Capillary electrophoresis device

Abstract

A capillary electrophoresis device has a light source, a plurality of capillaries, a light detection section, and a plurality of detection optical fibers having one end surface disposed in association with any one of the capillaries and the other end surface connected to the light detection section, the light detection section selectively detecting light from the center portion of the detection optical fibers.

Description

Technical Field

[0001] This invention relates to capillary electrophoresis apparatus. Background Technology

[0002] Biopharmaceuticals possess superior effects compared to low-molecular-weight pharmaceuticals, such as antibody molecules modified with glycans that show efficacy against specific targets like cancer and rare diseases. Low-molecular-weight drugs are synthesized through chemical reactions, while biopharmaceuticals are generated using cellular biological functions; therefore, the molecular structure of the product is affected by minute changes in culture conditions. Immunoglobulin G (IgG), a representative biopharmaceutical, is a large molecule with a complex structure and a molecular weight of around 150,000, making structural inhomogeneity almost impossible to prevent. Therefore, quality control technologies used to confirm the safety and efficacy of formulations in biopharmaceuticals play a more crucial role.

[0003] Due to the complex structure of target substances, the testing items for biopharmaceuticals are diverse. However, capillary electrophoresis is used in confirmatory tests to identify the main component of the tested substance as the target substance and in purity tests to evaluate the content of impurities. In a capillary electrophoresis apparatus, a sample, such as an antibody, is injected into a capillary and subjected to electrophoresis. The sample is separated according to its molecular weight and charge, and detected by a detection unit located near the end of the capillary. As a detection method, optical methods such as ultraviolet (UV) absorption, native fluorescence (NF), and laser-induced fluorescence (LIF) are widely used.

[0004] An example of a capillary electrophoresis apparatus is disclosed in Patent Document 1.

[0005] LIF (Liquid Fiber Ion) measurement is the most sensitive detection method and has been used since ancient times for detecting glycans in antibody drugs that are difficult to detect using UV absorption and NF (Natural Fluorescence), as well as nucleic acids such as DNA. In LIF measurement, a laser is used as the light source. By utilizing the laser's directionality and the lensing effect of capillaries, multiple capillaries can be simultaneously illuminated with the laser. This allows for the analysis of multiple samples at once, thus enabling high-throughput analysis.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-133373 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In LIF measurements, multiple capillaries can be analyzed simultaneously. However, to detect fluorescence generated from multiple capillaries, multiple lenses or lenses as large as possible corresponding to the multiple capillaries are required, which easily leads to the scaling up of the device. Therefore, the inventors designed an optical system to recover fluorescence by placing optical fibers close to each capillary. In such an optical system, fluorescence can be detected without placing lenses near the capillaries, and the constraints of the positional relationship between the capillaries and the detector are eliminated, increasing the degree of design freedom and thus enabling device miniaturization.

[0011] However, in such detection optical systems, a problem arises where large crosstalk occurs because the fluorescence generated from a specific capillary is incident on the optical fiber corresponding to the adjacent capillary.

[0012] The present invention was made in view of the above-mentioned problems, and its object is to provide a small and low crosstalk capillary electrophoresis device.

[0013] Methods for solving problems

[0014] An example of the capillary electrophoresis apparatus of the present invention is characterized by having: a light source; a plurality of capillaries; a light detection unit; and a plurality of detection optical fibers, one end face of which is associated with any one of the capillaries and the other end face of which is connected to the light detection unit, wherein the light detection unit selectively detects light at the center of the detection optical fiber.

[0015] Invention Effects

[0016] According to the present invention, a capillary electrophoresis apparatus that is smaller and has less crosstalk than before can be provided. Furthermore, depending on the circumstances, a capillary electrophoresis apparatus that is less expensive than before can also be provided.

[0017] Other issues, structures, and effects not mentioned above become clear through the following description of implementation methods. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the structure of the capillary electrophoresis apparatus according to Embodiment 1 of the present invention.

[0019] Figure 2 This is an explanation Figure 1 A schematic diagram of the structure of the component detection section of a capillary electrophoresis apparatus.

[0020] Figure 3 This is a schematic diagram illustrating the mechanism that generates crosstalk.

[0021] Figure 4 This is an example of the light intensity distribution at the light-emitting end of an optical fiber used for detection.

[0022] Figure 5This is an example of the simulation results of signal strength and crosstalk in Example 1.

[0023] Figure 6 These are simulation results related to the propagation efficiency of the optical fiber and the incident angle dependence of the light intensity distribution at the light emission end.

[0024] Figure 7 It is a diagram illustrating the optical path of light rays incident on an optical fiber.

[0025] Figure 8 This is the result of the calculation of the incident angle dependence of the optical fiber propagation efficiency.

[0026] Figure 9 This is a schematic diagram of the optical path of light propagating in an optical fiber.

[0027] Figure 10 It is the calculated radius of the region where the light intensity distribution is zero after the optical fiber propagates.

[0028] Figure 11 This is a schematic diagram illustrating the structure of the component detection section of the capillary electrophoresis apparatus according to Embodiment 2 of the present invention.

[0029] Figure 12 This is a schematic diagram illustrating the structure of the component detection section of the capillary electrophoresis apparatus according to Embodiment 3 of the present invention.

[0030] Figure 13 This is a schematic diagram illustrating the structure of the component detection section of the capillary electrophoresis apparatus according to Embodiment 4 of the present invention. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0032] [Example 1]

[0033] <Basic Structure>

[0034] (Overall description of the electrophoresis apparatus)

[0035] Figure 1 This is a schematic diagram illustrating the structure of the capillary electrophoresis apparatus 1 according to this embodiment. Electrophoresis media and samples are respectively contained in the electrophoresis medium container 2 and multiple sample containers 3. Before measurement, multiple capillaries 5 included in the capillary array 11 are connected to these containers, and the electrophoresis medium and samples are sequentially injected into the multiple capillaries 5 via electrical elements, pressure, etc. Multiple injection-side electrode slots 4 and discharge-side electrode slots 7 are filled with buffer solution, which is then immersed in the capillaries 5 and electrodes 9 during electrophoresis.

[0036] If a voltage is applied through the high-voltage power supply 8, the molecules in the sample are separated by electrophoresis according to properties such as molecular weight and charge, and the capillary 5 moves from the injection side to the discharge side. When the moved molecules reach the component detection unit 6, they are detected by the optical unit. Although not shown, the capillary electrophoresis apparatus 1 also includes a pressure adjustment unit, a control unit, a signal processing unit, a display unit, and a recording unit.

[0037] (Explanation from the Ingredient Analysis Department)

[0038] Figure 2 This is an example of the structure of the component detection unit 6 in the electrophoresis apparatus 1. Excitation light emitted from the light source 101 irradiates multiple capillaries 102 along the arrangement direction of the capillary array 103. Thus, it is possible to use a single light source 101 to irradiate multiple capillaries 102 simultaneously with excitation light.

[0039] The component detection unit 6 includes a plurality of detection optical fibers 104. Each detection optical fiber 104 corresponds to one of the capillaries 102. One end face of each detection optical fiber 104 is configured in association with the corresponding capillary 102, for example, in the vicinity of the corresponding capillary 102. The specific range of "vicinity" can be considered by those skilled in the art. Figure 5 The relevant matters described later will be used to make appropriate decisions, for example, it can be set as follows: Figure 5 The range shown is (however, greater than 0. For example, less than 0.1 mm, less than 0.2 mm, less than 0.3 mm, less than 0.4 mm, or less than 0.5 mm). The other end face of each detection fiber 104 is connected to the photodetector 108.

[0040] When excitation light is irradiated onto the sample in the capillary 102, fluorescence (autofluorescence or fluorescence from a fluorescent dye) is generated from the sample. A portion of this fluorescence is coupled to a detection optical fiber 104 provided corresponding to each capillary 102. The fluorescence propagates in the detection optical fiber 104 and is guided to a photodetector 108 which includes a pinhole 105, a long-pass filter 106, and a photodetector 107.

[0041] When fluorescence is emitted into space from the detection optical fiber 104, the fluorescence at the periphery of the detection optical fiber 104 is blocked by the pinholes 105 provided at the emitting ends of each detection optical fiber 104, and only the fluorescence near the center is emitted into space. Afterwards, the fluorescence passes through the long-pass filter 106 and is detected by the photodetector 107.

[0042] Thus, the pinhole 105 functions as a selective light-blocking element, thereby allowing the light detection unit 108 to selectively detect light from the center portion of the detection optical fiber 104. Here, "center portion of the detection optical fiber 104" refers, for example, to a region containing the central axis in a cross-section orthogonal to the central axis of the detection optical fiber; specifically, it refers to a disk-shaped region centered on the central axis. Regarding the radius of the disk-shaped region, those skilled in the art can consider... Figure 5 The relevant matters described below will be used to make appropriate decisions.

[0043] The long-pass filter 106 is provided to prevent the detection of excitation light that is scattered by the capillary 102 and coupled to the detection fiber 104.

[0044] The pinhole 105 serves to suppress crosstalk between capillaries caused by the coupling of fluorescence generated from a specific capillary 102 with a detection fiber 104 other than the corresponding detection fiber 104.

[0045] like Figure 2 As shown in the pop-up window, at least one of the area and shape of the opening of the pinhole 105 (i.e., the area of ​​the detection fiber 104 selectively detected) can be changed. For example, it can be as follows: Figure 2 As in (a), (b), and (c), multiple pinholes with different opening sizes or shapes can be used interchangeably, or a single pinhole can be modified as in (a), (b), and (c) to change its opening size or shape. With such a structure, as described later, the balance between signal component loss suppression and crosstalk blocking can be adjusted. Furthermore, in other embodiments described later, the area of ​​the detection fiber 104 for selective detection can also be changed in this way.

[0046] Figure 3 This diagram illustrates an example of a crosstalk generation mechanism. Fluorescence generated from capillary 201 is incident on the corresponding detection fiber 203 (solid arrow) and detected as a signal component. Conversely, fluorescence is also directly or indirectly incident (dashed arrow) on the detection fiber 204 corresponding to the adjacent capillary 202, either by reflection from capillary 202, and detected as a crosstalk component. As shown, the crosstalk component tends to be incident on the fiber at a higher angle of incidence than the signal component.

[0047] Figure 4This is a ray tracing simulation of the intensity distribution of fluorescence generated inside capillary 201 after coupling and propagation with detection fibers 203 and 204 at the fiber exit end. The simulation conditions were set as follows: capillary inner diameter 50 μm, capillary outer diameter 150 μm, capillary distance 500 μm, and distance from the capillary surface to the incident end of the corresponding detection fiber 300 μm. Detection fibers 203 and 204 are multimode, with a core diameter of 400 μm, a cladding diameter of 420 μm, a numerical aperture of 0.5, and a length of 100 mm. Furthermore, the fluorescence emitting region within capillary 201 is cylindrical with a diameter of 50 μm and a height of 50 μm.

[0048] The light intensity at the emitting end of the detection fiber 203, corresponding to the signal component, tends to be locally concentrated in the center of the fiber. Conversely, the light intensity at the emitting end of the detection fiber 204, which is a crosstalk component, tends to be locally concentrated in the periphery of the fiber. This reflects the property of multimode optical fibers that light incident at low angles is locally concentrated in the center of the fiber, while light incident at high angles is locally concentrated in the periphery. This embodiment utilizes this property of the optical fiber to selectively detect light from the center of the detection fiber 104 through the pinhole 105, thereby suppressing crosstalk.

[0049] Figure 5 The results are obtained by simulating and evaluating the crosstalk suppression effect of this embodiment. As a reference example, the dependence of signal strength and crosstalk on the distance between the capillary and the fiber is shown when the core diameter c of the detection fiber is 400 μm and 200 μm, and when a pinhole with an aperture PH of 200 μm is provided at the emitting end of a 400 μm core diameter fiber as a specific structure of this embodiment.

[0050] Other simulation conditions and Figure 4 The situation is the same. The larger the core diameter c, the stronger the signal, but on the other hand, the greater the crosstalk.

[0051] The smaller the distance between the capillary and the optical fiber, the stronger the signal and the less crosstalk; therefore, it is preferable to keep it as small as possible. However, if it is too small, the optical fiber will come into contact with the capillary, increasing the risk of breakage. Therefore, it is practically preferable to separate the optical fiber and the capillary by several hundred micrometers or more.

[0052] For example, if the distance between the capillary and the fiber is greater than 200 μm, a large crosstalk of more than 2.2% will occur when the core diameter is 400 μm. If the core diameter is set to 200 μm, the signal strength decreases compared to the case with a core diameter of 400 μm, but the crosstalk is further reduced, reaching less than 0.5% when the distance between the fiber and the capillary is less than 0.3 mm.

[0053] On the other hand, when a 200μm pinhole is provided at the exit end of a 400μm core diameter optical fiber, which is a specific structure in this embodiment, the signal strength is greater and the crosstalk is equal to or less than that in the case of a 200μm core diameter fiber when the fiber-capillary distance is 200μm or more. This result means that, under the condition that the capillary-fiber distance is a certain degree, providing a pinhole at the exit end of a large core diameter optical fiber, as in this embodiment, is advantageous from the viewpoints of both signal strength and crosstalk compared to using only a small core diameter fiber.

[0054] Compared to the reference example with a core diameter of 400 μm, in this embodiment where a 200 μm pinhole is provided at the emitting end with a core diameter of 400 μm, the signal strength is reduced to about half, while crosstalk is suppressed to about 1 / 26 of the range of 4.13% to 0.16%. This is due to the pinhole blocking more crosstalk components compared to the signal components.

[0055] Crosstalk can also be suppressed by optimizing the core diameter and numerical aperture of the optical fiber, but in most cases, the available core diameter and numerical aperture of the optical fiber are limited, resulting in very low degrees of freedom for optimization. On the other hand, the aperture of the pinhole can be freely set, so the optimization freedom of this embodiment is high.

[0056] Next, the operating principle of this embodiment and the appropriate size of the light-blocking area will be explained in detail based on simulation and mathematical formulas. Figure 6 (a) is the simulation result of the optical propagation efficiency of the optical fiber (the proportion of incident light reaching the output end of the optical fiber) dependent on the angle of incidence.

[0057] The simulation was conducted using a multimode fiber with a core diameter of 200 μm, a cladding diameter of 220 μm, a numerical aperture of 0.5, and a length of 100 mm. The light propagation efficiency was approximately 1 up to an incident angle equivalent to 30 degrees of the fiber's numerical aperture, decreasing rapidly beyond 30 degrees. This is because, if the incident angle exceeds 30 degrees, the components that do not meet the total internal reflection condition within the fiber increase.

[0058] Figure 6 (b) shows the light intensity distribution at the fiber exit end at each incident angle. It can be seen that the intensity distribution within the fiber core is approximately uniform up to an incident angle of 30 degrees. Conversely, if the incident angle exceeds 30 degrees, the light intensity tends to be localized in the periphery. That is, the intensity of light incident at an angle larger than the equivalent numerical aperture of the fiber tends to be localized in the periphery of the fiber.

[0059] The principle behind this property is explained below using accompanying drawings. Figure 7 As shown, consider a coordinate system with the center of the fiber's input end as the origin. The z-axis is the central axis of the fiber. The x-axis and y-axis are mutually orthogonal axes in the radial direction of the fiber.

[0060] Considering the incident angle θ relative to the optical fiber in The incident ray of light. The unit direction vector k of the incident ray of light. in The unit direction vector k of the light rays after refraction on the fiber surface core They are represented by the following formulas respectively.

[0061] [Formula 1]

[0062]

[0063] [Formula 2]

[0064]

[0065] At this time, θ in and k core According to Snell's law, the following relationship is satisfied.

[0066] [Formula 3]

[0067] sinθ in =n core sinθ core …(Equation 3)

[0068] Where, n core U is the refractive index of the fiber core. Using a real number u satisfying -1 < u < 1 and the fiber core diameter c, uc / 2 represents the x-coordinate of the incident ray at the incident end of the fiber. The normal vector n of this incident ray to the core / cladding interface at the incident position is then expressed by the following formula.

[0069] [Formula 4]

[0070]

[0071] The angle of incidence α of light relative to the core / cladding interface is determined by the following formula.

[0072] [Formula 5]

[0073]

[0074] The conditions for total internal reflection of light at the core / cladding interface are:

[0075] [Formula 6]

[0076] n core sinα>n clad …(Equation 6)

[0077] When using equations 3 and 5, equation 6 can be expressed as:

[0078] [Formula 7]

[0079]

[0080] Furthermore, when the numerical aperture NA of the optical fiber is given by Equation 8 below, the total internal reflection condition of the light is finally expressed by Equation 9 below.

[0081] [Formula 8]

[0082]

[0083] [Formula 9]

[0084]

[0085] Equation 9 indicates that the closer the incident x position of the light ray is to the periphery of the optical fiber (the larger the absolute value of u), the wider the range of angles of the light ray that satisfy the condition of total internal reflection.

[0086] The upper limit θ of the incident angle used to ensure total internal reflection for light incident on the position u=0. c0 (The incident angle, equivalent to the NA of the optical fiber, is defined by the following formula.)

[0087] [Formula 10]

[0088] sinθ c0 =NA…(Formula 10)

[0089] With θ c0 The following incident light rays satisfy the condition of total internal reflection regardless of the incident x-position, but with θ... c0 When the light rays incident at the above angles reach a position a certain distance from the center, the condition for total internal reflection is satisfied. Solving equation 8 with respect to u yields the following equation.

[0090] [Formula 11]

[0091] u>u c …(Equation 11)

[0092] Here, θ c0 The light rays incident at the above angles only have an absolute value of u at the incident x position on the optical fiber. c Total internal reflection is satisfied when c / 2 or greater. Incident angle θ c0 The propagation efficiency P of the above light rays in the optical fiber is determined by the area of ​​the incident position of the optical fiber that satisfies the total internal reflection condition, and is given by the following formula.

[0093] [Formula 13]

[0094]

[0095] By performing the integration of Equation 13, we obtain the following formula.

[0096] [Formula 14]

[0097]

[0098] If we substitute equation 12 into equation 14, considering the incident angle θ c0 If all the following light rays satisfy the condition of total internal reflection, then relative to the angle of incidence θ in The propagation efficiency P can be expressed by the following formula.

[0099] [Formula 15]

[0100]

[0101] Figure 8 It is a comparison Figure 6 The results of the ray tracing simulation and the graph of the propagation efficiency expressed by Equation 13 are shown. It can be seen that the two are qualitatively consistent, and the theory relating to the incident angle dependence of the propagation efficiency of optical fibers mentioned above is appropriate.

[0102] Figure 9 This is a schematic diagram showing the trajectory of light rays propagating within an optical fiber as observed from the incident end. Figure 9 (a) represents the case where the incident position x of the light ray into the optical fiber is the center (u=0). Figure 9 (b) represents the case where the incident position x of the light ray into the optical fiber is at the periphery (u > 0). For example... Figure 9 As shown in (a), the incident light rays to the center are repeatedly reflected at the same position, passing through the center of the fiber each time. In contrast, as... Figure 9 As shown in (b), the incident angle of light rays incident on the periphery of the optical fiber increases towards the core / cladding interface, so it does not pass through the center of the optical fiber, but only propagates in the periphery.

[0103] Based on the above results, it can be concluded that at an angle (θ) equivalent to the NA of the optical fiber... c0 Light rays incident on an optical fiber at angles greater than NA satisfy the total internal reflection condition only when incident on the periphery of the fiber; light rays incident on the periphery of the fiber are locally present in the periphery. As a result, light rays incident on an optical fiber at angles greater than NA, after propagating in the fiber, are locally present in the periphery.

[0104] Next, the pinhole diameter in this embodiment will be explained. According to... Figure 6 The simulation results shown are at an incident angle of θ. c0 In the above case, for each incident angle, the radius of the central region where the light intensity is zero is calculated in the light intensity distribution at the fiber optic outlet. Figure 10 v is the radius of the region where the intensity distribution at the fiber exit end is zero, normalized to the fiber core radius c / 2. c With u as expressed by Equation 11c The results of comparing the incident angle dependence show that the two are roughly consistent.

[0105] Therefore, it can be said that θ c0 The incident light described above exists locally at the fiber optic exit end at a radius of approximately cu. c The region is above / 2. Therefore, the incident angle of the crosstalk component to be excluded into the optical fiber is set to... At that time, by adjusting the radius r of the pinhole p Setting it to Equation 16 below can eliminate this crosstalk component.

[0106] [Formula 16]

[0107]

[0108] In crosstalk, such as Figure 3 As shown by the dashed line, there are two components: one that is directly incident on the adjacent fiber (hereinafter referred to as the direct component) and the other that is incident on the adjacent fiber after reflection from the adjacent capillary. The latter component attenuates in intensity during reflection, so in the presence of the direct component, the direct component becomes dominant. Figure 3 The minimum incident angle of the direct component-oriented optical fiber is shown. It can be approximately represented by the following formula.

[0109] [Formula 17]

[0110]

[0111] Here, as Figure 3 As shown, p is the spacing between capillaries (the distance between the centers of the capillaries), d is the distance from the surface of the capillary to the light incident end of the optical fiber, and D out It is the outer diameter of the capillary. Also, for simplicity, let's assume the fluorescence originates from the center of the capillary.

[0112] For example, at p = 500 μm, d = 300 μm, D out =150μm, c=400μm ( Figure 5 (Simulation conditions for the reference example with c = 400 μm) degrees, and the pinhole radius r corresponding to that incident angle. p Assuming equality in Equation 16, the value is approximately 156 μm. That is, by setting the pinhole radius to approximately 156 μm, the loss of signal components can be minimized, and in principle, all direct components of crosstalk can be blocked.

[0113] [Example 2] (Setting up an imaging optical system)

[0114] Figure 11This is a schematic diagram showing an example of the structure of the component detection unit 6 in the capillary electrophoresis apparatus 1 of this embodiment. Furthermore, regarding... Figure 2 Components that are identical to those shown are labeled with the same symbols, and their descriptions are omitted. The difference between this embodiment and Embodiment 1 is that an imaging optical system 303 with lenses 301 and 302 is also provided in the light detection unit 108.

[0115] Similar to Example 1, excitation light emitted from the light source 101 illuminates multiple capillaries 102 along the arrangement direction of the capillary array 103. A portion of the fluorescence generated from the sample in the capillary 102 is coupled to a detection optical fiber 104 corresponding to each capillary 102. After propagating in the detection optical fiber 104, the fluorescence is emitted into space, converted into parallel light by the lens 301, and then focused by the lens 302 at the position of the pinhole 105 after passing through the long-pass filter 106. The pinhole 105 blocks the light emitted from the periphery of the emitting end of the detection optical fiber 104. As a result, the light emitted from the center of the emitting end of the detection optical fiber 104 is detected by the photodetector 107.

[0116] Thus, the light detection unit 108 of this embodiment includes an imaging optical system 303 that images the light emitted from the light emitting end of the detection optical fiber 104 at the position of the pinhole 105.

[0117] In this embodiment, by setting up the imaging optical system 303, the light emitted from the detection optical fiber 104 is converted into parallel light, so that the light can be incident approximately perpendicularly to the long-pass filter 106, and the performance degradation caused by the incident angle of the light to the long-pass filter 106 deviating from vertical (e.g., an increase in the transmittance of excitation light and a decrease in the transmittance of fluorescence) can be suppressed.

[0118] In addition, by setting the imaging magnification of the imaging optical system 303 to 1 or higher, that is, by magnifying and imaging the light emitted from the emitting end of the detection optical fiber 104 at the pinhole position, the required manufacturing accuracy or positional accuracy of the pinhole 105 can be alleviated.

[0119] [Example 3] (Using optical fiber for connection)

[0120] Figure 12 This is a schematic diagram showing an example of the structure of the component detection unit 6 in the capillary electrophoresis apparatus 1 of this embodiment. Furthermore, regarding... Figure 2 Components that are identical to those shown are labeled with the same symbols, and their descriptions are omitted. The difference between this embodiment and Embodiment 1 is that the optical detection unit 108 includes an optical fiber connector 401, a connecting optical fiber 402, a long-pass filter 106, and a photodetector 107.

[0121] Similar to Example 1, excitation light emitted from the light source 101 illuminates multiple capillaries 102 along the arrangement direction of the capillary array 103. A portion of the fluorescence generated from the sample in the capillary 102 is coupled to a detection optical fiber 104 corresponding to each capillary 102. After propagating in the detection optical fiber 104, the fluorescence is coupled to a connection optical fiber 402 connected to the detection optical fiber 104 via an optical fiber connector 401.

[0122] The core diameter of the connecting optical fiber 402 is set to be smaller than that of the detection optical fiber 104. Only light near the center of the emitting end of the detection optical fiber 104 couples with the connecting optical fiber 402 and is guided to the photodetector 107 after propagation. That is, the connecting optical fiber 402 serves the same function as the pinhole 105 in Embodiment 1. Here, the central axes of the detection optical fiber 104 and the connecting optical fiber 402 are positioned to coincide with each other by the optical fiber connector 401, which is a universal component. Therefore, in this embodiment, it is not necessary to align the central axes of the detection optical fiber 104 and the pinhole 105 as required in Embodiment 1, and it is easier to achieve the same performance as Embodiment 1.

[0123] The imaging optical system 303 of Embodiment 2 can also be combined. Figure 11 ) and the fiber optic cable 402 for connection with Example 3 ( Figure 12 For example, in Figure 12 Alternatively, an imaging optical system 303 can be used instead of the fiber optic connector 401. In this case, the imaging optical system 303 images the light emitted from the light-emitting end of the detection fiber 104 at the incident end of the connecting fiber 402.

[0124] In such a combination, by setting the imaging magnification of the imaging optical system 303 to 1 or higher, i.e., performing magnified imaging, the degree of freedom in the core diameter of the connecting optical fiber 402 is increased. For example, the core diameter of the connecting optical fiber 402 can be set to be equal to or larger than the core diameter of the detection optical fiber 104.

[0125] [Example 4] (Using an imaging element)

[0126] Figure 13 This is a schematic diagram showing an example of the structure of the component detection unit 6 in the capillary electrophoresis apparatus 1 of this embodiment. Furthermore, regarding... Figure 2 Components that are identical to those shown are labeled with the same symbols, and their descriptions are omitted. The difference between this embodiment and the first embodiment is that the light detection unit 108 includes an imaging optical system 303 (including microlens arrays 501 and 502), a long-pass filter 106, an imaging element 503, and a signal processing unit 504.

[0127] Similar to Example 1, excitation light emitted from the light source 101 illuminates multiple capillaries 102 along the arrangement direction of the capillary array 103. A portion of the fluorescence generated from the sample in the capillary 102 is coupled to a detection optical fiber 104 corresponding to each capillary 102. The imaging optical system 303 functions to image the light emitted from the emitting ends of all the detection optical fibers 104 onto the imaging element 503 (more precisely, for example, its light-receiving portion). Thus, the two-dimensional light intensity distribution of the fluorescence emitted from the detection optical fibers 104 is detected by the imaging element 503 and transmitted to the signal processing unit 504.

[0128] The signal processing unit 504 selectively processes the light from the center portion of the detection optical fiber 104 in the light detected by the imaging element 503. For example, it acquires and adds only the intensity of the light from the center portion as a signal, ignoring the intensity of other light. That is, in this embodiment, the signal processing unit 504 functions as the pinhole 105 in Embodiment 1.

[0129] In this embodiment, no pinholes or optical fibers are provided for connection; crosstalk can be suppressed solely through signal processing. Furthermore, the size of the detection area can be freely set by the signal processing unit 504, making it easy to optimize the relationship between signal strength and crosstalk magnitude according to the application.

[0130] As described above, the following description applies to various embodiments of the present invention.

[0131] One example of the present invention is a capillary electrophoresis apparatus comprising: a light source; a plurality of capillaries; a photodetector; and a plurality of detection optical fibers, one end face of which is associated with any one of the capillaries and the other end face of which is connected to the photodetector, wherein the photodetector selectively detects light at the center of the detection optical fiber.

[0132] By setting it to this structure, crosstalk can be suppressed.

[0133] As an example, the light detection unit may also have at least a light detector and a selective light-blocking element.

[0134] By setting it to this structure, crosstalk can be suppressed in a cheap and simple way.

[0135] As an example, the optical detection unit may also include at least a optical detector and an optical fiber for connection.

[0136] By setting the structure in this way, crosstalk can be stably suppressed.

[0137] As an example, the light detection unit may also include at least an imaging element and a signal processing unit, wherein the signal processing unit selectively processes the light from the center of the detection optical fiber in the light detected by the imaging element.

[0138] By configuring the structure in this way, crosstalk can be suppressed solely through the signal processing unit without using light-shielding components.

[0139] As an example, the light detection unit may also have an imaging optical system that images the light emitted from the light-emitting end of the detection optical fiber at the position of the selective light-shielding element.

[0140] By adopting such a structure, the configuration of components such as optical filters becomes easier, and by appropriately setting the imaging magnification, robustness against positional deviations of selective shading elements can be improved.

[0141] As an example, the optical detection unit may also have an imaging optical system that images the light emitted from the light-emitting end of the detection optical fiber at the incident end of the connecting optical fiber.

[0142] By adopting such a structure, the configuration of components such as optical filters becomes easier, and by appropriately setting the imaging magnification, robustness against positional deviations of the connecting optical fiber can be improved.

[0143] As an example, the core diameter of the connecting optical fiber can also be configured to be smaller than the core diameter of the detection optical fiber.

[0144] By designing it in this way, pinholes are not needed.

[0145] As an example, the light detection unit may also have an imaging optical system that enables light emitted from the light-emitting end of the detection optical fiber to image the imaging element.

[0146] By adopting this structure, the configuration of components such as optical filters becomes easier, and by appropriately setting the imaging magnification, the crosstalk suppression effect based on signal processing can be improved.

[0147] As an example, the optical detection unit may also be configured such that it selectively detects light in a region with a radius r or less from the center at the light-emitting end of the detection optical fiber.

[0148] Where r is given by the following formula.

[0149] [Formula 18]

[0150]

[0151]

[0152] Wherein, NA is the numerical aperture of the optical fiber used for detection.

[0153] c is the core diameter of the optical fiber used for detection.

[0154] p is the interval between the plurality of capillaries.

[0155] D out It is the outer diameter of the capillary.

[0156] d is the distance from the surface of the capillary to the light incident end of the corresponding detection optical fiber.

[0157] By configuring the structure in this way, the loss of signal components can be minimized, and crosstalk can be suppressed.

[0158] As an example, the optical detection unit may also be able to change at least one of the area and shape of the region of the detection optical fiber that is selectively detected.

[0159] By setting it up in this way, the detection sensitivity and crosstalk can be adjusted appropriately according to the application.

[0160] Symbol Explanation

[0161] 1: Capillary electrophoresis apparatus

[0162] 2: Electrophoresis medium container

[0163] 3: Sample container

[0164] 4: Injection side electrode groove

[0165] 5: Capillary

[0166] 6: Ingredient Testing Department

[0167] 7: Discharge side electrode groove

[0168] 8: High-voltage power supply

[0169] 9: Electrode

[0170] 11: Capillary Array

[0171] 101: Light Source

[0172] 102: Capillary

[0173] 103: Capillary Array

[0174] 104: Fiber optic cable for testing

[0175] 105: Pinhole (Selective Light-Shielding Element)

[0176] 106: Long-pass filter

[0177] 107: Photodetector

[0178] 108: Optical Detection Department

[0179] 201, 202: Capillary

[0180] 203, 204: Fiber optic cables for testing

[0181] 301, 302: Lenses

[0182] 303: Imaging Optical System

[0183] 401: Fiber Optic Connector

[0184] 402: Fiber optic cable for connection

[0185] 501: Microlens Array

[0186] 503: Camera element

[0187] 504: Signal Processing Department.

Claims

1. A capillary electrophoresis apparatus, characterized in that, The capillary electrophoresis device has: light source; Multiple capillaries; Optical detection department; as well as One end face is associated with any one of the capillaries, and the other end face is connected to a plurality of detection optical fibers connected to the optical detection unit. The photodetector selectively detects the light at the center of the detection optical fiber. The optical detection unit selectively detects light only from the center of the region with a radius r below the light emission end of the detection optical fiber. Where r is given by the following formula: Wherein, NA is the numerical aperture of the optical fiber used for detection. c is the core diameter of the optical fiber used for detection. p is the interval between the plurality of capillaries. D out is the outer diameter of the capillary tube, d is the distance from the surface of the capillary to the light incident end of the corresponding detection optical fiber.

2. The capillary electrophoresis apparatus according to claim 1, characterized in that, The light detection unit includes at least a light detector and a selective light-blocking element.

3. The capillary electrophoresis apparatus according to claim 1, characterized in that, The optical detection unit includes at least a photodetector and an optical fiber for connection.

4. The capillary electrophoresis apparatus according to claim 1, characterized in that, The light detection unit includes at least an imaging element and a signal processing unit. The signal processing unit selectively processes the light from the center of the detection optical fiber in the light detected by the imaging element.

5. The capillary electrophoresis apparatus according to claim 2, characterized in that, The light detection unit further includes an imaging optical system that images light emitted from the light-emitting end of the detection optical fiber at the position of the selective light-shielding element.

6. The capillary electrophoresis apparatus according to claim 3, characterized in that, The optical detection unit further includes an imaging optical system that images light emitted from the light-emitting end of the detection optical fiber at the incident end of the connecting optical fiber.

7. The capillary electrophoresis apparatus according to claim 3, characterized in that, The core diameter of the connecting optical fiber is smaller than that of the detection optical fiber.

8. The capillary electrophoresis apparatus according to claim 4, characterized in that, The light detection unit further includes an imaging optical system that images the imaging element with light emitted from the light-emitting end of the detection optical fiber.

9. The capillary electrophoresis apparatus according to claim 1, characterized in that, The optical detection unit is capable of changing at least one of the area and shape of the region of the detection optical fiber that is selectively detected.

Images