CN107297201B - 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column and application - Google Patents
4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column and application Download PDFInfo
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Abstract
The invention discloses a 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column, which can be used for separation and analysis of polar compounds, and the preparation method comprises the following steps: introducing a mixed solution of tetramethoxysilane and chloropropyltrimethoxysilane in a proper proportion into a pretreated capillary, heating for reaction to prepare a chloropropyl-silica gel hybrid monolithic column bed, then flushing excessive ammonia water solution of 4, 5-imidazole dicarboxylic acid into the chloropropyl-silica gel hybrid monolithic column bed, and heating to obtain the catalyst. The invention develops a novel functionalized organic-silica gel hybrid monolithic column by bonding water-soluble organic functional monomers, and the hybrid monolithic column can be applied to separation and analysis of different types of polar compounds in a water-rich or reversed-phase chromatographic mode.
Description
Technical Field
The invention relates to a 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column and a preparation method and application thereof, belonging to the technical field of chromatographic packing.
Background
At present, most of the applications of monolithic column materials mainly focus on reverse phase chromatographic separation, represented by C18 columns, which have good separation effect on nonpolar compounds, and some relevant types of monolithic columns have been commercialized, but the monolithic column materials have the following problems: it is difficult to achieve efficient separation of polar compounds. In addition, during preparation, the existing preparation method generally adopts water-insoluble organic functional monomers as a modifier, so that a large amount of organic solvent is required to be used in the preparation process, and the preparation method is relatively complex, uneconomical and environmentally-friendly.
Disclosure of Invention
Aiming at the prior art, the invention provides a 4, 5-imidazole dicarboxylic acid modified organic silica gel-hybrid monolithic column, a preparation method thereof and application thereof in separation and analysis of some common polar compounds, aiming at solving the problems of complexity, uneconomic performance, environmental pollution and the like of the preparation method of the prior art and simultaneously solving the problem that the existing monolithic column material cannot realize good separation of polar compounds.
The invention is realized by the following technical scheme:
a preparation method of a 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column comprises the following steps:
(a) selecting tetramethoxysilane and chloropropyltrimethoxysilane as precursors, and preparing a chloropropyl-silica hybrid silica monolithic column bed by a sol-gel method;
(b) and (2) washing the chloropropyl-silica gel hybrid silica gel monolithic column bed by using an excessive ammonia solution of 4, 5-imidazole dicarboxylic acid, and then placing the chloropropyl-silica gel hybrid silica gel monolithic column bed in a thermostat for reaction to obtain the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
In the step (a), the preparation method of the chloropropyl-silica gel hybrid silica gel monolithic column bed comprises the following steps: dissolving polyethylene glycol (PEG, M = 10000) in an acetic acid aqueous solution, and then slowly adding Tetramethoxysilane (TMOS) and Chloropropyltrimethoxysilane (CPTMS) into the acetic acid aqueous solution to obtain a mixed solution; placing the mixed solution in an ice-water bath condition for reaction until uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol in the ice-water bath condition, and introducing the sol into a treated capillary tube until the length of the sol is 30-35 cm; sealing two ends of the capillary tube with silicone grease, and then putting the capillary tube into a thermostat for reaction to complete a gelling process to obtain the chloropropyl-silicone hybrid monolithic column bed.
Furthermore, the dosage proportion relationship of the polyethylene glycol, the tetramethoxysilane and the chloropropyltrimethoxysilane is 240mg, 0.9m L and 0.3m L.
Preferably, the concentration of the acetic acid aqueous solution is 0.01 mol/L, and the dosage of the acetic acid aqueous solution used per 240mg of polyethylene glycol is 2.5 m L.
Preferably, the reaction time of the mixed solution under the ice-water bath condition is 3-5 h.
Preferably, the ultrasonic time is 3-5 min under the ice-water bath condition.
The processed capillary tube is obtained by sequentially washing a fused quartz capillary tube with the length of 40-50 cm with methanol and distilled water for 20min, sequentially washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water until the pH of the washed liquid is neutral (pH 7.0) (about 20 min), washing with methanol for 20min, and blowing with nitrogen at 120 ℃ for later use.
Preferably, the conditions for placing into the incubator for reaction are as follows: the reaction temperature is 50-70 ℃, and the reaction time is 12-14 h.
In the step (b), the concentration of the ammonia water solution of the 4, 5-imidazole dicarboxylic acid is more than or equal to 30mg/m L.
The excess means more than 2 times the volume of the capillary.
The reaction conditions of placing the chloropropyl-silica gel hybrid silica gel monolithic column bed in a thermostat for reaction are as follows: the reaction temperature is 60-80 ℃, and the reaction time is 23-25 hours.
The 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared by the method is used.
The 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column is applied to separation and analysis of polar compounds, and particularly can realize separation and analysis of some common polar compounds under the conditions of rich water or reversed phase chromatography.
Further, the water-rich chromatographic condition is H in a mobile phase2The O content (volume percent) is more than or equal to 90 percent, and the reverse phase chromatographic condition is that the acetonitrile content (volume percent) in the mobile phase is more than or equal to 15 percent.
Further, the polar compound is selected from amide compounds, nucleoside and nucleoside bases, amino acids, benzoic acid derivatives, phenolic compounds, and the like.
The 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column provided by the invention has the advantages that the monolithic column bed is modified by the water-soluble organic functional monomer, so that the preparation method is relatively simple, the step of washing the column by using an organic solvent (the organic solvent is not used in the whole modification process) is reduced, and the preparation method is green, economic and environment-friendly. The 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column can realize separation and analysis of some common polar compounds under the conditions of rich water or reversed phase chromatography, and can well overcome the inherent defects of the common monolithic column in the aspect of separation and analysis of the polar compounds. The use of few organic solvents in the water-rich chromatography mode also enables the monolithic column material of the present invention to perform separation and analysis of polar compounds under relatively green, economical and environmentally friendly conditions.
Drawings
FIG. 1 is a scanning electron micrograph of a 4, 5-imidazoledicarboxylic acid-modified organo-silica gel hybrid monolithic column of example 1, in which A is 1000 × at magnification, B is 3000 × at magnification, C is 5000 × at magnification, and D is 15000 × at magnification.
FIG. 2: the electroosmotic flow investigation result of the whole column is shown in a schematic diagram; when the pH is between 3.0 and 5.0, an anodic EOF is generated, and the size of the EOF is gradually reduced along with the increase of the pH; when the pH increases to around 5.6, the size of the EOF approaches zero; the EOF is reversed with further increase in pH to produce a cathodic EOF, in which the EOF gradually increases in size with increasing pH.
FIG. 3: chromatography of polar compounds on organo-silica hybrid monolithic columns (under water-rich chromatographic conditions), wherein a: chromatographic separation of 4 amides, 1. formamide; 2. n, N-dimethylformamide; 3. n, N-dimethylacetamide; 4. caprolactam is provided. B: chromatogram for 4 nucleoside and nucleobase, 1. uridine; 2. inosine; 3. thymidine; 4. hypoxanthine. C: chromatogram for 3 amino acids, 1. tyrosine; 2. phenylalanine; 3. tryptophan, a: chromatography on imidazole-1-acetic acid modified organo-silica gel hybrid monolith; b: chromatography on 4, 5-imidazole dicarboxylic acid modified organo-silica gel hybrid monolith column of example 1.
Separation conditions are as follows: a: 10mM NaH2PO4The buffer solution contains 4 percent of ACN, has pH of 3.0 and has voltage of-15 kV. B: 10mM NaH2PO4Buffer solution, pH 2.0, voltage: -8 kV. Ca: 10mM NaH2PO4Buffer solution containing 4% ACN, pH3.0, voltage: -20 kV. Cb: 10mM NaH2PO4buffer, pH3.0, voltage: -20 kV.
FIG. 4: chromatography profile of organo-silica hybrid monolith against polar compounds (under reverse phase chromatography conditions), wherein a: chromatographic fractionation of 3 benzoic acid derivatives, 1. thiourea; 2. p-hydroxybenzoic acid; 3. p-aminobenzoic acid; benzoic acid. B: chromatographic separation of 3 phenolic compounds, 1. hydroquinone; 2. phenol; 3. p-cresol.
Separation Conditions, Conditions: A: 20 mM NaH2PO4Buffer solution with different ACN contents, pH3.0, voltage of-20 kV. B: 10mM NaH2PO4The buffer solution contains 20 percent of ACN, has pH of 3.0 and has voltage of-20 kV.
Detailed Description
The present invention will be further described with reference to the following examples.
The instruments, reagents, materials and the like used in the following examples are conventional instruments, reagents, materials and the like in the prior art and are commercially available in a normal manner unless otherwise specified. Unless otherwise specified, the experimental methods, detection methods, and the like described in the following examples are conventional experimental methods, detection methods, and the like in the prior art.
Example 14 preparation and use of 5, 5-Imidazodicarboxylic acid modified organosilica-hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing 40 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 30cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 12 h under the condition of 55 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid monolithic column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (2 times of the capillary volume) ammonia solution (with the concentration of 60 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in a 75 ℃ oven for reaction for 24 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 90%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
EXAMPLE 24 preparation and application of 5, 5-Imidazoledicarboxylic acid modified organo-silica gel hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing 45 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle filled with 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the ice-water bath condition until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the ice-water bath condition, then introducing the sol into the treated capillary tube until the length is 35 cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat, reacting for 12 h under the condition of 60 ℃, completing the gelling process, and preparing a chloropropyl-silica gel hybrid monolithic column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (3 times of the capillary volume) ammonia solution (concentration is 50 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in a 70 ℃ oven for reaction for 24 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 92%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
Example 34 preparation and use of 5-Imidazoledicarboxylic acid modified organo-silica gel hybrid monolithic columns
The method comprises the following steps:
① preprocessing capillary tube, washing 50 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 35 cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 14 h under the condition of 55 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid integral column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (4 times of the capillary volume) ammonia solution (with the concentration of 55 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in an oven at 70 ℃ for reaction for 24 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 94%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
Example 44 preparation and use of 5-Imidazoledicarboxylic acid modified organo-silica gel hybrid monolithic columns
The method comprises the following steps:
① preprocessing capillary tube, washing 46 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 33 cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 12 h under the condition of 60 ℃, completing the gelling process, and preparing a chloropropyl-silica gel hybrid monolithic column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (2 times of the capillary volume) ammonia solution (concentration is 45 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, placing the monolithic column bed in a 75 ℃ oven for reaction for 24 hours, and finally preparing the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 94%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
EXAMPLE 54 preparation and use of 5-Imidazoledicarboxylic acid modified organo-silica gel hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing fused quartz capillary tube with length of 42 cm with methanol and water for 20min, washing with NaOH solution of 1 mol/L, water and hydrochloric acid of 1 mol/L for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and drying with nitrogen gas at 120 deg.C;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 5h under the ice-water bath condition until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 5min under the ice-water bath condition, then introducing the sol into the treated capillary tube until the length is 32 cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 12 h under the condition of 50 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid integral column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (3 times of the capillary volume) ammonia solution (with the concentration of 30mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in an oven at 80 ℃ for reaction for 24 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 90%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 20%).
EXAMPLE 64 preparation and application of 5-Imidazodicarboxylic acid modified organo-silica gel hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing fused quartz capillary tube with length of 41 cm with methanol and water for 20min, washing with NaOH solution of 1 mol/L, water and hydrochloric acid of 1 mol/L for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and drying with nitrogen gas at 120 deg.C;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 31 cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 12 h under the condition of 55 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid monolithic column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (2 times of the capillary volume) ammonia solution (concentration is 40 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, placing the monolithic column bed in a 75 ℃ oven for reaction for 24 hours, and finally preparing the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 92%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
Example preparation and use of 74, 5-Imidazoledicarboxylic acid-modified organo-silica gel hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing 48 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 34cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 12 h under the condition of 70 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid monolithic column;
③, washing the chloropropyl-silica gel hybrid monolithic column prepared in the step ② with water, then washing an excessive (3 times of the volume of the capillary tube) ammonia solution (the concentration is 35 mg/m L) of 4, 5-imidazole dicarboxylic acid into the monolithic column bed, and placing the monolithic column bed in a 65 ℃ oven for reaction for 24 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 94%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
Example 84 preparation and use of 5, 5-Imidazoledicarboxylic acid modified organo-silica gel hybrid monolithic columns
The method comprises the following steps:
① preprocessing capillary tube, washing 45 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 5h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 34cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 14 h under the condition of 50 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid integral column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (4 times of the capillary volume) ammonia solution (the concentration is 35 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in an oven at 80 ℃ for reaction for 24 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 94%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 25%).
EXAMPLE 94 preparation and use of 5-Imidazoledicarboxylic acid modified organo-silica gel hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing the capillary tube with 43 cm length with methanol and water for 20min, washing with NaOH solution 1 mol/L, water and hydrochloric acid 1 mol/L for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 3 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 3 min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 30cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 14 h under the condition of 55 ℃, completing the gelling process, and preparing a chloropropyl-silicone hybrid integral column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (2 times of the capillary volume) ammonia solution (with the concentration of 60 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in an oven at 80 ℃ for reaction for 22 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 92%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
Example 104 preparation and use of 5-Imidazodicarboxylic acid modified organo-silica gel hybrid monolithic column
The method comprises the following steps:
① preprocessing capillary tube, washing 49 cm long fused quartz capillary tube with methanol and water for 20min, washing with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing with water for 20min until pH of the washed liquid is neutral, washing with methanol for 20min, and blowing with nitrogen gas at 120 deg.C for use;
② dissolving 240mg polyethylene glycol (PEG, M = 10000) in a glass bottle containing 2.5M L0.01.01M acetic acid water solution, then slowly adding 0.9M L Tetramethoxysilane (TMOS) and 0.3M L M Chloropropyltrimethoxysilane (CPTMS) into the glass bottle, respectively, reacting the mixed solution for 4 h under the condition of ice-water bath until a uniform and transparent sol is formed, then carrying out ultrasonic treatment on the sol for 5min under the condition of ice-water bath, then introducing the sol into the treated capillary tube until the length is 33 cm, sealing two ends of the capillary tube with silicone grease, then placing the capillary tube into a thermostat and reacting for 14 h under the condition of 60 ℃, completing the gelling process, and preparing a chloropropyl-silica gel hybrid monolithic column;
③ washing the chloropropyl-silica gel hybrid monolithic column prepared in step ② with water, then washing an excessive (3 times of the capillary volume) ammonia solution (with the concentration of 55 mg/m L) of 4, 5-imidazole dicarboxylic acid into a monolithic column bed, and placing the monolithic column bed in a 75 ℃ oven for reaction for 26 hours to finally prepare the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column.
④ the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column prepared in step ③ is applied to a water-rich chromatographic condition (water content is more than 92%), so that the separation and analysis of polar and hydrophilic compounds such as amide, nucleoside base, amino acid and the like are realized, and the benzoic acid derivative and the phenolic compound can also obtain better separation effect under a reversed phase chromatographic condition (acetonitrile content is more than or equal to 15%).
The prepared 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column was characterized by the following parameters in example 1, and the characterization methods and results were as follows:
characterization by a scanning electron microscope: the monolithic column material was characterized by scanning electron microscopy using a field emission scanning electron microscopy (model S-4800, available from electronics of Japan). The results obtained are shown in FIG. 1. As can be seen from fig. 1, the monolithic column bed has a relatively uniform porous structure, and the monolithic column matrix is also well connected to the inner walls of the capillary tubes. In addition, we also found that the morphology of the monolithic column matrix did not change significantly before and after the modification of the chloropropyl-silica gel hybrid monolithic column with 4, 5-imidazoledicarboxylic acid.
Electroosmotic flow characterization (chemical characterization): in CEC separations, electroosmotic flow is a fundamental driving force, which is generated by charged groups on the surface of the stationary phase. For a silica monolithic column, electroosmotic flow is primarily caused by residual silicon hydroxyl groups on its surface. Due to the weak dissociation capability of the silicon hydroxyl groups, such monolithic columns tend to produce sufficiently large electroosmotic flows only in mobile phases with pH > 5.0. The method for solving the problem is to bond more charged functional groups on the surface of the silica gel monolithic column. The magnitude of the electroosmotic flow depends on the magnitude of the net charge density of all the charged groups, and correspondingly, the direction of the electroosmotic flow depends on the positive and negative of the net charge of all the charged groups, so that the regulation of the magnitude and the direction of the electroosmotic flow can be realized by changing the pH of the mobile phase. For the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column, when the pH is between 3.0 and 5.0, an anodic electroosmotic flow is generated, which indicates that the 4, 5-imidazole dicarboxylic acid is successfully bonded to the chloropropyl-silica gel hybrid monolithic column. Under the condition of lower pH, the dissociation of carboxyl and residual silicon hydroxyl on the surface of the stationary phase of the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column is inhibited, so that the positive and negative of the net charge are determined by the positively charged imidazole salt, and the electroosmotic flow of an anode is generated under the acidic condition. At the same time, we can observe that the magnitude of the electroosmotic flow is gradually reduced with the increase of the pH, which is mainly due to the fact that the dissociation of the carboxyl group and the residual silicon hydroxyl group is enhanced with the increase of the pH, thereby offsetting partial positive charges. When the pH increases by around 5.5, the magnitude of the electroosmotic flow approaches zero. As the pH is further increased, the dissociation of carboxyl and residual silicon hydroxyl is continuously enhanced, and the net charge of the column surface of the 4, 5-imidazole dicarboxylic acid modified organic-silica gel monolithic column is changed from positive to negative, so that a cathode electroosmotic flow is generated, and the magnitude of the electroosmotic flow is gradually increased along with the increase of the pH (as shown in figure 2).
Investigation of mechanical Properties and Permeability A4, 5-Imidazodicarboxylic acid-modified organo-silica gel hybrid monolith was connected to an HP L C liquid phase pump to generate (ACN/H)2O = 50/50, v/v) as the mobile phase, and the mechanical stability of the monolithic column was examined by testing the back pressure from the experimental results obtained, it was found that there is a good linear relationship between the back pressure and the flow rate (when the flow rate is increased from 0.001 m L/min to 0.011 m L/min, the back pressure is linearly increased from 0.5 MPa to 1.5 MPa), which indicates that the 4, 5-imidazoledicarboxylic acid-modified organo-silica gel hybrid monolithic column has good mechanical stability−12m2This indicates that the 4, 5-imidazole dicarboxylic acid modified organo-silica gel hybrid monolithic column has more satisfactory permeability.
Examination of reproducibility: reproducibility of IDS hybridized monolith columns was evaluated by measuring the relative standard deviation of retention times (RSDs) of thiourea. The results obtained when the in-day (n = 5) and in-day (n = 3) reproductions were examined on the same chromatographic column (in-day (n = 5): 2.504, 2.49, 2.475, 2.449, 2.427; in-day (n = 3): 2.699, 2.737, 2.785; column and column (n = 3): 2.743, 2.7, 2.89) were satisfactory with RSDs of 1.3% and 1.6%, respectively. The reproducibility from column to column (n = 3) was also within the acceptable range, with RSDs of 3.6%.
And (3) stability investigation: the retained performance and column efficiency of the monolithic column are not significantly reduced after continuous use for more than three weeks.
Next, using example 1 as an example, the chromatographic performance of the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column was examined, and the examined methods and results were as follows:
the monolithic column is connected into an Agilent G1600 series capillary electrophoresis apparatus, the temperature of the column is set to be 25 ℃, the wavelength of an ultraviolet detector is set to be 214 nm, and the separation performance of the monolithic column is examined by selecting proper mobile phase and voltage.
The monolithic column was examined for its separation performance under water-rich chromatographic conditions for different types of polar and hydrophilic compounds.
FIG. 3A shows the chromatographic separation of 4 amides (formamide, N, N-dimethylformamide, N, N-dimethylacetamide, caprolactam) on 4, 5-imidazole dicarboxylic acid modified organo-silica gel hybrid monolithic columns. As can be seen from the figure, the 4 amide compounds obtain better separation effect on the hybrid monolithic column. On the other hand, the amide compounds are difficult to realize effective separation on a conventional reversed-phase monolithic column due to the fact that irreversible adsorption exists, so that peak broadening and tailing are serious.
FIG. 3B shows the chromatographic separation of 4 nucleoside and nucleoside bases (uridine, inosine, thymidine, hypoxanthine) on a 4, 5-imidazole dicarboxylic acid modified organo-silica gel hybrid monolithic column. As can be seen, the baseline separation was obtained for the 4 nucleoside and nucleobase species under water-rich chromatographic conditions. For the separation of nucleosides and nucleobases, the highest column efficiency obtained was 129000N/m.
FIG. 3C, b, shows the chromatographic separation of 3 amino acids (tyrosine, phenylalanine, tryptophan) on a 4, 5-imidazoledicarboxylic acid-modified organo-silica hybrid monolithic column, it can be seen that 3 aromatic amino acids obtained a more satisfactory separation on the hybrid monolithic column, and at the same time, compared to the separation obtained on an imidazole-1-acetic acid-modified organo-silica hybrid monolithic column (except that an excess of 100 mg/m L in terms of aqueous imidazole-1-acetic acid was used, which was the same as in example 1), the aromatic amino acids obtained on a 4, 5-imidazoledicarboxylic acid-modified organo-silica hybrid monolithic column as shown in a of FIG. 3C, resulted in a more efficient separation.
The performance of the monolithic column under reverse phase chromatography conditions for separating different types of polar compounds was examined. In general, acidic compounds are difficult to achieve good separation in reverse phase chromatography mode, primarily because the analyte migrates in a direction opposite to that of the electroosmotic flow, and may not be eluted. FIG. 4A shows the electrochromatography separation of 3 common benzoic acid derivatives (p-hydroxybenzoic acid, p-aminobenzoic acid, benzoic acid) on a 4, 5-imidazole dicarboxylic acid modified organo-silica gel hybrid monolithic column. As can be seen from the figure, 3 benzoic acid derivatives gave baseline separations under either water-rich or reverse phase chromatographic conditions. However, we have found that the column efficiency of the benzoic acid derivative increases with increasing acetonitrile content in the mobile phase, which indicates that increasing acetonitrile content in the mobile phase will facilitate achieving better separation of the benzoic acid derivative. Therefore, the benzoic acid derivative can obtain better separation effect under the condition of reverse phase chromatography. FIG. 4B shows the chromatographic separation of 3 phenolic compounds (hydroquinone, phenol, p-cresol) on a 4, 5-imidazoledicarboxylic acid-modified organo-silica gel hybrid monolithic column. As can be seen from the figure, 3 phenolic compounds were efficiently separated under reverse phase chromatographic conditions.
As can be seen from fig. 3 and 4, the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column has good separation performance for different types of polar compounds, and can be applied to separation analysis of different types of polar compounds in different chromatographic modes.
The items used in the present invention examples 1 to 10 and in the monolithic column parameter characterization and chromatography performance examination are shown in table 1.
Although the specific embodiments of the present invention have been described with reference to the examples, the scope of the present invention is not limited thereto, and those skilled in the art will appreciate that various modifications and variations can be made without inventive effort by those skilled in the art based on the technical solution of the present invention.
Claims (1)
1. The application of the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column in the separation and analysis of polar compounds is characterized in that: the preparation of the organic-silica gel hybrid monolithic column comprises the following steps:
(a) selecting tetramethoxysilane and chloropropyltrimethoxysilane as precursors, and preparing a chloropropyl-silica hybrid silica monolithic column bed by a sol-gel method;
(b) washing the chloropropyl-silica gel hybrid silica gel monolithic column bed by using an excessive ammonia water solution of 4, 5-imidazole dicarboxylic acid, and then placing the chloropropyl-silica gel hybrid silica gel monolithic column bed in a thermostat for reaction to obtain the 4, 5-imidazole dicarboxylic acid modified organic-silica gel hybrid monolithic column;
in the step (a), the preparation method of the chloropropyl-silica gel hybrid monolithic column bed comprises the steps of dissolving polyethylene glycol in an acetic acid aqueous solution, adding Tetramethoxysilane (TMOS) and Chloropropyltrimethoxysilane (CPTMS) into the acetic acid aqueous solution to obtain a mixed solution, placing the mixed solution in an ice water bath condition for reaction until a uniform and transparent sol is formed, performing ultrasonic treatment on the sol under the ice water bath condition, introducing the sol into a treated capillary tube, sealing two ends of the capillary tube by using silicone grease, placing the capillary tube in a thermostat for reaction, and completing a gel process to obtain the chloropropyl-silica gel hybrid monolithic column bed, wherein the dosage ratio of the polyethylene glycol, the tetramethoxysilane and the chloropropyltrimethoxysilane is 240 mg: 0.9m L: 0.3m L, the reaction time of the mixed solution under the ice water bath condition is 3-5 hours, and the ultrasonic time under the ice water bath condition is 3-5 minutes;
the treated capillary tube is obtained by the following steps of taking a fused quartz capillary tube, sequentially washing the fused quartz capillary tube with methanol and distilled water for 20min, sequentially washing the fused quartz capillary tube with 1 mol/L NaOH solution, water and 1 mol/L hydrochloric acid for 2.0h, 0.5h and 1.5h, washing the fused quartz capillary tube with water until the pH of the washed liquid is neutral, finally washing the fused quartz capillary tube with methanol for 20min, and drying the fused quartz capillary tube with nitrogen at 120 ℃;
in the step (b), the concentration of the ammonia water solution of the 4, 5-imidazole dicarboxylic acid is more than or equal to 30mg/m L, and the reaction conditions of placing the chloropropyl-silica gel hybrid silica gel monolithic column bed in a thermostat are that the reaction temperature is 60-80 ℃ and the reaction time is 23-25 hours;
the polar compound is selected from amide compounds, nucleoside and nucleoside base, amino acid, benzoic acid derivative and phenolic compounds; the amide compound is selected from formamide, N, N-dimethylformamide, N, N-dimethylacetamide and caprolactam; said nucleoside and nucleoside bases are selected from uridine, inosine, thymidine, hypoxanthine; the amino acid is selected from tyrosine, phenylalanine, tryptophan; the benzoic acid derivative is selected from p-hydroxybenzoic acid, p-aminobenzoic acid, benzoic acid; the phenolic compound is selected from hydroquinone, phenol and p-cresol.
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