Sample support, ionization method, and mass spectrometry method

Abstract

To effectively suppress generation of noise components when a sample is ionized.SOLUTION: A sample supporting body 1 includes a substrate 2 having a first surface 2a, a second surface 2b located on the opposite side to the side where the first surface 2a is located, and an irregular porous structure 3 with an opening in the first surface 2a. A porous structure 3 is formed of an aggregate of a plurality of beads 4. The porous structure 3 has a joint part 5 in which there are recesses between the beads 4 next to each other joining to each other. A conductive layer 6 is formed in a part which forms at least a first surface 2a of the surfaces 4a of the beads 4 and the joint part 5. A protective layer 7 is formed to cover the surfaces 4a of the beads 4, the joint part 5, and the conductive layer 6.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to sample supports, ionization methods, and mass spectrometry methods. [Background technology]

[0002] A sample support for ionizing a sample such as a biological sample is known (for example, Patent Document 1). This sample support has a porous structure formed so that a first surface and a second surface are in communication with each other. A conductive layer is provided on the first surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 155741 Summary of the Invention [Problem to be solved by the invention]

[0004] In the sample support described above, the components of the sample are ionized by irradiating an energy beam such as a laser beam onto the sample transferred onto the first surface (or the sample sucked up from the second surface side to the first surface side). Here, if components derived from the substrate (porous structure) and the conductive layer are generated as noise components (background noise) when the substrate is irradiated with laser beam, the detection accuracy of the ionized sample components may be reduced.

[0005] An object of the present disclosure is to provide a sample support, an ionization method, and a mass spectrometry method that can effectively suppress the generation of noise components when ionizing a sample. [Means for solving the problem]

[0006] A sample support according to one aspect of the present disclosure is a sample support for ionizing a sample, comprising a substrate having a first surface, a second surface opposite the first surface, and an irregular porous structure opening to the first surface, wherein the porous structure is formed by an aggregate of a plurality of particles, and the porous structure has junctions where adjacent particles are joined to form recesses between the particles, and a conductive layer is provided on at least the portion of the surfaces and junctions of the plurality of particles that constitutes the first surface, and a protective layer is provided to cover the surfaces of the plurality of particles, the junctions, and the conductive layer.

[0007] In the sample support, a conductive layer is provided on the portion of the porous structure formed by an aggregate of a plurality of particles that constitutes the first surface. A protective layer is also provided to cover the surfaces, joints, and conductive layer of the plurality of particles. That is, the protective layer protects the substrate material (i.e., the particles) and the conductive layer from exposure to the outside. This effectively prevents components derived from the substrate material or the conductive layer from being generated as noise components when irradiating the first surface of the substrate with an energy beam to ionize the sample.

[0008] The protective layer may be made of at least one of an oxide, a fluoride, a nitride, a carbide, and a metal. According to the above-mentioned configuration, the protective layer having the above-mentioned protective function can be suitably formed.

[0009] The protective layer may be made of at least one of aluminum oxide, magnesium oxide, hafnium oxide, silicon oxide, magnesium fluoride, aluminum nitride, silicon nitride, silicon carbide, tungsten, hafnium, diamond, and graphite. According to the above configuration, the protective layer having the above-mentioned protective function can be suitably formed.

[0010] The average diameter of the joints in the porous structure may be 1 / 10 or more and less than the average diameter of the particles in the porous structure. According to the above configuration, the strength of the joints in the porous structure can be ensured, and the substrate strength (rigidity) sufficient to withstand the transfer of a sample to the first surface can be ensured.

[0011] The particles may be glass beads. According to the above-mentioned configuration, a substrate having an irregular porous structure can be obtained suitably and inexpensively.

[0012] The protective layer may be an ALD layer. According to the above configuration, the protective layer can be formed densely and continuously on the surfaces, junctions, and conductive layer of the plurality of particles by atomic layer deposition (ALD). This effectively prevents the particle surfaces, junctions, and conductive layer from being exposed to the outside, and more effectively prevents components derived from the substrate material or the conductive layer from being generated as noise components.

[0013] The thickness of the protective layer may be 10 nm or less. According to the above configuration, by making the protective layer covering the conductive layer sufficiently thin, it is possible to appropriately apply a voltage to the conductive layer through the protective layer. Furthermore, by making the protective layer sufficiently thin, it is possible to suppress charge-up of the protective layer.

[0014] An ionization method according to another aspect of the present disclosure includes a first step of preparing the sample support, a second step of transferring a sample to the first surface, and a third step of ionizing components of the sample by irradiating the first surface with an energy beam.

[0015] According to the above ionization method, when a transfer method is adopted in which a sample to be ionized is transferred to the first surface of the above sample support, the same effect as that of the above sample support can be obtained. That is, when an energy beam is irradiated onto the first surface of the substrate to ionize the sample, components originating from the material of the substrate or the conductive layer can be effectively suppressed from being generated as noise components.

[0016] An ionization method according to another aspect of the present disclosure includes a first step of preparing a sample support having a porous structure configured to connect a first surface and a second surface; a second step of placing the sample support on a sample so that the second surface faces the sample; and a third step of ionizing the sample components by irradiating an energy beam onto the first surface after the components of the sample have migrated from the second surface side to the first surface side by capillary action.

[0017] According to the above ionization method, when a suction method is adopted in which the sample to be ionized is sucked up from the second surface side to the first surface side of the above-mentioned sample support by utilizing capillary action, the same effect as that of the above-mentioned sample support can be obtained. That is, when an energy beam is irradiated onto the first surface of the substrate to ionize the sample, components originating from the material of the substrate or the conductive layer can be effectively suppressed from being generated as noise components.

[0018] A mass spectrometry method according to another aspect of the present disclosure includes the first, second, and third steps of the ionization method described above, and a fourth step of detecting the components ionized in the third step.

[0019] According to the mass spectrometry method, by including the first, second, and third steps of the ionization method, the same effects as those of the ionization method can be obtained. [Effects of the Invention]

[0020] According to the present disclosure, it is possible to provide a sample support, an ionization method, and a mass spectrometry method that can effectively suppress the generation of noise components when ionizing a sample. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view showing an embodiment of a sample support. [Figure 2] 2 is an enlarged image of region A shown in FIG. 1. [Figure 3]FIG. 3 is a diagram schematically illustrating the state of a bead assembly that constitutes a first surface. [Figure 4] FIG. 2 is a diagram showing a second step in the mass spectrometry method of one embodiment. [Figure 5] 1 is a configuration diagram of a mass spectrometer in which a mass spectrometry method according to an embodiment is performed; [Figure 6] FIG. 1 is a diagram showing the measurement results of blank noise in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Note that in the drawings, some parts are exaggerated to clearly explain the characteristics of the embodiments. Therefore, the dimensional ratios in the drawings may differ from the actual dimensional ratios.

[0023] [Sample support] As shown in FIG. 1, the sample support 1 includes a substrate 2. As an example, the substrate 2 is formed in the shape of a rectangular plate. The substrate 2 has a first surface 2a and a second surface 2b opposite to the first surface 2a. When viewed in the thickness direction of the substrate 2 (i.e., the direction in which the first surface 2a and the second surface 2b face each other), the length of one side of the substrate 2 is, for example, about several centimeters. The thickness of the substrate 2 (the distance from the first surface 2a to the second surface 2b) is, for example, about 100 μm to 1500 μm.

[0024] As shown in FIG. 2, the substrate 2 has an irregular porous structure 3 that opens to the first surface 2a. Note that FIG. 2 shows the state before the formation of the conductive layer 6 and protective layer 7, which will be described later. An irregular porous structure is, for example, a structure in which voids (pores) extend in irregular directions and are irregularly distributed in three dimensions. For example, the irregular porous structure includes a structure in which a single inlet (opening) on ​​the first surface 2a enters the substrate 2 and branches into multiple paths, or a structure in which multiple inlets (openings) on the first surface 2a enter the substrate 2 and merge into a single path. On the other hand, a structure in which multiple pores that extend linearly along the thickness direction of the substrate 2 from the first surface 2a to the second surface 2b are provided as the main pores (i.e., a regular structure composed mainly of pores extending in one direction) is not included in the irregular porous structure.

[0025] The porous structure 3 is formed, for example, by an aggregate of a plurality of bead-like particles. An aggregate of a plurality of bead-like particles is a structure in which a plurality of particles are gathered so as to be in contact with one another. An example of an aggregate of a plurality of particles is a structure in which a plurality of particles are adhered or bonded to one another. In this embodiment, the porous structure 3 is a bead aggregate (aggregate) formed by bonding a plurality of spherical beads 4 (particles) to one another. That is, the substrate 2 is composed of a bead aggregate (porous structure 3) obtained by bonding a plurality of beads 4 to one another and forming the beads 4 into a rectangular plate shape. The porous structure 3 has a portion occupied by the plurality of beads 4 and gaps S between the plurality of beads 4.

[0026] In this embodiment, the beads 4 are glass beads. In this case, the bead aggregate is, for example, a sintered body of a plurality of glass beads (beads 4). According to the above configuration, by using glass beads, a substrate 2 having an irregular porous structure 3 can be obtained suitably and inexpensively. In this embodiment, the entire substrate 2 is composed of the porous structure 3. That is, the porous structure 3 is formed over the entire area from the first surface 2a to the second surface 2b of the substrate 2. As a result, the porous structure 3 is formed so as to connect the first surface 2a and the second surface 2b.

[0027] As shown in FIG. 3, adjacent beads 4 are bonded (fused) to each other. The bonding of adjacent beads 4 forms recesses between the beads 4. That is, the porous structure 3 has bonding portions 5 that form the recesses. Here, the substrate 2 has a degree of rigidity that allows the second step (transfer of the sample Sa (see FIG. 4)) of the ionization method, which will be described later, to be performed. If the rigidity of the substrate 2 is insufficient, the substrate 2 may be damaged when the sample Sa is pressed against the first surface 2a or when the sample Sa is peeled off from the first surface 2a. Therefore, the substrate 2 has a rigidity that can withstand the transfer of the sample Sa (i.e., the operation of pressing the sample Sa against the first surface 2a and the operation of peeling off the sample Sa from the first surface 2a) (i.e., a degree of rigidity that prevents the substrate 2 from being damaged by the transfer of the sample Sa). In this embodiment, the average diameter of the joints 5 formed between adjacent beads 4 (average of the diameters d1 of the joints 5) is at least 1 / 10 of the average diameter of the beads 4 (average of the diameters d2 of the beads 4) but less than the average diameter of the beads 4. This configuration ensures the strength of the joints 5 in the porous structure 3, and also ensures the substrate strength (rigidity) sufficient to withstand the transfer of the sample Sa to the first surface 2a.

[0028] As shown in FIG. 3 , a conductive layer 6 is provided on at least the portion of the surfaces 4a and joints 5 of the beads 4 that constitutes the first surface 2a. Here, the portion that constitutes the first surface 2a is the portion that is exposed on the first surface 2a side of the substrate 2. For example, this portion is the portion that is visible when the substrate 2 is viewed from a position facing the first surface 2a. In the example of FIG. 3 , the two beads 4 that are joined to each other are arranged side by side in a direction perpendicular to the thickness direction of the substrate 2, and the top surfaces of the two beads 4 constitute the first surface 2a. In other words, the conductive layer 6 straddles the top surfaces of the two beads 4, covering the surfaces 4a of the beads 4 and joints 5 that are exposed on the first surface 2a side.

[0029] The conductive layer 6 is made of a conductive material. For the reasons described below, it is preferable to use a metal that has low affinity (reactivity) with the sample and high conductivity as the material for the conductive layer 6.

[0030] For example, if the conductive layer 6 is made of a metal such as Cu (copper) that has a high affinity for a sample such as a protein, the sample may be ionized with Cu atoms attached to the sample molecules during the sample ionization process described below, and the detection results in the mass spectrometry method described below may be distorted by the amount of the attached Cu atoms. Therefore, it is preferable to use a metal that has a low affinity for the sample as the material for the conductive layer 6.

[0031] On the other hand, the higher the conductivity of a metal, the easier and more stable the application of a constant voltage. Therefore, when the conductive layer 6 is made of a metal with high conductivity, it becomes possible to uniformly apply a voltage to the first surface 2a of the substrate 2. Furthermore, the higher the conductivity of a metal, the higher the thermal conductivity tends to be. Therefore, when the conductive layer 6 is made of a metal with high conductivity, it becomes possible to efficiently transmit the energy of an energy beam (e.g., laser light) irradiated onto the substrate 2 to the sample via the conductive layer 6. Therefore, it is preferable to use a metal with high conductivity as the material for the conductive layer 6.

[0032] From the above viewpoints, it is preferable to use, for example, Au (gold), Pt (platinum), etc. as the material for the conductive layer 6. The conductive layer 6 is formed to a thickness of about 1 nm to 350 nm by, for example, plating, atomic layer deposition (ALD), vapor deposition, sputtering, etc. Note that, for example, Cr (chromium), Ni (nickel), Ti (titanium), etc. may also be used as the material for the conductive layer 6.

[0033] The conductive layer 6 is formed by, for example, performing the vapor deposition method, sputtering method, or the like described above from the first surface 2a side so as to cover the surfaces 4a and bonding portions 5 of the beads 4 that are exposed on the first surface 2a side, as shown in Fig. 3. On the other hand, when the conductive layer 6 is formed by ALD, the conductive layer 6 can be formed so as to cover the entire surfaces 4a and bonding portions 5 of each bead 4. In this way, the conductive layer 6 may be provided not only on the portions of the surfaces 4a and bonding portions 5 of each bead 4 that constitute the first surface 2a, but also on the entire surfaces 4a and bonding portions 5 of each bead 4.

[0034] As shown in FIG. 3 , the protective layer 7 is provided so as to cover the surfaces 4 a of the beads 4, the bonding portions 5, and the conductive layer 6. The protective layer 7 is, for example, formed densely and continuously on the surfaces 4 a of the beads 4, the bonding portions 5, and the conductive layer 6 without any gaps. The protective layer 7 prevents the beads 4 and the conductive layer 6 from being directly irradiated with laser light L (a type of energy beam) when the first surface 2 a of the substrate 2 is irradiated with the laser light L in the third step described below. This prevents components derived from the material of the substrate 2 (i.e., the beads 4) and the conductive layer 6 from being generated as noise components. In other words, the protective layer 7 has a noise reduction function that suppresses the generation of the above-mentioned noise components.

[0035] To effectively achieve the noise reduction function, the protective layer 7 is preferably formed of a material having a relatively high melting point or evaporation onset temperature. For example, the protective layer 7 may be formed of an oxide, a fluoride, a nitride, a carbide, a metal, or the like. The protective layer 7 may also be formed of an oxide such as aluminum oxide, magnesium oxide, hafnium oxide, or silicon oxide, a fluoride such as magnesium fluoride, a nitride such as aluminum nitride or silicon nitride, or a carbide such as silicon carbide. Alternatively, the protective layer 7 may be formed of a metal such as tungsten or hafnium, or diamond or graphite. By forming the protective layer 7 from the above-mentioned materials, the protective layer 7 having the above-mentioned protection function (noise reduction function) can be suitably formed.

[0036] The protective layer 7 may be configured as an ALD layer. That is, the protective layer 7 may be formed by atomic layer deposition (ALD). In this case, as shown in FIG. 3 , the protective layer 7 can be formed densely and continuously on the surfaces 4 a, the joints 5, and the conductive layer 6 of the plurality of beads 4 by ALD. This makes it possible to suitably prevent the surfaces 4 a, the joints 5, and the conductive layer 6 of the beads 4 from being exposed to the outside, and more effectively prevents components derived from the material of the substrate 2 (i.e., the beads 4) or the conductive layer 6 from being generated as noise components.

[0037] However, the method for forming the protective layer 7 is not limited to ALD. For example, the protective layer 7 may be formed by a general film formation method, such as gas phase film formation, such as physical vapor deposition (PVD) such as ion plating or chemical vapor deposition (CVD), or liquid phase film formation, such as a sol-gel method or coating. Furthermore, the protective layer 7 does not necessarily have to be formed so as to cover the surfaces 4a of all the beads 4 constituting the substrate 2. For example, the protective layer 7 may be formed so as to cover the surfaces 4a of some of the beads 4 located on the first surface 2a side of the substrate 2 (including the beads 4 constituting the first surface 2a).

[0038] The thickness of the protective layer 7 is, for example, 100 nm or less. For example, the thickness of the protective layer 7 may be 10 nm or less from the viewpoint of imparting conductivity to the conductive layer 6 and preventing charge-up. By making the protective layer 7 covering the conductive layer 6 sufficiently thin, a voltage can be appropriately applied to the conductive layer 6 via the protective layer 7 in the third step described below. Furthermore, by making the protective layer 7 sufficiently thin, charge-up of the protective layer 7 can also be suppressed.

[0039] [Ionization method and mass spectrometry method] An example of an ionization method and a mass spectrometry method using a sample support 1 will be described. First, the above-mentioned sample support 1 is prepared as a sample support for ionizing a sample (first step). The sample support 1 may be prepared by being manufactured by the practitioner of the ionization method and the mass spectrometry method, or may be provided by a manufacturer or seller of the sample support 1.

[0040] Next, as shown in Fig. 4, the sample Sa is transferred to the first surface 2a of the substrate 2 (second step). In the example of Fig. 4, the sample Sa is a slice of fruit (lemon). For example, by pressing the sample Sa against the first surface 2a of the substrate 2, the component Sa1 (see Fig. 5) of the sample Sa is adhered to the first surface 2a.

[0041] Next, after the component Sa1 of the sample Sa has adhered to the first surface 2a, the component Sa1 of the sample Sa is ionized by irradiating the first surface 2a with an energy beam while applying a voltage to the first surface 2a (conductive layer 6) (third step). As an example, the third step can be performed using a mass spectrometer 10 shown in FIG. 5. The mass spectrometer 10 includes a support unit 12, an irradiation unit 13, a voltage application unit 14, an ion detection unit 15, a camera 16, a control unit 17, and a sample stage 18.

[0042] The sample support 1 is placed on a support section 12. The support section 12 is placed on a sample stage 18. Here, as an example, the sample support 1 is fixed to the support substrate 8 via conductive tape 9, with the second surface 2b of the substrate 2 placed on the support surface 8a of the support substrate 8. With the sample support 1 fixed to the support substrate 8 in this manner, the support substrate 8 is placed on the support section 12. The conductive tape 9 is provided on the edge of the substrate 2 and is formed across the first surface 2a of the substrate 2 and the support surface 8a of the support substrate 8. The first surface 2a and the support surface 8a are electrically connected via the conductive tape 9. The support substrate 8 can be formed, for example, by a slide glass. In this embodiment, as an example, the support substrate 8 is a glass substrate (ITO slide glass) on which a transparent conductive film such as an ITO (indium tin oxide) film is formed, and the surface of the transparent conductive film serves as the support surface 8a. That is, in this embodiment, the entire support surface 8a is conductive.

[0043] The irradiation unit 13 irradiates the first surface 2a of the sample support 1 with an energy beam such as laser light L. The voltage application unit 14 applies a voltage to the first surface 2a of the sample support 1. The ion detection unit 15 detects ionized sample components (sample ions Sa2). The camera 16 acquires a camera image including the position irradiated with the laser light L by the irradiation unit 13. The camera 16 is, for example, a small CCD camera attached to the irradiation unit 13. The control unit 17 controls the operations of the sample stage 18, the camera 16, the irradiation unit 13, the voltage application unit 14, and the ion detection unit 15. The control unit 17 is, for example, a computer device equipped with a processor (for example, a CPU, etc.) and memory (for example, a ROM, RAM, etc.).

[0044] A voltage is applied to the support surface 8a of the support substrate 8 by the voltage application unit 14. As a result, a voltage is applied to the conductive layer 6 (see FIG. 3) on the first surface 2a of the substrate 2 via the support surface 8a and the conductive tape 9. Note that a protective layer 7 is formed on the conductive layer 6, and as described above, the protective layer 7 is formed thin enough to allow a voltage to be applied to the conductive layer 6, so that a voltage is applied to the conductive layer 6 via the protective layer 7.

[0045] Next, the control unit 17 operates the irradiation unit 13 based on the image acquired by the camera 16. Specifically, the control unit 17 operates the irradiation unit 13 so that the laser light L is irradiated onto the first surface 2a within the laser irradiation range (for example, a region where the component Sa1 of the sample identified based on the image acquired by the camera 16 exists).

[0046] As an example, the control unit 17 moves the sample stage 18 and controls the operation (such as the irradiation timing) of the irradiation unit 13 to irradiate the laser light L. That is, after confirming that the sample stage 18 has moved a predetermined distance, the control unit 17 causes the irradiation unit 13 to irradiate the laser light L. For example, the control unit 17 repeats the movement (scanning) of the sample stage 18 and the irradiation of the laser light L by the irradiation unit 13 so as to raster scan the laser irradiation range. Note that the irradiation position on the first surface 2a may be changed by moving the irradiation unit 13 instead of the sample stage 18, or by moving both the sample stage 18 and the irradiation unit 13.

[0047] In the third step described above, the component Sa1 of the sample on the first surface 2a is ionized, and sample ions Sa2 are emitted. Specifically, energy is transferred from the conductive layer 6, which has absorbed the energy of the laser light L, to the component Sa1 of the sample on the first surface 2a, and the component Sa1 that has acquired the energy is vaporized and acquires an electric charge, becoming sample ions Sa2. The emitted sample ions Sa2 move while accelerating toward a ground electrode (not shown) provided between the sample support 1 and the ion detector 15. That is, the sample ions Sa2 move while accelerating toward the ground electrode due to the potential difference generated between the conductive layer 6 to which a voltage is applied and the ground electrode. Then, the sample ions Sa2 are detected by the ion detector 15 (fourth step).

[0048] The above first to third steps correspond to the ionization method using the sample support 1. The above first to fourth steps correspond to the mass spectrometry method using the sample support 1.

[0049] [Action and effect] In the above-described sample support 1, a conductive layer 6 (see FIG. 3 ) is provided on a portion of the porous structure 3 formed by an aggregate of a plurality of bead-shaped particles (beads 4 in this embodiment) that constitutes the first surface 2a. In addition, a protective layer 7 is provided so as to cover the surfaces 4a of the plurality of beads 4, the bonding portions 5, and the conductive layer 6. That is, the protective layer 7 protects the material of the substrate 2 (i.e., the beads 4) and the conductive layer 6 from being exposed to the outside. This effectively prevents components derived from the material of the substrate 2 or the conductive layer 6 from being generated as noise components when the first surface 2a of the substrate 2 is irradiated with an energy beam to ionize the sample (i.e., the above-described third step).

[0050] Furthermore, according to the ionization method (first to third steps) using the sample support 1, when a transfer method is adopted in which the sample Sa to be ionized is transferred to the first surface 2a of the sample support 1, the same effects as those of the above-mentioned sample support 1 can be obtained. That is, when the first surface 2a of the substrate 2 is irradiated with an energy beam to ionize the sample, components originating from the material of the substrate 2 or the conductive layer 6 can be effectively suppressed from being generated as noise components. Furthermore, according to the mass spectrometry method (first to fourth steps) using the sample support 1, by including the first, second, and third steps of the above-mentioned ionization method, the same effects as those of the above-mentioned ionization method can be obtained.

[0051] FIG. 6 shows the results of measuring blank noise for the example and comparative example. In FIG. 6, the horizontal axis represents mass-to-charge ratio (m / z), and the vertical axis represents signal intensity (arbitrary units: arb. units). Specifically, FIG. 6 shows mass spectra obtained by the above-described mass spectrometry method for each of the example and comparative example in a state in which there is no sample to be analyzed (i.e., a state in which no sample component Sa1 is attached to the first surface 2a). In FIG. 6, to facilitate comparison between the mass spectrum of the example and the mass spectrum of the comparative example, the origin of the signal intensity of the mass spectrum of the comparative example (i.e., the value corresponding to a signal intensity of 0) has been shifted by "+500."

[0052] The example is a sample support having a configuration similar to that of the above-described sample support 1. More specifically, the example is a sample support having a protective layer 7 (see FIG. 3) formed so as to cover the surfaces 4a of the beads 4, the bonding portions 5, and the conductive layer 6. In the example, the protective layer 7 is an ALD film formed by depositing aluminum oxide by ALD. The thickness of the protective layer 7 is 8 nm.

[0053] The comparative example is a sample support having a configuration in which the protective layer 7 is omitted from the above-described sample support 1. That is, in the comparative example, the surfaces 4a of the beads 4, the bonding portions 5, and the conductive layer 6 are exposed on the first surface 2a side of the substrate 2.

[0054] 6, in the comparative example, significant blank noise (i.e., background noise detected in the absence of a sample) was detected, particularly in the low mass region (60 m / z to 400 m / z). If the sample to be analyzed has a peak signal in the low mass region, the presence of the blank noise can make it difficult to detect (analyze) the peak signal.

[0055] On the other hand, in the Examples in which the above-described protective layer 7 was formed, although some blank noise was detected in the low mass region, it was confirmed that the generation of blank noise was significantly suppressed compared to the Comparative Example. That is, it was confirmed that, on the first surface 2a irradiated with the energy ray (laser light L), the surface 4a of the beads 4, the bonding portions 5, and the conductive layer 6 were covered with the protective layer 7, thereby reducing the blank noise originating from the beads 4 and the conductive layer 6. More specifically, it was confirmed that the types of blank noise (the number of peak signals) in the Examples were reduced compared to the types of blank noise in the Comparative Example, and that the signal intensity of the blank noise in the Examples was smaller than the signal intensity of the blank noise in the Comparative Example.

[0056] [Variations] The present disclosure is not limited to the above-described embodiments. The materials and shapes of each component are not limited to those described above, and various materials and shapes can be used. Furthermore, some components of one embodiment or modified example described above can be applied to other embodiments or modified examples.

[0057] For example, in the above embodiment, the sample support 1 is configured to include only the substrate 2, but the sample support 1 may also include members other than the substrate 2. For example, a support member (such as a frame) for supporting the substrate 2 may be provided on a part of the substrate 2 (such as a corner).

[0058] Furthermore, the sample Sa is not limited to the slice of fruit (lemon) exemplified in the above embodiment. The sample Sa may have a flat surface or an uneven surface. The sample Sa may also be something other than fruit, such as a plant leaf. In this case, by transferring the components of the surface of the leaf, which is the sample Sa, to the first surface 2a, it becomes possible to perform imaging mass spectrometry of the surface (veins) of the leaf.

[0059] Furthermore, when the entire substrate 2 is formed of the porous structure 3 as in the above embodiment, i.e., when the sample support 1 has a porous structure 3 configured to connect the first surface 2a and the second surface 2b, the above-mentioned second step may be modified as follows. That is, in the second step, the sample support 1 may be placed on the sample Sa so that the second surface 2b of the substrate 2 faces the sample Sa. For example, in the above embodiment, the sample Sa may be placed between the support surface 8a of the support substrate 8 and the second surface 2b of the sample support 1. In this case, the component Sa1 of the sample Sa moves from the second surface 2b side of the substrate 2 to the first surface 2a side of the substrate 2 through the porous structure 3 (i.e., the gap S) by capillary action. That is, in this modification, in the third step, the component Sa1 of the sample moves from the second surface 2b side to the first surface 2a side by capillary action, and then the first surface 2a is irradiated with the laser light L. According to the ionization method and mass spectrometry method including the second and third steps of the above-described modified example, when a suction method is adopted in which the sample Sa to be ionized is sucked up from the second surface 2b side to the first surface 2a side of the sample support 1 by utilizing capillary action, the same effect as that of the above-described sample support 1 can be obtained. That is, when an energy beam is irradiated onto the first surface 2a of the substrate 2 to ionize the sample, it is possible to effectively suppress the generation of components derived from the material of the substrate 2 or the conductive layer 6 as noise components.

[0060] Furthermore, in the above embodiment, the entire substrate 2 is constituted by the porous structure 3, which is a bead assembly. However, the porous structure 3 may be formed only in a portion of the substrate 2. For example, the porous structure 3 may be formed only in a central region (a portion of the first surface 2a) of the substrate 2, which is defined as a measurement region for transferring the sample Sa, and the porous structure 3 may not be formed in other portions of the substrate 2. Furthermore, the porous structure 3 does not have to be formed over the entire area from the first surface 2a to the second surface 2b. That is, the porous structure 3 only needs to be open to at least the first surface 2a, and may not be open to the second surface 2b. For example, the substrate 2 may be constituted by a flat plate and a porous structure provided on the plate. As an example, the substrate 2 may be constituted by a glass plate and a glass bead assembly (porous structure) provided on the glass plate. In this case, the surface of the glass bead assembly opposite the glass plate is the first surface 2a, and the surface of the glass plate opposite the glass bead assembly is the second surface 2b.

[0061] Furthermore, the particles that make up the porous structure 3 are not limited to roughly spherical beads, and may have a shape other than roughly spherical.

[0062] Furthermore, in the mass spectrometry method using the sample support 1, the target to which the voltage is applied by the voltage application unit 14 is not limited to the support surface 8a of the support substrate 8. For example, the voltage may be applied to a member other than the support substrate 8 (for example, the conductive tape 9).

[0063] In the mass analysis method using the sample support 1, the mass spectrometer 10 may be a scanning mass spectrometer or a projection mass spectrometer. In the scanning type, a signal of one pixel corresponding to the spot diameter of the laser light L is acquired with each irradiation of the laser light L by the irradiation unit 13. That is, scanning (changing the irradiation position) and irradiation of the laser light L are performed for each pixel. On the other hand, in the projection type, a signal of an image (multiple pixels) corresponding to the spot diameter of the laser light L is acquired with each irradiation of the laser light L by the irradiation unit 13. In the projection type, if the spot diameter of the laser light L includes the entire sample to be analyzed, imaging mass spectrometry can be performed with a single irradiation of the laser light L. Note that in the projection type, if the spot diameter of the laser light L does not include the entire sample to be analyzed, scanning and irradiation of the laser light L can be performed in the same way as in the scanning type to acquire signals for the entire sample to be analyzed. The above-mentioned ionization method can also be used for other measurements and experiments, such as ion mobility measurements.

[0064] The use of the sample support 1 is not limited to ionizing a sample by irradiation with laser light L. The sample support 1 can be used for ionizing a sample by irradiation with energy rays such as laser light, electrospray, ion beam, and electron beam. In the above-described ionization method and mass analysis method, a sample can be ionized by irradiation with such energy rays. [Explanation of symbols]

[0065] 1...sample support, 2...substrate, 2a...first surface, 2b...second surface, 3...porous structure, 4...beads (particles), 4a...surface, 5...junction, 6...conductive layer, 7...protective layer, L...laser light (energy rays), Sa...sample, Sa1...component, Sa2...sample ion.

Claims

1. 1. A sample support for ionization of a sample, comprising: a substrate having a first surface, a second surface opposite the first surface, and an irregular porous structure opening to the first surface; the porous structure is formed by an aggregate of a plurality of particles, the porous structure has joints where adjacent particles are joined to form recesses between the particles, a conductive layer is provided on at least a portion of the surfaces of the plurality of particles and the joint portion that constitutes the first surface and is irradiated with an energy beam to ionize components of the sample; a protective layer is provided to cover the surfaces of the plurality of particles, the joints, and the conductive layer; Sample support.

2. the protective layer is formed of at least one of an oxide, a fluoride, a nitride, a carbide, and a metal; 2. The sample support of claim 1.

3. the protective layer is formed of at least one of aluminum oxide, magnesium oxide, hafnium oxide, silicon oxide, magnesium fluoride, aluminum nitride, silicon nitride, silicon carbide, tungsten, hafnium, diamond, and graphite; 2. The sample support of claim 1.

4. an average diameter of the joints in the porous structure is 1 / 10 or more of an average diameter of the particles in the porous structure and is less than the average diameter of the particles; A sample support according to any one of claims 1 to 3.

5. The particles are glass beads. A sample support according to any one of claims 1 to 4.

6. The protective layer is an ALD layer. A sample support according to any one of claims 1 to 5.

7. The thickness of the protective layer is 10 nm or less. A sample support according to any one of claims 1 to 6.

8. A first step of preparing a sample support according to claim 1; a second step of transferring a sample to the first surface; and a third step of irradiating the first surface with an energy beam to ionize components of the sample.

9. 2. The sample support according to claim 1, comprising: a first step of providing the sample support having the porous structure configured to communicate the first surface and the second surface; a second step of placing the sample support on the sample so that the second surface faces the sample; and a third step of ionizing the components of the sample by irradiating the first surface with an energy beam after the components of the sample have migrated from the second surface side to the first surface side by capillary action.

10. The first step, the second step, and the third step of the ionization method according to claim 8 or 9; a fourth step of detecting the components ionized in the third step.

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