JP7180786B2 - Flow cells for chromatography detectors and chromatography detectors - Google Patents

Description

The present invention relates to flow cells for chromatographic detectors and chromatographic detectors.

Chromatographs such as liquid chromatographs (LC) and supercritical fluid chromatographs (SFC) are known as apparatuses for separating substances contained in a sample into different components. In particular, SFC uses a supercritical fluid with low viscosity and high diffusivity as a mobile phase, so it is possible to analyze samples at high speed.

In the SFC described in Patent Document 1, liquefied carbon dioxide is supplied as a mobile phase to a mobile phase channel, and a sample is injected into the mobile phase channel. The mobile phase and sample pass through a separation column arranged in the mobile phase flow path. Here, the pressure in the mobile phase channel is maintained by the back pressure valve and the temperature of the separation column is maintained by the column oven so that the mobile phase is in a supercritical state at least in the separation column. The sample that has passed through the separation column is separated into individual sample components and detected by a detector.
JP 2016-173343 A JP 2014-41024 A

The temperature coefficient of refractive index or pressure coefficient of the supercritical fluid used as the mobile phase in SFC is larger than the temperature coefficient of refractive index or pressure coefficient of water used as the mobile phase in LC. Therefore, in SFC, the refractive index of the mobile phase changes significantly due to changes in pressure or temperature. Therefore, when an absorbance detector is used as the detector, the amount of transmitted light changes as the refractive index of the mobile phase flowing through the flow cell changes. In this case, the baseline of the chromatogram fluctuates greatly, which reduces the precision of the analysis.

In LC, by using a flow cell (light guide cell) containing a capillary inside, it is possible to suppress variations in the baseline of the chromatogram due to changes in the refractive index of the mobile phase (for example, patent Reference 2). However, in SFC, since the inside of the detector is maintained at a high pressure, it is not easy to provide the above light guide cell. In addition, if the thickness of the wall surface of the capillary is increased in order to increase the withstand voltage of the light guide cell, the amount of light transmitted through the wall surface increases, which may reduce the accuracy of quantitative analysis.

An object of the present invention is to provide a flow cell for a chromatographic detector and a chromatographic detector that can be used for highly accurate analysis.

An embodiment according to one aspect of the present invention is a flow cell for a chromatography detector used to generate a chromatogram of a sample, comprising: a main body having an inner space extending in one direction; an annular capillary that is housed so as to extend and forms a flow channel through which the mobile phase containing the sample flows, the capillary includes a wall surface having a thickness that does not deform under a pressure of 8 MPa, and intersects the one direction; a first value, which is the area of the region enclosed by the outer edge of the wall of the capillary in a cross-section through the cross-section, and the area of the region between the outer edge and the inner edge of the wall of the capillary, in the cross-section wherein a second value is defined and the upper limit of said wall thickness is restricted such that the ratio of said second value to said first value is 0.8 or less.

An embodiment according to another aspect of the present invention includes the above-described flow cell for a chromatography detector, a light projecting section for emitting light to a mobile phase containing a sample flowing through the channel of the flow cell for a chromatography detector, and light emitted by the light projecting section. The present invention relates to a chromatography detector comprising a light-receiving section that receives light transmitted through a sample and outputs a signal indicating the amount of received light.

INDUSTRIAL APPLICABILITY According to the present invention, a flow cell for chromatography detector can be used for highly accurate analysis.

FIG. 1 is a diagram showing the configuration of a chromatograph including a chromatography detector according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of the detector in FIG. 3 is a schematic partial cross-sectional view showing the structure of the flow cell of FIG. 2. FIG. FIG. 4 is a cross-sectional view of the capillary of FIG. 3 taken along the line AA. FIG. 5 is a diagram showing the dimensions of capillaries in Example 1, Example 2 and Comparative Example 1. FIG. FIG. 6 is a diagram showing the relationship between the flow cell area ratio and the measured linearity error. 7 is a diagram showing the baseline of the chromatogram in Example 4. FIG. 8 is a diagram showing the baseline of the chromatogram in Comparative Example 2. FIG.

(1) Configuration of Chromatograph Hereinafter, a flow cell for a chromatography detector and a chromatography detector according to embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a chromatograph including a chromatography detector according to one embodiment of the present invention. In this embodiment, the chromatograph 100 is a supercritical fluid chromatograph.

As shown in FIG. 1, the chromatograph 100 includes a chromatography detector 10 (hereinafter abbreviated as the detector 10), a bottle 20, a mobile phase supply unit 30, a sample supply unit 40, a separation column 50, and a back pressure adjustment device. 60 and a control unit 70 . The bottle 20 stores, for example, liquefied carbon dioxide cooled to about 5° C. as a mobile phase. The mobile phase supply unit 30 is, for example, a liquid transfer pump, and pressure-feeds the mobile phase stored in the bottle 20 .

The sample supply unit 40 is, for example, an injector, and introduces the sample to be analyzed into the separation column 50 together with the mobile phase supplied by the mobile phase supply unit 30 . The separation column 50 is housed inside a column constant temperature bath (not shown) and heated to a predetermined temperature (approximately 40° C. in this example) so that the introduced mobile phase is in a supercritical state. The separation column 50 separates the introduced sample into components based on differences in chemical properties or composition. The detector 10 is an absorbance detector and detects the components of the sample separated by the separation column 50 . Details of the detector 10 will be described later.

The back pressure adjusting device 60 maintains the pressure of the mobile phase channel at a critical pressure of the mobile phase or higher (for example, 8 MPa) so that the mobile phase is in a supercritical state at least in the separation column 50 . The control unit 70 includes a CPU (Central Processing Unit) and memory, or a microcomputer, etc., and includes the detector 10, the mobile phase supply unit 30, the sample supply unit 40, the separation column 50 (column constant temperature bath), and the back pressure adjustment device. 60 controls the operation of each. Further, based on the detection result by the detector 10, the control unit 70 generates a chromatogram showing, for example, the relationship between the retention time of each component and the detected intensity.

FIG. 2 is a schematic diagram showing the configuration of the detector 10 of FIG. As shown in FIG. 2 , the detector 10 includes a chromatography detector flow cell 1 (hereinafter abbreviated as flow cell 1 ), a light projecting section 11 , a condenser lens 12 , a spectroscopic section 13 and a light receiving section 14 . Flow cell 1 includes body 2 and capillary 3 .

The body portion 2 has an internal space 2C extending in one direction. Further, the body portion 2 has a light introducing portion 2A and a light leading portion 2B at one end and the other end of the internal space 2C, respectively. The light introducing portion 2A can introduce light into the internal space 2C, and the light leading portion 2B can lead light out of the internal space 2C. Further, the body portion 2 is formed with an inlet 2a and an outlet 2b that are connected to the internal space 2C. The capillary 3 has a flow path 3a inside and is housed in the internal space 2C of the main body 2 so as to extend in one direction.

A mobile phase containing a sample that has passed through the separation column 50 in FIG. Thereafter, the mobile phase flows in one direction through the channel 3a inside the capillary 3, as indicated by an arrow B. After that, the mobile phase is led out of the main body 2 through the outlet 2b as indicated by an arrow C. The above one direction is hereinafter referred to as the flow direction. In addition, the direction in which the mobile phase flows in the direction of the flow path is defined as downstream, and the opposite direction is defined as upstream. Details of the flow cell 1 will be described later.

The light projecting unit 11 is a light source that emits broadband light, and includes a deuterium lamp that emits ultraviolet light in this example. The light projecting unit 11 may include other light sources such as a tungsten lamp or an LED (light emitting diode), or may include a plurality of light sources that emit light of different wavelengths. The condenser lens 12 collects the light emitted by the light projection part 11, and irradiates the sample in the mobile phase flowing through the flow channel 3a of the flow cell 1 through the light introduction part 2A.

The light with which the sample is irradiated enters the spectroscopic unit 13 through the light lead-out unit 2B after interacting with the sample by passing through the sample. The spectroscopic section 13 is, for example, a reflective diffraction grating, and spectroscopically reflects incident light at different angles for each wavelength. The light receiving unit 14 is, for example, a photodiode array in which a plurality of photodiodes are arranged one-dimensionally. The light-receiving unit 14 receives light of each wavelength separated by the spectroscopic unit 13, and outputs a signal indicating the amount of received light to the control unit 70 in FIG. 1 as a detection result.

(2) Structure of Flow Cell FIG. 3 is a schematic partial cross-sectional view showing the structure of the flow cell 1 of FIG. Although FIG. 3 shows the structure of the upstream end of the flow cell 1, the structure of the downstream end of the flow cell 1 is similar to the structure of the upstream end. As shown in FIG. 3, the flow cell 1 includes a main body 2, a capillary 3, a pair of seal members 4 and a pair of window members 5. As shown in FIG. FIG. 3 shows one sealing member 4 and one window member 5 upstream of the flow cell 1, and omits illustration of the other sealing member 4 and the other window member 5 downstream.

The main body 2 is made of stainless steel, for example, and has a cylindrical outer shape extending in the direction of the flow path. Therefore, both ends of the body portion 2 are open. An opening at the upstream end of the main body 2 serves as a light introducing portion 2A. Also, the opening at the downstream end of the main body 2 serves as a light lead-out portion 2B (FIG. 2).

The capillary 3 is made of a material having a transmittance of 70% or more for light of any wavelength from 160 nm to 1000 nm and any refractive index. The capillary 3 may be made of a material that additionally has high chemical resistance, and is made of quartz in this example. The capillary 3 has a cylindrical outer shape extending in the direction of the flow path, and is housed in the internal space 2C of the body portion 2 . The inside of the capillary 3 becomes the channel 3a.

Further upstream of the upstream end of the capillary 3, the main body 2 is formed with an introduction port 2a penetrating from the outer peripheral surface to the inner peripheral surface. Further downstream of the downstream end of the capillary 3, the main body 2 is formed with an outlet port 2b (FIG. 2) penetrating from the outer peripheral surface to the inner peripheral surface.

Each seal member 4 is an annular member having chemical resistance. One sealing member 4 is arranged upstream of the flow cell 1 between the inner peripheral surface of the main body 2 and the outer peripheral surface of the capillary 3 . The other sealing member 4 ( FIG. 2 ) is arranged downstream of the flow cell 1 between the inner peripheral surface of the main body 2 and the outer peripheral surface of the capillary 3 . As a result, the gap between the inner peripheral surface of the main body 2 and the outer peripheral surface of the capillary 3 is sealed upstream and downstream of the flow cell 1 . Therefore, the periphery of the capillary 3 is covered with air.

Each window member 5 is made of quartz, for example. One window member 5 is attached to the light introducing portion 2</b>A at the upstream end of the main body 2 . The other window member 5 (FIG. 2) is attached to the light lead-out portion 2B (FIG. 2) at the downstream end of the body portion 2. As shown in FIG. As a result, the upstream end and the downstream end of the main body 2 are blocked so as to transmit light.

The mobile phase containing the sample that has passed through the separation column 50 (FIG. 1) is introduced into the internal space 2C of the main body 2 from the inlet 2a on the upstream side of the main body 2, and then flows from the upstream end of the capillary 3 into the channel 3a. introduced within. The mobile phase flows downstream through the channel 3 a and is discharged from the downstream end of the capillary 3 , and then discharged to the outside of the main body 2 from the outlet 2 b downstream of the main body 2 .

Also, light is emitted from the light projecting portion 11 ( FIG. 2 ) and guided to the internal space 2</b>C of the main body portion 2 through one of the window members 5 . The light guided into the internal space 2C enters the channel 3a of the capillary 3. As shown in FIG. Here, the periphery of the capillary 3 is covered with air having a smaller refractive index than the material forming the capillary 3 (quartz in this example). Therefore, the light incident on the channel 3a propagates in the direction of the channel while repeating total reflection on the outer wall surface of the capillary 3, as indicated by the dotted arrow in FIG.

By propagating through the capillary 3, the light interacts with the sample in the mobile phase within the channel 3a. The light interacting with the sample passes through the other window member 5 and is guided out of the main body 2, and after being dispersed by the spectroscopic section 13 (FIG. 2), is received by the light receiving section 14 (FIG. 2). A chromatogram is generated by the controller 70 ( FIG. 1 ) based on the absorbance calculated from the amount of light received by the light receiver 14 .

(3) Dimensional Limitation of Capillary FIG. 4 is a cross-sectional view of the capillary 3 in FIG. 3 taken along the line AA. As shown in FIG. 3, the inner diameter of the capillary 3 (the radius of the channel 3a) is r [m], and the wall surface 3b of the capillary 3 has a thickness of t [m]. Therefore, the outer diameter R [m] of the capillary 3 is (r+t). Here, the internal space 2C of the flow cell 1 in FIG. 3 is maintained at a high pressure of 8 MPa or higher. Therefore, the thickness t of the wall surface 3b of the capillary 3 has a value such that the capillary 3 does not deform even when a pressure of at least 8 MPa is applied.

Specifically, when the ratio of the outer diameter R to the inner diameter r is 1.5 or less, the lower limit of the thickness t of the wall surface 3b of the capillary 3 is restricted by the following formula (1). On the other hand, when the ratio of the outer diameter R to the inner diameter r exceeds 1.5, the lower limit of the thickness t of the wall surface 3b of the capillary 3 is restricted by the following formula (2). Here, P is the pressure resistance [MPa] of the capillary 3 and σ is the allowable tensile stress [MPa] of the material forming the capillary 3 .

However, if the thickness t of the wall surface 3b of the capillary 3 is excessively increased, the amount of light transmitted through the wall surface 3b, that is, the amount of light that does not contribute to the analysis increases, thereby reducing the accuracy of quantitative analysis. Therefore, when the capillary 3 is made of quartz, the upper limit of the thickness t of the wall surface 3b of the capillary 3 is restricted so as to satisfy the area ratio of the following formula (3). Here, S is a circular area [m ² ] surrounded by the outer edge of the wall surface 3 b in the vertical cross section of the capillary 3 . s is the area [m ² ] of the ring between the inner edge and the outer edge of the wall surface 3b in the vertical cross section of the capillary 3;

When the capillary 3 is made of any translucent material, the area ratio of formula (3) is transformed into the area ratio of formula (4) below. where n _q (λ,T) is the refractive index of quartz and is a function of wavelength λ [nm] and temperature T [K]. _nm (λ,T) is the refractive index of any translucent material forming the capillary 3 and is a function of wavelength λ[nm] and temperature T[K].

(4) Effect In the flow cell 1 according to the present embodiment, the annular capillary 3 is housed in the internal space 2C extending in the flow direction in the main body 2 so as to extend in the flow direction. A mobile phase containing a sample flows through a channel 3 a formed in the capillary 3 . A wall surface 3b of the capillary 3 has a thickness that does not deform under a pressure of 8 MPa.

Here, a first value and a second value are defined. The first value is a value that depends on the area of the region surrounded by the outer edge of the wall surface 3b in a cross section that intersects the direction of the flow path. The second value is a value that depends on the area of the region between the outer edge and the inner edge of the wall surface 3b in the above cross section. The upper limit of the thickness of the wall surface 3b is restricted so that the ratio of the second value to the first value is 0.8 or less.

According to this limitation, even if the thickness of the wall surface 3b is increased so that the capillary 3 is not deformed under a pressure of 8 MPa, an increase in the amount of light transmitted through the wall surface 3b is suppressed. This allows the flow cell 1 to be used for highly accurate analysis.

Further, even when the internal space 2C of the main body 2 is pressurized so that the mobile phase becomes supercritical in the flow path 3a, the capillary 3 does not deform. Therefore, the sample can be analyzed at high speed by using the supercritical fluid as the mobile phase.

(5) Other Embodiments In the above embodiment, the flow cell 1 is provided in the detector 10 of the supercritical fluid chromatograph, but the embodiment is not limited to this. The flow cell 1 may be provided in a liquid chromatograph detector 10 .

In the above embodiment, the flow cell 1 is an external reflection type light guide cell that mainly reflects light on the outer wall surface of the capillary 3, but the embodiment is not limited to this. The flow cell 1 may be an internal reflection type light guide cell in which light is mainly reflected by the inner wall surface of the capillary 3 .

(6) Examples and Comparative Examples In the following Examples 1, 2 and Comparative Example 1, three types of flow cells made of quartz and having different capillary dimensions were prepared. FIG. 5 is a diagram showing the dimensions of capillaries in Example 1, Example 2, and Comparative Example 1. FIG.

As shown in FIG. 5, the capillary of Example 1 had an inner diameter r of 180 μm, a wall thickness t of 70 μm, and an area ratio s/S of 0.4816. In the capillary of Example 2, the inner diameter r was 180 μm, the wall thickness t was 155 μm, and the area ratio s/S was 0.7113. In the capillary of Comparative Example 1, the inner diameter r was 180 μm, the wall thickness t was 320 μm, and the area ratio s/S was 0.8704.

Using each of the flow cells of Example 1, Example 2, and Comparative Example 1, the linearity between the concentration and absorbance of a known sample was measured three times. Also, the relationship between the area ratio of each flow cell and the measured linearity error was evaluated. FIG. 6 is a diagram showing the relationship between the flow cell area ratio and the measured linearity error.

As shown in FIG. 6, in the flow cells of Examples 1 and 2, the linearity error was 20% or less even when the error bars were considered. On the other hand, in the flow cell of Comparative Example 1, the linearity error was greater than 20% when considering the error bars. From the results of comparison between Examples 1 and 2 and Comparative Example 1, when the capillary is made of quartz, the linearity error is suppressed to 20% or less by setting the area ratio s/S to 0.8 or less. , it was confirmed that it is possible to perform quantitative analysis with sufficient accuracy.

Next, in Example 4, the flow cell of Example 2 was used to measure the baseline of the chromatogram. In the measurement, the mobile phase was liquefied carbon dioxide, and the flow rate of the mobile phase was 2 mL/min. Also, the temperature of the head of the back pressure adjusting device was adjusted to 50° C., and the pressure of the back pressure adjusting device was sequentially changed to 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa and 15 MPa.

In Comparative Example 2, the same measurement as in Example 4 was performed using a general liquid chromatograph flow cell that does not include a capillary. 7 is a diagram showing the baseline of the chromatogram in Example 4. FIG. 8 is a diagram showing the baseline of the chromatogram in Comparative Example 2. FIG.

As shown in FIG. 7, in Example 4, no large noise occurred in the baseline. In addition, the baseline variation was relatively small when the pressure of the back pressure regulator was varied from 10 MPa to 15 MPa. On the other hand, as shown in FIG. 8, in Comparative Example 2, large noise occurred in the baseline. In addition, the baseline variation when the pressure of the back pressure regulator was varied from 10 MPa to 15 MPa was greater than that in Example 4.

Thus, it was confirmed that by using the flow cell of Example 2, it is possible to reduce baseline noise even in supercritical chromatography. It was also confirmed that baseline fluctuations due to the refractive index effect can be reduced.

(7) Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects.

(Section 1) A flow cell for a chromatography detector according to one aspect,
A chromatographic detector flow cell used to generate a chromatogram of a sample, comprising:
a main body having an inner space extending in one direction;
an annular capillary that is housed in the internal space of the main body so as to extend in the one direction and forms a flow path through which a mobile phase containing a sample flows;
the capillary comprises a wall having a thickness that does not deform under a pressure of 8 MPa;
a first value dependent on the area of the region enclosed by the outer edge of the wall surface in the cross section intersecting one direction;
a second value dependent on the area of the region between the outer edge and the inner edge of the wall surface in the cross section;
The upper limit of the wall thickness may be restricted such that the ratio of the second value to the first value is 0.8 or less.

In this flow cell for a chromatography detector, an annular capillary is housed so as to extend in one direction in the inner space extending in one direction in the main body. A mobile phase containing a sample flows through a channel formed in the capillary. The capillary wall has a thickness that does not deform under a pressure of 8 MPa.

Here, a first value and a second value are defined. The first value is a value that depends on the area of the area enclosed by the outer edge of the wall in a cross-section. The second value is a value that depends on the area of the region between the outer edge and the inner edge of the wall in said cross section. The upper wall thickness is limited such that the ratio of the second value to the first value is 0.8 or less.

According to this limitation, even if the wall thickness is increased so that the capillary is not deformed under a pressure of 8 MPa, an increase in the amount of light transmitted through the wall is suppressed. This allows the flow cell for chromatography detectors to be used for highly accurate analysis.

(Section 2) In the flow cell for a chromatography detector according to Section 1,
the ratio of the outer diameter to the inner diameter of the capillary is 1.5 or less;
When the pressure resistance of the capillary is P [MPa] and the allowable tensile stress of the material forming the capillary is σ [MPa], the lower limit of the wall thickness t [m] is defined by the following equation (1). may

According to this configuration, even when a high pressure is applied to a capillary having an outer diameter to inner diameter ratio of 1.5 or less, the capillary is prevented from being deformed.

(Section 3) In the flow cell for a chromatography detector according to Section 1,
the ratio of the outer diameter to the inner diameter of the capillary is greater than 1.5;
Assuming that the withstand voltage of the capillary is P [MPa] and the allowable tensile stress of the material forming the capillary is σ [MPa], the lower limit of the wall thickness t [m] is defined by the following equation (2). may

According to this configuration, even when a high pressure is applied to a capillary having an outer diameter to inner diameter ratio of greater than 1.5, the capillary is prevented from being deformed.

(Section 4) In the flow cell for a chromatography detector according to any one of Sections 1 to 3,
The capillary is made of quartz,
When the inner diameter of the capillary is r [m], the upper limit of the thickness t [m] of the wall surface may be restricted so as to satisfy the following formula (3).

In this case, a capillary that can be used for highly accurate analysis can be easily formed from quartz.

(Section 5) In the flow cell for a chromatography detector according to any one of Sections 1 to 3,
The capillary is formed of any translucent material,
Assuming that the refractive index of the arbitrary material is _nm , the refractive index of quartz is _nq , and the inner diameter of the capillary is r [m], the upper limit of the wall thickness t [m] is given by the following formula (4 ) may be restricted to satisfy

In this case, the capillary that can be used for highly accurate analysis can be made of any translucent material.

(Section 6) In the flow cell for a chromatography detector according to any one of Sections 1 to 3,
The mobile phase is a supercritical fluid,
The internal space of the main body may be pressurized so that the mobile phase is in a supercritical state within the channel.

According to this configuration, the capillary does not deform even when the internal space of the main body is pressurized so that the mobile phase becomes supercritical in the channel. Therefore, the sample can be analyzed at high speed by using the supercritical fluid as the mobile phase.

(Section 7) A chromatography detector according to another aspect,
A flow cell for a chromatography detector according to any one of items 1 to 3;
a light projecting unit that emits light to the mobile phase containing the sample flowing through the channel of the flow cell for chromatography detector;
A light-receiving part may be provided which receives the light emitted by the light-projecting part and transmitted through the sample, and outputs a signal indicating the amount of light received.

In this chromatography detector, light is emitted from the light projecting section to the mobile phase containing the sample flowing through the channel of the flow cell for the chromatography detector. The light emitted by the light-projecting part and transmitted through the sample is received by the light-receiving part, and a signal indicating the amount of light received is output.

In the flow cell for chromatography detector, even when the wall thickness is increased so that the capillary does not deform under a pressure of 8 MPa, an increase in the amount of light transmitted through the wall is suppressed. This allows the chromatographic detector to be used for high precision analysis.

Claims (7)

A chromatographic detector flow cell used to generate a chromatogram of a sample, comprising:
a main body having an inner space extending in one direction;
an annular capillary that is housed in the internal space of the main body so as to extend in the one direction and forms a flow path through which a mobile phase containing a sample flows;
the capillary comprises a wall having a thickness that does not deform under a pressure of 8 MPa;
a first value that is the area of the region surrounded by the outer edge of the wall surface in the cross section that intersects the one direction;
defining a second value that is the area of the region between the outer edge and the inner edge of the wall surface in the cross-section;
A flow cell for a chromatography detector, wherein the upper limit of the wall thickness is restricted such that the ratio of the second value to the first value is 0.8 or less. the ratio of the outer diameter to the inner diameter of the capillary is 1.5 or less;
When the pressure resistance of the capillary is P [MPa], the inner diameter of the capillary is r [m], and the allowable tensile stress of the material forming the capillary is σ [MPa], the thickness t [m] of the wall surface is 2. The flow cell for chromatography detector according to claim 1, wherein the lower limit is restricted by the following formula (1).

the ratio of the outer diameter to the inner diameter of the capillary is greater than 1.5;
When the pressure resistance of the capillary is P [MPa], the inner diameter of the capillary is r [m], and the allowable tensile stress of the material forming the capillary is σ [MPa], the thickness t [m] of the wall surface is 2. The flow cell for chromatography detector according to claim 1, wherein the lower limit is restricted by the following formula (2).

The capillary is made of quartz,
The upper limit of the thickness t [m] of the wall surface is limited so as to satisfy the following formula (3) when the inner diameter of the capillary is r [m]. flow cell for chromatographic detectors.

The capillary is formed of any translucent material,
Assuming that the refractive index of the arbitrary material is _nm , the refractive index of quartz is _nq , and the inner diameter of the capillary is r [m], the upper limit of the wall thickness t [m] is given by the following formula (4 ), the flow cell for a chromatography detector according to any one of claims 1 to 3.

The mobile phase is a supercritical fluid,
The flow cell for a chromatography detector according to any one of claims 1 to 3, wherein the internal space of said main body is pressurized so that said mobile phase is in a supercritical state within said channel. A flow cell for a chromatography detector according to any one of claims 1 to 3;
a light projecting unit that emits light to the mobile phase containing the sample flowing through the channel of the flow cell for chromatography detector;
A chromatography detector, comprising: a light-receiving section that receives the light emitted by the light-projecting section and transmitted through the sample, and outputs a signal indicating the amount of received light.

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