Liquid chromatograph detector

Abstract

To easily discharge electric charges from the inside of a flow cell composed of a liquid contact member composed of a non-metal material, while using the flow cell.SOLUTION: A detector 50 for a liquid chromatograph 100 in the present invention flows a mobile phase and a sample passing through a column 10 of the liquid chromatograph 100 to a flow cell 52 through a pipe 56, and detects a component in the sample flowing in the flow cell, wherein the pipe is composed using a first liquid contact member 56 composed of a PEEK resin material, and a flow channel surface of the flow cell 52 is composed using a second liquid contact member 521 containing a non-metal material having electric resistivity smaller than that of the first liquid contact member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a detector for a liquid chromatograph. [Background technology]

[0002] Typically, in detectors used in liquid chromatographic analysis, metal materials such as stainless steel, which have excellent corrosion resistance and chemical resistance, are often used as materials for the piping and flow cells through which the mobile phase and sample eluted from the separation column of the liquid chromatograph flow. However, since many of the samples used in liquid chromatographic analysis in the fields of biology, medicine, pharmacy, etc. are easily adsorbed by metals such as stainless steel, detectors are being developed in which the parts of the piping and flow cell that come into contact with the mobile phase and sample (called liquid-contacting parts) are made of non-metallic materials.

[0003] One of the non-metallic materials used for wetted parts is PEEK (polyether ether ketone) resin (Patent Document 1). PEEK resin has excellent corrosion resistance and chemical resistance, and is stronger than general resins. However, compared to metals, resins generally have an electrical resistance of about 10 15 It is very large at Ω·m.

[0004] It is known that when a liquid flows through a pipe at high speed, friction between the inner surface of the pipe and the liquid generates static electricity, charging the inner surface of the pipe, a phenomenon known as flow electrification. If the pipe is made of stainless steel, which has low electrical resistance, even if flow electrification occurs and charges the inner surface of the pipe, the charge is quickly released outside the pipe. However, if the liquid-contacting parts of the pipe are made of PEEK resin, which has high electrical resistance, the charge is difficult to release outside the pipe, so the charge accumulates on the inner surface of the pipe, and some of it flows into the flow cell along with the liquid passing through the pipe. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-066158 Summary of the Invention [Problem to be solved by the invention]

[0006] When a UV-visible spectrophotometer is used as a detector for a liquid chromatograph, which irradiates the inside of a flow cell with UV or visible light and measures the absorbance to detect the sample components in the flow cell, a light-receiving element is placed near the flow cell to accurately detect the amount of light that has passed through the flow cell. If the light-receiving element and the flow cell are placed too close to each other, there is a problem in that the shape of the chromatogram created based on the output signal of the light-receiving element is distorted by the influence of noise (also known as electrostatic noise) caused by electric charges that have flowed into the flow cell.

[0007] The problem to be solved by the present invention is to make it easier to release electric charges from within a flow cell while using a flow cell made of a liquid-contacting member made of a non-metallic material. [Means for solving the problem]

[0008] The present invention, which has been made to solve the above problems, is a liquid chromatograph detector that allows a mobile phase and a sample that have passed through a column of a liquid chromatograph to flow through a piping into a flow cell, and detects components in the sample flowing through the flow cell, comprising: The piping is configured using a first liquid contact member made of a PEEK resin material, The flow channel surface of the flow cell is configured using a second liquid contact member containing a non-metallic material having a lower electrical resistivity than the first liquid contact member. [Effects of the Invention]

[0009] The liquid chromatograph detector of the present invention can suppress adsorption of components in the sample to the inner surfaces of the liquid-contacting members when the components pass through the piping and flow cell together with the mobile phase, even when samples are analyzed using liquid chromatographic analysis in the fields of biology, medicine, and pharmacy. Furthermore, even if flow electrification occurs in the piping when the sample flows through the piping together with the mobile phase and charges flow into the flow cell, the electric charge in the flow cell can be easily released by grounding the liquid-contacting members because the electric resistivity of the liquid-contacting members of the flow cell is low. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a liquid chromatograph including a liquid chromatograph detector according to one embodiment of the present invention; [Figure 2] Schematic diagram of a liquid chromatograph detector. [Figure 3] 1 is a chromatogram showing an example of actual measurement of the same sample using the liquid chromatograph detector of this embodiment and a conventional liquid chromatograph detector. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a liquid chromatograph device including a liquid chromatograph detector (hereinafter referred to as a detector) according to this embodiment. Overview FIG.

[0012] The liquid chromatograph 100 includes a column 10 for separating components installed inside a column oven 11, a liquid delivery pump 30 that draws mobile phase from a mobile phase container 20 and delivers it to the column 10, an injector 40 that injects a sample into the mobile phase delivered to the column 10 by the liquid delivery pump 30, a detector 50 that detects components in the eluate eluted from the outlet of the column 10, and pipes 61 and 62 that connect the liquid delivery pump 30 to the inlet end of the column 10 and the outlet end of the column 10 to the detector 50, respectively. The liquid that has passed through the detector 50 is discharged as waste liquid into a drain container 70 via pipe 63.

[0013] The detector 50 is, for example, a visible-ultraviolet spectrophotometer, and includes a housing 51, a flow cell 52 arranged in the housing 51, a light source 53 that emits visible light or ultraviolet light, a spectroscope 54 that disperses the light emitted from the light source 53 and projects it into the flow cell 52, and a detection element 55 that detects the light that has passed through the flow cell 52.

[0014] 2 is a schematic diagram of the flow cell 52. The flow cell 52 has a cubic cell housing 521 made of a PEEK resin material containing carbon fiber (hereinafter referred to as a carbon-containing PEEK resin material), an optical path 522 penetrating the cell housing 521 provided inside the cell housing 521, a flow path 523 through which the eluate from the column 10 sent via the piping 62 flows, and metal cell holders 524 provided above and below the cell housing 521 for fixing the cell housing 521 to the housing 51. Since the housing 51 is grounded, the cell housing 521 is also grounded by being fixed to the housing 51 by the metal cell holders 524.

[0015] The flow path 523 is formed of a U-shaped cavity penetrating the cell housing 521, and both ends are located on the same surface of the cell housing 521 (the bottom surface in the drawing). Pipes 56 and 57 are connected to both ends of the flow path 523, respectively. Pipe 56 is connected to pipe 62, and pipe 57 is connected to pipe 63. Pipes 56 and 57 are both made of PEEK resin material. In this embodiment, the carbon-containing PEEK resin material used for the cell housing 521 has a lower electrical resistance than the PEEK resin material used for the pipes 56 and 57. Furthermore, pipes 56 and 57 correspond to a first liquid-contacting member, and the cell housing 521 corresponds to a second liquid-contacting member.

[0016] The flow path 523 has a middle portion 5231 that extends linearly, and the portion from one end of the middle portion 5231 to the end on the piping 62 side and the portion from the other end of the middle portion 5231 to the end on the piping 63 side extend in a direction perpendicular to the middle portion 5231.

[0017] Within the cell housing 521, cavities having the same cross-sectional shape as the intermediate portion 5231 are provided in the areas from one end and the other end of the intermediate portion 5231 of the flow path 523 to the two opposing end faces of the cell housing 521, and glass light path members 5221, 5222 are fitted into these cavities. The light path member 5221, the intermediate portion 5231, and the light path member 5222 are aligned in a straight line, and the light path 522 is composed of the light path member 5221, the intermediate portion 5231, and the light path member 5222. In other words, a portion of the light path 522 overlaps with the intermediate portion 5231 of the flow path 523.

[0018] In the flow cell 52 having the above configuration, the light source 53 and the spectroscope 54 are arranged so that light emitted from the spectroscope 54 enters the light path member 5221, travels straight through the light path 522, and exits from the light path member 5222, as shown by the arrow 80 in Fig. 2. The detection element 55 is also arranged near the light path member 5222, and the light emitted from the light path member 5222 enters the detection element 55.

[0019] The eluate sent from column 10 through pipe 62 flows through pipe 56 in flow path 523 and is discharged into drain container 70 through pipes 57 and 63. At this time, light incident on light path member 5221 from spectroscope 54 passes through intermediate portion 5231 of flow path 523 and then exits from light path member 5222. Therefore, the intensity of the light incident on detection element 55 corresponds to the absorbance of the eluate flowing through intermediate portion 5231.

[0020] In this embodiment, the cell housing 521 and the pipes 56 and 57 are all made of PEEK resin material, which prevents components of the sample contained in the eluate from being adsorbed onto the inner surface of the flow channel 523 and the inner surfaces of the pipes 56 and 57. In addition, the carbon-containing PEEK resin material that makes up the cell housing 521 has lower electrical resistance than the PEEK resin material that makes up the pipes 56 and 57, which prevents the eluate from adsorbing onto the inner surface of the flow channel 523 and the inner surfaces of the pipes 56 and 57. 56 When flowing through the pipe 56 Even if flow electrification occurs within the cell and the charge flows into the flow path 523, the charge can be discharged to the outside through the cell housing 521 and the cell holder 524. Therefore, the influence of static electricity noise on the detection element, which was a conventional problem, can be suppressed.

[0021] 3 shows an example of a chromatogram obtained by passing only acetonitrile, which is a mobile phase, through a column using the liquid chromatograph 100 of this embodiment. 3 ~10 5 Chromatogram (2) shows the results when using a cell housing 521 made of carbon-containing PEEK resin material with an electrical resistivity of approximately 10 15 This is a chromatogram obtained when using a cell housing 521 made of PEEK resin material with an electrical resistivity of Ω·m. Figure 3 shows that using a cell housing with a low electrical resistivity reduces noise and suppresses the collapse of the chromatogram.

[0022] In the above embodiment, the entire cell housing 521 is formed from a carbon-containing PEEK resin material, but it is sufficient that the member constituting the inner circumferential surface of the flow path and in contact with the cell holder (i.e., the liquid-contacting member) is formed from a carbon-containing PEEK resin material. The cell housing 521 may be connected to the housing or earth without the cell holder for grounding. Furthermore, although both the pipe 56 and the pipe 57 are formed from a PEEK resin material, it is sufficient that at least the pipe 56 is formed from a PEEK resin material, and further, it is sufficient that at least the member constituting the inner circumferential surface of the pipe 56 (i.e., the liquid-contacting member) is formed from a PEEK resin material.

[0023] Furthermore, the above-mentioned embodiments and variations are merely examples of the present invention, and it is clear that any modifications, changes, or additions made within the spirit of the present invention other than those described above will also be encompassed within the scope of the claims of the present application.

[0024] [Various aspects] It will also be understood by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects.

[0025] (Item 1) The present invention provides a liquid chromatograph detector in which a mobile phase and a sample that have passed through a column of a liquid chromatograph are passed through a piping to a flow cell, and components in the sample flowing through the flow cell are detected, The piping is configured using a first liquid contact member made of a PEEK resin material, The flow channel surface of the flow cell is configured using a second liquid contact member containing a non-metallic material having a lower electrical resistivity than the first liquid contact member.

[0026] With the liquid chromatography detector of paragraph 1, even when samples are analyzed using liquid chromatography in the fields of biology, medicine, and pharmacy, components in the sample are not adsorbed to the inner surfaces of the liquid-contacting parts of the piping and flow cell as they pass through them together with the mobile phase. Furthermore, even if flow electrification occurs in the piping when the sample flows through the piping together with the mobile phase and charges flow into the flow cell, the electrical resistivity of the liquid-contacting parts of the flow cell is low, so the charges in the flow cell can be easily released by grounding the liquid-contacting parts.

[0027] (Item 2) The liquid chromatograph detector of item 1 may be equipped with an ultraviolet-visible spectrophotometer that projects visible light or ultraviolet light into the flow cell to measure absorbance.

[0028] UV-visible spectrophotometers measure absorbance by projecting visible or ultraviolet light into a flow cell and detecting the intensity of the light that passes through the flow cell using a specified light-receiving element. In UV-visible spectrophotometers, the light-receiving element is typically placed near the flow cell to accurately measure the intensity of the visible or ultraviolet light that passes through the flow cell. Therefore, if charge accumulates in the flow cell, the charge-induced noise affects the light-receiving element, preventing accurate measurement of the intensity of the visible or ultraviolet light. In contrast, the liquid chromatograph detector described in Section 2 can release the charge that flows into the flow cell, eliminating the charge-induced noise.

[0029] (Item 3) In the liquid chromatograph detector of items 1 or 2, The non-metallic material may be a PEEK resin material containing carbon fiber.

[0030] Conventional PEEK resin has an electrical resistance of approximately 10 15 Ω·m, whereas PEEK resin containing carbon fiber has an electrical resistance of 10 8The electrical resistance is Ω·m or less. PEEK resin containing carbon fiber (hereinafter referred to as carbon-containing PEEK resin material) has the same properties as conventional PEEK resin, such as high chemical resistance and high strength, so by constructing a flow cell using liquid-contacting members made of carbon-containing PEEK resin material, it is possible to create a flow cell that is easy to release electric charge and has excellent chemical resistance and strength. Here, the PEEK resin material of the liquid contact member (first liquid contact member) of the piping may contain carbon fiber, as long as it has a higher electrical resistance value than the second liquid contact member of the flow cell.

[0031] (4) In the liquid chromatograph detector of 3, The non-metallic material has an electrical resistance of 10 5 The material may be a PEEK resin material containing carbon fiber with a strength of Ω·m or less.

[0032] Electrical resistance is 10 5 By constructing the second liquid contact member from a PEEK resin material containing carbon fibers with a resistance of Ω·m or less, it becomes easier to release the electric charge inside the flow cell.

[0033] (5) In the liquid chromatograph detector of paragraph 3 or 4, The non-metallic material may be made of a PEEK resin material containing carbon fibers, with the carbon fiber content being 10% or less.

[0034] By using a PEEK resin material containing carbon fiber with a carbon fiber content of 10% or less as the material for the second liquid contact member, it is possible to realize a second liquid contact member with low electrical resistivity while suppressing adsorption of components in the sample onto the second liquid contact member.

[0035] (Item 6) In the liquid chromatograph detector according to any one of items 1 to 5, The entire surface of the flow path may be configured using the second liquid contact member made of the non-metallic material.

[0036] According to the liquid chromatograph detector of item 6, the electric charge that has flowed into the flow cell can be efficiently discharged to the outside through the second liquid contact member that constitutes the entire surface of the flow path.

[0037] (Item 7) The liquid chromatograph detector according to any one of items 1 to 6 further comprises: The housing and a cell holder made of metal and in contact with the second liquid contact member; The cell holder may be in contact with the housing.

[0038] According to the liquid chromatograph detector of item 7, the electric charge that has flowed into the flow cell can be released to the housing through the second liquid contact member and the cell holder. [Explanation of symbols]

[0039] 10...Column 100...Liquid chromatograph 50...detector 51...Case 52...Flow cell 521...Cell housing 522...Light passage 5221, 5222...Light path members 523...Flow path 524...Cell holder 55...Detection element 56,57...Piping

Claims

1. A liquid chromatograph detector in which a mobile phase and a sample that have passed through a column of a liquid chromatograph are passed through a piping into a flow cell, and components in the sample flowing through the flow cell are detected, the piping is configured using a first liquid contact member made of a PEEK resin material, A liquid chromatograph detector, wherein the flow path surface of the flow cell is configured using a second liquid contact member containing a non-metallic material having a lower electrical resistivity than the first liquid contact member.

2. 2. The liquid chromatograph detector according to claim 1, further comprising an ultraviolet-visible spectrophotometer that projects visible or ultraviolet light into the flow cell to measure absorbance.

3. 3. The liquid chromatograph detector according to claim 1, A liquid chromatograph detector, wherein the non-metallic material is a PEEK resin material containing carbon fiber.

4. 4. The liquid chromatograph detector according to claim 3, The non-metallic material is a PEEK resin material containing carbon fiber, and its electrical resistance is 10 ５ A liquid chromatograph detector having a resistance of Ω·m or less.

5. 5. The liquid chromatograph detector according to claim 3, A liquid chromatograph detector, wherein the second liquid contact member is made of a carbon-containing PEEK resin material having a carbon content of 10% or less.

6. 6. The liquid chromatograph detector according to claim 1, wherein the entire surface of the flow path is formed using the second liquid contact member made of the non-metallic material.

7. The housing and a cell holder made of metal and in contact with the second liquid contact member; 7. The liquid chromatograph detector according to claim 1, wherein the cell holder is in contact with the housing.

8. 8. The liquid chromatograph detector according to claim 1, wherein the second liquid contact member is grounded.

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