CEC-UV under the same separation conditions.

[0162] To verify the reliability of the detection method of this invention, a mixed standard solution was added to each sample, and the spiked recoveries and RSDs of alkylbenzene were calculated. The results are shown in Table 5 and 6. Figure 20 (c).

[0163] Table 5 Spiked recoveries and RSDs of alkylbenzenes

[0164]

[0165] Note: ND in Table 5 means not detected.

[0166] From Table 5 and Figure 20 (c) It is known that toluene and ethylbenzene were detected only in sample 3; the spiked data showed that the recovery rate of alkylbenzene contaminants was 76.6%-128.7%, and the RSDs were 1.0%-13.9%. The results indicate that the CEC-UV detection method based on the COP-SO3H monolithic column of this invention can be used for the separation and quantitative detection of alkylbenzenes in complex matrices.

[0167] IV. Applications of the COP-CD monolithic column prepared by this invention

[0168] Example 9 Application of the COP-CD monolithic column prepared in this invention in the separation of alkylbenzenes

[0169] 1. This example investigated the separation mechanism of the COP-CD monolithic column, specifically using alkylbenzenes (toluene, ethylbenzene, propylbenzene, butadiene, and pentanylbenzene, prepared with acetonitrile) as analytes. The detection conditions were: 5 mM phosphate buffer (pH=7.0), 40%-60% acetonitrile, -15 kV, 220 nm. The results are shown in [Figure number missing]. Figure 21 (a) and Figure 21 (b).

[0170] Depend on Figure 21(a) It can be seen that the elution order of alkylbenzenes is consistent with their hydrophobicity. When the acetonitrile content increases from 40% to 60%, the log k value decreases significantly, which is consistent with the typical reversed-phase separation mechanism. Therefore, the COP-CD monolithic column has a reversed-phase chromatography separation mechanism.

[0171] Depend on Figure 21 (b) It is evident that, compared to the TAPT-DVA-CD monolithic column, alkylbenzenes achieve good baseline separation, higher resolution, and more symmetrical chromatographic peaks on the COP-CD monolithic column. Alkylbenzenes also exhibit longer retention times on the COP-CD monolithic column, demonstrating excellent separation selectivity and column efficiency. This is because the introduction of β-CD enhances the hydrogen bonding between the monolithic column and the analyte, thereby improving the separation selectivity of the COP-CD monolithic column.

[0172] 2. In this embodiment, the reproducibility of the COP-CD monolithic column was also investigated using alkylbenzene as the analyte. The detection conditions were 5 mM phosphate buffer (pH=7.0), 40% acetonitrile, -15 kV, 220 nm. The results are shown in Table 6 and [Table data would be inserted here]. Figure 22 (a), (b) and (d).

[0173] Table 6 Reproducibility of COP-CD Overall Columns

[0174]

[0175] From Table 6 and Figure 22 It can be seen that the RSD of the retention times between needles (n=10), between days (n=5), and between columns (n=3) are all less than 2.11%, indicating that the COP-CD monolithic column has good repeatability, stability and high precision for CEC separation.

[0176] 3. In this embodiment, 40% methanol, 40% acetonitrile, and 40% water were used as mobile phases, respectively. Under the same detection conditions (mobile phase: pH 7.0, 5 mM phosphate buffer; operating voltage: -15 kV; detection wavelength: 220 nm), the effect of flow rate on the overall column back pressure of COP-CD was investigated. The results are shown in [Figure number missing]. Figure 22 (c). By Figure 22 (c) It can be seen that there is a linear relationship between the flow rate and the back pressure of the COP-CD monolithic column, indicating that the monolithic column of the present invention has good mechanical stability.

[0177] Example 10: Application of COP-CD monolithic column in the separation of monosubstituted benzenes

[0178] 1. In this embodiment, benzoic acid, benzyl alcohol, benzaldehyde, anisole, chlorobenzene, bromobenzene, and iodobenzene were used as analytes. Analysis was performed using a COP-CD monolithic column and a TAPT-DVA-COP monolithic column, respectively. The detection conditions were: pH 7.0, 5 mM phosphate buffer, and acetonitrile (acetonitrile volume fraction 45%), with an operating voltage of -15 kV and a detection wavelength of 220 nm. The results are shown in [Figure number missing]. Figure 23 (a).

[0179] Depend on Figure 23 (a) It can be seen that, compared with the TAPT-DVA-CD monolithic column, monosubstituted benzene compounds can achieve good baseline separation, higher resolution, more symmetrical chromatographic peaks, and longer retention times on the COP-CD monolithic column. This is because β-CD provides strong hydrogen bonding for the monolithic column. The results show that the COP-CD monolithic column has better separation selectivity and column efficiency.

[0180] 2. The COP-CD monolithic column prepared in this invention was used for the quantitative analysis of monosubstituted benzenes in actual samples.

[0181] First, prepare mixed standard solutions of monosubstituted benzenes at different concentrations (concentration range: 0–1000 mg / mL). -1 The separation column was a COP-CD monolithic column; the detection conditions were as follows: 5 mM phosphate buffer at pH 7.0, 30% acetonitrile, operating voltage of -15 kV, and operating wavelength of 220 nm. The standard curves, limits of detection, and limits of quantitation for the four alkylbenzenes are shown in Table 7.

[0182] Table 7 Standard curves, limits of detection, and limits of quantitation for monosubstituted benzenes

[0183]

[0184] Table 7 shows that the concentrations in the range of 7.8-1000 mg / mL are... -1 Within the specified range, the linear correlation coefficients of the standard curves for the four monosubstituted benzenes were between 0.998 and 0.999, indicating a good linear relationship between the concentration and peak area of ​​the monosubstituted benzenes. The limits of quantitation and limits of detection for the four monosubstituted benzenes were obtained at S / N = 10 and S / N = 3, respectively, demonstrating that the COP-CD monolithic column is suitable for the quantitative detection of the four monosubstituted benzenes and has certain feasibility for the detection and analysis of toluene, chlorobenzene, bromobenzene, and iodobenzene in wastewater.

[0185] Next, the wastewater samples were filtered through a 0.22 µm filter membrane to remove impurities, and then analyzed. Simultaneously, to verify the reliability of the detection method of this invention, a mixed standard solution was added to each sample, and the spiked samples were analyzed under the same detection conditions as in step S1. The spiked recoveries and RSDs of monosubstituted benzenes were calculated, and the results are shown in Table 8. Figure 23 (b).

[0186] Table 8 Spike recoveries and RSDs of monosubstituted benzenes

[0187]

[0188] Note: ND in Table 8 means not detected.

[0189] From Table 5 and Figure 23 (b) It can be seen that chlorobenzene and iodobenzene were detected only in sample 3; the spiked detection results showed that the recovery rate of the four monosubstituted benzenes was 73.0%-109.1%, and the RSD was less than 9.0%, indicating that the CEC-UV detection method based on the COP-CD monolithic column of the present invention can be used for the separation and quantitative detection analysis of alkylbenzenes in actual samples.

[0190] Example 11: Application of COP-CD monolithic column in the separation of phenolic substances

[0191] This embodiment uses hydroquinone, p-methoxyphenol, phenol, and p-methylphenol as analytes, analyzed using a COP-CD monolithic column and a TAPT-DVA-COP monolithic column, respectively. The detection conditions are: pH 7.0, 5 mM phosphate buffer, and acetonitrile (acetonitrile volume fraction 38%), operating voltage -15 kV, and wavelength 220 nm. Results are shown in [Figure number missing]. Figure 24 (a).

[0192] Depend on Figure 24 (a) It can be seen that, compared with the TAPT-DVA-COP monolithic column, the retention time of acidic phenolic substances on the COP-CD monolithic column is increased, and the selectivity and resolution are significantly improved. The introduction of β-CD increases the hydrogen bonding between the chromatographic stationary phase and the analyte, thereby improving the separation selectivity and retention capacity of the COP-CD monolithic column for the analyte.

[0193] This embodiment also analyzes the interaction forces between COP-CD and hydroquinone, p-methoxyphenol, phenol, and p-methylphenol. Figure 25 It is evident that the introduction of β-cyclodextrin leads to various interactions between COP-CD and the analytes, including OH…O hydrogen bonding, LP…π interactions, CH…π interactions, and π…π interactions. For example, hydrogen bonding exists between the cyclodextrin in COP-CD and all analytes; LP…π interactions exist between the lone pair electrons of the β-cyclodextrin hydroxyl oxygen and the benzene ring in the analyte, and CH…π interactions exist between the carbon chain and the benzene ring in the analyte structure; π…π interactions exist between the benzene ring in the analyte and the COP-CD conjugated system. These interactions ensure the separation performance of the COP-CD monolithic column.

[0194] Example 12 Application of COP-CD monolithic column in isomer separation

[0195] This embodiment uses p-nitrophenol, m-nitrophenol, and o-nitrophenol as analytes, analyzed using a COP-CD monolithic column and a TAPT-DVA-COP monolithic column, respectively. The detection conditions are: pH 7.0, 5 mM phosphate buffer, and acetonitrile (acetonitrile volume fraction 40%), operating voltage -15 kV, and wavelength 220 nm. Results are shown in [Figure number missing]. Figure 24 (b).

[0196] Depend on Figure 24 (b) It is evident that, due to the identical hydrophobicity of the three analytes (Log P 1.82), the TAPT-DVA-COP monolithic column, which relies primarily on hydrophobic interactions, cannot separate the ortho, meta, and para-nitrophenol isomers. Compared to the TAPT-DVA-COP monolithic column, the β-CD cavity in the COP-CD monolithic column exhibits spatial selectivity for the isomers, and different hydrogen bonding interactions exist between the COP-CD and the nitrophenol isomers. The hydrogen bonding interaction between para-nitrophenol and the COP-CD monolithic column is the weakest, resulting in para-nitrophenol being eluted first. The hydroxyl and nitro groups of ortho-nitrophenol are closer and more prone to forming hydrogen bonds, leading to the strongest retention on the COP-CD monolithic column. This achieves baseline separation of the nitrophenol isomers on the COP-CD monolithic column.

[0197] Example 13 Application of COP-CD monolithic column in the separation of chiral substances

[0198] This embodiment uses four chiral substances—ractopamine, flavanones, propranolol, and binatrol—as analytes. Analysis was performed using a COP-CD monolithic column and a TAPT-DVA-COP monolithic column, respectively. The detection conditions for ractopamine and binatrol were: pH 5.0, 5 mM phosphate buffer, and acetonitrile (90% acetonitrile volume fraction), operating voltage -15 kV, and wavelength 210 nm. The detection conditions for flavanones and propranolol were: pH 5.0, 5 mM phosphate buffer, and acetonitrile (70% acetonitrile volume fraction), operating voltage -15 kV, and wavelength 210 nm. The chromatographic separation results are shown in [Figure number missing]. Figure 26 .

[0199] Depend on Figure 26 It can be seen that the TAPT-DVA-COP monolithic column cannot achieve the separation of any chiral substances; the COP-CD monolithic column showed a certain separation ability for all four chiral substances in reverse phase mode and achieved baseline separation of ractopamine.

[0200] In summary, the sulfonic acid-functionalized vinyl covalent organic polymers and cyclodextrin-functionalized vinyl covalent organic polymers prepared in this invention, when used as stationary phase materials for CEC, exhibit excellent separation performance due to the presence of OH…O hydrogen bonds, LP…π interactions, CH…π interactions, and π…π interactions. These properties enable the prepared monolithic columns to be used not only for the selective separation of various neutral small molecule compounds but also for the selective separation of charged small molecules. Furthermore, they are suitable for the selective separation of phenolic substances, the selective separation of isomers, and the resolution of chiral molecules, providing a novel solid-phase material for CEC and holding significant importance.

Claims

1. Functionalized vinyl covalent organic polymer as capillary monolithic column stationary phase material, applied to the selective separation of neutral small molecule compounds, charged small molecule compounds; wherein, The neutral small molecule compound is selected from monosubstituted benzene, alkyl benzene and p-hydroxy benzoic acid ester, the monosubstituted benzene is selected from benzoic acid, benzyl alcohol, benzaldehyde, benzyl ether, chlorobenzene, bromobenzene and iodobenzene; the alkyl benzene is selected from methyl benzene, ethyl benzene, propyl benzene, butyl benzene and amyl benzene; the p-hydroxy benzoic acid ester is selected from methyl p-hydroxy benzoate, ethyl p-hydroxy benzoate, propyl p-hydroxy benzoate and butyl p-hydroxy benzoate; the charged small molecule compound is selected from nucleoside base and biological amine, the nucleoside base is selected from uracil, cytosine and 6-chloro-7-azapyrimidine, and the biological amine is selected from tyramine, histamine and tryptamine; The preparation method of the functionalized vinyl covalent organic polymer comprises the following contents: In the first step, monomers 2,5-divinyl-1,4-benzaldehyde and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine are dissolved in an organic solvent at a molar ratio of 1:1 to 4:3, a catalyst is added, and the reaction is carried out at room temperature for 24 to 96 hours; after the reaction is completed, the precipitate is obtained by centrifugation or filtration, washed, dried, and the vinyl covalent organic polymer TAPT-DVA-COP is obtained; In the second step, TAPT-DVA-COP, a modification reagent and azobisisobutyronitrile are mixed in anhydrous ethanol to obtain a suspension, and the suspension is stirred in a nitrogen environment for 24 to 96 hours; after the reaction is completed, the precipitate is obtained by centrifugation or filtration, washed, dried, and the functionalized vinyl covalent organic polymer is obtained; the modification reagent is 1,2-ethanedithioic acid; The capillary monolithic column is prepared by using the functionalized vinyl covalent organic polymer as the stationary phase, and the following steps are specifically used: S1, the inner wall surface of the capillary is silanized; S2, the functionalized vinyl covalent organic polymer is added to the polymerization solution, ultrasonically mixed, and the mixed pre-polymerization solution is injected into the capillary in the first step, and the polymerization reaction is carried out at 50 to 70 DEG C for 10 to 20 hours; The polymerization solution is prepared by using glycidyl methacrylate and ethylene glycol dimethacrylate as monomers, n-propanol and 1,4-butanediol as porogens, azobisisobutyronitrile as an initiator, and 2-acrylamide-2-methyl-1-propanesulfonic acid as an electroosmotic flow generator, the volume ratio of the monomers and the porogens is 1 / 9 to 4 / 6, the volume ratio of glycidyl methacrylate and ethylene glycol dimethacrylate is 1:1, and the volume ratio of n-propanol and 1,4-butanediol is 1:1; S3, after the reaction is completed, the capillary is washed with pure methanol mobile phase to remove the unreacted polymerization solution, and then dried with nitrogen; the polyimide at the effective column end of the monolithic column is removed to form a detection window, and the capillary monolithic column with the functionalized vinyl covalent organic polymer as the stationary phase is obtained.

2. Use according to claim 1, characterized in that: In the first step, the washing is carried out by using anhydrous ethanol, tetrahydrofuran and acetone in sequence for 2 to 5 times; in the second step, the washing is carried out by using acetone and anhydrous ethanol alternately for 2 to 5 times; the drying conditions in the first step and the second step are the same, and the drying is carried out under vacuum conditions, wherein the drying temperature is 50 to 80 DEG C, and the drying time is ≥24 hours.

3. Use according to claim 1, characterized in that: In the first step, the organic solvent is methanol, acetonitrile or ethylene glycol.

4. Use according to claim 1, characterized in that: The mass ratio of TAPT-DVA-COP, sulfonic acid compound and azobisisobutyronitrile in the second step is (10-30):(30-90):(1-5).

5. The use according to claim 1, characterized in that: The amount of the functionalized vinyl covalent organic polymer incorporated in the mixed solution in the step S2 is less than 20 mg mL -1 .

6. Use according to claim 1, characterized in that: In the selective analysis of neutral small molecule compounds and charged small molecule compounds, CEC-UV is used for quantitative detection analysis; wherein, the detection conditions of CEC-UV are as follows: buffer and acetonitrile are used as mobile phases, the working voltage is-10 kV to-20 kV, and the wavelength is 210 nm to 220 nm; the volume fraction of acetonitrile in the mobile phase is 20% to 90%, and the pH of the buffer is 3.0 to 7.

0.

7. Use according to claim 6, characterized in that: The buffer is NaH2PO4 buffer, and the concentration is 5 mM.

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