A modified silica chromatographic microsphere and its preparation method

Abstract

This invention discloses a modified silica chromatographic microsphere and its preparation method, relating to the field of chromatographic packing technology. In preparing the modified silica chromatographic microspheres, the invention first obtains monodisperse silica using a sol-gel method; then, the monodisperse silica is used as a template agent for template dissolution-induced redeposition to obtain primary mesoporous core-shell silica; the primary mesoporous core-shell silica is then used as a composite template agent for template dissolution-induced redeposition again to obtain secondary mesoporous core-shell silica; the secondary mesoporous core-shell silica is surface-modified with γ-aminopropyltriethoxysilane to obtain amino-modified silica; and the amino-modified silica is reacted with dehydroabietic acid, ethyl isocyanate, and an aldehyde functional monomer to obtain the modified silica chromatographic microspheres. The modified silica chromatographic microspheres prepared by this invention have the advantages of large specific surface area, good shell stability, and high column efficiency.

Description

Technical Field

[0001] This invention relates to the field of chromatographic packing technology, specifically to a modified silica chromatographic microsphere and its preparation method. Background Technology

[0002] High-performance liquid chromatography (HPLC) is a crucial tool for the separation and analysis of complex sample systems. Combining powerful separation capabilities with qualitative and quantitative analysis, HPLC has found widespread application in pharmaceuticals, biomedicine, food, and environmental analysis. Currently, the demand for high-throughput separation analysis is constantly growing, requiring further reductions in the analysis time of analytes. Meanwhile, research fields such as genomics, proteomics, and metabolomics require processing complex systems such as biological samples, necessitating higher separation efficiency to meet the requirements of rapid separation and analysis of complex samples. To improve the separation performance of HPLC, ultra-high-performance liquid chromatography (UHPLC) has emerged. UHPLC instruments feature further reduced tubing inner diameters and minimized tubing length, thus minimizing extra-column volume. The pressure resistance of the instrument has also been significantly improved, allowing normal operation at 1500 bar. The development of UHPLC instruments allows for the use of smaller particle size chromatographic packing materials, significantly enhancing the analytical capabilities of HPLC. Sub-2μm porous silica microspheres with particle sizes of 1.5-2μm are already being used as chromatographic column packing materials for UHPLC separation and analysis. However, with smaller particle size, the column pressure increases significantly. Under ultra-high column back pressure operating conditions, a significant frictional heat effect will be generated between the mobile phase and the stationary phase, forming a radial temperature gradient in the column bed, resulting in thermal diffusion, which will lead to chromatographic peak broadening and reduced column efficiency.

[0003] To avoid the high column back pressure generated by small-particle-size fully porous silica microspheres, silica core-shell packing materials have attracted widespread attention. Methods for preparing such core-shell microspheres include self-assembly, template methods, template dissolution-induced redeposition, and polymerization-induced redeposition. However, the self-assembly method is cumbersome, generally requiring 10-15 cycles to achieve the desired particle size, resulting in low yield and high cost. Template methods and template dissolution-induced redeposition share a common problem: the pore size of the surface shell is small, less than 5-8 nm, usually requiring secondary pore expansion for macromolecular separation and analysis. Furthermore, the small pore size and high pore density lead to thin pore walls and poor strength, making the shell prone to detachment during high-pressure testing, thus reducing column efficiency. While polymerization-induced redeposition produces larger pores, the resulting micropores are parallel to the microsphere surface, increasing the diffusion path and reducing column efficiency. Additionally, the microspheres prepared by this method have a wide particle size distribution, requiring further particle size fractionation before application in chromatographic analysis.

[0004] Furthermore, conventional silica microspheres are only surface modified with long-chain chlorosilanes, which is insufficient in functionality and difficult to apply to applications such as the separation of chiral products. Summary of the Invention

[0005] The purpose of this invention is to provide a modified silica chromatographic microsphere and its preparation method, so as to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A modified silica chromatographic microsphere is prepared by reacting amino-modified silica with dehydroabietic acid, ethyl isocyanate, and aldehyde functional monomers.

[0008] The amino-modified silica is prepared by surface modification of secondary mesoporous core-shell silica with γ-aminopropyltriethoxysilane.

[0009] The secondary mesoporous core-shell silica is prepared by re-depositing primary mesoporous core-shell silica using a composite template agent through template dissolution and induction.

[0010] The primary mesoporous core-shell silica is prepared by template dissolution-induced redeposition of monodisperse silica using octadecyltrimethylammonium chloride as a template agent.

[0011] The monodisperse silica was prepared by the sol-gel method.

[0012] As an optimization, the composite template agent includes hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate.

[0013] As an optimization, the aldehyde functional monomer contains a hydrophobic carbon chain or a dichlorobenzene structure.

[0014] As an optimization, the aldehyde functional monomer is one or more of the following: pentanal, hexanal, heptanal, octanal, nonanal, decanal, undecanoal, dodecanal, 3-[(2,4-dichlorobenzyl)oxy]benzaldehyde, 5-(2,4-dichlorophenyl)furfural, 4-[(2,4-dichlorophenyl)methoxy]benzaldehyde, and 3,5-dichlorobenzaldehyde.

[0015] A method for preparing modified silica chromatographic microspheres includes the following preparation steps:

[0016] (1) First, add octadecyltrimethylammonium chloride to water and stir at 35~45℃ until completely dissolved. Add monodisperse silica and sonicate at 35~45℃ for 20~30 min. Then add ammonia and n-tetradecane. Stir at 100~200 r / min for 10~15 min and sonicate for 8~10 min. Add pre-dissolved ammonium fluoride and reflux at 85~90℃ and 100~200 r / min for 22~24 h. After cooling, centrifuge at 2500~3000 rpm to remove the liquid. First, centrifuge with pure water until neutral, then centrifuge with anhydrous ethanol 2~3 times. Dry at 60~70℃ and calcine at 600~650℃ for 8~10℃ / min for 8~10 h. Cool naturally to room temperature to obtain primary mesoporous core-shell silica.

[0017] (2) First, dissolve hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride and sodium dodecyl sulfonate in pure water and mix them. Stir at 35-45℃ and 100-200r / min for 10-15min. Add primary mesoporous core-shell silica and ultrasonically disperse at 35-45℃ for 20-30min. Then add ammonia and n-tetradecane. Stir at 100-200r / min for 10-15min and ultrasonically for 8-10min. Add pre-dissolved sodium carbonate and reflux at 85-95℃ and 100-200r / min for 10-12h. After cooling, centrifuge at 2500-3000rpm. First, wash with pure water until neutral, then wash with anhydrous ethanol 2-3 times. Dry at 60-70℃ and calcine at 600-650℃ for 5-6h with a temperature increase of 4-5℃ / min. Cool naturally to room temperature to obtain secondary mesoporous core-shell silica.

[0018] (3) First, soak and wash the secondary mesoporous core-shell silica in pure water for 50-60 min, then dry it at 60-70℃, then mix it with γ-aminopropyltriethoxysilane and anhydrous toluene, sonicate it at room temperature for 15-20 min, reflux it at 110-120℃ and 150-200 r / min for 20-24 h, cool it and centrifuge to remove the liquid, wash it with toluene, anhydrous ethanol and pure water in sequence, and vacuum dry it at 60-70℃ for 10-12 h to obtain amino-modified silica;

[0019] (4) Mix amino-modified silica, dehydroabietic acid, ethyl isocyanate, aldehyde functional monomer and solvent evenly, seal, sonicate at room temperature for 8-10 min, then stir at room temperature for 200-300 r / min for 12-14 h, centrifuge to remove liquid, wash with anhydrous ethanol and pure water 2-3 times in sequence, and vacuum dry at 60-70℃ for 10-12 h to obtain modified silica chromatographic microspheres.

[0020] As an optimization, the preparation method of monodisperse silica in step (1) is as follows: according to the mass ratio of tetraethyl orthosilicate, potassium chloride, pure water, ammonia, and anhydrous ethanol of 1:(0.004~0.005):(1.6~1.8):(0.8~1):(25~30), first mix potassium chloride, pure water, ammonia, and anhydrous ethanol evenly, stir at room temperature for 20~30 min, then add tetraethyl orthosilicate solution dropwise at a rate of 0.5~0.6 ml / min, stir the reaction at room temperature for 3~4 h after the addition is completed, centrifuge to remove the liquid, wash, dry, and obtain monodisperse silica.

[0021] As an optimization, the preparation method of monodisperse silica in step (1) is as follows: the mass ratio of tetraethyl orthosilicate, potassium chloride, pure water, ammonia, and anhydrous ethanol is 1:(0.004~0.005):(1.6~1.8):(0.8~1):(25~30). First, the potassium chloride, pure water, ammonia, and anhydrous ethanol are mixed evenly and stirred at 200~300 r / min for 20~30 min at room temperature. Then, tetraethyl orthosilicate solution is added dropwise at a rate of 0.5~0.6 ml / min. After the addition is completed, the mixture is stirred at 200~300 r / min for 3~4 h at room temperature. The liquid is removed by centrifugation, and the mixture is washed 2~3 times by centrifugation with anhydrous ethanol. The mixture is then vacuum dried at 60~70℃ for 10~12 h to obtain monodisperse silica.

[0022] As an optimization, the tetraethyl orthosilicate solution is a 30wt% tetraethyl orthosilicate ethanol solution.

[0023] As an optimization, the mass ratio of monodisperse silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, ammonium fluoride, and pure water in step (1) is 1:(0.72~0.76):(5.6~6):(1.5~1.6):(0.025~0.027):(85~95).

[0024] As an optimization, the mass fraction of the ammonia water is 25%.

[0025] As an optimization, the mass ratio of the primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water in step (2) is 1:(0.58~0.62):(0.14~0.15):(0.03~0.035):(2.5~3):(0.7~0.8):(0.06~0.07):(70~80).

[0026] As an optimization, the mass ratio of the secondary mesoporous core-shell silica, γ-aminopropyltriethoxysilane, and anhydrous toluene in step (3) is 1:(3.5~4):(50~60).

[0027] As an optimization, the molar ratio of amino groups, dehydroabsic acid, ethyl isocyanate, and aldehyde functional monomers on the surface of the amino-modified silica in step (4) is 1:(1~1.2):(1~1.1):(1~1.1), and the mass ratio of amino-modified silica to solvent is 1:(50~60).

[0028] As an optimization, the solvent in step (4) is one of methanol, N,N-dimethylformamide, and tetrahydrofuran.

[0029] As an optimization, the reaction process of the modified silica chromatographic microspheres in step (4) is as follows:

[0030] ;

[0031] R includes the following structures:

[0032] ;

[0033] n is an integer greater than 3.

[0034] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0035] In preparing modified silica chromatographic microspheres, this invention first uses a sol-gel method to obtain monodisperse silica; then, the monodisperse silica is used as a template agent to induce template dissolution and redeposition, resulting in primary mesoporous core-shell silica; the primary mesoporous core-shell silica is then used as a composite template agent to induce template dissolution and redeposition again, resulting in secondary mesoporous core-shell silica; the secondary mesoporous core-shell silica is then surface-modified with γ-aminopropyltriethoxysilane to obtain amino-modified silica; finally, the amino-modified silica is reacted with dehydroabietic acid, ethyl isocyanate, and an aldehyde functional monomer to obtain modified silica chromatographic microspheres.

[0036] First, monodisperse silica was prepared using an improved sol-gel method. The particle size of the monodisperse silica was 2.5~3μm, and it was a non-porous silica microsphere. By controlling the amount of potassium chloride electrolyte added, the particle size of the prepared microspheres could be significantly increased to the micrometer level, so that it met the particle size requirements of high performance liquid chromatography packing. Subsequently, ammonium fluoride was used as an etchant and octadecyltrimethylammonium chloride as a template agent to induce redeposition of monodisperse silica. Octadecyltrimethylammonium chloride formed micelles that were adsorbed onto the surface of silica microspheres. After the ammonium fluoride etched the silica, silicate ions were released. These silicate ions were then captured by the template agent micelles adsorbed on the surface of the silica microspheres and redeposited on the surface of the silica microspheres. This cycle was repeated to form a shell layer with a large number of mesopores on the surface of the silica core layer. The template agent was then removed by calcination and the silica shell layer was solidified, giving the shell layer a certain mechanical strength. However, the densely distributed small-diameter mesopores made the pore walls thin and the mechanical strength poor, making it easy to fall off and fail during high-pressure testing.

[0037] Secondly, secondary mesoporous core-shell silica was prepared by template dissolution-induced redeposition using a composite template agent. A composite template agent composed of hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate was used. Hexadecyltrimethylammonium chloride served as the main component, trioctylmethylammonium chloride expanded the volume, and sodium dodecyl sulfonate acted as an anionic surfactant. The small amount added avoided precipitation while further reducing the critical micelle concentration and increasing the micelle volume. Furthermore, sodium carbonate was used as the etchant for the secondary template dissolution-induced redeposition. The second template dissolution-induced redeposition continued on the channels formed in the first stage. Using the template formed in the first stage, the etching rate of sodium carbonate was slower and gentler, avoiding excessive damage to the channels formed in the first deposition. Subsequently, the larger volume of template agent occupied the channels, and the etching action of sodium carbonate merged the densely packed small channels, resulting in thicker pore walls to improve mechanical strength. Although the specific surface area decreased, it could better perform its function under high pressure environments, avoiding performance failure caused by shell detachment.

[0038] Finally, amino-modified silica was prepared by surface modification of secondary mesoporous core-shell silica with γ-aminopropyltriethoxysilane; modified silica chromatographic microspheres were prepared by reacting amino-modified silica with dehydroabietic acid, ethyl isocyanate and aldehyde functional monomer. The modification of γ-aminopropyltriethoxysilane first involves covering the hydroxyl groups on the silica surface to reduce its surface polarity, making it partially hydrophobic. Amino reactive groups are then introduced onto the silica surface. Subsequently, through a Ugi multicomponent reaction, the amino groups react with the carboxyl groups in dehydroabietic acid, the isocyanate groups in ethyl isocyanate, and the aldehyde groups in the aldehyde functional monomer to form a stable α-acylaminoamide structure. Simultaneously, a hydrophobic rigid ring structure on the dehydroabietic acid and a hydrophobic carbon chain or a dichlorobenzene structure with chiral separation function are introduced from the aldehyde functional monomer. The large-area rigid ring of dehydroabietic acid is fixed on the surface and channels of the secondary mesoporous core-shell silica, acting like a tennis racket to intercept and adsorb small molecules in the mixture. Different molecules have different residence times, thus separating them and producing clear peak shapes. The improved hydrophobicity also effectively improves column efficiency. Furthermore, other functional monomers can be introduced to the aldehyde functional monomer position to achieve different functionalities, demonstrating good re-modification capabilities. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] The raw material information used in all the following examples and comparative examples is as follows:

[0041] Monodisperse silica: The mass ratio of tetraethyl orthosilicate, potassium chloride, pure water, ammonia, and anhydrous ethanol was 1:0.0045:1.7:0.9:28. First, potassium chloride, pure water, ammonia, and anhydrous ethanol were mixed evenly and stirred at 250 rpm for 25 min at room temperature. Then, a 30 wt% tetraethyl orthosilicate-ethanol solution was added dropwise at a rate of 0.55 ml / min. After the addition was complete, the mixture was stirred at 250 rpm for 3.5 h at room temperature. The liquid was removed by centrifugation, and the mixture was washed twice with anhydrous ethanol by centrifugation. Finally, it was vacuum dried at 65 °C for 11 h to obtain monodisperse silica with an average particle size of 2.89 μm and a polydispersity index of 3.87%.

[0042] Ammonia solution: mass fraction 25%;

[0043] Ammonium fluoride: Pre-dissolved into an aqueous solution of ammonium fluoride with a concentration of 10 mg / ml;

[0044] Sodium carbonate: Pre-dissolved into a 10wt% sodium carbonate aqueous solution.

[0045] In all the following examples and comparative examples, the primary mesoporous core-shell silica was first soaked and cleaned in pure water for 55 minutes before use, and then dried at 65°C.

[0046] Example 1:

[0047] A method for preparing modified silica chromatographic microspheres, the method comprising the following preparation steps:

[0048] (1) The mass ratio of monodisperse silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, ammonium fluoride and pure water is 1:0.72:5.6:1.5:0.025:85. First, add octadecyltrimethylammonium chloride to water and stir at 35°C until completely dissolved. Then add monodisperse silica and sonicate at 35°C for 30 min. Then add ammonia and n-tetradecane. Stir at 100 r / min for 15 min and sonicate for 8 min. Add pre-dissolved ammonium fluoride. Connect a balloon to the condenser and reflux at 85°C and 100 r / min for 24 h. After cooling, centrifuge at 2500 rpm to remove the liquid. First, centrifuge and wash with pure water until neutral. Then centrifuge and wash twice with anhydrous ethanol. Dry at 60°C and calcine at 600°C for 10 h by heating at 8°C / min. Then cool naturally to room temperature to obtain primary mesoporous core-shell silica.

[0049] (2) The mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.58:0.14:0.03:2.5:0.7:0.06:70. First, dissolve hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate separately in pure water and then mix them. Stir at 35°C and 100 r / min for 15 min. Then add primary mesoporous core-shell silica and stir at 35°C. The mixture was ultrasonically dispersed for 30 min, then ammonia and n-tetradecane were added. The mixture was stirred at 100 r / min for 15 min, then ultrasonicated for 8 min. Pre-dissolved sodium carbonate was added, and a balloon was attached to the condenser. The mixture was refluxed at 85℃ and 100 r / min for 12 h. After cooling, the mixture was centrifuged at 2500 rpm. It was first washed with pure water until neutral, then washed twice with anhydrous ethanol. It was dried at 60℃ and calcined at 600℃ for 6 h by heating at 4℃ / min. After naturally cooling to room temperature, secondary mesoporous core-shell silica was obtained.

[0050] (3) The secondary mesoporous core-shell silica, γ-aminopropyltriethoxysilane and anhydrous toluene were mixed in a mass ratio of 1:3.5:50. The secondary mesoporous core-shell silica was first soaked and washed in pure water for 50 min, then dried at 60℃, and then mixed with γ-aminopropyltriethoxysilane and anhydrous toluene. The mixture was sonicated at room temperature for 15 min, and then refluxed at 110℃ and 150 r / min for 24 h. After cooling, the liquid was removed by centrifugation, and the silica was washed successively with toluene, anhydrous ethanol and pure water by centrifugation. The silica was then vacuum dried at 60℃ for 12 h to obtain amino-modified silica.

[0051] (4) The amino-modified silica surface amino group, dehydroabietic acid, ethyl isocyanate, and n-hexanal were mixed evenly according to the molar ratio of amino group, dehydroabietic acid, ethyl isocyanate, n-hexanal, and n-dimethylformamide of 1:1:1:1 and the mass ratio of amino-modified silica and N,N-dimethylformamide of 1:50. The mixture was sealed and sonicated at room temperature for 8 min. Then, it was stirred at room temperature at 200 r / min for 14 h. The liquid was removed by centrifugation and washed twice with anhydrous ethanol and pure water by centrifugation. The mixture was then dried under vacuum at 60 °C for 12 h to obtain modified silica chromatographic microspheres.

[0052] Example 2:

[0053] A method for preparing modified silica chromatographic microspheres, the method comprising the following preparation steps:

[0054] (1) The mass ratio of monodisperse silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, ammonium fluoride and pure water is 1:0.74:5.8:1.55:0.026:90. First, add octadecyltrimethylammonium chloride to water and stir at 40°C until completely dissolved. Add monodisperse silica and sonicate at 40°C for 25 min. Then add ammonia and n-tetradecane. Stir at 150 r / min for 12 min and sonicate for 9 min. Add pre-dissolved ammonium fluoride. Connect a balloon to the condenser and reflux at 88°C and 150 r / min for 23 h. After cooling, centrifuge at 2500 rpm to remove the liquid. First, wash with pure water until neutral, then wash twice with anhydrous ethanol. Dry at 65°C and calcine at 625°C for 9 h. Cool naturally to room temperature to obtain primary mesoporous core-shell silica.

[0055] (2) The mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.6:0.145:0.032:2.8:0.75:0.065:75. First, dissolve hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate separately in pure water and then mix them. Stir at 40°C and 150 r / min for 12 min. Then add primary mesoporous core-shell silica and stir at 40°C. The mixture was ultrasonically dispersed for 25 min, then ammonia and n-tetradecane were added. The mixture was stirred at 150 r / min for 12 min, then ultrasonicated for 9 min. Pre-dissolved sodium carbonate was added, and a balloon was attached to the condenser. The mixture was refluxed at 90℃ and 150 r / min for 11 h. After cooling, the mixture was centrifuged at 2500 rpm. It was first washed with pure water until neutral, then washed twice with anhydrous ethanol. It was dried at 65℃ and calcined at 625℃ for 5.5 h by heating at 4.5℃ / min. After naturally cooling to room temperature, secondary mesoporous core-shell silica was obtained.

[0056] (3) The secondary mesoporous core-shell silica, γ-aminopropyltriethoxysilane and anhydrous toluene were in a mass ratio of 1:3.8:55. The secondary mesoporous core-shell silica was first soaked and washed in pure water for 55 min, then dried at 65°C, and then mixed with γ-aminopropyltriethoxysilane and anhydrous toluene. The mixture was sonicated at room temperature for 18 min, and then refluxed at 115°C and 175 r / min for 22 h. After cooling, the liquid was removed by centrifugation, and the silica was washed successively with toluene, anhydrous ethanol and pure water by centrifugation. The silica was then vacuum dried at 65°C for 11 h to obtain amino-modified silica.

[0057] (4) The amino-modified silica surface amino group, dehydroabietic acid, ethyl isocyanate, and n-hexanal were mixed evenly according to the molar ratio of amino group, dehydroabietic acid, ethyl isocyanate, n-hexanal, and n-dimethylformamide as 1:1.1:1.05:1.05, and the mass ratio of amino-modified silica and N,N-dimethylformamide was 1:55. The mixture was sealed and sonicated at room temperature for 9 min. Then, it was stirred at room temperature at 250 r / min for 13 h. The liquid was removed by centrifugation and washed twice with anhydrous ethanol and pure water by centrifugation. The mixture was then dried under vacuum at 65 °C for 11 h to obtain modified silica chromatographic microspheres.

[0058] Example 3:

[0059] A method for preparing modified silica chromatographic microspheres, the method comprising the following preparation steps:

[0060] (1) The mass ratio of monodisperse silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, ammonium fluoride and pure water is 1:0.76:6:1.6:0.027:95. First, add octadecyltrimethylammonium chloride to water and stir at 45°C until completely dissolved. Add monodisperse silica and sonicate at 45°C for 20 min. Then add ammonia and n-tetradecane. Stir at 200 r / min for 10 min and sonicate for 10 min. Add pre-dissolved ammonium fluoride. Connect a balloon to the condenser and reflux at 90°C and 200 r / min for 22 h. After cooling, centrifuge at 3000 rpm to remove the liquid. First, centrifuge and wash with pure water until neutral. Then, centrifuge and wash three times with anhydrous ethanol. Dry at 70°C and calcine at 650°C for 8 h at 10°C / min. Cool naturally to room temperature to obtain primary mesoporous core-shell silica.

[0061] (2) The mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.62:0.15:0.035:3:0.8:0.07:80. First, dissolve hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate separately in pure water and then mix them. Stir at 45°C and 200 r / min for 10 min. Then add primary mesoporous core-shell silica and stir at 45°C. The mixture was dispersed for 20 min, then ammonia and n-tetradecane were added. The mixture was stirred at 200 rpm for 10 min, then sonicated for 10 min. Pre-dissolved sodium carbonate was added, and a balloon was attached to the condenser. The mixture was refluxed at 95 °C and 200 rpm for 10 h. After cooling, the mixture was centrifuged at 3000 rpm. It was first washed with pure water until neutral, then washed three times with anhydrous ethanol. It was dried at 70 °C and calcined at 650 °C for 5 h at a rate of 5 °C / min. After cooling to room temperature, secondary mesoporous core-shell silica was obtained.

[0062] (3) The secondary mesoporous core-shell silica, γ-aminopropyltriethoxysilane and anhydrous toluene were mixed in a mass ratio of 1:4:60. The secondary mesoporous core-shell silica was first soaked and washed in pure water for 60 min, then dried at 70 °C, and then mixed with γ-aminopropyltriethoxysilane and anhydrous toluene. The mixture was sonicated at room temperature for 20 min, and then refluxed at 120 °C and 200 r / min for 20 h. After cooling, the liquid was removed by centrifugation. The silica was washed successively with toluene, anhydrous ethanol and pure water by centrifugation, and then vacuum dried at 70 °C for 10 h to obtain amino-modified silica.

[0063] (4) The amino-modified silica surface amino group, dehydroabietic acid, ethyl isocyanate, and n-hexanal were mixed evenly according to the molar ratio of amino group, dehydroabietic acid, ethyl isocyanate, n-hexanal, and n-dimethylformamide as 1:1.2:1.1:1.1, and the mass ratio of amino-modified silica and N,N-dimethylformamide was 1:60. The mixture was sealed and sonicated at room temperature for 10 min. Then, it was stirred at room temperature at 300 r / min for 12 h. The liquid was removed by centrifugation and washed three times with anhydrous ethanol and pure water. The mixture was then vacuum dried at 70 °C for 10 h to obtain modified silica chromatographic microspheres.

[0064] Example 4:

[0065] A method for preparing modified silica chromatographic microspheres, the method comprising the following preparation steps:

[0066] (1) The mass ratio of monodisperse silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, ammonium fluoride and pure water is 1:0.74:5.8:1.55:0.026:90. First, add octadecyltrimethylammonium chloride to water and stir at 40°C until completely dissolved. Add monodisperse silica and sonicate at 40°C for 25 min. Then add ammonia and n-tetradecane. Stir at 150 r / min for 12 min and sonicate for 9 min. Add pre-dissolved ammonium fluoride. Connect a balloon to the condenser and reflux at 88°C and 150 r / min for 23 h. After cooling, centrifuge at 2500 rpm to remove the liquid. First, wash with pure water until neutral, then wash twice with anhydrous ethanol. Dry at 65°C and calcine at 625°C for 9 h. Cool naturally to room temperature to obtain primary mesoporous core-shell silica.

[0067] (2) The mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.6:0.145:0.032:2.8:0.75:0.065:75. First, dissolve hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate separately in pure water and then mix them. Stir at 40°C and 150 r / min for 12 min. Then add primary mesoporous core-shell silica and stir at 40°C. The mixture was ultrasonically dispersed for 25 min, then ammonia and n-tetradecane were added. The mixture was stirred at 150 r / min for 12 min, then ultrasonicated for 9 min. Pre-dissolved sodium carbonate was added, and a balloon was attached to the condenser. The mixture was refluxed at 90℃ and 150 r / min for 11 h. After cooling, the mixture was centrifuged at 2500 rpm. It was first washed with pure water until neutral, then washed twice with anhydrous ethanol. It was dried at 65℃ and calcined at 625℃ for 5.5 h by heating at 4.5℃ / min. After naturally cooling to room temperature, secondary mesoporous core-shell silica was obtained.

[0068] (3) The secondary mesoporous core-shell silica, γ-aminopropyltriethoxysilane and anhydrous toluene were in a mass ratio of 1:3.8:55. The secondary mesoporous core-shell silica was first soaked and washed in pure water for 55 min, then dried at 65°C, and then mixed with γ-aminopropyltriethoxysilane and anhydrous toluene. The mixture was sonicated at room temperature for 18 min, and then refluxed at 115°C and 175 r / min for 22 h. After cooling, the liquid was removed by centrifugation, and the silica was washed successively with toluene, anhydrous ethanol and pure water by centrifugation. The silica was then vacuum dried at 65°C for 11 h to obtain amino-modified silica.

[0069] (4) The amino-modified silica surface amino group, dehydroabietic acid, ethyl isocyanate, and 3-[(2,4-dichlorobenzyl)oxy]benzaldehyde were mixed evenly according to the molar ratio of amino group, dehydroabietic acid, ethyl isocyanate, and 3-[(2,4-dichlorobenzyl)oxy]benzaldehyde as 1:1.1:1.05:1.05, and the mass ratio of amino-modified silica and N,N-dimethylformamide as 1:55. The mixture was sealed and sonicated at room temperature for 9 min. Then, it was stirred at room temperature at 250 r / min for 13 h. The liquid was removed by centrifugation. The mixture was washed twice by centrifugation with anhydrous ethanol and pure water, and then dried under vacuum at 65 °C for 11 h to obtain modified silica chromatographic microspheres.

[0070] Comparative Example 1:

[0071] The difference between the preparation method of the modified silica chromatographic microspheres in Comparative Example 1 and Example 2 lies in the different step (2). Step (2) is modified as follows: the mass ratio of primary mesoporous core-shell silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.74:2.8:0.75:0.065:75. First, dissolve octadecyltrimethylammonium chloride in pure water, stir at 150 r / min for 12 min at 40°C, add primary mesoporous core-shell silica, and sonicate at 40°C. Disperse for 25 min, then add ammonia and n-tetradecane. Stir at 150 rpm for 12 min, then sonicate for 9 min. Add pre-dissolved sodium carbonate. Attach a balloon to the condenser and reflux at 90°C and 150 rpm for 11 h. After cooling, centrifuge at 2500 rpm. Wash with pure water until neutral, then wash twice with anhydrous ethanol. Dry at 65°C, calcine at 625°C for 5.5 h at a rate of 4.5°C / min, and allow to cool naturally to room temperature to obtain secondary mesoporous core-shell silica. The remaining steps are the same as in Example 2.

[0072] Comparative Example 2:

[0073] The difference between the preparation method of the modified silica chromatographic microspheres in Comparative Example 2 and Example 2 lies in step (2). Step (2) is modified as follows: the mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, ammonium fluoride, and pure water is 1:0.6:0.145:0.032:2.8:0.75:0.013:75. First, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate are dissolved in pure water and then mixed. The mixture is stirred at 40°C and 150 r / min for 12 minutes. Add primary mesoporous core-shell silica and ultrasonically disperse at 40°C for 25 min. Then add ammonia and n-tetradecane, stir at 150 rpm for 12 min, then sonicate for 9 min. Add pre-dissolved ammonium fluoride, attach a balloon to the condenser, and reflux at 90°C and 150 rpm for 11 h. After cooling, centrifuge at 2500 rpm, wash with pure water until neutral, then wash twice with anhydrous ethanol, dry at 65°C, calcine at 625°C for 5.5 h at a rate of 4.5°C / min, and allow to cool naturally to room temperature to obtain secondary mesoporous core-shell silica. The remaining steps are the same as in Example 2.

[0074] Comparative Example 3:

[0075] The difference between the preparation method of the modified silica chromatographic microspheres in Comparative Example 3 and Example 2 lies in the different step (2). Step (2) is modified as follows: the mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.6:0.145:0.032:2.8:0.75:0.065:75. First, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate are dissolved in pure water and then mixed. The mixture is then heated at 40°C and 150 r / min. Stir for 12 min, add primary mesoporous core-shell silica, and ultrasonically disperse at 40℃ for 25 min. Then add ammonia and n-tetradecane, stir at 150 rpm for 12 min, then ultrasonicate for 9 min. Add pre-dissolved sodium carbonate, attach a balloon to the condenser, and reflux at 90℃ and 150 rpm for 11 h. After cooling, centrifuge at 2500 rpm, wash with pure water until neutral, then wash twice with anhydrous ethanol, dry at 65℃, calcine at 625℃ for 9 h at a rate of 9℃ / min, and allow to cool naturally to room temperature to obtain secondary mesoporous core-shell silica. The remaining steps are the same as in Example 2.

[0076] Comparative Example 4:

[0077] The preparation method of the modified silica chromatographic microspheres in Comparative Example 4 differs from that in Example 2 in step (2). Step (2) is modified as follows: the mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.6:0.145:0.096:2.8:0.75:0.065:75. First, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate are dissolved in pure water and then mixed. The mixture is stirred at 40°C and 150 r / min. After 12 minutes, primary mesoporous core-shell silica was added and ultrasonically dispersed at 40°C for 25 minutes. Then, ammonia and n-tetradecane were added, and the mixture was stirred at 150 rpm for 12 minutes, followed by ultrasonication for 9 minutes. Pre-dissolved sodium carbonate was added, and a balloon was attached to the condenser. The mixture was refluxed at 90°C and 150 rpm for 11 hours. After cooling, it was centrifuged at 2500 rpm, washed with pure water until neutral, and then washed twice with anhydrous ethanol. It was dried at 65°C and calcined at 625°C for 5.5 hours at a rate of 4.5°C / min. After natural cooling to room temperature, secondary mesoporous core-shell silica was obtained. The remaining steps were the same as in Example 2.

[0078] Comparative Example 5:

[0079] The difference between the preparation method of the modified silica chromatographic microspheres in Comparative Example 5 and Example 2 lies in the different step (2). Step (2) is modified as follows: the mass ratio of primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water is 1:0.6:0.24:0.032:2.8:0.75:0.065:75. First, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate are dissolved in pure water and then mixed. The mixture is stirred at 40°C and 150 r / min for 1 minute. Add primary mesoporous core-shell silica for 2 minutes, and ultrasonically disperse at 40°C for 25 minutes. Then add ammonia and n-tetradecane, stir at 150 rpm for 12 minutes, and then sonicate for 9 minutes. Add pre-dissolved sodium carbonate, attach a balloon to the condenser, and reflux at 90°C and 150 rpm for 11 hours. After cooling, centrifuge at 2500 rpm, wash with pure water until neutral, and then wash twice with anhydrous ethanol. Dry at 65°C, calcine at 625°C for 5.5 hours at a rate of 4.5°C / min, and allow to cool naturally to room temperature to obtain secondary mesoporous core-shell silica. The remaining steps are the same as in Example 2.

[0080] Comparative Example 6:

[0081] The preparation method of the modified silica chromatographic microspheres in Comparative Example 6 differs from that in Example 2 in that step (2) is omitted, and step (3) is modified as follows: the mass ratio of primary mesoporous core-shell silica, γ-aminopropyltriethoxysilane, and anhydrous toluene is 1:3.8:55. First, the primary mesoporous core-shell silica is soaked and washed in pure water for 55 min, then dried at 65°C, and then mixed with γ-aminopropyltriethoxysilane and anhydrous toluene. The mixture is ultrasonicated at room temperature for 18 min, and then refluxed at 115°C and 175 r / min for 22 h. After cooling, the liquid is removed by centrifugation, and the microspheres are washed successively with toluene, anhydrous ethanol, and pure water by centrifugation. The microspheres are then vacuum dried at 65°C for 11 h to obtain amino-modified silica. The remaining steps are the same as in Example 2.

[0082] Comparative Example 7:

[0083] The preparation method of the modified silica chromatographic microspheres in Comparative Example 7 differs from that in Example 2 in that step (2) is omitted, and step (1) is modified as follows: the mass ratio of monodisperse silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, ammonium fluoride, and pure water is 1:0.6:0.145:0.032:5.8:1.55:0.026:90. First, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate are dissolved in pure water and then mixed. The mixture is stirred at 40°C and 150 r / min. After 12 minutes, monodisperse silica was added and ultrasonically dispersed at 40°C for 25 minutes. Then, ammonia and n-tetradecane were added, and the mixture was stirred at 150 rpm for 12 minutes, followed by ultrasonication for 9 minutes. Pre-dissolved ammonium fluoride was added, and a balloon was attached to the condenser. The mixture was refluxed at 88°C and 150 rpm for 23 hours. After cooling, the liquid was removed by centrifugation at 2500 rpm. The mixture was first washed with pure water until neutral, then washed twice with anhydrous ethanol. It was dried at 65°C and calcined at 625°C at a rate of 9°C / min for 9 hours. After natural cooling to room temperature, primary mesoporous core-shell silica was obtained. The remaining steps were the same as in Example 2.

[0084] Comparative Example 8:

[0085] The preparation method of the modified silica chromatographic microspheres in Comparative Example 8 differs from that in Example 2 in that step (4) is omitted, and step (3) is modified as follows: The secondary mesoporous core-shell silica, octadecyltrichlorosilane, and anhydrous toluene are mixed in a mass ratio of 1:2:55. The secondary mesoporous core-shell silica is first soaked and washed in pure water for 55 min, then dried at 65°C, and then mixed with octadecyltrichlorosilane and anhydrous toluene. The mixture is ultrasonicated at room temperature for 18 min, and then refluxed at 115°C and 175 r / min for 22 h. After cooling, the liquid is removed by centrifugation, and the microspheres are washed sequentially with toluene, anhydrous ethanol, and pure water by centrifugation. The microspheres are then vacuum dried at 65°C for 11 h to obtain the modified silica chromatographic microspheres. The remaining steps are the same as in Example 2.

[0086] Comparative Example 9:

[0087] The preparation method of the modified silica chromatographic microspheres in Comparative Example 9 differs from that in Example 2 in step (4). Step (4) is modified as follows: the molar ratio of amino groups on the surface of amino-modified silica, lauric acid, ethyl isocyanate, and hexanal is 1:1.1:1.05:1.05, and the mass ratio of amino-modified silica to N,N-dimethylformamide is 1:55. The amino-modified silica, lauric acid, ethyl isocyanate, hexanal, and N,N-dimethylformamide are mixed evenly, sealed, and sonicated at room temperature for 9 min. Then, the mixture is stirred at room temperature at 250 r / min for 13 h. The liquid is removed by centrifugation, and the microspheres are washed twice by centrifugation with anhydrous ethanol and pure water, respectively. The microspheres are then dried under vacuum at 65 °C for 11 h to obtain the modified silica chromatographic microspheres. The remaining steps are the same as in Example 2.

[0088] Test Example 1:

[0089] Basic performance testing: The specific surface area and average pore size of the prepared modified silica chromatographic microspheres were tested using a BETA201B specific surface area and pore size analyzer. The specific surface area and average pore size of the modified silica chromatographic microspheres were calculated using the BET method and the BJH method. Each group was tested in parallel for 5 times, and the average value was recorded.

[0090] The results are shown in Table 1.

[0091] Table 1

[0092] ;

[0093] A comparison of the experimental data from Examples 1-4 and Comparative Examples 1-9 in Table 1 reveals that the modified silica chromatographic microspheres prepared in this invention have a good specific surface area and a large pore size.

[0094] By comparing the data in the table, the data in Comparative Example 1 shows that the use of composite template agent in secondary template dissolution-induced redeposition effectively improves the pore-expanding effect.

[0095] By comparing the data in the table, the data in Comparative Example 2 shows that using sodium carbonate instead of ammonium fluoride in secondary template dissolution-induced redeposition can avoid excessive etching of the pore walls, thereby retaining more specific surface area.

[0096] By comparing the data in the table, the data in Comparative Example 3 shows that reducing the calcination heating rate and calcination time in secondary template dissolution-induced redeposition can avoid the specific surface area loss caused by shell pore cracking and shedding.

[0097] By comparing the data in the table, the data in Comparative Example 4 shows that excessive addition of sodium dodecyl sulfonate in the secondary template dissolution-induced redeposition process can lead to micelle flocculation and precipitation, which cannot be formed, resulting in poor secondary modification effect.

[0098] By comparing the data in the table, the data in Comparative Example 5 shows that excessive addition of trioctylmethylammonium chloride in secondary template dissolution-induced redeposition leads to excessive expansion of micelle volume and a significant loss of specific surface area.

[0099] By comparing the data in the table, the data in Comparative Example 6 shows that although the secondary template dissolution-induced redeposition reduced the specific surface area, it effectively expanded the pore size.

[0100] By comparing the data in the table, the data in Comparative Example 7 shows that the pore-expansion effect of directly using the composite template agent in a single template dissolution-induced redeposition process is poor, and the specific surface area is low.

[0101] Test Example 2:

[0102] Packing material performance testing: The theoretical plate number and shell stability of the prepared modified silica chromatographic microspheres were tested to characterize their performance as a liquid chromatography packing material. The specific test methods are as follows:

[0103] Column packing: The prepared modified silica chromatographic microspheres were packed into a 50 mm × 2.1 mm ID stainless steel chromatographic column using a 1:1 volume ratio mixture of isopropanol and methanol as the pressurizing fluid and a column packing machine. The packing pressure was 80 MPa. The packed column was connected to the high-pressure pump of the high-performance liquid chromatograph, and methanol was used as the mobile phase. The column was equilibrated for about 3 hours at a flow rate of 0.1 ml / min until the UV detection baseline was leveled.

[0104] Separation performance testing: The packed chromatographic column was tested on an Acquity UPLC H-class high-performance liquid chromatograph, connected to a UV detector. The mobile phase was a mixture of acetonitrile and pure water (80:20 v / v), the flow rate was 0.2 ml / min, the detection wavelength was 254 nm, the column temperature was 25 ℃, and the injection volume was 0.1 μL. The samples were toluene, ethylbenzene, propylbenzene, butadiene, pentabenzene, and hexylbenzene. The theoretical plate number of hexylbenzene was calculated. Each test was performed in triplicate, and the average value was recorded.

[0105] Shell stability test: An acetonitrile and pure water mixture with a volume ratio of 80:20 was used as the mobile phase. The flow rate was increased to stabilize the column pressure at 100 MPa for 30 min, and then the flow rate was reduced to 0.1 ml / min for 20 min, which constituted one cycle. The cycle was repeated 50 times. Then, the test was repeated according to the separation performance test. The theoretical plate number of hexane was calculated, and the performance retention rate was calculated by combining the theoretical plate number obtained from the separation performance test. Each group was tested in parallel 5 times, and the average value was recorded.

[0106] Chiral separation test: The mobile phase was a mixture of acetonitrile and pure water at a volume ratio of 90:10, the flow rate was 0.1 ml / min, the detection wavelength was 254 nm, the column temperature was 25 ℃, the injection volume was 0.1 μL, and the sample was a 5 mg / ml acetonitrile solution of hesperidin. The resolution was calculated.

[0107] The results are shown in Table 2.

[0108] Table 2

[0109] ;

[0110] A comparison of the experimental data from Examples 1-4 and Comparative Examples 1-9 in Table 2 reveals that the modified silica chromatographic microspheres prepared in this invention possess excellent column efficiency, resolution, shell stability, and the ability to add chiral separation functionality.

[0111] By comparing the data in the table, the data in Example 4 shows that when the aldehyde functional monomer uses a raw material with a dichlorobenzene structure, a chiral separation function can be added to the modified silica chromatographic microspheres.

[0112] By comparing the data in the table, the data in Comparative Examples 1 and 2 show that the use of composite template agent and sodium carbonate in secondary template dissolution-induced redeposition effectively improved the pore-expanding effect and obtained better separation column efficiency and shell stability.

[0113] By comparing the data in the table, the data in Comparative Example 3 shows that reducing the calcination heating rate and calcination time in secondary template dissolution-induced redeposition can avoid the specific surface area loss caused by shell pore cracking and shedding, and further improve the stability of the shell and extend its service life.

[0114] By comparing the data in the table, the data in Comparative Example 4 shows that excessive addition of sodium dodecyl sulfonate in the secondary template dissolution-induced redeposition process can lead to micelle flocculation and precipitation, which cannot be formed, resulting in poor secondary modification effect, poor separation column efficiency, slow separation speed, and poor shell stability.

[0115] By comparing the data in the table, the data in Comparative Example 5 shows that excessive addition of trioctylmethylammonium chloride in secondary template dissolution-induced redeposition leads to excessive expansion of micelle volume, a large loss of specific surface area, resulting in poor separation column efficiency, slow separation speed, and poor shell stability.

[0116] By comparing the data in the table, the data in Comparative Example 6 shows that although the secondary template dissolution-induced redeposition reduced the specific surface area, it effectively expanded the pore size and effectively improved the low separation column efficiency caused by the small pore size.

[0117] By comparing the data in the table, the data in Comparative Example 7 shows that the pore-expansion effect of directly using composite template agent in the first template dissolution-induced redeposition is poor, the specific surface area is low, the column efficiency improvement effect is poor, and the shell stability is not as good as that of the second template dissolution-induced redeposition.

[0118] The data comparison in the table shows that the introduction of aldehyde functional monomers and dehydroabietic acid into the secondary mesoporous core-shell silica surface by the Ugi multicomponent reaction effectively improves the separation performance and column efficiency, and has a better separation effect than octadecyltrichlorosilane.

[0119] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modified silica chromatography microsphere characterized in that, The modified silica chromatographic microspheres are prepared by reacting amino-modified silica with dehydroabietic acid, ethyl isocyanate, and aldehyde functional monomers. The amino-modified silica is prepared by surface modification of secondary mesoporous core-shell silica with γ-aminopropyltriethoxysilane. The secondary mesoporous core-shell silica is prepared by re-depositing primary mesoporous core-shell silica using a composite template agent through template dissolution and induction. The primary mesoporous core-shell silica is prepared by template dissolution-induced redeposition of monodisperse silica using octadecyltrimethylammonium chloride as a template agent. The monodisperse silica was prepared by the sol-gel method; The composite template agent comprises hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate, wherein the mass ratio of hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, and sodium dodecyl sulfonate is (0.58~0.62):(0.14~0.15):(0.03~0.035). Sodium carbonate is used as the etching agent in the preparation of the secondary mesoporous core-shell silica.

2. The modified silica chromatography microsphere of claim 1, wherein, The aldehyde functional monomer contains a hydrophobic carbon chain or a dichlorobenzene structure.

3. The modified silica chromatography microsphere of claim 2, wherein, The aldehyde functional monomer is one or more of the following: pentanal, hexanal, heptanal, octanal, nonanal, decanal, undecanal, dodecanal, 3-[(2,4-dichlorobenzyl)oxy]benzaldehyde, 5-(2,4-dichlorophenyl)furfural, 4-[(2,4-dichlorophenyl)methoxy]benzaldehyde, and 3,5-dichlorobenzaldehyde.

4. A method for preparing the modified silica chromatography microspheres according to any one of claims 1 to 3, characterized in that, The preparation steps include the following: (1) First, add octadecyltrimethylammonium chloride to water and stir until completely dissolved. Add monodisperse silica and ultrasonically disperse it. Then add ammonia and n-tetradecane, stir, ultrasonicate again, add pre-dissolved ammonium fluoride, reflux reaction, cool and centrifuge to remove liquid, wash, dry, calcine, cool to obtain primary mesoporous core-shell silica. (2) First, dissolve hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride and sodium dodecyl sulfonate in pure water and mix them. Stir, add primary mesoporous core-shell silica, and disperse by ultrasonication. Then add ammonia and n-tetradecane, stir first, then sonicate, add pre-dissolved sodium carbonate, reflux reaction, cool, centrifuge to remove liquid, wash, dry, calcine, cool, and obtain secondary mesoporous core-shell silica. (3) First, the secondary mesoporous core-shell silica was soaked and washed in pure water, dried, and then mixed with γ-aminopropyltriethoxysilane and anhydrous toluene. The mixture was sonicated at room temperature and refluxed. After cooling, the liquid was removed by centrifugation, washed, and dried to obtain amino-modified silica. (4) Mix amino-modified silica, dehydroabietic acid, ethyl isocyanate, aldehyde functional monomer and solvent evenly, seal, sonicate at room temperature, stir at room temperature, centrifuge to remove liquid, wash, dry, and obtain modified silica chromatographic microspheres.

5. The method for preparing modified silica chromatographic microspheres according to claim 4, characterized in that, The preparation method of monodisperse silica in step (1) is as follows: according to the mass ratio of tetraethyl orthosilicate, potassium chloride, pure water, ammonia water and anhydrous ethanol of 1:(0.004~0.005):(1.6~1.8):(0.8~1):(25~30), first mix potassium chloride, pure water, ammonia water and anhydrous ethanol evenly, stir at room temperature for 20~30min, then add tetraethyl orthosilicate solution dropwise at a rate of 0.5~0.6ml / min, after the addition is completed, stir the reaction at room temperature for 3~4h, centrifuge to remove liquid, wash, dry, and obtain monodisperse silica.

6. The method for preparing modified silica chromatographic microspheres according to claim 4, characterized in that, The mass ratio of monodisperse silica, octadecyltrimethylammonium chloride, ammonia, n-tetradecane, ammonium fluoride, and pure water in step (1) is 1:(0.72~0.76):(5.6~6):(1.5~1.6):(0.025~0.027):(85~95); The reflux reaction is carried out at a temperature of 85~90℃ for a duration of 22~24h. The calcination heating rate is 8~10℃ / min, the calcination temperature is 600~650℃, and the duration is 8~10h.

7. The method for preparing modified silica chromatographic microspheres according to claim 4, characterized in that, The mass ratio of the primary mesoporous core-shell silica, hexadecyltrimethylammonium chloride, trioctylmethylammonium chloride, sodium dodecyl sulfonate, ammonia, n-tetradecane, sodium carbonate, and pure water in step (2) is 1:(0.58~0.62):(0.14~0.15):(0.03~0.035):(2.5~3):(0.7~0.8):(0.06~0.07):(70~80); The reflux reaction is carried out at a temperature of 85~95℃ for a duration of 10~12h. The calcination heating rate is 4~5℃ / min, the calcination temperature is 600~650℃, and the duration is 5~6h.

8. The method for preparing modified silica chromatographic microspheres according to claim 4, characterized in that, The mass ratio of the secondary mesoporous core-shell silica, γ-aminopropyltriethoxysilane, and anhydrous toluene in step (3) is 1:(3.5~4):(50~60). The reflux reaction is carried out at a temperature of 110~120℃ for a duration of 20~24h.

9. The method for preparing modified silica chromatographic microspheres according to claim 4, characterized in that, In step (4), the molar ratio of amino groups, dehydroabsic acid, ethyl isocyanate, and aldehyde functional monomers on the surface of the amino-modified silica is 1:(1~1.2):(1~1.1):(1~1.1), the mass ratio of amino-modified silica to solvent is 1:(50~60), and the stirring reaction time is 12~14h. The solvent is one of methanol, N,N-dimethylformamide, and tetrahydrofuran.