Sample Plate Holder for Mass Spectrometer

Abstract

A sample plate holder (6) for a mass spectrometry device comprises: urging members (631 to 633) for pushing one surface of a sample plate toward another surface thereof at three locations that are not positioned on a straight line; and abutting members (612 to 614) which abut said other surface of the sample plate (5) in positions corresponding to the three locations as seen in a plan view. The sample plate holder (6) can suitably be employed in a mass spectrometry device (1) comprising: a laser light emitting unit (13) for emitting laser light onto a sample placed on the sample plate; and a mass spectrometry unit (30) for performing mass spectrometry of ions generated from the sample (S) as a result of the emission of the laser light.

Description

Technical Field

[0001] The present invention relates to a sample plate holder that holds a sample plate used in a mass spectrometer that irradiates a sample with a laser beam and mass-analyzes ions generated from the sample.

Background Art

[0002] In order to measure the distribution of a target substance in a sample, imaging mass spectrometry using a mass spectrometer equipped with MALDI has been performed (for example, Patent Document 1). MALDI is an ion source that ionizes a sample by the Matrix-Assisted Laser Desorption / Ionization method.

[0003] In imaging mass spectrometry using MALDI, by performing a pretreatment of applying a matrix substance, which is a substance that is easily ionized, to the surface of the sample placed on the sample plate, microcrystals of the matrix substance incorporating the molecules of the sample are formed on the surface of the sample. When the sample plate on which the pretreated sample is placed is set at a predetermined position of MALDI and the sample surface is irradiated with a laser beam, the microcrystals of the matrix substance are heated, and the sample molecules are desorbed and ionized. The ions generated from the sample molecules are taken into the mass analysis unit and separated and detected for each mass-to-charge ratio by an appropriate method such as measuring the difference in velocity after acceleration by an electric field, and a mass spectrum with the mass-to-charge ratio on the horizontal axis and the signal intensity on the vertical axis is obtained. By performing such ionization and mass analysis steps at each of a plurality of measurement points two-dimensionally located on the sample surface, a mass spectrum of each measurement point is obtained. By associating (mapping) the intensity of the mass peak corresponding to the target substance on the mass spectrum acquired at each measurement point with each measurement point, an image showing the distribution of the target substance on the sample surface can be obtained.

[0004] In imaging mass spectrometry, in order to irradiate each measurement point with a laser beam having an energy density at which the ionization efficiency of the sample is maximized, the laser beam condensed by a condensing optical system such as a lens or a concave mirror is irradiated. Therefore, if the height of the sample plate deviates from a predetermined position, the energy density of the laser beam irradiated on the sample surface decreases, the ionization efficiency deteriorates, and the measurement sensitivity decreases. In addition, the irradiation spot diameter of the laser beam irradiated on the sample surface increases, and the spatial resolution of the mass distribution image decreases. Therefore, in MALDI, it is necessary to fix the sample plate at a predetermined position and height.

[0005] A sample plate holder is used to fix the sample plate at a predetermined position and height in MALDI. There are various forms of sample plate holders. Non-Patent Document 1 describes a sample plate holder that pushes up the sample plate upward by push pins located below the centers of both short sides of a rectangular sample plate and makes both ends on the short side of the upper surface of the sample plate abut against contact surfaces provided on the sample plate holder to fix the sample plate. Non-Patent Document 2 describes a sample plate holder that inserts extension portions provided so as to extend outward along both long sides of a rectangular sample plate into insertion slots provided in MALDI and pushes up the center of the lower surface of the sample plate with a compression spring to fix the sample plate. Non-Patent Document 3 describes a sample plate holder that pushes up the centers of the lower surfaces of both short sides of a rectangular sample plate upward with compression springs and makes the upper surface of the sample plate abut against overhanging edges provided above it to hold the sample plate.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007] [Non-Patent Document 1] "rapifleXR MALDI TissuetyperR", [online], Bruker Corporation, [searched on July 6, 2022], Internet <URL:https: / / www.bruker.com / ja / products-and-solutions / mass-spectrometry / maldi-tof / rapiflex-maldi-tissuetyper.html> [Non-Patent Document 2] "Desktop Linear Dedicated Machine MALDI-8020", [online], Shimadzu Corporation, [searched on July 6, 2022], Internet <URL:https: / / www.an.shimadzu.co.jp / ms / maldi8020 / index.htm> [Non-Patent Document 3] "Imaging Mass Microscope iMScope QT", [online], Shimadzu Corporation, [searched on July 6, 2022], Internet <URL:https: / / www.an.shimadzu.co.jp / bio / imscope_qt / index.htm> [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] In the sample plate holders of Non-Patent Documents 1 and 2, the point (position) where the sample plate is pushed up from below by a push pin or a pressing spring and the point (position) where the upper surface of the sample plate abuts against the sample plate holder are at different positions in a plan view. In these sample plate holders, since the position where force is applied to the sample plate is different between the lower and upper sides, distortion occurs in the sample plate. For the sample plate, for example, a glass surface coated with a conductive film is used and has a thickness of about 1 mm, but even so, distortion of about several tens of μm in the height direction may occur due to such force.

[0009] In imaging mass spectrometry, in many cases, since a laser beam is irradiated obliquely with respect to the surface of a sample plate, if there is distortion in the sample plate, the laser beam is irradiated at a position deviated from the original measurement point. When the position of the measurement point is shifted, even if an image showing the distribution of the target substance on the sample surface is created from the mass spectrometry data obtained at each measurement point, an image showing the correct distribution of the target substance cannot be obtained. In addition, when distortion occurs in the height direction of the sample plate, the height of the sample placed on its surface also shifts, and as described above, the measurement sensitivity decreases or the spatial resolution deteriorates.

[0010] Further, in vacuum MALDI-TOF (a device that houses both MALDI and TOF in a vacuum chamber), since the ions generated by MALDI are directly introduced into the flight space, the deviation in the height of the sample surface is directly connected to the deviation in the flight distance, and as a result, the mass accuracy in mass spectrometry decreases. Furthermore, in a mass spectrometer equipped with atmospheric pressure MALDI, in order to maintain a high vacuum in the vacuum chamber where the mass analysis unit is provided, the diameter of the ion intake port is minimized (for example, about several millimeters). When the position of the measurement point is shifted, the amount of ions taken into the ion intake port decreases and the measurement sensitivity decreases.

[0011] In the sample plate holder of Non-Patent Document 3, if there is slight distortion on the lower surface of the protruding piece due to manufacturing tolerances of the sample plate holder, or if the lower surfaces of the two protruding pieces are non-parallel, the upper surface of the sample plate and the lower surface of the protruding piece come into contact locally at points. If the point where the sample plate is pushed up from below by the pressing spring and the point where the upper surface of the sample plate and the lower surface of the protruding piece come into contact are at different positions in plan view, similar to the sample plates of Non-Patent Documents 1 and 2, distortion occurs in the sample plate, and as a result, the same problems as described above occur.

[0012] The problem to be solved by the present invention is to provide a sample plate holder for a mass spectrometer that can hold the sample plate without causing distortion.

Means for Solving the Problem

[0013] The sample plate holder for a mass spectrometer according to the present invention, which is made to solve the above problems, has a biasing member that presses one surface of the sample plate at three positions not located on a straight line, and a contact member that contacts the other surface of the sample plate at positions corresponding to the three positions in a plan view. It is provided with.

Effect of the Invention

[0014] In the sample plate holder according to the present invention, at three positions (three points) not located on a straight line, the biasing member presses the other surface (for example, the lower surface) of the sample plate and contacts the contact member at positions corresponding to the three positions in a plan view. In the sample plate holder according to the present invention, since the force point that presses the sample plate and the fulcrum that contacts and supports the sample plate are in positions corresponding to each other in a plan view, the sample plate does not get distorted. Also, since a single plane is defined by three points not located on a straight line, by using the sample plate holder according to the present invention, the sample plate can be held so that the surface of the sample plate is always at the same position and height.

Brief Description of the Drawings

[0015]

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Embodiments for Carrying Out the Invention

[0016] Embodiments of the sample plate holder for a mass spectrometer according to the present invention will be described below with reference to the drawings.

[0017] FIG. 1 is a diagram showing the main configuration of a mass spectrometer in which the sample plate holders of the embodiments described below are used. This mass spectrometer 1 is a MALDI-TOF MS. That is, an ion source (vacuum MALDI in this embodiment) that ionizes a sample by the Matrix-Assisted Laser Desorption / Ionization method, and a time-of-flight mass spectrometry unit that flies the ions generated by the ion source, separates them according to the mass-to-charge ratio, and detects them.

[0018] The mass spectrometer 1 of this embodiment includes a stage 12 on which a sample plate holder 6 holding a sample plate 5 on which a sample S is placed is set, a laser light irradiation unit 13 that emits laser light, a concave mirror 14 that condenses the laser light emitted from the laser light irradiation unit 13 onto the sample S, and an imaging unit 17 that images the sample S. Further, a stage drive unit 18 including a motor or the like that moves the stage 12 between the imaging position (left side in FIG. 1) and the measurement position (right side in FIG. 1) of the sample S and moves the stage in the horizontal direction (the two-axis direction of the X-axis and Y-axis in FIG. 1) at the measurement position is provided.

[0019] Also, directly above the measurement position of the stage 12, an acceleration electrode 21 that draws out and accelerates ions generated from the sample S placed on the sample plate holder 6 upward, and an ion lens 22 as an ion transport optical system that transports the ions accelerated by the acceleration electrode 21 to a mass spectrometry unit 30 described later are provided.

[0020] The mass spectrometry unit 30 has a reflectron-type configuration including a flight tube 31 which is a cylindrical electrode that defines a free flight space where ions fly freely without being affected by an electric field, a reflectron 32 which is a ring-shaped electrode that causes ions to fly back by the action of a direct current electric field, and a back plate 33 which is a disk-shaped electrode. An ion detector 34 is arranged at the end of the flight path of the ions defined by these electrodes. The detection signal by the ion detector 34 is converted into digital data by an analog-to-digital converter (not shown) and input to a control and processing unit 40.

[0021] Each of the above components is housed within the chamber 10. The interior of the chamber 10 is partitioned by a gate valve 19 located at a lower position shown by a dashed line in FIG. 1 into an atmospheric pressure space including the imaging position of the sample S and a vacuum space including the measurement position and the mass spectrometry unit 30. When moving the stage 12 between the imaging position and the measurement position, the gate valve 19 is opened (moved to the upper position shown by a solid line in FIG. 1). The vacuum space is evacuated by a vacuum pump (not shown). Here, for ease of explanation, the interior of the chamber 10 is partitioned into an atmospheric pressure space and a vacuum space, but in addition to the atmospheric pressure space for imaging the sample S and the high vacuum space for mass spectrometry of ions, one or more intermediate vacuum degree spaces can be appropriately provided between the two.

[0022] The control and processing unit 40 includes a storage unit 41. In the storage unit 41, a compound database in which information such as measurement conditions and analysis parameters of various compounds is recorded, information for converting the flight time of ions into the mass-to-charge ratio of ions (mass conversion information), etc. are stored. Further, the control and processing unit 40 has functional blocks such as a measurement control unit 42 that controls the operations of the above components to execute measurement, and an analysis processing unit 43 that analyzes the data obtained by the measurement. The control and processing unit 40 is constituted by, for example, a general computer, and these functional blocks are realized by a processor executing dedicated software installed in advance. An input unit 44 for the user to input appropriate information and a display unit 45 for displaying various information are connected to the control and processing unit 40.

[0023] Next, the procedure for imaging mass spectrometry of a sample in the mass spectrometer 1 of this embodiment will be described. The measurement of the sample for imaging mass spectrometry is executed by the control of each component by the above measurement control unit 42 (application of voltage from a power source (not shown) to each electrode, etc.), and the analysis of the data acquired by the measurement is executed by the analysis processing unit 43.

[0024] First, the user places the sample S to be analyzed on the sample plate 5 and applies a matrix substance, which is a substance that is easy to ionize, to the surface thereof. As a result, microcrystals of the matrix substance incorporating the molecules of the sample S are formed on the surface of the sample S.

[0025] Next, the sample plate 5 on which the sample S after the above treatment is placed is held by the sample plate holder 6 and set on the stage 12. Then, the stage 12 is positioned at the imaging position of the sample S, and the surface of the sample S on the sample plate holder 6 is imaged. The image acquired by the imaging unit 17 is displayed on the screen of the display unit 45. The user checks this screen to set a region of interest (ROI) for performing imaging mass spectrometry and sets a plurality of measurement points two-dimensionally (for example, in a grid pattern) within the region of interest.

[0026] After setting a plurality of measurement points within the region of interest, when the user instructs the start of measurement, the gate valve 19 is opened, and the stage drive unit 18 moves the stage 12 from the imaging position of the sample S to the measurement position. When the stage moves to the measurement position, a predetermined voltage (including the case of being grounded) is applied to the sample plate 5 and the sample plate holder 6. As a result, a potential gradient is formed between the sample plate 5 and the sample plate holder 6 and the acceleration electrode 21. Then, the stage drive unit 18 moves the stage 12 so that the first measurement point is located at the irradiation position of the laser beam. Then, the laser beam is irradiated from the laser beam irradiation unit 13, reflected and condensed by the concave mirror 14, and the laser beam condensed on the first measurement point is irradiated.

[0027] When the condensed laser beam is irradiated, the microcrystals of the matrix substance are heated at the measurement point of the sample S, and the sample molecules are desorbed and ionized. The ions generated from the measurement point of the sample S are drawn upward and accelerated by the potential gradient between the sample plate 5 and the acceleration electrode 21.

[0028] Ions drawn above the sample S are transported to the mass spectrometry unit 30 while being converged along the central axis of the flight direction (ion optical axis C) by the ion lens 22. The ions that have entered the mass spectrometry unit 30 travel straight through the free flight space surrounded by the flight tube 31, and then are reflected back in the space surrounded by the reflectron 32 and enter the ion detector 34. The ion detector 34 sequentially outputs a signal corresponding to the amount of incident ions. The signal output from the ion detector 34 is digitally converted and sent to the control and processing unit 40.

[0029] At the first measurement point, when a series of measurements from the irradiation of the laser beam to the detection of ions is completed, the stage drive unit 18 moves the stage 12 so that the next measurement point is located at the irradiation position of the laser beam. Then, the laser beam is irradiated from the laser beam irradiation unit 13, reflected and condensed by the concave mirror 14, and the laser beam condensed at the second measurement point is irradiated. Thereafter, mass spectrum data of the second measurement point is obtained by the same processing as described above. When the series of measurements are completed for all the measurement points, the measurement operation is terminated.

[0030] The control and processing unit 40 converts the flight time of ions into the mass-to-charge ratio of ions based on the mass conversion information stored in the storage unit 41, and generates mass spectrum data associating the measurement intensity with the mass-to-charge ratio of ions. The generated mass spectrum data is stored in the storage unit 41 in association with the position information of the measurement points.

[0031] After the mass spectrum data of each measurement point is created and stored, for example, when the user makes an input specifying the mass-to-charge ratio of ions specific to the target substance, the analysis processing unit 43 extracts information on the measurement intensity of ions with the mass-to-charge ratio from the mass spectrum data obtained for each measurement point. Then, image data is generated in which the measurement intensity of the ions is visibly displayed (for example, colored or shaded according to the measurement intensity) at the position of each measurement point, and the image is displayed on the screen of the display unit 45. The user can know the distribution of the target substance in the sample S by checking the image displayed on the screen of the display unit 45.

[0032] Next, the sample plate holder 6 of the first embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 is an external view of the sample plate holder 6 holding the sample plate 5 (the left view is from above, and the right view is from below), FIG. 3 is a view of the upper frame member 61 from below, and FIG. 4 is a cross-sectional view of the sample plate holder 6 taken along the line A-A'. In each of the figures used in the following description, for the sake of clarity in showing the relationship and shape of each member, the members are illustrated at scales different from the actual ones as appropriate, or the shapes are exaggerated. Note that the "upper and lower" etc. in the present specification are described for convenience in the description and do not limit the orientation when using the sample plate holder.

[0033] The sample plate holder 6 is roughly composed of an upper frame member 61 and a lower frame member 62, and the two are fixed by screws 64 and 65.

[0034] The upper frame member 61 is generally in a substantially rectangular shape and has a frame member with an opening from the center to one long side. On the upper ends of both short sides, there are formed protruding pieces 611 (corresponding to the reinforcing members described later) having a flat upper surface that protrudes inward. The central opening has a size corresponding to the area where the sample S is placed on the sample plate 5.

[0035] On the back surface of the protruding piece 611 on one short side (the first short side) of the upper frame member 61, two contact surfaces are provided. The contact surface is the portion that contacts the upper surface of the sample plate 5 when the sample plate 5 is held, and is formed by protruding portions 612 and 613 (corresponding to the contact members in the present invention) that protrude more toward the back surface side than other parts of the protruding piece 611 (see FIG. 3). Also, on the back surface of the protruding piece 611 on the other short side (the second short side) of the upper frame member 61, one contact surface is provided. This contact surface is also the portion that contacts the upper surface of the sample plate 5 when the sample plate 5 is held, and is formed by a protruding portion 614 (corresponding to the contact member in the present invention) that protrudes more toward the back surface side than other parts of the protruding piece 611.

[0036] The lower frame member 62 is a substantially rectangular member with an outer shape slightly larger than that of the upper frame member 61 and an opening in the center. On one short side thereof, a gripping portion 621 for gripping the sample plate holder 6 is provided when transporting the sample plate holder 6 or the like.

[0037] On one short side (the first short side) of the lower frame member 62, pressing springs 631 and 632 (corresponding to the biasing members in the present invention) for biasing the sample plate 5 upward are attached at positions below the respective two protruding portions 612 and 613 in a plan view. Also, on the other short side (the second short side) of the lower frame member 62, a pressing spring 633 (corresponding to the biasing member in the present invention) for biasing the sample plate 5 upward is attached at a position below the protruding portion 614 in a plan view. The pressing springs 631, 632, and 633 in this embodiment are all leaf springs having a bent cross section (see FIG. 4), and one end is fixed to the lower surface of the lower frame member 62 with screws 65 so that the bent portion faces the upper frame member 61 side.

[0038] When holding the sample plate 5 with the sample plate holder 6, the sample plate 5 is inserted between the upper frame member 61 and the lower frame member 62 from the side where the long side portion of the upper frame member 61 is open. The inserted sample plate 5 is pushed upward by the pressing springs 631, 632, and 633 at three locations (three points) toward the upper frame member 61 side. The upper surface of the sample plate 5 pushed upward toward the upper frame member 61 side is held in contact with the protruding portions 612, 613, and 614 at three locations (three points).

[0039] When performing imaging mass spectrometry as in this embodiment, in order to irradiate each measurement point of the sample S with a laser beam having an energy density that maximizes the amount of ions generated from each measurement point of the sample S (maximizes the ionization efficiency), the laser beam is focused and irradiated. Therefore, if the height of the sample plate 5 deviates from a predetermined position, the energy density of the laser beam irradiated on the surface of the sample S decreases, the ionization efficiency deteriorates, and the measurement sensitivity decreases. In addition, the irradiation spot diameter of the laser beam irradiated on the surface of the sample S increases, and the spatial resolution of the mass distribution image decreases. Therefore, in MALDI, it is necessary to fix the sample plate at a predetermined position and height.

[0040] However, in a conventionally used sample plate holder, since the position where a force is applied from above and the position where a force is applied from below to the sample plate are different, the sample plate may be held in a distorted state. As the sample plate, for example, a glass surface coated with a conductive film is used. Although the sample plate 5 has a thickness of about 1 mm, in a conventional sample plate holder, such a force may cause a distortion with a height of about several tens of μm.

[0041] Particularly in MALDI having a configuration in which a laser beam is irradiated obliquely from above the surface of the sample plate 5 as in this embodiment, if the sample plate 5 is distorted, the laser beam is irradiated to a position deviated from the original measurement point. When the position of the measurement point is shifted, even if an image showing the distribution of the target substance on the surface of the sample S is created from the mass spectrometry data obtained at each measurement point, an image showing the correct distribution of the target substance cannot be obtained. In addition, when a distortion occurs in the height direction of the sample plate 5, the height of the sample S placed on its surface also shifts, and as described above, the measurement sensitivity decreases and the spatial resolution deteriorates.

[0042] Also, in vacuum MALDI-TOF such as in this embodiment, since the ions generated by MALDI are directly introduced into the flight space, the deviation in the height of the surface of the sample S directly leads to the deviation in the flight distance. As a result, the mass accuracy in mass spectrometry decreases. This problem also occurs similarly in mass spectrometry without imaging (for example, mass spectrometry in which a sample mixed with a matrix substance is placed on each of a plurality of wells provided in a sample plate and measured).

[0043] This embodiment is a mass spectrometer equipped with vacuum MALDI. In a mass spectrometer equipped with atmospheric pressure MALDI, in order to maintain a high vacuum in the vacuum chamber, the diameter of the aperture that partitions the atmospheric pressure space where the sample is irradiated with laser light and the vacuum space where the ions generated from the sample are mass-analyzed is minimized (for example, about several millimeters). Therefore, if the position of the measurement point shifts, the amount of ions passing through the aperture decreases and the measurement sensitivity decreases.

[0044] On the other hand, in the sample plate holder 6 of the first embodiment, the pressing springs 631, 632, and 633 are provided at positions corresponding to the protruding portions 612, 613, and 614 (positions below the protruding portions 612, 613, and 614 in plan view). When the sample plate 5 is held using the sample plate holder 6, since forces are applied from the upper and lower sides of the sample plate 5 at the same position, the sample plate 5 can be held by the sample plate holder 6 without causing distortion in the sample plate 5. Also, since a single plane is defined by three points that are not located on a straight line, by using the sample plate holder 6, the sample plate 5 can be held by the sample plate holder 6 so that the surface of the sample plate 5 is always at the same position and height.

[0045] Also, in the sample plate holder 6 of the first embodiment, the sample plate 5 is held by the sample plate holder 6 at two points along one short side of the sample plate 5 and one point along the other short side. More generally speaking, at least one contact portion (the portion where the sample plate 5 is held by the sample plate holder 6) is provided in each of the two regions divided by a plane passing through the center of gravity of the sample plate 5 and perpendicular to the surface of the sample plate 5. Therefore, the sample plate 5 can be held more stably than when only three contact portions are provided in one of the two regions.

[0046] The sample plate holder 6 of the first embodiment is designed based on the technical idea of holding the sample plate 5 from above and below at three points not on a straight line as described above, and a sample plate holder along this technical idea can be configured without necessarily providing the overhanging piece 611.

[0047] Fig. 5 shows the configuration of the upper frame member 71 of the sample plate holder 7 of the modified example. Since the lower frame member of the sample plate holder 7 of the modified example has the same configuration as the lower frame member 62 of the above embodiment, the description thereof is omitted.

[0048] As shown in Fig. 5, the upper frame member 71 is provided with only the members corresponding to the overhanging portions 612, 613, and 614 without providing the portion corresponding to the overhanging piece 611 in the above embodiment. By using the sample plate holder 7 having such a configuration, the sample plate 5 can be held without causing distortion.

[0049] However, when a voltage is applied to the sample plate 5 and the sample plate holder 6 to form a potential gradient between the acceleration electrode 21 (in the case of vacuum MALDI) or the partition wall (in the case of atmospheric pressure MALDI), if the step between the upper surface of the sample plate 5 and the upper surface of the sample plate holder 6 becomes large, electric field disturbance may occur at that portion. Therefore, it is necessary to make the overhanging piece 611 of the sample plate holder 6 as thin as possible. In the sample plate holder 6 of the above embodiment, the thickness of the overhanging piece 611 is 0.5 mm, and the thicknesses of the overhanging portions 612, 613, and 614 are 0.1 mm. That is, the step between the upper surface of the sample plate 5 and the upper surface of the sample plate holder 6 is suppressed to 0.6 mm.

[0050] In the sample plate holder 7 of the modification, in order to reduce the step between the upper surface of the sample plate 5 and the upper surface of the sample plate holder 6 in this way by thinning the overhanging portions 612, 613, and 614, the strength of each of the overhanging portions 612, 613, and 614 may be insufficient, and there is a possibility of deformation or breakage during repeated use. Further, since there is a step between the portion where the overhanging portions 612, 613, and 614 are provided and the portion where they are not provided on the upper surface of the upper frame member 71 of the sample plate holder 7, electric field disturbance may also occur thereby. Considering these points, it is preferable to provide an overhanging piece 611 having a flat upper surface as in the sample plate holder 6 of the above embodiment, and to form the overhanging portions 612, 613, and 614 integrally with the overhanging piece 611.

[0051] When the sample plate 5 is held using the above sample plate holders 6 and 7, the distortion (warping and twisting) of the sample plate 5 can be suppressed as compared with the conventional ones. However, when the present inventor further studied, a configuration that can more reliably suppress the distortion of the sample plate 5 was found. Hereinafter, the sample plate holder 8 will be described with reference to FIGS. 6 to 12. In the following description, the same reference numerals are given to the same components as those of the sample plate holder 6, and the description will be omitted as appropriate.

[0052] This examination was carried out using the sample plate holder 8 of the second embodiment. The sample plate holder 8 of the second embodiment will be described with reference to FIGS. 6 to 8. The upper part of FIG. 6 shows a state of the pressing springs 631 and 832 as viewed from the upper surface side of the sample plate holder 8, and the lower part of FIG. 6 shows a view of the pressing springs 631 and 832 as viewed from the outside of the short side of the sample plate holder 8. Plate-shaped fixing portions 834 for fixing the pressing springs 631 and 832 are provided on the base sides of the pressing springs 631 and 832, respectively, and openings 8341 for inserting the screws 65 are formed in the fixing portions 834. As shown in these figures, the pressing spring 631 is a linear leaf spring, while the pressing spring 832 includes a linear portion 8321 and an extending portion 8322 extending from the linear portion 8321 toward the side of the pressing spring 631, and the extending portion 8322 abuts against the sample plate 5. The dashed line in FIG. 6 indicates the position where the pressing springs 631 and 832 abut against the protruding portions 612 and 613.

[0053] FIG. 7 is an enlarged view of the contact portions of the pressing springs 832 and 633 of the sample plate holder 8 with the sample plate 5, and the contact portions of the sample plate 5 with the protruding portions 613 and 614.

[0054] In the sample plate holder 8, a wall portion 86 (corresponding to the side member in the present invention) stands upright from the protruding piece 611 toward the lower frame member 62 outside the side surface (the surface on the side where the pressing springs 631 and 832 are located) on one short side of the sample plate 5, and outside the side surface (the surface on the side where the pressing spring 633 is located) on the other short side, a leaf spring 87 that presses the side surface on the other short side of the sample plate 5 toward the wall portion 86 is arranged. In the sample plate holder 8, the protruding piece 611 and the wall portion 86 are formed as one member, but they may be formed as separate members. Thus, even when the length of the sample plate 5 in the long side direction differs for each manufacturer, both side surfaces of the sample plate 5 can be stably held by sandwiching them between the wall portion 86 and the leaf spring 87.

[0055] Even in the case of the sample plate holder 8, the pressing springs 631, 832 and the pressing spring 633 are respectively attached to the vicinity of both ends of the long side of the lower frame member 62 of the sample plate holder 8 by two screws 65. At this time, due to the machining error during the manufacturing of the sample plate holder 8, the surface accuracy of the spring attachment portion of the lower frame member 62 may deteriorate. Then, the pressing springs 631, 832 and the pressing spring 633 may be attached in an inclined manner. If the pressing springs 631, 832, 633 are attached so as to incline away from the sample plate 5 toward the inside, the outer ends of the pressing springs 631, 832, 633 come into contact with the sample plate 5. On the other hand, if the pressing springs 631, 832, 633 are attached so as to incline closer to the sample plate 5 toward the inside, the inner ends of the pressing springs 631, 832, 633 come into contact with the sample plate 5.

[0056] Also, regarding the protruding portions 612 to 614, due to the machining error during the manufacturing of the sample plate holder 6, the contact surfaces (the surfaces that come into contact with the sample plate 5) of the protruding portions 612 to 614 may be inclined. If the contact surfaces of the protruding portions 612 to 614 are inclined so as to move away from the surface of the sample plate 5 toward the inside, the outer ends (base portions) of the protruding portions 612 to 614 come into contact with the sample plate 5. On the other hand, if the protruding portions 612 to 614 are inclined so as to approach the sample plate 5 toward the inside, the inner ends (tip portions) of the protruding portions 612 to 614 come into contact with the sample plate 5.

[0057] Then, a state as shown in FIG. 8 may occur. FIG. 8 corresponds to the B-B' cross-section in FIG. 2 of the sample plate holder 8 holding the sample plate 5. Note that in FIG. 8, the up and down directions are reversed, and in FIG. 8, the lower surface of the sample plate holder 8 is located upward. The upper part of FIG. 8 shows a state where the outer ends of the pressing springs 832 and 633 are in contact with the sample plate 5, and the tip ends of the protruding portions 613 and 614 are in contact with the sample plate 5. When the sample plate 5 is held in this state, there is a slight deviation between the position where the pressing springs 832 and 633 press the sample plate 5 and the position where the sample plate 5 is supported by the protruding portions 613 and 614. As a result, the sample plate 5 warps downward.

[0058] The lower part of FIG. 8 shows a state where the inner ends of the pressing springs 832 and 633 are in contact with the sample plate 5, and the bases of the protruding portions 613 and 614 are in contact with the sample plate 5. Even when the sample plate 5 is held in this state, there is a slight deviation between the position where the pressing springs 832 and 633 press the sample plate 5 and the position where the sample plate 5 is supported by the protruding portions 613 and 614. As a result, the sample plate 5 warps upward.

[0059] In this way, in order to more reliably avoid warping of the sample plate 5 due to machining errors during manufacturing, further improvements were made to configure the sample plate holder 9 of the third embodiment.

[0060] The configuration of the sample plate holder 9 of the third embodiment is shown in FIG. 9. The upper part of FIG. 9 is a view of the sample plate holder 9 seen from below, and the lower part of FIG. 9 is a cross-sectional view showing the structure of the spring attachment portion. In the following description, for components common to the sample plate holders 6 and 8, the same reference numerals are given and detailed descriptions are omitted.

[0061] In the sample plate holder 9, the spring mounting surface 9211 of the lower frame member 92 is inclined from the horizontal. More specifically, it is inclined 5 degrees from the horizontal so as to become thicker toward the inside of the sample plate holder 9. Further, a screw hole is formed perpendicular to this inclined surface. Therefore, when the pressing springs 631, 832, and 633 are attached, they are also attached in a state inclined 5 degrees with respect to the horizontal plane.

[0062] In addition, the pressing springs 832 and 633 are also attached so as to be inclined in the horizontal direction (the direction parallel to the surface of the sample plate 5) so as to open outward as they move away from the screw 65. This is to avoid interference with the wall portion 96 and the leaf spring 97 described later. If the wall portion 96 and the leaf spring 97 are provided at positions where they do not interfere with the pressing springs 832 and 633, the pressing springs 832 and 633 do not have to be inclined in the horizontal direction (they may be arranged parallel to the short side of the sample plate 5).

[0063] The upper part of FIG. 10 is a perspective view of the sample plate holder 9 as viewed from the lower surface side (however, the lower frame member 62, the pressing springs 631, 832, 633, and the screws 64 and 65 are not shown). The lower part of FIG. 10 is an enlarged cross-sectional view of the vicinity of both ends on the short side of the sample plate 5 (a view corresponding to the C-C' cross-section in the upper part of FIG. 10). Also in the sample plate holder 9, similar to the sample plate holder 8, a wall portion 96 (corresponding to the side member in the present invention) stands upright from the protruding piece 611 toward the lower frame member 62 outside the side surface on one short side of the sample plate 5 (the side surface where the pressing springs 631 and 832 are located), and on the outside of the side surface on the other short side of the sample plate 5 (the side surface where the pressing spring 633 is located), a leaf spring 97 that presses the side surface on the other short side of the sample plate 5 toward the wall portion 96 is arranged. Also in the sample plate 9, the protruding piece 611 and the wall portion 96 are formed of one member, but they may be formed of separate members. Thus, similar to the sample plate holder 8, the side surfaces of the sample plate 5 having slightly different sizes (the length on the long side) for each manufacturer can be stably held by sandwiching them between the wall portion 96 and the leaf spring 97.

[0064] However, in the sample plate holder 9, as shown in the lower part of FIG. 10, the wall portion 96 is formed lower than the thickness of the sample plate 5, and a gap is provided between the leaf spring 97 and the sample plate 5 at the position of the C-C' cross section in FIG. 10. That is, the position where the leaf spring 97 presses the sample plate 5 is shifted from the position where the leaf springs 633 press the sample plate. By forming it in this way, the leaf springs 631, 832, and 633 can contact the ridge line of the sample plate 5 (the edge on the short side of the surface of the sample plate 5, the corner in the C-C' cross section) without interfering with the wall portion 96 and the leaf spring 97. As a result, the positional relationship between the force point and the fulcrum in the sample plate 5 is precisely matched in plan view, and the state shown in the lower part of FIG. 8 is avoided. When the inclination angles of the pressing leaf springs 631, 832, and 633 were variously changed, when the inclination angle was less than 1 degree, the pressing leaf springs 631, 832, and 633 sometimes did not contact the ridge line of the sample plate 5 due to a large machining error on the spring mounting surface of the lower frame member 62. Therefore, it is preferable that the pressing leaf springs 631, 832, and 633 are inclined by 1 degree or more with respect to the surface of the sample plate 5. On the other hand, if the pressing leaf springs 631, 832, and 633 are inclined excessively, the force that presses the sample plate 5 from below toward the overhanging portions 912 to 914, which is the original function, becomes weak. Considering this point, the inclination angle of the pressing leaf springs 631, 832, and 633 is preferably 60 degrees or less.

[0065] Also, in the sample plate holder 9, the lengths (overhang lengths) of the overhang portions 912 to 914 are made smaller than those of the sample plate holder 6 of the first embodiment. Specifically, in the sample plate holder 6, the lengths of the overhang portions 612 and 613 were 3.3 mm, and the length of the overhang portion 614 was 2.8 mm, whereas in the sample plate holder 9, the lengths of the overhang portions 912 and 913 are 1.5 mm, and the length of the overhang portion 914 is 1.0 mm. Here, the length of the overhang portion refers to the length of the portion that overlaps the sample plate 5 in a plan view among the total lengths of the overhang portions. As can be seen from FIG. 8, depending on the surface accuracy of the overhang portions 912 to 914, the position of the fulcrum on the sample plate 5 changes by up to the lengths of the overhang portions 912 to 914. In the sample plate holder 9, by shortening the overhang portions 912 to 914, even if the contact surfaces of the overhang portions 912 to 914 are inclined due to machining errors during manufacturing, the displacement of the fulcrum position can be suppressed to a small value, and thereby, the displacement of the force point and the fulcrum in a plan view can be suppressed to a small value. Therefore, the distortion of the sample plate 5 can be made smaller than that of the sample plate holder 6. As described above, in the sample plate holder 6, the lengths of the overhang portions 612 and 613 were 3.3 mm, but according to the study by the present inventor, by setting the lengths of the overhang portions 912 to 914 to 3.0 mm or less, even when the overhang portions 912 to 914 are inclined, the distortion of the sample plate 5 can be suppressed.

[0066] The overhang portions 912 to 914 may be inclined surfaces. Specifically, the overhang portions 912 to 914 are inclined in a direction away from the surface of the sample plate 5 as going from the outside to the inside. Thereby, as schematically shown in FIG. 11, in addition to the pressing springs 832 and 633, the overhang portions 912 to 914 also come into contact with the ridge line of the sample plate 5 (the edge portion on the short side of the surface of the sample plate 5. The corner portion in the C-C' cross section). By adopting such a configuration, the positions of the force point and the fulcrum on the sample plate 5 can more precisely coincide in a plan view, and the occurrence of distortion in the sample plate 5 can be more reliably suppressed.

[0067] Alternatively, without providing the protruding portions 912 to 914, the protruding piece 911 may be inclined in a direction away from the surface of the sample plate 5 as it goes from the outside to the inside, and the ridge line of the sample plate 5 and the protruding piece 911 may be brought into linear contact. However, in this case, it is required that the protruding piece 911 is a flat inclined surface as a whole (the inclination angle is uniform). Therefore, as described above, it is preferable to adopt a configuration in which the protruding portions 912 to 914 provided on the protruding piece 911 are inclined surfaces.

[0068] Furthermore, in the sample plate holder 9, as shown in FIG. 12, depressions 9121, 9131, and 9141 are provided on the base side of the protruding portions 912, 913, and 914. In addition, V-shaped grooves 981 to 983 are formed in portions of the protruding portions 912 to 914 that are located on the side where the sample plate 5 is inserted. As a result, the ends of the protruding portions 912 to 914 on the side where the sample plate 5 is inserted are tapered. In the sample plate holder 6 of the first embodiment, flat protruding portions 612 to 614 are provided on the protruding piece 611. In addition, the protruding portions 612 to 614 are not completely rectangular but have a shape that widens toward the base side (FIG. 3). Therefore, a step is generated at the boundary between the protruding piece 611 and the protruding portions 612 to 614, and when the sample plate 5 is inserted, the sample plate 5 may get caught on this step and the work may be time-consuming.

[0069] On the other hand, in the sample plate holder 9 of the third embodiment, the boundary between the protruding piece 911 and the protruding portions 912 to 914 is tapered, and since there is no widening at the base of the protruding portions 912 to 914, the sample plate 5 can be inserted smoothly. In FIG. 12, the V-shaped grooves 981 to 983 are formed, but a tapered portion may be provided by other methods. However, since the thickness of the protruding portions 912 to 914 is very thin, 0.1 mm as in the sample plate holder 6, it is not easy to perform processing to form an inclined surface on this. As shown in FIG. 12, by forming V-shaped grooves at the ends of the protruding portions 612 to 614, a tapered portion can be easily provided.

[0070] The above embodiments are merely examples and can be appropriately modified in accordance with the gist of the present invention.

[0071] In the above, the mass spectrometer 1 equipped with vacuum MALDI is used. However, in a mass spectrometer equipped with atmospheric pressure MALDI or other ion sources that irradiate a sample with laser light when ionizing the sample, the sample plate holders 6 to 9 of the above examples and modified examples can also be preferably used. For example, in a mass spectrometer equipped with an ion source that generates ions from a sample by laser desorption / ionization (LDI), electrospray laser desorption ionization (ELDI), or a laser ablation inductively coupled plasma mass spectrometer (LA-ICP MS), the sample plate holders 6 to 9 of the above examples and modified examples can also be preferably used.

[0072] In the above embodiment, the mass spectrometer 1 having a reflectron TOF type mass analysis unit is used. However, regardless of the configuration of the mass separation unit such as linear TOF type, ion trap type, quadrupole type, etc., the sample plate holder 6 of the above embodiment and modified examples can be preferably used.

[0073] Also, in the sample plate holders 6 to 9 of the above embodiments and modified examples, the protruding portions 612 to 614, 914 to 916 and the pressing springs 631, 632, 633, 832 used as the contact members and biasing members are merely one configuration example, and can be replaced with appropriate members that function as the contact members and biasing members in the present invention. For example, as the biasing member, a spring or a push pin that biases the sample plate 5 from below each contact portion to the upper frame members 61, 71 can also be used.

[0074] In the sample plate holder 9, the pressing springs 631, 832, and 633 are inclined by inclining the mounting surface 9211 of the screw 65 with respect to the surface of the sample plate 5. However, other methods can also be adopted. For example, as schematically shown in FIG. 13 (a modification of the third embodiment), the mounting surface 9211 of the screw 65 is kept parallel to the surface of the sample plate 5, and a washer 8351 having an inclined surface inclined with respect to the surface of the sample plate 5, a fixing portion 834, and a washer 8352 having an inclined surface inclined on the side opposite to the washer 8351 are sandwiched therebetween and fixed with the screw 65. By doing so, the pressing springs 631, 832, and 633 can also be inclined with respect to the surface of the sample plate 5.

[0075] [Aspect] It is obvious to those skilled in the art that the above-described exemplary embodiments are specific examples of the following aspects.

[0076] (Item 1) A sample plate holder for a mass spectrometer according to one aspect of the present invention includes a biasing member that presses one surface of the sample plate at three positions not located on a straight line, and a contact member that contacts the other surface of the sample plate at positions corresponding to the three positions in a plan view and is provided with.

[0077] In the sample plate holder according to Item 1, at three positions (three points) not located on a straight line, the biasing member presses the other surface (for example, the lower surface) of the sample plate and contacts the contact member at positions corresponding to the three positions in a plan view (typically three positions at the same position). In the sample plate holder according to Item 1, since the force point for pressing the sample plate and the fulcrum for contacting and supporting the sample plate are at the same position in a plan view, no distortion occurs in the sample plate. Further, since a single plane is defined by three points not located on a straight line, by using the sample plate holder according to Item 1, the sample plate can be held so that the surface of the sample plate is always at the same position and height.

[0078] (Item 2) The sample plate holder according to Item 2 is the sample plate holder according to Item 1, wherein the contact member is integrally formed with a reinforcing member having a larger area than the contact member in a plan view.

[0079] (Item 3) The sample plate holder according to Item 3 is the sample plate holder according to Item 2, wherein the sample plate is substantially rectangular, the contact member is integrally formed with a reinforcing member provided along each of both short sides of the sample plate on one surface of the sample plate.

[0080] In the sample plate holder of Item 2, when a predetermined voltage is applied to the sample plate and the sample plate holder, even when suppressing the disturbance of the electric field by reducing the step between the upper surface of the sample plate and the upper surface of the sample plate holder, sufficient strength can be ensured by the reinforcing member. Further, when holding a widely used rectangular sample plate, the sample plate holder of Item 3 can be preferably used.

[0081] (Item 4) The sample plate holder according to Item 4 is the sample plate holder according to any one of Items 1 to 3, wherein at least one of the three locations is located in each of two regions divided by a plane passing through the center of gravity of the sample plate and perpendicular to the surface of the sample plate.

[0082] By using the sample plate holder of Item 4, the sample plate can be stably held as compared with the case where the sample plate is held only in one of the two regions.

[0083] (Item 5) The sample plate holder according to Item 5 is the sample plate holder according to any one of Items 1 to 4, wherein The biasing member abuts against the edge of the sample plate.

[0084] (Item 6) The sample plate holder according to Item 6 is the sample plate holder according to Item 5, wherein the biasing member is three leaf springs, and the three leaf springs are each arranged inclined with respect to the surface of the sample plate so as to move away from the surface of the sample plate from the outside to the inside of the sample plate.

[0085] (Item 7) The sample plate holder according to Item 7 is the sample plate holder according to Item 6, wherein a first leaf spring, which is one of the three leaf springs, is arranged along one side of the sample plate, and second and third leaf springs, which are two of the three leaf springs, are arranged along the side opposite to the one side.

[0086] (Item 8) The sample plate holder according to Item 8 is the sample plate holder according to Item 7, wherein the third leaf spring is arranged inside the sample plate more than the second leaf spring, and has a linear portion and an extension portion extending from the linear portion to the outside of the sample plate.

[0087] In the sample plate holder of Item 5, displacement of the force point position in the sample plate is reduced by the biasing member pressing the edge of the sample plate. As such a configuration, for example, three leaf springs as described in Item 6 can be preferably used. Further, by arranging the three leaf springs described in Item 6 as described in Item 7, the sample plate can be held so as to be pressed from the outside of two opposite sides of the sample plate. Furthermore, by configuring the third leaf spring, which is arranged inside the sample plate more than the other leaf springs, as described in Item 8, not only the first leaf spring and the second leaf spring but also the third leaf spring can be configured to press the edge of the sample plate.

[0088] (Item 9) The sample plate holder according to Item 9 is the sample plate holder according to any one of Items 6 to 8, and further, a first frame member provided with the contact member, a member fixed to the first frame member and having a second frame member to which the three leaf springs are attached and includes the sample plate is held between the first frame member and the second frame member.

[0089] (Item 10) The sample plate holder according to Item 10 is the sample plate holder according to Item 9, and an attachment surface inclined with respect to the surface of the sample plate is provided on the second frame member, and the three leaf springs are attached to the attachment surface.

[0090] (Item 11) The sample plate holder according to Item 11 is the sample plate holder according to Item 9, and an attachment surface parallel to the surface of the sample plate is provided on the second frame member, and the leaf spring is attached to the attachment surface via an inclined member having an inclined surface inclined with respect to the surface.

[0091] As described in Item 9, one aspect of the sample plate holder according to the present invention includes a first frame member provided with a contact member and a second frame member to which three leaf springs are attached, and can hold a sample plate between the first frame member and the second frame member. Then, as described in Item 10, by providing an attachment surface inclined with respect to the surface of the sample plate on the second frame member, or as described in Item 11, by arranging an inclined member having an inclined surface inclined with respect to the surface of the sample plate, the three leaf springs can be attached inclined with respect to the surface of the sample plate.

[0092] (Item 12) The sample plate holder according to Item 12 is the sample plate holder according to any one of Items 9 to 11, Among the contact members, the portion located on the side where the sample plate is inserted is formed in a tapered shape.

[0093] In the sample plate holder according to Item 12, the sample plate can be inserted smoothly.

[0094] (Item 13) The sample plate holder according to Item 13 is the sample plate holder according to Item 12, The contact member is provided on the surface of a flat plate-shaped reinforcing member at least a part of which is located on the side where the sample plate is inserted rather than the contact member, and a V-shaped groove is formed at the end on the side where the sample plate is inserted, thereby being formed in the tapered shape.

[0095] The thickness of the contact member is, for example, about 0.1 mm, and it is not easy to form the end of a member with such a thickness in a tapered shape. In the sample plate holder according to Item 13, the contact member is provided on the surface of a flat plate-shaped reinforcing member, and by forming a V-shaped groove at the end on the side where the sample plate is inserted, which is the boundary thereof, the end of the contact member can be formed in a tapered shape.

[0096] (Item 14) The sample plate holder according to Item 14 is the sample plate holder according to Item 12 or Item 13, and further, A side member located outside the short side of the sample plate is provided, The contact member extends from the side member toward the inside of the sample plate, and is a member having a depression formed at the base on the side where the sample plate is inserted.

[0097] In the sample plate holder according to Item 14, the contact member extends from a side member provided outside the short side of the sample plate toward the inside of the sample plate. For example, when forming a contact member having a rectangular shape in plan view, it is difficult to form the end on the side where the sample plate is inserted completely straight, and it often has a shape where the hem spreads toward the base side. Then, when inserting the sample plate, the sample plate gets caught on the step of the hem portion. In the sample plate holder according to Item 14, since a depression is provided at the base of the contact member on the side where the sample plate is inserted, there is no catching when inserting the sample plate.

[0098] (Item 15) The mass spectrometer according to Item 15 a sample plate holder according to any one of Items 1 to 14, a laser light irradiation unit that irradiates a laser beam onto a sample placed on the sample plate held by the sample plate holder, and a mass spectrometry unit that mass-analyzes ions generated from the sample by the irradiation of the laser beam are provided.

[0099] The sample plate holder described in Items 1 to 14 can be suitably used in the mass spectrometer according to Item 15, which particularly has a configuration for generating ions from a sample by irradiation with a laser beam.

[0100] (Item 16) The mass spectrometer according to Item 16 is the mass spectrometer according to Item 15, and further a stage on which the sample plate holder is set, a stage moving mechanism that moves the stage so that the laser beam is irradiated onto each of a plurality of measurement points distributed on the sample held by the sample plate, and an image data creation unit that creates image data showing the distribution of the target substance on the surface of the sample based on the mass spectrometry data obtained at the plurality of measurement points are provided.

[0101] The sample plate holder according to any one of claims 1 to 14 can be preferably used in the mass spectrometer according to claim 16, which performs so-called imaging mass spectrometry that particularly performs mass spectrometry at each of a plurality of measurement points on a sample and creates image data showing the distribution of a target substance on the surface of the sample based on the mass spectrometry data obtained at each measurement point.

[0102] (Claim 17) The mass spectrometer according to claim 17 is the mass spectrometer according to claim 15 or 16, wherein the laser light irradiation unit generates ions from the sample through a matrix substance applied or mixed with the sample.

[0103] The sample plate holder according to any one of claims 1 to 14 can be preferably used in the mass spectrometer according to claim 15, which has an ion source for ionizing a sample by a Matrix-Assisted Laser Desorption / Ionization method.

Explanation of Signs

[0104] 1... Mass spectrometer (MALDI-TOF MS) 10... Chamber 12... Stage 13... Laser light irradiation unit 14... Concave mirror 17... Imaging unit 18... Stage drive unit 19... Gate valve 21... Acceleration electrode 22... Ion lens 30... Mass analysis unit 31... Flight tube 32... Reflectron 33... Back plate 34... Ion detector 40... Control and processing unit 41... Storage unit 42... Measurement control unit 43…Analysis processing unit 44…Input unit 45…Display unit 5…Sample plate 6, 7, 8, 9…Sample plate holder 61, 71…Upper frame member 611…Overhanging piece (reinforcing member) 612 - 614, 912 - 914…Overhanging part (contact member) 62…Lower frame member 621…Grip part 631 - 633, 832…Pressing spring (biasing member) 64, 65…Screw 8321…Linear part 8322…Extension part 834…Fixing part 8341…Opening 8351, 8352…Washer 86, 96…Wall part (side member) 87, 97…Leaf spring 9121, 9131, 9141…Depression 9211…Screw mounting surface 981 - 983…V - groove C…Ion optical axis S…Sample

Claims

[

1. ] An urging member that presses one surface of the sample plate, and a contact member that contacts the other surface of the sample plate only at three locations that are not in a straight line in a plan view A sample plate holder for a mass spectrometer comprising: [

2. ] The sample plate holder for a mass spectrometer according to claim 1, wherein the contact member is integrally formed with a reinforcing member having a larger area than the contact member in a plan view. [

3. ] The sample plate is substantially rectangular, The sample plate holder for a mass spectrometer according to claim 2, wherein the contact member is integrally formed with reinforcing members provided along the respective short sides of the sample plate on one surface of the sample plate. [

4. ] The sample plate holder for a mass spectrometer according to claim 1, wherein at least one of the three locations is located in each of two regions divided by a plane passing through the center of gravity of the sample plate and perpendicular to the surface of the sample plate. [

5. ] The sample plate holder according to claim 1, wherein the urging member contacts an edge of the sample plate. [

6. ] The urging member is three leaf springs, and the three leaf springs are each inclined with respect to the surface so as to move away from the surface of the sample plate from the outside to the inside of the sample plate. The sample plate holder according to claim 1. [

7. ] A first leaf spring, which is one of the three leaf springs, is arranged along one side of the sample plate, The sample plate holder according to claim 6, wherein second and third leaf springs, which are two of the three leaf springs, are arranged along a side opposite to the one side. [

8. ] The third leaf spring is arranged inside the sample plate with respect to the second leaf spring, and has a linear portion and an extension portion extending from the linear portion to the outside of the sample plate. The sample plate holder according to claim 7. [

9. ] Further, a first frame member where the contact member is provided, a member fixed to the first frame member, and a second frame member to which the three leaf springs are attached comprising The sample plate holder according to claim 6, wherein the sample plate is held between the first frame member and the second frame member. [

10. ] The sample plate holder according to claim 9, wherein the second frame member is provided with an attachment surface inclined with respect to the surface of the sample plate, and the three leaf springs are attached to the attachment surface.

11. The sample plate holder according to claim 9, wherein the second frame member is provided with an attachment surface parallel to the surface of the sample plate, and the leaf spring is attached to the attachment surface via an inclined member having an inclined surface inclined with respect to the surface.

12. The sample plate holder according to claim 9, wherein a portion of the contact member located on the side where the sample plate is inserted is formed in a tapered shape.

13. The sample plate holder according to claim 12, wherein at least a part of the contact member is provided on the surface of a flat plate-shaped reinforcing member located on the side where the sample plate is inserted rather than the contact member, and a V-shaped groove is formed at an end on the side where the sample plate is inserted, thereby forming the tapered shape.

14. Furthermore, a side member located outside the short side of the sample plate is provided, The sample plate holder according to claim 12, wherein the contact member extends from the side member toward the inside of the sample plate, and a depression is formed at the base on the side where the sample plate is inserted.

15. The sample plate holder according to any one of claims 1 to 14, a laser light irradiation unit that irradiates a laser beam onto a sample placed on the sample plate held by the sample plate holder, a mass spectrometry unit that mass-analyzes ions generated from the sample by the irradiation of the laser beam A mass spectrometer comprising:

16. Furthermore, a stage on which the sample plate holder is set, a stage moving mechanism that moves the stage so that the laser beam is irradiated onto each of a plurality of measurement points distributed on the sample held by the sample plate, an image data creation unit that creates image data showing the distribution of the target substance on the surface of the sample based on the mass spectrometry data obtained at the plurality of measurement points The mass spectrometer according to claim 15, comprising:

17. The mass spectrometer according to claim 15, wherein the laser light irradiation unit generates ions from the sample through a matrix substance applied or mixed with the sample.

Images