阅读说明：本技术 以金属丝为模板的硅胶整体开管毛细管柱及其制备方法 (Silica gel integral open-tube capillary column with metal wire as template and preparation method thereof ) 是由 蒋晨 陆波 王亚娟 朱昌青 于 2020-07-10 设计创作，主要内容包括：本发明公开了一种以金属丝为模板的硅胶整体开管毛细管柱及其制备方法,该制备方法包括：1)将金属丝引入第一毛细管中作为模板,接着将溶胶溶液灌装至毛细管中,然后将第一毛细管的两端进行封端；2)将毛细管进行热处理,再进行程序升温处理,接着将模板脱除,然后依次对第一毛细管进行清洗、干燥和煅烧,以制得硅胶整体开管毛细管柱；其中,溶胶溶液包括聚乙二醇、尿素、正硅酸甲酯、醋酸溶液。该制备方法能够使得开管毛细管柱内的硅胶分布均匀且较厚,同时使得该开管毛细管柱不易堵塞。(The invention discloses a silica gel integral open-tube capillary column taking a metal wire as a template and a preparation method thereof, wherein the preparation method comprises the following steps: 1) introducing a metal wire into a first capillary tube to serve as a template, filling a sol solution into the capillary tube, and then sealing two ends of the first capillary tube; 2) carrying out heat treatment on the capillary tube, carrying out temperature programming treatment, removing the template, and then sequentially cleaning, drying and calcining the first capillary tube to obtain a silica gel integral open-tube capillary column; wherein the sol solution comprises polyethylene glycol, urea, methyl orthosilicate and acetic acid solution. The preparation method can ensure that the silica gel in the open-tube capillary column is uniformly distributed and thicker, and simultaneously the open-tube capillary column is not easy to block.)

1. A preparation method of a silica gel integral open-tube capillary column taking a metal wire as a template is characterized by comprising the following steps:

1) introducing a metal wire into a first capillary tube to serve as a template, filling a sol solution into the capillary tube, and then sealing two ends of the first capillary tube;

2) carrying out heat treatment on the capillary tube, carrying out temperature programming treatment, removing the template, and then sequentially cleaning, drying and calcining the first capillary tube to obtain the silica gel integral open-tube capillary column;

wherein the sol solution comprises polyethylene glycol, urea, methyl orthosilicate and acetic acid solution.

2. The preparation method according to claim 1, wherein the ratio of the polyethylene glycol, urea, methyl orthosilicate and acetic acid solution in the sol solution is 0.104-0.144 g: 0.08-0.10 g: 300-500. mu.L: 0.8-1.5 mL;

preferably, the preparation of the sol solution comprises the steps of: stirring polyethylene glycol, urea and acetic acid solution for 8-10min under ice bath condition, adding methyl orthosilicate ice, stirring for 30-50min, and oscillating for 8-10min under ice bath and 40-60KHz ultrasonic condition;

preferably, the polyethylene glycol is selected from at least one of PEG-400, PEG-2000, PEG-4000, PEG-10000 and PEG-20000;

preferably, the pH of the acetic acid solution is 1-5.

3. The production method according to claim 1 or 2, wherein the end-capping employs dropping an end-capping material at both ends of the first capillary;

preferably, the end-capping compound is silicone rubber;

preferably, the amount of the end caps at both ends of the first capillary is 1 to 2 drops.

4. The production method according to claim 1 or 2, wherein, prior to the end-capping, step 1) further comprises positioning the wire with both ends of the wire located outside the first capillary; the second capillary is funnel-shaped; the positioning includes: introducing one end of the metal wire into the narrow-mouth end from the wide-mouth end of the second capillary tube, so that one end of the metal wire is fixed in the narrow-mouth end, and meanwhile, the wide-mouth end is sleeved outside one end of the first capillary tube;

preferably, the first capillary is a chromatography column capillary and the second capillary is a spotting capillary;

preferably, the outer diameter of the first capillary is 355-375 μm, and the maximum inner diameter of the wide-mouth end is 5-10 μm larger than the outer diameter of the first capillary;

preferably, the inner diameter of the narrowest part of the narrow-mouth end is 2-5 μm larger than the diameter of the metal wire.

5. The production method according to claim 1 or 2, wherein the inner diameter of the first capillary is 55 to 75 μm;

preferably, the diameter of the wire is 25-50 μm;

preferably, the metal wire is selected from one of a gold wire and a platinum wire.

6. The production method according to claim 1 or 2, wherein, in step 2), the heat treatment satisfies at least the following condition: the temperature is 30-50 ℃, and the time is 11-16 h;

preferably, the heat treatment is carried out in a water bath.

7. The production method according to claim 1 or 2, wherein, in step 2), the temperature-raising treatment satisfies the following condition: heating from 50 ℃ to 110-130 ℃ at the speed of 15-25 ℃/h, and preserving the heat for 2.5-3.5 h;

preferably, the cleaning comprises: washing with high purity water and methanol for 2-3 times.

8. The production method according to claim 1 or 2, wherein, in step 2), the drying satisfies at least the following condition: the temperature is 50-70 ℃, and the time is 6-8 h;

preferably, the calcination at least satisfies the following condition: the temperature is 320-380 ℃ and the time is 4-6 h.

9. The production method according to claim 1 or 2, wherein the template removal includes: completely cutting off one end of the first capillary, and performing circular cutting on the other end without cutting off the metal wire; then drawing outwardly from one end of the circular cut to remove the template from the first capillary;

preferably, said template removal is performed after said first capillary has cooled;

preferably, before step 1), the preparation method further comprises: respectively performing ultrasonic treatment on the metal wire in high-purity water and ethanol for 8-10min, and then drying; washing the first capillary tube for 4-6h at 50-60 ℃ sequentially by using a sodium hydroxide solution with the concentration of 1-2mol/L, a hydrochloric acid solution with the concentration of 0.1-0.2mol/L, high-purity water and acetone;

more preferably, the sol solution is filtered through a 0.45 μm needle filter while the sol solution is being filled.

10. A silica gel monolithic open tubular capillary column using a metal wire as a template, which is prepared by the preparation method of any one of claims 1 to 9.

Technical Field

The invention relates to a capillary column, in particular to a silica gel integral open-tube capillary column taking a metal wire as a template and a preparation method thereof.

Background

Chromatography is a physical separation method in which a mixture of components is dispersed between two phases, one being a Stationary Phase (SP) enclosed in a tube and the other being a Mobile Phase (MP) passing in a certain direction through the tube. Miniaturized instruments and green chemistry are two very important topics in modern analytical science, both of which affect the future development of chromatography, reflected in the current demand for portable instruments and the reduction of solvent consumption. Chromatographic columns in the form of capillary columns of 5-500 μm internal diameter have attracted research interest in the field due to the reduced sample volume requirements and greatly reduced solvent consumption.

Capillary chromatography columns generally take three forms, namely: fill, bulk and open tube. Among them, open-tube (OT) columns generally exhibit the advantages of higher column efficiency, lower column pressure, no need of complex frit fabrication, less formation of bubbles, etc., and have been widely used in the fields of liquid chromatography, capillary electrophoresis, open-tube capillary electrochromatography, micro solid-phase extraction, etc.

The open tubular column stationary phase can be divided into a physical adsorption stationary phase and a chemical bonding stationary phase. The physical adsorption stationary phase is combined on the inner wall of the capillary through electrostatic, hydrophobic or non-specific combination interaction, and the preparation process is simple. And the chemically bonded stationary phase is attached to the inner wall of the capillary tube through a covalent bond, so that the stability and the durability are higher. In order to improve the retention value and the column capacity of the open tubular column, the porous layer open tubular capillary column is produced, wherein the porous silicon layer open tubular capillary column can further improve the specific surface area, the mechanical property and the swelling resistance of the stationary phase.

There are two trends in open columns, one is towards narrow diameter, which has outstanding peak capacity, but at the expense of high back pressure, very long analysis times, even at nano (or even slight) flow rates, in some cases even up to several hours, and the need to deploy highly sensitive detectors. The other one is the development towards the wide diameter of more than or equal to 20 mu m, and the wide-diameter open-tube capillary column with a certain stationary phase thickness mainly has the advantages of low back pressure, short analysis time, high capacity, high retention value and the like, and has important significance for the fields of low-pressure separation, micro solid-phase extraction, immobilized enzyme and the like. The ratio of the inner diameter of the capillary to the thickness of the stationary phase should be less than or equal to 100 for proper chromatographic retention, so that a wider tube diameter means that a thicker stationary phase is required.

At present, wide-diameter polymer porous layer open-tube capillary columns have been successfully prepared and widely used. However, in the capillary with larger tube diameter (not less than 20 μm), the problems that the silica sol is easily blocked by the capillary due to the influence of gravity, the stationary phase is unevenly distributed, the preparation of thicker fixed phase is difficult, and the like exist.

Disclosure of Invention

The invention aims to provide a silica gel integral open-tubular capillary column taking a metal wire as a template and a preparation method thereof, and the preparation method can ensure that silica gel in the open-tubular capillary column is uniformly and thickly distributed and the open-tubular capillary column is not easy to block.

In order to achieve the above object, the present invention provides a method for preparing a silica gel integral open-tubular capillary column using a metal wire as a template, the method comprising:

1) introducing a metal wire into a first capillary tube to serve as a template, filling a sol solution into the capillary tube, and then sealing two ends of the first capillary tube;

2) carrying out heat treatment on the capillary tube, carrying out temperature programming treatment, removing the template, and then sequentially cleaning, drying and calcining the first capillary tube to obtain a silica gel integral open-tube capillary column;

wherein the sol solution comprises polyethylene glycol, urea, methyl orthosilicate and acetic acid solution.

The invention provides a silica gel integral open-tubular capillary column taking a metal wire as a template, which is prepared by the preparation method.

In the technical scheme, metal filaments are introduced into the capillary by a template method, so that the prepared silica gel capillary column with the integrally opened tube has a porous silicon layer stationary phase, and the column can form a regular through-hole channel; and the thickness of the split-tube column stationary phase can be controllably adjusted in the modes of stationary phase shrinkage, template size, capillary inner diameter and the like.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is an SEM of a production string made in example 1-2;

FIG. 2 is an SEM of a production string made in examples 1 and 3;

FIG. 3 is an SEM of a production string made in examples 1 and 4;

FIG. 4 is an SEM of a production string made in examples 1 and 5;

FIG. 5 is an SEM of a production string made in examples 1 and 6;

FIG. 6 is an SEM of a production string made in example 7;

FIG. 7 is an SEM of a production string made in example 8;

FIG. 8 is an SEM of a production string made in example 9;

FIG. 9-1 is a nitrogen adsorption-desorption isotherm of the stationary phase of detection example 1;

FIG. 9-2 is a pore size distribution diagram of the stationary phase of detection example 1;

FIG. 10-1 is a nitrogen adsorption-desorption isotherm of the stationary phase of detection example 2;

FIG. 10-2 is a pore size distribution diagram of the stationary phase of detection example 2;

FIG. 11-1 is a nitrogen adsorption-desorption isotherm of the stationary phase of detection example 3;

FIG. 11-2 is a pore size distribution diagram of the stationary phase of detection example 3;

FIG. 12 is a schematic diagram of the processing step of the second capillary and the positioning step of the wire in the present invention.

Description of the reference numerals

1. Capillary original tube 2, second capillary

3. First capillary 4, wire

5. Wide mouth end 6, narrow mouth end

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a preparation method of a silica gel integral open-tube capillary column by taking a metal wire as a template, which comprises the following steps:

1) introducing a metal wire into a first capillary tube to serve as a template, filling a sol solution into the capillary tube, and then sealing two ends of the first capillary tube;

2) carrying out heat treatment on the capillary tube, carrying out temperature programming treatment, removing the template, and then sequentially cleaning, drying and calcining the first capillary tube to obtain a silica gel integral open-tube capillary column;

wherein the sol solution comprises polyethylene glycol, urea, methyl orthosilicate and acetic acid solution.

In the above preparation method, the content of each component in the sol solution can be selected within a wide range, but in order to further optimize the shrinkage rate, mechanical strength and porosity of the stationary phase of the integrated open capillary column, it is preferable that the ratio of the polyethylene glycol, urea, methyl orthosilicate and acetic acid solution in the sol solution is 0.104-0.144 g: 0.08-0.10 g: 300-500. mu.L: 0.8-1.5 mL; more preferably 0.122 to 0.126 g: 0.08-0.10 g: 350-450 μ L: 0.8-1.5 mL.

Among the above preparation methods, the preparation method of the sol solution may be selected within a wide range, but in order to further optimize the shrinkage rate, mechanical strength and porosity of the stationary phase of the integrated open capillary column, and at the same time, in order to avoid gelation of the sol solution; preferably, the preparation of the sol solution comprises the following steps: stirring polyethylene glycol, urea and acetic acid solution for 8-10min under ice bath condition, adding methyl orthosilicate ice, stirring for 30-50min, and shaking for 8-10min under ice bath and 40-60KHz ultrasonic condition.

In the present invention, the kind of the polyethylene glycol can be selected within a wide range, but in order to further optimize the shrinkage rate, mechanical strength and porosity of the stationary phase of the integrated open capillary column, preferably, the polyethylene glycol is selected from at least one of PEG-400, PEG-2000, PEG-4000, PEG-10000 and PEG-20000; more preferably, the polyethylene glycol is selected from PEG-10000.

In the present invention, the pH of the acetic acid solution can be selected within a wide range, but to further optimize the shrinkage, mechanical strength and porosity of the stationary phase of the integrated open-tube capillary column, the pH of the acetic acid solution is 1-5; more preferably, the pH of the acetic acid solution is 3-4.

In the present invention, in order to ensure that both ends of the first capillary are completely closed, it is preferable that the end-capping is performed by dropping an end-capping material on both ends of the first capillary; preferably, the end-cap is a silicone rubber; preferably, the amount of the end caps at both ends of the first capillary is 1-2 drops (the silicone rubber is in a semi-solid state at the time of dropping).

In addition, in order to prevent the sol solution from being gelled or contaminated, it is preferable that the temperature of the wire from the introduction into the first capillary to the capping is 0 to 25 ℃ and the time is controlled within 30 min.

In the present invention, in order to ensure that the wire 4 is in the middle position of the first capillary 3, preferably, as shown in step e of fig. 12, before the end-capping, step 1) further includes positioning the wire, both ends of the wire 4 are located outside the first capillary 3; the second capillary 2 is funnel-shaped; the positioning includes: and introducing one end of the metal wire 4 into the narrow end 6 from the wide end 5 of the second capillary 2, so that one end of the metal wire 4 is fixed in the narrow end 6, and meanwhile, the wide end 5 is sleeved outside one end of the first capillary 3.

The processing method of the second capillary may be selected from a wide range, but in order to consider the difficulty of processing, as shown in steps a to d of fig. 12, the processing method of the second capillary is: the capillary original tube 1 is vertically placed, a pipette tip with 20 mu L is sleeved at the lower end of the capillary original tube (the capillary original tube 1 is vertically pulled downwards, the middle part is naturally pulled downwards after being heated and softened, so that the middle part becomes thin), the middle part of the capillary original tube 1 is burnt, and glass is heated and softened and naturally pulled downwards. The burned sample application capillary is gradually reduced in inner diameter and cut off by a capillary cutter at a position where the metal filament 4 cannot penetrate for standby.

In the present invention, the kind of the first capillary and the second capillary may be selected from a wide range, but it is preferable that the first capillary is a column capillary and the second capillary is a spot capillary in view of convenience of handling and strength.

In the present invention, the sizes of the first capillary and the second capillary can be selected in a wide range, but in order to facilitate the fixation of the wire 4, it is preferable that the outer diameter of the first capillary is 355 and 375 μm, and the maximum inner diameter of the wide-mouth end is 5-10 μm larger than the outer diameter of the first capillary; preferably, the inner diameter of the narrowest part of the narrow-mouth end is 2-5 μm larger than the diameter of the wire.

Further, in the above preparation method, in order to facilitate the regulation of the thickness of the stationary phase, it is preferable that the inner diameter of the first capillary is 55 to 75 μm; more preferably, the diameter of the wire is 25-50 μm. Still further preferably, the diameter of the template is 50 μm and the inner diameter of the first capillary is 75 μm.

In the present invention, the kind of the wire may also be selected within a wide range, but is convenient for operation; preferably, the metal wire is selected from one of a gold wire and a platinum wire.

In step 2) of the above preparation method, specific conditions of the gelation reaction may be selected within a wide range, but in order to improve the mechanical strength and uniformity of the stationary phase, it is preferable that in step 2), the heat treatment satisfies at least the following conditions: the temperature is 30-50 ℃, and the time is 11-16 h; more preferably, the heat treatment is carried out in a water bath.

In the present invention, the process of temperature programming can be adjusted within a wide range, but in order to obtain a homogeneous stationary phase in a short time, it is preferable that, in step 2), the temperature raising treatment satisfies the following conditions: heating from 50 ℃ to 110-130 ℃ at the speed of 15-25 ℃/h, and preserving the heat for 2.5-3.5 h;

in the present invention, the manner of washing may be adjusted within a wide range, but in order to make the inside of the column clean and dry, it is preferable that the washing includes: washing with high purity water and methanol for 2-3 times.

In the present invention, the conditions for drying may be adjusted within a wide range, but in order to make the inside of the column clean and dry, it is preferable that in step 2), the drying satisfies at least the following conditions: the temperature is 50-70 ℃ and the time is 6-8 h.

In the present invention, the conditions of calcination may be adjusted within a wide range, but in order to improve the mechanical strength and porosity of the stationary phase, it is preferable that calcination satisfies at least the following conditions: the temperature is 320-380 ℃ and the time is 4-6 h.

In the present invention, the mode of template removal can be selected in a wide range, but for better morphology of the stationary phase, the template removal preferably comprises: completely cutting off one end of the first capillary, and performing circular cutting on the other end without cutting off the metal wire; and then pulled outwardly from the end of the circular cut to remove the template from the first capillary.

In the present invention, the timing of template removal can be selected within a wide range, but for better morphology of the stationary phase, it is preferable that the template removal is performed after the first capillary is cooled.

In the present invention, in order to enable the prepared stationary phase to have higher cleanliness, better stability and durability, it is preferable that the preparation method further comprises, before step 1): respectively performing ultrasonic treatment on the metal wire in high-purity water and ethanol for 8-10min, and then drying; washing the first capillary tube for 4-6h at 50-60 ℃ sequentially by using a sodium hydroxide solution with the concentration of 1-2mol/L, a hydrochloric acid solution with the concentration of 0.1-0.2mol/L, high-purity water and acetone; the pretreatment means can ensure that enough silicon hydroxyl groups can be exposed on the inner wall of the capillary tube to react with the immobilized phase.

In the present invention, in order to prevent the sol solution from having large particulate matter, it is preferable that the sol solution is filtered through a 0.45 μm needle filter while the sol solution is filled.

The invention provides a silica gel integral open-tubular capillary column taking a metal wire as a template, which is prepared by the preparation method.

The present invention will be described in detail below by way of examples. In the following examples, SEM scans were taken by a scanning electron microscope (S8100) from hitachi, japan; the nitrogen adsorption-desorption curve pore size distribution was measured by a nitrogen adsorption-desorption tester (ASAP-2460) of Michmi instruments, USA.

Medicine preparation: tetraethoxysilane is Demas-beta brand which is a pure analytical product; the product of polyethylene glycol is a national medicine group reagent company with a brand of analytical purity; the product of the national drug group reagent company Limited is urea; glacial acetic acid is a national medicine group reagent company, and the brand is analytical grade.

The positioning operation of the wire is: the two ends of the metal wire 4 are positioned outside the capillary tube of the chromatographic column; the second capillary 2 is funnel-shaped; and introducing one end of the metal wire 4 into the narrow end 6 from the wide end 5 of the second capillary 2, so that one end of the metal wire 4 is fixed in the narrow end 6, and meanwhile, the wide end 5 is sleeved outside one end of the chromatographic column capillary.

The template removing operation is as follows: completely cutting off one end of the chromatographic column capillary, and performing circular cutting on the other end without cutting off the metal wire; the ring cut end is then pulled outward to remove the template from the capillary of the column.

Preparation example 1

As shown in a-d of FIG. 12, spotting capillaries of various specifications were placed vertically, and 20. mu.L of pipette tips were fitted over the lower end of the spotting capillaries, and the center of the spotting capillary was burned, and the glass was softened by heat and naturally pulled down. The burned sample application capillary is gradually reduced in inner diameter, and is cut off by a capillary cutter at a position where the metal filament 4 cannot penetrate, so as to form second capillaries with various specifications.