Ion analysis device

Abstract

An ion analysis device (1) comprises: a reaction chamber (132) at which an insulating material (1323) is formed at at least a portion of an inner circumferential surface and into which precursor ions derived from a sample component are introduced; and an active particle introduction unit (4) that generates active particles from a starting material gas and introduces the active particles into the reaction chamber. One embodiment also comprises a multipolar ion guide (1333) that comprises a plurality of electrodes (1331) that are arranged so as to surround an ion optical axis (C) that is the center axis of the flight path of ions through the reaction chamber. The plurality of electrodes are formed by cutting off a portion (1334) of a plate-shaped or columnar substrate that does not include the portion that is to face the ion optical axis and thereby reducing the surface area to less than the substrate.

Description

Ion analyzer

[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.

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

[0003] One method for dissociating precursor ions involves reacting them with radical species such as hydrogen radicals, oxygen radicals, hydroxyl radicals, and nitrogen radicals (see, for example, Patent Documents 1 to 4). For example, when precursor ions derived from peptides are dissociated by reacting them with radicals, product ions that reflect the structure of the peptide, such as its amino acid sequence, are generated. By analyzing the mass spectrum in which these 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 dielectric tube and a helical antenna wound around the outer periphery of the tube, and generate plasma of the source gas by supplying high-frequency power to the helical antenna while circulating a source gas (e.g., water vapor) inside the tube, thereby generating radicals. Patent Document 4 describes a mass spectrometer in which one end of the tube is connected to a reaction chamber to supply radicals to the reaction chamber.

[0005] Japanese Patent Application Laid-Open No. 2019-191081 International Publication No. 2019 / 155725 International Publication No. 2021 / 095105 International Publication No. 2022 / 059247 Japanese Patent Application Laid-Open No. 2007-128694

[0006] 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. 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>. Harmeet Singh, et al., "Recombination Coefficients of O and 88, No. 6, pp.3748-3755J. C. Greaves et al., "RECOMBINATION OF ATOMS AT SURFACES, PART 5.-OXYGEN ATOMS AT OXIDE SURFACES", Trans. Faraday Soc., 1959, 55, pp.1346-1354Rok Zaplotnik, et al., "Atomic oxygen and hydrogen loss coefficient on functionalized polyethylene terephthalate, polystyrene, and polytetrafluoroethylene polymers", May 2018, Plasma Processes and Polymers 15(9):e1800021, DOI:10.1002 / ppap.201800021, [online], [Retrieved June 29, 2023], <URL: https: / / onlinelibrary.wiley.com / doi / abs / 10.1002 / ppap.201800021> "Thermal spraying", Process Co., Ltd., [online], [Retrieved August 10, 2023], <URL: http: / / www.process-1.co.jp / product / index-use04.php> "Teflon coating types and characteristics", Yumoto Electric Co., Ltd., [online], [Retrieved August 10, 2023], <URL: https: / / www.yumoto.jp / technology / onepoint / teflon-coating>"Here's the key! What is the substrate design suitable for TeflonTM fluororesin coating?", Coating Magazine, Yoshida SKT Co., Ltd., [online], [Retrieved August 10, 2023], <URL: https: / / www.y-skt.co.jp / magazine / coating / base_engineering / >"PBI, PI coating: high-performance plastic coating", Yoshida SKT Co., Ltd., [online], [Retrieved August 10, 2023], <URL: https: / / www.y-skt.co.jp / products-pbi-pi.html> Hidenori Takahashi and six others, "Hydrogen Attachment / Abstraction Dissociation (HAD) of Gas-Phase Peptide Ions for Tandem Mass Spectrometry," Analytical Chemistry, 2016, Vol. 88, No. 7, pp. 3810-3816.

[0007] In conventional mass spectrometers, the reaction chamber is provided inside a cylindrical body made of metal. As described in Non-Patent Document 3, for example, the recombination coefficient between radicals and metals is high, and when radicals introduced into the reaction chamber come into contact with the inner circumferential surface of the reaction chamber, they tend to recombine with the metal atoms that make up the inner circumferential surface and disappear. This has led to the problem of difficulty in increasing the radical density in the reaction chamber.

[0008] Here, as a typical example, we have explained the case where precursor ions are dissociated by reacting with radicals. However, the same problems as those described above also occur when precursor ions are dissociated using other active particles such as ozone or metastable particles.

[0009] The problem to be solved by the present invention is to suppress the loss of active particles introduced into a reaction chamber in an ion analyzer that introduces precursor ions derived from sample components and active particles such as radicals into a reaction chamber and causes the two to react to generate and measure product ions.

[0010] The ion analyzer according to the present invention, which has been made to solve the above problems, comprises a reaction chamber into which precursor ions derived from sample components are introduced, at least a part of whose inner circumferential surface is formed of an insulating material, and an active particle introduction section which generates active particles from a raw material gas and introduces the active particles into the reaction chamber.

[0011] In conventional mass spectrometers, many of the active particles introduced into the reaction chamber recombine with metal atoms that make up the inner circumferential surface of the reaction chamber and are lost. In contrast, in the ion analyzer of the present invention, at least a portion of the inner circumferential surface of the reaction chamber is made of an insulator. The recombination coefficient between active particles and insulators is lower than the recombination coefficient between active particles and metals, so the probability that the active particles introduced into the reaction chamber will be lost even if they come into contact with molecules of the insulator that make up the inner circumferential surface of the reaction chamber is low. Therefore, the loss of active particles introduced into the reaction chamber can be reduced compared to conventional mass spectrometers.

[0012] FIG. 1 is a schematic configuration diagram of a mass spectrometer which is an embodiment of the ion analyzer according to the present invention. FIG. 2 is a cross-sectional view showing the schematic configuration of a radical generation unit in this embodiment. FIG. 3 is a diagram showing the structure of electrodes which constitute a multipole ion guide in a conventional mass spectrometer. FIG. 4 is a diagram showing the structure of electrodes which constitute a multipole ion guide in a mass spectrometer of this embodiment. FIG. 5 is a photograph of electrodes which constitute a multipole ion guide in a mass spectrometer of this embodiment. FIG. 6 is a diagram showing how electrodes of this embodiment are attached to an electrode holder. FIG. 7 is a view of the collision cell of this embodiment as seen from a direction along the ion optical axis. FIG. 8 is a diagram showing the results of measurements carried out to compare the reaction efficiency in a conventional mass spectrometer and the mass spectrometer of this embodiment. FIG. 9 is a diagram showing the structure of electrodes which constitute a multipole ion guide of another embodiment.

[0013] An embodiment of a mass spectrometer according to the present invention will now be described with reference to the drawings. In the drawings used in the following description, the scale of each component has been appropriately changed from the actual ratio, and some components have been omitted from the illustration, in order to make the configuration of the main components in this embodiment easier to understand.

[0014] <Schematic Configuration of Mass Spectrometer 1> Figure 1 shows the 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.

[0015] The mass spectrometer 1 of this embodiment has an ionization chamber 10 and a vacuum chamber 100. The ionization chamber 10 is maintained at approximately atmospheric pressure. The interior of the vacuum chamber 100 is divided into multiple 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 (a rotary pump and / or a turbomolecular pump, not shown), and has a multi-stage differential pumping system configuration in which the degree of vacuum increases sequentially from the ionization chamber 10, which is maintained at approximately atmospheric pressure, to the second analysis chamber 14, which is maintained at a high vacuum.

[0016] 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 by, for example, an LC column (not shown) is introduced into the ESI probe 101.

[0017] 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). The first intermediate vacuum chamber 11 is provided with an ion guide 111 that is made up 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 that focuses ions in the vicinity of the ion optical axis C.

[0018] 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 has an ion guide 121 arranged in the vicinity of the ion optical axis C, which is made up of a plurality of rod electrodes arranged to surround the ion optical axis C.

[0019] 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 that transports 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 and the multipole ion guide 133 each consist of multiple rod electrodes. The ion transport electrode 134 consists of multiple ring-shaped electrodes. The internal structure of the collision cell 132, including the multipole ion guide 133, will be described in detail later.

[0020] An opening 1321 for inserting the discharge tube 410 of the radical generation unit 4 is provided in the wall of the collision cell 132. The configuration of the radical generation unit 4 will be described later. A cylindrical tube connecting member 1322 is provided with one end surrounding 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 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 the flow path connecting the CID gas supply source 61 and the collision cell 132.

[0021] The collision cell 132 can perform two methods: a dissociation method in which precursor ions are dissociated by radicals such as oxygen radicals supplied from the radical generator 4; and a collision-induced dissociation (CID) method 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.

[0022] The second analysis chamber 14 is equipped with an ion transport electrode 141 for transporting ions incident from the first analysis chamber 13, an orthogonal acceleration unit 142 having a pair of pusher and puller electrodes arranged opposite each other across the ion optical axis C, an acceleration electrode 143 for accelerating ions sent out into the flight space by the orthogonal acceleration unit 142, a reflectron electrode 144 for forming a return trajectory of 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 or a multichannel plate.

[0023] The mass spectrometer 1 of this embodiment further includes a control / processing unit 7, an input unit 81, and a display unit 82. The control / processing unit 7 includes a memory unit 71. The memory 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 in accordance with instructions from a user, and measures samples and analyzes 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 running dedicated control / processing software installed on the computer on a processor.

[0024] 2 is a cross-sectional view of a main part, schematically illustrating the structure of the plasma generation unit 41 in the radical generation unit 4. The plasma generation unit 41 generates plasma of a raw material gas supplied from a raw material gas supply source 48, and introduces radicals generated in the plasma into the collision cell 132. The raw material gas may be, for example, water vapor, oxygen gas, nitrogen gas, dry air, or hydrogen gas. The microwave power supply 46 supplies power for generating plasma to a helical antenna 411 (described below). 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.

[0025] The plasma generating unit 41 includes a discharge tube 410 made of an insulating and dielectric material such as quartz or aluminum oxide, a helical antenna 411 that is a strip-shaped conductor wound helically around the discharge tube 410, an outer conductor 412 that is coaxial with the discharge tube 410 and has a cylindrical opening with an inner diameter slightly 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 located at the bottom of the casing 414. The helical antenna 411 is made of a metal such as copper, preferably a material similar to pure copper (e.g., oxygen-free copper or tough pitch copper) that has high conductivity and formability. Furthermore, its surface is preferably gold-plated to prevent oxidation.

[0026] The casing 414 is provided with a microwave supply connector 416. The casing 414 also includes a light source 417 that emits ultraviolet light into the discharge tube 410 and a photodetector 418 that detects the light emitted by the plasma generated inside the discharge tube 410. The light source 417 is turned on and 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 range is irradiated onto the discharge tube 410 made of quartz or aluminum oxide, electrons are emitted from the wall of the discharge tube 410. These electrons induce plasma. The light source 417 may be, for example, a UV-LED. The photodetector 418 is not sensitive to the wavelength range of light emitted from the light source 417, but is sensitive only to the wavelength range of light emitted from the plasma inside the discharge tube 410. The photodetector 418 may be, for example, a photodiode. The detection signal from the photodetector 418 is transmitted to the control and processing unit 7 and stored in the storage unit 71. The analysis execution unit 72 determines whether or not plasma is being generated by, for example, comparing the magnitude of the detection signal from the photodetector 418 with a predetermined threshold value.

[0027] 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 it where the helical antenna 411 is wound and where ultraviolet light is irradiated from the light source 417 is the radical generation chamber 4101, and the area downstream of that is the radical transport section 4102.

[0028] 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 portion 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 this connection point. The helical antenna 411, the outer conductor 412, the resonator adjustment mechanism 420, and other components 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 similar to that described in Patent Document 3, so 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.

[0029] In the plasma generating unit 41 of this embodiment, local inductively coupled discharge and electron cyclotron resonance are used to generate and maintain plasma. In this plasma generating unit 41, ECR can be used to increase the density of the plasma and stabilize it.

[0030] 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 a guide member 52 are inserted. The guide member 52 is a cylindrical member that is coaxial with the discharge tube 410 and arranged around 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 also provided at the tip of the guide member 52. The guide member 52 and the protector 53 are arranged around 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 tip of the portion of the discharge tube 410 exposed from the holding member 50 .

[0031] <Attaching the radical generation unit 4 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 wall surfaces of the vacuum chamber 100 and the collision cell 132, and a tube connection member 1322 is inserted into both openings. The tube connection member 1322 is a cylindrical member having a bottom surface with a through hole formed therein, and its bottom is attached to the opening 1321 of the collision cell 132. The diameter of the through hole formed in the bottom surface of the tube connection member 1322 is larger than the outer diameter of the discharge tube 410 and smaller than the outer diameter of the protector 53.

[0032] The operation of attaching the radical generation unit 4 to the collision cell 132 is the same as in the above-mentioned prior application, so a detailed explanation will be omitted, but in the radical generation unit 4, the outside of the discharge tube 410 is protected by a protector 53 until the tip of the discharge tube 410 enters the inside of the collision cell 132, thereby preventing the discharge tube 410 from being damaged when attaching the radical generation unit 4.

[0033] <Overview of Collision Cell 132> The structure of the electrode 1331 constituting the multipole ion guide 133 disposed in the collision cell 132 will be described with reference to FIGS. 3 to 7. FIG. 3 is a side view of an electrode 2331 (hereinafter also referred to as the "conventional electrode") constituting the multipole ion guide of a conventional mass spectrometer, and FIG. 4 is a side view of the electrode 1331 (hereinafter also referred to as the "electrode of this embodiment") constituting the multipole ion guide 133 of the mass spectrometer 1 of this embodiment. FIG. 5 is a photograph of the electrode of this embodiment used in an actual mass spectrometer. While FIG. 5 shows a photograph of four electrodes, in an actual device, as shown in FIG. 7, the multipole ion guide 133 is constituted by eight electrodes arranged around the ion optical axis C. As shown in FIG. 6, each electrode is attached to an electrode holder 1335 for use. Although eight electrodes are used in this embodiment, the ion guide 133 may also be constituted by four, six, ten, or more electrodes 1331.

[0034] The conventional electrode 2331 is a rectangular metal plate (for example, a stainless steel plate) with notches 2332 formed on both ends, and has a configuration similar to that described in Patent Document 5. The notches 2332 are the portions that are inserted into the electrode holder, and are attached inside the collision cell with the entire central portion 2333 exposed.

[0035] The electrode 1331 of this embodiment is formed by forming notches 1332 on both ends of a rectangular metal plate (for example, a stainless steel plate), and removing a part of a central portion 1333 exposed in the collision cell 132 (a portion 1334 excluding the side facing the ion optical axis C). In this embodiment, by removing the portions of the substrate, which is a substantially rectangular metal plate, other than the portion facing the ion optical axis C, the surface area is reduced compared to the substrate.

[0036] The electrode holder 1335 is made of an insulating material (e.g., a resin material or ceramic). Similar to the one described in Patent Document 5, the electrode holder 1335 has a disk shape with an opening in the center, and eight holes 1336 are formed on one side. The eight electrodes 1331 are positioned by inserting notches 1332 into these holes 1336. The electrode holder 1335 is fixed to the collision cell 132 by a mounting part (not shown).

[0037] 7, an insulating sheet material 1323 is attached to the inner peripheral surface of the collision cell 132. As a result, the surface of the metal (for example, aluminum) that constitutes the collision cell 132 is covered with an insulator.

[0038] Non-Patent Document 3 describes that oxygen recombines (disappears) on the surface of stainless steel 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. Non-Patent Document 4 shows that hydrogen radicals are more likely to disappear than oxygen radicals on the surface of an oxide. Non-Patent Document 5 describes that the recombination coefficients γ of hydrogen radicals and oxygen radicals for PTFE are both about 0.001.

[0039] Non-Patent Documents 3 to 5 indicate that radicals are easily lost when they come into contact with metal, and that reducing the opportunities for radicals to come into contact with metal is an effective way to prevent radical loss. Therefore, in the mass spectrometer 1 of this embodiment, an insulator (insulating sheet material 1323) is attached to the inner circumferential surface of the collision cell 132 to reduce the exposed metal area compared to conventional methods. Various resin materials, such as polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), polyimide (PI), and polybenzimidazole (PBI), can be suitably used for this insulator. In this embodiment, a polyimide sheet is used as the insulating sheet material 1323.

[0040] In addition, in this embodiment, by removing a portion of the central portion 1333 of the electrode 1331, the surface area of ​​the electrode 1331 (the surface area of ​​the portion exposed inside the collision cell 132, excluding the portion held by the electrode holder 1335 made of an insulating material) is also reduced.

[0041] In this embodiment, by adopting the above-described configuration, the chances of the radicals introduced into the collision cell 132 coming into contact with metal are reduced compared to conventional mass spectrometers. Therefore, the loss of radicals introduced into the collision cell 132 can be suppressed compared to conventional mass spectrometers.

[0042] Here, we will explain the results of measurements conducted by the present inventor to confirm the effect of reducing the surface area of ​​the electrode 1331 compared to conventional methods and covering the inner surface of the collision cell 132 with an insulating sheet material 1323, as in this embodiment. In this measurement, a conventional mass spectrometer (in which a multipole ion guide is configured with a conventional electrode 2331) and the mass spectrometer 1 of this embodiment (in which a multipole ion guide 133 is configured with the electrode 1331 of this embodiment) were used to perform oxygen attachment dissociation (OAD), in which oleic acid, which has one double bond, is irradiated with oxygen radicals to cause a reaction, and the intensities of the precursor ions and product ions were measured. The measurement conditions (such as the conditions for generating oxygen radicals) were the same for both measurements.

[0043] As described in Patent Document 2, when precursor ions derived from molecules having hydrocarbon chains containing unsaturated (double) bonds are reacted with oxygen radicals, the precursor ions can be dissociated at the unsaturated bond sites. In this measurement, the precursor ions dissociate at the single double bond in oleic acid, generating product ions. Therefore, the reaction efficiency of the precursor ions can be determined from the ratio of the intensity of the product ions to the intensity of the precursor ions. This reaction efficiency reflects the concentration of oxygen radicals in the collision cell 132.

[0044] The measurement results are shown in Figure 8. As shown in Figure 8, the precursor ion reaction efficiency was approximately 1% in the conventional mass spectrometer, whereas it was improved to approximately 10% in the mass spectrometer 1 of this embodiment. This reflects the fact that by covering the inner surface of the collision cell 132 with an insulator and configuring the multipole ion guide 133 using the electrode 1331 of the above embodiment, the loss of oxygen radicals due to contact with metal within the collision cell 132 is suppressed, resulting in an increased concentration of oxygen radicals within the collision cell 132. Furthermore, in the conventional mass spectrometer, radicals introduced near the exit of the collision cell are lost upon contact with the inner surface of the collision cell or the electrodes constituting the multipole ion guide. However, in the mass spectrometer 1 of this embodiment, radicals introduced into the collision cell 132 are not lost due to contact with metal and are uniformly dispersed throughout the entire interior of the collision cell 132.

[0045] In conventional mass spectrometers, when oxidizing radicals such as oxygen radicals are introduced, the radicals adhere to the electrode surface near the radical inlet, forming oxides, which can easily form an insulating oxide film locally on the electrode surface. When a voltage is applied to the electrode with an insulating oxide film locally formed on the electrode surface, charge buildup occurs, which can easily disrupt the electric field formed by the multipole ion guide, resulting in reduced ion transport efficiency and ion capture efficiency. In contrast, in the mass spectrometer 1 of this embodiment, the radicals introduced into the collision cell 132 are uniformly distributed throughout the entire interior of the collision cell 132, suppressing such disruption of the electric field due to local oxidation and improving ion transport efficiency and ion capture efficiency compared to conventional methods.

[0046] In addition, conventional methods clean electrodes by introducing reducing radicals, such as hydrogen radicals, into the collision cell to reduce and remove the insulating oxide film formed on the electrode surface. However, because the introduced radicals come into contact with the collision cell or the electrode surface near the radical inlet and are lost, the effect of removing the insulating oxide film remains near the radical inlet, making it difficult to fully restore the basic performance of the mass spectrometer. In contrast, in the mass spectrometer 1 of this embodiment, the radicals introduced into the collision cell 132 are uniformly distributed throughout the entire interior of the collision cell 132, cleaning the entire electrode and achieving the desired performance. The inventors conducted experiments in which hydrogen radicals were introduced into the collision cell 132 using a multipole ion guide 133 constructed with a copper electrode whose surface was entirely oxidized in both a conventional mass spectrometer and the mass spectrometer of this embodiment. In the conventional mass spectrometer, only the copper oxide on the electrode surface located near the radical inlet was reduced, whereas in the mass spectrometer 1 of this embodiment, copper oxide was reduced and removed throughout the entire electrode.

[0047] In the above embodiment, the surface area of ​​the electrode was reduced by removing the central portion of the substrate, but other methods can also be used. For example, as shown in FIG. 9 , the exposed metal area can be reduced by covering a portion of the central portion 2333 of a conventional electrode 2331 (the portion removed in the electrode 1331 of this embodiment) with an insulator 3337 (e.g., an insulating sheet material). Resin materials such as polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), polyimide (PI), and polybenzimidazole (PBI) can be suitably used for this insulator. Using such an electrode 3331 can achieve the same effects as using the electrode 1331 of the above embodiment.

[0048] The above embodiment is merely an example and can be modified as appropriate in accordance with the spirit of the present invention.

[0049] In the above embodiment, the inner peripheral surface of the metal collision cell 132 is covered with the insulating sheet material 1323, but it is also possible to attach insulating tape or sticker to the inner peripheral surface of the collision cell 132 (for example, Non-Patent Document 6), or to apply an insulating coating treatment (polyimide coating, fluororesin coating, etc.) to the inner peripheral surface of the collision cell 132 (for example, Non-Patent Documents 7 to 9). Alternatively, the collision cell 132 itself may be made of an insulating material (for example, ceramic).

[0050] In this embodiment, the multipole ion guide 133 is configured using electrodes 1331 with a smaller surface area than conventional ones, and at least a part of the inner circumferential surface of the collision cell 132 is covered with an insulator, but a configuration that satisfies both of these is a preferred embodiment and is not essential to the present invention. Even if only one of these configurations is provided, a sufficient effect of suppressing the loss of radicals in the collision cell 132 can be expected.

[0051] In the above embodiment, a mass spectrometer equipped with a Q-TOF mass separator was used, but any mass separator can be used. Furthermore, in the above embodiment, an ion source equipped with an ESI probe 101 that generates ions from a liquid sample was used, but other atmospheric pressure ion sources, such as an APCI probe, can also be used. Alternatively, an ion source that generates ions in a vacuum atmosphere can also be used. Furthermore, an ion source that generates ions from a gaseous or solid sample can also be used. Furthermore, in the above embodiment, a collision cell 132 was used to react precursor ions with radicals, but other reaction chambers, such as a three-dimensional ion trap, can also be used.

[0052] 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.

[0053] In the above embodiment, the radical generator 4 generates radicals from the source gas by inductively coupled plasma, but radicals may be generated from the source gas by capacitively coupled plasma. A similar configuration to the above can also be used in a mass spectrometer equipped with a radical generator that generates radicals by introducing a source gas into a heated discharge tube (e.g., Non-Patent Document 10).

[0054] In the above embodiment, precursor ions react with radicals. However, precursor ions can also be dissociated at specific positions by using active particles other than radicals, such as ozone or metastable particles. Since these active particles, like radicals, are easily lost upon contact with metals, the same effects as those described above can be achieved by employing the same configuration as in the above embodiment. Metastable particles refer to atoms (metastable atoms) or molecules (metastable molecules) in a long-lived excited state.

[0055] Aspects It will be apparent to those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0056] (Item 1) An ion analyzer according to one aspect of the present invention includes a reaction chamber, at least a portion of whose inner circumferential surface is formed of an insulating material, into which precursor ions derived from sample components are introduced, and an active particle introduction section, which generates active particles from a source gas and introduces the active particles into the reaction chamber.

[0057] In conventional mass spectrometers, many of the active particles introduced into the reaction chamber recombine with metal atoms constituting the inner circumferential surface of the reaction chamber and are lost. In contrast, in the ion analyzer according to paragraph 1, at least a portion of the inner circumferential surface of the reaction chamber is made of an insulator. The recombination coefficient between active particles and insulators is lower than the recombination coefficient between active particles and metals, so the probability that the active particles introduced into the reaction chamber will be lost even if they come into contact with molecules of the insulator constituting the inner circumferential surface of the reaction chamber is low. Therefore, the loss of active particles introduced into the reaction chamber can be reduced compared to conventional mass spectrometers.

[0058] (Item 2) The ion analyzer according to item 2 is the ion analyzer according to item 1, wherein the reaction chamber is configured by covering at least a portion of the inner surface of a cylindrical body made of metal with an insulating material.

[0059] The ion analyzer according to the second aspect can be easily constructed by simply covering the inner circumferential surface of a metal cylindrical body used in conventional mass analyzers with an insulating material.

[0060] (Clause 3) The ion analyzer according to paragraph 3 is the ion analyzer according to either paragraph 1 or paragraph 2, further comprising a multipole ion guide consisting of a plurality of electrodes arranged to surround an ion optical axis, which is the central axis of the flight path of ions in the reaction chamber, and the plurality of electrodes have a surface area reduced compared to that of a plate-shaped or columnar substrate by removing a portion of the substrate except for a portion facing the ion optical axis.

[0061] In the ion analyzer according to paragraph 3, by removing a portion of the roughly plate-shaped or roughly columnar substrate having the same shape as a conventional electrode, the surface area exposed to the reaction chamber can be reduced, reducing the chance of radicals coming into contact with metal and suppressing the loss of radicals.

[0062] (4) The ion analyzer according to 4 is the ion analyzer according to 1 or 2, further comprising a multipole ion guide consisting of a plurality of electrodes arranged to surround an ion optical axis, which is the central axis of the flight path of ions in the reaction chamber, and at least a portion of the surfaces of the plurality of electrodes, excluding the portion facing the ion optical axis, is covered with an insulator.

[0063] In the ion analysis device according to the fourth aspect, at least a portion of the surface of the conventionally used roughly plate-shaped or roughly columnar electrode, excluding the portion facing the ion optical axis, is covered with an insulator, thereby reducing the exposure of the metal portion in the reaction chamber and reducing the chance of radicals coming into contact with the metal, thereby suppressing the loss of radicals.

[0064] DESCRIPTION OF SYMBOLS 1...Mass spectrometer 10...Ionization chamber 100...Vacuum chamber 101...ESI probe 11...First intermediate vacuum chamber 12...Second intermediate vacuum chamber 13...First analysis chamber 132...Collision cell 1321...Opening 1322...Tube connection member 1323...Insulating sheet material 133...Multipole ion guide 1331...Electrode 1332...Cutout portion 1333...Central portion 1334...Cutout portion 1335...Electrode holder 1336...Hole 14...Second analysis chamber 3331...Electrode 3337...Insulator 4...Radical generation section 41...Plasma generation section 410...Discharge tube 4101...Radical generation chamber 411...Helical antenna 412...Outer conductor portion 413, 415...Permanent magnet 414...Casing 416...Microwave supply connector 417: Light source 418: Photodetector 420: Resonator adjustment mechanism 46: Microwave power supply 48: Source gas supply source 61: CID gas supply source 7: Control and processing unit 71: Storage unit 72: Analysis execution unit 81: Input unit 82: Display unit C: Ion optical axis

Claims

1. An ion analysis device comprising: a reaction chamber, at least a portion of whose inner circumferential surface is made of an insulating material, into which precursor ions derived from sample components are introduced; and an active particle introduction section that generates active particles from a source gas and introduces the active particles into the reaction chamber.

2. The ion analyzer according to claim 1, wherein the reaction chamber is formed by covering at least a part of the inner circumferential surface of a cylindrical body made of metal with an insulating material.

3. The ion analysis apparatus according to claim 1, further comprising a multipole ion guide consisting of a plurality of electrodes arranged to surround an ion optical axis which is the central axis of the flight path of ions in the reaction chamber, wherein the plurality of electrodes are formed by removing a portion of a plate-like or columnar base material except for a portion facing the ion optical axis, thereby reducing the surface area of ​​the base material.

4. The ion analysis apparatus according to claim 1, further comprising a multipole ion guide comprising a plurality of electrodes arranged to surround an ion optical axis which is the central axis of the flight path of ions in the reaction chamber, and at least a portion of the surfaces of the plurality of electrodes, except for the portions facing the ion optical axis, are covered with an insulator.

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