Multi-mode liquid chromatography filler of ionic liquid hydrogel modified silica gel as well as preparation and application of multi-mode liquid chromatography filler

Abstract

The invention discloses a multi-mode liquid chromatography filler of ionic liquid hydrogel modified silica gel and preparation and application thereof, and the method comprises the following steps: fully dissolving an ionic liquid hydrogel monomer and a cross-linking agent in a polar aprotic organic solvent, adding silica gel, carrying out ultrasonic treatment, and standing; adding an initiator, stirring, condensing, refluxing, stirring and reacting at 70-80 DEG C in an inert atmosphere; and drying under stirring, centrifugally washing and drying. According to the invention, the problems of single functional group, tedious modification steps, low ligand density and poor high-pressure stability in the existing method are solved. The preparation method is simple and convenient, efficient modification of hydrogel on the surface of silica gel can be achieved, and the prepared liquid chromatography packing has good separation selectivity on nucleoside / basic groups, organic acid compounds, alkaloid, antibiotics, aniline compounds, anion-containing compounds and the like; and chromatographic separation in a hydrophilic chromatographic mode, a hydrophobic chromatographic mode and an ion exchange chromatographic mode can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high performance liquid chromatography separation and analysis, and particularly relates to a kind of ionic liquid hydrogel modified silica gel multi-mode liquid chromatography packing and its preparation and application. BACKGROUND

[0002] The matrix of liquid chromatography stationary phase is mainly divided into two categories of inorganic and organic. The inorganic matrix is most widely used with silica gel, which has adjustable particle size, high mechanical strength and large specific surface area, and is the mainstream choice of commercial packing, accounting for more than 90%. Traditional modification methods use chlorosilane or alkoxysilane to react with surface silanol groups to form Si-O-Si-C monolayer bonded phase. However, due to the limitation of steric hindrance and silanol group density (≈5 / nm²), only 40-50% of the silanol groups can participate in the reaction, and the residual silanol groups are prone to secondary reactions with basic compounds, resulting in peak tailing and column efficiency decline. To alleviate this problem, the industry has developed an "end-capping" process, but it cannot completely eliminate the activity of silanol groups, and under high pH or high temperature conditions, the Si-O-Si-C bond is easy to hydrolyze, causing ligand loss and shortening the service life. Organic polymer matrix (cross-linked polystyrene, polymethacrylate, etc.) has good pH resistance and biocompatibility, but it will swell / contract when the mobile phase changes, the pore size distribution will widen, the mass transfer resistance will be large, and the column efficiency for small molecule separation will be significantly lower than that of inorganic matrix. In addition, traditional single-mode bonded phases (C18, cyano and phenyl, etc.) have limited selectivity, and multiple chromatographic modes often need to be switched when facing complex samples, increasing the method development time and solvent consumption.

[0003] To break through the limitation of single mode, the existing document 1 (Liu Jiawei, Tang Changwei, Xia Yiran, et al. Application progress of chromatographic techniques in antibody separation and purification [J]. Chromatography, 2024, 42(06): 533-543) proposes a mixed-mode stationary phase, which introduces ion exchange and hydrophobic groups onto the surface of silica gel at the same time, and can consider the differences in polarity, charge and hydrophobicity in one separation. However, this mixed-mode packing material usually adopts a two-step method of “chemical bonding + subsequent modification”: first, introduce hydrophobic chains by silanization, and then graft ion groups through secondary reaction. The following disadvantages exist: (1) multiple reaction steps, low yield, and poor batch reproducibility; (2) the amount of ion groups introduced is limited by the number of remaining silanol groups on the surface, and the exchange capacity is insufficient; (3) the ligand distribution is uneven, and “hot spots” are easily generated, resulting in peak tailing. Among them, imidazole IL has been tried to be used as a new ligand due to its strong designability, almost no volatilization and high thermal stability. The imidazole IL is covalently bonded to the surface of silica gel to prepare an antibody separation packing material with ion exchange and hydrophobic interaction, but the synthesis needs multiple organic reactions, and the IL grafting density is low (<0.8 μmol m⁻²), which fails to fully exert the multi-mode advantage of IL. The three-dimensional network of hydrogel can provide a large number of active sites and relieve the secondary effect of silanol groups, but the mechanical strength of hydrogel is poor and it is easy to collapse under high pressure in HPLC, which has not been applied in practice.

[0004] In summary, the existing technology has the following bottlenecks: “single functional group, complicated modification steps, low ligand density, and poor high-pressure stability”, which is difficult to meet the needs of one-time high-efficiency separation of samples with large polarity span and complex matrix. Therefore, it is urgent to develop a new type of chromatographic packing material with simple preparation, high ligand density, good mechanical strength and multiple hydrophilic / hydrophobic / ionic exchange effects in the field of liquid chromatography stationary phase. SUMMARY

[0005] The purpose of the present application is to provide a kind of ionic liquid hydrogel modified silica gel multi-mode liquid chromatography packing and its preparation and application, solve the problem of single functional group in the prior art method, complicated modification steps, low ligand density and poor high-pressure stability, the preparation method is simple and can realize the efficient modification of hydrogel on the surface of silica gel, the prepared liquid chromatography packing has good separation selectivity for nucleoside / base, organic acid compound, alkaloid, antibiotic, aniline compound and anion, which is helpful to realize chromatographic separation in hydrophilic chromatography mode, hydrophobic chromatography mode and ion exchange chromatography mode.

[0006] In order to achieve the above purpose, the present application provides a kind of ionic liquid hydrogel modified silica gel multi-mode liquid chromatography packing preparation method, which comprises: (1) Dissolve the ionic liquid hydrogel monomer and the crosslinking agent in a polar aprotic organic solvent to obtain an ionic liquid hydrogel prepolymer solution; The ionic liquid hydrogel monomer is any one or more than two of 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazole bromide; (2) Add silica gel to the ionic liquid hydrogel prepolymer solution, ultrasonically treat, and stand still; (3) Add an initiator and stir, condense and reflux under stirring at 70-80°C in an inert atmosphere; (4) After the reaction is completed, dry under stirring to obtain a solid product, centrifugally wash with deionized water and anhydrous ethanol, and dry to obtain a multi-mode liquid chromatography packing prepared by modifying ionic liquid hydrogel to the surface of silica gel.

[0007] Preferably, in step (1), the polar aprotic organic solvent is dimethyl sulfoxide, the crosslinking agent is N,N'-methylenebisacrylamide, and the mass ratio of the ionic liquid hydrogel monomer and the crosslinking agent is (15-20):1.

[0008] Preferably, in step (1), the ionic liquid hydrogel monomer is 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazole bromide.

[0009] Preferably, the mass ratio of the 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazole bromide is 5:4:(15-20).

[0010] Preferably, in step (2), the mass ratio of the silica gel and the ionic liquid hydrogel monomer is (1-4):1.

[0011] Preferably, in step (3), the initiator is any one of azobisisobutyronitrile, ammonium persulfate, hydrogen peroxide and dicumyl peroxide.

[0012] Preferably, in step (3), the mass ratio of the initiator and the silica gel is 1:(35-40), and the stirring speed is 150-300 rpm.

[0013] Preferably, in step (4), the drying temperature is 120-140°C, and the drying temperature is 85-95°C.

[0014] The application provides a multi-mode liquid chromatography packing prepared by the method.

[0015] The application provides application of the multi-mode liquid chromatography packing in the field of chromatographic separation.

[0016] Preferably, the application includes separation of nucleosides / bases, organic acid compounds, alkaloids, antibiotics, aniline compounds and compounds containing anions (SCN - , NO3 - , NO2 - and Br - ) and the like.

[0017] The ionic liquid hydrogel modified silica gel multi-mode liquid chromatography packing material of the present application and its preparation and application solve the problems of single functional group, complicated modification steps, low ligand density and poor high-pressure stability in the prior art, and has the following advantages: 1. The present application uses physical coating technology to obtain a multi-mode liquid chromatography packing material prepared by physically coating ionic liquid hydrogel on the surface of silica gel, wherein the ionic liquid hydrogel is prepared from 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazole bromide, and the preparation method is simple and can realize efficient modification of hydrogel on the surface of silica gel.

[0018] 2. The prepared hydrogel has multiple properties (hydrophilicity, hydrophobicity and ion exchange) and a three-dimensional network structure, so that the multi-mode liquid chromatography packing material can be used for separation and analysis of different polar compounds, and can achieve chromatographic separation performance that is difficult to achieve by silica gel modified by a single monomer or two monomers, and has good separation selectivity for nucleosides / bases, organic acid compounds, alkaloids, antibiotics, aniline compounds and compounds containing anions (SCN - , NO3 - , NO2 - and Br - ) and the like. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 SEM images of silica gel modified by the ionic liquid hydrogel prepared in Example 1 of the present application and bare silica gel.

[0020] Figure 2 FT-IR images of silica gel modified by the ionic liquid hydrogel prepared in Example 1 of the present application and bare silica gel.

[0021] Figure 3 Thermogravimetric images of silica gel modified by the ionic liquid hydrogel prepared in Example 1 of the present application and bare silica gel.

[0022] Figure 4 Schematic diagram of the multi-mode liquid chromatography column of the ionic liquid modified silica gel prepared in Example 1 of the present application in separating nucleosides / bases under the condition that the mobile phase is acetonitrile / 100 mM ammonium acetate (87 / 13, v / v).

[0023] Figure 5 Schematic diagram of separation of organic acids by the multi-modal liquid chromatography column of ionic liquid-modified silica gel prepared in Example 1 of the present application under the condition of mobile phase: acetonitrile / 200 mM ammonium acetate (83 / 17, v / v).

[0024] Figure 6 Schematic diagram of separation of alkaloids by the multi-modal liquid chromatography column of ionic liquid-modified silica gel prepared in Example 1 of the present application under the condition of mobile phase: acetonitrile / 100 mM ammonium acetate (87 / 13, v / v).

[0025] Figure 7 Schematic diagram of separation of anilines by the multi-modal liquid chromatography column of ionic liquid-modified silica gel prepared in Example 1 of the present application under the condition of mobile phase: acetonitrile / water (10 / 90, v / v).

[0026] Figure 8 Schematic diagram of separation of anions by the multi-modal liquid chromatography column of ionic liquid-modified silica gel prepared in Example 1 of the present application under the condition of mobile phase: acetonitrile / 20 mM sodium chloride (85 / 15, v / v).

[0027] Figure 9 Comparison diagram of separation of antibiotics by the chromatography column of ionic liquid hydrogel-modified silica gel prepared in Example 1 of the present application, the chromatography column of silica gel modified by one monomer (Comparative Example 1) and the chromatography column of silica gel modified by two monomers (Comparative Example 2) under the condition of mobile phase: acetonitrile / 100 mM ammonium acetate (60 / 40, v / v).

[0028] Figure 10 Comparison diagram of separation of anions by the chromatography column of ionic liquid hydrogel-modified silica gel prepared in Example 1 of the present application, the chromatography column of silica gel modified by one monomer (Comparative Example 1) and the chromatography column of silica gel modified by two monomers (Comparative Example 2) under the condition of mobile phase: acetonitrile / 20 mM sodium chloride (85 / 15, v / v). DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0030] Example 1 A method for preparing a multi-modal liquid chromatography packing of ionic liquid hydrogel-modified silica gel, comprising: (1) Take 0.25 g of 4-vinylphenylboronic acid, 0.2 g of 1-vinyl-2-pyrrolidone and 0.9 g of 1-vinyl-3-butylimidazole bromide in 40 mL of dimethyl sulfoxide until fully dissolved; after stirring evenly, add 0.08 g of N,N'-methylenebisacrylamide (crosslinking agent) to obtain a hydrogel pre-polymer solution.

[0031] (2) Take 3.0 g of silica gel and add it to the above hydrogel pre-polymer solution, ultrasonic for 30 min to obtain suspension A.

[0032] (3) Take 0.08 g of azobisisobutyronitrile (initiator) and add it to suspension A under magnetic stirring to obtain solution B, heat the obtained solution B in a 75°C water bath, introduce inert gas N2 for 20 min to expel air in the system, condense reflux and heat to 75°C under 150 rpm magnetic stirring for 5 h; (4) After the reaction is completed, evaporate deionized water under slow magnetic stirring and heating to 130°C to obtain a solid product, which is washed with deionized water and anhydrous ethanol for 3 times respectively; place it in a 85°C vacuum drying oven for drying for 24 h to obtain a multi-mode liquid chromatography packing prepared by modifying ionic liquid hydrogel on the surface of silica gel.

[0033] Example 2 The preparation method of the multi-mode liquid chromatography packing of the ionic liquid hydrogel modified silica gel is basically the same as that of Example 1, with the difference being: In step (3), the azobisisobutyronitrile (initiator) is adjusted to ammonium persulfate, hydrogen peroxide or peroxide dichloride, and the mass remains unchanged.

[0034] Comparative Example 1 The preparation method of the multi-mode liquid chromatography packing of the ionic liquid hydrogel modified silica gel (a monomer (4-vinylphenylboronic acid) modified silica gel chromatography packing) is basically the same as that of Example 1, with the difference being: In step (1), the monomer only contains 4-vinylphenylboronic acid, and the amount remains unchanged.

[0035] Comparative Example 2 The preparation method of the multi-mode liquid chromatography packing of the ionic liquid hydrogel modified silica gel (a monomer (4-vinylphenylboronic acid) modified silica gel chromatography packing) is basically the same as that of Example 1, with the difference being: In step (1), the monomer only contains 4-vinylphenylboronic acid, and the amount remains unchanged.

[0036] Comparative Example 3 The preparation method of the multi-mode liquid chromatography packing of the ionic liquid hydrogel modified silica gel (a monomer (4-vinylphenylboronic acid) modified silica gel chromatography packing) is basically the same as that of Example 1, with the difference being: There is no step (1).

[0037] Experimental Example 1: Separation of Nucleosides / Bases Preparation of a multimode liquid chromatography column modified with ionic liquid hydrogel: The multimode liquid chromatography packing material prepared in Example 1 was packed into a 150 × 4.6 mm stainless steel liquid chromatography column using a high-pressure homogenization method for the separation and analysis of nucleosides / bases (including thymine, thymidine, 6-chlorouracil, vidarabine, and cytosine). During packing, both the dispersion and displacement solvent were methanol, and the pressure was 40 MPa.

[0038] Chromatographic separation of nucleosides / bases: Chromatographic analysis conditions were as follows: mobile phase: acetonitrile / 100 mM ammonium acetate (87 / 13, v / v); flow rate: 1.0 mL / min; UV detector: 258 nm; injection volume: 20 µL.

[0039] like Figure 4 The diagram shows the separation of nucleosides / bases using the ion-liquid-modified silica gel multimode liquid chromatography column prepared in Example 1 of this invention, under the mobile phase of acetonitrile / 100 mM ammonium acetate (87 / 13, v / v). Peak 1 represents thymine; peak 2 represents thymidine; peak 3 represents 6-chlorouracil; peak 4 represents vidarabine; and peak 5 represents cytosine. Figure 4 As can be seen, this multimode liquid chromatography packing material exhibits excellent separation selectivity for nucleosides / bases. Specifically, the column efficiency for arabinoside was 44338.6, while the resolution R for thymidine and 6-chlorouracil was 3.365, successfully achieving baseline separation.

[0040] Experimental Example 2: Separation of Organic Acids Preparation of a multimode liquid chromatography column modified with ionic liquid hydrogel: The multimode liquid chromatography packing material prepared in Example 1 was packed into a 150 × 4.6 mm stainless steel liquid chromatography column using a high-pressure homogenization method. This column was used for the separation and analysis of organic acid compounds (including 4-nitrobenzoic acid, 4-chlorobenzoic acid, trans-cinnamic acid, benzoic acid, p-hydroxybenzoic acid, and 5,5'-dithiobis(2-nitrobenzoic acid)). During packing, both the dispersion and displacement solvent were methanol, and the pressure was 40 MPa.

[0041] Chromatographic separation of organic acid compounds: The chromatographic analysis conditions were as follows: mobile phase: acetonitrile / 200 mM ammonium acetate (83 / 17, v / v); flow rate: 1.0 mL / min; UV detector: 226 nm; injection volume: 20 µL.

[0042] like Figure 5The diagram shows the separation of organic acid compounds using the ion-liquid-modified silica gel multimode liquid chromatography column prepared in Example 1 of this invention, under the mobile phase of acetonitrile / 200 mM ammonium acetate (83 / 17, v / v); peak 1 is 4-nitrobenzoic acid; peak 2 is 4-chlorobenzoic acid; peak 3 is trans-cinnamic acid; peak 4 is benzoic acid; peak 5 is p-hydroxybenzoic acid; and peak 6 is 5,5'-dithiobis(2-nitrobenzoic acid). Figure 5 The results show that this multimode liquid chromatography packing material exhibits excellent separation selectivity for organic acid compounds. The column efficiency for p-hydroxybenzoic acid is 59484.1. Meanwhile, the resolution R = 3.649 for trans-cinnamic acid and benzoic acid, successfully achieving baseline separation.

[0043] Experimental Example 3: Isolation of Alkaloids Preparation of a multimode liquid chromatography column modified with ionic liquid hydrogel: The multimode liquid chromatography packing material prepared in Example 1 was packed into a 150×4.6mm stainless steel liquid chromatography column using a high-pressure homogenization method for the separation and analysis of alkaloids (including piperine, caffeine, theobromine, berberine hydrochloride, and tetrandrine). During packing, both the dispersion and displacement solvent were methanol, and the pressure was 40 MPa.

[0044] Chromatographic separation of alkaloids: The chromatographic analysis conditions were as follows: mobile phase: acetonitrile / 100 mM ammonium acetate (87 / 13, v / v); flow rate: 1.0 mL / min; UV detector: 206 nm; injection volume: 20 µL.

[0045] like Figure 6 The diagram shows the separation of alkaloids using the ion-liquid-modified silica gel multimode liquid chromatography column prepared in Example 1 of this invention, under the mobile phase of acetonitrile / 100 mM ammonium acetate (87 / 13, v / v); peak 1 is piperine; peak 2 is caffeine; peak 3 is theobromine; peak 4 is berberine hydrochloride; and peak 5 is tetrandrine. Figure 6 The results show that this multimode liquid chromatography packing material exhibits excellent separation selectivity for alkaloids. The column efficiency for caffeine is 16012.1. Furthermore, the resolution R = 3.315 for piperine and caffeine, successfully achieving baseline separation.

[0046] Experimental Example 4: Separation of Aniline Compounds Preparation of a multimode liquid chromatography column modified with ionic liquid hydrogel: The multimode liquid chromatography packing material prepared in Example 1 was packed into a 150×4.6 mm stainless steel liquid chromatography column using a high-pressure homogenization method for the separation and analysis of aniline compounds (including methylformylaniline, 2-fluoroaniline, 2,6-diisopropylaniline, and N,N'-diethylaniline). During packing, both the dispersion and displacement solvent were methanol, and the pressure was 40 MPa.

[0047] Chromatographic separation of aniline compounds: The chromatographic analysis conditions were as follows: mobile phase: acetonitrile / water (14 / 86, v / v); flow rate: 1.0 mL / min; UV detector: 249 nm; injection volume: 20 µL.

[0048] like Figure 7 The diagram shows the separation of aniline compounds using the ionic liquid-modified silica gel multimode liquid chromatography column prepared in Example 1 of this invention under the mobile phase of acetonitrile / water (10 / 90, v / v); peak 1 is methylformylaniline; peak 2 is 2-fluoroaniline; peak 3 is 2,6-diisopropylaniline; and peak 4 is N,N'-diethylaniline. Figure 7 The results show that this multimode liquid chromatography packing material exhibits excellent separation selectivity for aniline compounds. The column efficiency for 2-fluoroaniline is 10620.8. Furthermore, the resolution R = 2.060 between aniline and 2-fluoroaniline successfully achieved baseline separation.

[0049] Experimental Example 5: Separation of Anions Preparation of a multimode liquid chromatography column modified with ionic liquid hydrogel: The multimode liquid chromatography packing material prepared in Example 1 was packed into a 150×4.6mm stainless steel liquid chromatography column using a high-pressure homogenization method for anion exchange (containing SCN). - NO3 - NO2 - and Br - Separation analysis was performed. During the filling process, both the dispersion and the displacement liquid were methanol, and the pressure was 40 MPa.

[0050] Chromatographic separation of anions: The chromatographic analysis conditions were as follows: mobile phase: acetonitrile / 20 mM sodium chloride (85 / 15, v / v); flow rate: 1.0 mL / min; UV detector: 210 nm; injection volume: 20 µL.

[0051] like Figure 8 This is a schematic diagram illustrating the separation of anions using the ion-liquid-modified silica gel multimode liquid chromatography column prepared in Example 1 of this invention, under the mobile phase of acetonitrile / 20 mM sodium chloride (85 / 15, v / v); peak 1 represents SCN. - Peak 2 is NO3.- ; peak 3 is NO2 - ; peak 4 is Br - . From Figure 8 , it can be seen that the multi-modal liquid chromatography packing has good separation selectivity for anions. The column efficiency of NO3 - is 20138.6. At the same time, the resolution R of NO3 - and NO2 - is 3.602, and baseline separation is successfully achieved.

[0052] Experimental Example 6 Comparison of separation of antibiotics by liquid chromatography packing obtained by modifying silica gel with different numbers of monomers The synthesis methods of Example 1, Comparative Example 1 and Comparative Example 2 were used. Three batches of liquid chromatography packing obtained from Example 1, liquid chromatography packing obtained from one monomer modified silica gel of Comparative Example 1 and liquid chromatography packing obtained from two monomers modified silica gel of Comparative Example 2 were synthesized. The three kinds of liquid chromatography packing were loaded into 150x4.6 mm size stainless steel liquid chromatography columns by high pressure homogenization method, and used for separation and analysis of antibiotics (including ornidazole, metronidazole, cefalexin, cefpirome sulfate and ceftriaxone sodium). During the loading process, the dispersion liquid and the displacement liquid were both methanol, and the pressure was 40 MPa.

[0053] Chromatographic separation of antibiotics: the chromatographic analysis conditions were as follows: the mobile phase was acetonitrile / 100 mM ammonium acetate (60 / 40, v / v); the flow rate was 1.0 mL / min; the ultraviolet detector was at 254 nm; and the injection amount was 20 µL.

[0054] As shown in Figure 9 , the comparison chart of separation of antibiotics by the chromatographic column of the ionic liquid hydrogel modified silica gel prepared in Example 1, the chromatographic column of one monomer modified silica gel (Comparative Example 1) and the chromatographic column of two monomers modified silica gel (Comparative Example 2) under the condition that the mobile phase was acetonitrile / 100 mM ammonium acetate (60 / 40, v / v); peak 1 was ornidazole; peak 2 was metronidazole; peak 3 was cefalexin; peak 4 was cefpirome sulfate; and peak 5 was ceftriaxone sodium. From Figure 9 , it can be seen that the liquid chromatography packing obtained from Example 1 successfully separated the five kinds of antibiotics, while the liquid chromatography packing obtained from one monomer modified silica gel and the liquid chromatography packing obtained from two monomers modified silica gel had weak retention for antibiotics and could not effectively separate the five kinds of antibiotics. This phenomenon shows that Example 1, i.e., three monomers modified silica gel, can better achieve chromatographic separation in ion exchange chromatography separation mode.

[0055] Experimental Example 7 Comparison of separation of anions by liquid chromatography packing obtained by modifying silica gel with different numbers of monomers The synthesis methods of Example 1, Comparative Example 1, and Comparative Example 2 were used. The liquid chromatography packing material obtained in Example 1, the liquid chromatography packing material obtained from silica gel modified with one monomer in Comparative Example 1, and the liquid chromatography packing material obtained from silica gel modified with two monomers in Comparative Example 2 were synthesized in three batches. The three liquid chromatography packing materials were packed into 150×4.6mm stainless steel liquid chromatography columns using a high-pressure homogenization method for anion exchange (containing SCN) chromatography. - NO3 - NO2 - and Br - Separation analysis was performed. During the filling process, both the dispersion and the displacement liquid were methanol, and the pressure was 40 MPa.

[0056] Chromatographic separation of anions: The chromatographic analysis conditions were as follows: mobile phase: acetonitrile / 20 mM sodium chloride (85 / 15, v / v); flow rate: 1.0 mL / min; UV detector: 210 nm; injection volume: 20 µL.

[0057] like Figure 10 The image shows a comparison of the separation of anions using a chromatographic column modified with ionic liquid hydrogel prepared in Example 1 of this invention, a chromatographic column modified with one monomer (Comparative Example 1), and a chromatographic column modified with two monomers (Comparative Example 2) under the condition of acetonitrile / 20 mM sodium chloride (85 / 15, v / v); peak 1 represents SCN. - Peak 2 is NO3. - Peak 3 is NO2 - Peak 4 is Br - .from Figure 10 As can be seen from Example 1, the liquid chromatography packing material successfully separated four anions, while the liquid chromatography packing material obtained with one monomer-modified silica gel and the liquid chromatography packing material obtained with two monomer-modified silica gels showed weak retention of anions and could not achieve effective separation of the four anions. This phenomenon is evident in Example 1, where the silica gel with three monomer-modified silica gels is more capable of achieving chromatographic separation in ion exchange chromatography mode.

[0058] In summary, the packing material prepared by this invention can be used for the separation and analysis of compounds of different polarities, including nucleosides / bases, organic acids, alkaloids, aniline compounds, and anions. It enables multi-mode separation and analysis of compounds with different polarities (hydrophilic chromatography, hydrophobic chromatography, and ion exchange chromatography). The separation effect is significantly improved compared to liquid chromatography packing materials modified with one or two monomers on silica gel. Furthermore, the preparation method provided by this invention is simple to operate, and the prepared packing material has great development potential and application prospects in the field of chromatographic separation and analysis.

[0059] Experimental Example 8: Characterization of the liquid chromatography packing materials prepared in Example 1 and Comparative Example 3 The liquid chromatography packing materials prepared in Example 1 and Comparative Example 3 were characterized by SEM, infrared analysis and thermogravimetric analysis. The specific process of SEM characterization was as follows: the synthesized material was dispersed in anhydrous ethanol and its morphology was observed at different magnifications. The specific process of infrared analysis was as follows: the vibration of the synthesized material was observed at different frequencies. The thermogravimetric analysis process was as follows: the temperature was gradually increased from room temperature to 800℃ and the weight loss of the synthesized material at different temperatures was observed.

[0060] like Figure 1 The image shows SEM images of the ionic liquid hydrogel-modified silica gel and bare silica gel prepared in Example 1 of this invention. Image a represents the bare silica gel prepared in Comparative Example 3, and image b represents the filler prepared in Example 1. Figure 1 As can be seen, unlike the smooth bare silicone surface of Comparative Example 3, the rough surface of the filler prepared in Example 1 proves that the silicone surface was successfully coated with ionic liquid hydrogel.

[0061] like Figure 2 The image shows the FT-IR spectra of the ionic liquid hydrogel-modified silica gel and bare silica gel prepared in Example 1 of this invention. The lower line represents the bare silica gel prepared in Comparative Example 3, and the upper line represents the filler prepared in Example 1. Figure 2 It can be seen that the -SiO-H- on the silicone surface is at 3455cm. -1 and 801cm -1 Vibrational peak at 1096 cm⁻¹; -Si-O-Si- at ​​1096 cm⁻¹ -1 The vibration peaks at each location gradually decreased. This demonstrates that the silicone surface of Example 1 was successfully coated with the ionic liquid hydrogel.

[0062] like Figure 3 The figure shows thermogravimetric analyses of the ionic liquid hydrogel-modified silica gel and bare silica gel prepared in Example 1 of this invention. The upper line represents the bare silica gel prepared in Comparative Example 3, and the lower line represents the filler prepared in Example 1. Figure 3 It can be seen that the weight losses of the bare silicone and the prepared filler were 6.81 wt% and 21.37 wt%, respectively, proving that the silicone surface of Example 1 was successfully coated with ionic liquid hydrogel.

[0063] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a multimode liquid chromatography packing material for ionic liquid hydrogel-modified silica gel, characterized in that, The method includes: (1) Dissolve the ionic liquid hydrogel monomer and crosslinking agent fully in a polar aprotic organic solvent to obtain an ionic liquid hydrogel prepolymer solution; The ionic liquid hydrogel monomer is any one or more of 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazolium bromide; (2) Add silica gel to the ionic liquid hydrogel prepolymer solution, sonicate, and let stand; (3) Add the initiator and stir. Under an inert atmosphere at 70℃~80℃, reflux and stir to react. (4) After the reaction is complete, the product is dried under stirring to obtain a solid product. It is washed by centrifugation with deionized water and anhydrous ethanol respectively, and dried to obtain a multimode liquid chromatography packing material prepared by modifying the silica gel surface with ionic liquid hydrogel.

2. The method according to claim 1, characterized in that, In step (1), the polar aprotic organic solvent is dimethyl sulfoxide, the crosslinking agent is N,N'-methylenebisacrylamide, and the mass ratio of the ionic liquid hydrogel monomer to the crosslinking agent is (15~20):

1.

3. The method according to claim 1, characterized in that, In step (1), the ionic liquid hydrogel monomers are 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazolium bromide.

4. The method according to claim 3, characterized in that, The mass ratio of 4-vinylphenylboronic acid, 1-vinyl-2-pyrrolidone and 1-vinyl-3-butylimidazolium bromide is 5:4:(15~20).

5. The method according to claim 1, characterized in that, In step (2), the mass ratio of the silica gel and the ionic liquid hydrogel monomer is (1~4):

1.

6. The method according to claim 1, characterized in that, In step (3), the initiator is selected from any one of azobisisobutyronitrile, ammonium persulfate, hydrogen peroxide and dichloride peroxide.

7. The method according to claim 1, characterized in that, In step (3), the mass ratio of the initiator to the silica gel is 1:(35~40); the stirring speed is 150 rpm~300 rpm.

8. The method according to claim 1, characterized in that, In step (4), the drying temperature is 120℃~140℃ and the drying temperature is 85℃~95℃.

9. A multimode liquid chromatography packing material prepared by the method according to any one of claims 1 to 8.

10. The application of the multimode liquid chromatography packing material as described in claim 9 in the field of chromatographic separation.

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