Sample support, ionization method, and mass analysis method

Abstract

A sample support is a sample support for ionization of a sample. The sample support includes a substrate having a first surface having electrical insulation, a second surface opposite the first surface, and an irregular porous structure opened at least at the first surface.

Description

Technical Field

[0001] This invention relates to a sample support, an ionization method, and a mass analysis method. Background Technology

[0002] As a method for ionizing samples such as biological samples for quality analysis, desorption electrospray ionization (DESI) is known (see, for example, Patent Document 1). Desorption electrospray ionization is a method that desorbs and ionizes the sample by irradiating it with charged droplets.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-165116 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] In desorption electrospray ionization, for example, to improve signal intensity (sensitivity) in mass analysis, it is required to properly ionize the components of the sample.

[0008] The purpose of this invention is to provide a sample support capable of appropriately ionizing the components of a sample, an ionization method, and a quality analysis method capable of improving signal intensity.

[0009] Solutions for solving technical problems

[0010] One aspect of the present invention is a sample support for sample ionization. The sample support includes a substrate having: a first surface having electrical insulation, a second surface opposite to the first surface, and an irregular porous structure with an opening at least on the first surface.

[0011] In the aforementioned sample support, the first surface of the substrate is electrically insulating. Therefore, by irradiating the sample transferred to the first surface with charged microdroplets (desorption electrospray ionization), the sample can be appropriately desorbed and ionized. Furthermore, an irregular porous structure with openings on the first surface is formed on the substrate. This allows the sample transferred to the first surface to diffuse appropriately into the porous structure, thus appropriately adjusting the amount of sample remaining on the first surface. Through the above, the sample support can be used to appropriately ionize the components of the sample.

[0012] Porous structures can also be formed from aggregates of multiple powders. This allows the sample transferred to the first surface to be properly retained on the surface of each powder constituting the aggregate.

[0013] An insulating coating can also be applied to the first surface. Alternatively, the porous structure can be formed by an aggregate of multiple powders made of metal. In this case, the insulating coating makes the first surface of the substrate electrically insulating, allowing the use of a substrate made of a conductive material. This increases the freedom of choice in selecting the substrate material.

[0014] The powder can also be made of glass, metal oxide, or a metal with an insulating coating. Alternatively, the powder can be glass beads. In this case, the aforementioned substrate with an irregular porous structure can be obtained appropriately and inexpensively.

[0015] The porous structure can also be formed in a manner that connects the first surface and the second surface. In this case, the remaining components of the sample transferred to the first surface can more appropriately escape from the first surface side to the second surface side.

[0016] Another aspect of the ionization method of the present invention includes: a first step of preparing a sample support having a substrate having: a first surface having electrical insulation, a second surface opposite to the first surface, and an irregular porous structure with an opening at least on the first surface; a second step of transferring a sample onto the first surface; and a third step of ionizing the components of the transferred sample by irradiating the first surface with charged microdroplets and attracting the ionized components.

[0017] In the aforementioned ionization method, since the first surface of the substrate of the sample support is an electrically insulating component, even if a micro-droplet irradiation section with a high voltage is brought close to the first surface, the generation of discharge between the micro-droplet irradiation section and the sample support can be suppressed. Furthermore, as described above, because the substrate 2 has an irregular porous structure, the amount of sample remaining on the first surface can be appropriately adjusted. Therefore, according to this ionization method, by bringing the micro-droplet irradiation section close to the first surface and irradiating the first surface with charged micro-droplets, the components of the sample transferred to the first surface can be appropriately ionized.

[0018] The porous structure can be formed from an aggregate of multiple powders, and in the second step, the composition of the sample can be retained on the surface of the powders. Thus, the sample transferred to the first surface can be appropriately retained on the surface of the aggregate. As a result, in the third step, the composition of the sample can be appropriately ionized.

[0019] In the aforementioned ionization method, in the third step, the irradiation area of ​​the charged microdroplets can be moved relative to the first surface. The sample composition remaining on the first surface side of the substrate retains the sample's positional information (two-dimensional distribution information of the molecules constituting the sample). Therefore, by moving the irradiation area of ​​the charged microdroplets relative to the first surface, the sample composition can be ionized while maintaining the sample's positional information. Consequently, in the later step of detecting the ionized components, the two-dimensional distribution of the molecules constituting the sample can be imaged. Furthermore, as described above, since the microdroplet irradiation area can be brought closer to the first surface, the expansion of the irradiation area of ​​the charged microdroplets can be suppressed. Therefore, in the later step of detecting the ionized components, the two-dimensional distribution of the molecules constituting the sample can be imaged at high resolution.

[0020] Another aspect of the quality analysis method of the present invention includes: the first step, the second step and the third step of the above-described ionization method, and the fourth step of detecting the components ionized in the third step.

[0021] In the above-mentioned quality analysis method, as described above, the components of the sample are appropriately ionized by irradiation with charged micro-droplets, thus enabling an increase in signal intensity when detecting ionized components.

[0022] Invention Effects

[0023] According to the present invention, a sample support capable of appropriately ionizing the components of a sample, an ionization method, and a quality analysis method capable of improving signal intensity can be provided. Attached Figure Description

[0024] Figure 1 This is a perspective view of a specimen support body according to one embodiment.

[0025] Figure 2 yes Figure 1 A magnified image of region A shown.

[0026] Figure 3 This is a diagram showing the diameter of the joint and the diameter of the beads in a bead assembly.

[0027] Figure 4 This is a diagram illustrating the second step in a quality analysis method according to one embodiment.

[0028] Figure 5 This is a structural diagram of a quality analysis apparatus that implements one embodiment of a quality analysis method. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, identical or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted.

[0030] [Sample Support]

[0031] like Figure 1 As shown, 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. The first surface 2a is electrically insulating. In this embodiment, the substrate 2 is an electrically insulating component. Therefore, not only the first surface 2a, but the entire substrate 2 is electrically insulating. 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.

[0032] like Figure 2 As shown, an irregular porous structure 3 with an opening on the first surface 2a is formed on the substrate 2. An irregular porous structure is, for example, a structure in which pores (micropores) extend in irregular directions and are irregularly distributed in three dimensions. For example, a structure in which multiple paths branch into the substrate 2 from a single inlet (opening) on ​​the first surface 2a side, or a structure in which multiple inlets (openings) on the first surface 2a side merge into a single path into the substrate 2, is also included in the aforementioned irregular porous structure. On the other hand, a structure in which multiple micropores extending along the thickness direction of the substrate 2 from the first surface 2a to the second surface 2b are provided as the main micropores (i.e., a regular structure mainly composed of micropores extending in one direction) is not included in the irregular porous structure.

[0033] The porous structure 3 is formed, for example, from an aggregate of multiple powder particles. An aggregate of multiple powder particles is a structure formed by the aggregation of multiple powder particles in contact with each other. Examples of an aggregate of multiple powder particles include structures formed by bonding or joining multiple powder particles together. In this embodiment, the porous structure 3 is a bead aggregate (assembly) formed by joining multiple beads 4 together. That is, the substrate 2 is composed of a bead aggregate (porous structure 3) obtained by joining multiple beads 4 together and molding it into a rectangular plate shape. The porous structure 3 has portions occupied by multiple beads 4 and gaps S between the multiple beads 4.

[0034] In this embodiment, the bead 4 is a glass bead. In this case, the bead assembly is, for example, a sintered body of multiple glass beads (bead 4). In this embodiment, the substrate 2 is entirely composed of a porous structure 3. That is, a porous structure 3 is formed over the entire region of the substrate 2 from the first surface 2a to the second surface 2b. Thus, the porous structure 3 is formed in a manner that connects the first surface 2a and the second surface 2b.

[0035] like Figure 3 As shown, adjacent beads 4 are joined (fused) to each other. Here, substrate 2 has a second step (sample Sa, see reference) capable of implementing the ionization method described later. Figure 4 The rigidity of the substrate 2 (referring to the transfer of the sample Sa) is such that if the rigidity of the substrate 2 is insufficient, the substrate 2 may break 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 the rigidity to withstand the sample Sa (referring to the transfer of the sample Sa). Figure 4 The rigidity of the transfer of the sample Sa (i.e., the operation of pressing the sample Sa onto the first surface 2a and the operation of peeling the sample Sa off the first surface 2a) is (i.e., the rigidity to which the substrate 2 will not break due to the transfer of the sample Sa). In this embodiment, in order to ensure such rigidity, the average diameter of the joint 5 of the adjacent beads 4 (the average diameter d1 of each joint 5) is more than 1 / 10 and less than the average diameter of the beads 4 (the average diameter d2 of each bead 4).

[0036] [Ionization methods and mass analysis methods]

[0037] The ionization method and the mass analysis method using sample support 1 will be described. First, the sample support 1 described above is prepared as the sample support for ionization of the sample (first step). The sample support 1 can be prepared by the practitioner of the ionization method and the mass analysis method, or it can be prepared by the transfer of the sample support 1 by the manufacturer or seller.

[0038] Next, as Figure 4 As shown, sample Sa is transferred onto the first surface 2a of substrate 2 (second step). In Figure 4 In the example, the sample Sa is a slice of fruit (lemon). For example, by pressing the sample Sa onto the first surface 2a of the substrate 2, a portion of the sample Sa is attached to the first surface 2a.

[0039] Next, as Figure 5As shown, a glass slide 6 and a sample support 1 are placed on a stage 21 within the ionization chamber 20 of the mass analysis apparatus 10. Next, charged microdroplets I are irradiated onto a region (hereinafter referred to as the "target region") on the first surface 2a of the substrate 2, containing the area where the transferred sample Sa is located. This ionizes the component Sa1 on the first surface 2a, attracting sample ions Sa2 as the ionized component (third step). In this embodiment, for example, by moving the stage 21 in the X-axis and Y-axis directions, the irradiation area I1 of the charged microdroplets I is moved relative to the target region (i.e., the charged microdroplets I are scanned relative to the target region). The first, second, and third steps described above correspond to an ionization method using the sample support 1 (in this embodiment, desorption electrospray ionization).

[0040] Inside the ionization chamber 20, charged microdroplets I are ejected from the nozzle 22, and sample ions Sa2 are drawn in through the suction port of the ion delivery tube 23. The nozzle 22 has a double-walled structure. Solvent is guided while a high voltage is applied to the inner wall of the nozzle 22. This imparts a biased charge to the solvent reaching the tip of the nozzle 22. Atomizing gas is guided to the outer wall of the nozzle 22. Thus, the solvent is atomized into microdroplets and sprayed, and solvent ions generated during solvent vaporization are ejected as charged microdroplets I.

[0041] Sample ions Sa2 drawn from the suction port of ion delivery tube 23 are transported into the mass analysis chamber 30 through ion delivery tube 23. The mass analysis chamber 30 is maintained in a high vacuum atmosphere (vacuum degree 10). -4 Under conditions of an atmosphere below Torr (where the concentration is below a certain level), sample ions Sa2 are focused by an ion optical system 31 and introduced into a quadrupole mass filter 32 to which a high-frequency voltage is applied. When sample ions Sa2 are introduced into the quadrupole mass filter 32 to which a high-frequency voltage is applied, ions with a mass number determined by the frequency of the high-frequency voltage are selectively allowed to pass through, and the passing ions are detected by a detector 33 (step 4). By scanning the frequency of the high-frequency voltage applied to the quadrupole mass filter 32, the mass number of the ions reaching the detector 33 is changed sequentially, and a mass spectrum of a specified mass range is obtained. In this embodiment, the detector 33 detects ions in a manner corresponding to the position of the irradiation area I1 of the charged microdroplet I, and the two-dimensional distribution of the molecules constituting the sample Sa is visualized. Steps 1, 2, 3, and 4 above correspond to a mass analysis method using the sample support 1.

[0042] [Functions and Effects]

[0043] In the aforementioned sample support 1, the first surface 2a of the substrate 2 is electrically insulating. Therefore, by irradiating the sample Sa transferred to the first surface 2a with charged microdroplets (desorption electrospray ionization), the sample can be appropriately desorbed and ionized. Furthermore, an irregular porous structure 3 with openings on the first surface 2a is formed on the substrate 2. This allows the sample Sa transferred to the first surface 2a to diffuse appropriately into the porous structure 3, thus appropriately adjusting the amount of sample Sa remaining on the first surface 2a. As described above, according to the sample support 1, the composition of the sample Sa can be appropriately ionized.

[0044] Furthermore, the porous structure 3 is a bead assembly (aggregate) formed by bonding multiple beads 4 (powders) together. This allows the components of the sample Sa transferred to the first surface 2a to be appropriately retained on the surface of each bead 4 constituting the bead assembly. Additionally, in this embodiment, the components of the sample Sa can also be appropriately retained on the joints 5 between the beads 4 (e.g., recesses formed by adjacent beads 4).

[0045] Furthermore, the powder constituting the porous structure 3 (beads 4 in this embodiment) is approximately spherical, and the average diameter of the joints 5 of the beads 4 in the bead assembly (the diameter d1 of each joint 5 is referred to as...) Figure 3 The average diameter of bead 4 is the average diameter of bead 4 (the diameter d2 of each bead 4 is referenced). Figure 3 The diameter of the bead 2 is at least 1 / 10 of the average diameter of the bead 4 and less than the average diameter of the bead 4. This ensures the strength of the joint 5 in the bead assembly, and ensures the strength (rigidity) of the substrate capable of withstanding the transfer of the sample Sa relative to the first surface 2a. Furthermore, by ensuring the rigidity of the substrate 2 in this way, it is unnecessary to use frame components or the like to support the substrate 2. Additionally, to ensure the rigidity of the substrate 2, it is not necessary to bond the powder particles together in a manner that satisfies the above conditions. For example, when using ceramic powder (metal oxide) as the powder constituting the porous structure 3, sufficient rigidity of the substrate 2 can be ensured even if the powder particles are not bonded together in a manner that satisfies the above conditions.

[0046] Furthermore, bead 4 is a glass bead. In this case, a substrate 2 having the aforementioned irregular porous structure 3 can be obtained appropriately and inexpensively.

[0047] Furthermore, the porous structure 3 is formed in a manner that connects the first surface 2a and the second surface 2b. In this case, the remaining components of the sample Sa transferred to the first surface 2a can more appropriately escape from the first surface 2a side to the second surface 2b side. As a result, the amount of sample Sa remaining on the first surface 2a can be more appropriately adjusted.

[0048] Furthermore, in the ionization method using the sample support 1 (steps 1 to 3), since the first surface 2a of the substrate 2 of the sample support 1 is an electrically insulating component, even if, for example, a nozzle 22, a micro-droplet irradiation section to which a high voltage is applied, is brought close to the first surface 2a, the generation of discharge between the nozzle 22 and the sample support 1 can be suppressed. Additionally, as described above, because the substrate 2 has an irregular porous structure 3, the amount of sample Sa remaining on the first surface 2a can be appropriately adjusted. Therefore, according to this ionization method, by bringing the nozzle 22 close to the first surface 2a and irradiating the first surface 2a with charged micro-droplets, the components of the sample Sa transferred to the first surface 2a can be appropriately ionized.

[0049] Furthermore, the porous structure 3 is a bead assembly formed by joining multiple beads 4 together, and in the second step, the composition of the sample Sa is retained on the surface of the beads 4. Thus, the sample Sa transferred to the first surface 2a can be appropriately retained on the surface of the bead assembly (porous structure 3). As a result, in the third step, the composition of the sample Sa can be appropriately ionized. Moreover, as described above, in this embodiment, the composition of the sample Sa can also be appropriately retained at the joints 5 where the beads 4 meet.

[0050] Furthermore, in the aforementioned ionization method, in the third step, the irradiation area I1 of the charged microdroplet I is moved relative to the first surface. The positional information (two-dimensional distribution information of the molecules constituting the sample Sa) of the sample Sa remaining on the first surface 2a side of the substrate 2 is maintained. Therefore, by moving the irradiation area I1 of the charged microdroplet I relative to the first surface 2a (target area), the components of the sample Sa can be ionized while maintaining the positional information of the sample Sa. Thus, in the later step of detecting the sample ion Sa2, the two-dimensional distribution of the molecules constituting the sample Sa can be imaged. Moreover, as described above, since the nozzle 22 can be brought closer to the first surface 2a, the expansion of the irradiation area I1 of the charged microdroplet I can be suppressed. Therefore, in the later step of detecting the sample ion Sa2, the two-dimensional distribution of the molecules constituting the sample Sa can be imaged at high resolution.

[0051] Furthermore, in the mass analysis method using the sample support 1, as described above, the components of the sample Sa are appropriately ionized by irradiation with charged micro-droplets I, thus enabling an increase in the signal intensity when detecting sample ions Sa2.

[0052] [Variation Example]

[0053] The present invention is not limited to the embodiments described above. For example, in the above embodiments, the sample support 1 is constructed to include only the substrate 2, but the sample support 1 may also include components other than the substrate 2. For example, a support member (frame, etc.) for supporting the substrate 2 may be provided on a part of the substrate 2 (e.g., a corner).

[0054] Furthermore, the sample Sa is not limited to a slice of fruit (lemon) exemplified in the above embodiments. The sample Sa may have a flat surface or a surface with irregularities. In addition, the sample Sa may be a substance other than fruit, such as a plant leaf. In this case, by transferring the components of the leaf surface, which serves as the sample Sa, onto the first surface 2a, imaging quality analysis of the leaf surface (veins) can be performed.

[0055] Furthermore, in the above embodiment, the entire substrate 2 is composed of a porous structure 3 as an assembly of beads, but the porous structure 3 may also be formed on a portion of the substrate 2. For example, the porous structure 3 may be formed only in the central region of the substrate 2 (a portion of the first surface 2a) defined as the measurement area for transferring the sample Sa, or it may not be formed on other parts of the substrate 2. Additionally, the porous structure 3 may not cover the entire area from the first surface 2a to the second surface 2b. That is, the porous structure 3 may be open only at least on the first surface 2a, or it may not be open on the second surface 2b. For example, the substrate 2 may also be composed of a flat plate and a porous structure disposed on the plate. As an example, the substrate 2 may also be composed of a glass plate and an assembly of glass beads (a porous structure) disposed on the glass plate.

[0056] Furthermore, in the above embodiment, the substrate 2 is formed of an insulating material, thereby making the first surface 2a electrically insulating. However, the substrate 2 can also be formed of a conductive material. In this case, the first surface 2a can also be electrically insulating by applying an electrically insulating coating to it. By applying such an insulating coating, the first surface 2a of the substrate 2 can be made electrically insulating, so a substrate 2 formed of a conductive material can be used. For example, in this case, the porous structure 3 can also be formed by an aggregate of multiple powders made of metal. Thus, by providing an electrically insulating coating, the freedom of choice in selecting the substrate material can be increased.

[0057] Furthermore, the materials used to form the porous structure 3 can include, for example, glass, metal oxides (such as alumina), or metals with an insulating coating. Additionally, the powder forming the porous structure 3 is not limited to approximately spherical beads, but can also have shapes other than approximately spherical.

[0058] Explanation of symbols

[0059] 1…sample support, 2…substrate, 2a…first surface, 2b…second surface, 3…porous structure, 4…bead (powder), 5…bonding part, Sa…sample, Sa2…sample ions (ionized components).

Claims

1. A sample support, wherein, It is a sample support used for the ionization of the sample. The substrate comprises: a first surface having electrical insulation, which is pressed and transferred onto the sample; a second surface opposite to the first surface; and an irregular porous structure with openings at least on the first surface. The porous structure is formed by an aggregate of multiple powder particles. The powder is composed of glass, metal oxide, or metal with an insulating coating. The average diameter of the junction between adjacent powder particles is more than 1 / 10 of the average diameter of the powder particles but less than the average diameter of the powder particles.

2. The specimen support as described in claim 1, wherein, An electrically insulating coating is applied to the first surface.

3. The specimen support as described in claim 1, wherein, The porous structure is formed by an aggregate of multiple powders made of metal.

4. The specimen support as described in claim 1, wherein, The powder is glass beads.

5. The specimen support as described in any one of claims 1 to 4, wherein, The porous structure is formed in a manner that connects the first surface and the second surface.

6. An ionization method, wherein, include: A first step of preparing a sample support having a substrate, the substrate having: a first surface having electrical insulation, a second surface opposite to the first surface, and an irregular porous structure with an opening at least on the first surface; The second step involves transferring the sample by pressing it onto the first surface; and The third step involves ionizing the components of the transferred sample by irradiating the first surface with charged microdroplets, and attracting the ionized components. The porous structure is formed by an aggregate of multiple powder particles. The powder is composed of glass, metal oxide, or metal with an insulating coating. The average diameter of the junction between adjacent powder particles is more than 1 / 10 of the average diameter of the powder particles but less than the average diameter of the powder particles.

7. The ionization method as described in claim 6, wherein, In the second step, the composition of the sample is maintained on the surface of the powder.

8. The ionization method as described in claim 6 or 7, wherein, In the third step, the irradiation area of ​​the charged microdroplets is moved relative to the first surface.

9. A quality analysis method, in, include: The first step, the second step, and the third step of the ionization method according to any one of claims 6 to 8; and A fourth step involves detecting the component that was ionized in the third step.

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