JP4521754B2 - Capillary tube and manufacturing method thereof - Google Patents

Description

  The present invention relates to a capillary tube obtained by chemically bonding a compound having a polar group to a silanol group on the inner wall surface of a fused silica glass capillary tube and a method for producing the same.

Capillary electrophoresis (hereinafter sometimes referred to as CE) is a general term for electrophoresis performed in a capillary tube having an inner diameter of 100 μm or less, and is a separation analysis method useful for separation of ionic compounds. In CE, separation is performed by mobility based on the charge, ionicity, ion radius, and the like of a sample in a homogeneous phase. By using a capillary tube, CE can solve the following problems in ordinary electrophoresis. That is, even when a very high electric field of about 100 to 500 Vcm ⁻¹ is applied, the flowing current is small, the generation of Joule heat can be minimized, and the capillary has a surface area ratio to the internal volume. Since it is large, the generated Joule heat can be efficiently dissipated. Furthermore, CE has super high resolution of 10 ⁵ to 10 ⁷ theoretical plates, high-speed analysis, simultaneous analysis of anionic, cationic and nonionic compounds, and a small sample amount of about 1 to 10 nl. It is possible to analyze both of aqueous and non-aqueous solvents, and has superior features and advantages not found in any conventional electrophoresis method capable of capillary on-line detection. Using these characteristics, CE is applied in a wide range of fields such as analysis and measurement of environmental samples, foods, drugs and the like. In addition, the micellar electric chromatography combining the principle of CE and chromatography is also applied to the separation of nonionic compounds using micelles.

  Furthermore, a technique called capillary electrochromatography (hereinafter sometimes referred to as CEC) in which capillary electrophoresis and HPLC (high performance liquid chromatography) are fused is also performed. CEC is liquid chromatography performed in an electric field by applying a voltage, and the analyte moves in a flow by a pump and an electroosmotic flow (hereinafter sometimes referred to as EOF). The capillaries used in this method are 500 μm I.D. slightly thicker than CE for the convenience of filling with the filler. D. Something about is widely used.

  For analysis of conventional general CE or CEC, a fused silica hollow capillary with an untreated inner wall surface is used, and CE using such a hollow capillary is capillary zone electrophoresis (hereinafter sometimes referred to as CZE). being classified. This inner wall untreated fused silica hollow capillary tube has polar silanol groups on the inner wall, the electroosmotic flow depends on the dissociation of silanol groups, and the lower the pH of the electrophoresis solution, the more the dissociation of silanol groups is suppressed. , EOF has the disadvantage that it is slow and the analysis time is long. Therefore, it is difficult to use in the acidic region. Further, at a high pH value, there is a drawback that the chemical stability is lacking, and further, the silanol group dissociation is unstable, so that the reproducibility of the EOF value is low. As a solution, a capillary tube made of a plastic material and having a hydrophilic substance bonded to the inner wall is provided. (Patent Document 1)

  However, because it is made of plastic material, it is weak against heat generated by applying voltage, and further, the application range such as the type and concentration of organic solvent used in the case of electrochromatography is limited. was there. In addition, there is a drawback that it is very difficult to stably control the inner diameter of the capillary tube as a separation field.

  A capillary tube in which an ionic polymer is adsorbed on the inner wall has also been proposed (Patent Document 2). This is a physical coating of an ionic polymer on the inner wall of the capillary. The effect of silanol on the capillary surface is reduced, and EOF is faster than that of an untreated capillary tube under acidic conditions. There is a problem that the analysis time is slow, the analysis time is long, and the migration time does not have high reproducibility. The migration time means the time required for the solute to move to the detector, that is, the movement time, and is an important factor for calculating the measured mobility. The cause of the above-described defects when coating with an ionic polymer is considered as follows. That is, the functional group is not bonded to each silanol on the capillary surface, and the whole is coated so as not to be affected by silanol. Therefore, it is considered that unreacted silanol is inevitably present. Therefore, it is considered that silanol is easily dissociated in the neutral region, and the influence thereof has an influence on actual electrophoresis. Further, since the dissociation of the polar groups contained therein does not occur uniformly due to the influence of the film thickness of the polymer coat, it is conceivable that the polar groups do not act effectively.

Japanese Unexamined Patent Publication No. 7-225218 Japanese Patent No. 3355393 Patent Publication

  Therefore, the present invention solves the above-mentioned problems in capillary tubes used for CE, CEC, etc., and shortens the analysis time and separation by increasing the electroosmotic flow without adding additives to the electrophoresis solution or increasing the electric field. The purpose is to increase efficiency and resolution and to have chemical stability. In addition, it can be used in a wide range from acidic to basic, and the EOF value does not change even when the pH of the electrophoresis solution is changed, and the reproducibility of migration time is high, especially at pH = 4-8. Even when a neutral substance is separated by adding a surfactant to the electrophoresis solution, the object is to provide reproducibility with a high migration time. Another object of the present invention is to broaden the application range of the type and concentration of the organic solvent used at the time of analysis and to stably control the inner diameter of the capillary tube. Furthermore, it does not require storage in which a preservation solution is injected, and can be handled easily, and can be post-treated with an organic solvent, an acidic or alkaline solution and a surfactant in the production process, and is applied to the inner wall. The purpose is to provide high reproducibility from the beginning of use by maintaining the polarity in the water and removing the salt.

In order to solve the above-mentioned problems, first, the present invention provides a stable dissociation by first chemically bonding a compound having a polar group for adding a surface charge and a reactive group to a silanol group on the inner wall surface of a fused silica glass capillary tube. The capillary tube is characterized in that the inner wall surface has a property .

  Second, in the first capillary tube, the capillary tube is a capillary tube used for electrophoresis or a capillary tube for electrochromatography.

Thirdly, in the first capillary tube, the capillary tube is a capillary tube, characterized in that the connection pipe and the mobile phase liquid.

Fourth, in any of the first to third capillary tubes, the compound having a polar group has a polar group that increases the surface charge on the inner wall surface of the capillary tube and an inorganic metal bonded to the reactive group. A capillary tube characterized by being an organic monomer.

  Fifth, in the fourth capillary tube, the inorganic metal is a capillary tube selected from the group consisting of silicon, titanium and zirconium.

Sixth, in any one of the first to fifth capillary tubes, the polar group of the organic monomer is chemically bonded to the inner wall surface and is a polar group having a high surface charge, a sulfone group, a carboxyl group, a cyano group, It is a capillary tube that is at least one of a quaternary ammonium group, a primary to tertiary amino group, and a trifluoro group.

Seventh, it is characterized in that a compound having a polar group for adding surface charge and a reactive group is chemically bonded to a silanol group on the inner wall surface of a fused silica glass capillary tube to form a stable dissociating inner wall surface. This is a method of manufacturing a capillary tube.

Eighth, in the seventh method for producing a capillary tube, after chemically bonding, the organic solvent or / and acidic solution or / and alkaline solution or / and a surfactant are used for the reaction by-product. Or capillary group re-dissociation treatment .
Ninth, the capillary tube manufacturing method is characterized in that the seventh and eighth chemical bonds are washed and dried.

  According to the present invention as described above, the electroosmotic flow can be accelerated without adding an additive to the electrophoresis solution or increasing the electric field, and the analysis time can be shortened. In addition, chemical stability was improved with respect to all of acidic solution, alkaline solution and organic solvent. That is, even if these solvents are used, the chemical modification is not easily cleaved. Moreover, the capillary tube obtained by chemically modifying a compound having a polar group on the inner wall surface has a high theoretical plate number, extremely high separation efficiency and separation ability, and can exhibit a remarkable effect in separation analysis.

  Furthermore, it can be used in a wide range from acidic to basic, and the EOF value does not change even when the pH of the electrophoresis solution is changed, and the reproducibility of the migration time is high, particularly at pH = 4-8. Even when a neutral substance is separated by adding a surfactant to the electrophoresis solution, it is possible to provide reproducibility with a high migration time. In addition, it is possible to expand the application range of the type and concentration of the organic solvent used at the time of analysis. In addition, the inner diameter of the capillary tube can be stably controlled. Furthermore, it does not require storage with the storage solution injected, and can be handled easily, and can be washed with an organic solvent, acidic or alkaline solution and surfactant in the manufacturing process, and has a polarity on the inner wall. It became possible to have high reproducibility from the beginning of use by maintaining the water and removing the salt.

  Hereinafter, embodiments of the present invention will be described in detail. The capillary tube according to the present invention is mainly used as a capillary tube used for capillary electrophoresis, a capillary tube for capillary electrochromatography, etc., and can also be applied to CE / MS (mass spectrometry). Furthermore, it can also be applied to capillary connection pipes that use liquid as the mobile phase. Examples of connection pipes include HPLC sample loops, HPLC and MS connection pipes, HPLC mutual connection pipes, and MS infusion analysis. Piping to be used. The material of the capillary tube is fused silica glass, and the inner diameter is not particularly limited, but a material of about 25 to 500 μm is mainly used depending on the application.

As the compound having a polar group in the present invention, a compound that can be dissolved in an organic solvent such as dichloromethane or toluene can be used. The compound is preferably a compound containing an inorganic metal such as silicon, titanium and zirconium bonded to a reactive group, and silicon is particularly preferable as the inorganic metal. This is because the inner wall of a fused silica glass capillary tube has a siloxane bond, and a compound containing silicon (silylating agent) is highly reactive and can be treated with an appropriate functional group. Further, it is convenient to use —OCH ₃ , Cl or the like as the reactive group bonded to the inorganic metal. When there is only one reactive moiety, it is efficient because it can be bonded to a silanol group on a one-to-one basis. However, in a compound having a reactive group at two or more locations, the compounds are combined to form an oligomer. Since there is a possibility, it is actually necessary to adjust the experimental conditions and combine them.

  In addition, as a polar group, at least one group among a sulfone group, a substituent having an ester structure, a cyano group, a quaternary ammonium group, a primary to tertiary amino group, a trifluoro group, and the like can be used. You may have two or more types and / or two or more polar groups in the compound. An organic monomer can be used as the compound having a polar group. Specific examples include trichlorosilane and trialkoxysilane containing polar groups such as sulfone group, carboxyl group, cyano group, quaternary ammonium group, primary to tertiary amino group, and trifluoro group.

  More specifically, N- (2-diaminoethyl) -3-propyltrimethoxysilane, aminophenoxydimethylvinylsilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropylmethylbis (trimethylsiloxy) silane as a silylating agent, 3-aminopropylpentamethyldisiloxane, 3-aminopropylsilanetriol, bis (P-aminophenoxy) dimethylsilane, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, bis (3-cyanopropyl) dimethoxy Lan, bis (cyanopropyl) tetramethyldisiloxane, bis (dimethylamino) dimethylsilane, bis (dimethylamino) vinylmethylsilane, bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 2- (4- Lorossulfonylphenyl) ethyltrimethoxysilane, 2- (4-chlorosulfonylphenyl) ethyltrichlorosilane, (3-cyanobutyl) trichlorosilane, 2-cyanoethyltrimethoxysilane, 3-cyanopropyl (diisopropyl) dimethylaminosilane, 3-cyano Propyldimethylchlorosilane, 3-cyanopropylmethylcyclosilazane, 3-cyanopropylphenyldichlorosilane, (aminoethylaminomethyl) phenethyltrimethoxysilane, (pentadecafluoro-1,1,2,2-tetrahydrodecyl) dimethylchlorosilane, (Pentadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane, 3- (pentafluoroisopropoxy) propyltriethoxysilane, N-methylamino Propyltriethoxysilane, pentafluorophenyldimethylchlorosilane, pentafluorophenylpropyltrimethoxysilane, tetrakis (diethylamino) silane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) methyldichlorosilane, (tridecafluoro- 1,1,2,2-tetrahydrooctyl) trichlorosilane, 3- (3,3,3-trifluoropropyl) heptamethyltrisiloxane, (3,3,3-trifluoropropyl) trichlorosilane, tris (dimethylamino) ) Chlorosilane, tris (dimethylamino) silane, vinyl (trifluoromethyl) dimethylsilane and the like can be used.

  In addition, it is possible to use the above compound in which silicon or titanium is replaced with titanium or zirconium. These compounds are usually used alone, but may be used in combination.

  In order to produce the capillary according to the present invention, for example, a compound having a polar group dissolved in an organic solvent is passed through a capillary tube made of fused silica glass and heated. Thereafter, it can be produced by washing, that is, post-treatment with an organic solvent such as dichloromethane, methanol or acetone, an acidic solution such as phosphoric acid, an alkaline solution or a surfactant. These solvents, solutions, and the like may be used alone for post-treatment, but a plurality of types may be used. Washing with phosphoric acid can also be performed with other acidic solutions such as acetic acid.

  On the other hand, the oligomer produced during the chemical modification has a weaker bond with the capillary surface than that of the single phase, and therefore can be removed by the washing step, that is, the post-treatment described in the present invention. The washing step is an effective means for producing a capillary with good reproducibility. That is, organic solvent cleaning is effective for removing the oligomer. In addition, polar groups that contribute to reproducibly adjusting the EOF time may lose their useful polarity due to dehydration by heating or the like when introducing chemical species. In that case, the polarity can be restored by adding water or the like by post-treatment with a solution having acidity or alkalinity. In addition, the polar group may be effective when it contains a salt. However, in actual use, it may take a long time from the start of use, and in the manufacturing process, the post-treatment as described above may be performed to remove the salt. If you keep it, you can use it immediately. That is, high reproducibility can be obtained from the beginning of use.

  Hereinafter, the present invention will be described in more detail with reference to examples of capillary tubes in which a compound having a polar group on the inner wall surface is chemically modified. However, the present invention is not limited thereto.

First, 0.05 mm I.D. made of fused silica glass is used. D. Pass a 0.5 ml 2- (4-chlorosulfonylphenyl) ethyltrichlorosilane 50% toluene solution through a capillary tube of 1 m (with window, window width 2 mm) at a pressure (nitrogen) of 0.5 kg / cm ^2. After removing the liquid, both ends of the capillary tube were sealed and heated at 110 ° C. for 6 hours. Thereafter, 2 ml of dichloromethane, 1 ml of methanol and acetone were passed through for washing and drying. Next, 200 mM-potassium dihydrogen phosphate aqueous solution and 200 mM-potassium dihydrogen phosphate aqueous solution are prepared and mixed to prepare a 200 mM-phosphate buffer (pH = 4), and 0.5 ml of the phosphate buffer is added. The solution was passed through a dried capillary tube, and then washed and dried by passing 1 ml of pure water and 1 ml of acetone.

Made of fused silica glass, 0.05 mm I.D. D. A solution prepared by mixing 50% toluene solution of (4-chlorosulfonylphenyl) ethyltrichlorosilane and [3- (dimethylamino) propyl] trimethoxysilane at a ratio of 4 to 1 (V / V) in a 1 m capillary tube was 0 The solution was passed through at a pressure of 0.5 kg / cm ² (nitrogen). After removal of the solution, both ends of the capillary tube were sealed and heated at 110 ° C. for 6 hours. Thereafter, as in Example 1, it was produced by post-treatment, that is, washing and drying.

Made of fused silica glass, 0.05 mm I.D. D. Pass [3- (dimethylamino) propyl] trimethoxysilane through a 1 m capillary tube at a pressure (nitrogen) of 0.5 kg / cm ² , and after removing the liquid, seal both ends of the capillary tube at 220 ° C. For 10 hours. Thereafter, it was manufactured by washing and drying in the same manner as in Example 1.

  Various experiments conducted using the inner wall chemically modified capillary tube of the present invention, the inner wall untreated capillary tube, and the inner wall coated capillary tube in which the inner wall of the capillary is coated with an ionic polymer will be described below. In addition, all are 0.05mmI. D. A capillary tube of × 645 mm was used, and the inner wall chemically modified capillary tube of the present invention was a capillary tube manufactured by the same production method as in Example 1 above (hereinafter sometimes referred to as the capillary tube obtained in Example 1 above). The inner wall untreated capillary tube was a fused silica tube manufactured by polymicro technology, and the inner wall coated capillary tube whose inner wall was coated with an ionic polymer was a SMILE (−) column manufactured by Nacalai Tesque. The capillary electrophoresis apparatus used was an Agilent 3D capillary electrophoresis system.

  In the table below and FIGS. 1 and 2, “Chemical Modified” is the capillary tube obtained in Example 1, and “Coated” is a capillary tube coated with the above-mentioned commercially available ionic polymer as a control, “Untreat” means the above-described untreated capillary tube. CV (%) indicates a coefficient of variation value, and when this value is low, it means that reproducibility is high.

Experimental Example 1 Table 1 shows the results of Experimental Example 1 of CZE under conditions of capillary zone electrophoresis pH = 6. In the inner wall untreated capillary tube, the dissociation of silanol groups is unstable and EOF is considered to be slow. The analysis samples include DL-pantothenic acid (hereinafter sometimes referred to as PA), o-nitrobenzoic acid (hereinafter sometimes referred to as NBA) and p-toluenesulfonic acid (hereinafter referred to as TSA) having a negative charge at pH = 6. ), Neutral O-ethoxybenzamide (hereinafter sometimes referred to as EBA), positively charged phenylethylamine (hereinafter sometimes referred to as PEA), and N-1-naphtylenediamine (hereinafter sometimes referred to as NDA). It was. In CZE using an inner wall untreated capillary tube, PA, NBA, and TSA were not detected even after a migration time of 40 minutes. In addition, when a capillary tube coated with an ionic polymer is used, it takes about 40 minutes to detect NBA and TSA. On the other hand, in the capillary tube obtained in Example 1, since a fast EOF was obtained, all the peaks of PEA, NDA, EBA, PA, NBA and TSA were detected within a migration time of 13 minutes. As is clear from the above, when the capillary tube obtained in Example 1 was used, simultaneous analysis of positive charge, negative charge and neutral compound became possible, and the analysis time was shortened.

  The reason why the electroosmotic flow becomes faster by using the capillary tube of the present invention is as follows. That is, EOF becomes faster as the zeta potential increases. Silanol groups exist on the inner wall surface of the untreated capillary tube, and dissociation of the silanol groups occurs at pH = 4 or higher. The counter ion with respect to the silanol group is attracted near the inner wall in order to balance the electric charge to form an electric double phase, and a zeta potential is generated. The zeta potential is determined by the surface charge on the inner wall of the capillary tube, but is small because the dissociation of the silanol group is unstable. However, chemical modification with a compound having a polar group increases the surface charge, thereby increasing the zeta potential and increasing the EOF.

Table 1 is a table showing the migration time of the solute in each capillary tube. The unit of numerical values in the table is minutes (min).

Experimental Example 2 Reproducibility of travel time in CZE Migration time is an important factor, and the reproducibility leads to the original reliability of analysis. Tables 2 to 4 show experimental examples when measured seven times by capillary zone electrophoresis under the condition of pH = 8. The sample similar to Experimental example 1 was used for the analysis sample. Since the dissociation of silanol groups was unstable in the inner wall untreated capillary tube, the reproducibility was low. In addition, when a capillary tube coated with an ionic polymer was used, the reproducibility was higher than that of the inner wall untreated capillary tube, but the migration time was longer than that of the inner wall untreated capillary tube. On the other hand, the capillary tube obtained in Example 1 had a CV (%) value lower than that of a commercially available capillary tube coated with an ionic polymer, and showed high reproducibility. And the migration time is short. As is clear from the above, it was possible to obtain high reproducibility by using the capillary tube according to the present invention.

Table 2 shows the solute migration time and reproducibility in the inner wall chemically modified capillary tube of the present invention.

Table 3 shows the migration time and reproducibility of the solute in the inner wall untreated capillary tube.

Table 4 shows the migration time and reproducibility of the solute in the inner wall coated capillary tube.

  From the results of Experiment 2 above, the capillary tube according to the present invention was recognized to have higher reproducibility in migration time than the untreated capillary tube and a commercially available capillary tube coated with an ionic polymer.

  The reason why the stability and reproducibility are good by using the capillary tube of the present invention is as follows. That is, although the dissociation of silanol groups is unstable, the polar group bonded to the inner wall surface of the capillary tube according to the present invention is in an ionized state in a wide pH range, so that stable EOF is obtained and high reproducibility is recognized. is there.

  Table 5 shows a comparison of the reproducibility. In the table, TSA Mt means the average migration time of p-toluenesulfonic acid when measured 7 times. Therefore, the essential difference between the inner wall untreated capillary tube and the ionic polymer coated capillary tube and the capillary tube according to the present invention is that in this example, the capillary tube according to the present invention has a fast EOF and high reproducibility. For this reason, a remarkable effect as shown in the experimental example is brought about.

  This is because in the present invention, the remaining silanol can be completely crushed by reacting a compound having both a reactive group reactive to a silanol group and a polar group that accelerates EOF directly with silanol. Further, as an advantage of this method of the present invention, since a single phase polar group can be introduced, there is no difference in thickness unlike a polymer coating. Therefore, it is possible to solve the problem that it is difficult to obtain the reproducibility which has been a problem in the past.

Table 5 is a table showing a comparison of reproducibility of each capillary tube by CZE (pH = 8).

Experimental Example 3 Micellar Electrokinetic Chromatography under Neutral Conditions Micellar Electrokinetic Chromatography (hereinafter sometimes referred to as MEKC) is an electrophoretic separation mode that uses a pseudo stationary phase. Similar to substances, neutral substances can be separated by adding a charged surfactant to the electrophoresis solution. Surfactant micelles move in the same direction as the electroosmotic flow or in the opposite direction, depending on the type of charge. Neutral substances are separated according to the difference in the amount taken into the micelle, and the movement time becomes longer as the interaction with the micelle increases. Therefore, simultaneous analysis is impossible with the prior art, or a very long analysis time is required even for a sample that can be analyzed. FIG. 1 shows an experimental example of MEKC using the capillary tube obtained in Example 1 under the condition of pH = 6. Caffeine, catechin (hereinafter sometimes referred to as “C”), epigallocatechin (hereinafter sometimes referred to as “EGC”), epigallocatechin gallate (hereinafter sometimes referred to as “EGCG”), epicatechin (hereinafter sometimes referred to as “EC”), Analysis was performed using epicatechin gallate (hereinafter sometimes referred to as ECG) and catechin gallate (hereinafter sometimes referred to as CG). The inner wall untreated capillary tube and the capillary tube coated with ionic polymer took about 30 minutes to detect all solutes. When a capillary tube coated with an ionic polymer was used, epigallocatechin gallate and epicatechin gallate could not be detected. On the other hand, simultaneous analysis was achieved within 10 minutes in the capillary tube obtained in Example 1. That is, by using the capillary tube according to the present invention, simultaneous analysis of neutral compounds can be performed in MEKC in a short time.

Experimental Example 4 Reproducibility of migration time in MEKC The time required for the solute in micellar electrokinetic chromatography to move to the detector is called migration time and is an important factor as well as the migration time of capillary zone electrophoresis. Tables 6 to 8 show experimental examples when measured seven times by micellar electrokinetic chromatography under the condition of pH = 6. The sample similar to Experimental example 3 was used for the analysis sample. Since the dissociation of silanol groups is unstable in the inner wall untreated capillary tube, the reproducibility is low even in MEKC. On the other hand, the capillary tube obtained in Example 1 had a CV value of 0.25% or less, indicating very high reproducibility. As apparent from the above, when the capillary tube according to the present invention is used, high reproducibility can be obtained even in MEKC.

Table 6 shows the migration time and reproducibility of the solute in the inner wall chemically modified capillary tube.

Table 7 is a table showing the migration time and reproducibility of the solute in the inner wall untreated capillary tube.

Table 8 is a table showing the migration time and reproducibility of the solute in the inner wall coated capillary tube.

Experimental Example 5 Change in EBA Migration Time with Change in pH of Electrophoresis in Capillary Zone Electrophoresis The pH of the electrophoresis solution was changed in CZE, and the migration time of EBA was measured at each pH. The results are shown in FIG. The conventionally used inner wall untreated capillary tube (Untreat) has silanol groups on the inner wall, so that the electroosmotic flow depends on the dissociation of the silanol groups. The lower the pH of the electrophoresis solution, the more the silanol group dissociation was suppressed, the EOF was delayed, and the migration time was prolonged. The capillary tube (Chemical Modified) chemically modified with the sulfone group obtained in Example 1 has an EOF independent of the pH of the electrophoresis solution, and the EOF is fast. On the other hand, a commercially available capillary tube coated with an ionic polymer (Coated) had a faster EOF than an untreated capillary tube under acidic conditions, but slowed under neutral or higher conditions. From the above, a fast EOF was obtained by the capillary tube according to the present invention, and the analysis time could be extremely shortened.

FIG. 1 is a diagram showing micellar electrokinetic chromatography at pH = 6. Chemical Modified means a capillary tube according to the present invention, Untreat and Coated are control capillary tubes, Untreat means an untreated capillary tube, and Coated means a commercially available capillary tube coated with an ionic polymer . FIG. 2 is a graph plotting the migration time of EBA at each pH when the pH of the electrophoresis solution is changed in capillary zone electrophoresis. Chemical Modified means a capillary tube according to the present invention, Untreat and Coated are control capillary tubes, Untreat means an untreated capillary tube, and Coated means a commercially available capillary tube coated with an ionic polymer .

Claims (9)

A capillary tube characterized in that a compound having a polar group for adding a surface charge and a reactive group is chemically bonded to a silanol group on the inner wall surface of a fused silica glass capillary tube to form a stable dissociative inner wall surface . 2. The capillary tube according to claim 1, wherein the capillary tube is a capillary tube used for electrophoresis or a capillary tube for electrochromatography. 2. The capillary tube according to claim 1, wherein the capillary tube is a connection pipe having a liquid as a mobile phase. 4. The compound having a polar group is an organic monomer having a polar group that increases the surface charge on the inner wall surface of the capillary tube and an inorganic metal bonded to the reactive group. A capillary tube according to any one of the above. The capillary tube according to claim 4, wherein the inorganic metal is selected from the group consisting of silicon, titanium and zirconium. The polar group of the organic monomer is a sulfone group, a carboxyl group, a cyano group, a quaternary ammonium group, a primary to tertiary amino group, or a trifluoro group that is chemically bonded to the inner wall surface and has a high surface charge. The capillary tube according to any one of claims 1 to 5, which is at least one kind of group. A capillary tube characterized in that a compound having a polar group for adding a surface charge and a reactive group is chemically bonded to a silanol group on the inner wall surface of a fused silica glass capillary tube to form a stable dissociative inner wall surface . Production method. It is characterized by washing with an organic solvent or / and an acidic solution or / and an alkaline solution or / and a surfactant after chemical bonding to remove reaction by-products or re-dissociate polar groups. The method for producing a capillary tube according to claim 7. 9. The method for producing a capillary tube according to claim 7, wherein the capillary tube is washed and dried after being chemically bonded.

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