Concentration measuring device and concentration measuring method

Abstract

The length of the optical path through which the first light passes in the liquid and the length of the optical path through which the second light passes in the liquid are made close to each other, thereby increasing the accuracy of measuring the concentration of the sample. [Solution] The concentration measuring device 1 includes a well 2, a light irradiator 4, a light detector 5, and a processor 6. The well 2 has a cylindrical sidewall 21 and a bottom 22, and contains a liquid 3, in which a sample is dissolved or suspended in water, in an internal region 24 formed by the sidewall 21 and the bottom 22. The light irradiator 4 irradiates the liquid 3 with a first light P1 having a first wavelength and a second light P2 having a second wavelength so that the light passes through both the bottom 22 of the well 2 and the liquid surface 3a of the liquid 3. The light detector 5 detects the light intensities of the first light P1 and the second light P2 that have passed through the center of the internal region 24 or a position separated from the center of the internal region 24 by a distance equal to or less than ¼ of the inner diameter of the sidewall 21, as viewed from a first direction B1.

Description

[Technical Field]

[0001] The present disclosure relates to a concentration measurement device and a concentration measurement method. [Background technology]

[0002] Patent Document 1 discloses a measurement method for determining the optical path length of a sample contained in a well and containing a solvent and an analyte dissolved or suspended in the solvent. This method involves measuring a first optical signal resulting from the transmission of light at a first wavelength perpendicularly through the sample, and measuring a second optical signal resulting from the transmission of light at a second wavelength perpendicularly through the sample. The wavelengths of the first and second light are in the near-infrared region of 750 nm to 2500 nm. The optical path length of the sample is then determined based on a predetermined relationship between both the first and second optical signals and the optical path length of the solvent. Furthermore, a third optical signal resulting from the transmission of light at a third wavelength through the sample is measured, and the first, second, and third optical signals are related to each other. This allows the proportion of light at the third wavelength transmitted by the analyte, or the absorbance of the analyte at the third wavelength, to be determined relative to the optical absorption path length of the analyte. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 6,404,501 Summary of the Invention [Problem to be solved by the invention]

[0004] The concentration of a sample in a liquid in which the sample is dissolved or suspended in water can be measured, for example, by the following method. First, the liquid is placed in a well. A first light having a wavelength that is less absorbed by the sample and more absorbed by water is passed through the liquid, and the intensity of the first light after passing through is detected. A second light having a wavelength that is more absorbed by the sample and less absorbed by water is passed through the liquid, and the intensity of the second light after passing through is detected. Then, the optical path length is calculated based on the absorbance calculated from the intensity of the first light after passing through, and the concentration of the sample is calculated based on that optical path length and the absorbance calculated from the intensity of the second light after passing through.

[0005] The above method assumes that the length of the optical path through which the first light passes in the liquid is equal to the length of the optical path through which the second light passes in the liquid. Therefore, if these lengths differ, the accuracy of measuring the sample concentration decreases. However, depending on the positions at which the first light and the second light pass through the liquid, it may be difficult to make these lengths equal. The present disclosure aims to provide a concentration measurement device and a concentration measurement method that can increase the accuracy of measuring the sample concentration by making the optical path length through which the first light passes and the optical path length through which the second light passes closer to each other. [Means for solving the problem]

[0006] [1] A concentration measurement device according to the present disclosure includes a well, a light irradiator, a light detector, and a calculation unit. The well has a cylindrical sidewall extending along a first direction and a bottom closing one end of the cylindrical sidewall. A liquid containing a sample dissolved or suspended in water is contained in an internal region formed by the sidewall and the bottom. The light irradiator irradiates the liquid with first light having a first wavelength and second light having a second wavelength so that the light passes through both the bottom of the well and the liquid surface. The light detector detects the intensities of the first light and second light that have passed through the liquid. The calculation unit calculates the concentration of the sample in the liquid based on the optical path length of the first light in the liquid calculated based on the first absorbance, which is the liquid's absorbance of the first light, and the second absorbance, which is the liquid's absorbance of the second light. A concentration measurement method according to the present disclosure also includes a containing step, a light detection step, and a calculation step. In the containing step, a liquid in which a sample is dissolved or suspended in water is contained in an internal region formed by the sidewall and the bottom of a well having a cylindrical sidewall extending along a first direction and a bottom closing one end of the cylindrical sidewall. In the light detection step, a first light having a first wavelength and a second light having a second wavelength are irradiated onto the liquid so that the first light passes through both the bottom of the well and the liquid surface, and the intensities of the first light and the second light passing through the liquid are detected. In the calculation step, the concentration of the sample in the liquid is calculated based on the optical path length of the first light in the liquid calculated based on the first absorbance, which is the liquid's absorbance of the first light, and the second absorbance, which is the liquid's absorbance of the second light. In these concentration measurement devices and concentration measurement methods, the absorbance of the sample at the first wavelength is 0.005 or less, and the absorbance of water at the first wavelength is 0.2 or more. The absorbance of the sample at the second wavelength is 0.05 or more, and the absorbance of water at the second wavelength is 0.005 or less. The light detection unit (or in the light detection step) detects the light intensity of the first light and the second light that pass through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 4 or less of the inner diameter of the side wall when viewed from the first direction.

[0007] The liquid surface of the liquid contained in the well is not flat but has a meniscus due to surface tension and other factors. Typically, the liquid surface height is highest at the periphery of the liquid surface and decreases toward the center. The rate of change in the liquid surface height in the radial direction of the well is greatest at the periphery and decreases toward the center. In other words, the liquid surface height is more stable as it approaches the center. In the concentration measurement device and concentration measurement method described above in [1], the light detection unit (or the light detection step) detects the intensities of the first and second lights that have passed through the center of the internal region or a position separated from the center of the internal region by a distance of ¼ or less of the inner diameter of the sidewall, as viewed from the first direction. In this way, by detecting the intensities of the first and second lights that have passed near the center of the liquid surface, the influence of the meniscus is reduced, and the optical path lengths of the first and second lights in the liquid passing through the liquid can be made closer to each other. This improves the accuracy of measuring the sample concentration. Additionally, in the concentration measurement device and method of [1] above, the absorbance of the sample at the first wavelength is 0.005 or less, the absorbance of water at the first wavelength is 0.2 or more, the absorbance of the sample at the second wavelength is 0.05 or more, and the absorbance of water at the second wavelength is 0.005 or less. In this way, the absorption of water for the first light is significantly greater than the absorption of the sample for the first light, and the absorption of the sample for the second light is significantly greater than the absorption of water for the second light, thereby further improving the accuracy of measuring the sample concentration.

[0008] [2] In the concentration measurement device and concentration measurement method described in [1] above, the absorbance of water at the first wavelength may be 2.0 or less, and the absorbance of the sample at the second wavelength may be 1.5 or less. In this way, the absorbance of water to the first light and the absorbance of the sample to the second light are not too large, thereby reducing noise due to the influence of stray light and further improving the measurement accuracy of the sample concentration.

[0009] [3] In the concentration measurement device and concentration measurement method of [1] and [2] above, the absorbance of water at the first wavelength may be 0.5 or more and 1.0 or less. In this case, the difference between the absorption of the first light by water and the absorption of the first light by the sample is further increased, and noise due to the influence of stray light can be further reduced, thereby further improving the measurement accuracy of the sample concentration.

[0010] [4] In the concentration measurement device and concentration measurement method according to [1] to [3] above, the absorbance of the sample at the first wavelength may be 0.002 or less. In this case, the difference between the absorption of the first light by water and the absorption of the first light by the sample becomes even greater, thereby further improving the accuracy of measuring the sample concentration.

[0011] [5] In the concentration measurement device and concentration measurement method described in [1] to [4] above, the absorbance of the sample at the second wavelength may be 0.3 or more and 1.0 or less. In this case, the difference between the absorption of the second light by the sample and the absorption of the second light by water becomes larger, and noise due to the influence of stray light can be further reduced, thereby further improving the measurement accuracy of the sample concentration.

[0012] [6] In the concentration measurement device and concentration measurement method according to [1] to [5] above, the absorbance of water at the second wavelength may be 0.002 or less. In this case, the difference between the absorption of the second light by the sample and the absorption of the second light by water becomes even greater, thereby further improving the accuracy of measuring the sample concentration.

[0013] [7] In the concentration measurement device and concentration measurement method described in [1] to [6] above, the inner diameter of the cylindrical side wall may be 10 mm or less. When using a well with such a small inner diameter, the influence of the meniscus becomes large and the optical path length is likely to vary, so the concentration measurement device and concentration measurement method described in [1] to [6] above are effective.

[0014] [8] The concentration measuring device according to any one of [1] to [7] above may include a well plate in which the well and another well having the same structure as the well are arranged side by side. The light irradiating unit may irradiate both the first light and the second light onto the liquid in the well and the liquid in the other well, respectively. The light detecting unit may detect the light intensity of the first light and the second light passing through the liquid in the well, and the light intensity of the first light and the second light passing through the liquid in the other well. The calculating unit may calculate the concentration of the sample in the well and the concentration of the sample in the other well. In this case, the sample concentrations of multiple liquids can be measured simultaneously, improving the efficiency of the measurement operation. In addition, measurement errors due to differences in optical path lengths between multiple wells can be reduced.

[0015] [9] In the concentration measurement device according to any one of [1] to [8] above, the light irradiation unit may include a single light source that outputs both the first light and the second light. Similarly, in the light detection step of the concentration measurement method according to any one of [1] to [8] above, a single light source that outputs both the first light and the second light may be used. In this case, the number of light sources can be reduced, simplifying the device configuration. In addition, since the passage position of the first light and the passage position of the second light coincide with or are close to each other, the measurement accuracy can be further improved.

[0016]

[10] In the concentration measurement device according to any one of the above items [1] to [8], the light irradiating unit may include a first light source that outputs the first light and a second light source that is provided separately from the first light source and that outputs the second light. Similarly, in the light detection step of the concentration measurement method according to any one of the above items [1] to [8], the first light source that outputs the first light and the second light source that is provided separately from the first light source and that outputs the second light may be used. In this case, the wavelengths of the first light source and the second light source can be set individually, thereby increasing the degree of freedom in wavelength selection of the first wavelength and the second wavelength.

[0017]

[11] In the concentration measurement device according to any one of [1] to

[10] above, the light detection unit may include a single light detection element that detects the light intensities of both the first light and the second light. Similarly, in the light detection step of the concentration measurement method according to any one of [1] to

[10] above, a single light detection element that detects the light intensities of both the first light and the second light may be used. In this case, the number of light detection elements can be reduced, simplifying the device configuration. In addition, it is easy to make the passage position of the first light and the passage position of the second light coincide with or close to each other, further improving measurement accuracy.

[0018]

[12] In the concentration measuring device according to any one of [1] to

[10] above, the light detecting unit may include a first light detecting element that detects the light intensity of the first light and a second light detecting element that detects the light intensity of the second light. Similarly, in the light detecting step of the concentration measuring method according to any one of [1] to

[10] above, a first light detecting element that detects the light intensity of the first light and a second light detecting element that detects the light intensity of the second light may be used. In this case, the wavelength sensitivity characteristics of the first light detecting element and the second light detecting element can be set individually, thereby increasing the degree of freedom in wavelength selection of the first wavelength and the second wavelength.

[0019]

[13] In the concentration measurement device and concentration measurement method described in [1] to

[12] above, when a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as the first spot and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as the second spot, the overlapping area of ​​the first spot and the second spot as viewed from the first direction may be 35% or more of the area of ​​the first spot and 35% or more of the area of ​​the second spot. In this case, by detecting the first absorbance and the second absorbance in the overlapping portion of the first spot and the second spot, it is possible to reduce measurement errors in the optical path length caused by the separation between the optical axes of the first light and the second light. This can further improve the measurement accuracy of the sample concentration.

[0020]

[14] In the concentration measurement device according to any one of [1] to

[13] above, the light detection unit may detect the light intensity of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 6 or less of the inner diameter of the sidewall, as viewed from the first direction. Similarly, in the light detection step of the concentration measurement method according to any one of [1] to

[13] above, the light intensity of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 6 or less of the inner diameter of the sidewall, as viewed from the first direction, may be detected. In this case, the optical paths of the detected first and second lights are closer to the center of the liquid surface, further reducing the influence of the meniscus and enabling the optical path lengths of the first light and the second light to be closer to each other. This further improves the accuracy of measuring the sample concentration.

[0021]

[15] In the concentration measurement device and concentration measurement method according to [1] to

[14] above, when a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, the diameters of the first spot and the second spot may be one-third or less of the inner diameter of the cylindrical side wall. Since the diameters of the first spot and the second spot are not too large, the influence of stray light can be reduced and the measurement accuracy of the sample concentration can be further improved.

[0022]

[16] In the concentration measurement device and concentration measurement method described above in

[15] , the diameter of the first spot and the second spot may be 2 mm or less. [Effects of the Invention]

[0023] According to the present disclosure, a concentration measurement device and a concentration measurement method can be provided that can improve the accuracy of measuring sample concentration by making the length of the optical path in the liquid through which the first light passes closer to the length of the optical path in the liquid through which the second light passes. [Brief explanation of the drawings]

[0024] [Figure 1]FIG. 1 is a diagram schematically illustrating the configuration of a concentration measuring device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a graph showing the relationship between both the first wavelength and the second wavelength and the absorption spectra of water and the sample. [Figure 3] FIG. 3 is a view of the well as seen from a first direction. [Figure 4] FIG. 4 is a diagram showing various configuration examples of the light irradiation unit. [Figure 5] FIG. 5 is a diagram showing various configuration examples of the light irradiation unit. [Figure 6] FIG. 6 shows various configuration examples of the light detection unit. [Figure 7] FIG. 7 shows various configuration examples of the light detection unit. [Figure 8] FIG. 8 is a diagram showing various configuration examples of the light detection unit. [Figure 9] FIG. 9 is a flowchart showing a concentration measurement method according to the embodiment. [Figure 10] FIG. 10 is a diagram schematically showing the configuration of a concentration measuring device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0025] Specific examples of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicate explanations will be omitted.

[0026] 1 is a diagram schematically illustrating the configuration of a concentration measurement device 1 according to an embodiment of the present disclosure. As shown in FIG. 1, the concentration measurement device 1 includes a well 2, a light irradiation unit 4, a light detection unit 5, and a calculation unit 6.

[0027] The well 2 is a hollow container having a sidewall 21 and a bottom 22. The well 2 has an interior region 24 formed by the sidewall 21 and the bottom 22. The sidewall 21 has a tubular shape extending along the first direction B1, and in one example, has a cylindrical shape. The upper end of the tubular sidewall 21 is open. The bottom 22 has a plate shape that intersects (e.g., is perpendicular to) the first direction B1 and closes the lower end of the tubular sidewall 21. The well 2 contains a liquid 3 in the interior region 24. The liquid 3 is placed in the well 2 for each measurement by the user of the concentration measuring device 1. The liquid 3 is a sample dissolved or suspended in water. The sample is added for the purpose of quantifying, for example, protein, and causes a color reaction by chemical reaction or complex formation with the protein. The sample is, for example, a triphenylmethane dye such as CBB G-250, a water-soluble tetrazolium salt such as WST-8, or a Folin-Ciocalteu reagent. The liquid 3 has a liquid surface 3a. The liquid surface 3a is curved concavely due to the surface tension of the liquid 3, etc. The height of the liquid surface 3a from the bottom 22 is highest at the periphery of the liquid surface 3a and lowest at the center of the liquid surface 3a (in other words, at the center of the cylindrical side wall 21).

[0028] The light irradiation unit 4 is disposed outside the well 2 and irradiates the liquid 3 with the first light P1 and the second light P2. The light irradiation unit 4 irradiates the liquid 3 with the first light P1 and the second light P2 so that the first light P1 and the second light P2 pass through both the bottom 22 and the liquid surface 3a. In the illustrated example, the light irradiation unit 4 is disposed on the lower end side (bottom 22 side) of the well 2, but the light irradiation unit 4 may also be disposed on the upper end side of the well 2. The optical axes of the first light P1 and the second light P2 may be parallel to the first direction B1 or may be inclined with respect to the first direction B1. The optical axis of the second light P2 is parallel to the optical axis of the first light P1. The optical axis of the second light P2 may coincide with the optical axis of the first light P1 or may be separated from the optical axis of the first light P1. The light irradiation unit 4 may have, for example, a semiconductor laser element, and the first light P1 and the second light P2 may be, for example, laser light. Alternatively, the light irradiation unit 4 may include, for example, a surface-emitting LED and an optical system that collimates the light from the surface-emitting LED. Alternatively, the light irradiation unit 4 may include, for example, a white light source and a spectroscope that separates the white light from the white light source.

[0029] The first light P1 has a first wavelength λ1 as its center wavelength. The first wavelength λ1 is in a wavelength range where the absorbance with respect to water is 0.2 to 2 (equivalent to a wavelength range where the molar absorption coefficient with respect to water is 0.4 [L / mol cm] to 4 [L / mol cm]), for example, 930 nm to 1100 nm or 1150 nm to 1380 nm. Alternatively, the first wavelength λ1 may be in a wavelength range where the absorbance with respect to water is 0.5 to 1 (equivalent to a wavelength range where the molar absorption coefficient with respect to water is 1 [L / mol cm] to 2 [L / mol cm]), for example, 1150 nm to 1350 nm. When the first wavelength λ1 is within these ranges, sufficient transmitted light can be ensured even when the optical path length is long, for example, 15 mm to 20 mm. Furthermore, since the intensity of the transmitted light is expected to change by 1% or more for every 1 mm change in the optical path length, high resolution can be ensured. The wavelength width of the first light P1 is, for example, within λ1±5 nm.

[0030] The second light P2 has a second wavelength λ2, which is different from the first wavelength λ1, as its center wavelength. The second wavelength λ2 is in a wavelength range in which the absorbance of the sample is in the range of 0.05 to 1.5 (which corresponds to a molar absorption coefficient of 9×10 6 [L / mol cm] ~ 3 × 10 10 The wavelength range of the second light P2 is within the range of [L / mol cm]. Since the samples to be measured, such as pigments, often have an absorption peak in the visible range of 400 to 750 nm, a wavelength within the range of 400 to 750 nm is often used as the second wavelength λ2. The wavelength width of the second light P2 only needs to be narrower than the absorption wavelength range of the sample.

[0031] FIG. 2 is a graph showing the relationship between both the first wavelength λ1 and the second wavelength λ2 and the absorption spectra of water and the sample. In FIG. 2, the horizontal axis represents wavelength, and the vertical axis represents absorbance. Curve G1 represents the absorption spectrum of water, and curve G2 represents the absorption spectrum of the sample. As shown in FIG. 2, the first wavelength λ1 is included in the absorption wavelength range of water, but is substantially not included in the absorption wavelength range of the sample. The second wavelength λ2 is included in the absorption wavelength range of the sample, but is substantially not included in the absorption wavelength range of water.

[0032] Specifically, the absorbance of the sample at the first wavelength λ1 is 0.005 or less, 0.002 or less, or 0.001 or less. Alternatively, the molar extinction coefficient of the sample at the first wavelength λ1 is 9×10 5 [L / mol cm] or less or 1×10 6 The absorbance of water at the first wavelength λ1 is 0.2 or more or 0.5 or more, and 2.0 or less or 1.0 or less. Alternatively, the molar absorption coefficient of water at the first wavelength λ1 is 0.4 [L / mol cm] or more or 1 [L / mol cm] or more, and 4 [L / mol cm] or less or 2 [L / mol cm] or less. The absorbance of the sample at the second wavelength λ2 is 0.05 or more or 0.3 or more, and 1.5 or less or 1.0 or less. Alternatively, the molar absorption coefficient of the sample at the second wavelength λ2 is 9×10 6 [L / mol cm] or more or 6 × 10 7 [L / mol cm] or more and 3×10 10 [L / mol cm] or less or 2 × 10 10 The absorbance of water at the second wavelength λ2 is 0.005 or less, 0.002 or less, or 0.001 or less. Alternatively, the molar extinction coefficient of water at the second wavelength λ2 is 0.002 or less, or 0.001 or less.

[0033] In one example, the first wavelength λ1 is at least 300 nm or 500 nm longer than the second wavelength λ2. If the first wavelength λ1 is at least 300 nm longer than the second wavelength λ2, the absorbance of the sample at the first wavelength λ1 is low enough not to affect the optical path length measurement, and the absorbance of water at the second wavelength λ2 is low enough not to affect the concentration measurement.

[0034] FIG. 3 is a view of the well 2 as viewed from a first direction B1. In addition to the sidewall 21 of the well 2, FIG. 3 also shows a first spot P1s and a second spot P2s. The first spot P1s is defined as a region of the first light P1 having a light intensity equal to or greater than 36.8% of the light intensity at the peak position of the first light P1 (typically, the optical axis position of the first light P1). The second spot P2s is defined as a region of the second light P2 having a light intensity equal to or greater than 36.8% of the light intensity at the peak position of the second light P2 (typically, the optical axis position of the second light P2). Typically, the cross sections of the first spot P1s and the second spot P2s perpendicular to the optical axis direction are circular. The diameter D1 of the first spot P1s and the diameter D2 of the second spot P2s are equal to or less than 1 / 3 of the inner diameter L of the sidewall 21. In one example, the inner diameter L of the sidewall 21 is equal to or less than 10 mm. In one example, the diameter D1 of the first spot P1s and the diameter D2 of the second spot P2s are 2 mm or less. Furthermore, the distance E1 between the peak position of the light intensity of the first light P1 (typically the center of the first spot P1s) and the center line Q of the internal region 24 along the first direction B1 is, for example, 1 / 6 or less of the inner diameter L of the side wall 21. Similarly, the distance E2 between the peak position of the light intensity of the second light P2 (typically the center of the second spot P2s) and the center line Q of the internal region 24 is, for example, 1 / 6 or less of the inner diameter L of the side wall 21. The distance E1 and the distance E2 may be equal to or different from each other. The peak position of the light intensity of the first light P1 may coincide with the peak position of the light intensity of the second light P2.

[0035] When viewed from the first direction B1, the first spot P1s and the second spot P2s overlap each other. The area of ​​the overlap A (shown by hatching in the figure) between the first spot P1s and the second spot P2s is 35% or more of the area of ​​the first spot P1s and 35% or more of the area of ​​the second spot P2s. The overlap A includes the center line Q of the internal region 24. In one example, the center of the overlap A coincides with the center line Q of the internal region 24.

[0036] The light irradiation unit 4 may include a single light source that outputs both the first light P1 and the second light P2. Alternatively, the light irradiation unit 4 may include a first light source that outputs the first light P1 and a second light source that is provided separately from the first light source and outputs the second light P2. Figures 4 and 5 are diagrams showing various configuration examples of the light irradiation unit 4.

[0037] The light irradiation unit 4A shown in FIG. 4(a) includes a first light source 41, a second light source 42, a mirror 431, and a mirror 432. The first light source 41 outputs a first light P1 with an optical axis intersecting the direction in which the optical path of the first light P1 extends within the liquid 3. The second light source 42 outputs a second light P2 with an optical axis intersecting the direction in which the optical path of the second light P2 extends within the liquid 3. The mirror 431 is, for example, a metal mirror, a dielectric multilayer mirror, or a prism mirror that reflects almost all of the light, and reflects the first light P1 toward the liquid 3. The mirror 432 is, for example, a half mirror, a beam splitter, or a dichroic mirror, and transmits the first light P1 and reflects the second light P2 toward the liquid 3. At this time, the first light P1 and the second light P2 overlap each other. The arrangement of the first light source 41 may be interchanged with the arrangement of the second light source 42.

[0038] The light irradiation unit 4B shown in FIG. 4(b) has a first light source 41, a second light source 42, and a mirror 433. The first light source 41 is disposed adjacent to the second light source 42. The first light source 41 and the second light source 42 output the first light P1 and the second light P2 parallel to each other, with their optical axes intersecting the extension direction of the optical path of the second light P2 in the liquid 3. The mirror 433 is, for example, a metal mirror, a dielectric multilayer mirror, or a prism mirror that reflects almost all of the light, and reflects the first light P1 and the second light P2 toward the liquid 3. Note that the first light source 41 and the second light source 42 may output the first light P1 and the second light P2 toward the liquid 3. In this case, the mirror 433 need not be provided.

[0039] The light irradiation unit 4C shown in FIG. 4(c) includes a first light source 41, a second light source 42, and a lens 45. The light irradiation unit 4C further includes an optical fiber coupler 44 including optical fibers 461, 462, and 463. The first light source 41 inputs a first light P1 to one end of the optical fiber 461. The second light source 42 inputs a second light P2 to one end of the optical fiber 462. The optical fiber coupler 44 multiplexes the first light P1 propagated through the optical fiber 461 and the second light P2 propagated through the optical fiber 462, and outputs the multiplexed light from the optical fiber 463. The lens 45 collimates the multiplexed light output from the optical fiber 463.

[0040] The light irradiation unit 4D shown in FIG. 5(a) includes a light source 40, a diffraction grating 47, and an aperture 48. The light source 40 outputs a third light P3 containing both a wavelength component of a first wavelength λ1 and a wavelength component of a second wavelength λ2. The third light P3 is, for example, white light. The diffraction grating 47 separates the third light P3 into a plurality of wavelength components. At this time, the wavelength component of the first wavelength λ1, i.e., the first light P1, and the wavelength component of the second wavelength λ2, i.e., the second light P2, are emitted in different directions. The aperture 48 passes either the first light P1 or the second light P2 depending on the angle of the diffraction grating 47. After passing through the aperture 48, the first light P1 or the second light P2 enters the liquid 3.

[0041] The light irradiation unit 4E shown in FIG. 5(b) includes a first light source 41, a second light source 42, and an integrating sphere 49. The first light source 41 inputs a first light P1 into the integrating sphere 49. The second light source 42 inputs a second light P2 into the integrating sphere 49. The integrating sphere 49 scatters and combines the first light P1 and the second light P2 inside the integrating sphere 49, and outputs the combined light. Light may be guided from the first light source 41 and the second light source 42 to the integrating sphere 49 by spatial propagation or by an optical waveguide or optical fiber. Alternatively, the first light source 41 and the second light source 42 may be disposed within the integrating sphere 49. Light may also be guided from the integrating sphere 49 to the liquid 3 by spatial propagation or by an optical waveguide or optical fiber. The light emitted from the integrating sphere 49 may be collimated by a lens or the like.

[0042] Referring again to Figure 1, the light detection unit 5 detects the light intensity of the first light P1 and the second light P2 that have passed through the liquid 3. In the illustrated example, the light detection unit 5 is disposed on the upper end side of the well 2, but if the light irradiation unit 4 is disposed on the upper end side of the well 2, the light detection unit 5 may be disposed on the lower end side (bottom 22 side) of the well 2.

[0043] The light detection unit 5 detects the light intensity of the first light P1 and the second light P2 that pass through the center of the internal region 24 or a position spaced from the center of the internal region 24 by a distance equal to or less than ¼ of the inner diameter L of the sidewall 21, as viewed from the first direction B1. In one example, the light irradiator 4 causes the first light P1 and the second light P2 to pass through a region 25 that is spaced from the center line Q of the internal region 24 by a distance equal to or less than ¼ of the inner diameter L, and the light detection unit 5 detects the first light P1 and the second light P2. This configuration is employed, for example, when the light irradiator 4 includes a semiconductor laser element. In this case, the size of the light-receiving surface of the light detection unit 5 is not particularly limited, and the light-receiving surface of the light detection element may be larger than the opening of the well 2. Alternatively, in another example, the light irradiator 4 causes only a portion of the first light P1 and the second light P2 to pass through the region 25, and the light detection unit 5 selectively detects only the portion of the first light P1 and the second light P2. This type of configuration is employed, for example, when the light irradiation unit 4 includes a surface-emitting LED. In this case, the size of the light-receiving surface of the light detection unit 5 is limited so that only a portion of each of the first light P1 and the second light P2 can be selectively detected.

[0044] The light detection unit 5 may include a single light detection element that detects the light intensity of both the first light P1 and the second light P2. In this case, the light detection element may be composed of, for example, semiconductor quantum dots made of PbS, InAs, or the like and having a diameter of 3 nm to 13 nm, or an organic semiconductor. Alternatively, the light detection unit 5 may include a first light detection element that detects the light intensity of the first light P1, and a second light detection element that is provided separately from the first light detection element and detects the light intensity of the second light P2. In this case, the light detection element may be composed of semiconductor quantum dots, an organic semiconductor, Si, InGaAs, graphene, or a carbon nanotube.

[0045] 6, 7, and 8 are diagrams showing various configuration examples of the light detection unit 5. The light detection unit 5A shown in FIGS. 6(a) and 6(b) has a first light detection element 51 and a second light detection element 52. FIG. 6(a) shows a case where the optical axis of the first light P1 coincides with the optical axis of the second light P2, while FIG. 6(b) shows a case where the optical axis of the first light P1 is separated from the optical axis of the second light P2. In this example, the second light detection element 52 is disposed between the first light detection element 51 and the well 2. When viewed from the first direction B1, the second light detection element 52 overlaps with the first light detection element 51. The first light detection element 51 is sensitive to the first wavelength λ1 and detects the light intensity of the first light P1. The second light detection element 52 is mainly sensitive to the second wavelength λ2 and detects the light intensity of the second light P2. The second photodetector element 52 has a much smaller sensitivity to the first wavelength λ1 than to the second wavelength λ2, and transmits the first light P1. The arrangement of the first photodetector element 51 may be interchanged with the arrangement of the second photodetector element 52. In that case, the first photodetector element 51 has a much smaller sensitivity to the second wavelength λ2 than to the first wavelength λ1, and transmits the second light P2.

[0046] The light detection unit 5B shown in Figures 7(a) and 7(b) has a first light detection element 51 and a second light detection element 52. Figure 7(a) shows a case where the optical axis of the first light P1 coincides with the optical axis of the second light P2, and Figure 7(b) shows a case where the optical axis of the first light P1 is separated from the optical axis of the second light P2. In this example, the second light detection element 52 is disposed closer to the well 2 than the first light detection element 51. However, unlike the example in Figure 6, when viewed from the first direction B1, the second light detection element 52 does not overlap (or slightly overlaps) with the first light detection element 51, and is in close proximity to the first light detection element 51.

[0047] The light detection unit 5C shown in Figures 8(a) and 8(b) has a first light detection element 51 and a second light detection element 52. Figure 8(a) shows a case where the optical axis of the first light P1 coincides with the optical axis of the second light P2, and Figure 8(b) shows a case where the optical axis of the first light P1 is separated from the optical axis of the second light P2. In this example, the distance from the second light detection element 52 to the well 2 is the same as the distance from the first light detection element 51 to the well 2. When viewed from the first direction B1, the second light detection element 52 is close to the first light detection element 51.

[0048] In the examples shown in FIGS. 7(a), 7(b), 8(a), and 8(b), a portion of the first light P1 is incident on the first photodetector element 51, and the remainder of the first light P1 is incident on the second photodetector element 52. Then, a portion of the second light P2 is incident on the second photodetector element 52, and the remainder of the second light P2 is incident on the first photodetector element 51. The first photodetector element 51 has a much lower sensitivity to the second wavelength λ2 than to the first wavelength λ1, and mainly detects the light intensity of the first light P1. The second photodetector element 52 has a much lower sensitivity to the first wavelength λ1 than to the second wavelength λ2, and mainly detects the light intensity of the second light P2.

[0049] Referring again to FIG. 1, the calculation unit 6 is connected to the light detection unit 5 by wire or wirelessly. The calculation unit 6 calculates the concentration of the sample in the liquid 3 based on the optical path length of the first light P1 in the liquid 3, which is calculated based on the first absorbance, which is the absorbance of the liquid 3 for the first light P1, and the second absorbance, which is the absorbance of the liquid 3 for the second light P2. Specifically, the absorbance is calculated using the following formula (1): where A is the absorbance, I0 is the amount of incident light, I is the amount of transmitted light, ε is the molar absorption coefficient, c is the concentration, and l is the optical path length.

number

number

number

[0050] The first absorbance A1 obtained using the first light P1, which is not absorbed by the sample, does not depend on the concentration of the sample. Therefore, the concentration c1 is considered to be approximately constant. Therefore, the optical path length l can be calculated from equation (2). Then, the sample concentration c2 can be calculated from equation (3) using the calculated optical path length l.

[0051] The calculation unit 6 may be configured by a computer. The computer physically includes memory such as RAM and ROM, a processor (calculation circuit) such as a CPU, a communication interface, a storage unit such as a hard disk, and a display unit such as a display. The computer is, for example, a personal computer, a cloud server, or a smart device (smartphone, tablet terminal, etc.). The computer functions as the calculation unit 6 by executing a program stored in the memory in the CPU of the computer system.

[0052] 9 is a flowchart showing a concentration measurement method according to this embodiment. As shown in FIG. 9, the concentration measurement method according to this embodiment includes a storing step ST1, a light detecting step ST2, and a calculating step ST3. This concentration measurement method is carried out using, for example, the concentration measuring device 1 described above.

[0053] In the storing step ST1, the liquid 3 is stored in the internal region 24 of the well 2. This operation is performed by the user of the concentration measuring device 1. In the light detecting step ST2, the first light P1 and the second light P2 are irradiated onto the liquid 3 so that they pass through both the bottom 22 and the liquid surface 3a, and the light intensities of the first light P1 and the second light P2 that have passed through the liquid 3 are detected. In the light detecting step ST2, the light intensities of the first light P1 and the second light P2 that have passed through the center of the internal region 24 or a position separated from the center of the internal region 24 by a distance of ¼ or less of the inner diameter L of the sidewall 21, as viewed from the first direction B1, are detected. In the light detecting step ST2, a single light source that outputs both the first light P1 and the second light P2 may be used. Alternatively, a first light source 41 that outputs the first light P1 and a second light source 42 that is provided separately from the first light source 41 and outputs the second light P2 may be used. Furthermore, in the light detection step ST2, a single light detection element that detects the light intensities of both the first light P1 and the second light P2 may be used, or a first light detection element 51 that detects the light intensity of the first light P1 and a second light detection element 52 that detects the light intensity of the second light P2 may be used. In the calculation step ST3, in accordance with the above-mentioned formulas (2) and (3), the concentration c2 of the sample in the liquid 3 is calculated based on the optical path length l of the first light P1 in the liquid 3, which is calculated based on the first absorbance A1, which is the absorbance of the liquid 3 for the first light P1, and the second absorbance A2, which is the absorbance of the liquid 3 for the second light P2.

[0054] The effects obtained by the concentration measurement device 1 and concentration measurement method according to the present embodiment described above will be described. The liquid surface 3a of the liquid 3 contained in the well 2 is not flat but has a meniscus due to surface tension and other factors. As shown in FIG. 1 , the height of the liquid surface 3a is highest at the periphery of the liquid surface 3a and decreases toward the center of the liquid surface 3a. The rate of change in the height of the liquid surface 3a in the radial direction of the well 2 is greatest at the periphery of the liquid surface 3a and decreases toward the center of the liquid surface 3a. In other words, the height of the liquid surface 3a is more stable toward the center of the liquid surface 3a. The concentration measurement device 1 and concentration measurement method according to the present embodiment detect the light intensities of the first light P1 and the second light P2 that have passed through the center of the internal region 24 or a position separated from the center of the internal region 24 by a distance equal to or less than ¼ of the inner diameter L of the sidewall 21, as viewed from the first direction B1. In this way, by detecting the light intensities of the first light P1 and the second light P2 passing through the vicinity of the center of the liquid surface 3a, the influence of the meniscus is reduced, and the optical path length l of the first light P1 in the liquid 3 can be made closer to the optical path length l of the second light P2 in the liquid 3. Therefore, the measurement accuracy of the concentration c2 of the sample calculated by the formulas (2) and (3) can be improved.

[0055] In addition, in the concentration measurement device 1 and the concentration measurement method of this embodiment, the absorbance of the sample at the first wavelength λ1 is 0.005 or less (molar extinction coefficient is 9×10 5 The absorbance of water at the first wavelength λ1 is 0.2 or more (molar absorption coefficient is 0.4 [L / mol cm] or more), and the absorbance of the sample at the second wavelength λ2 is 0.05 or more (molar absorption coefficient is 9 × 10 6 The absorbance of water at the second wavelength λ2 is 0.005 or less (molar extinction coefficient of 0.002 [L / mol cm] or less). In this way, the absorption of water for the first light P1 is much greater than the absorption of the sample for the first light P1, and the absorption of the sample for the second light P2 is much greater than the absorption of water for the second light P2, which further improves the accuracy of measuring the sample concentration.

[0056] In addition, the smaller the inner diameter L of the well 2, the greater the curvature of the liquid surface due to the meniscus. Furthermore, the appearance of the liquid surface 3a when the liquid 3 is first introduced is significantly different from when the liquid 3 is removed and then reintroduced. Furthermore, the smaller the area of ​​the bottom 22 of the well 2, the greater the change in the height of the liquid surface 3a due to an increase in volume caused by the inclusion of air bubbles. As a result, the optical path lengths l of the first light P1 and the second light P2 are more likely to fluctuate. As in this embodiment, by measuring the optical path length l using a first wavelength λ1 for measuring the optical path length l, separate from the second wavelength λ2 for measuring the sample, the measurement accuracy of the sample concentration c2 can be improved even if the state of the liquid surface 3a changes or air bubbles are introduced.

[0057] As described above, the absorbance of water at the first wavelength λ1 is 2.0 or less (molar absorption coefficient is 4 [L / mol cm] or less), and the absorbance of the sample at the second wavelength λ2 is 1.5 or less (molar absorption coefficient is 3 × 10 10 In this way, the absorption of the first light P1 by water and the absorption of the second light P2 by the sample are not too large, thereby reducing noise due to the influence of stray light and further improving the measurement accuracy of the sample concentration.

[0058] As described above, the absorbance of water at the first wavelength λ1 may be 0.5 or more and 1.0 or less (molar extinction coefficient: 1 [L / mol cm] or more and 2 [L / mol cm] or less). In this case, the difference between the absorption of the water for the first light P1 and the absorption of the sample for the first light P1 becomes even greater, and noise due to the influence of stray light can be further reduced, thereby further improving the accuracy of measuring the sample concentration.

[0059] As described above, the absorbance of the sample at the first wavelength λ1 is 0.002 or less (the molar extinction coefficient is 1×10 6 In this case, the difference between the absorption of the first light P1 by water and the absorption of the first light P1 by the sample becomes even larger, thereby further improving the accuracy of measuring the sample concentration.

[0060] As described above, the absorbance of the sample at the second wavelength λ2 is 0.3 or more and 1.0 or less (molar extinction coefficient is 6×10 7 [L / mol·cm] or more 2×10 10 In this case, the difference between the absorption of the second light P2 by the sample and the absorption of the second light P2 by water becomes even larger, and noise due to the influence of stray light can be further reduced, thereby further improving the measurement accuracy of the sample concentration.

[0061] As described above, the absorbance of water at the second wavelength λ2 may be 0.002 or less (molar extinction coefficient 0.001 [L / mol cm] or less). In this case, the difference between the absorbance of the sample for the second light P2 and the absorbance of water for the second light P2 becomes even greater, thereby further improving the accuracy of measuring the sample concentration.

[0062] As in this embodiment, the inner diameter L of the sidewall 21 may be 10 mm or less. When using a well 2 with such a small inner diameter L, the influence of the meniscus becomes large and the optical path length is likely to vary, so the concentration measurement device 1 and concentration measurement method according to this embodiment are effective.

[0063] As described above, the light irradiation unit 4 may include a single light source that outputs both the first light P1 and the second light P2. Similarly, in the light detection step ST2, a single light source that outputs both the first light P1 and the second light P2 may be used. In this case, the number of light sources can be reduced, simplifying the device configuration. In addition, since the passage position of the first light P1 and the passage position of the second light P2 coincide with or are close to each other, the measurement accuracy can be further improved.

[0064] As described above, the light irradiation unit 4 may include a first light source 41 that outputs the first light P1 and a second light source 42 that outputs the second light P2 and is provided separately from the first light source 41. Similarly, the light detection step ST2 may use the first light source 41 that outputs the first light P1 and the second light source 42 that is provided separately from the first light source 41 and outputs the second light P2. In this case, the wavelengths of the first light source 41 and the second light source 42 can be set individually, thereby increasing the degree of freedom in wavelength selection of the first wavelength λ1 and the second wavelength λ2.

[0065] As described above, the light detection unit 5 may include a single light detection element that detects the light intensities of both the first light P1 and the second light P2. Similarly, in the light detection step ST2, a single light detection element that detects the light intensities of both the first light P1 and the second light P2 may be used. In this case, the number of light detection elements can be reduced, simplifying the device configuration. In addition, it is easy to make the passage position of the first light P1 and the passage position of the second light P2 coincide with or close to each other, further improving measurement accuracy.

[0066] As described above, the light detection unit 5 may include a first light detection element 51 that detects the light intensity of the first light P1 and a second light detection element 52 that detects the light intensity of the second light P2. Similarly, in the light detection step ST2, the first light detection element 51 that detects the light intensity of the first light P1 and the second light detection element 52 that detects the light intensity of the second light P2 may be used. In this case, the wavelength sensitivity characteristics can be set individually for the first light detection element 51 and the second light detection element 52, thereby increasing the degree of freedom in wavelength selection of the first wavelength λ1 and the second wavelength λ2.

[0067] As described above, the light intensities of the first light P1 and the second light P2 may be detected after passing through the center of the internal region 24 or a position separated from the center of the internal region 24 by a distance equal to or less than 1 / 6 of the inner diameter L of the side wall 21, as viewed from the first direction B1. In this case, the detected first light P1 and second light P2 are closer to the center of the liquid surface 3a, which further reduces the influence of the meniscus and makes it possible to make the optical path length l of the first light P1 in the liquid 3 closer to the optical path length l of the second light P2 in the liquid 3. This further improves the accuracy of measuring the sample concentration.

[0068] As described above, the area of ​​overlap A between the first spot P1s and the second spot P2s as viewed from the first direction B1 may be 35% or more of the area of ​​the first spot P1s and 35% or more of the area of ​​the second spot P2s. In this case, by detecting the first absorbance A1 and the second absorbance A2 in the overlap A between the first spot P1s and the second spot P2s, it is possible to reduce measurement errors in the optical path length l caused by the separation between the optical axes of the first light P1 and the second light P2. This further improves the accuracy of sample concentration measurement.

[0069] As described above, the diameter D1 of the first spot P1s and the diameter D2 of the second spot P2s may be equal to or less than one-third of the inner diameter L of the side wall 21. In this way, by ensuring that the diameter D1 of the first spot P1s and the diameter D2 of the second spot P2s are not too large, the influence of stray light can be reduced and the measurement accuracy of the sample concentration can be further improved. In particular, when the inner diameter L of the side wall 21 is, for example, 6.6 mm or more, it is more effective that the diameter D1 of the first spot P1s and the diameter D2 of the second spot P2s are equal to or less than 2 mm.

[0070] [Variations] FIG. 10 is a diagram schematically illustrating the configuration of a concentration measuring device 1A according to a modification of the above embodiment. The concentration measuring device 1A according to this modification includes a well plate 23 in which a plurality of wells 2 having the same structure as in the above embodiment are arranged side by side. A light irradiating unit 4 irradiates both a first light P1 and a second light P2 onto each of the liquids 3 in the plurality of wells 2. A light detecting unit 5 detects the light intensities of the first light P1 and the second light P2 that have passed through the liquids 3 in the plurality of wells 2. A calculating unit 6 calculates the concentration of the sample in each of the plurality of wells 2.

[0071] According to this modification, the sample concentrations of a plurality of liquids 3 can be measured simultaneously, improving the efficiency of the measurement work. In addition, measurement errors due to differences in optical path lengths between a plurality of wells 2 can be reduced.

[0072] The concentration measurement device and concentration measurement method according to the present disclosure are not limited to the above-described embodiment, and various other modifications are possible. For example, although the above embodiment illustrates a case where the inner diameter L of the side wall 21 of the well 2 is 10 mm or less, the inner diameter L may be greater than 10 mm.

[0073] The concentration measurement device and concentration measurement method according to the present disclosure can also be expressed as follows. [A1] A concentration measuring device according to another aspect of the present disclosure, a well having a cylindrical side wall extending along a first direction and a bottom portion closing one end of the cylindrical side wall, the well containing a liquid in which a sample is dissolved or suspended in water in an internal region formed by the side wall and the bottom portion; a light irradiation unit that irradiates the liquid with a first light having a first wavelength and a second light having a second wavelength so that the light passes through both the bottom of the well and the liquid surface; a light detection unit that detects the light intensities of the first light and the second light that have passed through the liquid; and a calculation unit that calculates the concentration of the sample in the liquid based on the optical path length of the first light in the liquid calculated based on a first extinction coefficient, which is the extinction coefficient of the liquid for the first light, and a second extinction coefficient, which is the extinction coefficient of the liquid for the second light. The light detection unit detects the light intensity of the first light and the second light that pass through the center of the internal region or a position that is separated from the center of the internal region by a distance of less than 1 / 4 of the inner diameter of the side wall when viewed from the first direction. Furthermore, a concentration measurement method according to another aspect of the present disclosure includes: a containing step of containing a liquid in which a sample is dissolved or suspended in water in an internal region formed by a cylindrical side wall and a bottom portion of a well having a cylindrical side wall extending along a first direction and a bottom portion closing one end of the cylindrical side wall; a light detection step of irradiating the liquid with first light having a first wavelength and second light having a second wavelength so that the light passes through both the bottom of the well and the liquid surface of the liquid, and detecting the light intensities of the first light and the second light that have passed through the liquid; and a calculation step of calculating the concentration of the sample in the liquid based on the optical path length of the first light in the liquid calculated based on a first extinction coefficient, which is the extinction coefficient of the liquid for the first light, and based on a second extinction coefficient, which is the extinction coefficient of the liquid for the second light. In the light detection step, the light intensity of the first light and the second light that pass through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 4 or less of the inner diameter of the side wall when viewed from the first direction is detected. In the concentration measurement device and the concentration measurement method, the molar absorption coefficient of the sample at the first wavelength is 9×10 5 The molar absorption coefficient of water at the first wavelength is 0.4 [L / mol cm] or less. The molar absorption coefficient of the sample at the second wavelength is 9×10 6 The molar absorption coefficient of water at the second wavelength is 0.002 [L / mol cm] or less. [A2] In the concentration measurement device and concentration measurement method of [A1] above, the absorption coefficient of water at the first wavelength is 4 [L / mol cm] or less, and the absorption coefficient of the sample at the second wavelength is 3 × 10 10 [L / mol·cm] or less. [A3] In the concentration measurement device and concentration measurement method according to [A1] and [A2] above, the absorption coefficient of water at the first wavelength may be 1 [L / mol·cm] or more and 2 [L / mol·cm] or less. [A4] In the concentration measurement device and the concentration measurement method according to [A1] to [A3] above, the extinction coefficient of the sample at the first wavelength is 1×10 6 [L / mol·cm] or less. [A5] In the concentration measurement device and the concentration measurement method according to [A1] to [A4] above, the extinction coefficient of the sample at the second wavelength is 6×10 7 [L / mol·cm] or more 2×10 10 [L / mol·cm] or less. [A6] In the concentration measuring device and the concentration measuring method according to the above [A1] to [A5], the absorption coefficient of water at the second wavelength may be 0.001 [L / mol·cm] or less. [A7] In the concentration measuring device and concentration measuring method according to the above [A1] to [A6], the cylindrical side wall may have an inner diameter of 10 mm or less. [A8] The concentration measuring devices of [A1] to [A7] above may include a well plate in which the well and another well having the same structure as the well are arranged side by side. The light irradiating unit may irradiate both the first light and the second light onto the liquid in the well and the liquid in the other well, respectively. The light detecting unit may detect the light intensities of the first light and the second light that have passed through the liquid in the well, and the light intensities of the first light and the second light that have passed through the liquid in the other well. The calculating unit may calculate the concentration of the sample in the well and the concentration of the sample in the other well. [A9] In the concentration measuring device according to any one of [A1] to [A8] above, the light irradiating section may include a single light source that outputs both the first light and the second light. [A10] In the concentration measuring device according to any one of [A1] to [A8] above, the light irradiating unit may include a first light source that outputs the first light, and a second light source that is provided separately from the first light source and outputs the second light. [A11] In the concentration measuring device according to any one of [A1] to [A10] above, the light detecting section may include a single light detecting element that detects the light intensity of both the first light and the second light. [A12] In the concentration measuring device according to any one of [A1] to [A10] above, the light detection unit may include a first light detection element that detects the light intensity of the first light, and a second light detection element that detects the light intensity of the second light. [A13] In the concentration measurement device and concentration measurement method of [A1] to [A12] above, when a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, the overlapping area of ​​the first spot and the second spot as viewed from the first direction may be 35% or more of the area of ​​the first spot and 35% or more of the area of ​​the second spot. [A14] In the concentration measuring device of [A1] to [A13] above, the light detection unit may detect the light intensity of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 6 or less of the inner diameter of the side wall when viewed from the first direction. [A15] In the concentration measurement device and concentration measurement method of [A1] to [A14] above, when a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, the diameters of the first spot and the second spot may be 1 / 3 or less of the inner diameter of the cylindrical side wall. [A16] In the concentration measurement device and concentration measurement method described above in [A15], the diameters of the first spot and the second spot may be 2 mm or less. [Explanation of symbols]

[0074] 1, 1A...concentration measuring device, 2...well, 3...liquid, 3a...liquid surface, 4, 4A to 4E...light irradiation unit, 5, 5A to 5C...light detection unit, 6...calculating unit, 21...side wall, 22...bottom, 23...well plate, 24...internal region, 25...region, 40...light source, 41...first light source, 42...second light source, 44...optical fiber coupler, 45...lens, 47...diffraction grating, 48...aperture, 49...integrating sphere, 51...first light detection Output element, 52...second light detection element, 431-433...mirrors, 461-463...optical fibers, A...overlap, B1...first direction, D1, D2...diameter, E1, E2...distance, G1, G2...curve, L...inner diameter, P1...first light, P1s...first spot, P2...second light, P2s...second spot, P3...third light, Q...center line, ST1...accommodation step, ST2...light detection step, ST3...calculation step.

Claims

1. a well having a cylindrical side wall extending along a first direction and a bottom portion closing one end of the cylindrical side wall, the well containing a liquid in which a sample is dissolved or suspended in water in an internal region formed by the side wall and the bottom portion; a light irradiation unit that irradiates the liquid with a first light having a first wavelength and a second light having a second wavelength so that the light passes through both the bottom of the well and the liquid surface; a light detection unit that detects the light intensities of the first light and the second light that have passed through the liquid; a calculation unit that calculates a concentration of the sample in the liquid based on an optical path length of the first light in the liquid calculated based on a first absorbance that is an absorbance of the liquid to the first light, and a second absorbance that is an absorbance of the liquid to the second light; Equipped with the absorbance of the sample at the first wavelength is 0.005 or less, and the absorbance of water at the first wavelength is 0.2 or more; the absorbance of the sample at the second wavelength is 0.05 or more, and the absorbance of water at the second wavelength is 0.005 or less; The light detection unit detects the light intensity of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of less than 1 / 4 of the inner diameter of the side wall when viewed from the first direction.

2. 2. The concentration measuring device according to claim 1, wherein the absorbance of water at the first wavelength is 2.0 or less, and the absorbance of the sample at the second wavelength is 1.5 or less.

3. 2. The concentration measuring device according to claim 1, wherein the absorbance of water at the first wavelength is equal to or greater than 0.5 and equal to or less than 1.

0.

4. 2. The concentration measurement device according to claim 1, wherein the absorbance of the sample at the first wavelength is 0.002 or less.

5. 2. The concentration measuring device according to claim 1, wherein the absorbance of the sample at the second wavelength is equal to or greater than 0.3 and equal to or less than 1.

0.

6. 2. The concentration measuring device according to claim 1, wherein the absorbance of water at the second wavelength is 0.002 or less.

7. 7. The concentration measuring device according to claim 1, wherein the cylindrical side wall has an inner diameter of 10 mm or less.

8. a well plate in which the well and another well having the same structure as the well are arranged side by side; the light irradiation unit irradiates the liquid in the well and the liquid in the other well with both the first light and the second light, the light detection unit detects the light intensities of the first light and the second light that have passed through the liquid in the well, and the light intensities of the first light and the second light that have passed through the liquid in the other well; 7. The concentration measuring device according to claim 1, wherein the calculation unit calculates the concentration of the sample in the well and the concentration of the sample in the other well.

9. 7. The concentration measuring device according to claim 1, wherein the light irradiating unit includes a single light source that outputs both the first light and the second light.

10. The concentration measuring device according to any one of claims 1 to 6, wherein the light irradiation unit includes a first light source that outputs the first light, and a second light source that outputs the second light and is provided separately from the first light source.

11. 7. The concentration measuring device according to claim 1, wherein the light detecting section includes a single light detecting element that detects the light intensity of both the first light and the second light.

12. The concentration measuring device according to any one of claims 1 to 6, wherein the light detection unit includes a first light detection element that detects the light intensity of the first light and a second light detection element that detects the light intensity of the second light.

13. A concentration measuring device according to any one of claims 1 to 6, wherein when a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, the overlapping area of ​​the first spot and the second spot as viewed from the first direction is 35% or more of the area of ​​the first spot and 35% or more of the area of ​​the second spot.

14. The concentration measuring device according to any one of claims 1 to 6, wherein the light detection unit detects the light intensity of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 6 or less of the inner diameter of the side wall when viewed from the first direction.

15. 7. The concentration measuring device according to claim 1, wherein a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, and the diameters of the first spot and the second spot are 1 / 3 or less of the inner diameter of the cylindrical side wall.

16. 16. The concentration measuring device according to claim 15, wherein the first spot and the second spot have a diameter of 2 mm or less.

17. a containing step of containing a liquid in which a sample is dissolved or suspended in water in an internal region formed by a cylindrical side wall and a bottom portion of a well having a cylindrical side wall extending along a first direction and a bottom portion closing one end of the cylindrical side wall; a light detection step of irradiating the liquid with first light having a first wavelength and second light having a second wavelength so that the light passes through both the bottom of the well and the liquid surface of the liquid, and detecting the light intensities of the first light and the second light that have passed through the liquid; a calculation step of calculating a concentration of the sample in the liquid based on an optical path length of the first light in the liquid calculated based on a first absorbance that is an absorbance of the liquid to the first light, and a second absorbance that is an absorbance of the liquid to the second light; Equipped with the absorbance of the sample at the first wavelength is 0.005 or less, and the absorbance of water at the first wavelength is 0.2 or more; the absorbance of the sample at the second wavelength is 0.05 or more, and the absorbance of water at the second wavelength is 0.005 or less; In the light detection step, the light intensities of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of less than 1 / 4 of the inner diameter of the side wall when viewed from the first direction are detected.

18. 18. The concentration measurement method according to claim 17, wherein the absorbance of water at the first wavelength is 2.0 or less, and the absorbance of the sample at the second wavelength is 1.5 or less.

19. 18. The concentration measurement method according to claim 17, wherein the absorbance of water at the first wavelength is equal to or greater than 0.5 and equal to or less than 1.

0.

20. 18. The concentration measurement method according to claim 17, wherein the absorbance of the sample at the first wavelength is 0.002 or less.

21. 18. The concentration measurement method according to claim 17, wherein the absorbance of the sample at the second wavelength is 0.3 or more and 1.0 or less.

22. 18. The concentration measurement method according to claim 17, wherein the absorbance of water at the second wavelength is 0.002 or less.

23. The concentration measurement method according to any one of claims 17 to 22, wherein the cylindrical side wall has an inner diameter of 10 mm or less.

24. 23. The concentration measuring method according to claim 17, wherein the light detecting step uses a single light source that outputs both the first light and the second light.

25. 23. The concentration measurement method according to claim 17, wherein the light detection step uses a first light source that outputs the first light and a second light source that outputs the second light and is provided separately from the first light source.

26. 23. The concentration measuring method according to claim 17, wherein the light detecting step uses a single light detecting element that detects the light intensity of both the first light and the second light.

27. The concentration measurement method according to any one of claims 17 to 22, wherein the light detection step uses a first light detection element that detects the light intensity of the first light and a second light detection element that detects the light intensity of the second light.

28. 23. The concentration measurement method according to claim 17, wherein when a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, an overlapping area of ​​the first spot and the second spot as viewed from the first direction is 35% or more of an area of ​​the first spot and 35% or more of an area of ​​the second spot.

29. 23. The concentration measurement method according to claim 17, wherein in the light detection step, the light intensities of the first light and the second light that have passed through the center of the internal region or a position that is separated from the center of the internal region by a distance of 1 / 6 or less of the inner diameter of the side wall when viewed from the first direction are detected.

30. 23. The concentration measurement method according to claim 17, wherein a region of the first light having a light intensity of 36.8% or more of the peak intensity of the first light is defined as a first spot, and a region of the second light having a light intensity of 36.8% or more of the peak intensity of the second light is defined as a second spot, and the diameters of the first spot and the second spot are 1 / 3 or less of the inner diameter of the cylindrical side wall.

31. 31. The concentration measurement method according to claim 30, wherein the diameter of the first spot and the second spot is 2 mm or less.

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