JP2010066060A - Laser eliminating ionizing mass analyzing method and substrate for mass analysis used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the scattering of a fine structure in a laser eliminating ionizing mass analyzing method using a substrate having the fine structure. <P>SOLUTION: In the laser eliminating ionizing mass analyzing method for eliminating the substance to be analyzed, which is supplied to the surface of a substrate for mass analysis, from the substrate for mass analysis by the irradiation with a laser beam and measuring the mass spectrum of the ionized substance to be analyzed, analysis is performed using the substrate 10 for mass analysis having the fine structure 12 and a scattering preventing film 13 formed so as to cover the fine structure 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser desorption / ionization mass spectrometry method for measuring a mass spectrum of a substance to be analyzed by laser light irradiation.

  In mass spectrometry used for identification of substances, a sample supplied on a substrate for mass spectrometry is irradiated with laser light to desorb the analyte from the substrate, and the desorbed analyte is analyzed by mass (more In detail, m / z, where m is a dimensionless quantity obtained by dividing the mass of an ion by a unit of atomic mass, and z is the valence of the charge.) Yes. In such mass spectrometry, the analyte is usually ionized and desorbed. For example, in Time of Flight Mass Spectroscopy (TOF-MS), an analyte that has been ionized and desorbed from a substrate is accelerated by an electromagnetic field generator, and it is made to fly a predetermined distance, and its flight time. Is used to analyze the mass of the analyte.

  However, particularly when a low-volatile substance such as a biological substance or a high-molecular weight substance such as a synthetic polymer is an analyte, it is difficult to desorb the analyte. Therefore, various methods for enabling mass spectrometry of these substances have been studied. Examples of mass spectrometry of high-molecular weight substances such as hardly volatile substances and synthetic polymers include field desorption mass spectrometry (FD-MS), fast atom bombardment mass spectrometry (FAB-MS), and matrix support. Examples include laser desorption ionization (MALDI). Among them, the MALDI method is known as an analytical method that can measure an analyte having a molecular weight exceeding 10,000 and has little chemical influence on a sample.

  In the MALDI method, an analyte is mixed with sinapinic acid or glycerin called a matrix agent as a sample, and the analyte is vaporized together with the matrix agent using the light energy absorbed by the matrix agent. This is a method of ionizing the. MALDI-TOF MS, in which this MALDI method is applied to TOF-MS, has become widespread in the field of biological materials and synthetic polymers, and MALDI-TOF MS that enables more accurate analysis has been studied (patents). Reference 1).

  In these mass spectrometry methods, a high-power laser beam is required to ionize the analyte to be supplied to the surface of the substrate and desorb it from the surface. However, when a high-power laser beam is used, there is a problem that a substance to be analyzed may be damaged and a high-output light source is required, resulting in an increase in cost of the apparatus configuration.

Therefore, in order to keep the power of the laser beam irradiated to desorb the analyte from the substrate low, the laser beam and the microstructure are formed by forming a microstructure having a plurality of nanoparticles on the substrate. A mass spectrometric method and apparatus for efficiently performing ionization using an interaction with a body has been proposed. For example, Non-Patent Document 1 includes a fine structure made of gold fine particles on a substrate and raises the efficiency of ionization by generating localized plasmons on the surface of the substrate.
JP 9-320515 A Lee C. Chen, et al., Journal of Physical Chemistry C, Vol. 111, No. 6, p.2409-2415 (2007)

  However, simply forming a fine structure having nanoparticles causes a problem that nanoparticles are scattered together with the analyte ionized by laser irradiation. Actually, Non-Patent Document 1 shows that an interference peak derived from gold appears in the low molecular weight region of the mass spectrum distribution. Such an interfering peak is a big problem because it lowers the quantitativeness of the analysis. In addition, the scattering of the nanoparticles also causes the inside of the apparatus to be contaminated.

  The present invention has been made in view of the above problems, and efficiently ionizes using the interaction between a laser beam and a fine structure while preventing scattering of a plurality of nanoparticles constituting the fine structure. It is an object of the present invention to provide a laser desorption / ionization mass spectrometry method and a mass spectrometry substrate used therefor.

In order to solve the above problems, a laser desorption ionization mass spectrometry method according to the present invention provides:
In the laser desorption ionization mass spectrometry method of desorbing the analyte supplied on the mass spectrometry substrate from the mass spectrometry substrate by laser light irradiation and measuring the mass spectrum of the ionized analyte,
As a substrate for mass spectrometry, a substrate including a support substrate, a fine structure having a plurality of nanoparticles arranged on the support base, and a scattering prevention film formed so as to cover the fine structure is used. It is characterized by.

  Here, the “nanoparticle” means a nanometer order fine particle. The shape is not particularly limited, and examples thereof include a spherical shape, a rod-like needle shape, and a tube shape. Moreover, the material is not particularly limited, and examples thereof include metals, metal oxides, carbon nanotubes, fullerenes and the like.

  The formation of the anti-scattering film “so as to cover the fine structure” means that the film is formed so as to cover the upper part of the nanoparticles.

  Furthermore, in the laser desorption ionization mass spectrometry method according to the present invention, the scattering prevention film is preferably composed mainly of a translucent material, and the scattering prevention film is composed mainly of SiO2. More preferably. Here, the “main component” means a component having a content of 90% by mass or more.

Moreover, it is preferable that the film thickness of a scattering prevention film satisfies following formula (1).
φ / 2 ≦ d ≦ φ (1)
(Here, d is the film thickness of the anti-scattering film, and φ is the particle size of the nanoparticles.)
The nanoparticles are preferably non-aggregated metal fine particles.

  Here, the “non-aggregated metal fine particles” are (1) those in which the metal fine particles are not associated with each other and the metal fine particles are separated from each other, or (2) the fine particles are integrated after the metal fine particles are combined. In addition, it means metal fine particles contained in any of those that do not return to the original state again.

Furthermore, the substrate for mass spectrometry according to the present invention is:
A substrate for mass spectrometry used in the laser desorption ionization mass spectrometry method described above,
A support substrate;
A microstructure having a plurality of nanoparticles disposed on a support substrate;
And a scattering prevention film formed so as to cover the fine structure.

  In the laser desorption ionization mass spectrometry method and the substrate for mass spectrometry according to the present invention, the nanoparticles constituting the fine structure are covered with the anti-scattering film, so that the nanoparticles can be prevented from scattering. As a result, the interference peak can be reduced and contamination in the apparatus can be prevented.

  Hereinafter, although an embodiment of the present invention is described using a drawing, the present invention is not limited to this.

"Substrate for mass spectrometry"
<First Embodiment>
A first embodiment of a substrate for mass spectrometry according to the present invention will be described. FIG. 1 is a schematic view showing the configuration of the substrate for mass spectrometry according to the present embodiment.

  As shown in FIG. 1, a mass spectrometry substrate 10 according to the present embodiment includes a support substrate 11, a fine structure 12 in which metal fine particles M are arranged on the support substrate 11 as a plurality of nanoparticles, A scattering prevention film 13 formed so as to cover the structure 12 is provided.

  The support substrate 11 is not particularly limited, but is preferably made of a metal material. For example, a stainless plate or the like can be used.

  The microstructure 12 in the present embodiment is obtained by arranging the metal fine particles M as a plurality of nanoparticles on the support substrate 11 approximately regularly. The material of the metal fine particles M is not particularly limited, but can effectively induce localized plasmons and has excellent chemical stability (stability with respect to the sample). Cu, Pt, Ni, Ti and the like are preferable. The pitch of the metal fine particles M is not particularly limited as long as the condition smaller than the wavelength of the laser beam is satisfied. For example, when visible light is used as the laser beam, 200 nm or less is preferable. The particle diameter of the metal fine particles M is not particularly limited and is preferably smaller. The particle diameter of the metal fine particles M is preferably not more than a half wavelength of the irradiation light. Here, the particle diameter of the nanoparticles means the maximum diameter of the nanoparticles. However, for materials having a large aspect ratio such as nanorods and carbon nanotubes described later, the maximum diameter in the direction perpendicular to the major axis direction is meant.

  Further, since the metal fine particles M are non-aggregated metal fine particles, (1) the metal fine particles are not associated with each other and the metal fine particles are separated from each other, or (2) the metal fine particles are integrated after the metal fine particles are bonded. It is a metal fine particle contained in any of those that become particles and do not return to their original state.

  Examples of the fine structure in which a plurality of metal fine particles (1) are arranged include fine structures that are arranged apart from each other by a certain distance so that the metal fine particles do not associate with each other. In this fine structure, the arrangement of the metal fine particles may be random or substantially regular. Examples of the fine structure in which metal fine particles are randomly arranged include a fine structure having an island pattern obtained by an oblique deposition method or the like. Examples of the fine structure in which the metal fine particles are substantially regularly arranged include a dot shape, a mesh shape, a bowtie shape array, and a needle-like metal fine particle patterned so as to be substantially regularly arranged. Patterning in these cases can be performed by a method using processing such as lithography or a focused ion beam method (FIB method) and self-organization.

  The fine structure in which a plurality of metal fine particles of (2) are arranged includes metal fine particles that are integrally formed in the process of metal growth by fusion or plating, and cannot return to the state before being integrated again. A plurality of fine structures can be given.

  In addition to the above, the fine structure 12 can also be formed by applying a dispersion of the metal fine particles M on the surface of the support substrate 11 by a spin coat method or the like and drying. It is preferable that a binder such as resin or protein is contained in the dispersion solution, and the metal fine particles M are arranged on the surface of the support substrate 11 through the binder. When a protein is used as the binder, the metal fine particles M can be arranged on the surface of the support substrate 11 by utilizing a binding reaction between the proteins.

The scattering prevention film 13 is formed so as to cover the fine structure 12. The material of the anti-scattering film 13 is not particularly limited, but is preferably a translucent material, and more preferably SiO2. And it is preferable that the film thickness of a scattering prevention film satisfies following formula (1).
φ / 2 ≦ d ≦ φ (1)
Here, d is the film thickness of the anti-scattering film, and φ is the particle size of the nanoparticles. The lower limit of the film thickness of the anti-scattering film is φ / 2 because the anti-scattering effect cannot be obtained without a certain thickness. However, it is not always necessary to have such a film thickness that the nanoparticles are completely buried. If the film thickness is about half of the particle diameter of the nanoparticles, a sufficient scattering prevention effect can be obtained. On the other hand, the upper limit of the film thickness of the anti-scattering film is φ because the effect of the interaction between the laser beam and the fine structure cannot be obtained if it is too thick. For example, when the nanoparticles are metal fine particles, the effect of the interaction between the laser beam and the fine structure is an electric field enhancement effect by localized plasmons. The range in which this electric field enhancing effect extends is from the metal fine particles to the size of the metal fine particles.

  The substrate 10 for mass spectrometry is a method for irradiating a sample supplied to the substrate surface with laser light, desorbing the analyte contained in the sample from the substrate surface, and mass-analyzing the desorbed analyte. It is used. The substrate 10 for mass spectrometry uses the fact that the energy of the laser beam is increased on the sample supply surface (substrate surface) due to the effect of the interaction between the laser beam and the fine structure generated by the irradiation of the laser beam. The analyte can be desorbed from the sample supply surface by the increased light energy. That is, since the energy of the laser beam can be increased by the above-described interaction on the sample supply surface, the energy of the laser beam itself can be reduced, and as a result, the apparatus cost can be reduced. Here, regarding the ionization of the analyte, the analyte may be ionized before the analyte is desorbed from the sample supply surface, or the analyte is desorbed from the sample supply surface. It may be ionized later.

  In this embodiment, since the fine structure is composed of metal fine particles smaller than the wavelength of the laser beam, localized plasmons are induced. Local plasmon resonance is a phenomenon in which a metal free electron resonates with an electric field of light and vibrates to generate an electric field. In particular, in a metal part having a fine concavo-convex structure, the free electrons in the convex part vibrate in resonance with the electric field of light, thereby generating a strong electric field around the convex part, and localized plasmon resonance is effectively caused. .

  Furthermore, since the substrate for mass spectrometry according to the present embodiment covers the nanoparticles constituting the fine structure with the scattering prevention film, the scattering of the nanoparticles can be prevented. As a result, the interference peak can be reduced and contamination in the apparatus can be prevented.

(Design changes)
In this embodiment, although the material which comprises a nanoparticle was demonstrated as a metal material, in the substrate for mass spectrometry which concerns on this invention, it is not restricted to this. That is, the material constituting the nanoparticles is not limited to a metal material, but may be a metal oxide such as titanium oxide or copper oxide, a magnetic material such as FePtCu, a carbon nanotube, or fullerene.

<Second Embodiment>
A second embodiment of the substrate for mass spectrometry according to the present invention will be described. FIG. 2 is a schematic view showing the configuration of the mass spectrometry substrate 20 according to the present embodiment. This embodiment differs from the first embodiment in that the support substrate 21 in the first embodiment is composed of a porous metal oxide body 41 and a metal layer 42.

  That is, as shown in FIG. 2, the mass spectrometry substrate 20 according to the present embodiment includes a support substrate 21 made of a porous metal oxide body and metal fine particles M as a plurality of nanoparticles arranged on the support substrate 11. The formed fine structure 12 and the scattering prevention film 13 formed so as to cover the fine structure 12 are provided. Here, components similar to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted unless particularly necessary.

  With reference to FIG. 3A-FIG. 3C, the board | substrate for mass spectrometry of 2nd Embodiment which concerns on this invention is demonstrated. The mass spectrometry substrate 20 of the present embodiment constitutes an optical resonator.

  3A to 3C are perspective views showing a manufacturing process of the substrate for mass spectrometry. That is, the mass spectrometric substrate 20 according to the present embodiment forms the fine holes 41a by anodizing the metal to be anodized 40, and the fine structure made of fine metal particles on the surface where the fine holes 41a are formed. 12 is formed, and the anti-scattering film 13 is formed thereon. Therefore, in the present embodiment, unlike the first embodiment, the support substrate 21 is composed of a translucent body 41 and a metal layer 42. The microstructure 12 made of the metal fine particles M is the first reflector, and the metal layer 42 is the second reflector. The substrate for mass spectrometry according to the present embodiment is the optical resonator.

  The translucent body 41 is a translucent microporous body having a plurality of microholes 41a extending from the first reflector (microstructure) 12 side to the second reflector (metal layer) 42 side. It is. The plurality of fine holes 41a are opened on the surface on the fine structure 12 side, and the second reflector 42 side is closed. In the translucent body 41, the plurality of micro holes 41a are substantially regularly arranged with a diameter and a pitch smaller than the wavelength of the laser beam. The translucent microporous body constituting the translucent body 41 is made of, for example, a metal oxide body (Al2O3) obtained by anodizing a part of the anodized metal body (Al) 40, and the second reflector. Reference numeral 42 denotes a non-anodized portion (Al) of the anodized metal body 40.

  Anodization can be carried out by using the metal body to be anodized 40 as an anode, immersing it in an electrolyte together with a cathode, and applying a voltage between the anode and the cathode. The shape of the anodized metal body 40 is not limited, and a plate shape or the like is preferable. Further, it may be used in a form with a support such as a layer in which the anodized metal body 40 is formed on a support. Carbon, aluminum, or the like is used as the cathode. The electrolytic solution is not limited, and an acidic electrolytic solution containing one or more acids such as sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, and benzenesulfonic acid is preferably used.

  When the anodized metal body 40 shown in FIG. 3A is anodized, an oxidation reaction proceeds from the surface 40s in a direction substantially perpendicular to the surface 40s, and a metal oxide body (Al2O3) 41 as shown in FIG. 3B is generated. The The metal oxide body 41 produced by anodization has a structure in which a large number of fine columnar bodies having a substantially regular hexagonal shape in plan view are arranged without gaps. A minute hole 41a extending substantially straight perpendicularly to the surface 40s is opened at a substantially central portion of each fine columnar body, and the bottom surface of each fine columnar body has a rounded shape. The structure of the metal oxide body produced by anodization is Hideki Masuda, “Preparation of mesoporous alumina by anodization and application as a functional material”, Material Technology Vol.15, No.10, 1997, p.34, etc. It is described in.

  As an example of suitable anodizing conditions for producing the metal oxide body 41 having an ordered arrangement structure, when oxalic acid is used as the electrolytic solution, the electrolytic solution concentration is 0.5 M, the liquid temperature is 14 to 16 ° C., and the applied voltage is 40 to 40. ± 0.5V or the like can be mentioned. Usually, the pitch between the adjacent fine holes 41a can be controlled in the range of 10 to 500 nm, and the diameter of the fine holes can be controlled in the range of 5 to 400 nm. Japanese Patent Application Laid-Open Nos. 2001-9800 and 2001-138300 disclose methods for finely controlling the formation position and the hole diameter of fine holes. By using these methods, the micropores having an arbitrary pore diameter and depth within the above range can be arranged almost regularly. The fine holes 41a generated under the above conditions have, for example, a diameter of 5 to 200 nm and a pitch of 10 to 400 nm.

  The first reflector (fine structure) 12 made of metal fine particles can be formed by the same method as in the first embodiment. Moreover, although the 1st reflector 12 consists of a reflective metal, since it has multiple particle | grain gap | intervals which are space | gap, it has a light transmittance, and has a transflective property. The diameter and pitch of the metal fine particles M are designed to be smaller than the wavelength of the laser light L, and the first reflector 12 has an uneven structure smaller than the wavelength of the laser light. The first reflector 12 is a semi-transmissive and semi-reflective thin film having an electromagnetic mesh shielding function because the concavo-convex structure is smaller than the wavelength of light. Here, “semi-transmissive / semi-reflective” means a property having both transparency and reflectivity, and both the transmittance and the reflectance are arbitrary in the range of more than 0% and less than 100%.

  The scattering prevention film 13 can be formed by the same method as in the first embodiment.

The operation of the mass spectrometry substrate 20 according to this embodiment will be described below.
When the laser beam is incident on the mass analysis substrate 20, a part is reflected by the surface of the first reflector 12 according to the transmittance or reflectance of the first reflector 12, and a part is the first reflection. The light passes through the body 12 and enters the light transmitting body 41. The light incident on the translucent body 41 is repeatedly reflected between the first reflector 12 and the second reflector 42. That is, the mass spectrometry substrate 20 has a resonance structure in which multiple reflection occurs between the first reflector 12 and the second reflector 42. Therefore, multiple interference due to multiple reflected light occurs in the translucent body 41, resonates at a specific wavelength satisfying the resonance condition, and absorbs light having the resonance wavelength. The electric field on the substrate surface is enhanced in accordance with the absorption characteristics inside the resonance structure, and an electric field enhancing effect can be obtained on the surface of the first reflector 12 that is the sample supply surface. The substrate 20 for mass spectrometry preferably has a substrate structure with optical impedance matching so that the number of multiple reflections (finesse) in the translucent body 41 is maximized. Such a configuration is preferable because the absorption peak becomes sharp and more effective electric field enhancement is obtained.

Moreover, the substrate 20 for mass spectrometry of this embodiment can change a resonance wavelength according to the thickness of the translucent body 41 and the average refractive index in the translucent body 41. The thickness of the translucent body 41, the average refractive index in the translucent body 41, and the resonance wavelength substantially satisfy the following formula (2). Therefore, if the average refractive index in the translucent body 41 is the same. The resonance wavelength can be changed only by changing the thickness of the translucent body 41.
λ≈2nd / (m + 1) (2)
(In the formula, d is the thickness of the translucent body 41, λ is the resonance wavelength, n is the average refractive index in the translucent body 41, and m is an integer.)
In the case where the light transmitting body 41 is formed of a light transmitting fine hole body as in the present embodiment, the “average refractive index in the light transmitting body 41” refers to the refractive index of the light transmitting fine hole body and its micropores. Average refraction averaged with the refractive index of the material inside (air if there is no filling material in the micropores, and filling material / or filling material and air if there is a filling material in the micropores) Means rate.

  In addition, the refractive index is expressed as a complex refractive index when the material has absorption, but the imaginary part is zero in the light transmitting body 41, and even when the light transmitting body 41 has fine holes, the filling in the fine holes is also performed. Since the influence of the substance is small, in the above formula (2), the refractive index is displayed without a complex part. The resonance condition also changes depending on the physical characteristics and the surface state of the first reflector 12 and the second reflector 42. The magnitude of this change depends on the thickness of the translucent body 41 and the average in the translucent body 41. Since it is smaller than the influence of the refractive index, the resonance wavelength can be determined by the above formula with an accuracy of several nm order.

  As described above, also in this embodiment, since the fine structure 12 is covered with the anti-scattering film 13 as in the first embodiment, the same effect as in the first embodiment can be obtained. .

  Furthermore, in the present embodiment, the light that has passed through the first reflector 12 and entered the translucent body 41 is subjected to multiple reflections between the first reflector 12 and the second reflector 42, and multiple reflected light. Multiple interference occurs due to resonance at a specific wavelength that satisfies the resonance condition. The resonance absorbs light having a resonance wavelength, enhances the electric field in the substrate, and obtains an electric field enhancing effect on the sample supply surface. Since the resonance wavelength changes according to the average refractive index and thickness of the transparent body 41, a high electric field enhancement effect (for example, an enhancement effect of 100 times or more) can be obtained at wavelengths according to these factors. Therefore, the mass spectrometry substrate 20 according to the present embodiment can more efficiently ionize the analyte by using the electric field enhancement effect by the resonance structure.

  The absorption peak due to multiple interference and the absorption peak due to the interaction with the fine structure may appear at different wavelengths or may overlap. Even if the wavelengths of the laser beams deviate from the respective peak wavelengths, the mutual electric field enhancement effect can be enhanced. It is also conceivable that the electric field enhancement effect is strengthened by the interaction of these two phenomena or a phenomenon peculiar to the substrate configuration. As described above, in the mass spectrometry substrate 20, the resonance wavelength λ varies depending on the average refractive index and thickness of the translucent body 41, so that the synergistic effect with the electric field enhancement effect by local plasmon resonance can be obtained most. These factors may be changed as follows.

  Further, since the mass spectrometric substrate 20 of the present embodiment is manufactured using anodization, the mass spectrometric substrate 20 in which the fine holes 41a of the translucent body 41 are substantially regularly arranged is easily manufactured. Is possible.

(Design changes)
In the present embodiment, the case where the first reflector 12 is composed of a metal layer in which a plurality of metal fine particles M having substantially the same diameter are arranged and fixed in a matrix is described. However, the metal fine particles M have a distribution in diameter. The arrangement pattern may be arbitrary and may be a random arrangement. However, a higher structural regularity is preferable because the in-plane uniformity of the resonant structure is higher and the characteristics are concentrated.

  In the present embodiment, only Al is cited as the main component of the anodized metal body 40 used for manufacturing the translucent body 41, but any metal oxide that can be anodized and has translucency can be used. Any metal can be used. Other than Al, Ti, Ta, Hf, Zr, Si, In, Zn, etc. can be used. The anodized metal body 40 may include two or more types of metals that can be anodized.

  In the present embodiment, the light transmitting body 41 in which the fine holes 41a are substantially regularly arranged is produced by using anodic oxidation. However, the method for forming the fine holes 41a is not limited to anodic oxidation. The above-described embodiment using anodization is preferable because the entire surface can be collectively processed, can cope with an increase in area, and does not require an expensive apparatus. However, the surface of the translucent body 41 is not limited to using anodization. Also, a method of forming a plurality of recesses regularly arranged by nanoimprint technology, or a microfabrication technique such as drawing a plurality of recesses regularly arranged by an electron drawing technique such as focused ion beam (FIB), electron beam (EB), etc. Can be formed.

  In the present embodiment, the case where there is no filling material in the fine holes 41a has been described, but there may be a filling material in the fine holes 41a. The filling material is not particularly limited as long as it is a metal, and Au, Ag, Cu, Al, Pt, Ni, Ti, and the like are preferable, and Au and Ag are particularly preferable. A method of filling the fine holes 41a with a metal material can be performed, for example, by electroplating. When performing by electroplating, it is necessary to ensure the conductivity of the bottom of the fine hole 41a. As a method for ensuring conductivity, for example, a method of controlling the conditions so that the metal oxide body at the bottom of the fine hole 41a is particularly thin when anodizing is performed, and the bottom is improved by repeating anodization multiple times. A method of thinning the metal oxide body or a method of removing the metal oxide body at the bottom by etching can be considered. Electroplating is performed by treating a metal body having the fine holes 41a in a plating solution. While the metal oxide body is non-conductive, the bottom of the fine hole 41a is ensured to be conductive by the above treatment. For this reason, the plated metal material is preferentially deposited in the fine hole 41a having a strong electric field, and the fine hole 41a is filled with the plated metal material.

"Laser desorption ionization mass spectrometry method"
Next, the laser desorption ionization mass spectrometry method according to the present invention will be described.

  With reference to FIG. 4, one embodiment of a mass spectrometer for carrying out the mass spectrometry method will be described. The mass spectrometer 100 of this embodiment is a time-of-flight mass spectrometer (TOF-MS). FIG. 4 is a schematic diagram showing the configuration of the mass spectrometer 100 of the present embodiment.

  As shown in the figure, a mass spectrometer 100 includes a mass analysis substrate 10 according to the above-described embodiment and a stage 102 having a substrate holding means for holding the mass analysis substrate 10 in a box 101 kept in a vacuum. The sample supplied to the surface of the mass analysis substrate 10 is irradiated with the laser beam L to desorb the analyte S from the surface of the mass analysis substrate 10, and the desorbed analyte Analyzing means 104 for detecting S and analyzing the mass of the substance S to be analyzed, and disposed between the mass analyzing substrate 10 and the analyzing means 104 at a position facing the surface of the mass analyzing substrate 10. The drawing grid 105 and the end plate 106 disposed opposite to the surface of the drawing grid 105 opposite to the surface of the mass analysis substrate 10 are provided.

The stage 102 is a moving stage capable of moving the mass spectrometry substrate 10 placed on the stage 102 in at least one direction (X direction in the figure). The light irradiation means 103 includes a laser light source. In addition, a light guide system such as a mirror for guiding light emitted from the light source may be provided. Examples of the light source include a pulse laser having a wavelength of 355 nm and a pulse width of about 50 ps to 50 ns.

  The analysis means 104 detects a substance S to be analyzed that has been desorbed from the surface of the mass analysis substrate 10 by irradiation with the laser light L and has flown through the central holes of the extraction grid 105 and the end plate 106. 107, an amplifier 108 that amplifies the output of the detection unit 107, and a data processing unit 109 that processes an output signal from the amplifier 108.

  Hereinafter, mass spectrometry using the mass spectrometer 100 configured as described above will be described. Mass spectrometry is performed on the analyte S supplied on the substrate 10 for mass spectrometry. First, a voltage Vs is applied to the mass spectrometry substrate 10, and a laser beam L having a specific wavelength is irradiated from the light irradiation means 103 to the surface of the mass analysis substrate 10 by a predetermined start signal. The irradiation of the laser beam L enhances the electric field on the surface of the mass spectrometry substrate 10, and the analyte S in the sample is ionized and desorbed from the surface by the optical energy of the laser beam L enhanced by the electric field. To be released. The analyte S may be desorbed after being ionized, or may be deionized after being desorbed.

  The desorbed analyte S is extracted and accelerated in the direction of the extraction grid 105 due to the potential difference Vs between the mass spectrometry substrate 10 and the extraction grid 105, and travels almost straight in the direction of the end plate 106 through the central hole. Then, it flies, passes through the hole of the end plate 106, reaches the detection unit 107, and is detected.

  An output signal from the detection unit 107 is amplified to a predetermined level by the amplifier 108 and then input to the data processing unit 109. In the data processing unit 109, a synchronization signal synchronized with the start signal is input, and the flight time of the analyte S can be obtained based on this synchronization signal and the output signal from the amplifier 108. The mass spectrum can be obtained by deriving m / z from the time.

  In this embodiment, the configuration in which everything is provided in the box 101 has been described. However, at least the mass analysis substrate 10, the drawer grid 105, the end plate 106, and the detection unit 107 are arranged in the box 101. Good.

  In the present embodiment, the case where the mass spectrometer 100 is a TOF-MS has been described as an example. However, the apparatus for performing mass analysis of ionized sample ions is not limited to the TOF type, and IT (Ion Trap; Ion trap type), FT (ICR) (Fourier-Transform Ion Cyclotron Resonance; Fourier transform type), QqTOF (Quadrupole-TOF; Quadrupole-TOF type), TOF- A mass spectrometer such as TOF (TOF connection type) can be used.

  Note that the substrates for mass spectrometry of the first and second embodiments can effectively enhance the electric field on the substrate surface when irradiated with laser light. Therefore, the substrate for mass spectrometry can also be applied as a sensor substrate using the electric field enhancement effect on the substrate surface. For example, a surface-enhanced Raman active substrate (SERS active substrate) is a Raman spectroscopic substrate that can improve the sensitivity of sensing by increasing the intensity of weak Raman scattered light by the electric field enhancement effect on the sample contact surface. The substrate for mass spectrometry can be suitably applied as a SERS active substrate. Therefore, for example, before performing mass spectrometry, mass spectrometry may be performed after sensing by Raman spectroscopy to detect the presence and position of an analyte in mass spectrometry.

<Example>
Examples carried out using the substrate 10 for mass spectrometry according to the present invention and the laser desorption / ionization mass spectrometry method using the same are shown below. The analysis conditions are as follows: analyzer: MALDI-TOFMS AXIMA manufactured by Shimadzu Corporation, excitation wavelength: 355 nm, measurement mode: positive mode and linear mode, sample: Angiotensin I manufactured by SIGMA-ALDRICH, sample concentration: 0.5 mM, solution dropping amount: 0 0.5 ul, fine structure: arrayed metal fine particles, anti-scattering film: SiO 2 (deposition film). FIG. 5 shows an analysis result when there is no scattering prevention film, and FIG. 6 shows an analysis result when there is a scattering prevention film. 5 and 6, it can be seen that the presence of the anti-scattering film can reduce the interference peak derived from gold.

Schematic diagram showing a first embodiment of a substrate for mass spectrometry according to the present invention. Schematic showing a second embodiment of a substrate for mass spectrometry according to the present invention. The perspective view which shows the manufacturing process of the board | substrate for mass spectrometry of 2nd Embodiment which concerns on this invention (the 1) The perspective view which shows the manufacturing process of the board | substrate for mass spectrometry of 2nd Embodiment which concerns on this invention (the 2) The perspective view which shows the manufacturing process of the board | substrate for mass spectrometry of 2nd Embodiment which concerns on this invention (the 3) Schematic which shows the structure of one Embodiment of the mass spectrometer used for the laser desorption ionization mass spectrometry method concerning this invention. Data showing the results of the conventional laser desorption / ionization mass spectrometry method (no scattering prevention film) Data showing the results of the laser desorption / ionization mass spectrometry method according to the present invention (with anti-scattering film)

Explanation of symbols

10, 20 Mass spectrometry substrate 11, 21 Support substrate 12 Fine structure (first reflector)
13 Anti-scattering film 40 Anodized metal body 41 Metal oxide body (translucent body)
41a Fine hole 42 Metal layer (second reflector)
DESCRIPTION OF SYMBOLS 100 Mass spectrometer 101 Box 102 Stage 103 Light irradiation means 104 Analysis means 105 Grid 106 End plate 107 Detection part 108 Amplifier 109 Data processing part L Laser beam M Metal fine particle S Analyte

Claims (6)

In the laser desorption ionization mass spectrometry method for desorbing the analyte supplied on the mass spectrometry substrate from the mass spectrometry substrate by laser light irradiation and measuring the mass spectrum of the ionized analyte.
As the substrate for mass spectrometry, a support substrate, a fine structure having a plurality of nanoparticles arranged on the support base, and a scattering prevention film formed so as to cover the fine structure are provided. A method of laser desorption / ionization mass spectrometry, characterized in that   The laser desorption / ionization mass spectrometry method according to claim 1, wherein the scattering prevention film includes a light-transmitting material as a main component.   3. The laser desorption ionization mass spectrometry method according to claim 2, wherein the scattering prevention film is composed mainly of SiO2. The laser desorption ionization mass spectrometry method according to any one of claims 1 to 3, wherein a film thickness of the scattering prevention film satisfies the following formula (1).
φ / 2 ≦ d ≦ φ (1)
(Here, d is the film thickness of the anti-scattering film, and φ is the particle size of the nanoparticles.)   The laser desorption / ionization mass spectrometry method according to claim 1, wherein the nanoparticles are non-aggregated metal fine particles. A substrate for mass spectrometry used in the laser desorption / ionization mass spectrometry method according to any one of claims 1 to 5,
A support substrate;
A microstructure having a plurality of nanoparticles disposed on the support substrate;
A substrate for mass spectrometry, comprising: a scattering prevention film formed so as to cover the fine structure.

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