Patent Publication Number: US-2022223396-A1

Title: Sample support, adapter, ionization method and mass spectrometry method

Description:
TECHNICAL FIELD 
     The present disclosure relates to a sample support, an adapter, an ionization method, and a mass spectrometry method. 
     BACKGROUND ART 
     Conventionally, a laser desorption/ionization method is known as a method of ionizing a sample such as a biological sample to perform mass spectrometry or the like. As a sample support used in a laser desorption/ionization method, Patent Literature 1 describes one including a substrate in which a plurality of through-holes are formed and a conductive layer provided on at least one surface of the substrate. 
     CITATION LIST 
     Patent Literature 
     
         
         [Patent Literature 1] Japanese Patent No. 6093492 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     When a sample support as described above is mounted on a mass spectrometer, an adapter having a reference surface positioned on the same plane as a focal point of an energy beam such as a laser beam may be used in the mass spectrometer. In such a case, when a focal point of an energy beam is aligned with a conductive layer provided on one surface of the substrate with high accuracy, sensitivity and resolution are improved in detection of components of the ionized sample. 
     Therefore, an objective of the present disclosure is to provide a sample support, an adapter, an ionization method, and a mass spectrometry method that enable highly accurate positioning of a focal point of an energy beam in a mass spectrometer. 
     Solution to Problem 
     A sample support of one aspect of the present disclosure is a sample support used for ionization of a sample and includes a film part having a first front surface and a first back surface, the film part being formed with a plurality of through-holes opening to the first front surface and the first back surface, and a support part defining a measurement region for ionizing the sample with respect to the film part and supporting the film part, in which the support part includes an inner portion having a second front surface and a second back surface, the film part being fixed to the inner portion, and an outer portion having a third front surface and a third back surface and extending along an outer edge of the inner portion, and a difference generated between a position of the first front surface and a position of the third front surface in a thickness direction of the film part is smaller than a thickness of the film part. 
     In the sample support, a difference generated between a position of the first front surface of the film part and a position of the third front surface of the outer portion in the thickness direction of the film part is smaller than the thickness of the film part. Thereby, when the sample support is mounted on a mass spectrometer using an adapter having a reference surface positioned on the same plane as a focal point of an energy beam such as a laser beam in the mass spectrometer, the focal point of the energy beam can be aligned with the first front surface of the film part at a lower level than the thickness of the film part by causing the adapter to hold the outer portion so that the reference surface of the adapter and the third front surface of the outer portion are positioned on the same plane. Therefore, the sample support enables highly accurate positioning of a focal point of the energy beam in the mass spectrometer. 
     In the sample support of one aspect of the present disclosure, the first front surface and the third front surface may be positioned on the same plane. Thereby, a focal point of the energy beam can be more accurately aligned with the first front surface of the film part in the mass spectrometer. 
     In the sample support of one aspect of the present disclosure, the second back surface may be positioned on a side on which the first front surface faces in the thickness direction with respect to the third back surface, and the film part may be fixed to the second back surface. Thereby, a configuration in which a focal point of the energy beam can be aligned with the first front surface of the film part with high accuracy can be realized with a simple structure. 
     In the sample support of one aspect of the present disclosure, the second front surface may be positioned on a side on which the first back surface faces in the thickness direction with respect to the third front surface, and the film part may be fixed to the second front surface. Thereby, a configuration in which a focal point of the energy beam can be aligned with the first front surface of the film part with high accuracy can be realized with a simple structure. 
     In the sample support of one aspect of the present disclosure, the film part may include a substrate formed of an insulating material, and a conductive layer provided at least on the first front surface side with respect to the substrate at least in the measurement region. Thereby, components of the sample can be efficiently ionized in the mass spectrometer. 
     In the sample support of one aspect of the present disclosure, a width of each of the plurality of through-holes may be 1 to 700 nm. Thereby, components of the sample can be appropriately retained on the first front surface of the film part. 
     In the sample support of one aspect of the present disclosure, the support part may define a plurality of measurement regions, each of the plurality of measurement regions being the measurement region. Thereby, the sample can be analyzed for each measurement region in the mass spectrometer. 
     An adapter of one aspect of the present disclosure is an adapter used for mounting the above-described sample support on a mass spectrometer and includes a holding part having a reference surface positioned on the same plane as a focal point of an energy beam in the mass spectrometer and configured to hold the outer portion so that the reference surface and the third front surface are positioned on the same plane. 
     According to the adapter, a focal point of the energy beam can be aligned with the first front surface of the film part with high accuracy in the mass spectrometer. 
     The adapter of one aspect of the present disclosure may further include a mount part configured to be held by the holding part together with the outer portion in a state in which the mount part is in contact with the first back surface. Thereby, since the film part can be stably supported, a focal point of the energy beam can be more accurately aligned with the first front surface of the film part in the mass spectrometer. 
     An ionization method of one aspect of the present disclosure includes a step of preparing the above-described sample support, a step of disposing the sample in the measurement region, a step of mounting the sample support on a mass spectrometer using an adapter including a holding part having a reference surface positioned on the same plane as a focal point of an energy beam in the mass spectrometer and configured to hold the outer portion so that the reference surface and the third front surface are positioned on the same plane, and a step of ionizing components of the sample by irradiating the measurement region with an energy beam. 
     According to the ionization method, components of the sample can be ionized with a focal point of the energy beam aligned with the first front surface of the film part with high accuracy. 
     A mass spectrometry method of one aspect of the present disclosure includes a plurality of steps included in the above-described ionization method, and a step of detecting the ionized components. 
     In the mass spectrometry method, since components of the sample are ionized with the focal point of the energy beam aligned with the first front surface of the film part with high accuracy, sensitivity and resolution can be improved in detection of the ionized components. 
     Advantageous Effects of Invention 
     According to the present disclosure, it is possible to provide a sample support, an adapter, an ionization method, and a mass spectrometry method that enable highly accurate positioning of a focal point of an energy beam in a mass spectrometer. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view of a sample support of a first embodiment. 
         FIG. 2  is a cross-sectional view along line II-II illustrated in  FIG. 1 . 
         FIG. 3  is a view showing an SEM image of a surface of a substrate illustrated in  FIG. 1 . 
         FIG. 4  is a plan view of the sample support and an adapter of the first embodiment. 
         FIG. 5  is a cross-sectional view along line V-V illustrated in  FIG. 4 . 
         FIG. 6  is a view illustrating a mass spectrometry method of the first embodiment. 
         FIG. 7  is a cross-sectional view of a part of a sample support of a second embodiment. 
         FIG. 8  is a cross-sectional view of a part of a sample support of a modified example. 
         FIG. 9  is a plan view of the sample support of the modified example. 
         FIG. 10  is a cross-sectional view along line X-X illustrated in  FIG. 9 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each of the drawings, the same or corresponding portions are denoted by the same reference signs, and duplicate descriptions thereof will be omitted. 
     First Embodiment 
     [Configuration of Sample Support] 
     A sample support  1 A illustrated in  FIGS. 1 and 2  is used for ionization of a sample. The sample support  1 A includes a substrate  2 , a frame  3 , and a conductive layer  4 . The substrate  2  includes a surface  2   a  and a back surface  2   b  (a surface on a side opposite to the surface  2   a ). A plurality of through-holes  2   c  that open to the surface  2   a  and the back surface  2   b  are formed in the substrate  2 . Each of the through-holes  2   c  extends in a thickness direction D of the substrate  2  (hereinafter, simply referred to as “direction D”). The direction D is a direction in which the surface  2   a  and the back surface  2   b  face each other. 
     The substrate  2  is formed of, for example, an insulating material in a rectangular plate shape. A length of one side of the substrate  2  when viewed in the direction D is, for example, about several centimeters, and a thickness of the substrate  2  is, for example, 1 to 50 μm. A shape of each through-hole  2   c  when viewed in the direction D is, for example, substantially circular, and a width of each through-hole  2   c  is, for example, 1 to 700 nm. The plurality of through-holes  2   c  each having a substantially constant width are uniformly formed (with a uniform distribution) in the substrate  2 . An aperture ratio of the through-holes  2   c  in a measurement region R (a proportion occupied by all the through-holes  2   c  to the measurement region R when viewed in the direction D) is in a range of 10% to 80% in view of practical use, and particularly preferably in a range of 60 to 80%. Further, in the plurality of through-holes  2   c , widths of the through-holes  2   c  may not all be uniform, or the through-holes  2   c  may be partially connected to each other. 
     The width of the through-hole  2   c  is a value obtained as follows. First, images of the surface  2   a  and the back surface  2   b  of the substrate  2  are acquired.  FIG. 3  is a view showing an SEM image of the surface  2   a  of the substrate  2 . In the SEM image, black portions are the through-holes  2   c , and white portions are partition wall portions between the through-holes  2   c . Next, a plurality of pixel groups corresponding to a plurality of first openings (openings on the surface  2   a  side of the through-holes  2   c ) in the measurement region R (to be described later) are extracted by performing, for example, binarization processing on the acquired image of the surface  2   a , and a diameter of a circle having an average area of the first openings is obtained on the basis of a size per pixel. Similarly, a plurality of pixel groups corresponding to a plurality of second openings (openings on the back surface  2   b  side of the through-holes  2   c ) in the measurement region R are extracted by performing, for example, binarization processing on the acquired image of the back surface  2   b , and a diameter of a circle having an average area of the second openings is obtained on the basis of a size per pixel. Then, an average value of the diameter of the circle acquired for the surface  2   a  and the diameter of the circle acquired for the back surface  2   b  is acquired as a width of the through-hole  2   c.    
     The substrate  2  illustrated in  FIG. 3  is an alumina porous film formed by anodizing aluminum (Al). Specifically, the substrate  2  can be obtained by subjecting the Al substrate to an anodizing treatment and peeling an oxidized surface portion from the Al substrate. Further, the substrate  2  may be formed by anodizing a valve metal other than Al such as tantalum (Ta), niobium (Nb), titanium (Ti), hafnium (Hf), zirconium (Zr), zinc (Zn), tungsten (W), bismuth (Bi), antimony (Sb), or the like, or may be formed by anodizing silicon (Si). 
     As illustrated in  FIGS. 1 and 2 , the frame  3  is fixed to the surface  2   a  of the substrate  2  by an adhesive layer (not illustrated). As a material of the adhesive layer, an adhesive material (for example, a low melting point glass, an adhesive for vacuum, or the like) having little discharge gas is preferably used. The frame  3  is formed in a rectangular plate shape using, for example, a material having the same coefficient of thermal expansion as a material of the substrate  2  or a material having a coefficient of thermal expansion lower than that of the material of the substrate  2  (for example, an iron-nickel alloy ( 42  alloy), molybdenum, Kovar, titanium, or the like when the material of the substrate  2  is alumina). A length of one side of the frame  3  when viewed in the direction D is, for example, about several centimeters, and a thickness of the frame  3  is, for example, 1 mm or less. When viewed from the direction D, an outer edge of the frame  3  is positioned on an outer side of an outer edge of the substrate  2 . A plurality of openings disposed two-dimensionally (for example, in a matrix form such as 3 rows and 5 columns) are formed in the frame  3 . A portion of the substrate  2  corresponding to each of the openings of the frame  3  functions as the measurement region R for ionizing a sample. A shape of each opening when viewed in the direction D is, for example, a circle, and a diameter of each opening in that case is, for example, about several millimeters to tens of millimeters. Further, when a material having the same coefficient of thermal expansion as the material of the substrate  2  or a material having a coefficient of thermal expansion lower than that of the material of the substrate  2  is used for the frame  3 , the substrate  2  can be prevented from bending after bonding and calcining, and sufficient adhesion between the substrate  2  and a sample S and improvement in sensitivity can be realized in mass spectrometry. When the substrate  2  and the frame  3  on which the conductive layer  4  is formed are calcined during manufacture of the sample support  1 A, crystallinity of the conductive layer  4  can be improved, and a sample support more suitable for mass spectrometry can be obtained. 
     The conductive layer  4  is continuously (integrally) formed in a region of the surface  2   a  of the substrate  2  corresponding to each opening of the frame  3  (that is, a region of the surface  2   a  of the substrate  2  corresponding to each measurement region R), an inner surface of each opening, and a surface of the frame  3  on a side on which the surface  2   a  faces in the direction D. The conductive layer  4  covers a region of the surface  2   a  of the substrate  2  in which the plurality of through-holes  2   c  are not formed in each measurement region R. The conductive layer  4  is formed of a conductive material. However, as a material of the conductive layer  4 , for the reason to be described below, a metal having a low affinity (reactivity) with a sample and high conductivity is preferably used. 
     When the conductive layer  4  is formed of, for example, a metal such as copper (Cu) that has a high affinity with a sample such as a protein, the sample is ionized in a state in which Cu atoms are attached to sample molecules in the process of ionizing the sample, and there is a likelihood that a detection result thereof will deviate in the mass spectrometry method according to an amount of the attached Cu atoms. Therefore, as the material of the conductive layer  4 , a metal having a low affinity with a sample is preferably used. 
     On the other hand, a metal having higher conductivity tends to apply a constant voltage easily and stably. Therefore, when the conductive layer  4  is formed of a metal having high conductivity, a voltage can be uniformly applied to the surface  2   a  of the substrate  2  in the measurement region R. Also, a metal having higher conductivity also shows a tendency to have higher thermal conductivity. Therefore, when the conductive layer  4  is formed of a metal having high conductivity, energy of a laser beam irradiated to the substrate  2  can be efficiently transmitted to the sample via the conductive layer  4 . Therefore, as the material of the conductive layer  4 , a metal having high conductivity is preferably used. 
     From the above viewpoint, for example, gold (Au), platinum (Pt), or the like is preferably used as the material of the conductive layer  4 . The conductive layer  4  is formed at a thickness of about 1 nm to 350 nm using, for example, a plating method, an atomic layer deposition (ALD) method, a vapor deposition method, a sputtering method, or the like. Further, as the material of the conductive layer  4 , for example, chromium (Cr), nickel (Ni), titanium (Ti), or the like may also be used. 
     In the above sample support  1 A, a film part  20  and a support part  30  are constituted. The film part  20  is constituted by the substrate  2 , and the conductive layer  4  formed in a region of the surface  2   a  of the substrate  2  corresponding to each measurement region R. The support part  30  is constituted by the frame  3 , and the conductive layer  4  formed on a surface of the frame  3  on a side on which the surface  2   a  faces in the direction D. 
     The film part  20  includes a first front surface  20   a  and a first back surface  20   b  (a surface on a side opposite to the first front surface  20   a ). In the present embodiment, the first front surface  20   a  is a surface of the conductive layer  4  on a side opposite to the substrate  2 , and the first back surface  20   b  is the back surface  2   b  of the substrate  2 . A plurality of through-holes  20   c  that open to the first front surface  20   a  and the first back surface  20   b  are formed in the film part  20 . Each of the through-holes  20   c  corresponds to the through-hole  2   c  formed in the substrate  2 . Therefore, a width of each through-hole  20   c  is, for example, 1 to 700 nm, and the width of the through-hole  20   c  is a value obtained through the same method as that of the through-hole  2   c . Further, illustration of the plurality of through-holes  20   c  is omitted in  FIG. 1 . 
     The support part  30  defines a plurality of measurement regions R with respect to the film part  20  and supports the film part  20 . The support part  30  includes an inner portion  31  and an outer portion  32 . The inner portion  31  is a portion to which the film part  20  is fixed. When viewed in the direction D, an outer edge  31   c  of the inner portion  31  coincides with, for example, an outer edge of the substrate  2 . The outer portion  32  extends along the outer edge  31   c  of the inner portion  31 . In the present embodiment, an intermediate portion  33  is provided between the inner portion  31  and the outer portion  32 , but the intermediate portion  33  may not be provided between the inner portion  31  and the outer portion  32  (that is, the inner portion  31  and the outer portion  32  may be directly connected). 
     The inner portion  31  has a second front surface  31   a  and a second back surface  31   b  (a surface on a side opposite to the second front surface  31   a ). In the present embodiment, the second back surface  31   b  is a surface of the frame  3  on a side opposite to the conductive layer  4  in the direction D, and the second front surface  31   a  is a surface of the conductive layer  4  on a side opposite to the second back surface  31   b  in the direction D. That is, the second front surface  31   a  is a surface of the conductive layer  4  on a side opposite to the frame  3 , and the second back surface  31   b  is a surface of the frame  3  on a side opposite to the conductive layer  4 . The outer portion  32  has a third front surface  32   a  and a third back surface  32   b  (a surface on a side opposite to the third front surface  32   a ). In the present embodiment, the third back surface  32   b  is a surface of the frame  3  on a side opposite to the conductive layer  4  in the direction D, and the third front surface  32   a  is a surface of the conductive layer  4  on a side opposite to the third back surface  32   b  in the direction D. That is, the third front surface  32   a  is a surface of the conductive layer  4  on a side opposite to the frame  3 , and the third back surface  32   b  is a surface of the frame  3  on a side opposite to the conductive layer  4 . 
     The first front surface  20   a  of the film part  20  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane (the same plane perpendicular to the direction D). That is, a difference generated between a position of the first front surface  20   a  of the film part  20  and a position of the third front surface  32   a  of the outer portion  32  in the direction D (a direction that coincides with a thickness direction of the film part  20  (a direction in which the first front surface  20   a  and the first back surface  20   b  face each other)) is zero in the present embodiment and is smaller than the thickness of the film part  20 . 
     The second back surface  31   b  of the inner portion  31  is positioned on a side (upper side in  FIG. 2 ) on which the first front surface  20   a  of the film part  20  faces in the direction D with respect to the third back surface  32   b  of the outer portion  32 . The film part  20  (specifically, the surface  2   a  of the substrate  2 ) is fixed to the second back surface  31   b  of the inner portion  31  by the adhesive layer (not illustrated) described above. In the present embodiment, the substrate  2  is disposed in a recessed part having the second back surface  31   b  of the inner portion  31  as a bottom surface and surrounded by the intermediate portion  33 . 
     [Configuration of Adapter] 
     An adapter  10  illustrated in  FIGS. 4 and 5  is used for mounting the above-described sample support  1 A on a mass spectrometer. The adapter  10  includes a holding part  11 . The holding part  11  includes a main body member  12 , a plurality of stoppers  13 , and a plurality of sets of washers  14  and bolts  15 . The main body member  12  is formed in a rectangular frame shape by, for example, a metal material. The plurality of stoppers  13  are provided on the main body member  12  to protrude inward of the main body member  12 . The plurality of sets of washers  14  and bolts  15  can be detachably attached to one surface  12   a  of the main body member  12 . In a state in which the plurality of sets of washers  14  and bolts  15  are fixed to the surface  12   a  of the main body member  12 , a part of each washer  14  and each stopper  13  face each other via a predetermined distance in the direction D. The holding part  11  has a reference surface  11   a  positioned on the same plane as a focal point of a laser beam (the same plane parallel to an optical axis of the laser beam) in the mass spectrometer. In the present embodiment, the reference surface  11   a  is the surface  12   a  of the main body member  12 . 
     The adapter  10  further includes a mount part  16 . The mount part  16  is formed, for example, in a rectangular plate shape by a metal material. The mount part  16  in contact with the first back surface  20   b  of the film part  20  of the sample support  1 A is held by the holding part  11  together with the outer portion  32  of the sample support  1 A. Specifically, the mount part  16  includes a contact portion  17  and a held portion  18 . The held portion  18  extends along an outer edge of the contact portion  17 . The contact portion  17  is in contact with the first back surface  20   b  of the film part  20  in the recessed part having the second back surface  31   b  of the inner portion  31  as a bottom surface and surrounded by the intermediate portion  33 . The held portion  18  is in contact with the third back surface  32   b  of the outer portion  32  and is held by the holding part  11  together with the outer portion  32 . In the present embodiment, a thickness of the outer portion  32  and the held portion  18  in the direction D is substantially equal to the predetermined distance between a part of each washer  14  and each stopper  13 . 
     The sample support  1 A is disposed on the plurality of stoppers  13  via the mount part  16 , the plurality of sets of washers  14  and bolts  15  are fixed to the surface  12   a  of the main body member  12  in that state, and thereby the sample support  1 A is held by the holding part  11  together with the mount part  16 . In a state in which the sample support  1 A is held by the holding part  11 , the reference surface  11   a  of the holding part  11  and the third front surface  32   a  of the outer portion  32  are on the same plane (the same plane parallel to the direction D and the optical axis of the laser beam). That is, the holding part  11  holds the outer portion  32  so that the reference surface  11   a  of the holding part  11  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. 
     [Ionization Method and Mass Spectrometry Method] 
     An ionization method and a mass spectrometry method using the sample support  1 A and the adapter  10  described above will be described with reference to  FIG. 6 . First, the sample support  1 A is prepared (preparation step). Next, the sample S is disposed in each measurement region R of the sample support  1 A (disposition step). In the present embodiment, for example, a solution containing the sample S is dropped onto each measurement region R. Thereby, in each measurement region R, a surplus solution permeates through the plurality of through-holes  20   c , and components S 1  of the sample S is appropriately retained on the conductive layer  4  (that is, on the first front surface  20   a  of the film part  20 ). Next, the sample support  1 A in which the sample S is disposed in each measurement region R is mounted on a mass spectrometer  100  using the adapter  10  (mounting step). 
     Next, a laser beam irradiation part  102  of the mass spectrometer  100  is operated to irradiate each measurement region R with a laser beam (an energy beam) L while operating a voltage application part  101  of the mass spectrometer  100  to apply a voltage to the conductive layer  4  of the sample support  1 A via the adapter  10 . Thereby, the components S 1  of the sample S are ionized (ionization step). At this time, since a focal point P of the laser beam L and the reference surface  11   a  of the holding part  11  are positioned on the same plane, the reference surface  11   a  of the holding part  11  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane, and the third front surface  32   a  of the outer portion  32  and the first front surface  20   a  of the film part  20  are positioned on the same plane, the focal point P of the laser beam L is positioned on the first front surface  20   a  of the film part  20  in which the components S 1  of the sample S are retained. The above steps correspond to the ionization method using the sample support  1 A and the adapter  10  (in the present embodiment, a laser desorption/ionization method). 
     Next, sample ions S 2  (ionized components S 1 ) discharged due to ionization of the components S 1  of the sample S are detected by an ion detector  103  of the mass spectrometer  100  (detection step). Specifically, the discharged sample ions S 2  move while being accelerated toward a ground electrode (not illustrated) provided between the sample support  1 A and the ion detector  103  due to an electric potential difference generated between the conductive layer  4  to which a voltage is applied and the ground electrode, and thereby are detected by the ion detector  103 . In the present embodiment, the mass spectrometer  100  is a scanning mass spectrometer using time-of-flight mass spectrometry (TOF-MS). The above steps correspond to the mass spectrometry method using the sample support  1 A and the adapter  10 . 
     [Operation and Effects] 
     As described above, the first front surface  20   a  of the film part  20  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane in the sample support  1 A. That is, a difference generated between a position of the first front surface  20   a  of the film part  20  and a position of the third front surface  32   a  of the outer portion  32  in the direction D is zero and is smaller than the thickness of the film part  20 . Thereby, when the sample support  1 A is mounted on the mass spectrometer  100  using the adapter  10  having the reference surface  11   a  positioned on the same plane as the focal point P of the laser beam L in the mass spectrometer  100 , the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  with higher accuracy by causing the adapter  10  to hold the outer portion  32  so that the reference surface  11   a  of the adapter  10  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. Therefore, the sample support  1 A enables highly accurate positioning of the focal point P of the laser beam L in the mass spectrometer  100 . 
     Also, according to the sample support  1 A, since it can be attached to the adapter  10  without using a tape or the like, convenience of a user is further enhanced. Moreover, for example, when a similar sample support is fixed on a slide glass with a tape or the like, positioning is required each time, but according to the sample support  1 A, such positioning is not necessary. 
     Also, in the sample support  1 A, the second back surface  31   b  of the inner portion  31  is positioned on a side on which the first front surface  20   a  of the film part  20  faces in the direction D with respect to the third back surface  32   b  of the outer portion  32 , and the film part  20  is fixed to the second back surface  31   b  of the inner portion  31 . Thereby, a configuration in which the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  with high accuracy can be realized with a simple structure. 
     Also, in the sample support  1 A, the film part  20  includes the substrate  2  formed of an insulating material and the conductive layer  4  provided on the first front surface  20   a  side of the substrate  2  in each measurement region R. Thereby, the components S 1  of the sample S can be efficiently ionized in the mass spectrometer  100 . 
     Also, in the sample support  1 A, the width of each of the plurality of through-holes  20   c  is 1 to 700 nm. Thereby, the components S 1  of the sample S can be appropriately retained on the first front surface  20   a  of the film part  20 . 
     Also, the support part  30  defines the plurality of measurement regions R in the sample support  1 A. Thereby, the sample S can be analyzed for each measurement region R in the mass spectrometer  100 . 
     Also, in the adapter  10 , the holding part  11  has the reference surface  11   a  positioned on the same plane as the focal point P of the laser beam L in the mass spectrometer  100  and holds the outer portion  32  of the sample support  1 A so that the reference surface  11   a  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. Thereby, the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  with high accuracy in the mass spectrometer  100 . 
     Also, in the adapter  10 , the mount part  16  in contact with the first back surface  20   b  of the film part  20  is held by the holding part  11  together with the outer portion  32 . Thereby, since the film part  20  can be stably supported, the focal point P of the laser beam L can be more accurately aligned with the first front surface  20   a  of the film part  20  in the mass spectrometer  100 . 
     Also, according to the ionization method using the sample support  1 A and the adapter  10 , the components S 1  of the sample S can be ionized with the focal point P of the laser beam L aligned with the first front surface  20   a  of the film part  20  with high accuracy. 
     Also, in the mass spectrometry method using the sample support  1 A and the adapter  10 , since the components S 1  of the sample S are ionized with the focal point P of the laser beam L aligned with the first front surface  20   a  of the film part  20  with high accuracy, sensitivity and resolution can be improved in detection of the sample ions S 2 . 
     Second Embodiment 
     As illustrated in  FIG. 7 , a sample support  1 B is mainly different in a configuration of a support part  30  from the above-described sample support  1 A. That is, in the sample support  1 B, a second front surface  31   a  of an inner portion  31  is positioned on a side on which a first back surface  20   b  of a film part  20  faces in a direction D (on a lower side in  FIG. 7 ) with respect to a third front surface  32   a  of an outer portion  32 . The film part  20  (specifically, a back surface  2   b  of the substrate  2 ) is fixed to the second front surface  31   a  of the inner portion  31  by an adhesive layer (not illustrated) described above. In the present embodiment, the substrate  2  is disposed in a recessed part having the second front surface  31   a  of the inner portion  31  as a bottom surface and surrounded by an intermediate portion  33 . Further, the sample support  1 B can also be mounted on a mass spectrometer  100  using an adapter  10  as in the sample support  1 A described above. Then, an ionization method and a mass spectrometry method using the sample support  1 B and the adapter  10  can be performed as in the first embodiment. 
     In the sample support  1 B configured as described above, a first front surface  20   a  of the film part  20  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. That is, a difference generated between a position of the first front surface  20   a  of the film part  20  and a position of the third front surface  32   a  of the outer portion  32  in the direction D is zero and is smaller than a thickness of the film part  20 . Thereby, when the sample support  1 B is mounted on the mass spectrometer  100  using the adapter  10  having a reference surface  11   a  positioned on the same plane as a focal point P of a laser beam L in the mass spectrometer  100 , the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  with higher accuracy by causing the adapter  10  to hold the outer portion  32  so that the reference surface  11   a  of the adapter  10  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. Therefore, the sample support  1 B enables highly accurate positioning of the focal point P of the laser beam L in the mass spectrometer  100 . 
     Also, according to the sample support  1 B, since it can be attached to the adapter  10  without using a tape or the like, convenience of a user is further enhanced. Moreover, for example, when a similar sample support is fixed on a slide glass with a tape or the like, positioning is required each time, but according to the sample support  1 B, such positioning is not necessary. 
     Also, in the sample support  1 B, the second front surface  31   a  of the inner portion  31  is positioned on a side on which the first back surface  20   b  of the film part  20  faces in the direction D with respect to the third front surface  32   a  of the outer portion  32 , and the film part  20  is fixed to the second front surface  31   a  of the inner portion  31 . Thereby, a configuration in which the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  with high accuracy can be realized with a simple structure. 
     Also, in the sample support  1 B, the film part  20  includes the substrate  2  formed of an insulating material and a conductive layer  4  provided on the first front surface  20   a  side of the substrate  2  in each measurement region R. Thereby, components S 1  of a sample S can be efficiently ionized in the mass spectrometer  100 . 
     Also, a width of each of a plurality of through-holes  20   c  is 1 to 700 nm in the sample support  1 B. Thereby, the components S 1  of the sample S can be appropriately retained on the first front surface  20   a  of the film part  20 . 
     Also, the support part  30  defines the plurality of measurement regions R in the sample support  1 B. Thereby, the sample S can be analyzed for each measurement region R in the mass spectrometer  100 . 
     Also, in the adapter  10 , a holding part  11  has the reference surface  11   a  positioned on the same plane as the focal point P of the laser beam L in the mass spectrometer  100  and holds the outer portion  32  of the sample support  1 B so that the reference surface  11   a  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. Thereby, the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  with high accuracy in the mass spectrometer  100 . 
     Also, in the adapter  10 , a mount part  16  in contact with the first back surface  20   b  of the film part  20  is held by the holding part  11  together with the outer portion  32 . Thereby, since the film part  20  can be stably supported, the focal point P of the laser beam L can be more accurately aligned with the first front surface  20   a  of the film part  20  in the mass spectrometer  100 . 
     Also, according to the ionization method using the sample support  1 B and the adapter  10 , the components S 1  of the sample S can be ionized with the focal point P of the laser beam L aligned with the first front surface  20   a  of the film part  20  with high accuracy. 
     Also, in the mass spectrometry method using the sample support  1 B and the adapter  10 , since the components S 1  of the sample S are ionized with the focal point P of the laser beam L aligned with the first front surface  20   a  of the film part  20  with high accuracy, sensitivity and resolution can be improved in detection of sample ions S 2 . 
     Modified Example 
     As illustrated in (a) and (b) of  FIG. 8 , in each of the sample support  1 A and the sample support  1 B, a thickness of the outer portion  32  in the direction D may be substantially equal to a predetermined distance between a part of each washer  14  and each stopper  13 . In these cases, each of the sample support  1 A and the sample support  1 B can be attached to the adapter  10  without using the mount part  16 . 
     Also, in each of the sample support  1 A and the sample support  1 B, if a difference generated between a position of the first front surface  20   a  of the film part  20  and a position of the third front surface  32   a  of the outer portion  32  in the direction D is smaller than a thickness of the film part  20 , the first front surface  20   a  of the film part  20  and the third front surface  32   a  of the outer portion  32  may not be positioned on the same plane perpendicular to the direction D. Also in this case, when the adapter  10  is caused to hold the outer portion  32  of the support part  30  so that the reference surface  11   a  of the adapter  10  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane, the focal point P of the laser beam L can be aligned with the first front surface  20   a  of the film part  20  at a lower level than the thickness of the film part  20 . 
     Also, the holding part  11  of the adapter  10  is not limited to the above-described configuration (that is, the configuration including the main body member  12 , the plurality of stoppers  13 , and the plurality of sets of washers  14  and bolts  15 ) as long as it can hold the outer portion  32  so that the reference surface  11   a  of the adapter  10  and the third front surface  32   a  of the outer portion  32  are positioned on the same plane. 
     Also, in each of the sample support  1 A and the sample support  1 B, the conductive layer  4  may be provided at least on the surface  2   a  of the substrate  2 . That is, when the conductive layer  4  is provided on the surface  2   a  of the substrate  2 , the conductive layer  4  may or may not be provided on the back surface  2   b  of the substrate  2  and on the inner surface of each through-hole  2   c.    
     Also, the substrate  2  may have conductivity in each of the sample support  1 A and the sample support  1 B. According to such a configuration, since a voltage can be applied to the substrate  2  when the ionization method and the mass spectrometry method are performed, the conductive layer  4  can be omitted in each of the sample support  1 A and the sample support  1 B. 
     Also, the support part  30  may define one measurement region R in each of the sample support  1 A and the sample support  1 B. Also, as illustrated in  FIGS. 9 and 10 , the sample support  1 A may further include a reinforcing layer  5  in which a plurality of openings  5   c  are formed to have an aperture ratio larger than the aperture ratio of the through-holes  2   c  in the measurement region R. The reinforcing layer  5  may be formed, for example, in a mesh shape and is provided on the back surface  2   b  side of the substrate  2 . In such a configuration, for example, when the reinforcing layer  5  is brought into contact with a sample such as, for example, a biological sample, components of the sample can be transferred to the first front surface  20   a  of the film part  20  through the openings  5   c  of the reinforcing layer  5  and the through-holes  2   c  of the substrate  2  (that is, the through-holes  20   c  of the film part  20 ). Therefore, according to such a configuration, components of the sample can be transferred to the first front surface  20   a  of the film part  20  while maintaining a two-dimensional distribution of the components of the sample, and a two-dimensional distribution image of the components of the sample can be acquired. Similarly, the sample support  1 B may further include a reinforcing layer in which a plurality of openings are formed to have an aperture ratio larger than the aperture ratio of the through-holes  2   c  in the measurement region R. 
     Also, applications of the sample support  1 A and the sample support  1 B are not limited to the ionization of the sample S using irradiation of the laser beam L. The sample support  1 A and the sample support  1 B can be used for ionization of the sample S using irradiation of an energy beam such as a laser beam, an ion beam, or an electron beam. In the above-described ionization method and mass spectrometry method, the sample S can be ionized by irradiation of an energy beam. 
     REFERENCE SIGNS LIST 
       1 A,  1 B: Sample support,  2 : Substrate,  4 : Conductive layer,  10 : Adapter,  11 : Holding part,  11   a : Reference surface,  16 : Mount part,  20 : Film part,  20   a : First front surface,  20   b : First back surface,  20   c : Through-hole,  30 : Support part,  31 : Inner portion,  31   a : Second front surface,  31   b : Second back surface,  31   c : Outer edge,  32 : Outer portion,  32   a : Third front surface,  32   b : Third back surface,  100 : Mass spectrometer, D: Direction (thickness direction), L: Laser beam (energy beam), P: Focal point, R: Measurement region, S: Sample, S 1 : Component, S 2 : Sample ion (ionized component).