Liquid chromatographic column, gas analysis method, and gas analysis system

Abstract

To provide a column for a liquid chromatograph capable of performing an analysis by easily and accurately separating a plurality of gases in a mixed gas.SOLUTION: A column for a liquid chromatograph used for separating and analyzing gases is filled with a filler inside thereof. The filler includes a first fine particle and a second fine particle, where the first particle is at least one of a hydrophilic fine particle, and a first hydrophobic fine particle having a plenty of pores, the second fine particle is a second hydrophobic fine particle having a plenty of pores fixed with a gas phase inside thereof, and an average pore diameter (A (nm)) of pores of the first hydrophobic fine particle and an average pore diameter (B (nm)) of pores of the second hydrophobic fine particle satisfy a relation of the following formula (1). A-B≥10 (1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid chromatographic column, a gas analysis method, and a gas analysis system. [Background technology]

[0002] Gas chromatography (GC) has traditionally been used as a method for separating and analyzing multiple gases contained in a gas mixture. Gas chromatography is a type of instrumental analysis method used to identify and quantify vaporizable compounds, and is widely used as a microanalysis technique in various scientific fields.

[0003] As an apparatus for analyzing gas components using gas chromatography, for example, an analytical apparatus equipped with a gas chromatograph column whose inner wall is coated with a stationary phase such as diphenyl or dimethyl silicone has been proposed (Patent Document 1). Also, a gas separation apparatus for separating a mixed gas containing rare gases and nitrogen gas has been proposed, which is equipped with a gas chromatograph column packed with a zeolite such as a molecular sieve (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-194456 [Patent Document 2] Japanese Patent Publication No. 2020-171894 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even when analytical devices using gas chromatograph columns as proposed in Patent Documents 1 and 2 are used, it is not necessarily easy to separate and analyze mixed gases containing various inorganic gases or ordinary air containing trace components with high accuracy. In particular, separating argon (Ar) and oxygen (O2) is difficult, and there has been a demand for technological development to more accurately and easily separate and analyze gases containing multiple gases that are difficult to separate.

[0006] The present invention has been made in consideration of the problems of the prior art, and an object of the present invention is to provide a liquid chromatograph column that can easily separate and analyze multiple gases in a gas mixture with high accuracy. Another object of the present invention is to provide a gas analysis method and a gas analysis system that use this liquid chromatograph column. [Means for solving the problem]

[0007] That is, according to the present invention, there is provided the following liquid chromatographic column. [1] A liquid chromatography column used for separating and analyzing gases, the column being filled with a packing material, the packing material comprising first and second microparticles, the first microparticles being at least one of hydrophilic microparticles and first hydrophobic microparticles having a large number of pores, the second microparticles being second hydrophobic microparticles having a large number of pores in which a gas phase is immobilized, and the average pore diameter (A (nm)) of the pores of the first hydrophobic microparticles and the average pore diameter (B (nm)) of the pores of the second hydrophobic microparticles satisfying the relationship of the following formula (1): AB≧10 (1) [2] The liquid chromatography column according to [1] above, wherein the mass ratio of the first fine particles (H) to the second fine particles (P) is H:P=80:20 to 20:80. [3] The liquid chromatography column according to [1] or [2], wherein the hydrophilic microparticles are at least one type of silica-based microparticles selected from the group consisting of silica gel, diol group-bonded silica gel, and amino group-bonded silica gel, or at least one type of polymer-based microparticles selected from the group consisting of polyacrylamide gel, dextran gel, polyethylene glycol gel, and polyhydroxymethacrylate gel, and the first hydrophobic microparticles and the second hydrophobic microparticles are at least one type of silica-based microparticles selected from the group consisting of octadecylsilyl group-bonded silica gel, octylsilyl group-bonded silica gel, butylsilyl group-bonded silica gel, triacontylsilyl group-bonded silica gel, phenylhexylsilyl group-bonded silica gel, and phenylsilyl group-bonded silica gel, or at least one type of polymer-based microparticles of polystyrene gel and polyethylene gel, respectively. [4] The liquid chromatography column according to [1] or [2], wherein the hydrophilic particles, the first hydrophobic particles, and the second hydrophobic particles are silica-based particles or polymer-based particles each having a chemically modified group on the surface thereof, and the chemically modified group is an alkyl group having 1 to 50 carbon atoms or an aryl group having 6 to 50 carbon atoms, in which a hydrogen atom may be substituted with a cyano group, a hydroxyl group, a carboxy group, an acid amide group, an imide group, a sulfo group, an amino group, a glyceroid group, or a halogen atom. [5] A liquid chromatography column according to any one of [1] to [4], wherein the average pore diameter (A (nm)) of the pores of the first hydrophobic microparticles is 30 to 200 nm, and the average pore diameter (B (nm)) of the pores of the second hydrophobic microparticles is 3 to 20 nm. [6] The liquid chromatography column according to any one of [1] to [5], wherein the hydrophilic particles, the first hydrophobic particles, and the second hydrophobic particles each have an average particle size of 1 to 50 μm.

[0008] Furthermore, according to the present invention, there is provided the following gas analysis method. [7] A gas analysis method comprising the steps of: passing a sample containing multiple gases through a liquid chromatography column according to any one of [1] to [6] above together with a mobile phase to separate the gases; and detecting the separated gases.

[0009] Furthermore, according to the present invention, there is provided a gas analysis system as follows. [8] A gas analysis system comprising: a liquid chromatography column according to any one of [1] to [6] above; a pressurizing mechanism for passing a sample containing multiple gases through the liquid chromatography column together with a mobile phase; and a detection unit for detecting the gases separated by the liquid chromatography column. [Effects of the Invention]

[0010] The present invention provides a liquid chromatograph column that can easily and accurately separate and analyze multiple gases in a gas mixture, and also provides a gas analysis method and gas analysis system that use the liquid chromatograph column. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an embodiment of a gas analysis system of the present invention. [Figure 2] 1 is a chromatogram showing the results of Analysis Example 1. [Figure 3] 1 is a chromatogram showing the results of Analysis Example 2. [Figure 4] 1 is a chromatogram showing the results of Analysis Example 3. [Figure 5] 1 is a chromatogram showing the results of Analysis Example 4. [Figure 6A] 1 is a chromatogram showing the results of Analysis Example 5. [Figure 6B] 1 is a chromatogram showing the results of Analysis Example 5. [Figure 6C] 1 is a chromatogram showing the results of Analysis Example 5. [Figure 7A]1 is a chromatogram showing the results of Analysis Example 6. [Figure 7B] 1 is a chromatogram showing the results of Analysis Example 6. [Figure 7C] 1 is a chromatogram showing the results of Analysis Example 6. [Figure 8] 1 is a chromatogram showing the results of Analysis Example 7. [Figure 9] 1 is a chromatogram showing the results of Analysis Example 8. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Liquid chromatographic columns> The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments. The inventors have conducted various studies on methods for easily and accurately separating and analyzing multiple gases in a gas mixture. As a result, they have found that liquid chromatography using a so-called "surface bubble modulation liquid chromatography (SBMLC) column," which is packed with hydrophobic microparticles having a large number of pores to which a gas phase is immobilized, is effective, and have arrived at the present invention. Note that this "surface bubble modulation liquid chromatography (SBMLC) column" is introduced in, for example, "Analytical Chemistry, 2015, 87, pp. 1180-1187" and "The Journal of Physical Chemistry C, 2018, 122, pp. 4409-4418," etc.

[0013] That is, the liquid chromatography column of the present invention (hereinafter also simply referred to as "column") is a liquid chromatography column filled with a packing material used for separating and analyzing gases. The packing material includes first and second microparticles. The first microparticles are at least one of hydrophilic microparticles and first hydrophobic microparticles having a large number of pores. The second microparticles are second hydrophobic microparticles having a large number of pores in which a gas phase is immobilized. When the first microparticles are first hydrophobic microparticles, the average pore diameter (A (nm)) of the pores of the first hydrophobic microparticles and the average pore diameter (B (nm)) of the pores of the second hydrophobic microparticles satisfy the relationship of the following formula (1). The column of the present invention will be described in detail below. AB≧10 (1)

[0014] (filler) The filler includes first and second microparticles. The first microparticles are at least one of (i) hydrophilic microparticles and (ii) first hydrophobic microparticles having a large number of pores. The second microparticles are second hydrophobic microparticles having a large number of pores in which a gas phase is immobilized. Both the first and second hydrophobic microparticles are hydrophobic microparticles (porous microparticles) having a large number of pores, but differ in the following respect: the average pore diameter (A (nm)) of the pores of the first hydrophobic microparticles and the average pore diameter (B (nm)) of the pores of the second hydrophobic microparticles satisfy the relationship of the following formula (1). AB≧10 (1)

[0015] The pore size of the pores of the first hydrophobic microparticles is larger than the pore size of the pores of the second hydrophobic microparticles. Thus, by combining two types of hydrophobic microparticles with different pore sizes, or by combining hydrophilic microparticles and hydrophobic microparticles (second hydrophobic microparticles), multiple gases in a mixed gas can be separated with high accuracy. If the value of "AB" is too small, the gas separation accuracy tends to decrease and the pressure range in which separation is possible tends to narrow. The average pore size (A (nm)) of the pores of the first hydrophobic microparticles and the average pore size (B (nm)) of the pores of the second hydrophobic microparticles preferably satisfy the relationship of the following formula (2), and more preferably the relationship of the following formula (3). If the value of "AB" is too large, it may be difficult to uniformly pack the packing material into a column. Therefore, from the viewpoint of ease of packing into a column, the value of "AB" is preferably 130 (nm) or less. AB≧20 (2) AB≧50 (3)

[0016] The mass ratio of the first fine particles (H) to the second fine particles (P) packed in the column is preferably H:P = 80:20 to 20:80, more preferably H:P = 70:30 to 50:50, and particularly preferably H:P = 66:34 to 50:50. By keeping the mass ratio of the first fine particles (H) to the second fine particles (P) packed in the column within the above range, multiple gases in a mixed gas can be separated with higher accuracy.

[0017] As the hydrophilic microparticles, silica-based microparticles or polymer-based microparticles can be used. Examples of silica-based microparticles that can be used as hydrophilic microparticles include at least one selected from the group consisting of silica gel, diol group-bonded silica gel, and amino group-bonded silica gel. Examples of polymer-based microparticles that can be used as hydrophilic microparticles include at least one selected from the group consisting of polyacrylamide gel, dextran gel, polyethylene glycol gel, and polyhydroxymethacrylate gel.

[0018] The first hydrophobic particles and the second hydrophobic particles can be silica-based particles or polymer-based particles, respectively. Examples of silica-based particles that can be used as the first hydrophobic particles and the second hydrophobic particles include at least one selected from the group consisting of octadecylsilyl group-bonded silica gel, octylsilyl group-bonded silica gel, butylsilyl group-bonded silica gel, triacontylsilyl group-bonded silica gel, phenylhexylsilyl group-bonded silica gel, and phenylsilyl group-bonded silica gel. Examples of polymer-based particles that can be used as the first hydrophobic particles and the second hydrophobic particles include at least one of polystyrene gel and polyethylene gel.

[0019] The hydrophilic particles, first hydrophobic particles, and second hydrophobic particles may each be silica-based particles or polymer-based particles having a chemically modified group on their surface. Examples of the chemically modified group bonded to the surface of these particles include an alkyl group having 1 to 50 carbon atoms or an aryl group having 6 to 50 carbon atoms, in which a hydrogen atom may be substituted with a cyano group, a hydroxyl group, a carboxyl group, an acid amide group, an imide group, a sulfo group, an amino group, a glyceroid group, or a halogen atom.

[0020] The average pore diameter (A (nm)) of the pores of the first hydrophobic fine particles is preferably 30 to 200 nm, more preferably 30 to 150 nm, and the average pore diameter (B (nm)) of the pores of the second hydrophobic fine particles is preferably 3 to 20 nm, more preferably 5 to 13 nm.

[0021] The average particle diameter (median diameter (D50)) of the hydrophilic particles, the first hydrophobic particles, and the second hydrophobic particles may be appropriately set depending on the conditions of liquid chromatography, etc. Specifically, the average particle diameter of the hydrophilic particles, the first hydrophobic particles, and the second hydrophobic particles may each be 1 to 50 μm, and preferably 5 to 40 μm.

[0022] (Column manufacturing method) The column of the present invention can be manufactured, for example, by the following method. First, a packing material containing first and second microparticles is packed into a column body (empty column) according to a conventional method. Next, a volatile organic solvent is passed through the column packed with the packing material to fill the voids in the column with the solvent. As the organic solvent, for example, acetone, dichloromethane, diethyl ether, or another organic solvent is preferably used. The plugs on both ends of the column body are then removed, and the column is placed in an oven and dried by moderate heating. The column is then attached to an analytical system, and pure water is passed through the column while appropriately controlling the pressure and flow rate. This results in a column of the present invention packed with a packing material containing second hydrophobic microparticles having a large number of pores in which a gas phase is immobilized.

[0023] <Gas analysis method> The gas analysis method of the present invention includes a step of passing a sample containing multiple types of gases through the above-mentioned liquid chromatographic column together with a mobile phase to separate the gases (separation step), and a step of detecting the separated gases (detection step).

[0024] (separation process) In the separation step, a sample (gas mixture) containing multiple gases is passed through the column together with a mobile phase. This allows the multiple gases in the gas mixture to be separated. Gases contained in the gas mixture include, but are not limited to, inorganic gases, organic gases, and rare gases. Water can be used as the mobile phase. Note that the water used as the mobile phase may contain various organic solvents, salts, and the like commonly used in liquid chromatography, as needed.

[0025] If necessary, the column may be heated using a column oven, etc. The procedure may be the same as that of general liquid chromatography, except that the above-mentioned column is used as a separation column and the mixed gas is used as the sample to be analyzed.

[0026] (Detection process) In the detection step, the gas separated in the column is detected. To detect the gas, a detector capable of detecting the target gas may be used. Examples of detectors that can be used include a refractive index detector (RID), a mass spectrometer (MS), and an ultraviolet detector (UV).

[0027] <Gas analysis system> Fig. 1 is a schematic diagram showing one embodiment of a gas analysis system of the present invention. The gas analysis system 100 of the embodiment shown in Fig. 1 is a system suitable for use in the above-described gas analysis method, and includes the liquid chromatographic column (column 4) described above, a pressurizing mechanism such as pump 8, and a detection unit such as detector 14. The pressurizing mechanism such as pump 8 is a mechanism for circulating a sample (gas mixture) containing multiple gases through column 4 together with mobile phase 1. The detection unit such as detector 14 is a part that detects the gases separated in column 4.

[0028] Mobile phase 1 is pressurized by pump 8 and delivered through degasser 6. The sample (gas mixture) is introduced from bag 12 into six-port valve 20 using syringe 10, and flows into column 4 together with mobile phase 1 by operating six-port valve 20. If necessary, column 4 may be heated using column oven 18. Multiple gases in the sample that flowed into column 4 are separated, flow out of column 4, and introduced into detector 14 where they are identified one by one. The remaining mobile phase 1 is then stored in waste liquid 15.

[0029] The gas analysis method of the present invention, which is carried out using the above gas analysis system, can easily separate and analyze multiple gases in a mixed gas with high accuracy. Furthermore, it can also separate argon (Ar) and oxygen (O2), which have been difficult to separate using conventional techniques. [Example]

[0030] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0031] <Preparing the filler> Various fillers of the types shown in Table 1 were prepared.

[0032] TIFF0007811362000001.tif62170

[0033] <Preparing the column> Example 1 A packing material was prepared by mixing silica 1 and ODS4 in a 1:1 mass ratio. The prepared packing material was packed into a column body with an inner diameter of 4.6 mm and a length of 250 mm according to standard procedures, and then acetone was passed through to fill the voids within the column. The plugs on both ends of the column body were then removed, and the column was placed in an oven, heated to 80°C, and dried until a constant weight was reached. The column was then attached to an analytical system. Pure water was passed through the column while controlling the pressure and flow rate, and the column was brought to equilibrium, forming a SBMLC column.

[0034] Examples 2 to 5 A column (SBMLC column) was prepared in the same manner as in Example 1 above, except that the type of packing material shown in Table 2 was used.

[0035] TIFF0007811362000002.tif101170

[0036] <Gas analysis> (Analysis example 1) The column of Example 1 (column 4) was attached to a gas analysis system 100 having the configuration shown in FIG. 1. A mixed gas containing an inorganic gas and methane was placed in bag 12. 20 μL of the mixed gas from bag 12 was injected into the system, and the mixed gas was introduced into column 4 using pure water as the mobile phase at a column temperature of 50°C and a flow rate of 3.0 mL / min, thereby separating and analyzing each gas in the mixed gas. A refractive index detector (RID) was used as detector 14. The results are shown in FIG. 2.

[0037] (Analysis example 2) Except for using a mixed gas containing argon and air, the individual gases in the mixed gas were separated and analyzed in the same manner as in the above-mentioned Analysis Example 1. The results are shown in Figure 3.

[0038] (Analysis example 3) The column of Example 2 (column 4) was attached to a gas analysis system 100 having the configuration shown in Figure 1. A mixed gas containing an inorganic gas and methane was placed in bag 12. 20 µL of the mixed gas from bag 12 was injected into the system, and the mixed gas was introduced into column 4 using pure water as the mobile phase at a column temperature of 50°C and a flow rate of 2.0 mL / min, thereby separating and analyzing each gas in the mixed gas. The results are shown in Figure 4.

[0039] (Analysis example 4) Except for using a mixed gas containing argon and air, the individual gases in the mixed gas were separated and analyzed in the same manner as in the above-mentioned Analysis Example 3. The results are shown in FIG.

[0040] (Analysis Example 5) The column of Example 3 (column 4) was attached to a gas analysis system 100 having the configuration shown in Figure 1. Air was also placed in bag 12. 20 µL of the air in bag 12 was injected into the system, and air was introduced into column 4 using pure water as the mobile phase under conditions of a column temperature of 50°C, a flow rate of 1.5 mL / min, and a pressure of 5.2 to 19.7 MPa, to separate and analyze each gas in the air. The results are shown in Figures 6A to 6C. As shown in Figures 6A to 6C, it can be seen that analysis was possible over a wide pressure range because a column with a relatively large AB value (AB = 113) was used.

[0041] (Analysis Example 6) The column of Example 4 (column 4) was attached to a gas analysis system 100 having the configuration shown in FIG. 1. Air was also placed in bag 12. 20 μL of the air in bag 12 was injected into the system, and air was introduced into column 4 using pure water as the mobile phase under conditions of a column temperature of 50°C, a flow rate of 1.5 mL / min, and a pressure of 9.6 to 15.7 MPa, to separate and analyze each gas in the air. The results are shown in FIGS. 7A to 7C. As shown in FIGS. 7A to 7C, because a column with a relatively small AB value (AB = 18) was used, the pressure range that could be suitably used was slightly narrower than in Analysis Example 5, which used a column with a relatively large AB value (AB = 113).

[0042] (Analysis Example 7) The column of Example 5 (column 4) was attached to a gas analysis system 100 having the configuration shown in FIG. 1. A mixed gas containing an inorganic gas and methane was placed in bag 12. 20 μL of the mixed gas in bag 12 was injected into the system, and the mixed gas was introduced into column 4 using pure water as the mobile phase at a column temperature of 50° C. and a flow rate of 2.0 mL / min, thereby separating and analyzing each gas in the mixed gas. The results are shown in FIG. 8.

[0043] (Analysis Example 8) Except for using a mixed gas containing argon and air, the gases in the mixed gas were separated and analyzed in the same manner as in the above-mentioned Analysis Example 7. The results are shown in FIG.

[0044] Analysis Examples 1 to 8 are summarized in Table 3.

[0045] TIFF0007811362000003.tif90170 [Industrial Applicability]

[0046] The liquid chromatographic column of the present invention is useful as a column for easily separating and analyzing a mixed gas containing a plurality of gases. [Explanation of symbols]

[0047] 1: Mobile phase 4: Column 6: Degasser 8: Pump 10: Syringe 12: Bag 14: Detector 15: Waste liquid 18: Column oven 20: 6-way valve 100: Gas analysis system

Claims

1. A liquid chromatography column packed with a packing material, used for separating and analyzing gases, comprising: the filler comprises first particulates and second particulates; the first fine particles are at least one of hydrophilic fine particles and first hydrophobic fine particles having a large number of pores, the second fine particles are second hydrophobic fine particles having a large number of pores in which a gas phase is immobilized, A liquid chromatography column in which the average pore diameter (A (nm)) of the pores of the first hydrophobic microparticles and the average pore diameter (B (nm)) of the pores of the second hydrophobic microparticles satisfy the relationship of the following formula (1): A-B≧10...(1)

2. 2. The liquid chromatography column according to claim 1, wherein the mass ratio of the first fine particles (H) to the second fine particles (P) is H:P=80:20 to 20:

80.

3. the hydrophilic microparticles are at least one type of silica-based microparticles selected from the group consisting of silica gel, diol group-bonded silica gel, and amino group-bonded silica gel, or at least one type of polymer-based microparticles selected from the group consisting of polyacrylamide gel, dextran gel, polyethylene glycol gel, and polyhydroxymethacrylate gel; 2. The liquid chromatography column according to claim 1, wherein the first hydrophobic microparticles and the second hydrophobic microparticles are at least one type of silica-based microparticles selected from the group consisting of octadecylsilyl group-bonded silica gel, octylsilyl group-bonded silica gel, butylsilyl group-bonded silica gel, triacontylsilyl group-bonded silica gel, phenylhexylsilyl group-bonded silica gel, and phenylsilyl group-bonded silica gel, or at least one polymer-based microparticle of polystyrene gel or polyethylene gel.

4. the hydrophilic fine particles, the first hydrophobic fine particles, and the second hydrophobic fine particles are silica-based fine particles or polymer-based fine particles each having a chemically modified group on the surface thereof; 2. The liquid chromatography column according to claim 1, wherein the chemical modifying group is an alkyl group having 1 to 50 carbon atoms or an aryl group having 6 to 50 carbon atoms, in which a hydrogen atom may be substituted with a cyano group, a hydroxyl group, a carboxy group, an acid amide group, an imide group, a sulfo group, an amino group, a glyceroid group, or a halogen atom.

5. the average pore diameter (A (nm)) of the pores of the first hydrophobic fine particles is 30 to 200 nm; 2. The liquid chromatography column according to claim 1, wherein the average pore diameter (B (nm)) of the pores of the second hydrophobic fine particles is 3 to 20 nm.

6. 2. The liquid chromatography column according to claim 1, wherein the hydrophilic particles, the first hydrophobic particles, and the second hydrophobic particles each have an average particle size of 1 to 50 μm.

7. A gas analysis method comprising the steps of: passing a sample containing a plurality of gases through the liquid chromatography column according to any one of claims 1 to 6 together with a mobile phase to separate the gases; and detecting the separated gases.

8. A liquid chromatographic column according to any one of claims 1 to 6; a pressurizing mechanism for causing a sample containing a plurality of gases to flow through the liquid chromatograph column together with a mobile phase; a detection unit that detects the gas separated by the liquid chromatography column; A gas analysis system comprising:

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