Ion analyzer

Abstract

To improve the transport efficiency of ions in a reaction chamber in an ion analyzer that supply precursor ions derived from sample components and active particles such as radicals to the reaction chamber and react the ions with the particles to generate product ions for analysis.SOLUTION: An ion analyzer includes a reaction chamber (132) into which precursor ions derived from sample components are introduced, a multipole ion guide (133) consisting of a plurality of electrodes arranged to surround an ion optical axis (C) which is the central axis of the flight path of the ions in the reaction chamber, an active particle generation unit (4) which generates active particles from a raw material gas, and a radical transport unit (8) having a branching unit which branches the flow of active particles generated in the active particle generation unit into a plurality of different directions and introduces it into the reaction chamber, or a rectifying unit (811) which directs the central axis of the flow of active particles generated in the active particle generation unit out of the space surrounded by the multipole ion guide and introduces it into the reaction chamber.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an ion analyzer that generates and measures product ions by reacting precursor ions derived from sample components with active particles such as radicals. [Background technology]

[0002] MS / MS analysis using a mass spectrometer is performed to identify components contained in a sample and to estimate the molecular structure of unknown components. In MS / MS analysis, ions derived from the sample components (precursor ions) are introduced into a reaction chamber, where the precursor ions are dissociated to generate product ions, which are then mass-separated and detected. Based on the partial structure information obtained from the mass-to-charge ratio of the detected product ions, the sample components can be identified and their molecular structures estimated.

[0003] One method of dissociating precursor ions is to react them with radical species such as oxygen radicals and hydroxyl radicals (e.g., Patent Documents 1 to 4). For example, when precursor ions derived from a peptide are dissociated by reacting them with radicals, product ions that reflect the structure of the peptide, such as the amino acid sequence, are generated. By analyzing the mass spectrum in which such product ions are observed, the structure of the peptide can be deduced.

[0004] Non-Patent Documents 1 and 2 describe radical generators used in carrying out the above-mentioned dissociation method. These radical generators include a straight tube made of a dielectric material and a helical antenna wound around the outer periphery of the straight tube. By supplying high-frequency power to the helical antenna while circulating a source gas (e.g., water vapor) inside the straight tube, plasma of the source gas is generated to generate radicals.

[0005] Patent Document 4 describes a mass spectrometer in which one end of the straight tube is connected to a reaction chamber to supply radicals to the reaction chamber. A multipole ion guide consisting of a plurality of electrodes surrounding the ion optical axis, which is the central axis of the flight path of the ions, is arranged in the reaction chamber, and the straight tube is arranged so that its central axis is perpendicular to the ion optical axis. In the reaction chamber, precursor ions flying along the ion optical axis react with radicals supplied from the end of the straight tube to generate product ions. The precursor ions introduced into the reaction chamber and product ions generated from the precursor ions are transported to the subsequent stage while being converged by the high-frequency electric field formed by the multipole ion guide. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-191081 A [Patent Document 2] International Publication No. 2019 / 155725 [Patent Document 3] International Publication No. 2021 / 095105 [Patent Document 4] International Publication No. 2022 / 059247 [Non-patent literature]

[0007] [Non-Patent Document 1] Yuji Simabukuro, et al., "Tandem Mass Spectrometry of Peptide Ions by Microwave Excited Hydrogen and Water Plasmas", Analytical Chemistry, 2018, Vol.90, No.12, pp.7239-7245 [Non-Patent Document 2] Yuji Simabukuro, "Comprehensive Study on the Low-energy Atomic Hydrogen Beam: From Production to Velocity Distribution Measurement" (Doctoral thesis), [online], [Retrieved June 15, 2023], Doshisha University Academic Repository, Internet <url: https: doshisha.repo.nii.ac.jp ?action="pages_view_main&active_action=repository_view_main_item_detail&item_id=1608&item_no=1&page_id=13&block_id=100"> [Non-licensed document 3] Harmeet Singh, et al., "Recombination coefficients of O and N radicals on stainless steel", Journal of Applied Physics, 2000, vol. 88, No. 6, pp.3748-3755

Non-licensed Document 4

Non-licensed Document 5

Non-licensed Document 6

Non-licensed Document 7

[0008] In a conventional mass spectrometer, a large amount of radicals are supplied locally to a position on the extension line of the central axis of the straight tube of the ion optical axis. At this time, if the radicals supplied to the reaction chamber are oxygen radicals or hydroxyl radicals, the radicals adhere to the electrodes of the multipole ion guide located near the above position, and the electrode surface is locally oxidized and charged up. As a result, there is a problem that an imbalance occurs in the electric field formed by the multipole ion guide, the flight path of the ions flying in the reaction chamber is disturbed, the ion transport efficiency is deteriorated, and the measurement sensitivity is reduced. Here, oxygen radicals and hydroxyl radicals are used as examples, but the electrode surface is also contaminated by other radicals such as nitrogen radicals, causing the same problem as above. In addition, the same problem occurs when precursor ions are dissociated using other active particles such as ozone and metastable particles.

[0009] The problem that the present invention aims to solve is to improve the transport efficiency of ions in a reaction chamber in an ion analyzer that supplies precursor ions derived from sample components and active particles such as radicals to a reaction chamber and reacts the two to generate product ions for analysis. [Means for solving the problem]

[0010] In order to solve the above problems, one aspect of the ion analyzer according to the present invention is to a reaction chamber into which precursor ions derived from a sample component are introduced; a multipole ion guide including a plurality of electrodes arranged to surround an ion optical axis, which is the central axis of the flight path of the ions in the reaction chamber; an active particle generating unit for generating active particles from a raw material gas; an active particle transport unit having a branching unit that branches the flow of active particles generated in the active particle generation unit into a plurality of flows and introduces the flows into the reaction chamber; Equipped with.

[0011] Another aspect of the ion analyzer according to the present invention, which has been made to solve the above problems, is a reaction chamber into which precursor ions derived from a sample component are introduced; a multipole ion guide including a plurality of electrodes arranged to surround an ion optical axis, which is the central axis of the flight path of the ions in the reaction chamber; an active particle generating unit for generating active particles from a raw material gas; an active particle transport unit having a rectifying unit that directs a central axis of the flow of active particles generated in the active particle generation unit to the outside of the space surrounded by the multipole ion guide and introduces the active particles into the reaction chamber; Equipped with. Effect of the Invention

[0012] In the ion analyzer according to the first embodiment and the ion analyzer according to the second embodiment of the present invention, precursor ions derived from sample components and active particles generated in an active particle generator are introduced into a reaction chamber having a multipole ion guide composed of a plurality of electrodes arranged to surround an ion optical axis, and reacted with each other. The active particles may include radicals, ozone, metastable particles, etc.

[0013] In the ion analyzer of the first aspect, the active particle transport section branches the flow of active particles generated in the active particle generation section into multiple branches using the branching section and introduces the branches into the reaction chamber. This distributes the positions to which the active particles are supplied in the reaction chamber to multiple positions, preventing local contamination (e.g., oxidation) of one location of the electrodes constituting the multipole ion guide. Even if the surfaces of the electrodes constituting the multipole ion guide are contaminated over multiple locations, as long as the degree of contamination is uniform, the imbalance of the electric field formed by the multipole ion guide is limited. Therefore, the transport efficiency of ions in the reaction chamber is improved.

[0014] In the ion analyzer of the second aspect, the active particle transport unit directs the flow of active particles generated in the active particle generation chamber to the outside of the space surrounded by the multipole ion guide by the rectifier unit and introduces the flow into the reaction chamber. The space surrounded by the multipole ion guide is the flight space of ions, and the closer the position where the surface of the multipole ion guide is locally contaminated (e.g., oxidized) is to this space, the greater the imbalance of the electric field. In the ion analyzer of the second aspect, the central axis of the flow of active particles is directed to the outside of the space surrounded by the multipole ion guide and introduced into the reaction chamber, so that the surface of the multipole ion guide is less likely to be contaminated at a position close to the flight space of ions, and the imbalance of the electric field is suppressed. Therefore, the transport efficiency of ions in the reaction chamber is improved. Note that since the active particles are neutral particles, they flow in the reaction chamber regardless of the electric field formed by the multipole ion guide and are widely supplied to various places in the space surrounded by the multipole ion guide to react with precursor ions. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of an embodiment of a mass spectrometer according to the present invention; [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of a radical generating unit in the present embodiment. [Diagram 3] 3A and 3B are a cross-sectional view and a perspective view showing the configuration of an attachment attached to the tip of the radical generator in this embodiment. [Figure 4] FIG. 4 is a cross-sectional view of the pipe connection member according to the embodiment. [Diagram 5] FIG. 2 is a side view of a cross section of the radical generator attached to the collision cell in this embodiment. [Figure 6] FIG. 2 is a cross-sectional view of the radical generation unit attached to the collision cell in this embodiment, viewed from above. [Figure 7] FIG. 2 is a cross-sectional view of the radical generator attached to the collision cell in the embodiment, viewed from the direction along the ion optical axis. [Figure 8] FIG. 2 is a diagram for explaining the inscribed circle and the circumscribed circle of a plate electrode that constitutes a multipole ion guide. [Figure 9] The result of reducing a multipole ion guide with hydrogen radicals in a conventional mass spectrometer. [Figure 10] 1 shows the result of reducing a multipole ion guide with hydrogen radicals in the mass spectrometer of this embodiment. [Figure 11] A portion of a product ion spectrum acquired using a conventional mass spectrometer. [Figure 12] 4 is a portion of a product ion spectrum acquired by the mass spectrometer of the present embodiment. [Figure 13] FIG. 4 is a schematic diagram of modified examples 1 to 5 of the radical transport part. [Figure 14] An example of a configuration in which a mesh-like partition is placed between the collision cell and the multipole ion guide. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment of a mass spectrometer according to the present invention will be described below with reference to the drawings. In the drawings used in the following description, the scale of each component is appropriately changed from the actual ratio and some components are omitted in order to make the configuration of the main components in the embodiment easier to understand.

[0017] <Schematic configuration of mass spectrometer 1> 1 shows a schematic configuration of a mass spectrometer 1 according to one embodiment of the present invention. The mass spectrometer 1 of this embodiment is a quadrupole time-of-flight (Q-TOF) mass spectrometer equipped with an atmospheric pressure ion source. This mass spectrometer 1 can be used as a liquid chromatograph mass spectrometer by connecting a liquid chromatograph (LC) to the upstream stage.

[0018] The mass spectrometer 1 of this embodiment has an ionization chamber 10 and a vacuum chamber 100. The inside of the ionization chamber 10 is under an approximately atmospheric pressure atmosphere. The inside of the vacuum chamber 100 is divided into a plurality of compartments (four compartments in this embodiment), which are, in order from the side closest to the ionization chamber 10, a first intermediate vacuum chamber 11, a second intermediate vacuum chamber 12, a first analysis chamber 13, and a second analysis chamber 14. Each of these chambers is evacuated to a vacuum by a vacuum pump (rotary pump and / or turbo molecular pump) not shown, and has a multi-stage differential pumping system configuration in which the degree of vacuum increases in sequence from the ionization chamber 10, which is under an approximately atmospheric pressure atmosphere, to the second analysis chamber 14, which is under a high vacuum atmosphere.

[0019] An electrospray ionization (ESI) probe 101 that applies an electric charge to a liquid sample and sprays it is installed in the ionization chamber 10. A liquid sample containing sample components separated in, for example, an LC column (not shown) is introduced into the ESI probe 101.

[0020] The ionization chamber 10 and the first intermediate vacuum chamber 11 are in communication with each other through a thin-diameter desolvation tube 102 heated by a heat source (not shown). In the first intermediate vacuum chamber 11, an ion guide 111 is arranged, which is composed of a plurality of rod electrodes arranged to surround an ion optical axis C, which is the central axis of the ion flight path, and which focuses ions in the vicinity of the ion optical axis C.

[0021] The first intermediate vacuum chamber 11 and the second intermediate vacuum chamber 12 are separated by a skimmer 112 having a small hole at the top. The second intermediate vacuum chamber 12 also includes an ion guide 121 that is composed of a plurality of rod electrodes arranged to surround the ion optical axis C and focuses ions in the vicinity of the ion optical axis C.

[0022] In the first analysis chamber 13, a quadrupole mass filter 131 that separates ions according to their mass-to-charge ratio (m / z), a collision cell 132 equipped with a multipole ion guide 133 therein, and an ion transport electrode 134 for transporting ions that have passed through the collision cell 132 to a subsequent stage are arranged along the ion optical axis C. The quadrupole mass filter 131 is composed of four rod electrodes. The multipole ion guide 133 is composed of eight plate-shaped electrodes 1331 (see FIG. 7). The ion transport electrode 134 is composed of multiple ring-shaped electrodes.

[0023] An opening 1321 for inserting the discharge tube 410 of the radical generation unit 4 is provided on the wall surface of the collision cell 132. The configuration of the radical generation unit 4 will be described later. A cylindrical tube connection member 1322 is provided so that one end surrounds the opening 1321. A collision induced dissociation (CID) gas supply source 61 is also connected to the collision cell 132. A valve 62 for adjusting the flow rate of a CID gas (e.g., an inert gas such as argon gas) supplied from the CID gas supply source 61 to the collision cell 132 is provided in a flow path connecting the CID gas supply source 61 and the collision cell 132.

[0024] In the collision cell 132, a dissociation method can be performed in which precursor ions are dissociated by radicals such as oxygen radicals supplied from the radical generation unit 4, and a collision-induced dissociation (CID) method can be performed in which precursor ions are accelerated by imparting energy to them and then entering the collision cell 132, where they are dissociated by colliding with a CID gas.

[0025] The second analysis chamber 14 is equipped with an ion transport electrode 141 for transporting the ions incident from the first analysis chamber 13, an orthogonal acceleration section 142 having a pair of a push electrode and a pull electrode arranged opposite to each other across the optical axis C of the ions, an acceleration electrode 143 for accelerating the ions sent out to the flight space by the orthogonal acceleration section 142, a reflectron electrode 144 for forming a return trajectory of the ions in the flight space, an ion detector 145, and a flight tube 146 for forming the flight space therein. The ion detector 145 is, for example, an electron multiplier tube or a multichannel plate.

[0026] The mass spectrometer 1 of this embodiment further includes a control / processing unit 7. The control / processing unit 7 includes a storage unit 71. The storage unit 71 stores information on analytical conditions (measurement conditions, analysis methods, etc.) for various compounds. The control / processing unit 7 includes an analysis execution unit 72 as a functional block. The analysis execution unit 72 sets analytical conditions according to instructions from a user, and performs measurement of a sample and analysis of measurement data based on the set analytical conditions. The control / processing unit 7 is configured, for example, by a general-purpose personal computer (PC), and various functions are realized by executing dedicated control / processing software installed on the computer by a processor. The control / processing unit 7 is connected to an input unit 73 configured, for example, by a mouse and a keyboard, and a display unit 74 configured, for example, by a liquid crystal display.

[0027] <Schematic configuration of radical generating unit 4> 2 is a cross-sectional view of a main part, which is a schematic diagram showing the structure of the plasma generating unit 41 in the radical generating unit 4. The configuration of the radical generating unit 4 shown in FIG. 2 is the same as that of the prior application (Patent Application No. 2022-164919) by the present inventors.

[0028] The plasma generating unit 41 generates plasma of the raw material gas supplied from the raw material gas supply source 48, and introduces radicals generated in the plasma into the collision cell 132. For example, water vapor, oxygen gas, nitrogen gas, dry air, and hydrogen gas are used as the raw material gas. The microwave power supply 46 supplies power for generating the plasma to a helical antenna 411 (described later). The amount of raw material gas supplied from the raw material gas supply source 48 is adjusted by a valve 40 provided in a flow path connecting the raw material gas supply source 48 and the discharge tube 410.

[0029] The plasma generating unit 41 includes a discharge tube 410 made of quartz or aluminum oxide, which is an insulator and a dielectric, a helical antenna 411, which is a belt-shaped conductor wound in a spiral shape around the discharge tube 410, an outer conductor 412, which is a conductor coaxial with the discharge tube 410 and has a cylindrical opening with an inner diameter one size larger than the outer diameter of the discharge tube 410, a permanent magnet 413 embedded in the outer conductor 412, a casing 414 that holds the outer conductor 412, and a permanent magnet 415 arranged at the bottom of the casing 414. For the helical antenna 411, for example, a metal such as copper, preferably a material close to pure copper having high conductivity and formability (oxygen-free copper, tough pitch copper, etc.), is used. In addition, it is preferable that the surface is gold-plated to prevent oxidation.

[0030] The casing 414 is provided with a microwave supply connector 416. The casing 414 is also provided with a light source 417 that emits ultraviolet light inside the discharge tube 410 and a photodetector 418 that detects the light emission of the plasma generated inside the discharge tube 410. The light source 417 is turned on / off based on a control signal transmitted from the analysis execution unit 72. In this embodiment, the light source 417 emits deep ultraviolet light with a wavelength of 275 nm or less. When light in this wavelength band is irradiated onto the discharge tube 410 made of quartz or aluminum oxide, electrons are emitted from the wall surface of the discharge tube 410. These electrons induce plasma. For example, a UV-LED can be used as the light source 417. For the photodetector 418, one that is not sensitive to the wavelength band of the light emitted from the light source 417 and is sensitive only to the wavelength band of the light emitted from the plasma inside the discharge tube 410 is used. For example, a photodiode can be used as the photodetector 418. The detection signal of the photodetector 418 is transmitted to the control and processing unit 7 and stored in the memory unit 71. The analysis execution unit 72 judges the presence or absence of plasma generation by, for example, comparing the magnitude of the detection signal of the photodetector 418 with a predetermined threshold value.

[0031] The discharge tube 410 is a raw material introduction tube into which raw material gas is introduced from the raw material gas supply source 48, and the area inside the discharge tube 410 around which the helical antenna 411 is wound and where ultraviolet light is irradiated from the light source 417 corresponds to the radical generation chamber 4101. The area inside the discharge tube 410 downstream of the radical generation chamber 4101 and the inside of an attachment 8 (described later) disposed between the discharge tube 410 and the collision cell 132 correspond to the radical transport section 4102.

[0032] The microwave supply connector 416 is a coaxial connector, and is connected to the microwave power supply 46 via a coaxial cable. The conductive wire of the coaxial connector is connected to one end of the helical antenna 411. The outer conductor 412 is grounded. A part of the helical antenna 411 and the outer conductor 412 are electrically connected via a resonator adjustment mechanism 420, and the helical antenna 411 is grounded at the connection position. The helical antenna 411, the outer conductor 412, the resonator adjustment mechanism 420, etc. form an electron cyclotron resonance (ECR) resonator. The resonator adjustment mechanism 420 is used to adjust the ECR resonator. The configuration of the resonator adjustment mechanism 420 is the same as that described in Patent Document 3, so a detailed description will be omitted. The microwave power supply 46 supplies power to this resonator via the coaxial cable and the microwave supply connector 416.

[0033] In the plasma generating unit 41 of the present embodiment, local inductively coupled discharge and electron cyclotron resonance are used to generate and maintain plasma. In this plasma generating unit 41, the density of the plasma can be increased and stabilized by ECR.

[0034] A substantially disk-shaped magnet holder 51 is attached to the bottom surface of the casing 414. The casing 414 and the magnet holder 51 function as a holding member 50 that holds the discharge tube 410. An opening is formed in the center of the magnet holder 51 through which the discharge tube 410 and the guide member 52 are inserted. The guide member 52 is a cylindrical member that is arranged coaxially with the discharge tube 410 and on the outer periphery of the discharge tube 410, and a compression spring 56 that expands and contracts in the axial direction of the discharge tube 410 is attached to the outer periphery of the guide member 52. A cylindrical protector 53 is provided at the tip of the guide member 52. The guide member 52 and the protector 53 are arranged on the outer periphery of the tip portion of the discharge tube 410 that is exposed from the magnet holder 51, and the tip of the protector 53 is located outward from the tip of the discharge tube 410. As a result, the guide member 52 , the protector 53 and the compression spring 56 function as a tube protection member 54 that protects the outer periphery and the tip of the portion of the discharge tube 410 that is exposed from the holding member 50 .

[0035] <Attachment of the radical generator 4 and the attachment 8 to the collision cell 132> The collision cell 132 is fixed to the vacuum chamber 100 at a portion not shown. Openings are formed in the walls of the vacuum chamber 100 and the collision cell 132, and a tube connecting member 1322 is inserted into both openings. An attachment 8 is attached to the tube connecting member 1322.

[0036] FIG. 3 is a schematic cross-sectional view (left) and an internal perspective view (right) of the attachment 8. The attachment 8 is composed of a ring-shaped base 81 with a closed bottom surface, and a cylindrical part 82 with a smaller outer diameter. The inner diameter of the base 81 is the same as that of the cylindrical part 82. Eight through-holes 811 are formed radially at equal intervals on the periphery of the base 81 in a direction perpendicular to the central axis of the discharge tube 410 (the central axis of the flow of radicals flowing out from the end of the discharge tube 410) in a horizontal plane. The eight through-holes are formed to extend in one direction in a plane parallel to the ion optical axis when attached to the collision cell 132.

[0037] In addition, a tapered portion 821 that expands upward is formed at the upper end of the cylindrical portion 82. The tapered portion 821 functions as a guide when inserting the tip of the discharge tube 410. In this embodiment, eight through holes 811 are provided, but the number of through holes 811 may be at least one. In this embodiment, the central axis of the flow of radicals generated in the radical generation chamber 4101 is directed horizontally. This makes it difficult for the surface of the electrode 1331 of the multipole ion guide 133 to be contaminated at a position close to the flight space of the ions, and suppresses the imbalance of the electric field. Therefore, the transport efficiency of ions in the collision cell 132 is improved. Note that since radicals are neutral particles, they flow inside the collision cell 132 regardless of the electric field formed by the multipole ion guide 133, and are widely supplied to various places in the space surrounded by the multipole ion guide 133 to react with precursor ions.

[0038] As described above, at least one through hole 811 is sufficient, but the more the number of through holes 811 is increased, the more the radical flow can be dispersed and the more uniformly the radicals can be supplied inside the collision cell 132. When two through holes 811 extending in opposite directions are provided, depending on the mounting state of the attachment 8, the two through holes 811 may be arranged parallel to the ion optical axis C, and many radicals may be supplied onto the ion optical axis C. Even in this case, the effect of dispersing the radical flow can be obtained, but in order to prevent many radicals from being directly supplied onto the ion optical axis C, it is preferable that three or more through holes 811 are provided radially.

[0039] Non-Patent Document 3 describes that oxygen recombines (disappears) on the stainless steel surface with a probability of a recombination coefficient γ=0.17. Non-Patent Document 4 describes that oxygen atoms are hardly lost on the surface of an oxide, and also describes that the recombination coefficient γ of quartz is 0.000016. Non-Patent Document 5 describes that the recombination coefficient γ of hydrogen radicals and quartz is γ=0.0026. Non-Patent Document 6 also describes the recombination of hydrogen radicals and quartz, similar to Non-Patent Document 5. From the descriptions in Non-Patent Documents 4 and 5, it can be seen that hydrogen radicals are more likely to disappear than oxygen radicals on the surface of quartz. Non-Patent Document 7 describes that the recombination coefficient γ of hydrogen radicals and oxygen radicals for PTFE is about 0.001 for both.

[0040] From the descriptions in Non-Patent Documents 3 to 7, it can be said that if a metal is present in the radical flow path, the radicals are likely to disappear, and in order to suppress the disappearance of the radicals, it is preferable to form the radical flow path with the insulating material as described above. Therefore, the attachment 8 of this embodiment is made of an insulating material. As the insulating material, for example, a resin material such as polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), polyimide (PI), or a ceramic such as quartz can be used. In this embodiment, in order to prevent the tip of the discharge tube 410 from being damaged when the discharge tube 410 is inserted into the attachment 8, the inner diameter of the attachment 8 is made larger than the outer diameter of the discharge tube 410. However, in order to prevent the radicals from flowing out from between the attachment 8 and the tip of the discharge tube 410, the cross-sectional area (conductance) of the gap between the inner peripheral surface of the attachment 8 and the outer peripheral surface of the discharge tube 410 is made sufficiently smaller than the total cross-sectional area (conductance) of the eight through holes 811 provided in the attachment 8. Specifically, the area of ​​the former should be 1 / 10 or less, more preferably 1 / 20 or less, of the area of ​​the latter.

[0041] First, the attachment 8 is attached to the tube connection member 1322. Then, the tube connection member 1322 to which the attachment 8 is attached is attached to the collision cell 132. When the radical generation unit 4 is attached to the collision cell 132, the radical generation unit 4 is inserted into the tube connection member 1322 from above. As shown in the cross-sectional view of FIG. 4, a step portion 1323 in which the inner diameter becomes smaller is provided inside the tube connection member 1322, and the attachment 8 is screwed from below into the small-diameter space separated by this step portion 1323 (the space below the step portion 1323 in FIG. 4) and fixed. When the tip of the protector 53 reaches the step portion 1323 of the tube connecting member 1322 and the radical generation unit 4 is further inserted, the tip of the protector 53 is pressed against the step portion 1323, the compression spring 56 contracts, and the tip of the discharge tube 410 becomes exposed from the tip of the protector 53 and is inserted into the cylindrical portion 82 of the attachment 8.

[0042] In this embodiment, as in the above-mentioned prior application, the outside of the discharge tube 410 is protected by the protector 53 until the tip of the discharge tube 410 is inserted into the cylindrical portion 82 of the attachment 8, thereby preventing the discharge tube 410 from being damaged when the radical generation unit 4 is attached.

[0043] Figure 5 is a side view of a cross section of the radical generation unit 4 attached to the collision cell 132, Figure 6 is a top view of a cross section (cross section AA in Figure 5) of the radical generation unit 4 attached to the collision cell 132, and Figure 7 is a cross section (cross section BB in Figure 5) of the radical generation unit attached to the collision cell 132 in this embodiment, viewed from the direction along the ion optical axis.

[0044] 5 and 6, the radical generation part 4 is attached to a position near the outlet of the collision cell 132. Also, as shown in Fig. 5 and 6, the radical generation part 4 is attached so that the central axis of the discharge tube 410 intersects with the ion optical axis C (orthogonal in this embodiment).

[0045] In a conventional mass spectrometer, the tip of the discharge tube is exposed to the collision cell without using the attachment 8. As in this embodiment, the discharge tube is arranged so that its central axis intersects (is perpendicular to) the ion optical axis C, and therefore a large amount of radicals are supplied locally to the extension of the central axis of the discharge tube on the ion optical axis C.

[0046] Various radicals are used in the dissociation method in which precursor ions react with radicals. When the radicals supplied to the collision cell are oxygen radicals or hydroxyl radicals, the radicals adhere to the electrodes of the multipole ion guide near the intersection of the central axis of the discharge tube and the ion optical axis C, causing the electrode surface to be locally oxidized and charged up. When the parts of the electrodes that make up the multipole ion guide that face the ion optical axis C are oxidized, the electric field becomes significantly disturbed, and when the parts close to the ion optical axis C are oxidized in particular, the electric field becomes even more disturbed. As a result, an imbalance occurs in the electric field formed by the multipole ion guide, disturbing the flight paths of ions flying in the collision cell, reducing the ion transport efficiency and decreasing the measurement sensitivity.

[0047] In addition, when the collision cell contains radicals with reducing ability, such as hydrogen radicals, the oxide film formed on the surface of the multipole ion guide is locally reduced only in the vicinity of the above-mentioned position. As a result, an imbalance occurs in the electric field formed by the multipole ion guide, as in the above, and the flight path of the ions flying in the collision cell is disturbed, resulting in poor ion transport efficiency and reduced measurement sensitivity.

[0048] Furthermore, substances adhering to the inner wall surface of the discharge tube may be detached by the plasma of the raw material gas and flow into the collision cell together with the radicals. In conventional mass spectrometers, not only radicals but also these substances flow onto the ion optical axis, so ions derived from these substances are transported to the rear together with product ions. As a result, the mass peaks of ions derived from these substances appear as impurity peaks in the product ion spectrum, causing background noise.

[0049] On the other hand, in this embodiment, as shown in Fig. 5 to Fig. 7, the radicals flowing out from the tip of the discharge tube 410 are dispersed and guided to eight through-holes 811 formed in the attachment 8, and are supplied to the collision cell 132 from the outlet of each through-hole 811. Therefore, the surface of the plate electrode 1331 constituting the multipole ion guide 133, particularly the portion facing the ion optical axis C, is not locally oxidized by radicals having an oxidizing ability (for example, oxygen radicals and hydroxyl radicals), and disturbance of the electric field formed by the multipole ion guide 133 is suppressed. In addition, the surface of the plate electrode 1331 constituting the multipole ion guide 133 is not locally reduced by radicals having a reducing ability (for example, hydrogen radicals), and in this respect, disturbance of the electric field formed by the multipole ion guide 133 is also suppressed.

[0050] Furthermore, in this embodiment, the through holes 811 of the attachment 8 are provided parallel to and radially from the ion optical axis C, so that the amount of material flowing into the vicinity of the ion optical axis C together with the radicals is suppressed. The space surrounded by the electrodes constituting the multipole ion guide 133 (the space represented by the inscribed circle 1332 of the eight plate electrodes 1331 in the cross-sectional view shown in FIG. 8) is the flight region of the ions, and the impurity ions that flow into this region are likely to be transported to the rear stage. In this embodiment, the central axis of the flow of radicals supplied from each through hole 811 is directed outward from the space corresponding to the inscribed circle 1332 of the eight plate electrodes 1331 in the cross-sectional view shown in FIG. 8, so that the amount of material that detaches from the wall surface of the discharge tube 410 and flows into the space surrounded by the electrodes constituting the multipole ion guide 133 together with the radicals is reduced. Although not essential to the present invention, in this embodiment, the central axis of each through-hole 811 is parallel to the ion optical axis C, and each through-hole 811 directs the central axis of the radical flow outside the space corresponding to the circumscribing circle 133 located further outside than the inscribing circle 1332. This further suppresses adhesion of radicals to the electrodes of the multipole ion guide 133, and reduces background noise in the product ions caused by ions derived from these substances.

[0051] In order to confirm the effect of adopting the configuration of this embodiment, a multipole ion guide 133 was constructed using a plate electrode 1331 whose surface was uniformly oxidized, and an experiment was conducted to supply hydrogen radicals. As a result, in a conventional mass spectrometer in which hydrogen radicals were supplied directly onto the ion optical axis from the tip of the discharge tube 410 without using the attachment 8, only the portion located on the extension line of the central axis of the discharge tube 410 was locally reduced, as shown in FIG. 9. On the other hand, in the mass spectrometer 1 of this embodiment in which the attachment 8 was used to branch the flow of radicals into multiple parts and uniformly flow radicals into the space in the collision cell 132, the entire plate electrode 1331 was reduced. Note that FIG. 9 and FIG. 10 are photographs of the eight plate electrodes constituting the multipole ion guide removed from the mass spectrometer and arranged side by side.

[0052] In addition, product ion spectra were obtained using a conventional mass spectrometer and the mass spectrometer 1 of this embodiment. Fig. 11 shows the low mass-to-charge ratio portion (mainly the portion where peaks of impurity ions appear) of the product ion spectrum obtained by the conventional mass spectrometer. In Fig. 11, impurity peaks of many ions having low mass-to-charge ratios appear with high intensity. For example, the ion at m / z=18.033 is derived from water molecules, the ion at m / z=29.997 is derived from nitric oxide, and multiple peaks with a mass-to-charge ratio difference of 14 are derived from hydrocarbon molecules with different numbers of CH2, all of which are peaks of impurity ions.

[0053] Figure 12 shows the low mass-to-charge ratio portion (where peaks of impurity ions mainly appear) of the product ion spectrum acquired by the mass spectrometer 1 of this embodiment. Note that the vertical axis intensity in Figure 12 differs by two orders of magnitude from that in Figure 11 (100,000 times in Figure 11, and 1,000 times in Figure 12). It can be seen that the types and intensities of the impurity peaks are both greatly reduced in comparison with Figure 11.

[0054] The above embodiment is merely an example and can be modified as appropriate in accordance with the spirit of the present invention.

[0055] In the above embodiment, the attachment 8 is attached to the tip of the discharge tube 410, and eight through holes 811 are formed radially at equal intervals inside the attachment 8, but the intervals between the through holes 811 do not have to be equal. Also, a configuration different from the above embodiment can be adopted. For example, the tip of the discharge tube 410 may be sealed, and multiple openings may be formed in the circumferential portion of the tip of the discharge tube 410, and radicals may be supplied to the collision cell 132 through the multiple openings.

[0056] All of the above examples are configurations corresponding to both the branching section in the present invention, which branches the radical flow into multiple parts and introduces them into the collision cell 132, and the rectifying section, which directs the central axis of the radical flow outside the space surrounded by the multipole ion guide 133 and introduces it into the collision cell 132. However, it is not essential for the present invention to have both of these, and a configuration corresponding to only one of them may be used.

[0057] 13 shows schematic cross sections of the discharge tube 410 and the attachment 8 for modified examples 1 to 5 of the configuration of the radical transport section having the functions of a branching section and / or a rectifying section. In each modified example, the left side shows a cross section of the side, and the right side shows a cross section perpendicular to the ion optical axis.

[0058] In the first modification, one through hole 811 extending in a direction parallel to the ion optical axis C is formed, and this radical transport section is one of the aspects including the rectifying section. In the second modification, three through holes 811 extending in a direction parallel to the central axis of the discharge tube 410 are formed, and this radical transport section is one of the aspects including the branching section. In the third modification, two through holes 811 are formed rotationally symmetrically with respect to the central axis of the discharge tube 410 and extending in a direction non-parallel to both the central axis and the ion optical axis C, and each through hole 811 directs the central axis of the radical flow outside the space surrounded by the multipole ion guide 133. This radical transport section is one of the aspects including both the branching section and the rectifying section.

[0059] In the fourth modification, one through hole 811 having a central axis coinciding with the central axis of the discharge tube 410 is formed. However, the discharge tube 410 and the through hole 811 are attached at a position deviated from the ion optical axis C, and the central axis of the flow of radicals introduced from the discharge tube 410 and the through hole 811 is directed to the outside of the space surrounded by the multipole ion guide 133. This radical transport unit is one of the aspects having the rectification unit. In the fifth modification, the discharge tube 410 is directly connected to the collision cell 132, and does not have the attachment 8. In the fifth modification, the discharge tube 410 is attached at a position deviated from the ion optical axis C, and the central axis of the flow of radicals introduced from the discharge tube 410 is directed to the outside of the space surrounded by the multipole ion guide 133. This radical transport unit is also one of the aspects having the rectification unit. As in the fourth and fifth modifications, the rectification unit is not limited to one that deflects the flow of radicals.

[0060] In the above examples, the attachment 8 is disposed near the tip of the discharge tube 410 to form the radical transport section, or the radical transport section is formed only by the discharge tube 410. However, a configuration equivalent to the branching section or rectifying section may be disposed at a position away from the tip of the discharge tube 410. For example, as shown in FIG. 14, a mesh-shaped partition 135 may be disposed between the inner wall surface of the collision cell 132 and the multipole ion guide 133, and radicals may be introduced into the space between the inner wall surface of the collision cell 132 and the partition 135, and the radicals may be supplied from a number of openings provided in the partition 135. Note that the partition 135 is preferably made of an insulating material, as with the attachment 8 in the above embodiment. Specifically, for example, a resin material such as a polyimide film having a number of openings formed therein may be suitably used.

[0061] In the above embodiment, the mass spectrometer is equipped with a Q-TOF type mass separator, but any mass separator can be used. In addition, in the above embodiment, the ion source is equipped with an ESI probe 101 that generates ions from a liquid sample, but other atmospheric pressure ion sources such as an APCI probe can be used. Alternatively, an ion source that generates ions in a vacuum atmosphere can be used. Furthermore, an ion source that generates ions from a gas or solid sample can be used. Furthermore, in the above embodiment, a collision cell 132 is used to react precursor ions with radicals, but other reaction chambers such as a three-dimensional ion trap can be used.

[0062] Although the above embodiment is a mass spectrometer, a similar configuration can also be adopted in an ion mobility spectrometer that separates ions according to their mobility.

[0063] In the above embodiment, the light source 417 is used to irradiate the discharge tube 410 made of quartz or aluminum oxide with ultraviolet light. However, the plasma may be generated without using the light source 417 .

[0064] In the above embodiment, the radical generator 4 generates radicals from the raw material gas by inductively coupled plasma, but radicals may be generated from the raw material gas by capacitively coupled plasma. Also, a similar configuration to the above can be used in a mass spectrometer equipped with a radical generator (e.g., Non-Patent Document 8) that generates radicals by introducing a raw material gas into a heated discharge tube.

[0065] In the above embodiment, the precursor ion reacts with the radical, but the precursor ion can be dissociated at a specific position by using active particles other than radicals, such as ozone or metastable particles. The same configuration as the above embodiment can be adopted when using active particles other than radicals. Note that metastable particles refer to atoms (metastable atoms) or molecules (metastable molecules) in a long-life excited state.

[0066] [Aspects] It will be apparent to those skilled in the art that the above-described exemplary embodiments are illustrative of the following aspects.

[0067] (Section 1) An ion analyzer according to one aspect of the present invention comprises: a reaction chamber into which precursor ions derived from a sample component are introduced; a multipole ion guide including a plurality of electrodes arranged to surround an ion optical axis, which is the central axis of the flight path of the ions in the reaction chamber; an active particle generating unit for generating active particles from a raw material gas; an active particle transport unit having a branching unit that branches the flow of active particles generated in the active particle generation unit into a plurality of flows and introduces the flows into the reaction chamber; Equipped with.

[0068] (Section 2) The ion analyzer according to paragraph 2 is the ion analyzer according to paragraph 1, The branching portion branches the stream of active particles in a number of different directions.

[0069] (Section 3) An ion analyzer according to another aspect of the present invention comprises: a reaction chamber into which precursor ions derived from a sample component are introduced; a multipole ion guide including a plurality of electrodes arranged to surround an ion optical axis, which is the central axis of the flight path of the ions in the reaction chamber; an active particle generating unit for generating active particles from a raw material gas; an active particle transport unit having a rectifying unit that directs a central axis of the flow of active particles generated in the active particle generation unit to the outside of the space surrounded by the multipole ion guide and introduces the active particles into the reaction chamber; Equipped with.

[0070] In the ion analyzer according to paragraph 1 and the ion analyzer according to paragraph 3, precursor ions derived from sample components and active particles generated in an active particle generation unit are introduced into a reaction chamber having a multipole ion guide consisting of a plurality of electrodes arranged to surround the ion optical axis, and the two are reacted with each other.

[0071] In the ion analyzer according to the first aspect, the active particle transport unit branches the flow of active particles generated in the active particle generation unit into multiple flows by the branching unit and introduces the flows into the reaction chamber. This distributes the active particles to multiple positions in the reaction chamber. In the ion analyzer according to the second aspect, the analysis unit branches the flow of active particles into multiple different directions, so that the active particles are distributed and supplied over a wider range in the reaction chamber. In the ion analyzer according to the first aspect and the ion analyzer according to the second aspect, one part of the electrodes constituting the multipole ion guide is not locally contaminated (e.g., oxidized). Even if the surfaces of the electrodes constituting the multipole ion guide are contaminated over multiple points, as long as the degree of contamination is uniform, the imbalance of the electric field formed by the multipole ion guide is limited. Therefore, the transport efficiency of ions in the reaction chamber is improved.

[0072] In the ion analyzer according to the third aspect, the active particle transport unit directs the flow of active particles generated in the active particle generation chamber to the outside of the space surrounded by the multipole ion guide by the rectifier unit, and introduces the flow into the reaction chamber. The space surrounded by the multipole ion guide is the flight space of ions, and the closer to this space the position where the surface of the multipole ion guide is locally contaminated (e.g., oxidized), the greater the imbalance of the electric field. In the ion analyzer according to the second aspect, the central axis of the flow of active particles is directed to the outside of the space surrounded by the multipole ion guide, and the surface of the multipole ion guide is less likely to be contaminated at a position close to the flight space of ions, and the imbalance of the electric field is suppressed. Therefore, the transport efficiency of ions in the reaction chamber is improved. Note that since the active particles are neutral particles, they flow in the reaction chamber regardless of the electric field formed by the multipole ion guide, and flow into various places in the space surrounded by the multipole ion guide to react with precursor ions.

[0073] (Section 4) The ion analyzer according to paragraph 4 is an ion analyzer according to any one of paragraphs 1 to 3, the active particle generation unit generates active particles from the raw material gas in an active particle generation chamber formed inside a tube, The active particle transport portion includes an attachment disposed on a distal side of the tube.

[0074] In the ion analyzer according to the fourth aspect, the ion analyzer according to the present invention can be easily constructed by simply attaching an attachment to the tip of the active particle generation unit used in conventional mass analyzers or the like.

[0075] (Section 5) The ion analyzer according to paragraph 5 is an ion analyzer according to paragraph 4, The attachment is made of an insulating material.

[0076] In the ion analyzer according to the fifth aspect, the loss of active particles inside the attachment can be suppressed.

[0077] (Section 6) The ion analyzer according to paragraph 6 is an ion analyzer according to paragraph 4 or 5, The attachment has a plurality of through holes formed radially about the flow of active particles at the outlet of the tube.

[0078] In the ion analyzer according to the sixth aspect, the flow of active particles can be uniformly dispersed among a plurality of through-holes.

[0079] (Section 7) The ion analyzer according to paragraph 7 is an ion analyzer according to any one of paragraphs 4 to 6, The attachment has a plurality of through holes extending in different directions within a plane parallel to an ion optical axis, which is the central axis of the flight path of ions in the reaction chamber, but not including the ion optical axis.

[0080] In the ion analysis device according to the seventh aspect, active particles are supplied from through-holes formed in a direction parallel to the ion optical axis, thereby making it possible to prevent active particles from being supplied locally near the ion optical axis.

[0081] (Section 8) The ion analyzer according to paragraph 8 is an ion analyzer according to any one of paragraphs 4 to 7, The attachment has three or more through holes extending in different directions.

[0082] In the ion analysis device according to paragraph 8, regardless of how the attachment is attached, at least one through-hole extends in a direction non-parallel to the ion optical axis, so that it is possible to prevent active particles from being supplied locally near the ion optical axis. [Explanation of symbols]

[0083] 1...Mass spectrometer 10…Ionization chamber 100…Vacuum chamber 101…ESI probe 11…First intermediate vacuum chamber 12...Second intermediate vacuum chamber 13…1st analysis room 131...Quadrupole mass filter 132…Collision cell 1321…Aperture 1322...Pipe connection parts 1323…Step 133...Multipole ion guide 1331...Plate electrode 1332...Inscribed circle of eight plate electrodes 1333…Circumscribed circle of eight plate electrodes 134...Ion transport electrode 135…Mesh partition 14…Second analysis room 141...Ion transport electrode 142...Orthogonal acceleration section 143...acceleration electrode 144...Reflectron electrode 145…Ion detector 146…Flight tube 4... Radical generation section 40…Valve 41...Plasma generating section 410...discharge tube 4101…Radical generation room 4102... Radical transport unit 411…Helical antenna 412...Outer conductor part 413, 415...Permanent magnets 414…Casing 416...Microwave supply connector 417...Light source 418...Photodetector 420…Resonator adjustment mechanism 46...Microwave power supply 48…Source gas supply source 50...Retaining member 51...Magnet holder 52...Guide member 53…Protector 54...Pipe protection member 61…CID gas supply source 61...Gas supply source 62…Valve 7…Control and processing section 71...Storage section 72…Analysis Execution Department 8…Attachment 81...Base 811...Through hole 82...Cylindrical part 821...Tapered section C…Ion optical axis< / url:>

Claims

1. A reaction chamber into which precursor ions derived from the sample components are introduced, A multipole ion guide consisting of multiple electrodes arranged to surround the ion optical axis, which is the central axis of the ion flight path in the reaction chamber, An active particle generation unit that generates active particles from a raw material gas, The active particle transport unit has a branching section that branches the flow of active particles generated in the active particle generation section into multiple branches and introduces them into the reaction chamber. An ion analyzer equipped with the following features.

2. The ion analyzer according to claim 1, wherein the branching section branches the flow of the active particles in a plurality of different directions.

3. A reaction chamber into which precursor ions derived from the sample components are introduced, A multipole ion guide consisting of multiple electrodes arranged to surround the ion optical axis, which is the central axis of the ion flight path in the reaction chamber, An active particle generation unit that generates active particles from a raw material gas, The active particle transport unit has a flow straightening section that directs the central axis of the flow of active particles generated in the active particle generation section out of the space surrounded by the multipole ion guide and introduces them into the reaction chamber. An ion analyzer equipped with the following features.

4. The active particle generation unit generates active particles from the raw material gas in an active particle generation chamber formed inside the tube. The ion analyzer according to claim 1 or 3, wherein the active particle transport unit comprises an attachment positioned at the tip of the tube.

5. The ion analyzer according to claim 4, wherein the attachment is made of an insulating material.

6. The ion analyzer according to claim 4, wherein the attachment has a plurality of through-holes formed radially around the flow of active particles at the outlet of the tube.

7. The ion analyzer according to claim 4, wherein the attachment has a plurality of through holes formed in a plane parallel to the ion optical axis, which is the central axis of the ion flight path in the reaction chamber, and extending in different directions in a plane that does not include the ion optical axis.

8. The ion analyzer according to claim 4, wherein the attachment has three or more through holes that extend in different directions from each other.

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