Amphiphilic covalent organic framework mixed mode chromatographic stationary phase as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of chromatographic separation, and particularly relates to an amphiphilic covalent organic framework mixed mode chromatographic stationary phase as well as a preparation method and application thereof. Silica gel is used as a carrier, and a covalent organic framework is immobilized on the surface of the silica gel in situ through chemical bonds; and polymerizing the ionic liquid with the hydrophilic group in the covalent organic framework by using an in-situ polymerization method to obtain the covalent organic framework. The stationary phase provided by the invention can generate multiple interactions such as hydrophobicity, pi-pi, hydrophilicity, hydrogen bonds and the like with an analyte, can provide high separation selectivity for components with similar structures, and is expected to be widely applied to the field of separation and analysis of complex systems.

Description

Technical Field

[0001] The invention belongs to the technical field of chromatographic separation, and in particular relates to an amphiphilic covalent organic skeleton mixed mode chromatographic stationary phase and a preparation method and application thereof. Background Art

[0002] The need for accurate determination of biomolecules, pesticides, drugs and other substances is crucial in the clinical, environmental and food safety fields. However, the variety and complex chemical composition of these complex samples seriously affect the accuracy and reliability of the measurement results, which poses a huge challenge to separation and analysis technology. In order to achieve high separation ability of complex samples using high-performance liquid chromatography (HPLC), the selectivity of the stationary phase used is crucial. However, conventional stationary phases have shortcomings such as single separation mode, low selectivity, long separation time and high consumption of organic reagents, which limit their further application in complex systems such as clinical, environmental and food. Therefore, the development of efficient new chromatographic stationary phases to meet the separation requirements of complex systems has become a research hotspot in the field of chromatography.

[0003] Covalent organic frameworks (COFs) are a new type of porous crystalline network polymers constructed from covalently bonded light elements through dynamic covalent chemistry. Thanks to their interconnected porosity, ultra-low density, large surface area, and high chemical stability, COFs have been very successful since their introduction, and have outstanding potential applications in adsorption and separation, heterogeneous catalysis, biochemical sensors, energy storage, and other fields. In the field of chromatographic separation, COFs have been widely used in the field of spherical SiO 2 Immobilizing different COFs on the surface is a common method to prepare COFs-based stationary phases. 2 The stationary phase relies on the hydrophobic properties of the COFs aromatic skeleton, showing good application potential for hydrophobic compounds such as alkylbenzenes, polycyclic aromatic hydrocarbons and organic halides, but the separation selectivity for polar compounds is limited. In addition, it is reported that COFs will experience a decrease in porosity and crystallinity after solvent exchange, which is contrary to the fact that HPLC needs to frequently change the mobile phase composition to improve the separation effect. After using different mobile phases, the structural defects of COFs will lead to low separation selectivity, low column efficiency and high column pressure, which will seriously limit their application potential in HPLC.

[0004] It can be seen that developing a simple and effective method to regulate SiO 2 @It is particularly urgent to identify the hydrophilic sites of the COFs stationary phase and maintain its structural stability. Summary of the invention

[0005] The present invention is to overcome the COFs modified silica gel (COFs@SiO2 ) The problem of limited separation selectivity and poor stability of polar compounds was solved by COFs@SiO 2 The in-situ polymerization of ionic liquids with hydrophilic groups on the stationary phase surface provides a highly stable amphiphilic covalent organic framework mixed mode chromatographic stationary phase. The chromatographic stationary phase has a stable structure and can achieve effective separation of polar compounds. When applied to high performance liquid chromatography columns, it has high column efficiency and low column pressure.

[0006] To achieve the above technical objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides an amphiphilic covalent organic skeleton mixed mode chromatographic stationary phase, wherein the chromatographic stationary phase uses silica gel as a carrier, and the covalent organic skeleton is in situ immobilized on the surface of the silica gel through chemical bonds; and then an ionic liquid with a hydrophilic group is polymerized in the covalent organic skeleton by an in situ polymerization method to obtain a covalent organic skeleton-based silica gel microsphere modified with a polymerized ionic liquid, which is an amphiphilic covalent organic skeleton mixed mode chromatographic stationary phase, which can be used as a high performance liquid chromatography stationary phase. Among them, the ionic liquid with a hydrophilic group can stabilize the covalent organic skeleton after polymerization, and the hydrophilic group of the ionic liquid can improve the strong hydrophobicity of the covalent organic skeleton, so that it has hydrophilic properties, so as to achieve separation of polar compounds.

[0008] As a specific implementation, the silica gel is amino silica gel; the covalent organic skeleton is obtained by reacting 1,4-dialdehyde-2,5-divinylbenzene (1,4-Benzenedicarboxaldehyd, DVA) and 1,3,5-tris(4-aminophenyl)benzene 1,3,5-tris(4-aminophenyl)benzene, TAPB) as raw materials; the 1,4-dialdehyde-2,5-divinylbenzene with aldehyde group will be connected to the amino group on the surface of amino silica gel through chemical bonds, so that the covalent organic skeleton is in situ immobilized on the silica gel surface.

[0009] As a specific implementation, the hydrophilic group in the ionic liquid is a sulfonic acid group. Specifically, the ionic liquid is a 1-sulfopropyl-3-vinylimidazoliumchloride-based ionic liquids (sIL).

[0010] The structure formed by the polymerization of the ionic liquid in the covalent organic framework is shown in formula (I):

[0011]

[0012] In addition, the present invention provides a method for preparing an amphiphilic covalent organic framework mixed mode chromatographic stationary phase, which specifically comprises the following steps:

[0013] Amino silica gel, 1,4-dialdehyde-2,5-divinylbenzene, 1,3,5-tri(4-aminophenyl)benzene and acetic acid were dispersed in acetonitrile, reacted at room temperature for 72 hours, washed and dried to obtain COFs modified silica gel, namely SiO 2 @COF DVA-TAPB The amino silica gel, 1,4-dialdehyde-2,5-divinylbenzene, 1,3,5-tris(4-aminophenyl)benzene and acetic acid are used in a ratio of 3.0 g: 0.3 g: 0.4 g: 15 mL.

[0014] The COFs modified silica gel obtained in the above step 1, 1-propylsulfonic acid-3-vinyl imidazolium chloride ionic liquid and azobisisobutyronitrile were added to dimethyl sulfoxide; the reaction was carried out at room temperature for 0.5 to 2 hours under a nitrogen atmosphere, and then the temperature was raised to 60 to 110°C for 18 to 36 hours, and then washed and dried to obtain SiO 2 @COF DVA-TAPB / PsIL microspheres. The COFs modified silica gel, 1-propylsulfonic acid-3-vinylimidazolium chloride ionic liquid, azobisisobutyronitrile and dimethyl sulfoxide are used in a ratio of 3.0 g: 0.1-3 g: 0.1-0.5 g: 50-200 mL, preferably, the COFs modified silica gel, 1-propylsulfonic acid-3-vinylimidazolium chloride ionic liquid, azobisisobutyronitrile and dimethyl sulfoxide are used in a ratio of 3.0 g: 2.0 g: 0.3 g: 100 mL.

[0015] Furthermore, the present invention also provides the use of an amphiphilic covalent organic framework mixed-mode chromatographic stationary phase in separating polar compounds, wherein the polar compounds are nucleoside / base compounds, sulfonamide antibiotics, alkylbenzenes, aniline compounds, phenol compounds, organophosphorus pesticides and / or benzoylurea insecticides.

[0016] Among them, the nucleoside / base compounds include 2-amino-4-chloro-6-methoxypyrimidine, 6-chloro-7-azapurine, thymine, β-thymidine, 2'-deoxyuridine, 5-methyluridine, adenosine, 2-aminoadenosine and cytosine;

[0017] Sulfonamide antibiotics include sulfonamide, sulfaguanidine, sulfapyridine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxazole;

[0018] Alkylbenzenes include toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-pentylbenzene;

[0019] Aniline compounds include aniline, o-toluidine, N-methylaniline, m-nitroaniline, o-nitroaniline, and 1-naphthylamine;

[0020] Phenol compounds include 2,6-dichlorophenol, hydroquinone, phenol, o-cresol, 2,5-xylenol, and 3-nitrophenol;

[0021] Organophosphorus pesticides include diazinon, chlorpyrifos, fenthion, and chlorpyrifos;

[0022] Benzoylurea insecticides include fluazifop, chlorpyrifos, fluazifop, and fluorobenzoate.

[0023] The chromatographic stationary phase is used in a high performance liquid chromatography column when used to separate polar compounds. The preparation method of the high performance liquid chromatography column comprises:

[0024] 1.7-3.4 g of the chromatographic stationary phase was taken, dispersed in methanol, loaded into the column at a pressure of 40 MPa, maintained for 30 min, and finally flushed the chromatographic column with pure methanol at 0.2 mL / min for 10 h to complete the filling of the chromatographic column.

[0025] Compared with the prior art, the beneficial effects of the present invention include:

[0026] (1) The polymerized ionic liquid formed by the polymerization of ionic liquid monomers has the excellent properties of both ionic liquids and polymers. The present invention introduces ionic liquids into the pores of COFs for in-situ polymerization, which can not only use the hydrophilic properties of ionic liquids to introduce multiple action sites to achieve efficient separation of multiple types of analytes; it can also cleverly use the mechanical strength of the polymerized ionic liquid to support the pores of COFs, thereby enhancing the applicability of the COFs-based stationary phase in different mobile phases.

[0027] (2) The stationary phase provided by the present invention can generate multiple interactions such as hydrophobic, π-π, hydrophilic, and hydrogen bonds with the analyte, and can provide high separation selectivity for components with similar structures, and is expected to be widely used in the field of separation and analysis of complex systems.

[0028] (3) The present invention found that in situ polymerized ionic liquids can support COF DVA-TAPB The pores promote mass transfer to improve column efficiency. When applied to high performance liquid chromatography columns, the column efficiency is as high as 21626 pieces / m. At the same time, its structural stability is improved. When applied to different organic solvent mobile phases, the stability and reproducibility are good. After 10 consecutive injections, the relative standard deviation of retention time and peak area is less than 1.47%.

[0029] (4) SiO provided by the present invention 2 @COF DVA-TAPB The / PsIL stationary phase has a high density of multiple interaction sites and exhibits excellent amphiphilicity. It can achieve complete separation of non-polar and weakly polar compounds in the reversed-phase chromatography separation mode, and can also achieve effective separation of polar compounds in the hydrophilic interaction mode, with a selectivity factor of up to 6.05.2 @COF DVA-TAPB Compared with the stationary phase, it exhibits ultra-high separation selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart for preparing the amphiphilic covalent organic framework mixed mode chromatographic stationary phase of the present invention.

[0031] Figure 2 Amino silica gel (a), SiO 2 @COF DVA-TAPB (b) and SiO 2 @COF DVA-TAPB SEM images of / PsIL(c) and SiO 2 @COF DVA-TAPB / PsIL X-ray energy spectrum (dh).

[0032] Figure 3 SiO 2 @COF DVA-TAPB (a) and SiO 2 @COF DVA-TAPB / PsIL(b) Water contact angle diagram.

[0033] Figure 4 It is amino silica gel, SiO 2 @COF DVA-TAPB and SiO 2 @COF DVA-TAPB Infrared spectrum of / PsIL.

[0034] Figure 5 It is amino silica gel, SiO 2 @COF DVA-TAPB and SiO 2 @COF DVA-TAPB Nitrogen adsorption-desorption isotherms (a) and pore size distribution diagram (b) of / PsIL.

[0035] Figure 6 It is a nucleoside / base substance in SiO 2 @COF DVA-TAPB Relationship between capacity factor k on / PsIL column and water content in mobile phase.

[0036] Figure 7 It is a nucleoside / base substance in SiO 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Figure 7Chromatographic peaks 1 to 9 in a and 7b are 2-amino-4-chloro-6-methoxypyrimidine, 6-chloro-7-azapurine, thymine, β-thymidine, 2'-deoxyuridine, 5-methyluridine, adenosine, 2-aminoadenosine and cytosine, respectively. Figure 8 Sulfonamide antibiotics in SiO 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Figure 8 Chromatographic peaks 1 to 6 in a and 8b are sulfonamide, sulfaguanidine, sulfapyridine, sulfadimethoxine, sulfamethoxypyridazine and sulfamethoxazole, respectively.

[0037] Fig. 9 Sulfonamide antibiotics in SiO 2 @COF DVA-TAPB Relationship between capacity factor k on / PsIL column and water content in mobile phase.

[0038] Fig.10 Alkylbenzenes in SiO 2 @COF DVA-TAPB Relationship between capacity factor k on / PsIL column and acetonitrile content in mobile phase.

[0039] Fig.11 Alkylbenzenes in SiO 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Fig.11 Chromatographic peaks 1 to 5 in a and 11b are toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-pentylbenzene, respectively.

[0040] Fig.12 Aniline in SiO 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Fig.12 The chromatographic peaks 1 to 6 in a and 12b are aniline, o-toluidine, N-methylaniline, m-nitroaniline, o-nitroaniline, and 1-naphthylamine, respectively.

[0041] Fig.13 Phenols in SiO 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Fig.13The chromatographic peaks 1 to 6 in a and 13b are 2,6-dichlorophenol, hydroquinone, phenol, o-cresol, 2,5-xylenol, and 3-nitrophenol, respectively.

[0042] Fig.14 Is organophosphorus pesticide in SiO 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Fig.14 The chromatographic peaks 1 to 4 in a and 14b are diazinon, chlorpyrifos, fenthion and chlorpyrifos, respectively.

[0043] Fig.15 Benzoyl urea insecticides are 2 @COF DVA-TAPB / PsIL chromatographic column (a) and SiO 2 @COF DVA-TAPB Chromatographic separation on the column (b). Fig.15 The chromatographic peaks 1 to 4 in a and 15b are fluazifop, thiocarbamide, fluazifop and flubendiamide, respectively.

[0044] Fig.16 SiO 2 @COF DVA-TAPB / PsIL chromatographic column stability test chart. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] A preparation process of an amphiphilic covalent organic framework mixed mode chromatography stationary phase, see Figure 1 , specifically including the following steps:

[0048] 1.SiO 2 @COF DVA-TAPB Preparation of microspheres

[0049] 3.0 g of amino silica gel (purchased from Suzhou Nano-Micro Technology Co., Ltd., 5 μm), 0.3 g of DVA, 0.4 g of TAPB and 15 mL of acetic acid (12 mol / L) were added to 150 mL of acetonitrile for ultrasonic dispersion for 15 min, and the reaction solution was placed at room temperature for reaction for 72 h. After the reaction, tetrahydrofuran and anhydrous ethanol were used for centrifugal washing three times, and the mixture was centrifuged and dried in a 60°С vacuum drying oven for 12 h to obtain SiO 2 @COF DVA-TAPB Microspheres.

[0050] 2.SiO 2 @COF DVA-TAPB Optimization of the preparation method of PsIL microspheres

[0051] The SiO obtained in step 1 above 2 @COF DVA-TAPB Microspheres, sIL and azobisisobutyronitrile were ultrasonically dispersed in dimethyl sulfoxide; stirred at room temperature for 1 hour under nitrogen atmosphere, then heated to 80°С and continued to react for 24 hours; after the reaction was completed, cooled to room temperature, centrifuged and washed with methanol and anhydrous ethanol three times in sequence; dried in a 60°С vacuum drying oven for 12 hours to obtain SiO 2 @COF DVA-TAPB / PsIL microspheres.

[0052] SiO 2 @COF DVA-TAPB The optimized dosage of microspheres, sIL, azobisisobutyronitrile, and dimethyl sulfoxide is shown in Table 1 below.

[0053] Table 1. SiO 2 @COF DVA-TAPB Optimization of raw material dosage for core-shell microspheres

[0054] <![CDATA[SiO 2 @COF DVA-TAPB (g)]]> sIL(g) Azobisisobutyronitrile (mg) Dimethyl sulfoxide (mL) 3.0 2.0 500 80 3.0 1.0 300 100

[0055] The experimental results show that SiO 2 @COF DVA-TAPB When the dosage ratio of sIL, azobisisobutyronitrile and dimethyl sulfoxide is 3.0g:2.0g:500mg:80mL, the elemental analysis results show that SiO 2 @COF DVA-TAPB The contents of C, H, N and S in / PsIL are 13.39%, 1.50%, 1.87% and 0.42% respectively; 2 @COF DVA-TAPB When the dosage ratio of sIL, azobisisobutyronitrile and dimethyl sulfoxide is 3.0g:1.0g:300mg:100mL, the elemental analysis results show that SiO 2 @COF DVA-TAPBThe contents of C, H, N and S in the SiO / PsIL are 22.84%, 2.57%, 2.94% and 1.43%, respectively. Therefore, the excessive amount of sIL will cause self-aggregation, which is not conducive to the formation of sIL on SiO 2 @COF DVA-TAPB Therefore, SiO 2 @COF DVA-TAPB The dosage ratio of sIL, azobisisobutyronitrile and dimethyl sulfoxide is 3.0 g:1.0 g:300 mg:100 mL. 2 @COF DVA-TAPB / PsIL is denoted as optimized SiO 2 @COF DVA-TAPB / PsIL.

[0056] SEM observation of SiO 2 @COF DVA-TAPB and optimized SiO 2 @COF DVA-TAPB / Microstructure of PsIL. Figure 2 a shows that the particle size of amino silica gel is about 5 μm; Figure 2 b shows SiO 2 @COF DVA-TAPB The particle size is about 5.4 μm, and a large number of protruding DVA-TAPB-COFs particles can be observed on its rough surface; SiO 2 @COF DVA-TAPB / PsIL presents a regular spherical morphology with a particle size of approximately 5.6 μm ( Figure 2 c) SiO 2 @COF DVA-TAPB / X-ray spectrum image of PsIL( Figure 2 dh) shows that in addition to Si and O elements, C, N and S elements are evenly distributed in SiO 2 @COF DVA-TAPB / PsIL surface. Among them, the presence of S element fully confirms that polymerized 1-propylsulfonic acid-3-vinylimidazolium chloride ionic liquid (polymerized sIL, PsIL) has been successfully modified in the DVA-TAPB-COFs framework.

[0057] Detection of SiO 2 @COF DVA-TAPB and optimized SiO 2 @COF DVA-TAPB The water contact angle of / PsIL is shown in Figure 3 As shown in a, SiO 2 @COF DVA-TAPB The water contact angle can reach 104.7°, showing strong hydrophobic characteristics. Figure 3b shows that after modification of PsIL, SiO 2 @COF DVA-TAPB The water contact angle of / PsIL is 69.2°, showing good hydrophilicity. This property is expected to promote the 2 @COF DVA-TAPB / PsIL stationary phase has good separation effect for polar analytes in hydrophilic chromatography mode.

[0058] Amino silica gel, SiO 2 @COF DVA-TAPB and optimized SiO 2 @COF DVA-TAPB The infrared spectrum of / PsIL is shown in Figure 4 As shown. SiO 2 @COF DVA-TAPB At 1620cm -1 The absorption peaks at 1519 and 1428 cm are attributed to the C=N stretching vibration in the DVA-TAPB-COFs skeleton. -1 The absorption peaks at 1046, 816, and 470 cm-1 are attributed to the aromatic skeleton vibration of DVA-TAPB-COFs. -1 The absorption peaks at are attributed to the Si-O-Si antisymmetric stretching vibration, SiO-H symmetric stretching vibration and Si-O bending vibration of amino silica gel. 2 @COF DVA-TAPB / PsIL at 1620cm -1 The absorption peak at 1190 cm-1 is significantly enhanced, which may be caused by the skeleton vibration of the imidazole ring. -1 With 1068cm -1 The characteristic peaks on the left and right are covered by stronger Si-O characteristic peaks.

[0059] SiO 2 @COF DVA-TAPB and optimized SiO 2 @COF DVA-TAPB / PsILN 2 Adsorption / desorption isotherms such as Figure 5 a. It is worth noting that in SiO 2 @COF DVA-TAPB and SiO 2 @COF DVA-TAPB A typical type IV isotherm with an H1 hysteresis loop was observed on the Mg / PsIL, indicating the presence of a mesoporous structure. Figure 5 As shown in b, relative to amino silica gel, SiO 2 @COF DVA-TAPBA new hole of 2.32 nm appeared, which originated from COFs, suggesting that COFs were successfully grown on the surface of amino silica gel. The molecular size of PsIL is It can enter the pores of 2.32nm to polymerize. 2 @COF DVA-TAPB No 2.28 nm pores were observed in PsIL, which suggests that PsIL is DVA-TAPB Successful polymerization in the pores.

[0060] 3. Take 2.5g of the optimized SiO prepared in step 2 above 2 @COF DVA-TAPB The microspheres were ultrasonically dispersed in 50 mL of methanol, loaded into the homogenate, and loaded into a column (4.6 mm × 150 mm id, Dalian Yilite Analytical Instrument Co., Ltd.) at a pressure of 40 MPa for 30 min. Finally, a liquid chromatography infusion pump was used to infuse the column at a rate of 0.2 mL min -1 The column was flushed with pure methanol for 10 h to complete the SiO 2 @COF DVA-TAPB / PsIL column filling. 2 @COF DVA-TAPB The chromatographic column filled with microspheres was used as a control. 2 @COF DVA-TAPB Steps for packing chromatographic columns with microspheres and optimized SiO 2 @COF DVA-TAPB The microspheres are packed in the same way as the chromatographic columns.

[0061] Example 2

[0062] The SiO prepared in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to test SiO 2 @COF DVA-TAPB / PsIL column hydrophilic selectivity and its separation ability for nucleoside / base substances. Chromatographic analysis conditions: mobile phase: acetonitrile / ammonium acetate solution (10mmol / L) = 95 / 5; column temperature: 40℃; flow rate: 1.0mL / min; injection volume: 5μL; detection wavelength: 260nm.

[0063] like Figure 6 As shown in Figure 2, when the volume fraction of water in the mobile phase changes from 5% to 40%, the seven nucleosides / bases react with SiO 2 @COF DVA-TAPBThe retention value on the / PsIL column decreases accordingly, which is consistent with the hydrophilic retention characteristics. It is worth noting that the retention factors of the two analytes, 2-amino-4-chloro-6-methoxypyrimidine and 6-chloro-7-azapurine, show a "U"-shaped curve with the volume fraction of water in the mobile phase, indicating that the column also has mixed-mode retention characteristics. Figure 7 As shown in a, chromatographic peaks 1 to 9 are 2-amino-4-chloro-6-methoxypyrimidine, 6-chloro-7-azapurine, thymine, β-thymidine, 2'-deoxyuridine, 5-methyluridine, adenosine, 2-aminoadenosine and cytosine, respectively. 2 @COF DVA-TAPB / PsIL column achieved good separation; however, under the same chromatographic conditions, the 9 nucleosides / bases were 2 @COF DVA-TAPB The chromatographic column cannot be used to separate Figure 7 b), and its retention order is the same as SiO 2 @COF DVA-TAPB These results show that PsIL enhances the SiO 2 @COF DVA-TAPB The hydrophilic selectivity of PsIL for nucleosides / bases further confirms the important role of PsIL in hydrophilic separation.

[0064] Example 3

[0065] The SiO prepared in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to detect SiO 2 @COF DVA-TAPB / PsIL column separation ability for sulfonamide antibiotics. Chromatographic analysis conditions: mobile phase: acetonitrile / water = 82.5 / 17.5; column temperature: 40°C; flow rate: 1.0mL / min; injection volume: 5μL; detection wavelength: 270nm.

[0066] like Figure 8 As shown in a, chromatographic peaks 1 to 6 are sulfonamide, sulfaguanidine, sulfapyridine, sulfadimethoxine, sulfamethoxypyridazine, and sulfamethoxazole, respectively. The six sulfonamide antibiotics are 2 @COF DVA-TAPB / PsIL column achieved rapid and efficient separation within 8 min; however, due to the SiO 2 @COF DVA-TAPB Weak hydrophilicity, which is in SiO 2 @COF DVA-TAPB The chromatographic peaks on the column overlap severely ( Figure 8 b) If Fig. 9 As shown, sulfonamide antibiotics are 2 @COF DVA-TAPB The retention on the / PsIL column showed a U-shaped trend with the water content in the mobile phase, that is, the separation of sulfonamide antibiotics changed from a hydrophilic-dominated mechanism to a reversed-phase-dominated mechanism with increasing water content, indicating that multiple effects were involved in the SiO 2 @COF DVA-TAPB / PsIL stationary phase separation process.

[0067] Example 4

[0068] The SiO prepared in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to test SiO 2 @COF DVA-TAPB / PsIL column hydrophobic selectivity and its separation ability for alkylbenzenes. Chromatographic analysis conditions: mobile phase: acetonitrile / water = 50 / 50; column temperature: 40℃; flow rate: 1.0mL / min; injection volume: 5μL; detection wavelength: 254nm.

[0069] like Fig.10 As shown in the figure, with the increase of acetonitrile content in the mobile phase, the capacity factor k of alkylbenzene gradually decreases, indicating that SiO 2 @COF DVA-TAPB / PsIL chromatographic column has typical reverse phase characteristics. Fig.11 As shown in a, chromatographic peaks 1 to 5 are toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-pentylbenzene, respectively. 2 @COF DVA-TAPB / PsIL columns achieved good separation with good peak shapes, but they 2 @COF DVA-TAPB Cannot be completely separated on the chromatographic column ( Fig.11 b) Under the same chromatographic conditions, alkylbenzene 2 @COF DVA-TAPB The separation time on the PsIL column is shorter than that on the SiO 2 @COF DVA-TAPB chromatographic column, which indicates that although PsIL reduces the hydrophobicity of DVA-TAPB-COFs, it improves the hydrophobic selectivity towards alkylbenzenes.

[0070] Example 5

[0071] Using SiO in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to detect SiO 2 @COF DVA-TAPB / PsIL column separation ability for aniline substances. Chromatographic analysis conditions: mobile phase: acetonitrile / water = 35 / 65; column temperature: 40°C; flow rate: 1.0mL / min; injection volume: 5μL; detection wavelength: 254nm.

[0072] like Fig.12 As shown in a, chromatographic peaks 1 to 6 are aniline, o-toluidine, N-methylaniline, m-nitroaniline, o-nitroaniline, and 1-naphthylamine, respectively; 2 @COF DVA-TAPB Compared with the chromatographic column ( Fig.12 b), SiO 2 @COF DVA-TAPB The / PsIL column showed higher selectivity for the six anilines under high water content mobile phase conditions, with a column efficiency of up to 21626 blocks / m. Except for m-nitroaniline, the other anilines were 2 @COF DVA-TAPB The peak order of the / PsIL column is consistent with its hydrophobicity, indicating that the separation process is driven by hydrophobic interaction. Due to the electron-withdrawing inductive effect of the nitro group, the acidity of m-nitroaniline is relatively large, and its reaction with SiO 2 @COF DVA-TAPB / PsIL has a stronger hydrogen bonding effect, resulting in its retention being greater than that of o-methylaniline and N-methylaniline.

[0073] Example 6

[0074] Using SiO in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to detect SiO 2 @COF DVA-TAPB / PsIL column separation ability for phenols. Chromatographic analysis conditions: mobile phase: acetonitrile / water = 30 / 70; column temperature: 40°C; flow rate: 1.0 mL / min; injection volume: 5 μL; detection wavelength: 260 nm.

[0075] like Fig.13 As shown in a, chromatographic peaks 1 to 6 are 2,6-dichlorophenol, hydroquinone, phenol, o-cresol, 2,5-xylenol, and 3-nitrophenol, respectively. 2 @COF DVA-TAPBThe HPLC-MS / MS / MS columns achieved good separation on the SiO / PsIL column, and the selectivity factor between hydroquinone and phenol was as high as 6.05. However, the same high water content mobile phase failed to remove the highly hydrophobic 2,6-dichlorophenol from the SiO / PsIL column within 35 min. 2 @COF DVA-TAPB Eluted from the column ( Fig.13 b), which may be due to the reaction of 2,6-dichlorophenol with SiO 2 @COF DVA-TAPB This result further confirms that PsIL improves the hydrophobicity of SiO by reducing the hydrophobicity of DVA-TAPB-COFs. 2 @COF DVA-TAPB / PsIL separation selectivity.

[0076] Example 7

[0077] Using SiO in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to detect SiO 2 @COF DVA-TAPB / PsIL column separation ability for organophosphorus pesticides. Chromatographic analysis conditions: mobile phase: acetonitrile / water = 60 / 40; column temperature: 40°C; flow rate: 1.0mL / min; injection volume: 5μL; detection wavelength: 225nm.

[0078] like Fig.14 As shown in a, chromatographic peaks 1 to 4 are diazinon, chlorpyrifos, fenthion, and chlorpyrifos, respectively. 2 @COF DVA-TAPB / PsIL column achieved rapid and efficient separation within 8 min with symmetrical peak shape; however, under the same chromatographic conditions, 2 @COF DVA-TAPB The peaks of the chromatographic column are severely broadened ( Fig.14 b), poor column efficiency.

[0079] Example 8

[0080] Using SiO in Example 1 2 @COF DVA-TAPB / PsIL Column and SiO 2 @COF DVA-TAPB The chromatographic column is used as a high performance liquid chromatography column to detect SiO 2 @COF DVA-TAPB / PsIL column separation ability for benzoylurea insecticides. Chromatographic analysis conditions: mobile phase: (methanol / acetonitrile = 90 / 10) / water = 95 / 5; column temperature: 40°C; flow rate: 1.0 mL / min; injection volume: 5 μL; detection wavelength: 254 nm.

[0081] like Fig.15 As shown in a, the chromatographic peaks 1 to 4 are fluazifop, chloranil, fluazifop, and flubenzuron, respectively. SiO 2 @COF DVA-TAPB / PsIL column quickly separated four benzoylurea pesticides within 5 min; however, SiO 2 @COF DVA-TAPB The chromatographic column was unable to effectively separate chlorfenapyr and flubendiamide ( Fig.15 b) Four benzoylurea insecticides on SiO 2 @COF DVA-TAPB The peak order on the / PsIL column was fluazifop (logP = 6.78) < thiocarbamide (logP = 4.55) < fluazifop (logP = 3.68) < fluorobenzene (logP = 5.49), which was inconsistent with the reversed-phase separation mechanism. The weak retention of fluazifop and thiocarbamide may be due to the large number of strongly electronegative fluorine atoms in their structures that bind to SiO 2 @COF DVA-TAPB / PsIL SO 3 - An electrostatic repulsion effect is generated.

[0082] Example 9

[0083] Benzoylurea insecticides were used to evaluate the SiO 2 @COF DVA-TAPB / Stability of PsIL chromatographic column. Chromatographic analysis conditions: mobile phase: (methanol / acetonitrile = 90 / 10) / water = 95 / 5; column temperature: 40°C; flow rate: 1.0 mL / min; injection volume: 5 μL; detection wavelength: 254 nm.

[0084] like Fig.16 As shown in the figure, the chromatograms of ten consecutive injections in one day showed no obvious changes in chromatographic peak shape, retention time and peak area. The relative standard deviation of retention time was between 0.04% and 0.14%, and the relative standard deviation of peak area was between 1.36% and 1.47%. The relative standard deviations of retention time and peak area were both small, indicating that SiO 2 @COF DVA-TAPB The / PsIL chromatographic column has good reproducibility and stability, which further confirms that PsIL plays a supporting role inside the pores of COFs.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An amphiphilic covalent organic framework mixed mode chromatographic stationary phase, characterized in that: The chromatographic stationary phase uses silica gel as a carrier, and the covalent organic skeleton is in situ fixed on the surface of the silica gel through chemical bonds; then the ionic liquid with hydrophilic groups is polymerized in the covalent organic skeleton by in situ polymerization to obtain the chromatographic stationary phase.

2. The amphiphilic covalent organic framework mixed mode chromatography stationary phase according to claim 1, characterized in that: The silica gel is amino silica gel; the covalent organic skeleton is obtained by reacting 1,4-dialdehyde-2,5-divinylbenzene and 1,3,5-tris(4-aminophenyl)benzene.

3. The amphiphilic covalent organic framework mixed mode chromatography stationary phase according to claim 2, characterized in that: The hydrophilic group in the ionic liquid is a sulfonic acid group.

4. The amphiphilic covalent organic framework mixed mode chromatography stationary phase according to claim 3, characterized in that: The ionic liquid is 1-propylsulfonic acid-3-vinylimidazolium chloride ionic liquid.

5. The amphiphilic covalent organic framework mixed mode chromatography stationary phase according to claim 4, characterized in that: The structure formed by the polymerization of the ionic liquid in the covalent organic framework is shown in formula (I):

6. The method for preparing the amphiphilic covalent organic framework mixed mode chromatography stationary phase according to claim 4, characterized in that: include: Step 1: Disperse amino silica gel, 1,4-dialdehyde-2,5-divinylbenzene, 1,3,5-tri(4-aminophenyl)benzene and acetic acid in acetonitrile, react at room temperature for 72 hours, wash and dry to obtain COFs modified silica gel; Step 2: Add the COFs modified silica gel, 1-propylsulfonic acid-3-vinylimidazolium chloride ionic liquid and azobisisobutyronitrile obtained in the above step 1 to dimethyl sulfoxide; react at room temperature for 0.5 to 2 hours under a nitrogen atmosphere, then heat to 60 to 110° C. to react for 18 to 36 hours, wash and dry to obtain.

7. The preparation method according to claim 6, characterized in that: In step 1, the amount ratio of the amino silica gel, 1,4-dialdehyde-2,5-divinylbenzene, 1,3,5-tri(4-aminophenyl)benzene and acetic acid is 3.0 g:0.3 g:0.4 g:15 mL.

8. The preparation method according to claim 6, characterized in that: In step 2, the amount ratio of the COFs modified silica gel, 1-propylsulfonic acid-3-vinylimidazolium chloride ionic liquid, azobisisobutyronitrile and dimethyl sulfoxide is 3.0 g: 0.1-3 g: 0.1-0.5 g: 50-200 mL.

9. Use of the amphiphilic covalent organic framework mixed mode chromatography stationary phase according to any one of claims 1 to 5 in separating polar compounds, characterized in that: The polar compounds are nucleoside / base compounds, sulfonamide antibiotics, alkylbenzenes, aniline compounds, phenol compounds, organophosphorus pesticides and / or benzoylurea insecticides.

10. The use according to claim 9, characterized in that: Nucleoside / base compounds include 2-amino-4-chloro-6-methoxypyrimidine, 6-chloro-7-azapurine, thymine, β-thymidine, 2'-deoxyuridine, 5-methyluridine, adenosine, 2-aminoadenosine and cytosine; Sulfonamide antibiotics include sulfonamide, sulfaguanidine, sulfapyridine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxazole; Alkylbenzenes include toluene, ethylbenzene, n-propylbenzene, n-butylbenzene, and n-pentylbenzene; Aniline compounds include aniline, o-toluidine, N-methylaniline, m-nitroaniline, o-nitroaniline, and 1-naphthylamine; Phenol compounds include 2,6-dichlorophenol, hydroquinone, phenol, o-cresol, 2,5-xylenol, and 3-nitrophenol; Organophosphorus pesticides include diazinon, chlorpyrifos, fenthion, and chlorpyrifos; Benzoylurea insecticides include fluazifop, chlorpyrifos, fluazifop, and fluorobenzoate.

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