Mass spectrometer and method for adjusting mass spectrometer

Abstract

To simply and accurately adjust a resonator in a radical generating portion.SOLUTION: A mass spectrometer according to an embodiment of the present invention is a mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation includes a radical generation chamber (400), an antenna for supplying high-frequency power to the inside of the radical generation chamber, an impedance adjustment unit that adjusts an impedance of the antenna according to operator's operation, and a raw material gas supply unit that supplies a raw material gas to the inside of the radical generation chamber, and further includes a radical generation unit (4, 40) that generates radical species from the source gas by supplying the source gas and the high-frequency power to the radical generation chamber and generating plasma in the radical generation chamber, and an information providing unit (148, 46, 47) that generates an electrical signal reflecting a plasma generation state inside the radical generation chamber and providing visual or audible information to the operator on the basis of the electrical signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mass spectrometer and a method for adjusting a mass spectrometer, and more particularly to a mass spectrometer that performs dissociation operations on ions using radical species, and a method for adjusting the mass spectrometer. [Background technology]

[0002] Mass spectrometers are known that dissociate ions derived from sample components by attaching radical species such as hydrogen radicals, oxygen radicals, and nitrogen radicals to the ions, and then perform mass analysis of the resulting product ions (see, for example, Patent Document 1). For example, by performing a dissociation operation using such radical species on ions derived from a peptide, various types of product ions that reflect the structure of the peptide, such as its amino acid sequence, can be generated. By analyzing the mass spectrum in which such various product ions are observed, the structure of the peptide can be deduced.

[0003] There are several types of radical generators for generating radical species. However, it is preferable that the radical generator installed in the mass spectrometer described above be as small and lightweight as possible. Examples of such radical generators include those described in Non-Patent Documents 1 and 2. In this radical generator, microwave power is supplied to a conductive antenna (spiral antenna) wound helically around a capillary tube made of a dielectric material such as quartz. Eddy currents are then used to generate plasma within the capillary tube, generating radical species. Furthermore, a magnet is placed outside the capillary tube, and the magnetic field generated by this magnet is used to increase and stabilize the plasma density through the electron cyclotron resonance (ECR) phenomenon. Because this radical generator utilizes localized inductive discharge and resonant cyclotron resonance to generate and maintain plasma, it is referred to as an ECR-LICP (Electron Cyclotron Resonance-Localized Inductively Coupled Plasma) type. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-191081 [Patent Document 2] International Publication No. 2019 / 155725 [Non-patent literature]

[0005] [Non-Patent Document 1] Yuji Simabukuro and four 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] Hidenori Takahashi and 7 others, "Identifying Double Bond Positions in Phospholipids Using Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry Based on Oxygen Attachment Dissociation," Mass Spectrometry, 2020, Vol. 8, Issue 2, pp. S0080 Summary of the Invention [Problem to be solved by the invention]

[0006] In the ECR-LICP type radical generator described above, a roughly cylindrical outer conductor is provided coaxially with the spiral antenna and is grounded. A conductive component is inserted into the gap between a suitable longitudinal portion of the spiral antenna and the outer conductor, electrically connecting that portion of the spiral antenna to the outer conductor, which is at ground potential. This determines the impedance of the spiral antenna (i.e., the impedance at the feeding point), and an ECR resonant circuit including that impedance is formed.

[0007] In such radical generators, the longitudinal position of the spiral antenna electrically connected to the outer conductor must be adjusted for each device in order to adjust the impedance of the spiral antenna so that appropriate resonance occurs in the ECR resonant circuit. Hereinafter, this impedance adjustment will be referred to as matching adjustment. If this matching adjustment is not performed appropriately, the power radiated from the spiral antenna will be insufficient, and a high-frequency electric field of sufficient strength to generate plasma will not be formed, which may result in reduced radical generation or no radical generation at all. Therefore, in mass spectrometers using such radical generators, matching adjustment must be performed before and / or after incorporating the radical generator into the device.

[0008] The present invention solves these problems, and its main object is to provide a mass spectrometer and a method for adjusting a mass spectrometer that can easily and accurately perform matching adjustment for plasma generation in a radical generation device, that is, to generate a sufficient amount of radical species. [Means for solving the problem]

[0009] One aspect of the mass spectrometer according to the present invention is a mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation, a radical generation unit including: a radical generation chamber; an antenna for supplying high frequency power to the inside of the radical generation chamber; an impedance adjustment unit for adjusting the impedance of the antenna in response to an operation by an operator; and a raw material gas supply unit for supplying a raw material gas to the inside of the radical generation chamber, the radical generation unit supplying the raw material gas and the high frequency power to the inside of the radical generation chamber and generating plasma in the inside of the radical generation chamber to generate radical species from the raw material gas; an information providing unit that generates an electric signal that reflects the state of plasma generation inside the radical generation chamber and provides visible or audible information based on the electric signal to an operator; Equipped with.

[0010] Furthermore, one aspect of a method for adjusting a mass spectrometer according to the present invention is a method for adjusting a mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation, the method comprising: a radical generation step of supplying a source gas to a radical generation chamber and supplying high-frequency power via an antenna to generate plasma inside the radical generation chamber, thereby generating radical species from the source gas; an information providing step of generating an electric signal reflecting the state of plasma generation inside the radical generation chamber and providing visible or audible information based on the electric signal to an operator; an adjusting step of adjusting the impedance of the antenna in response to an operation by an operator in accordance with the provided visual or audible information; It has.

[0011] Another aspect of the mass spectrometer according to the present invention is a mass spectrometer comprising a radical generation unit that generates radical species, dissociates ions using the radical species, and analyzes the ions generated by the dissociation, wherein the radical generation unit: a radical generation chamber; a source gas supply unit that supplies a source gas that serves as a source of radical species into the radical generation chamber; an antenna for supplying high frequency power to the inside of the radical generation chamber; an impedance adjustment unit that adjusts the impedance of the antenna by changing the ground point of the antenna in response to a movement of an operator; a position indicator having a scale along the direction of movement of the operator; Includes. [Effects of the Invention]

[0012] According to the above aspects of the mass spectrometer and the method for adjusting a mass spectrometer of the present invention, matching adjustment for generating radical species in the radical generation unit can be performed simply and accurately, that is, so that a sufficient amount of radical species is generated. This reduces the effort and time required to adjust the radical generation unit, for example, during the manufacturing or adjustment stage of the mass spectrometer or during maintenance of the mass spectrometer, and reduces the costs involved. Furthermore, by accurately adjusting the radical generation unit, a sufficient amount of radical species can be stably supplied, allowing ions derived from a target sample to be dissociated with high efficiency, thereby fully demonstrating analytical performance such as detection sensitivity. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing the overall configuration of a mass spectrometer according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic cross-sectional view of a main body of the radical production unit in the mass spectrometer of the present embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional perspective view of a main body of the radical generating unit shown in FIG. 2. [Figure 4] FIG. 3 is an enlarged cross-sectional view of a main body of the radical generating unit shown in FIG. 2. [Figure 5] 3 is a perspective, partially cross-sectional view showing the structure of a resonator adjustment mechanism included in the radical generating unit shown in FIG. 2. FIG. [Figure 6] FIG. 10 is a diagram showing the overall configuration of a mass spectrometer according to a modified example of the embodiment. [Figure 7] FIG. 10 is a diagram showing the overall configuration of a mass spectrometer according to another embodiment of the present invention. [Figure 8]FIG. 1 shows the difference in mass spectrum between precursor ions derived from phospholipids having unsaturated bonds irradiated with oxygen radicals and those irradiated without oxygen radical irradiation. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mass spectrometer and an adjustment method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0015] Figure 1 is a schematic diagram of a mass spectrometer according to one embodiment of the present invention. This mass spectrometer is a quadrupole time-of-flight (Q-TOF) mass spectrometer equipped with an atmospheric pressure ion source. This mass spectrometer is often connected to a liquid chromatograph (LC) in the upstream stage and used as a liquid chromatograph mass spectrometer.

[0016] As shown in Figure 1, this mass spectrometer has an ionization chamber 10 and a vacuum chamber 1. The inside of the ionization chamber 10 is at approximately atmospheric pressure. The inside of the vacuum chamber 1 is divided into multiple compartments (four compartments in this example), and each compartment is evacuated by a vacuum pump (a rotary pump and / or a turbomolecular pump, not shown), forming a first intermediate vacuum chamber 11, a second intermediate vacuum chamber 12, a first analysis chamber 13, and a second analysis chamber 14. In other words, this mass spectrometer has a multi-stage differential pumping system configuration in which the degree of vacuum increases in order from the ionization chamber 10, which is at approximately atmospheric pressure, to the second analysis chamber 14, which is at a high vacuum.

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

[0018] The ionization chamber 10 and the first intermediate vacuum chamber 11 are connected via a small-diameter desolvation tube 102. The first intermediate vacuum chamber 11 is provided with an ion guide 111, which is made up of multiple ring-shaped electrodes with different diameters and focuses ions in the vicinity of an ion optical axis C, which is the central axis of the ion passageway.

[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. The second intermediate vacuum chamber 12 is provided with an ion guide 121 which is made up of a plurality of rod electrodes arranged to surround the ion optical axis C and which focuses ions in the vicinity of the ion optical axis C.

[0020] In the first analysis chamber 13, there are arranged along the ion optical axis C: 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 guide 134 that transports ions ejected from the collision cell 132. The ion guide 134 is composed of multiple ring-shaped electrodes of the same diameter.

[0021] The collision cell 132 is connected to the radical generation unit 4. The collision cell 132 has the function of dissociating ions using radical species such as oxygen radicals supplied from the radical generation unit 4. The radical generation unit 4 will be described in detail later. In addition to the radical generation unit 4, the collision cell 132 can also be connected to a gas supply unit that supplies a collision gas (usually an inert gas such as argon) for causing collision-induced dissociation.

[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 section 142 including a pair of push-out and pull-in electrodes arranged opposite each other across the ion incident optical axis (orthogonal acceleration region), an acceleration electrode 143 for accelerating ions sent out into the flight space by the orthogonal acceleration section 142, a reflector 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 or a multichannel plate.

[0023] This mass spectrometer also includes a control and processing unit 5, an input unit 6, and a display unit 7. The control and processing unit 5 controls the operation of each unit, and has the function of receiving detection signals from the ion detector 145 and performing predetermined data processing. Generally, the control and processing unit 5 is configured as a general-purpose personal computer (PC), and the desired functions are realized by running dedicated control and processing software installed on the computer. A typical MS / MS analysis operation in this mass spectrometer will now be briefly described.

[0024] The ESI probe 101 sprays a 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 finer droplets and the solvent evaporates. The generated ions derived from the sample components are sucked into the desolvation tube 102 by a gas flow created by the pressure difference between both ends of the desolvation tube 102 and sent to the first intermediate vacuum chamber 11. The ions that enter the first intermediate vacuum chamber 11 travel generally along the ion optical axis C, pass through the ion guide 111, the small holes in the skimmer 112, and the ion guide 121, and are sent to the first analysis chamber 13 and introduced into the quadrupole mass filter 131.

[0025] A voltage obtained by adding together a DC voltage and an RF voltage is applied from a power supply (not shown) to the multiple rod electrodes that make up the quadrupole mass filter 131. Only ions having a specific m / z value corresponding to this applied voltage selectively pass through the quadrupole mass filter 131 and are introduced into the collision cell 132. Radical species are supplied into the collision cell 132 from the radical generator 4, and ions introduced into the collision cell 132 (generally referred to as precursor ions) react with the radical species and dissociate. Various product ions generated by dissociation are converged by the action of the electric field formed by the multipole ion guide 133, exit the collision cell 132, pass through the ion guide 134 and the ion transport electrode 141, and are introduced into the orthogonal accelerator 142.

[0026] A pulse voltage is applied to the electrodes of the orthogonal acceleration unit 142 from a power supply (not shown) at a predetermined timing, causing the ions introduced into the orthogonal acceleration unit 142 to be ejected in a direction substantially perpendicular to the ion optical axis C. The ejected ions are accelerated by the acceleration electrode 143 and introduced into a flight space within the flight tube 146. The ions are deflected by an electric field formed by the reflector electrode 144 and reach the ion detector 145. The ion detector 145 outputs a detection signal corresponding to the amount of incident ions to the control and processing unit 5. The flight time of an ion from the time it leaves the orthogonal acceleration unit 142 to the time it reaches the ion detector 145 depends on the velocity of the ion, and this ion velocity depends on the m / z value of the ion. Therefore, the control and processing unit 5 creates a time-of-flight spectrum showing the relationship between flight time and ion intensity based on the detection signal obtained by the ion detector 145, and converts the flight time into an m / z value to create a mass spectrum.

[0027] For example, if one wishes to perform structural analysis of a known sample component, the m / z value of the ions 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 product ions generated from that specific precursor ion are comprehensively detected while being separated according to their m / z values. The resulting mass spectrum (product ion spectrum) contains ions corresponding to various substructures of the target sample component molecule. The control and processing unit 5 can then analyze the mass spectrum to estimate the structure of the sample component.

[0028] Next, the configuration and operation of the radical generator 4 that supplies radical species to the collision cell 132 will be described. 1, the radical generation unit 4 is the above-mentioned ECR-LICP type radical generation device, and includes a main body 40 including a radical generation chamber 400, a raw material supply unit 42, and a microwave power supply 43. A valve 41 for adjusting the flow rate of the raw material gas is provided in the flow path from the raw material supply unit 42 to the radical generation chamber 400. In this example, the radical generation unit 4 also includes a display processing unit 46 and a display unit 47.

[0029] Fig. 2 is a schematic cross-sectional view showing the structure of main body 40. Fig. 3 is a schematic cross-sectional perspective view of a portion of main body 40. Fig. 4 is an enlarged cross-sectional view of a portion of main body 40. Fig. 5 is a partial cross-sectional perspective view showing the structure of a resonator adjustment mechanism, which is part of main body 40.

[0030] The main body 40 generates plasma from a raw material gas supplied from a raw material supply unit 42, and sends radical species generated in the plasma to the outside, specifically to the collision cell 132. The microwave power supply 43 supplies microwave power for generating the plasma. In this case, the raw material gas is, for example, water vapor.

[0031] The main body 40 includes a central cylindrical tube 410 made of quartz (or other dielectric material), which is an insulator and a dielectric; a spiral antenna 411, which is a strip-shaped conductor (usually metal) wound helically around the central cylindrical tube 410; an outer conductor 412 made of a conductor, coaxial with the central cylindrical tube 410, and having a cylindrical opening whose inner diameter is slightly larger than the outer diameter of the central cylindrical tube 410; magnets 413 and 415 embedded in the outer conductor 412; a first casing 414 that holds the outer conductor 412; a microwave supply connector 416 attached to the first casing 414; and a resonator adjustment mechanism 420 including an inner tube 421 and an outer tube 424 (described later). The spiral antenna 411 is made of, for example, a material similar to pure copper (such as oxygen-free copper or tough-pitch copper), which has high conductivity and formability. It is preferable that its surface be gold-plated to prevent oxidation.

[0032] The interior of the central cylindrical tube 410 serves as both a source gas introduction tube and a radical generation chamber. Specifically, the internal space of the central cylindrical tube 410, including the portion around which the spiral antenna 411 is wound and its vicinity, constitutes the radical generation chamber 400. The microwave supply connector 416 is a coaxial connector and is connected to the microwave power supply 43 via a coaxial cable (not shown). The conductive wire of the coaxial connector is connected to one end of the spiral antenna 411. The outer conductor 412 is also grounded (not shown). As will be described later, a portion of the spiral antenna 411 and the outer conductor 412 are electrically connected via a resonator adjustment mechanism 420, and the connection point is the ground point of the spiral antenna 411. The spiral antenna 411, the outer conductor 412, the resonator adjustment mechanism 420, etc. constitute an ECR resonator. The microwave power supply 43 supplies power to this resonator via the coaxial cable and the microwave supply connector 416.

[0033] Furthermore, a light source 417 that irradiates the central cylindrical tube 410 with light of a predetermined wavelength and a photodetector 418 are provided in the first casing 414 at a position facing the radical generation chamber 400. The photodetector 418 detects light of a predetermined wavelength band that includes the wavelength of light emitted from the plasma in the radical generation chamber 400. The photodetector 418 is preferably insensitive to the light emitted from the light source 417. In this example, an LED light source that emits deep ultraviolet light is used as the light source 417, and a photodiode that is sensitive to the visible light range (and does not detect ultraviolet light) is used as the photodetector 418. This allows the photodetector 418 to detect the light emitted from the plasma without being affected by the light emitted from the light source 417. However, the photodetector 418 may be any device that can obtain a measurement value corresponding to the intensity of incident light. For example, a phototransistor that operates similarly to a photodiode or a photoresistor using CdS (cadmium sulfide), whose resistance value changes according to the intensity of incident light, may be used as the photodetector 418.

[0034] In the main body 40, a cylindrical second casing 440 having approximately the same outer diameter as the outer conductor 412 and the first casing 414 is detachably attached to the upper part of the outer conductor 412. The second casing 440 has an opening 441 formed therein through which an operator can insert their fingers to operate a fixed knob 423 and a movable knob 425 (described later) that are provided to surround the central cylindrical tube 410. Furthermore, on the outer peripheral surface of the second casing 440, on the side of the opening 441, scales 442 are drawn at predetermined intervals along the extension direction of the central cylindrical tube 410.

[0035] A transport pipe 44 for transporting the radicals generated in the radical generation chamber 400 to the collision cell 132 is connected to the outlet end of the central cylindrical tube 410 of the main body 40 via a valve 45. The transport pipe 44 is an insulating tube, and for example, a quartz glass tube or a borosilicate glass tube can be used.

[0036] In this radical generator 4, radical species are generated as follows. The raw material supply unit 42 supplies the raw material gas to the central cylindrical tube 410. The microwave power supply 43 supplies a microwave current having a center frequency in the range of, for example, 2.4 GHz to 2.5 GHz to the spiral antenna 411. Next, while the microwave power supply 43 supplies microwave power to the raw material gas in the radical generation chamber 400, the light source 417 irradiates the central cylindrical tube 410 with deep ultraviolet light. When exposed to the deep ultraviolet light, electrons are emitted from the wall of the central cylindrical tube 410, and these electrons generate plasma from the raw material gas in the radical generation chamber 400. At this time, if the resonator is adjusted by the resonator adjustment mechanism 420 so that the electron cyclotron frequency of electrons moving around the magnetic field generated by the magnets 413 and 415 matches the microwave frequency, the plasma density increases and stabilizes due to ECR. Then, radical species such as oxygen radicals in the plasma move through the central cylindrical tube 410 as new raw material gas is introduced and are emitted from the open end at the end.

[0037] The structure of the resonator adjustment mechanism 420 and the adjustment procedure using it are as follows. As shown in FIG. 3, the resonator adjustment mechanism 420 includes an inner cylinder 421 and an outer cylinder 424, which are coaxial double cylindrical tube structures, and a movable knob 425. The inner cylinder 421 is longer than the outer cylinder 424 by a predetermined length. Both the inner cylinder 421 and the outer cylinder 424 are elastically deformable components, and are preferably made of a copper alloy for springs (such as beryllium copper or phosphor bronze). Furthermore, to reduce contact resistance, it is preferable to gold-plate the surfaces of the inner cylinder 421 and the outer cylinder 424. For convenience, the ends of the inner cylinder 421 and the outer cylinder 424 that are inserted first into the central cylindrical tube 410 (the lower ends in FIG. 3) will be referred to as the tip, and the opposite ends will be referred to as the base.

[0038] As shown in Fig. 5, the tip of inner tube 421 is divided into multiple pieces (four in this example) by slits 421a parallel to the axis, forming divided pieces 421b. At the tip of each divided piece 421b, a tapered portion 421c is formed, which gradually bulges outward from the base side toward the tip. Also, as shown in Fig. 3, fixed knob 423 is attached to the base of inner tube 421, and a male thread portion 422 is provided on the outer periphery of inner tube 421, extending over a predetermined length in the axial direction from the end connected to fixed knob 423.

[0039] On the other hand, like the inner cylinder 421, the tip of the outer cylinder 424 is also divided into multiple pieces (four in this example) by slits 424a parallel to the axis to form divided pieces 424b. Each divided piece 421b, 424b at the tip of the inner cylinder 421 and the outer cylinder 424 functions as an independent leaf spring. The movable knob 425 has a through hole on its inner circumferential surface, and a female screw portion that screws onto the male screw portion 422 of the inner cylinder 421.

[0040] 3 and 5, the movable knob 425 is attached so as to be threaded onto the male thread portion 422 of the inner tube 421, and the inner tube 421 is inserted into the outer tube 424. When inserting the inner tube 421 into the outer tube 424, the divided pieces 421b can be elastically deformed inward so that the tapered portion 421c does not become an obstacle.

[0041] 3, the worker gradually advances inner cylinder 421 and outer cylinder 424 of resonator adjustment mechanism 420, which are integrated, into gap 431 between spiral antenna 411 around central cylindrical tube 410 and the inner circumferential surface of outer conductor 412. At this time, divided pieces 421b, 424b of inner cylinder 421 and outer cylinder 424 are not elastically deformed, and the inner circumferential surface of inner cylinder 421 is smoothly inserted while maintaining a very small gap with spiral antenna 411, and the outer circumferential surface of outer cylinder 424 rubs against the inner circumferential surface of outer conductor 412.

[0042] As shown in Figure 4, when the tip of the outer cylinder 424 is in contact with the tapered portion 421c of the inner cylinder 421, the spiral antenna 411 is grounded at the contact point of the elastically deformed inner cylinder 421. If the grounding position of the spiral antenna 411 changes in the axial direction, the impedance of the antenna 411 changes, and the resonance state changes. This changes the state of the generated plasma. Therefore, the operator moves the entire resonator adjustment mechanism 420 to change the grounding position of the spiral antenna 411 and finds a position where plasma is generated well, that is, a position where matching adjustment is properly performed.

[0043] Whether the matching is appropriate can be confirmed by observing the state of plasma emission when the source gas and microwave power are supplied to the radical generation chamber 400. However, for example, discharge plasma of OH radicals contains a 309 nm ultraviolet spectrum that may be harmful to the human eye, making visual confirmation undesirable. In contrast, the mass spectrometer of this embodiment is provided with an adjustment monitor including a photodetector 147, a display processor 46, and a display unit 47. In this example, the display unit 47 is, for example, a 7-segment LED display with a predetermined number of digits. The display processor 46 and the display unit 47 may be attached to the main body 40 itself or may be separate from the main body 40.

[0044] That is, during plasma generation, the photodetector 418 continuously or intermittently measures the intensity of light of a predetermined wavelength emitted from the radical generation chamber 400. The display processing unit 46 converts the current signal from the photodetector 418 into a voltage signal, digitizes the voltage value, and drives the display unit 47. As a result, the display unit 47 displays a voltage value that reflects the intensity of the light received by the photodetector 418 as a numerical value. Therefore, the operator can visually check this numerical value and adjust the ground position of the spiral antenna 411 so that the numerical value is as large as possible or so that it is larger than a predetermined reference value.

[0045] Once the optimal grounding position for spiral antenna 411 has been found, the operator rotates movable knob 425 while holding fixed knob 423 to fix the position of inner cylinder 421. This causes movable knob 425 to push the base of outer cylinder 424, advancing outer cylinder 424 axially relative to inner cylinder 421. As shown in FIGS. 4 and 5 , the tip of segment 424b of outer cylinder 424 abuts against and pushes tapered portion 421c of inner cylinder 421, causing segment 421b of inner cylinder 421 to elastically deform inward. Conversely, segment 424b of outer cylinder 424 elastically deforms outward. As a result, segment 421b of inner cylinder 421 comes into close contact with spiral antenna 411, and segment 424b of outer cylinder 424 comes into close contact with the inner circumferential surface of outer conductor 412. Furthermore, because divided pieces 421b and 424b are pressed by spiral antenna 411 and outer conductor portion 412, divided piece 421b of inner cylinder 421 and divided piece 424b of outer cylinder 424 also adhere tightly to each other.

[0046] In this way, good electrical connection is established at each contact surface, and the axial contact position is fixed, so plasma continues to be generated well. To readjust the resonator, simply turn the movable knob 425 in the opposite direction to move the outer cylinder 424 back in the axial direction relative to the inner cylinder 421 (pull it up in Figures 2 and 4).

[0047] The display unit 47 does not have to show the voltage value, current value, etc. numerically, and any other suitable display device can be used, such as a bar-shaped level indicator that shows the voltage value or current value level by the length or color of the bar. Furthermore, the display unit 47 may not only display the voltage or current value, but also notify the operator of the light intensity by sound. In this case, for example, a buzzer that changes sound depending on the voltage value can be used.

[0048] As described above, in the mass spectrometer of this embodiment, the operator can use the resonator adjustment mechanism 420 to perform matching adjustment in the ECR resonator of the radical generation unit 4 so that plasma is generated well, that is, so that radical species are generated efficiently, without having to directly and visually check the plasma light emission state.

[0049] In particular, display using numerical values ​​allows adjustment to be made according to quantitative standards without relying on the subjective judgment of the operator. Furthermore, by recording the voltage value at the end of adjustment, it is possible to easily grasp the deterioration state of the radical generator 4 as the device is used, or the deviation of adjustment due to maintenance of the device. Of course, the display processing unit 46 may also be provided with a storage unit that stores numerical values ​​such as the voltage value at the time instructed by the operator.

[0050] Furthermore, in the mass spectrometer of this embodiment, it is also possible to perform matching adjustment as follows. Both the fixed knob 423 and the movable knob 425 move linearly in the extension direction (axial direction) of the central cylindrical tube 410, and their positions in the axial direction change depending on the contact position between the spiral antenna 411 and the outer conductor portion 412. Therefore, a range of positions of the fixed knob 423 and / or the movable knob 425 that allows plasma to be generated that can generate a sufficient amount of radicals (for example, a predetermined amount or more) is determined experimentally in advance as a normal range on the scale 442. During adjustment, the operator adjusts the fixed knob 423 and / or the movable knob 425 while watching the scale 442 so that it falls within the normal range.

[0051] This makes it possible to adjust the radical generator 4 to a favorable state where a sufficient amount of radical species can be generated, although the plasma emission intensity is not necessarily at its maximum. Furthermore, by recording the positions of the fixed knob 423 and / or the movable knob 425 on the scale 442 at the end of the adjustment, it is possible to quickly return the fixed knob 423 and / or the movable knob 425 to a state close to the original state even if the positions of the fixed knob 423 and / or the movable knob 425 are displaced due to device maintenance or the like.

[0052] In the above description, the operator rotates the movable knob 425 itself with his fingers to make the adjustment, but instead of relying on such manual operation, a drive source may be provided to automatically rotate the movable knob 425.

[0053] Furthermore, in the above embodiment, the inner cylinder 421 is provided with the tapered portion 421c, but the same adjustment can be achieved by providing the outer cylinder 424 with a tapered portion.

[0054] In the mass spectrometer of the above embodiment, the matching adjustment of the radical generation unit 4 is performed in the manufacturing process of the device before the radical generation unit 4 is incorporated into the device body, that is, in the radical generation unit 4 alone, and also in the final stage of adjusting the entire device after it has been incorporated into the device body. When the matching adjustment is performed in the radical generation unit 4 alone in this way, it is very advantageous that the display processing unit 46 and the display unit 47 are separate from the device body and that adjustment can be made only in the radical generation unit 4, completely independent of the operation of the device.

[0055] On the other hand, when performing matching adjustment of the radical generation unit 4 at the final stage of adjustment of the entire apparatus, or when checking whether the matching adjustment of the radical generation unit 4 is satisfactory during maintenance work on the apparatus that does not involve disassembly, it may be convenient to be able to check information corresponding to the intensity of light emitted from the plasma on the display unit 7, which is the standard user interface of the apparatus. Figure 6 is an overall configuration diagram of a modified example of the mass spectrometer of the above embodiment.

[0056] The difference between the configuration in Figure 6 and that in Figure 1 is that a detection signal from a photodetector 418 provided in the main body 40 of the radical generation unit 4 is input to the control and processing unit 5, which is equipped with an adjustment display processing unit 51, and this adjustment display processing unit 51 displays, for example, a voltage value reflecting the light intensity on the display unit 7. The adjustment display processing unit 51 can be a functional block realized by executing control and processing software installed on a PC. Of course, a configuration having both the configuration shown in Figure 1 and the configuration shown in Figure 6 may also be used.

[0057] Next, another embodiment of a mass spectrometer and an adjustment method thereof according to the present invention will be described with reference to Fig. 7. Fig. 7 is a diagram showing the overall configuration of the mass spectrometer of this embodiment. The same components as those in the mass spectrometers shown in Figs. 1 and 6 are designated by the same reference numerals, and detailed description thereof will be omitted.

[0058] In this mass spectrometer, the main body 40 of the radical generation unit 4 is not provided with a photodetector 148, a display processing unit 46, or a display unit 47. That is, this mass spectrometer does not have the function of detecting the emission intensity of plasma and displaying the result accordingly. Instead, this mass spectrometer has the function of displaying a result that reflects the state of plasma generation in the radical generation chamber 400 based on the results of measuring a specified sample.

[0059] To realize this function, in this mass spectrometer, the control / processing unit 5 includes, as functional blocks, a radical adjustment control unit 52 and a radical adjustment data processing unit 53. The radical adjustment data processing unit 53 includes, as subordinate functional blocks, a specific mass peak extraction unit 531, an intensity difference calculation unit 532, and a radical adjustment display processing unit 533. These functional blocks can be realized by running control / processing software installed on a PC on the PC.

[0060] For example, as described in Patent Document 2, when a precursor ion having a specific m / z value derived from a phospholipid having an unsaturated bond is irradiated with oxygen radicals, an adduct ion in which an oxygen atom is attached to the precursor ion is generated.

[0061] Specifically, when mass analysis is performed on a sample containing phospholipids with unsaturated bonds without supplying oxygen radicals to the collision cell 132 and a mass spectrum is obtained, only precursor ions (other product ions are ignored for now) are observed, as shown in FIG. 8(A). In contrast, when mass analysis is performed on the same sample with a sufficient supply of oxygen radicals to the collision cell 132 and a mass spectrum is obtained, adduct ions with oxygen atoms attached appear 16 Da away from the precursor ions, as shown in FIG. 8(B). The signal intensity of these adduct ions depends on the amount of oxygen radicals supplied, and therefore indirectly reflects the state of plasma generation. In other words, the signal intensity of the adduct ions has substantially the same meaning as the detection signal from the photodetector 418 in the above-described embodiment. The mass spectrometer of this embodiment utilizes this information to display a monitor for matching adjustment.

[0062] Specifically, a preparation sample containing a phospholipid having an unsaturated bond is prepared, and the sample is continuously supplied to the ESI probe 101. When the operator performs a predetermined operation using the input unit 6, the radical preparation control unit 52 controls each unit so as to alternately perform a product ion scan measurement on precursor ions of a predetermined m / z value in a state in which the supply of radical species to the collision cell 132 is stopped by closing the valve 45 in the radical generation unit 4, and a product ion scan measurement on precursor ions of a predetermined m / z value in a state in which the valve 45 can be opened to supply radical species to the collision cell 132.

[0063] In the radical adjustment data processing unit 53, a specific mass peak extraction unit 531 extracts the signal intensity of a mass peak at the m / z value of the adduct ion, for example, from the obtained mass spectrum data. An intensity difference calculation unit 532 calculates the difference in signal intensity of a mass peak at the m / z value of the adduct ion obtained when the supply of radical species to the collision cell 132 is stopped and when radical species can be supplied to the collision cell 132. A radical adjustment display processing unit 533 displays a numerical value corresponding to the calculated difference in signal intensity on the display unit 7.

[0064] The difference in signal intensity increases as the amount of oxygen radicals supplied to the collision cell 132 increases, and the amount of oxygen radicals increases as the plasma generation state in the radical generation chamber 400 improves. Therefore, the operator performs appropriate matching adjustment by adjusting the fixed knob 423 and the movable knob 425 while watching the value displayed on the display unit 7 so that the value is as large as possible.

[0065] Furthermore, instead of the difference in signal intensity of the mass peak at the m / z value of the adduct ion in which oxygen atoms are attached to the precursor ion, the difference in signal intensity of the mass peak at the m / z value of the original precursor ion (the greater the amount of oxygen radicals, the greater the degree of decrease in signal intensity) may be used.Furthermore, instead of the adduct ion in which oxygen atoms are attached to the precursor ion, the signal intensity of the mass peak at the m / z value of various ions that can be generated by the action of oxygen radicals, such as product ions in which oxygen atoms are attached to ions dissociated by the action of oxygen radicals, may also be used.

[0066] Of course, as the preparation sample, not only phospholipids having unsaturated bonds but also samples containing compounds from which various product ions are characteristically generated by radical species such as oxygen radicals can be used.

[0067] As described above, the mass spectrometer of this embodiment can also accurately perform matching adjustment of the radical generation unit 4, just like the mass spectrometers described above. In particular, by performing adjustment using a numerical display of the intensity signal, adjustment can be performed according to quantitative standards without relying on the subjective judgment of the operator. Furthermore, by recording the voltage value at the end of adjustment, it is possible to easily grasp the deterioration of the radical generation unit 4 that occurs with use of the device and any deviations in adjustment that occur during device maintenance.

[0068] Although the mass spectrometers in the above-described embodiments and modifications are quadrupole time-of-flight mass spectrometers, it is clear that the present invention can also be applied to other types of mass spectrometers, such as triple quadrupole mass spectrometers, which are equipped with a collision cell and an ion trap that use radical species to dissociate ions.

[0069] Furthermore, the above-described embodiment and modified examples are merely examples of the present invention, and it goes without saying that any appropriate modifications, corrections, additions, etc. made within the spirit of the present invention will also be encompassed within the scope of the claims of the present application.

[0070] [Various aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0071] (Item 1) One aspect of the mass spectrometer according to the present invention is a mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation, a radical generation unit including: a radical generation chamber; an antenna for supplying high frequency power to the inside of the radical generation chamber; an impedance adjustment unit for adjusting the impedance of the antenna in response to an operation by an operator; and a raw material gas supply unit for supplying a raw material gas to the inside of the radical generation chamber, the radical generation unit supplying the raw material gas and the high frequency power to the radical generation chamber and generating plasma in the radical generation chamber to generate radical species from the raw material gas; an information providing unit that generates an electric signal that reflects the state of plasma generation inside the radical generation chamber and provides visible or audible information based on the electric signal to an operator; Equipped with.

[0072] (Item 9) One aspect of the method for adjusting a mass spectrometer according to the present invention is a method for adjusting a mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation, comprising: a radical generation step of supplying a source gas to a radical generation chamber and supplying high-frequency power via an antenna to generate plasma inside the radical generation chamber, thereby generating radical species from the source gas; an information providing step of generating an electric signal reflecting the state of plasma generation inside the radical generation chamber and providing visible or audible information based on the electric signal to an operator; an adjusting step of adjusting the impedance of the antenna in response to an operation by an operator in accordance with the provided visual or audible information; It has.

[0073] According to one aspect of the mass spectrometer described in paragraph 1 and the method for adjusting a mass spectrometer described in paragraph 9, matching adjustment for generating radical species in the radical generation unit can be performed simply and accurately, that is, so that a sufficient amount of radical species is generated. This reduces the effort and time required to adjust the radical generation unit, for example, during the manufacturing or adjustment stage of the device or during maintenance of the device, and reduces the costs involved. Furthermore, by accurately adjusting the radical generation unit, a sufficient amount of radical species can be stably supplied, allowing ions derived from a target sample to be dissociated with high efficiency and allowing analytical performance such as detection sensitivity to be fully demonstrated.

[0074] (Item 2) In the mass spectrometer described in item 1, the information providing unit may include at least one of a light detecting unit that measures the intensity of light emitted from the plasma inside the radical generation chamber, and a display unit that displays visible information reflecting the intensity of the light obtained by the light detecting unit, or a sound generating unit that emits audible information reflecting the intensity of the light.

[0075] (Item 10) In the method for adjusting a mass spectrometer according to item 9, Supply The step can include at least one of a light detection step of measuring the intensity of light emitted from the plasma inside the radical generation chamber, and a display step of displaying visible information reflecting the intensity of the light obtained in the light detection step, or a sound generation step of emitting audible information reflecting the intensity of the light.

[0076] In the mass spectrometer described in paragraph 2, the detection signal obtained by the light detection unit can be processed and displayed or audibly output via a control unit that controls the operation of the mass spectrometer as a whole. However, it is also possible to incorporate a simple processing circuit and a display into the radical generation unit itself without using the control unit. In particular, this latter configuration makes it possible to perform matching adjustments on the radical generation unit alone before assembling the device. This makes it possible, for example, to discover defects in the radical generation unit itself early on.

[0077] (Item 3) In the mass spectrometer described in item 2, the display unit may display the voltage value or current value obtained by the light detection unit as a numerical value or a mark based on the numerical value.

[0078] According to the mass spectrometer described in paragraph 3, adjustments can be made based on quantitative standards, thereby reducing differences between devices. Furthermore, it is possible to avoid using a radical generator that does not meet the standards. Furthermore, by recording the values ​​when matching adjustments are made for a certain radical generator, it is possible to check the degree of deterioration associated with use of that radical generator.

[0079] (Item 4) In the mass spectrometer described in item 1, the information providing unit can create the visible or audible information and provide it to an operator based on a detection signal obtained by detecting ions whose quantity changes depending on operations on ions using radical species generated in the radical generating unit.

[0080] (Item 11) In the method for adjusting a mass spectrometer described in Item 9, the information providing step can be to create the visible or audible information and provide it to the operator based on a detection signal obtained by detecting ions whose quantity changes due to operations on ions using radical species generated in the radical generation step.

[0081] In the mass spectrometer described in paragraph 4 and the method for adjusting a mass spectrometer described in paragraph 11, the operator performs matching adjustment while checking the results of an actual analysis of a specified sample. Therefore, although there is a restriction that adjustment can only be performed when the device is assembled, it is possible to appropriately adjust so that a sufficient amount of the target radical species is generated. Furthermore, there is no need to add special hardware such as a light detection unit that detects light emitted from the plasma, and this can basically be achieved by adding only software.

[0082] (Item 5) In the mass spectrometer described in any one of Items 1 to 4, the impedance adjustment unit adjusts the impedance of the antenna by changing the grounding point of the antenna in response to an operator's movement of an operator, and the radical generation unit can further include a position indication unit having a scale along the direction of movement of the operator.

[0083] In the mass spectrometer described in paragraph 5, the operator can know the status of the matching adjustment by the display and sound from the information providing unit, as well as by the indication of the position of the operator by the scale on the position indicator. This allows the operator to quickly understand the deviation and return the operator to the original state even if the position of the operator is unintentionally shifted during maintenance of the device, for example, by recording the position of the operator when the matching adjustment is appropriate. In addition, coarse adjustment can be performed based on the range of the scale on the position indicator.

[0084] (Item 6) In the mass spectrometer according to any one of Items 1 to 4, the radical generating unit a cylindrical tube made of a dielectric material, into which a source gas is introduced and part of which in the longitudinal direction serves as the radical generation chamber; the antenna being a conductor wound around the cylindrical tube; an outer conductor portion having a conductive inner circumferential surface that is coaxial with the cylindrical tube and has a concentric cross section; a connection portion constituting the impedance adjustment portion, which is located in the gap between the inner peripheral surface of the outer conductor portion and the outer peripheral surface of the cylindrical tube, contacting both the inner peripheral surface of the outer conductor portion and the antenna to electrically connect them, and whose electrical connection point is slidable in the longitudinal direction of the outer conductor portion; It can include:

[0085] In the mass spectrometer described in item 6, matching adjustment can be achieved by a simple operation of sliding the connecting portion in the longitudinal direction of the outer conductor portion.

[0086] (Item 7) In the mass spectrometer described in item 6, the connecting portion has a double cylindrical structure including an inner cylinder and an outer cylinder, and the ends of the inner cylinder and the outer cylinder on the same side are divided in the circumferential direction by slits extending in the axial direction to form a plurality of divided pieces, and a tapered portion is formed on the outside of the divided pieces of the inner cylinder, which bulges outward as it approaches the tip side, or on the inside of the divided pieces of the outer cylinder, which bulges inward as it approaches the tip side, The impedance adjustment unit may further include a movement mechanism that moves the outer cylindrical body relative to the inner cylindrical body, or vice versa, the inner cylindrical body relative to the outer cylindrical body, toward their respective tip ends.

[0087] In the mass spectrometer described in paragraph 7, the multiple segments formed on the inner and outer cylinders function as leaf springs, and when the outer cylinder is moved axially relative to the inner cylinder, the leaf springs bring the inner and outer cylinders into close contact with the antenna and the external conductor, respectively. Therefore, according to the mass spectrometer described in paragraph 7, the connection point via the connection part can be fixed at any position in the axial direction of the antenna. At the same time, stable electrical contact between the antenna and the external conductor via the connection part is ensured, ensuring reliable conduction between them. This makes it possible to easily achieve and maintain a state in which matching has been appropriately adjusted. As a result, desired radical species can be stably and efficiently generated in the radical generation chamber.

[0088] (Item 8) In the mass spectrometer according to item 7, the movement mechanism includes an operator operated by an operator, The radical generating section may include a position indicating section having a scale provided along the direction of movement of the operating element accompanying the movement of the outer cylinder body or the inner cylinder body by the movement mechanism.

[0089] According to the mass spectrometer described in item 8, the same effects as those of the mass spectrometer described in item 5 can be achieved.

[0090] (Item 12) Another aspect of the mass spectrometer according to the present invention is a mass spectrometer comprising a radical generation unit that generates radical species, dissociates ions using the radical species, and analyzes the ions generated by the dissociation, wherein the radical generation unit: a radical generation chamber; a source gas supply unit that supplies a source gas that serves as a source of radical species into the radical generation chamber; an antenna for supplying high frequency power to the inside of the radical generation chamber; an impedance adjustment unit that adjusts the impedance of the antenna by changing the ground point of the antenna in response to a movement of an operator; a position indicator having a scale along the direction of movement of the operator; It can include:

[0091] In the mass spectrometer described in paragraph 12, the operator can perform matching adjustment by moving the control using a specific scale position or scale range on the position indicator as a reference. This makes matching adjustment easy. Furthermore, even if the position of the control is unintentionally shifted during maintenance of the device, the operator can quickly determine the shift and return it to its original state.

[0092] (Item 13) In the mass spectrometer according to Item 12, the radical generating unit comprises: a cylindrical tube made of a dielectric material, into which a source gas is introduced and part of which in the longitudinal direction serves as the radical generation chamber; the antenna being a conductor wound around the cylindrical tube; an outer conductor portion having a conductive inner circumferential surface that is coaxial with the cylindrical tube and has a concentric cross section; a connection portion constituting the impedance adjustment portion, which is located in the gap between the inner peripheral surface of the outer conductor portion and the outer peripheral surface of the cylindrical tube, contacting both the inner peripheral surface of the outer conductor portion and the antenna to electrically connect them, and whose electrical connection point is slidable in the longitudinal direction of the outer conductor portion in response to an operator's movement of an operating element; It can include:

[0093] According to the mass spectrometer described in paragraph 13, similar to the mass spectrometer described in paragraph 6, matching adjustment can be achieved by a simple operation of sliding the connecting portion in the longitudinal direction of the outer conductor portion. [Explanation of symbols]

[0094] 1...Vacuum chamber 10...Ionization chamber 101...ESI probe 102...Desolvation 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 133...Multipole ion guide 134...Ion Guide 14…Second analysis room 141...Ion transport electrode 142...Orthogonal acceleration section 143...acceleration electrode 144...Reflecting electrode 145...Ion detector 146...Flight tube 4...Radical generation section 40...Main body 400...Radical generation chamber 410...Central cylindrical tube 411...Spiral antenna 412...Outer conductor part 413, 415...Magnet 414...First casing 416...Microwave supply connector 417...Light source 418...Photodetector 420…Resonator adjustment mechanism 421…Inner cylinder 421a...Notch 421b...Split piece 421c...Tapered section 422...Male thread 423...Fixed knob 424...Outer cylinder 424a...Notch 424b…Split piece 425...movable knob 431...Gap 440...Second casing 441...Opening 442...scale 41, 45...valve 42...Raw material supply section 43...Microwave power supply 44...Transport pipe 46...Display processing unit 47…Display section 5...Control and processing section 51...Adjustment display processing unit 52...Radical adjustment control section 53...Radical adjustment data processing unit 531...Specific mass peak extraction section 532...Intensity difference calculation unit 533...Radical adjustment display processing unit 6...Input section 7...Display section C...Ion optical axis

Claims

1. A mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation, a radical generation unit including: a radical generation chamber; an antenna for supplying high frequency power to the inside of the radical generation chamber; an impedance adjustment unit for adjusting the impedance of the antenna in response to an operation by an operator; and a raw material gas supply unit for supplying a raw material gas to the inside of the radical generation chamber, the radical generation unit supplying the raw material gas and the high frequency power to the radical generation chamber and generating plasma in the radical generation chamber to generate radical species from the raw material gas; an information providing unit that generates an electric signal that reflects the state of plasma generation inside the radical generation chamber and provides visible or audible information based on the electric signal to an operator; A mass spectrometer comprising:

2. The information providing unit a light detection unit that measures the intensity of light emitted from the plasma inside the radical generation chamber; at least one of a display unit that displays visible information reflecting the intensity of the light obtained by the light detection unit and a sound generation unit that generates audible information reflecting the intensity of the light; The mass spectrometer of claim 1 , comprising:

3. 3. The mass spectrometer according to claim 2, wherein the display unit displays the voltage value or current value obtained by the light detection unit as a numerical value or a mark based on the numerical value.

4. The mass spectrometer of claim 1, wherein the information providing unit creates the visible or audible information and provides it to an operator based on a detection signal obtained by detecting ions whose quantity changes depending on operations on ions using radical species generated in the radical generating unit.

5. the impedance adjustment unit adjusts the impedance of the antenna by changing the ground point of the antenna in response to a movement operation of an operator, 5. The mass spectrometer according to claim 1, wherein the radical generating section further comprises a position indicating section having a scale along the direction of movement of the manipulator.

6. The radical generating unit is a cylindrical tube made of a dielectric material, into which a source gas is introduced and part of which in the longitudinal direction serves as the radical generation chamber; the antenna being a conductor wound around the cylindrical tube; an outer conductor portion having a conductive inner circumferential surface that is coaxial with the cylindrical tube and has a concentric cross section; a connection portion constituting the impedance adjustment portion, which is located in the gap between the inner peripheral surface of the outer conductor portion and the outer peripheral surface of the cylindrical tube, contacting both the inner peripheral surface of the outer conductor portion and the antenna to electrically connect them, and whose electrical connection point is slidable in the longitudinal direction of the outer conductor portion; The mass spectrometer according to any one of claims 1 to 4, comprising:

7. The connecting portion has a double cylindrical pipe structure including an inner cylindrical body and an outer cylindrical body, and the ends of the inner cylindrical body and the outer cylindrical body on the same side are divided in the circumferential direction by slits extending in the axial direction to form a plurality of divided pieces, and a tapered portion is formed on the outside of the divided piece of the inner cylindrical body, which bulges outward as it approaches the tip side, or on the inside of the divided piece of the outer cylindrical body, which bulges inward as it approaches the tip side, 7. The mass spectrometer according to claim 6, wherein the impedance adjustment unit further includes a movement mechanism that moves the outer cylinder relative to the inner cylinder, or vice versa, the inner cylinder relative to the outer cylinder, toward their respective tip ends.

8. The mass spectrometer according to claim 7, wherein the moving mechanism includes an operator operated by an operator, and the radical generating unit includes a position indicating unit having a scale provided along the direction of movement of the operator accompanying the movement of the outer cylinder or the inner cylinder by the moving mechanism.

9. A method for adjusting a mass spectrometer that dissociates ions using radical species and analyzes the ions produced by the dissociation, comprising: a radical generation step of supplying a source gas to a radical generation chamber and supplying high-frequency power via an antenna to generate plasma inside the radical generation chamber, thereby generating radical species from the source gas; an information providing step of generating an electric signal reflecting the state of plasma generation inside the radical generation chamber and providing visible or audible information based on the electric signal to an operator; an adjusting step of adjusting the impedance of the antenna in response to an operation by an operator in accordance with the provided visual or audible information; A method for adjusting a mass spectrometer having the above structure.

10. The information providing step includes: a light detection step of measuring the intensity of light emitted from the plasma inside the radical generation chamber; at least one of a display step of displaying visible information reflecting the intensity of the light obtained in the light detection step and a sound generation step of generating audible information reflecting the intensity of the light; The method for adjusting a mass spectrometer according to claim 9 , comprising:

11. The method for adjusting a mass spectrometer according to claim 9, wherein the information providing step creates the visible or audible information and provides it to an operator based on a detection signal obtained by detecting ions whose quantity changes depending on operations on ions using radical species generated in the radical generation step.

12. A mass spectrometer including a radical generating unit that generates radical species, dissociates ions using the radical species, and analyzes the ions generated by the dissociation, wherein the radical generating unit a radical generation chamber; a source gas supply unit that supplies a source gas that serves as a source of radical species into the radical generation chamber; an antenna for supplying high frequency power to the inside of the radical generation chamber; an impedance adjustment unit that adjusts the impedance of the antenna by changing the ground point of the antenna in response to a movement of an operator; a position indicator having a scale along the direction of movement of the operator; A mass spectrometer comprising:

13. The radical generating unit is a cylindrical tube made of a dielectric material, into which a source gas is introduced and part of which in the longitudinal direction serves as the radical generation chamber; the antenna being a conductor wound around the cylindrical tube; an outer conductor portion having a conductive inner circumferential surface that is coaxial with the cylindrical tube and has a concentric cross section; a connection portion constituting the impedance adjustment portion, which is located in the gap between the inner peripheral surface of the outer conductor portion and the outer peripheral surface of the cylindrical tube, contacting both the inner peripheral surface of the outer conductor portion and the antenna to electrically connect them, and whose electrical connection point is slidable in the longitudinal direction of the outer conductor portion in response to an operator's movement of an operating element; The mass spectrometer of claim 12 , comprising:

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