Detectors for liquid chromatography

Abstract

A detector for a liquid chromatograph. The present invention uses a flow cell composed of a liquid contact component containing a non-metallic material, and charges are easily released from the flow cell. The detector for a liquid chromatograph of the present invention is a detector for a liquid chromatograph (50) that allows the mobile phase and the sample that have passed through the column (10) of the liquid chromatograph (100) to flow into the flow cell (52) via a pipe (56), and detects the components in the sample flowing in the flow cell, wherein the pipe is composed of a first liquid contact component (56) containing a PEEK resin material, and the flow path surface of the flow cell (52) is composed of a second liquid contact component (521), and the second liquid contact component (521) contains a non-metallic material with a resistivity smaller than that of the first liquid contact component.

Description

Technical Field

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

[0002] Generally, in detectors used for liquid chromatography analysis, metal materials such as stainless steel with excellent corrosion resistance and chemical resistance are often used as materials for piping or flow cells for mobile phase and sample eluted from the separation column of the liquid chromatograph. However, most of the samples used for liquid chromatography analysis in the fields of biology, medicine, and pharmacy are easily adsorbed on metals such as stainless steel. Therefore, a detector is provided in which the portion of piping or flow cells that contacts the mobile phase and sample (called a liquid contact member) is formed of a non-metallic material.

[0003] As one of the non-metallic materials used for liquid contact components, there is polyetheretherketone (PEEK) resin (Patent Document 1). PEEK resin has excellent corrosion resistance and chemical resistance, and has higher strength than general resins. However, compared with metals, the overall resistance of the resin is very large, about 10 15 Ω·m.

[0004] It is known that when liquid flows at high speed in a pipe, static electricity is generated due to friction between the inner surface of the pipe and the liquid, and a phenomenon called flow charging occurs in which the inner surface of the pipe is charged. In the case of a pipe made of stainless steel with low electrical resistance, even if flow charging occurs and the inner surface of the pipe is charged, the charge is quickly released to the outside of the pipe. However, if the liquid contacting member of the pipe is formed of a PEEK resin material with high electrical resistance, it is difficult to release the charge to the outside of the pipe, so the charge accumulates on the inner surface of the pipe, and a part of it flows into the circulation pool together with the liquid passing through the pipe.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2010-066158 Summary of the invention

[0008] [Problems to be solved by the invention]

[0009] When a UV-visible spectrophotometer is used as a detector for a liquid chromatograph, which detects sample components in a flow cell by irradiating UV light or visible light into the flow cell to measure absorbance, a light receiving element is arranged near the flow cell in order to accurately detect the amount of light passing through the flow cell. If the light receiving element is close to the flow cell, there is a problem that the shape of the chromatogram created based on the output signal of the light receiving element is destroyed due to the influence of noise (also called electrostatic noise) caused by the charge flowing into the flow cell.

[0010] The problem to be solved by the present invention is to use a flow cell composed of a liquid contact member made of a non-metallic material and to facilitate the release of electric charges from the flow cell.

[0011] [Technical means to solve the problem]

[0012] The present invention completed in order to solve the above-mentioned problem is a detector for a liquid chromatograph, which allows a mobile phase and a sample that have passed through a column of a liquid chromatograph to flow into a flow cell via a pipe, and detects components in the sample flowing in the flow cell, wherein:

[0013] The pipe is formed by using a first liquid contact member made of PEEK resin material.

[0014] The flow path surface of the flow cell is formed using a second liquid-contacting member including a non-metallic material having a lower resistivity than the first liquid-contacting member.

[0015] [Effects of the Invention]

[0016] According to the detector for liquid chromatograph of the present invention, even when a sample is analyzed by liquid chromatograph in the fields of biology, medicine, and pharmacy, it is possible to suppress the components in the sample from being adsorbed to the inner surfaces of the liquid contact members of the pipes and the flow cell when the sample passes through the pipes together with the mobile phase. In addition, even when the sample flows in the pipes together with the mobile phase, flow electrification is generated in the pipes and the charge flows into the flow cell, since the resistivity of the liquid contact member of the flow cell is small, the charge in the flow cell can be easily released by grounding the liquid contact member. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic configuration diagram of a liquid chromatograph including a detector for liquid chromatograph according to one embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of a detector for liquid chromatography.

[0019] Figure 3This is a chromatogram showing an example in which the same sample is actually measured using the detector for liquid chromatograph according to the present embodiment and a conventional detector for liquid chromatograph.

[0020] [Explanation of Symbols]

[0021] 10: String

[0022] 100: Liquid chromatography device

[0023] 50: Detector

[0024] 51: Frame

[0025] 52: Circulation cell

[0026] 521: Pool shell

[0027] 522: Light Path

[0028] 5221, 5222: Light path components

[0029] 523: Flow path

[0030] 524: Pool bracket

[0031] 55: Detection element

[0032] 56, 57: Piping DETAILED DESCRIPTION

[0033] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0034] Figure 1 It is a schematic configuration diagram of a liquid chromatograph device including a detector for liquid chromatograph (hereinafter referred to as a detector) according to the present embodiment.

[0035] The liquid chromatograph device 100 includes: a column 10 for component separation, which is arranged inside a column oven 11; a liquid delivery pump 30, which sucks a mobile phase from a mobile phase container 20 and delivers it to the column 10; an injector 40, which injects a sample into the mobile phase delivered to the column 10 by the liquid delivery pump 30; a detector 50, which detects the components in the eluent eluted from the outlet of the column 10; a pipe 61 connecting the liquid delivery pump 30 to the inlet end of the column 10, and a pipe 62 connecting the outlet end of the column 10 to the detector 50. The liquid passing through the detector 50 is discharged to the drain container 70 as waste liquid via a pipe 63.

[0036] The detector 50, for example, includes a visible ultraviolet spectrophotometer, and includes: a frame 51; a flow cell 52 arranged in the frame 51; a light source 53 that emits visible light or ultraviolet light; a spectrometer 54 that splits 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.

[0037] Figure 2 : is a schematic structural diagram of the flow cell 52. The flow cell 52 comprises: a cell housing 521, which is in a cubic shape and contains a PEEK resin material containing carbon fibers (hereinafter referred to as a carbon-containing PEEK resin material); an optical path 522, which is arranged inside the cell housing 521 and passes through the cell housing 521; and a flow path 523, through which the eluent from the column 10 delivered via the piping 62 flows; and a cell bracket 524, which is made of metal and is respectively arranged above and below the cell housing 521, and is used to fix the cell housing 521 to the frame 51. Since the frame 51 is grounded, the cell housing 521 is also grounded by fixing the metal cell bracket 524 to the frame 51.

[0038] Flow path 523 includes a cavity that penetrates through the cell housing 521 in a U-shape, and both ends are located on the surface (lower surface in the figure) of the same side of the cell housing 521. Pipes 56 and pipes 57 are connected to the two ends of flow path 523 respectively. Pipes 56 are connected to pipes 62, and pipes 57 are connected to pipes 63. Pipes 56 and pipes 57 both contain PEEK resin material. In the present embodiment, the carbon-containing PEEK resin material used as the material of the cell housing 521 uses a material with a lower resistance value than the PEEK resin material used as the material of the pipes 56 and pipes 57. In addition, pipes 56 and pipes 57 are equivalent to the first liquid contact member, and the cell housing 521 is equivalent to the second liquid contact member.

[0039] The middle portion 5231 of the flow path 523 extends in a straight line, and the portion of the middle portion 5231 from one end to the end on the piping 62 side and the portion of the middle portion 5231 from the other end to the end on the piping 63 side extend in a direction perpendicular to the middle portion 5231.

[0040] In the cell housing 521, from one end and the other end of the middle portion 5231 of the flow path 523 to the two end faces facing each other of the cell housing 521, a cavity having the same cross-sectional shape as the middle portion 5231 is provided, and a glass light path member 5221 and a glass light path member 5222 are respectively embedded. The light path member 5221, the middle portion 5231, and the light path member 5222 are arranged in a straight line, and the light path 522 is constituted by these light path members 5221, the middle portion 5231, and the light path member 5222. That is, a part of the light path 522 overlaps with the middle portion 5231 of the flow path 523.

[0041] With respect to the flow cell 52 of the structure, the light source 53 and the beam splitter 54 are arranged so that the light emitted from the beam splitter 54 is as follows: Figure 2 As shown by the middle arrow 80, after entering the light path member 5221, the light travels straight in the light path 522 and is emitted from the light path member 5222. In addition, the detection element 55 is arranged near the light path member 5222, and the light emitted from the light path member 5222 is incident thereon.

[0042] The eluent delivered from the column 10 via the pipe 62 flows through the flow path 523 via the pipe 56, and is discharged to the drain container 70 via the pipes 57 and 63. At this time, the light incident on the light path member 5221 from the spectrometer 54 passes through the middle portion 5231 of the flow path 523 and is emitted from the light path member 5222, so the intensity of the light incident on the detection element 55 corresponds to the absorbance of the eluent flowing through the middle portion 5231.

[0043] In the present embodiment, the materials of the cell housing 521, the piping 56, and the piping 57 are all PEEK resin materials, so it is possible to prevent the components of the sample contained in the eluent from being adsorbed on the inner surface of the flow path 523, the inner surface of the piping 56, and the piping 57. In addition, since the resistivity of the carbon-containing PEEK resin material constituting the cell housing 521 is lower than the resistivity of the PEEK resin material constituting the piping 56 and the piping 57, even if the eluent generates flow electrification in the piping 56 when flowing in the piping 56, and the charge flows into the flow path 523, the charge can be released to the outside via the cell housing 521 and the cell holder 524. Therefore, the influence of electrostatic noise, which has been a conventional problem, on the detection element can be suppressed.

[0044] Figure 3 An example of a chromatogram obtained as a result of allowing only acetonitrile as a mobile phase to flow into a column using the liquid chromatograph apparatus 100 of the present embodiment is shown. Figure 3 (1) is to use a resistivity of 10 3 Ω·m~10 5 Ω·m, (2) is a chromatogram of a cell housing 521 made of a carbon-containing PEEK resin material having a resistivity of about 10 15 Ω·m PEEK resin cell housing 521 when the chromatogram. Figure 3 It can be seen that when a cell case with a small resistivity is used, noise is reduced and the destruction of the chromatogram is suppressed.

[0045] In addition, in the embodiment, the whole of the cell housing 521 is formed by a carbon-containing PEEK resin material, but as long as the components constituting the inner peripheral surface of the flow path, that is, the components connected to the cell support (i.e., the liquid contact components) are formed by carbon-containing PEEK resin materials. In addition, the cell housing 521 can also be connected to the frame or the ground wire without being connected to the cell support and grounded. Furthermore, both the piping 56 and the piping 57 are formed by PEEK resin materials, but as long as at least the piping 56 is formed by PEEK resin materials, and further, as long as the components constituting the inner peripheral surface of the piping 56 (i.e., the liquid contact components) are at least formed by PEEK resin materials.

[0046] It should be understood that the above-described embodiments and modifications are examples of the present invention, and that appropriate corrections, changes, and additions made within the scope of the gist of the present invention other than the above-described contents are also included in the scope of the claims of the present application.

[0047] [Various methods]

[0048] In addition, it can be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following aspects.

[0049] (Item 1) The present invention is a detector for a liquid chromatograph, which allows a mobile phase and a sample that have passed through a column of a liquid chromatograph to flow into a flow cell via a pipe, and detects components in the sample flowing in the flow cell, wherein:

[0050] The pipe is formed by using a first liquid contact member made of PEEK resin material.

[0051] The flow path surface of the flow cell is formed using a second liquid-contacting member including a non-metallic material having a lower resistivity than the first liquid-contacting member.

[0052] In the detector for liquid chromatograph of the first item, even when a sample is analyzed by liquid chromatography in the fields of biology, medicine, and pharmacy, the components in the sample will not be adsorbed to the inner surfaces of the liquid contact members of the pipes and the flow cell when the sample passes through the pipes and the flow cell together with the mobile phase. In addition, even when flow electrification is generated in the pipes when the sample flows in the pipes together with the mobile phase, and the charge flows into the flow cell, since the resistivity of the liquid contact member of the flow cell is small, the charge in the flow cell can be easily released by grounding the liquid contact member.

[0053] (Item 2) The detector for liquid chromatograph according to Item 1 may include an ultraviolet-visible spectrophotometer for projecting visible light or ultraviolet light into the flow cell to measure absorbance.

[0054] The UV-visible spectrophotometer measures absorbance by detecting the intensity of visible light or ultraviolet light projected into and passing through a flow cell using a predetermined light-receiving element. In the UV-visible spectrophotometer, in order to accurately measure the intensity of visible light or ultraviolet light passing through the flow cell, the light-receiving element is usually arranged near the flow cell. Therefore, if electric charges accumulate in the flow cell, the influence of the noise caused by the electric charges spreads to the light-receiving element, and the intensity of the visible light or ultraviolet light cannot be accurately measured. In contrast, in the detector for liquid chromatograph in the second item, since the electric charges flowing into the flow cell can be released, the noise caused by the electric charges can be eliminated.

[0055] (Item 3) In the detector for liquid chromatograph according to Item 1 or Item 2,

[0056] The non-metal material may be a PEEK resin material containing carbon fibers.

[0057] The resistance value of conventional PEEK resin is about 10 15 Ω·m, on the other hand, the resistance value of PEEK resin containing carbon fiber depends on the content of carbon fiber, but the resistance value of PEEK resin containing carbon fiber on the market is generally 10 8 Ω·m or less. The PEEK resin containing carbon fibers (hereinafter referred to as the carbon-containing PEEK resin material) has the same properties as the existing PEEK resin, such as high chemical resistance and high strength. Therefore, by using the liquid contact member containing the carbon-containing PEEK resin material to form a flow cell, a flow cell that is easy to release charge and has high chemical resistance and high strength can be formed.

[0058] Here, the PEEK resin material of the liquid contact member (first liquid contact member) of the pipe may contain carbon fibers as long as the PEEK resin material has a larger electrical resistance than the second liquid contact member of the flow cell.

[0059] (Item 4) In the detector for liquid chromatograph of Item 3,

[0060] The non-metallic material can be set to have a resistance value of 10 5 PEEK resin material containing carbon fiber with a resistance of less than Ω·m.

[0061] By using a resistor value of 10 5 The second liquid contact member is made of a PEEK resin material containing carbon fibers with a resistance of Ω·m or less, which makes it easier to release the charge in the flow cell.

[0062] (Item 5) In the detector for liquid chromatograph according to Item 3 or Item 4,

[0063] The non-metal material may be a PEEK resin material containing carbon fibers, the content of which is 10% or less.

[0064] By using a carbon fiber-containing PEEK resin material having a carbon fiber content of 10% or less as the material of the second liquid contact member, adsorption of components in the sample to the second liquid contact member can be suppressed, and a second liquid contact member with low resistivity can be realized.

[0065] (Item 6) In the detector for liquid chromatograph according to any one of Items 1 to 5,

[0066] The entire flow path surface may be formed using a second liquid contacting member made of the non-metallic material.

[0067] According to the detector for liquid chromatograph of claim 6, the electric charge flowing into the flow cell can be efficiently released to the outside via the second liquid contact member constituting the entire flow path surface.

[0068] (Item 7) The detector for liquid chromatograph according to any one of Items 1 to 6 may further include:

[0069] a frame; and

[0070] a cell support, which contacts the second liquid-contacting member and is made of metal, and

[0071] The cell support is in contact with the frame.

[0072] According to the detector for liquid chromatograph of item 7, the electric charge flowing into the flow cell can be released to the frame via the second liquid contact member and the cell holder.

Claims

1. A detector for liquid chromatograph, characterized in that: The mobile phase and the sample that have passed through the column of the liquid chromatograph are flowed into the flow cell through the pipe, and the components in the sample flowing in the flow cell are detected. In the detector for the liquid chromatograph, The pipe is formed by using a first liquid contact member made of a polyetheretherketone resin material. The flow path surface of the flow cell is formed using a second liquid-contacting member including a non-metallic material having a lower resistivity than the first liquid-contacting member.

2. The detector for liquid chromatograph according to claim 1, wherein: A UV-visible spectrophotometer is included for projecting visible light or UV light into the flow cell to measure absorbance.

3. The detector for liquid chromatograph according to claim 1 or 2, wherein: The non-metal material is a polyetheretherketone resin material containing carbon fiber.

4. The detector for liquid chromatograph according to claim 3, wherein: The non-metallic material is a polyetheretherketone resin material containing carbon fiber, and its resistance value is 10 5 Ω·m or less.

5. The detector for liquid chromatograph according to claim 3, wherein: The non-metallic material includes a carbon-containing polyetheretherketone resin material having a carbon content of 10% or less.

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

7. The detector for liquid chromatograph according to claim 1, comprising: a frame; and a cell support, which contacts the second liquid-contacting member and is made of metal, and The cell support is in contact with the frame.

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