Mass analyzer

Abstract

To prevent breakage of an exit end of a capillary tube when the capillary tube is attached to / detached from a reaction chamber in a mass analyzer which generates radical inside the capillary tube and dissociates ion originating in a sample component by supplying the reaction chamber with the radial, the reaction chamber into which the ion is introduced.SOLUTION: A mass analyzer includes: a capillary tube 410 having a radical flow path inside; a reaction chamber 132 in which ion originating in a sample component is introduced; an opening 1321 which is provided on a wall surface of the reaction chamber and has a diameter larger than an external diameter of the capillary tube; a holding member 50 exposing an exit end of the capillary tube and holds the capillary tube; and a tube protective member 53 in which one end is fixed to the holding member and the other end reaches the exit end of the capillary tube and which is a cylindrical elastic member encircling an outer periphery of the capillary tube shrinkable in a lengthwise direction of the capillary tube and has an external diameter larger than the diameter of the opening.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a mass spectrometer, and more particularly to a mass spectrometer that dissociates ions using radicals generated from a source gas. [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 such as a collision cell, where the precursor ions are dissociated to generate various product ions that are then detected. Then, based on the partial structure information obtained from the mass-to-charge ratio of the detected product ions, the sample components are identified and the molecular structure of unknown components is estimated.

[0003] One method of dissociating precursor ions is known to involve the attachment of radicals such as hydrogen radicals, oxygen radicals, and nitrogen radicals (e.g., Patent Documents 1 to 3). For example, when a dissociation operation using radicals is performed on ions derived from a peptide, various types of 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] As radical generators used in such mass spectrometers, those described in Non-Patent Documents 1 and 2 are known. These radical generators include a capillary tube made of a dielectric material such as quartz or alumina, a helical antenna in which a conductive wire is wound in a three-dimensional spiral shape around the capillary tube, and a casing that is provided to surround the part of the outer periphery of the capillary tube around which the helical antenna is wound and holds the exposed outlet end of the capillary tube. Radicals are generated by supplying microwave power to the helical antenna and generating plasma in the raw material gas passing through the capillary tube due to the eddy current generated. The outlet end of the capillary tube exposed from the casing is inserted into a collision cell, and radicals generated inside the capillary tube are supplied to the collision cell from the outlet end of the capillary tube. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-191081 A [Patent Document 2] International Publication No. 2019 / 155725 [Patent Document 3] International Publication No. 2022 / 059247 [Non-patent literature]

[0006] [Non-Patent Document 1] Yuji Simabukuro and 4 others, "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 April 8, 2020], Doshisha University Academic Repository, Internet<URL: https: / / doors.doshisha.ac.jp / duar / repository / ir / 27819 / zk1079.pdf> [Non-Patent Document 3] Hidenori Takahashi and 6 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 Summary of the Invention [Problem to be solved by the invention]

[0007] In the radical generation unit, dirt forms inside the capillary tube as radicals are repeatedly generated. When dirt forms inside the capillary tube, impurities derived from the dirt flow into the collision cell together with the radicals, affecting the measurement results of MS / MS analysis. Therefore, it is necessary to remove the radical generation unit from the collision cell at appropriate times and clean and replace the capillary tube. In conventional radical generation units, the outlet end of the capillary tube is exposed from the casing, and there is a problem that the outlet end of the capillary tube is easily damaged by hitting the wall of the collision cell when attaching or detaching the radical generation unit to the collision cell.

[0008] Here, we have taken the example of a radical generator that generates plasma of the raw material gas to generate radicals, but the same problem as above also occurs when using a radical generator that generates radicals by introducing the raw material gas into a heated capillary tube (e.g., Non-Patent Document 3).

[0009] The problem that the present invention aims to solve is to prevent damage to the outlet end of a capillary tube when the capillary tube is attached to or detached from a reaction chamber in a mass spectrometer that generates radicals inside a capillary tube and dissociates the ions by supplying the radicals to a reaction chamber into which ions derived from sample components are introduced. [Means for solving the problem]

[0010] In order to solve the above problems, the mass spectrometer according to the present invention is a capillary tube having a radical flow path therein; a reaction chamber into which ions derived from sample components are introduced; an opening provided in a wall surface of the reaction chamber and having a diameter larger than an outer diameter of the capillary tube; a holding member for holding the capillary tube with an outlet end of the capillary tube exposed; a tube protection member having an outer diameter larger than the diameter of the opening, the tube protection member being a cylindrical elastic member having one end fixed to the holding member and the other end reaching the outlet end of the capillary tube, the elastic member being capable of shrinking in the longitudinal direction of the capillary tube and surrounding the outer periphery of the capillary tube; Equipped with. Effect of the Invention

[0011] In the mass spectrometer according to the present invention, radicals are supplied to a reaction chamber through a radical flow path inside a capillary tube. A holding member that holds the capillary tube with the outlet end of the capillary tube exposed and a tube protection member that is a cylindrical elastic member having one end fixed to the holding member and the other end reaching the outlet end of the capillary tube and that contracts in the length direction of the capillary tube are arranged on the outer periphery of the capillary tube. An opening for inserting the capillary tube is also formed in the reaction chamber.

[0012] When attaching a capillary tube to a reaction chamber in the mass spectrometer according to the present invention, the outlet end of the capillary tube is aligned with the position of the opening in the wall of the reaction chamber. At this time, since the outer periphery and the tip of the capillary tube are covered with the tube protection member, the capillary tube will not come into contact with the wall of the reaction chamber and be damaged. Since the diameter of the opening provided in the reaction chamber is larger than the outer diameter of the capillary tube and smaller than the outer diameter of the tube protection member, when the outlet end of the capillary tube is advanced further from the opening, the tube protection member contracts while abutting against the wall of the reaction chamber around the opening, and the capillary tube is exposed from the tip of the tube protection member and inserted into the reaction chamber. When removing the capillary tube, the outlet end of the capillary tube is pulled out from the opening of the reaction chamber and is simultaneously protected by the tube protection member. In this way, in the mass spectrometer according to the present invention, since the outlet end of the capillary tube is not exposed in a space other than the reaction chamber, it is possible to prevent the capillary tube from being damaged when attaching or detaching the capillary tube to or from the reaction chamber. [Brief description of the drawings]

[0013] [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] FIG. 4 is a side view showing a schematic configuration of a tip end of a radical generator in the present embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing a schematic configuration of a state in which a radical generation unit is attached to a collision cell in this embodiment. [Diagram 5] 5A to 5C are diagrams for explaining a procedure for mounting a radical generator in a collision cell in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] 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.

[0015] <Schematic configuration of mass spectrometer 1> 1 is a schematic diagram 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 also be used as a liquid chromatograph mass spectrometer by connecting a liquid chromatograph (LC) to the upstream stage.

[0016] As shown in Fig. 1, 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.

[0017] 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 sample liquid containing sample components separated in, for example, an LC column (not shown) is introduced into the ESI probe 101.

[0018] The ionization chamber 10 and the first intermediate vacuum chamber 11 are in communication with each other through a small-diameter desolvation tube 102. 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 the ion optical axis C and focuses ions in the vicinity of the ion optical axis C.

[0019] 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. In the second intermediate vacuum chamber 12, an ion guide 121 is arranged, which 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.

[0020] 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 are arranged along the ion optical axis C. The quadrupole mass filter 131 and the multipole ion guide 133 each consist of a plurality of rod electrodes. The ion transport electrode 134 consists of a plurality of ring-shaped electrodes.

[0021] An opening 1321 for inserting the capillary tube 410 of the radical generation unit 4 is provided on the wall surface of the collision cell 132. In addition, a cylindrical tube connection member 61 is provided so that one end surrounds this opening 1321. In the collision cell 132, ions are dissociated by radicals such as oxygen radicals supplied from the radical generation unit 4. The radical generation unit 4 will be described later. In addition to the radical generation unit 4, a gas supply unit for supplying a collision gas (usually an inert gas such as argon) for causing collision induced dissociation can also be connected to the collision cell 132 as necessary.

[0022] 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.

[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 controls the operations of the above-mentioned units, and has a function of receiving a detection signal from the ion detector 145 and executing predetermined data processing. 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 in the computer by a processor.

[0024] An example of a typical MS / MS analysis operation in the mass spectrometer 1 of this embodiment will be described.

[0025] The ESI probe 101 sprays the supplied liquid sample into the ionization chamber 10 while imparting an electric charge to the liquid sample. The sample components in the sprayed charged droplets are ionized as the droplets are broken down into fine droplets and the solvent evaporates. The generated ions derived from the sample components are sucked into the desolvation tube 102 by a gas flow formed by the pressure difference between the ionization chamber 10 and the first intermediate vacuum chamber 11 located on either side of the desolvation tube 102, and are sent to the first intermediate vacuum chamber 11. The ions that enter the first intermediate vacuum chamber 11 fly along the ion optical axis C, pass through the ion guide 111, the small holes of the skimmer 112, and the ion guide 121 in this order, and are sent to the first analysis chamber 13 and enter the quadrupole mass filter 131.

[0026] A voltage consisting of a superimposed DC voltage and a radio frequency voltage is applied from a power source (not shown) to the multiple rod electrodes constituting the quadrupole mass filter 131. Only ions (precursor ions) having a specific m / z value corresponding to this applied voltage selectively pass through the quadrupole mass filter 131 and enter the collision cell 132. Radicals are supplied to the collision cell 132 from the radical generator 4, and the precursor ions introduced into the collision cell 132 react with the radicals and dissociate. Various product ions generated by dissociation pass through the collision cell 132 while being converged by the action of the electric field formed by the multipole ion guide 133, and pass through the ion transport electrode 134 and ion transport electrode 141 in this order to enter the orthogonal acceleration section 142.

[0027] A pulse voltage is applied to the electrodes of the orthogonal acceleration unit 142 from a power source (not shown) at a predetermined timing. The application of this pulse voltage causes an electric field to be formed between the push electrode and the pull electrode, and the ions introduced into the orthogonal acceleration unit 142 are ejected in a direction substantially perpendicular to the ion optical axis C. The ions ejected from the orthogonal acceleration unit 142 are accelerated by the acceleration electrode 143 and introduced into a flight space in a flight tube 146. The ions then fly back in a reflected electric field formed by the reflectron electrode 144 and reach an ion detector 145. The flight time of the ions from the time they leave the orthogonal acceleration unit 142 to the time they reach the ion detector 145 depends on the speed of the ions, and the ion speed depends on the m / z value of the ions. The control and processing unit 7 creates a time-of-flight spectrum showing the relationship between the flight time and the ion intensity based on the detection signal obtained by the ion detector 145, and creates a mass spectrum by converting the flight time into an m / z value.

[0028] For example, when estimating the molecular structure of a sample component, the m / z value of the ion selected by the quadrupole mass filter 131 is set to the m / z value of a representative ion corresponding to the target sample component, and the product ions generated from the specific precursor ion are comprehensively detected while being separated according to their m / z values. In the mass spectrum (product ion spectrum) thus obtained, ions corresponding to various partial structures of the target sample component molecule are observed. The control and processing unit 7 can perform structure estimation of the sample component by analyzing such a mass spectrum.

[0029] <Schematic configuration of radical generating unit 4> Fig. 2 is a cross-sectional view of a main part, which shows a schematic structure of the plasma generating part 41 in the radical generating part 4. Fig. 3 is a side view showing the appearance of each member protecting the tip part of the capillary tube 410.

[0030] The plasma generating unit 41 generates plasma based on 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 source 46 supplies power for generating the plasma. The amount of raw material gas supplied from the raw material gas supply source 48 is adjusted by the valve 40 provided in the flow path connecting the raw material gas supply source 48 and the capillary tube 410.

[0031] The plasma generating unit 41 includes a capillary tube 410 made of quartz or aluminum oxide (or other dielectric material) which is an insulator and a dielectric, a helical antenna 411 which is a strip-shaped conductor (usually a metal such as copper) wound in a spiral shape around the capillary tube 410, an outer conductor part 412 which is coaxial with the capillary tube 410 and has a cylindrical opening whose inner diameter is slightly larger than the outer diameter of the capillary tube 410, a permanent magnet 413 embedded in the outer conductor part 412, a casing 414 which holds the outer conductor part 412, and a permanent magnet 415 which is disposed at the bottom of the casing 414. For the helical antenna 411, for example, a material (oxygen-free copper, tough pitch copper, etc.) close to pure copper which has high conductivity and formability is used. In addition, it is preferable that the surface of the helical antenna 411 is gold-plated to prevent oxidation.

[0032] 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 capillary tube 410 and a photodetector 418 that detects the light emission of plasma generated inside the capillary tube 410. The light source 417 is turned on / off based on a control signal transmitted from the control / processing unit 7. 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 capillary tube 410 made of quartz or aluminum oxide, electrons are emitted from the wall surface of the capillary tube 410. These electrons induce the ignition of plasma. For example, a UV-LED can be used for the light source 417. For the photodetector 418, one that is not sensitive to the wavelength band of light emitted from the light source 417 and is sensitive only to the wavelength band of light emitted from the plasma inside the capillary tube 410 is used. For example, a photodiode can be used for the photodetector 418. The detection signal of the photodetector 418 is transmitted to the control / processing unit 7. The control / processing unit 7 judges whether or not plasma has been ignited by, for example, comparing the magnitude of the detection signal of the photodetector 418 with a predetermined threshold value.

[0033] The capillary tube 410 is a raw material introduction tube into which raw material gas is introduced from a raw material gas supply source 48, and its inside becomes a plasma generation chamber and a radical flow path. The microwave supply connector 416 is a coaxial connector, and is connected to a microwave power source 46 via a coaxial cable. The conductive wire of the coaxial connector is connected to one end of a 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 resonator adjustment mechanism 420 has the same configuration as that described in Patent Document 3, so a detailed description of the configuration and operation will be omitted. A microwave power supply 46 provides power to the resonator via a coaxial cable and a microwave feed connector 416 .

[0034] The plasma generating unit 41 of this embodiment has a configuration called an ECR-LICP (Electron Cyclotron Resonance-Localized Inductively Coupled Plasma) type, which uses a local inductively coupled discharge and electron cyclotron resonance to generate and maintain plasma. In the ECR-LICP type plasma generating unit 41, the density of the plasma can be increased and stabilized by ECR.

[0035] 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 capillary tube 410. An opening is formed in the center of the magnet holder 51 through which the capillary tube 410 and the guide member 52 are inserted. The guide member 52 is a cylindrical member that is arranged coaxially with the capillary tube 410 and on the outer periphery of the capillary tube 410, and a compression spring 56 that expands and contracts in the axial direction of the capillary 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 capillary 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 capillary 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 capillary tube 410 that is exposed from the holding member 50 .

[0036] <Attachment of the radical generation unit 4 to the collision cell 132> 4 is a schematic cross-sectional view showing a configuration of a connection portion between the radical generation unit 4 and the collision cell 132 in a state where the radical generation unit 4 is attached to the collision cell 132. FIG. 5 is a schematic cross-sectional view showing a procedure for attaching the radical generation unit 4 to the collision cell 132.

[0037] 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 connection member 61 is inserted into the opening. The tube connection member 61 is composed of a bottom member with a through hole and a cylindrical member erected on the bottom member, and its bottom is attached to an opening 1321 provided in the wall of the collision cell 132. The diameter of the through hole formed in the bottom surface of the tube connection member 61 is larger than the outer diameter of the capillary tube 410 and smaller than the outer diameter of the protector 53. The inlet of the tube connection member 61 is formed in a tapered shape that widens toward the inlet end. The outer circumferential tip of the protector 53 is also formed in a tapered shape.

[0038] A seal joint 62 is inserted into the opening of the vacuum chamber 100. The seal joint 62 is a cylindrical part as a whole, and has a disk part extending outward from the outer periphery at the center in the longitudinal direction. The inlet of the seal joint 62 is formed in a tapered shape that widens toward the inlet end. The lower surface of the disk part of the seal joint 62 and the vacuum chamber 100 are sealed with an O-ring 63. The inner peripheral surface of the seal joint 62 and the outer peripheral surface of the tube connection member 61 are sealed with a Y-packing 64. Furthermore, with the radical generator 4 attached, the upper surface of the seal joint 62 and the magnet holder 51 are also sealed with an O-ring 65. This maintains the radical flow path from the capillary tube 410 to the collision cell 132 airtight.

[0039] When attaching the radical generator 4 to the collision cell 132, first, the capillary tube 410, the outer circumference and tip of which are covered with the guide member 52 and the protector 53, is inserted into the upper opening of the seal joint 62 (upper left in FIG. 5). At this time, since the opening on the inlet side of the seal joint 62 and the outer circumference tip of the protector 53 are both formed in a tapered shape, the tip of the protector 53 does not necessarily need to be inserted directly above the opening of the seal joint 62. As long as the tip of the protector 53 is inserted into the inlet of the seal joint 62, it is guided to the inlet of the tube connection member 61 located inside the seal joint 62 by the tapered parts of both. The inlet of the tube connection member 61 is also formed in a tapered shape that widens toward the inlet side, so when the protector 53 is further inserted, it is smoothly guided into the inside of the tube connection member 61.

[0040] As described above, the diameter of the through hole of the tube connection member 61 is larger than the outer diameter of the capillary tube 410 and smaller than the outer diameter of the protector 53. Therefore, when the capillary tube 410 is further advanced from the state where the capillary tube 410 and the like are inserted until the tip of the protector 53 reaches the bottom surface of the tube connection member 61 (upper right in FIG. 5), the tip of the protector 53 abuts against the bottom surface of the tube connection member 61 and does not advance any further, and the compression spring 56 contracts (lower left in FIG. 5). Then, only the capillary tube 410 advances into the inside of the collision cell 132 from the opening on the bottom surface of the tube connection member 61 (lower right in FIG. 5). In this way, the capillary tube 410 is inserted into the inside of the collision cell 132, and the radicals generated in the radical generation unit 4 are supplied to the collision cell 132 through the capillary tube 410.

[0041] Furthermore, when removing the radical generator 4 from the collision cell 132, the capillary tube 410 is pulled out from the collision cell 132 and the vacuum chamber 100 in the reverse order (lower right of Figure 5 → lower left of Figure 5 → upper right of Figure 5 → upper left of Figure 5).

[0042] In conventional radical generation units as described in Non-Patent Documents 1 and 2, the tip of the capillary tube was exposed, and so when the radical generation unit was attached to or detached from the collision cell for purposes such as replacing the capillary tube after long-term use, the outlet end of the capillary tube was easily damaged by hitting it against the wall of the collision cell.

[0043] In addition, the internal space of the vacuum chamber is evacuated, and gas for promoting collision-induced dissociation may be introduced into the collision cell 132. In addition, when radicals are supplied from the radical generator, it is necessary to prevent the radicals from leaking to the outside. In Non-Patent Documents 1 and 2, an O-ring or a V-ring is disposed between the inner circumference of the tube connection member provided in the collision cell and the outer circumference of the capillary tube to airtightly seal the flow path from the capillary tube to the collision cell. However, in this case, when removing the radical generator from the collision cell, a large frictional resistance occurs on the outer circumference of the capillary tube, and if an attempt is made to remove it by applying too much force, the capillary tube may be damaged.

[0044] In the prior application (Patent Application No. 2022-121645), the above problem was solved by disposing a seal joint between the main body of the radical generation unit and the collision cell, sealing the gap between them. However, this prior application also had a configuration in which the tip of the capillary tube was exposed, so it was necessary to carefully attach and detach the capillary tube when attaching and detaching the radical generation unit so as not to damage the capillary tube.

[0045] In contrast, in this embodiment, as described above, when the radical generator 4 is attached to or detached from the collision cell 132, the outer periphery and the tip of the capillary tube 410 are covered by the guide member 52 and the protector 53 in the space other than the inside of the collision cell 132. Therefore, it is possible to prevent the capillary tube 410 from being damaged when the capillary tube 410 is attached to or detached from the collision cell 132.

[0046] For example, in a mass spectrometer equipped with a time-of-flight mass separator as in this embodiment, the mass separator may be disposed so as to accelerate ions in the vertical direction. In that case, the collision cell 132 is located at a high place (for example, a height of a little more than 1 m) from the ground, and it is difficult to insert the capillary tube 410 from directly above the opening 1321 provided above the collision cell 132. In this embodiment, the inlet of the seal joint 62, the inlet of the tube connection member 61, and the outer circumferential tip of the protector 53 are all tapered. Therefore, even if the capillary tube 410 is inserted from directly above them at an angle, it is guided inward by the tapered inlet of the seal joint 62 and the tapered inlet of the tube connection member 61 in order. Therefore, even if the installation position of the radical generator 4 is at a high place, the capillary tube 410 can be easily and smoothly inserted into the collision cell 132.

[0047] In this embodiment, too, a seal joint 62 is provided, and a configuration is adopted in which the magnet holder 51 and the seal joint 62, the vacuum chamber 100 and the seal joint, and the tube connecting member 61 and the seal joint 62 are sealed, so that, as in the prior application, no frictional resistance is generated with respect to the capillary tube 410 when the radical generation unit 4 is attached or detached, and damage to the capillary tube 410 due to frictional resistance can be prevented.

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

[0049] The shapes of each part in the above embodiment, such as the radical generation unit 4, guide member 52, protector 53, compression spring 56, pipe connection member 61, seal joint 62, etc., are merely examples, and any suitable shape and material can be used as long as the functions described in the above embodiment can be realized.

[0050] 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 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.

[0051] In the above embodiment, the light source 417 is used to irradiate the capillary tube 410 made of quartz or aluminum oxide with ultraviolet light. However, the plasma may be generated without using the light source 417 .

[0052] In the above embodiment, a mass spectrometer equipped with a radical generation unit 4 that generates plasma of a raw material gas to generate radicals has been described. However, in a mass spectrometer equipped with a radical generation unit (e.g., Non-Patent Document 3) that generates radicals by introducing a raw material gas into a heated capillary tube, the radical generation unit can be attached and detached to a reaction chamber such as a collision cell using a similar configuration as described above.

[0053] [Aspects] It will be apparent to those skilled in the art that the above-described exemplary embodiments are illustrative of the following aspects.

[0054] (Section 1) A mass spectrometer according to one aspect of the present invention comprises: a capillary tube having a radical flow path therein; a reaction chamber into which ions derived from sample components are introduced; an opening provided in a wall surface of the reaction chamber and having a diameter larger than an outer diameter of the capillary tube; a holding member for holding the capillary tube with an outlet end of the capillary tube exposed; a tube protection member having an outer diameter larger than the diameter of the opening, the tube protection member being a cylindrical elastic member having one end fixed to the holding member and the other end reaching the outlet end of the capillary tube, the elastic member being capable of shrinking in the longitudinal direction of the capillary tube and surrounding the outer periphery of the capillary tube; Equipped with.

[0055] In the mass spectrometer according to paragraph 1, radicals are supplied to a reaction chamber through a radical flow path inside a capillary tube. A holding member for holding the capillary tube with the outlet end of the capillary tube exposed and a tube protection member for protecting the capillary tube, which is a cylindrical elastic member having one end fixed to the holding member and the other end reaching the outlet end of the capillary tube and contracts in the length direction of the capillary tube, are arranged on the outer periphery of the capillary tube. An opening for inserting the capillary tube is also formed in the reaction chamber.

[0056] When attaching the capillary tube to the reaction chamber in the mass spectrometer according to paragraph 1, the outlet end of the capillary tube is aligned with the position of the opening on the wall of the reaction chamber. At this time, since the outer periphery and the tip of the capillary tube are covered with the tube protection member, the capillary tube will not come into contact with the wall of the reaction chamber and be damaged. Since the diameter of the opening provided in the reaction chamber is larger than the outer diameter of the capillary tube and smaller than the outer diameter of the tube protection member, when the outlet end of the capillary tube is advanced further from the opening, the tube protection member contracts while abutting against the wall of the reaction chamber around the opening, and the capillary tube is exposed from the tip of the tube protection member and inserted inside the reaction chamber. When removing the capillary tube, the outlet end of the capillary tube is pulled out from the opening of the reaction chamber and is simultaneously protected by the tube protection member. In this way, in the mass spectrometer according to paragraph 1, since the outlet end of the capillary tube is not exposed in a space other than the reaction chamber, it is possible to prevent the capillary tube from being damaged when attaching or detaching the capillary tube to or from the reaction chamber.

[0057] (Section 2) The mass spectrometer according to paragraph 2 is the mass spectrometer according to paragraph 1, further comprising: a cylindrical tube connection member having an inner diameter shorter than the length of the capillary tube exposed from the holding member and larger than the opening, one end of which surrounds the opening; Equipped with.

[0058] (Section 3) The mass spectrometer according to paragraph 3 is a mass spectrometer according to paragraph 2, The inlet of the pipe connection member has a tapered shape that widens toward the inlet end.

[0059] For example, some mass spectrometers equipped with a time-of-flight mass separator have a configuration in which ions fly in a substantially vertical direction. In such a mass spectrometer, the collision cell is located at a high position above the ground, so that the work of attaching and detaching the radical generator to and from the collision cell is a high-altitude work, and it is difficult to accurately insert the capillary tube from directly above the opening. In the mass spectrometer according to the second paragraph, even in such a mass spectrometer, the capillary tube and the tube protection member are guided by the tube connecting member to easily align the capillary tube with the position of the opening in the wall of the reaction chamber. In addition, in the mass spectrometer according to the third paragraph, even if the capillary tube or the like is inserted from a tilted direction from directly above the tube connecting member, it is guided inward by the tapered portion of the inlet of the tube connecting member. Therefore, even if the installation position of the radical generator is at a high position or in a position that is difficult to see, the capillary tube can be smoothly inserted into the reaction chamber.

[0060] (Section 4) The mass spectrometer according to paragraph 4 is the mass spectrometer according to paragraph 2 or 3, further comprising: a vacuum chamber housing the reaction chamber; a cylindrical seal joint disposed between the vacuum chamber and the holding member; a first seal material that airtightly seals the holding member and the seal joint; a second seal material that airtightly seals the pipe connection member and the seal joint; a third sealant for air-tightly sealing the vacuum chamber and the seal joint; Equipped with.

[0061] According to the mass spectrometer of item 4, the flow path from the capillary tube to the reaction chamber is airtightly closed by the first seal, the second seal, and the third seal. Furthermore, since no frictional resistance is applied to the capillary tube when the capillary tube is attached or detached, damage to the capillary tube can be more reliably prevented. [Explanation of symbols]

[0062] 1...Mass spectrometer 100…Vacuum chamber 10…Ionization chamber 101…ESI probe 101…Probe 102...solvent removal tube 11…First intermediate vacuum chamber 111…Ion Guide 112…Skimmer 12...Second intermediate vacuum chamber 121…Ion Guide 13…1st analysis room 131...Quadrupole mass filter 132…Collision cell 1321…Aperture 133...Multipole ion guide 134...Ion transport electrode 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 41...Plasma generating section 410...Capillary tube 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 56…Compression spring 61...Pipe connection member 62…Seal joint 63, 65…O-ring 64...Y packing 7…Control and processing section 81...Input section 82...Display section C…Ion optical axis

Claims

1. A capillary tube having a radical flow path inside, A reaction chamber into which ions derived from sample components are introduced, An opening provided on the wall surface of the reaction chamber and having a diameter larger than the outer diameter of the capillary tube, A holding member that exposes the outlet end of the capillary tube and holds the capillary tube, A cylindrical elastic member that surrounds the outer periphery of the capillary tube, one end of which is fixed to the holding member and the other end reaches the outlet end of the capillary tube and is contractible in the longitudinal direction of the capillary tube, and has an outer diameter larger than the diameter of the opening, and is a tube protection member A mass spectrometer comprising.

2. Furthermore, A tubular tube connection member having an inner diameter larger than the opening and surrounding the opening at one end The mass spectrometer according to claim 1, comprising.

3. The mass spectrometer according to claim 2, wherein the inlet of the tube connection member has a tapered shape that widens toward the inlet end.

4. Furthermore, A vacuum chamber that houses the reaction chamber, A cylindrical seal joint disposed between the vacuum chamber and the holding member, A first sealing material that hermetically seals the holding member and the seal joint, A second sealing material that hermetically seals the tube connection member and the seal joint, A third sealing material that hermetically seals the vacuum chamber and the seal joint, The mass spectrometer according to claim 2, comprising.

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