JP7534254B2 - Chromatography tube and its manufacturing method, and high performance liquid chromatograph - Google Patents

Description

The present disclosure relates to a chromatography tube, a method for manufacturing the same, and a high performance liquid chromatograph.

A high-performance liquid chromatograph is a device that fills stainless steel or glass chromatography tubes with a packing material, supplies an appropriate mobile phase (eluent) to transport a sample containing a variety of components, and separates the components in the sample through the interaction between the packing material and the components. Such high-performance liquid chromatographs are widely used in fields such as biochemistry, medicine, and pharmacology because they can separate and analyze samples simultaneously under mild conditions.

However, when analyzing biologically active components such as proteins and enzymes using stainless steel chromatography tubes, the biologically active components may be adsorbed onto the stainless steel, resulting in a significant drop in recovery rate. When using glass chromatography tubes, there is the problem of adsorption to silanol groups present on the glass surface. Furthermore, glass chromatography tubes have a narrow usable pH range and cannot be used in strong alkali conditions.

For this reason, in recent years, chromatography tubes made of resin have been developed that are superior to stainless steel or glass chromatography tubes in terms of chemical resistance, corrosion resistance, adsorption resistance, etc. Patent Document 1 proposes a chromatography tube having a resin pipe and a resin jacket tube that is in close contact with the outer surface of the resin pipe.

JP 2007-64725 A

The objective of the present disclosure is to provide a chromatography tube in which shedding originating from the inner circumferential surface is suppressed even when the mobile phase passes through the through-holes, and a method for manufacturing the same.

The chromatography tube according to the present disclosure includes a ceramic cylindrical body having an axial through hole and composed primarily of zirconium oxide or zirconium aluminum composite oxide.

The method for manufacturing the chromatography tube according to the present disclosure includes the steps of: placing a powder, wax, a dispersant, and a plasticizer, the main components of which are at least one of zirconium oxide and aluminum oxide, the cumulative 95% by volume of which has a particle size of 6.5 μm or less in a cumulative distribution curve, in a container and stirring the powder; preheating the slurry; degassing the preheated slurry; forming the slurry to obtain a cylindrical body; and firing the body.

The high performance liquid chromatograph of the present disclosure is equipped with the above-mentioned chromatography tube.

The chromatography tube according to the present disclosure has excellent chemical resistance and mechanical strength, and even when the mobile phase passes through the through holes of the cylindrical body, there is little risk of shedding starting from the inner peripheral surface. Therefore, according to the present disclosure, contamination of the mobile phase due to shedding is suppressed, and highly accurate analysis can be performed over a long period of time.

FIG. 1 is a schematic diagram showing an example of an outline of a high performance liquid chromatograph equipped with a chromatography tube according to the present disclosure. FIG. 2A is a partially cutaway perspective view of a chromatography tube according to one embodiment of the present disclosure, and FIG. 2B is an enlarged view of part B thereof. 1A is a micrograph (magnification: 20 times) showing the observation surface of the chromatography tube of sample No. 1 of the embodiment, and FIG. 1B is a micrograph (magnification: 200 times) showing an enlarged view of part D of the same. 1A is a micrograph (magnification: 20 times) showing the observation surface of the chromatography tube of sample No. 4 (comparative example) of the embodiment, and FIG. 1B is a micrograph (magnification: 200 times) showing an enlarged view of part E of the same.

The chromatography tube and its manufacturing method, as well as the high-performance liquid chromatograph of the present disclosure, will be described below with reference to the drawings. Figure 1 is a schematic diagram showing an example of an outline of a high-performance liquid chromatograph using the chromatography tube of the present disclosure.

The high-performance liquid chromatograph 10 shown in FIG. 1 is an apparatus equipped with solenoid valves 2a and 2b, a pump 3, a sample introduction device 4, a column 5, a detector 6, a data processing device 7, and a filter 8. Each of the devices constituting the high-performance liquid chromatograph 10, such as the solenoid valves 2a and 2b and the pump 3, is controlled by a control unit (not shown).

In FIG. 1, an example of gradient elution is shown with multiple eluents, mobile phases 1a and 1b. Gradient elution refers to a method of elution in which the composition ratio of the eluent is changed continuously or stepwise over the elution time. Solenoid valves 2a and 2b are provided corresponding to mobile phases 1a and 1b, respectively, and selectively switch the supply of mobile phases 1a and 1b. Pump 3 supplies mobile phases 1a and 1b selected by switching each solenoid valve 2a and 2b to sample introduction device 4 at a constant pressure. Sample introduction device 4 introduces the sample supplied by pump 3, together with mobile phases 1a and 1b, into column 5 via filter 8, which removes foreign matter.

Column 5 is composed of chromatography tube 5a and packing material 5b packed in chromatography tube 5a. The inner peripheral surface of chromatography tube 5a is the surface that comes into contact with mobile phases 1a, 1b and packing material 5b. Chromatography tube 5a has, for example, an outer diameter of 2 mm to 20 mm, an inner diameter of 0.5 mm to 15 mm, and a length of 50 mm to 250 mm.

The packing material 5b is a granular stationary phase, particles holding the stationary phase, and a monolithic stationary phase. The components to be analyzed contained in the sample are separated into individual components in the column 5 by supplying the mobile phases 1a and 1b to the column 5, and are sequentially discharged from the column 5 toward the detector 6. The detector 6 detects the components discharged from the column 5. The data processing device 7 analyzes the sample qualitatively or quantitatively based on the detection results of the components by the detector 6.

As shown in FIG. 2(A), the chromatography tube 5a used in the high-performance liquid chromatograph 10 is made of a ceramic cylindrical body having a through hole 5h in the axial direction and mainly composed of zirconium oxide or zirconium aluminum composite oxide. With this configuration, a chromatography tube 5a with excellent chemical resistance and mechanical strength is obtained. As a result, even if the mobile phases 1a and 1b pass through the through hole 5h, there is little risk of particle shedding. Therefore, contamination of the mobile phases 1a and 1b due to this particle shedding is suppressed, making it possible to perform highly accurate analysis over a long period of time.

In the present disclosure, the term "main component" refers to a component that occupies 80 mass% or more of the total 100 mass% of the components constituting the ceramic. For example, when _the main component is a zirconium aluminum composite oxide, the content of zirconium converted to oxide ( _ZrO2 ) and the content of aluminum converted to oxide ( _Al2O3 ) are 80 mass% or more in total. Examples of the zirconium aluminum composite oxide include zirconia-reinforced alumina (ZTA) and alumina-reinforced zirconia (ATZ).

The presence of zirconium oxide or zirconium aluminum composite oxide can be identified and confirmed using an X-ray diffraction apparatus using CuKα radiation. The content of each component can be determined, for example, using an ICP (Inductively Coupled Plasma) emission spectrometer or an X-ray fluorescence analyzer.

2(A) and its partially enlarged view, FIG. 2(B), show the state of the chromatography tube 5a of the present disclosure polished from the outer surface toward the axis C. According to the present disclosure, when the obtained polished surface is the observation surface 5d, the number of recesses 5f having a depth d of 10 μm to 20 μm, starting from the ridge line 5e between the inner surface 5c of the chromatography tube 5a and the observation surface 5d, is 2 or less, preferably 1 or less per 1 mm of the length of the ridge line 5e. The recesses 5f are, for example, recessed. The reason for polishing from the outer surface of the chromatography tube 5a toward the axis C is to make it easier to measure the depth d of the recesses 5f. The direction of the depth d is the direction from the ridge line 5e toward the outer edge 5j, which is the boundary between the outer surface and the observation surface 5d, within the observation surface 5d.

The arithmetic mean roughness (Ra) of the observation surface 5d is, for example, 0.01 μm or more and 0.1 μm or less, and the arithmetic mean roughness (Ra) may be determined in accordance with JIS B 0601:2013. To obtain the observation surface 5d, a polishing material made of WA (white alundum) with an average particle size (D50) of 1 μm and a polisher made of pitch may be used as the polishing disk. In the case of a chromatography tube with a wall thickness of 3 mm or more, the chromatography tube 5a may be ground from the outer circumferential surface toward the axis C, leaving a polishing allowance of 0.1 mm to 0.2 mm, and then polished.

For an image (e.g., 2.3 mm horizontal, 1.7 mm vertical) of the observation surface 5d taken with a scanning electron microscope, the depth d of the recesses 5f can be measured using free software such as "Pinch Ruler" and the number of recesses 5f with a depth d of 10 μm to 20 μm can be counted. The depth of the recesses 5f is set to 10 μm or more because 10 μm is the minimum value, i.e., the threshold value, at which shed and suspended particles have a significant adverse effect on the mobile phases 1a and 1b.

In this way, since there are almost no recesses 5f on the inner peripheral surface 5c of the cylindrical body, the occurrence of shedding originating from the inner peripheral surface 5c is suppressed. Therefore, even if the mobile phases 1a and 1b pass through the through holes 5h, there is little risk of shedding originating from the inner peripheral surface 5c, so contamination of the mobile phases 1a and 1b due to shedding is further suppressed. The recesses 5f refer to depressions that open into the inner peripheral surface 5c of the cylindrical body.

In the observation surface 5d, the straightness of the ridgeline 5e is preferably 20 μm or less. Straightness refers to the deviation of the ridgeline 5e from a geometrically correct straight line, and the straightness of the ridgeline 5e can be measured, for example, using free software called "Pinch Ruler" on an image (e.g., 1.2 mm horizontally and 1.4 mm vertically) of the observation surface 5d taken with an optical microscope. The axial direction of the chromatography tube 5a is aligned with the vertical direction of the image, and at least one of the left and right ridgelines 5e sandwiching the inner surface 5c is included in the image, and the length of the geometrically correct straight line is set to 1.4 mm.

In the present disclosure, if the straightness of the ridge 5e is 20 μm or less, there is no large recess 5f on the inner circumferential surface 5c. Therefore, even if the flow of the mobile phases 1a and 1b is turbulent, there is little risk of particles shedding starting from the inner circumferential surface 5c. As a result, contamination of the mobile phases 1a and 1b due to this shedding is suppressed.

Furthermore, in the observation surface 5d, the maximum diameter m of the closed pores 5g within a range of 0.1 mm from the ridge 5e toward the outer edge 5j, which is the boundary between the outer circumferential surface of the chromatography tube 5a and the observation surface 5d, is preferably 0.9 μm or less. In other words, since there are no large closed pores 5g near the inner circumferential surface 5c, cracks are unlikely to occur from the closed pores 5g toward the inner circumferential surface 5c even when heating and cooling are repeated. As a result, shedding caused by these cracks is also unlikely to occur, and contamination of the mobile phases 1a and 1b due to shedding is suppressed.

The maximum diameter m of the closed pores 5g can be measured, for example, by using free software called "Pinch Ruler" to measure an image (e.g., 1.2 mm horizontally and 1.4 mm vertically) of the observation surface 5d taken with an optical microscope. The axial direction of the chromatography tube 5a is aligned with the vertical direction of the image, and at least one of the left and right ridges 5e that sandwich the inner surface 5c is included in the image.

The inner peripheral surface 5c of the cylindrical body may be a sintered surface with a root-mean-square slope (RΔqi) of 1.3 or less. With this configuration, the inner peripheral surface 5c is free of a crushed layer and has a controlled root-mean-square slope (RΔqi). As a result, even if the mobile phases 1a and 1b pass through the through holes 5h, they are less likely to fall out, and contamination of the mobile phases 1a and 1b is suppressed.

The inner peripheral surface 5c of the cylindrical body may be a fired surface with a cutting level difference (Rδci) of 1.7 μm or less, which represents the difference between the cutting level at a load length ratio of 25% on the roughness curve and the cutting level at a load length ratio of 75% on the roughness curve. With this configuration, the inner peripheral surface 5c has no crushed layer and the cutting level difference (Rδci) is in a controlled state. As a result, even if the mobile phases 1a and 1b pass through the through holes 5h, particle shedding is unlikely to occur, and contamination of the mobile phases 1a and 1b is further suppressed. In particular, it is preferable that the cutting level difference (Rδci) of the inner peripheral surface 5c is a fired surface of 1.4 μm or less.

The outer peripheral surface of the cylindrical body may be a fired surface with a cut level difference (Rδco) of 0.04 μm or more, which represents the difference between the cut level at a load length ratio of 25% on the roughness curve and the cut level at a load length ratio of 75% on the roughness curve. With this configuration, the outer peripheral surface does not have a crushed layer, so even if the cylindrical body is repeatedly attached, removed, and cleaned, particles are unlikely to fall off from the outer peripheral surface. Furthermore, hydrophilicity is improved, so dirt is less likely to adhere. In particular, it is preferable for the outer peripheral surface to have a cut level difference (Rδco) of 0.26 μm or more.

The root mean square slope (RΔqi, RΔqo) and the cut level difference (Rδci, Rδco) can be measured in accordance with JIS B 0601:2001 using a shape analysis laser microscope (Keyence Corporation, VK-X1100 or its successor). The measurement conditions are as follows: first, the illumination method is a coaxial epi-illumination method, the magnification is 480x, there is no cutoff value λs, the cutoff value λc is 0.08mm, there is no cutoff value λf, there is end effect correction, and the measurement range per point from the inner peripheral surface 5c and the outer peripheral surface to be measured is set to, for example, 710μm×533μm. For each measurement range, four lines to be measured are drawn at approximately equal intervals along the longitudinal direction of the measurement range, and line roughness measurement is performed. The measurement range is two points in total, one in the center of the axial direction, and the length to be measured is, for example, 560 μm.

Next, a method for manufacturing a chromatography tube according to the present disclosure will be described. First, a case in which the main component of the ceramic is zirconium oxide will be described. A powder containing zirconium oxide as the main component (hereinafter, may be referred to as zirconium oxide powder), a powder containing yttrium oxide as the main component (hereinafter, may be referred to as yttrium oxide powder), wax, a dispersant, and a plasticizer are prepared. The yttrium oxide powder is a stabilizer.

The zirconium oxide powder should have a purity of 99.9% by mass or more, and a cumulative 95% by volume particle size in the cumulative distribution curve of 6.5 μm or less, preferably 6 μm or less. If the cumulative 95% by volume particle size is in this range, the number of pores in the obtained cylindrical body is small, and the occurrence of recesses 5f on the inner surface 5c is suppressed.

The cumulative distribution curve refers to a curve showing the cumulative distribution of particle sizes in a two-dimensional graph with particle size on the horizontal axis and cumulative percentage of particle size on the vertical axis. The cumulative distribution curve can be determined by the laser diffraction scattering method using, for example, a particle size distribution measuring device manufactured by Microtrac-Bell (MT3300 or its successor model).

For a total of 100 parts by mass of the zirconium oxide powder and yttrium oxide powder, the wax is 13 parts by mass to 14 parts by mass, the dispersant is 0.4 parts by mass to 0.5 parts by mass, and the plasticizer is 1.4 parts by mass to 1.5 parts by mass. The yttrium oxide powder in a total of 100 mol % of the zirconium oxide powder and yttrium oxide powder is, for example, 2 mol % to 4 mol %. The zirconium oxide powder, yttrium oxide powder, wax, dispersant, and plasticizer are contained in a resin container heated to 90°C to 140°C. At this time, the wax, dispersant, and plasticizer are in liquid form.

Next, the container is placed in a stirrer and rotated for three minutes (rotational kneading process) to stir the zirconium oxide powder, yttrium oxide powder, wax, dispersant, and plasticizer to obtain a slurry. Next, the resulting slurry is filled into a syringe, and a degassing tool is used to degas the slurry while rotating the syringe for one minute. Before the degassing process, it is recommended to preheat the slurry to a temperature of 120°C or higher and 180°C or lower.

Next, the syringe filled with the degassed slurry is attached to an injection molding machine, and the slurry is molded while maintaining the temperature at 90°C or higher to obtain a cylindrical molded body. When molding, a cylindrical core that forms the inner circumferential surface of the cylindrical molded body is attached to the injection molding machine in advance. It is also advisable to maintain the flow path of the injection molding machine through which the slurry passes at 90°C or higher.

The obtained molded bodies are degreased and fired in sequence to obtain a cylindrical body made of ceramics whose main component is zirconium oxide. The firing atmosphere is air, the firing temperature is 1400°C to 1800°C, and the holding time is 2 hours to 4 hours. To obtain a cylindrical body in which the maximum diameter of closed pores is 0.9 μm or less within a range of 0.1 mm from the ridge line to the outer edge, which is the boundary between the outer peripheral surface of the cylindrical body and the observation surface, on the observation surface, the firing temperature is 1500°C to 1800°C, and the holding time is 3 hours to 4 hours.

The cylindrical body obtained by the above manufacturing method has 2 or less recesses 5f per 1 mm of the length of the ridge 5e, the depth of which is 10 μm or more and 20 μm or less from the ridge 5e. By making the straightness of the outer peripheral surface of the core used in molding 15 μm or less, the straightness of the ridge 5e can be made 20 μm or less. Therefore, when the above-mentioned chromatography tube 5a is used as the cylindrical body of the column 5, the occurrence of shedding starting from the inner peripheral surface 5c can be suppressed.

When the main component of the ceramic is zirconium aluminum composite oxide, a chromatography tube can be obtained as follows.

A powder mainly composed of aluminum oxide with a purity of 99.9% by mass or more and an average particle size of 0.3 to 0.7 μm (hereinafter sometimes referred to as aluminum oxide powder), zirconium oxide powder with a purity of 99.9% by mass or more and an average particle size of 0.1 to 0.3 μm, yttrium oxide powder, silicon oxide, titanium oxide, and magnesium hydroxide powders, each with a purity of 99.5% by mass or more and an average particle size of 0.5 to 1.0 μm, wax, a dispersant, and a plasticizer are prepared. The yttrium oxide powder is a stabilizer. The silicon oxide, titanium oxide, and magnesium hydroxide powders are sintering aids that promote sintering.

For example, the content of aluminum oxide powder in the total of 100 mass% of the above powders is 65 mass% or more and 96 mass% or less. The content of zirconium oxide powder in the total of 100 mass% of the above powders is 4 mass% or more and 34.4 mass% or less. The content of yttrium oxide powder in the total of 100 mol% of zirconium oxide powder and yttrium oxide powder is, for example, 3 mol% or less.

For example, the content of silicon oxide powder is 0.2% by mass or more and 1.8% by mass or less, the content of titanium oxide powder is 0.22% by mass or more and 2% by mass or less, and the content of magnesium hydroxide powder is 0.17% by mass or more and 1.2% by mass or less, and the total content of these sintering aids is adjusted to 0.6% by mass or more and 4.5% by mass or less. If the sintering aids are in this range, the eutectic temperature will be 1300°C or less, sintering will be greatly promoted, and highly dense ceramics can be obtained.

The aluminum oxide powder and zirconium oxide powder should both have a cumulative 95% by volume particle size in the cumulative distribution curve of 6.5 μm or less, preferably 6 μm or less. If the cumulative 95% by volume particle size is within this range, the number of pores in the obtained cylindrical body is small, and the occurrence of recesses 5f on the inner surface 5c is suppressed.

The powders, wax, dispersant and plasticizer can be placed in a resin container, stirred, degassed, molded and degreased in the same manner as described above.

For firing, the firing atmosphere should be air, the firing temperature should be 1300°C or higher and 1450°C or lower, and the holding time should be 1 hour or higher and 4 hours or lower. To obtain an aluminum oxide sintered body in which the maximum diameter of closed pores within a range of 0.1 mm from the ridge line to the outer edge, which is the boundary between the outer peripheral surface of the cylindrical body and the observation surface, is 0.9 μm or lower, the firing temperature should be 1350°C or higher and 1450°C or lower, and the holding time should be 2 hours or higher and 4 hours or lower.

The cylindrical body obtained by the above manufacturing method has 2 or less recesses 5f with a depth of 10 μm to 20 μm from the ridge 5e per 1 mm of the length of the ridge 5e. By making the straightness of the outer circumferential surface of the core used in molding 15 μm or less, the straightness of the ridge 5e can be made 20 μm or less. Therefore, when the above-mentioned chromatography tube 5a is used as the cylindrical body of the column 5, the occurrence of shedding starting from the inner circumferential surface 5c can be suppressed.

This disclosure is not limited to the above-described embodiments, and various modifications, improvements, combinations, etc. are possible without departing from the spirit and scope of this disclosure.

The following describes specific examples, but the present embodiment is not limited to these examples.

Example 1
As the raw powder, zirconium oxide powder and yttrium oxide powder with a purity of 99.99% by mass were used, and the raw powder with the cumulative 95% by volume particle size in the cumulative distribution curve shown in Table 1 was used. The yttrium oxide powder in 100 mol% of this raw powder was 3 mol%. This raw powder, wax, dispersant and plasticizer were heated to 90°C, then placed in a resin container and mixed. Next, the container was placed at a predetermined position of the stirrer, and the container was rotated for 3 minutes (rotational kneading process) to obtain a slurry. The wax was 13.5 parts by mass, the dispersant was 0.45 parts by mass, and the plasticizer was 1.45 parts by mass relative to 100 parts by mass of the raw powder.

The obtained slurry was filled into a syringe, and the syringe was rotated and revolved for 1 minute using a defoaming tool to defoam the slurry. Next, the syringe was attached to an injection molding machine, and the slurry was molded while maintaining the temperature of the slurry at 90°C or higher to obtain a cylindrical molded body. When molding, a cylindrical core that forms the inner surface of the cylindrical molded body was attached to the injection molding machine in advance. The straightness of the outer surface of the core was 20 μm or more and 25 μm or less. At this time, the slurry flow path of the injection molding machine was also maintained at 90°C or higher.

The resulting molded bodies were degreased and fired in sequence to obtain cylindrical chromatography tubes (samples No. 1 to 4). The firing atmosphere was air, the firing temperature was 1450°C, and the holding time was 3 hours.

Each sample was examined using an X-ray diffraction apparatus with CuKα radiation, and the presence of zirconium oxide and yttrium oxide was confirmed. The content of each metal element was measured using an ICP (Inductively Coupled Plasma) emission spectrometer, and it was found that zirconium had the highest content in all samples.

For each sample shown in Table 1, the cumulative 95% by volume particle size in the cumulative distribution curve of the raw powder, the number of recesses 5f originating from the ridge 5e with the observation target surface 5d, and the number of particles generated when pure water was supplied to and discharged from the through hole 5h of each sample were measured using the following methods. The results of these measurements are shown in Table 1.

(1) Particle diameter at cumulative 95% by volume in cumulative distribution curve The particle diameter at cumulative 95% by volume in the cumulative distribution curve was measured using a particle size distribution measuring device (MT3300) manufactured by Microtrac Bell.

(2) Number of recesses starting from the ridgeline with the observation surface First, the outer peripheral surface of the chromatography tube 5a was polished toward the axis C to obtain an observation surface 5d having an arithmetic mean roughness Ra of 0.01 μm or more and 0.1 μm or less. The depth d of the recesses 5f was measured using a free software "Clasp Ruler" for an image (2.3 mm in the horizontal direction, 1.7 mm in the vertical direction) of the observation surface 5d taken with a scanning electron microscope. The number of recesses 5f having a depth d of 10 μm or more and 20 μm or less was counted.

(3) Number of particles generated when pure water is supplied to and discharged from the through hole of each sample A container was connected to the opening on the discharge side of the through hole 5h of each sample. Next, pure water was supplied from the opening on the supply side of the through hole 5h at a flow rate of 5 mL/sec for 100 seconds, and the number of particles contained in the pure water discharged into the container was measured using a liquid particle counter (LPC). The particles to be measured were those with a diameter exceeding 0.2 μm. In addition, the container was ultrasonically cleaned before connection, and it was confirmed that the number of particles with a diameter exceeding 0.2 μm was 20 or less.

As shown in Table 1, samples No. 1 to 3 had 2 or less recesses per mm with a depth of 10 μm to 20 μm. Therefore, samples No. 1 to 3 generate fewer particles and are less likely to contaminate the mobile phase.

Example 2
A cylindrical molded body whose main component was zirconium oxide was obtained by the same method as that shown in Example 1. When molding, a cylindrical core forming the inner peripheral surface of the cylindrical molded body was attached to the injection molding machine in advance. Zirconium oxide powder having a cumulative 95 volume % particle size of 6 μm in a cumulative distribution curve measured using a particle size distribution measuring device (MT3300) manufactured by Microtrac Bell was molded. The straightness of the outer peripheral surface of the core was as shown in Table 2.

The resulting molded bodies were degreased and fired in sequence to obtain cylindrical chromatography tubes (samples No. 5 to 8). The firing atmosphere was air, the firing temperature was 1450°C, and the holding time was 3 hours.

The straightness of the ridgeline 5e was measured using the free software "Pinch Ruler" for an image (1.2 mm horizontal, 1.4 mm vertical) of the observation surface 5d taken with an optical microscope. The axial direction of the chromatography tube was aligned with the vertical direction of the image, and the left and right ridgelines 5e sandwiching the inner peripheral surface 5c were included in the image. The length of a geometrically correct straight line is 1.4 mm. The straightness value of the left and right ridgelines 5e with the largest straightness is shown in Table 2. The number of particles generated when pure water was supplied to and discharged from the through-hole 5h of each sample was measured using the same method as shown in Example 1. The results are shown in Table 2.

As shown in Table 2, Nos. 5 to 7 have straightness of the ridges of 20 μm or less. Therefore, the number of particles generated is small, and it can be said that there is a lower risk of contaminating the mobile phase than No. 8.

Example 3
A cylindrical molded body whose main component was zirconium oxide was obtained by the same method as that shown in Example 1. When molding, a columnar core forming the inner peripheral surface of the cylindrical molded body was attached to the injection molding machine in advance. Zirconium oxide powder having a cumulative 95 volume % particle size of 5.5 μm in a cumulative distribution curve measured using a particle size distribution measuring device (MT3300) manufactured by Microtrac Bell was molded. The straightness of the outer peripheral surface of the core was set to 20 μm or more and 25 μm or less in all cases.

The resulting molded bodies were degreased and fired in sequence to obtain cylindrical chromatography tubes (samples No. 17 to 20). The firing atmosphere was air, the firing temperature was as shown in Table 3, and the holding time was 3.5 hours.

The maximum diameter m of the closed pores 5g was measured using the free software "Pinch Ruler" on an image (1.2 mm horizontal, 1.4 mm vertical) of the observation surface 5d taken with an optical microscope. The number of particles generated when pure water was supplied to and discharged from the through-holes 5h of each sample was measured using the same method as shown in Example 1. The results are shown in Table 3.

As shown in Table 3, in samples No. 9 to 11, the maximum diameter m of the closed pores 5g within a range of 0.1 mm from the ridge 5e toward the outer edge is 0.9 μm or less. Therefore, the number of particles generated is small, and it can be said that there is a lower risk of contaminating the mobile phase than in No. 12.

Reference Signs 1a, 1b Mobile phase 2a, 2b Solenoid valve 3 Pump 4 Sample introduction device 5 Column 5a Chromatography tube 5b Packing material 5c Inner surface 5d Observation target surface 5e Ridge line 5f Recess 5g Closed hole 5h Through hole 5j Outer edge 6 Detector 7 Data processing device 8 Filter 10 High performance liquid chromatograph

Claims (10)

The ceramic cylindrical body has a through hole in the axial direction and is mainly composed of zirconium oxide or zirconium aluminum composite oxide,
The number of recesses having a depth of 10 μm or more and 20 μm or less, starting from a ridge between the inner circumferential surface of the cylindrical body and the observation surface, which is a polished surface extending from the outer circumferential surface of the cylindrical body toward the axis, is 2 or less per 1 mm of the length of the ridge .
Chromatography tubes. The ceramic cylindrical body has a through hole in the axial direction and is mainly composed of zirconium oxide or zirconium aluminum composite oxide,
In the observation surface, which is a polished surface from the outer circumferential surface of the cylindrical body toward the axis , the straightness of the ridge between the inner circumferential surface of the cylindrical body and the observation surface is 20 μm or less .
Chromatography tubes. The ceramic cylindrical body has a through hole in the axial direction and is mainly composed of zirconium oxide or zirconium aluminum composite oxide,
In the observation surface, which is a polished surface from the outer circumferential surface of the cylindrical body toward the axis , the maximum diameter of closed pores within a range of 0.1 mm from the ridge between the inner circumferential surface of the cylindrical body and the observation surface toward the outer edge, which is the boundary between the outer circumferential surface of the cylindrical body and the observation surface, is 0.9 μm or less .
Chromatography tubes. 4. The chromatography tube according to claim 2, wherein the number of recesses having a depth of 10 μm or more and 20 μm or less and starting from the ridge line on the observation surface is 2 or less per 1 mm of the ridge line length. The chromatography tube according to any one of claims 1 to 4, wherein the inner peripheral surface of the cylindrical body is a fired surface having a root mean square slope (RΔqi) of 1.3 or less. The chromatography tube according to any one of claims 1 to 5, wherein the inner peripheral surface of the cylindrical body is a fired surface having a cut level difference (Rδci) of 1.7 μm or less, which represents the difference between the cut level at a load length ratio of 25% on the roughness curve and the cut level at a load length ratio of 75% on the roughness curve. The chromatography tube according to any one of claims 1 to 6, wherein the outer peripheral surface of the cylindrical body is a fired surface having a root mean square slope (RΔqo) of 0.04 or more. The chromatography tube according to any one of claims 1 to 7, wherein the outer peripheral surface of the cylindrical body is a fired surface with a cut level difference (Rδco), which represents the difference between the cut level at a load length ratio of 25% on the roughness curve and the cut level at a load length ratio of 75% on the roughness curve, of 0.04 μm or more. A method for producing a chromatography tube according to any one of claims 1 to 8, comprising the steps of:
A step of placing a powder containing at least one of zirconium oxide and aluminum oxide as a main component, the powder having a cumulative 95% by volume particle size of 6.5 μm or less in a cumulative distribution curve, a wax, a dispersant, and a plasticizer in a container and stirring the powder to obtain a slurry;
preheating the slurry;
A step of degassing the preheated slurry;
forming the slurry into a cylindrical compact;
and calcining the molded body. A high-performance liquid chromatograph equipped with a chromatography tube according to any one of claims 1 to 8.