Mass Spectrometer and Mass Spectrometry Method

Abstract

A mass spectrometry method according to the present invention comprises: introducing precursor ions into a reaction chamber (step 2); generating radicals in a radical generating chamber; generating product ions by irradiating the precursor ions with the radicals (step 15); and measuring the masses of the product ions (step 16). When the radicals are generated, raw material gases are introduced into the radical generating chamber (steps 5, 8), high-frequency power is supplied to the raw material gases at the same time that or after the precursor ions are introduced into the reaction chamber (steps 5, 8), and plasma emission is made to occur by supplying electrons to the raw material gases while high-frequency power is supplied, whereby radicals are produced as a result of the plasma emission being radiated on the raw material gases (steps 6, 9).

Description

[Technical field]

[0001] The present invention relates to a mass spectrometer and a mass analysis method. [Background technology]

[0002] Mass spectrometry is widely used to identify polymer compound components in a sample and analyze their structures. In this method, ions with a specific mass-to-charge ratio are selected as precursor ions from ions derived from the sample components, and various product ions are generated by dissociating the precursor ions and separating them according to their mass-to-charge ratios.

[0003] Many polymer compounds are organic substances whose main skeleton is a hydrocarbon chain. To understand the characteristics of such polymer compounds, it is effective to obtain information such as the presence or absence of unsaturated bonds of carbon atoms and characteristic functional groups. Recently, a radical attachment dissociation method has been proposed, in which radicals are attached to precursor ions derived from sample components, causing the precursor ions to dissociate at the positions of unsaturated bonds of carbon atoms or specific functional groups.

[0004] For example, Patent Documents 1 and 2 describe a method of selectively dissociating precursor ions at the position of a peptide bond by irradiating and attaching hydrogen radicals or the like to precursor ions introduced into a reaction chamber, and Patent Documents 3 and 4 describe a method of selectively dissociating precursor ions at the position of an unsaturated bond contained in a hydrocarbon chain by irradiating and attaching oxygen radicals or the like to precursor ions introduced into a reaction chamber.

[0005] The radicals used in the radical attachment dissociation method are generated, for example, by generating inductively coupled plasma in a radical generation chamber into which a raw material gas has been introduced. Patent Document 5 and Non-Patent Document 1 describe a radical supply unit having a configuration in which a spiral antenna is wound around the outer periphery of a tubular body made of a dielectric material such as quartz, a raw material gas is introduced into the inside of the tubular body, high-frequency power is supplied to the antenna, and inductively coupled plasma is generated to generate radicals, and the radicals are transported to a reaction chamber through a transport tube. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 133259 [Patent Document 2] International Publication No. 2018 / 186286 [Patent Document 3] International Publication No. 2019 / 155725 [Patent Document 4] International Publication No. 2020 / 240908 [Patent Document 5] JP 2020-177784 A [Non-patent literature]

[0007] [Non-Patent Document 1] Hidenori Takahashi, Yuji Shimabukuro, Daiki Asakawa, Akihito Korenaga, Masaki Yamada, Shinichi Iwamoto, Motoi Wada, Koichi Tanaka, "Identifying Double Bond Positions in Phospholipids Using Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry Based on Oxygen Attachment Dissociation", Mass Spectrometry, Volume 8, Issue 2, Pages S0080, 2020 [Non-Patent Document 2] Hiroyoshi Kitabayashi, Haruhisa Fujii, "Contact Electrification Characteristics of High-Resistance Insulating Glass", Transactions of the Institute of Electrical Engineers of Japan, Vol. 125, No. 2, 2005 [Non-Patent Document 3] Jijun Ding, Haixia Chen, Haiwei Fu, "Defect-related photoluminescence emission from annealed ZnO films deposited on AlN substrates", Materials Research Bulletin 95 (2017) 185-189 [Non-Patent Document 4] Hiroyoshi Kitabayashi, Haruhisa Fujii, "Contact electrification characteristics between insulators and glass", Journal of the Electrostatic Society of Japan 27, 5, (2003), pp.240-245 Summary of the Invention [Problem to be solved by the invention]

[0008] In the above radical supply section, even if the source gas is supplied at a predetermined flow rate and the high frequency power of a predetermined magnitude is applied, plasma is not always generated at a fixed timing. It is difficult to control the timing of plasma generation, and conventionally, before the start of sample measurement, plasma is generated with the valve installed in the transport tube closed, and the valve is opened to irradiate radicals in accordance with the timing of introducing precursor ions into the reaction chamber. In this way, the source gas is supplied and high frequency power is applied for a period of time longer than the time for actually irradiating the precursor ions with radicals, which causes a problem of high consumption of source gas and electricity.

[0009] An object of the present invention is to provide a technique capable of reducing the consumption of source gas and electricity when generating radicals from a source gas and irradiating precursor ions with the radicals to generate product ions. [Means for solving the problem]

[0010] The mass spectrometry method according to the present invention, which has been made to solve the above problems, comprises: introducing precursor ions into a reaction chamber; generating radicals in a radical generation chamber; generating product ions by irradiating the precursor ions in the reaction chamber with the radicals; measuring the mass of the product ions; A method of mass spectrometry comprising: The step of generating radicals includes: introducing a source gas into the radical generation chamber; In the reaction chamber The above supplying high frequency power to the source gas simultaneously with or after the precursor ions are introduced; generating plasma emission by supplying electrons to the source gas while the high frequency power is being supplied, and irradiating the source gas with the plasma emission to generate the radicals; It is equipped with the following.

[0011] In order to solve the above problems, the mass spectrometer according to the present invention comprises: a reaction chamber into which precursor ions are introduced; A radical generation chamber; a raw material gas supply unit that supplies a raw material gas into the radical generation chamber; a high frequency power supply unit for supplying high frequency power for generating plasma inside the radical generation chamber; an electron supply unit that supplies electrons to the inside of the radical generation chamber; The source gas is supplied to the radical generation chamber, and The above The high frequency power is supplied simultaneously with or after the precursor ions are introduced, and the electron supply unit supplies the high frequency power while the high frequency power is being supplied. Radical Generation Indoors The above a control unit that controls operations of the source gas supply unit, the high frequency power supply unit, and the electron supply unit so as to supply electrons; Equipped with. Effect of the Invention

[0012] The mass spectrometry method and mass spectrometry apparatus according to the present invention are used to irradiate precursor ions introduced into a reaction chamber with radicals and generate product ions from the precursor ions. In the present invention, a source gas is introduced into the radical generation chamber, high-frequency power is supplied, and electrons are further supplied to the source gas in the radical generation chamber to generate plasma emission. When electrons are supplied to the source gas inside the radical generation chamber, plasma emission is instantly generated in response to the electrons. In this way, in the present invention, plasma emission is generated in accordance with the timing at which the precursor ions are introduced into the reaction chamber to generate radicals, so that the consumption of source gas and power can be reduced. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing the configuration of a main part of an embodiment of a mass spectrometer according to the present invention; [Diagram 2] FIG. 2 is a schematic diagram of a radical supply unit in the mass spectrometer of the present embodiment. [Diagram 3] FIG. 2 is a schematic diagram of a radical transport path in the mass spectrometer of the present embodiment. [Figure 4] 1 is a flowchart showing the procedure of one embodiment of a mass spectrometry method according to the present invention. [Diagram 5] 1 shows the results of measuring plasma generation conditions using the mass spectrometer of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a mass spectrometer and a mass spectrometric method according to the present invention will be described with reference to the drawings.

[0015] FIG. 1 is a diagram showing the configuration of the main parts of a liquid chromatograph mass spectrometer 100 in which a mass spectrometer 1 according to the present embodiment is combined with a liquid chromatograph 2. As shown in FIG.

[0016] The liquid chromatograph 2 includes a mobile phase container 20 that contains a mobile phase, a liquid delivery pump 21 that delivers the mobile phase, an injector 22, and a column 23. In addition, an autosampler 24 that introduces a plurality of liquid samples into the injector 22 in a predetermined order is connected to the injector 22.

[0017] The mass spectrometer 1 comprises a main body consisting of an ionization chamber 10, which is at approximately atmospheric pressure, and a vacuum chamber, and a control / processing unit 7. Inside the vacuum chamber, in order from the ionization chamber 10 side, there are a first intermediate vacuum chamber 11, a second intermediate vacuum chamber 12, a third intermediate vacuum chamber 13, and an analysis chamber 14, and the structure has a multi-stage differential pumping system in which the degree of vacuum increases in this order.

[0018] An electrospray ionization probe (ESI probe) 101 that applies an electric charge to a liquid sample and sprays it is installed in the ionization chamber 10. Sample components separated in the column 23 of the liquid chromatograph 2 are sequentially introduced into the ESI probe 101.

[0019] The ionization chamber 10 and the first intermediate vacuum chamber 11 are connected through a thin-diameter heated capillary 102. In the first intermediate vacuum chamber 11, an ion lens 111 is arranged, 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 flight path.

[0020] 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.

[0021] The third intermediate vacuum chamber 13 is provided with a quadrupole mass filter 131 that separates ions according to their mass-to-charge ratio, a collision cell 132 equipped with a multipole ion guide 133 therein, and an ion guide 134 for transporting ions emitted from the collision cell 132. The ion guide 134 is composed of multiple ring-shaped electrodes of the same diameter.

[0022] A collision gas supply unit 4 is connected to the collision cell 132. The collision gas supply unit 4 has a collision gas source 41, a gas introduction flow path 42 that introduces gas from the collision gas source 41 into the collision cell 132, and a valve 43 that opens and closes the gas introduction flow path 42. An inert gas such as nitrogen gas or argon gas is used as the collision gas. Although no collision gas is used in the measurement example described below in which precursor ions are dissociated by a radical attachment reaction, information on product ions having a molecular structure different from that of product ions generated by the radical attachment reaction can be collected by performing a measurement in which compounds contained in the same liquid sample are fragmented by collision-induced dissociation (CID).

[0023] 1 and 2, the radical supply unit 5 includes a radical source 54 having a radical generation chamber 51 formed therein, a vacuum pump (not shown) for evacuating the radical generation chamber 51, a raw material gas supply source 52 for supplying a gas (raw material gas) that is a raw material for radicals, and a high-frequency power supply unit 53. A valve 56 for adjusting the flow rate of the raw material gas is provided in a flow path from the raw material gas supply source 52 to the radical generation chamber 51.

[0024] The radical source 54 has a tubular body 541 made of a dielectric material, and its internal space serves as the radical generation chamber 51. The tubular body 541 is inserted into a hollow cylindrical magnet 544 and fixed in place by a plunger 545. A spiral antenna 542 (indicated by a broken line in FIG. 2) is wound around the outer periphery of a portion of the tubular body 541 that is located inside the magnet 544.

[0025] The radical source 54 is also provided with a high-frequency power input unit 546. High-frequency power is supplied to the high-frequency power input unit 546 from the high-frequency power supply unit 53. The radical source 54 is further provided with a flange 547 for fixing the tip portion of the radical source 54. A hollow cylindrical magnet 548 having the same diameter as the magnet 544 is accommodated inside the flange 547 and pairs with the magnet 544. The magnets 544 and 548 generate a magnetic field inside the tubular body 541 (radical generation chamber 51), and the action of this magnetic field makes it easy to generate and maintain plasma. The high-frequency power supplied from the high-frequency power supply unit 53 may be a general continuous wave or may be pulse width modulated (PWM) controlled. When PWM-controlled high-frequency power is supplied, plasma A PWM signal is sent from the generation control unit 76 (described later) to the high-frequency power supply unit 53, and at the same time, a control signal synchronized with the PWM signal is sent to the light source 61, thereby synchronizing the supply of high-frequency power to the radical generation chamber 51 and the irradiation of light.

[0026] In addition, a light-transmitting window 60 is provided at a position of the radical source 54 facing the radical generation chamber 51. Outside the light-transmitting window 60, a light source 61 that irradiates light of a predetermined wavelength to the tubular body 541 that constitutes the radical generation chamber 51, and a light detection unit 62 that detects the light emitted in the radical generation chamber 51 are arranged. The light detection unit 62 detects light in a wavelength band that includes the wavelength of the light emitted from the plasma. It is preferable to use a light detection unit 62 that has no sensitivity to the light emitted from the light source 61. This makes it possible to detect the light emission of the plasma without being affected by the light emitted from the light source 61.

[0027] A transport pipe 58 for transporting the radicals generated in the radical generation chamber 51 to the collision cell 132 is connected to the outlet end of the radical source 54 via a valve 582. The transport pipe 58 is an insulating pipe, and for example, a quartz glass pipe or a borosilicate glass pipe can be used.

[0028] 3, a portion of the transport tube 58 that is disposed along the wall surface of the collision cell 132 is provided with a plurality of heads 581. Each head 581 is provided with an inclined cone-shaped irradiation port, and radicals are irradiated in a direction intersecting with the central axis (ion optical axis C) of the ion flight direction. This allows the ions flying inside the collision cell 132 to be irradiated with radicals evenly.

[0029] The analysis chamber 14 is equipped with an ion transport electrode 141 for transporting the ions incident from the third intermediate vacuum chamber 13, an orthogonal acceleration electrode 142 consisting of a pair of a push electrode 1421 and a pull electrode 1422 arranged opposite each other across the ion incident optical axis (orthogonal acceleration region), an acceleration electrode 143 for accelerating the ions sent out to the flight space by the orthogonal acceleration electrode 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 defining the outer edge of the flight space. The ion detector 145 is, for example, an electron multiplier or a multichannel plate.

[0030] The control / processing unit 7 controls the operation of each unit, and has the function of storing and analyzing data obtained by the ion detector 145. The control / processing unit 7 includes a memory unit 71 and a timer unit 72. The memory unit 71 stores a compound database 711 and a radical information database 712. The compound database 711 stores information such as measurement conditions for known compounds (retention time, mass-to-charge ratio of precursor ions, radical species irradiated when analyzing the sample) and product ion spectra.

[0031] The radical information database 712 also stores information on the type of source gas used for generating the radicals, the flow rate of the source gas, and the magnitude of the high-frequency power for each radical species. Two types of plasma generation conditions (first plasma generation conditions and second plasma generation conditions) are prepared for the flow rate of the source gas and the magnitude of the high-frequency power, and are stored together with information on a reference time for using them appropriately. The first plasma generation conditions are used when a reference time or more has elapsed since the previous radicals were generated, and when plasma is not ignited under the second plasma generation conditions described below. The second plasma generation conditions are used when the elapsed time since the previous radicals were generated is less than the reference time. Under the second plasma generation conditions, the flow rate of the source gas and / or the magnitude of the high-frequency power are set to a value smaller than that under the first plasma generation conditions. Furthermore, a threshold value of the detection intensity of the light detection unit 62 is stored. This threshold value is used to determine whether or not the plasma is ignited. The threshold value may be a common value for both the first plasma generation conditions and the second plasma generation conditions, or may be a different value for each generation condition. In addition, the storage unit 71 also stores a method file describing the measurement conditions when performing the measurement described below, and information for converting the flight time of ions into the mass-to-charge ratio of ions.

[0032] Some of the radicals generated in the radical generation chamber 51 remain in the radical generation chamber 51 and gradually disappear with the passage of time. When the raw material gas is introduced with radicals remaining in the radical generation chamber 51, the raw material gas molecules are excited by contact with the radicals and become in a state where they are easily radicalized, so that radicals can be generated from the raw material gas even if the flow rate of the raw material gas and / or the high-frequency power is kept low compared to when there are no radicals in the radical generation chamber 51. The above-mentioned reference time corresponds to the time for which radicals can be considered to remain in the radical generation chamber 51. When the time elapsed since the previous radical generation is less than this reference time, the flow rate of the raw material gas and / or the supply amount of the high-frequency power can be reduced to reduce the consumption of the raw material gas and power. The time for which radicals remain in the radical generation chamber 51 and the flow rate of the raw material gas and the magnitude of the high-frequency power required for generating radicals depend on the volume and structure of the radical generation chamber 51, so that the length of the reference time and the specific values ​​of the flow rate of the raw material gas and the magnitude of the high-frequency power under the first plasma generation condition and the second plasma generation condition may be set for each device by performing a preliminary experiment or simulation.

[0033] The control / processing unit 7 further includes, as functional blocks, a measurement condition setting unit 73, a measurement control unit 74, a judgment unit 75, a plasma generation control unit 76, a plasma detection unit 77, and a warning output unit 78. The substance of the control / processing unit 7 is a general personal computer to which an input unit 8 and a display unit 9 are connected, and the above functional blocks are embodied by executing a pre-installed mass analysis program on the processor.

[0034] Next, an analysis procedure using the liquid chromatograph mass spectrometer 100 of this embodiment will be described as an example of the mass analysis method according to the present invention. Fig. 4 is a flow chart showing the analysis procedure. In this example, a target component contained in each of a plurality of liquid samples is measured. It is also assumed that several days have passed since the previous measurement of the liquid sample.

[0035] When the user issues an instruction to start analysis by a predetermined input operation, the measurement condition setting unit 73 displays the compounds recorded in the compound database 711 on the screen of the display unit 9, and allows the user to specify the target compound to be measured. When the user specifies the target compound, the measurement condition setting unit 73 reads out the measurement conditions for that compound from the compound database 711, and creates a batch file for executing continuous measurements of multiple liquid samples.

[0036] After the batch file is created, when the user issues an instruction to start measurement by a predetermined input operation, the measurement control unit 74 measures a plurality of liquid samples in sequence according to the measurement conditions described in the batch file.

[0037] Prior to the measurement, the measurement control unit 74 operates the vacuum pump to evacuate the inside of the radical generation chamber 51 to a predetermined degree of vacuum.

[0038] Next, the measurement control unit 74 introduces, as the first measurement sample, one of the multiple liquid samples previously set in the autosampler 24 by the user that has been set in a predetermined position, into the injector 22 (step 1). The liquid sample is introduced into the column 23 along with the flow of the mobile phase sent from the mobile phase container 20 by the liquid sending pump 21. The components contained in the liquid sample are separated in time by the column 23, and then introduced sequentially into the electrospray ionization probe 101.

[0039] Ions of a target compound generated by the electrospray ionization probe 101 are drawn into the first intermediate vacuum chamber 11 through the heated capillary 102 due to the pressure difference between the ionization chamber 10 and the first intermediate vacuum chamber 11. In the first intermediate vacuum chamber 11, the ions are focused near the ion optical axis C by the ion lens 111.

[0040] The ions focused in the first intermediate vacuum chamber 11 then enter the second intermediate vacuum chamber 12 and are again focused near the ion optical axis C by the ion guide 121 before entering the third intermediate vacuum chamber 13.

[0041] In the third intermediate vacuum chamber 13, precursor ions are selected from the ions generated from the target compound by the quadrupole mass filter 131. The precursor ions that have passed through the quadrupole mass filter 131 are introduced into the collision cell 132 (step 2).

[0042] After the start of the measurement, a predetermined time (e.g., 1 minute) before the target compound flows out of the column 23 (retention time), the judgment unit 75 acquires information on the measurement time by the timer unit 72 (Step 3). At this point, the first liquid sample is being measured, and no information on the measurement time has been acquired (or a sufficiently long time, such as several days, has passed since the radicals were generated in the previous analysis), so the judgment unit 75 judges that the reference time (e.g., 1 hour) has been exceeded (YES in Step 4).

[0043] When the judgment unit 75 judges that a reference time or more has elapsed since the last plasma generation (YES in step 4), the plasma generation control unit 76 transmits a control signal to set the first plasma generation condition to the raw material gas supply source 52 and the high frequency power supply unit 53. In response to this, based on the first plasma generation condition, the raw material gas is introduced from the raw material gas supply source 52 into the radical generation chamber 51, and a high frequency voltage is supplied from the high frequency power supply unit 53 to the spiral antenna 542 (step 8). Next, in a state where high frequency power is supplied to the raw material gas in the radical generation chamber 51, a control signal is also transmitted from the plasma generation control unit 76 to the light source 61, and the light source 61 irradiates light of a predetermined wavelength into the radical generation chamber 51 (step 9). As described above, the high frequency power applied from the high frequency power supply unit 53 to the spiral antenna 542 may be a continuous wave or may be pulse width modulated (PWM) controlled. When PWM-controlled high-frequency power is supplied, the ON / OFF of the light source is also synchronized with the PWM signal, which has the advantage of limiting the ON time of the light source to only the timing required for the required discharge, thereby extending the life of the light source and suppressing the rise in temperature of the light source. Similarly, pulse-width modulated power can be used when supplying high-frequency power based on the second plasma generation condition (described later).

[0044] The wavelength of the light irradiated into the radical generation chamber 51 is determined according to the material constituting the radical generation chamber 51. For example, when a tubular body 541 made of quartz is used, light with a wavelength of 275 nm or less is irradiated. This causes electrons to be emitted from the wall surface of the tubular body 541 constituting the radical generation chamber 51. These electrons induce plasma emission.

[0045] After transmitting the control signal to each of the above-mentioned parts, the plasma generation control unit 76 also transmits a control signal to the light detection unit 62 to detect the light emission of the plasma generated in the radical generation chamber 51. The output signals from the light detection unit 62 are stored in the memory unit 71 in sequence.

[0046] When a control signal is sent from the plasma generation control unit 76 to the light detection unit 62, the plasma detection unit 77 judges whether or not the plasma is turned on based on whether the detection intensity of the light detection unit 62 exceeds a predetermined threshold value stored in the memory unit 71 (step 10). If the plasma detection unit 77 determines that the plasma is not turned on even after a predetermined time (e.g., 5 seconds) has elapsed after the plasma generation control unit 76 sent the control signal to the light detection unit 62, It is determined that If not (the detection intensity of the light detection unit 62 does not reach the threshold value) (NO in step 10), the power supply from the high frequency power supply unit 53, the supply of the raw material gas, and the light irradiation from the light source 61 are all stopped (step 11), and the measurement is terminated. In addition, the warning output unit 78 displays a screen on the display unit 9 notifying the user of the error. Note that the warning output is not limited to a screen display, and may be an audio output, or both a screen display and an audio output.

[0047] When the plasma detector 77 determines that the plasma is turned on (the detection intensity of the light detector 62 reaches the threshold value) (YES in step 10), the measurement is continued. The radicals generated by the supply of the source gas and high frequency power and the light irradiation are introduced into the collision cell 132 through the transport pipe 58 (step 12).

[0048] When a predetermined time (e.g., 1 minute) has elapsed since the retention time of the target compound, the plasma generation control unit 76 stops the supply of the source gas, the input of high-frequency power, and the light irradiation (step 13). This causes the plasma to disappear, and the generation and supply of radicals are stopped. This predetermined time may be determined appropriately in consideration of the length of the retention time of the target compound (the time it takes for the target compound to flow out of the column 23), and may be written in the method file.

[0049] At the same time that the supply of the source gas, the application of the high frequency power, and the light irradiation are stopped, a predetermined signal is also sent to the timer 72, and the elapsed time measured by the timer 72 is reset (step 14).

[0050] In the collision cell 132, the precursor ions are dissociated by a radical attachment reaction to generate product ions (step 15). The product ions generated in the collision cell 132 are focused near the ion optical axis C by the ion guide 134 and then enter the analysis chamber 14.

[0051] The product ions that have entered the analysis chamber 14 are transported to the orthogonal acceleration electrode 142 by the ion transport electrode 141. A voltage is applied to the orthogonal acceleration electrode 142 at a predetermined period, and the flight direction of the ions is deflected in a direction that is approximately orthogonal to the previous direction. The ions whose flight direction has been deflected are accelerated by the acceleration electrode 143 and sent out into the flight space. The ions sent out into the flight space fly along a predetermined flight path defined by the reflectron electrode 144 and the flight tube 146 for a time according to the mass-to-charge ratio of each ion, and are separated from each other and detected by the ion detector 145 (step 16). The ion detector 145 outputs a signal with a magnitude according to the amount of ions incident each time an ion is incident. The output signals from the ion detector 145 are sequentially stored in the memory unit 71. The memory unit 71 stores measurement data based on the flight time of the ions and the detection intensity of the ions.

[0052] When the measurement of the first liquid sample is completed, the measurement control unit 74 checks whether the measurement of all liquid samples is completed (step 17). Since only the first liquid sample has been measured here, it is determined that the measurement of all liquid samples is not completed (NO in step 17), and the process returns to step 1, where the next liquid sample is introduced from the autosampler 24 to the injector 22, and precursor ions are introduced into the collision cell 132 (step 2). Note that, since the measurement of the first liquid sample is the same as that of the first liquid sample except for the radical generation conditions, only the points that are different from the measurement of the first liquid sample will be described.

[0053] After starting the measurement of the second liquid sample, a predetermined time (e.g., 1 minute) before the target compound flows out of the column 23 (retention time), the determination unit 75 again acquires information on the time measured by the timer unit 72 (step 3). Unlike the measurement of the first liquid sample, the time that has passed since the last plasma was generated is short (e.g., about 15 minutes). Therefore, the determination unit 75 determines that the elapsed time is shorter than the reference time (e.g., 1 hour) (NO in step 4).

[0054] When the judgment unit 75 judges that the time is less than the reference time (NO in step 4), the plasma generation control unit 76 introduces the raw material gas from the raw material gas supply source 52 into the radical generation chamber 51 and supplies a high-frequency voltage from the high-frequency power supply unit 53 to the spiral antenna 542 based on the second plasma generation condition (step 5). Next, while high-frequency power is being supplied to the raw material gas in the radical generation chamber 51, the light source 61 irradiates light of a predetermined wavelength into the radical generation chamber 51 (step 6). As a result, electrons are emitted from the wall surface of the tubular body 541 that constitutes the radical generation chamber 51, as in the previous measurement. These electrons induce plasma.

[0055] After transmitting the control signal to each of the above-mentioned parts, the plasma generation control unit 76 also transmits a control signal to the light detection unit 62 to detect the light emission of the plasma generated in the radical generation chamber 51. The output signals from the light detection unit 62 are stored in the memory unit 71 in sequence.

[0056] When a control signal is sent from the plasma generation control unit 76 to the light detection unit 62, the plasma detection unit 77 determines whether or not the plasma is lit based on whether the detection intensity of the light detection unit 62 exceeds a predetermined threshold value stored in the memory unit 71 (step 7).

[0057] After the plasma generation control unit 76 transmits a control signal to the light detection unit 62, the plasma detection unit 77 detects that the plasma is not lit even after a predetermined time (for example, 5 seconds) has elapsed. It is determined that If not (NO in step 7), the plasma generation control unit 76 introduces the raw material gas from the raw material gas supply source 52 into the radical generation chamber 51 based on the first plasma generation condition, and supplies a high-frequency voltage from the high-frequency power supply unit 53 to the spiral antenna 542 (step 8). Next, while high-frequency power is being supplied to the raw material gas in the radical generation chamber 51, the light source 61 irradiates light of a predetermined wavelength into the radical generation chamber 51 (step 9). This light irradiation may be continued from the light irradiation in the previous step 6. This light irradiation causes electrons to be emitted from the wall surface of the tubular body 541 constituting the radical generation chamber 51, as in the previous measurement, and plasma is induced again.

[0058] Thereafter, the plasma detection unit 77 again determines whether or not the plasma is turned on based on whether the detection intensity of the light detection unit 62 exceeds a predetermined threshold value stored in the memory unit 71 (step 10). If the plasma detection unit 77 determines that the plasma is turned on even after a predetermined time (e.g., 5 seconds) has elapsed since the plasma generation control unit 76 sent a control signal to the light detection unit 62, It is not judged that If not (NO in step 10), the plasma generation control unit 76 stops the power supply from the high frequency power supply unit 53, the supply of the raw material gas, and the light irradiation from the light source 61 (step 11), and ends the measurement. Also, the warning output unit 78 displays a screen on the display unit 9 notifying the error.

[0059] When the plasma detection unit 77 determines that the plasma is turned on (YES in step 7 or YES in step 10), the measurement continues. The radicals generated by the supply of the source gas and high-frequency power and the light irradiation are introduced into the collision cell 132 through the transport pipe 58 (step 12).

[0060] When a predetermined time (e.g., 1 minute) has elapsed since the retention time of the target compound, the plasma generation control unit 76 stops the supply of the source gas, the input of high-frequency power, and the light irradiation. This causes the plasma to disappear, and the generation and supply of radicals are stopped (step 13). This predetermined time may be appropriately determined in consideration of the length of the retention time of the target compound (the time it takes for the target compound to flow out of the column 23) and recorded in the method file. Basically, the above-mentioned predetermined time when the first plasma generation conditions are used may be the same as the above-mentioned predetermined time when the second plasma conditions are used.

[0061] At the same time that the supply of the source gas, the application of the high frequency power, and the light irradiation are stopped, a predetermined signal is also sent to the timer 72, and the elapsed time measured by the timer 72 is reset (step 14).

[0062] Inside the collision cell 132, product ions are generated from the precursor ions by irradiation with radicals (step 15). The product ions are detected after mass separation as described above (step 16). The liquid samples are measured sequentially in the manner described above, and when the measurements of all the liquid samples are completed (YES in step 17), the series of measurements is terminated.

[0063] In conventional mass spectrometers, plasma is generated only by supplying raw material gas and applying high-frequency power, and plasma is not always generated at a fixed timing. Therefore, it is necessary to generate radicals in the radical supply unit 5 before starting measurement. This causes a problem of large consumption of raw material gas and high-frequency power.

[0064] In contrast, in the mass spectrometer of this embodiment, light of a predetermined wavelength is irradiated from the light source 61 onto the tubular body 541, causing electrons to be emitted into the radical generation chamber 51. When raw material gas is supplied and high-frequency power is applied, plasma emission is induced by the electrons, and radicals are instantly generated from the raw material gas irradiated with the plasma emission. Therefore, it is sufficient to generate plasma just before the retention time of the target compound, and the amount of raw material gas and high-frequency power used can be reduced. Furthermore, compared to the conventional configuration in which light irradiation is not performed, plasma can be generated at a desired timing to generate radicals more reliably.

[0065] Furthermore, in the mass spectrometer of this embodiment, when the time elapsed since the last plasma generation is less than a reference time, the amount of source gas supplied and / or the amount of high frequency power input is reduced to generate plasma, which also reduces the amount of source gas and high frequency power used.

[0066] Not all gas molecules contained in the source gas supplied to the radical generation chamber 51 are converted into radicals, and many neutral molecules remain. If the remaining neutral molecules flow into the collision cell 132, this will cause a decrease in the degree of vacuum in the collision cell 132 and the third intermediate vacuum chamber 13. In this embodiment, it is only necessary to supply a minimum amount of source gas at the required timing, so that a decrease in the degree of vacuum in the collision cell 132 and the third intermediate vacuum chamber 13 can be suppressed.

[0067] As a method for supplying electrons to the plasma generation space, for example, it is possible to configure the plasma generation space so that electrons are emitted from a filament. However, if a foreign object such as a filament is placed in the plasma generation chamber when generating radicals as in this embodiment, there is a possibility that undesired substances will be generated or the plasma generation chamber will be contaminated, causing an unexpected chemical reaction with the precursor ions. In contrast, in the above embodiment, electrons are emitted from the material itself that constitutes the radical generation chamber 51, so the above-mentioned concerns do not arise.

[0068] Next, the results of an experiment in which the effects of the present invention were confirmed and the reference time, the first plasma generation condition, and the second plasma generation condition in the above embodiment were investigated will be described.

[0069] In this experiment, oxygen radicals were generated three times by generating inductively coupled plasma using water vapor as a raw material gas under three different light irradiation conditions. Specifically, the light irradiation conditions were no light irradiation (comparative example), light irradiation with a wavelength of 275 nm (Example 1), and light irradiation with a wavelength of 250 nm (Example 2). The wavelength of the light irradiated in Examples 1 and 2 was determined by referring to the upper limit (255 nm) of the wavelength of light capable of releasing electrons by the photoelectric effect, which is determined by the work function (4.85 eV, see Non-Patent Document 2) of quartz, which is the material constituting the radical generation chamber, and the light was irradiated from an LED light source that emits light in a wavelength band centered on the above wavelength. In addition, the generation of plasma was confirmed by the emission of plasma (lighting of visible light). The first plasma generation was performed at least two hours after the end of the previous plasma generation (turning off the plasma), and the second and third radical generation were each performed one hour after the previous plasma was turned off.

[0070] The magnitude of energy required to extract one electron from a target substance to infinity is called the work function. The work functions of various substances are directly measured using ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy, etc., or indirectly measured by contact potential difference method. For example, Non-Patent Document 4 reports that the work function of gold is about 5.1 eV and the work function of nickel is about 4.6 eV, based on measurements using Auger electron spectroscopy. In addition, Non-Patent Document 2 reports that when glass (SiO2) and gold are brought into contact, the glass (SiO2) is positively contact-charged, and when nickel and glass are brought into contact, the glass is negatively contact-charged. In other words, the work function of glass (SiO2) is the work function of gold and the work function of nickel. Work function Therefore, electrons can be extracted by irradiating glass (SiO2) with light in a wavelength band that includes the wavelength between the wavelength corresponding to the work function of gold (243 nm) and the wavelength corresponding to the work function of nickel (269 nm).

[0071] In each measurement, microwaves with a frequency of 2459 MHz were supplied to the antenna from the microwave power source at an output of 23 W, and the flow rate of water vapor was gradually increased from 0 to measure the flow rate at which plasma was ignited (i.e., the minimum flow rate of water vapor required to ignite plasma by supplying the microwaves mentioned above). Specifically, the flow rate was first set to 0 sccm (Standard Cubic Centimeter per Minute) using a mass flow controller (MFC), and if plasma was not ignited after waiting for 3 seconds, the flow rate was increased, and if plasma was not ignited after waiting for another 3 seconds, the flow rate was increased further. In this manner, the flow rate was gradually changed to determine the flow rate at which plasma was ignited. In addition, if plasma was not ignited even when the flow rate was increased to the maximum (2.0 sccm), there was no data for that measurement (plasma was not ignited).

[0072] The measurement results are shown in Figure 5. In the first measurement of the comparative example, plasma did not light up even when the water vapor flow rate was set to the maximum (MFC value of 2.0 sccm), so the plasma was lit once by irradiating it with light of a wavelength of 275 nm, and then the second and subsequent measurements were performed. In the second and third measurements of the comparative example, plasma was lit up when the flow rate was increased to 0.5 sccm and 0.32 sccm, respectively.

[0073] In both Examples 1 and 2, plasma was lit from the first time. In Example 1, the flow rates of water vapor at the first, second, and third plasma lighting times were 0.24 sccm, 0.1 sccm, and 0.2 sccm, respectively. 2 The flow rates of water vapor during the first, second, and third plasma lighting were 0.32 sccm, 0.1 sccm, and 0.2 sccm, respectively.

[0074] In both Examples 1 and 2, plasma was lit when a lower flow rate of water vapor was supplied compared to the comparative example, and it can be seen that the lighting of plasma was induced by light irradiation. In both Examples 1 and 2, plasma was lit when a lower flow rate of water vapor was supplied in the second and third times compared to the flow rate of water vapor when plasma was lit the first time. From this result, it can be said that plasma can be lit even if the flow rate of water vapor is suppressed until a certain time has passed after the previous plasma was lit. This is considered to be due to the fact that a chemically unstable substance generated at the time of the first plasma lighting remained in the radical generation chamber, which induced plasma. Therefore, it is possible to suppress not only the flow rate of the raw material gas as was done in this experiment, but also the power consumption.

[0075] The wavelength of the light irradiated in the above embodiment was set on the premise that electrons would be emitted from quartz, but when a different dielectric material (e.g., aluminum oxide, aluminum nitride) is used to construct the radical generation chamber, the wavelength can be determined by referring to the upper limit of the wavelength of light that can emit electrons by the photoelectric effect, which is determined by the work function of the material, in the same manner as above. For example, since the work function of aluminum oxide is 4.7 eV, light having a central wavelength of about 264 nm should be irradiated. Furthermore, since the work function of aluminum nitride is 3.29 eV (see Non-Patent Document 3), light having a central wavelength of about 376 nm should be irradiated.

[0076] All of the values ​​obtained in the above experiments depend on the configuration of the equipment used in the experiments (e.g., the volume of the radical generation chamber), but by conducting preliminary experiments, it is possible to determine the reference time and flow rate of the raw material gas (first plasma generation condition and second plasma generation condition) in a similar manner for equipment of any configuration.

[0077] The above embodiment and experimental results are merely examples, and may be modified as appropriate in accordance with the spirit of the present invention. Although the above embodiment uses a liquid chromatograph mass spectrometer, a gas chromatograph mass spectrometer may be used, or a mass spectrometer alone may be used without using a chromatograph. Although the above embodiment uses a quadrupole-orthogonal acceleration time-of-flight mass spectrometer, a triple quadrupole mass spectrometer, an ion trap mass spectrometer, or the like may be used.

[0078] In the above experiment, oxygen radicals were generated from water vapor, but oxygen radicals can be generated similarly by using oxygen gas or ozone gas as a raw material gas. In addition to oxygen radicals, for example, hydrogen radicals, hydroxyl radicals, nitrogen radicals, methyl radicals, chlorine radicals, fluorine radicals, phosphate radicals, silicon radicals, etc. may be generated and irradiated to the precursor ions. As a raw material gas capable of generating such radicals, for example, hydrogen gas capable of generating hydrogen radicals, water vapor capable of generating hydrogen radicals, oxygen radicals, and hydroxyl radicals, nitrogen gas capable of generating nitrogen radicals, methyl gas capable of generating methyl radicals, chlorine gas capable of generating chlorine radicals, fluorine gas capable of generating fluorine radicals, phosphoric acid vapor capable of generating phosphate radicals, or silane gas capable of generating silicon radicals can be used. The reference time, the first plasma generation conditions, and the second plasma generation conditions when using each raw material gas may be determined in advance by performing a preliminary experiment, etc.

[0079] In the above embodiment, a predetermined signal is sent to the timer 72 at the same time as the supply of the source gas and high frequency power is stopped, and the elapsed time measured by the timer 72 is reset, but the timer 72 may be configured to reset the elapsed time measured by the timer 72 when the plasma detector 77 detects that the plasma is turned off based on the detection intensity of the light detector 62 falling below a threshold. Either configuration can be used when the plasma lighting time is constant for each measurement. On the other hand, when the plasma lighting time varies for each measurement, it is preferable to use the latter configuration (a configuration in which the elapsed time is reset when the plasma is turned off).

[0080] In the above embodiment, the measurement is terminated if the plasma is not ignited even under the first plasma generation conditions, but a third plasma generation condition in which at least one of the flow rate of the raw material gas and / or the magnitude of the high frequency power is greater than that under the first plasma generation conditions may be preset, and if the plasma is not ignited under the first plasma generation conditions, the third plasma generation condition may be used to ignite the plasma. Alternatively, if the plasma is not ignited under the first plasma generation conditions, the user may be prompted to change at least one of the flow rate of the raw material gas and / or the magnitude of the high frequency power.

[0081] [Aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0082] (Section 1) A mass spectrometry method according to one embodiment includes the steps of: introducing precursor ions into a reaction chamber; generating radicals in a radical generation chamber; generating product ions by irradiating the precursor ions in the reaction chamber with the radicals; measuring the mass of the product ions; A method of mass spectrometry comprising: The step of generating radicals includes: introducing a source gas into the radical generation chamber; In the reaction chamber The above supplying high frequency power to the source gas simultaneously with or after the precursor ions are introduced; generating plasma emission by supplying electrons to the source gas while the high frequency power is being supplied, and irradiating the source gas with the plasma emission to generate the radicals; It is equipped with the following.

[0083] (Section 4) A mass spectrometer according to one embodiment comprises: a reaction chamber into which precursor ions are introduced; A radical generation chamber; a raw material gas supply unit that supplies a raw material gas into the radical generation chamber; a high frequency power supply unit for supplying high frequency power for generating plasma inside the radical generation chamber; an electron supply unit that supplies electrons to the inside of the radical generation chamber; The source gas is supplied to the radical generation chamber, and The above The high frequency power is supplied simultaneously with or after the precursor ions are introduced, and the electron supply unit supplies the high frequency power while the high frequency power is being supplied. Radical Generation Indoors The above a control unit that controls operations of the source gas supply unit, the high frequency power supply unit, and the electron supply unit so as to supply electrons; Equipped with.

[0084] The mass spectrometry method of paragraph 1 and the mass spectrometry apparatus of paragraph 4 are used to irradiate precursor ions introduced into a reaction chamber with radicals to generate product ions from the precursor ions. In the mass spectrometry method of paragraph 1 and the mass spectrometry apparatus of paragraph 4, a raw material gas is supplied into a radical generation chamber, and while high-frequency power is supplied to the raw material gas in the radical generation chamber, electrons are further supplied to generate plasma emission in the radical generation chamber. When electrons are supplied to the raw material gas inside the radical generation chamber, plasma is generated by induction of the electrons. In the mass spectrometry method of paragraph 1 and the mass spectrometry apparatus of paragraph 4, plasma emission is generated in accordance with the timing at which precursor ions are introduced into the reaction chamber to generate radicals, so that the consumption of raw material gas and power can be reduced. In addition, the timing at which plasma is generated from the raw material gas can be controlled by irradiating the inside of the radical generation chamber with light of the above-mentioned predetermined wavelength at the timing at which plasma is desired to be generated. In addition, the above-mentioned "supplying high-frequency power to the raw material gas simultaneously with or after the precursor ions are introduced into the reaction chamber" means that high-frequency power is supplied to the raw material gas simultaneously with or after the precursor ions are introduced into the reaction chamber, and does not exclude the case where high-frequency power is continuously supplied for a predetermined time before the introduction of the precursor ions (e.g., the retention time of the target compound contained in the sample).

[0085] (Section 2) 2. The mass spectrometry method according to claim 1, After a predetermined time has elapsed since the start of the generation of the radicals, the supply of at least one of the source gas and the high frequency power is stopped.

[0086] In the mass spectrometry method of the second paragraph, the source gas and / or the high-frequency power is supplied only during the time period when the radical irradiation is required, so that the consumption of at least one of the source gas and the high-frequency power can be reduced.

[0087] (Section 3) In the mass spectrometry method according to claim 1 or 2, The electrons are Room They are produced by irradiating the constituent materials with light of a wavelength that produces the electrons.

[0088] (Section 8) 8. The mass spectrometer according to any one of claims 4 to 7, The electron supply unit is a light irradiating unit that irradiates light having a wavelength that is predetermined according to the material that constitutes the radical generation chamber.

[0089] When generating plasma, a tubular body made of, for example, quartz is used, and its inside is used as a radical generation chamber. In the mass spectrometry method of paragraph 3 and the mass spectrometry apparatus of paragraph 8, electrons are emitted by irradiating the material (for example, quartz) constituting the inner wall of the radical generation chamber with deep ultraviolet light. The electrons can also be emitted from a filament into the plasma generation space, for example. However, if a foreign object such as a filament is placed in the plasma generation chamber, undesired substances may be generated or the plasma generation chamber may be contaminated, which may cause an unexpected chemical reaction with the precursor ions. In the mass spectrometry method of paragraph 3 and the mass spectrometry apparatus of paragraph 8, electrons are emitted from the material itself constituting the radical generation chamber, so that the above-mentioned concerns do not arise.

[0090] (Section 5) 5. The mass spectrometer according to claim 4, further comprising: A storage unit storing information on a first plasma generating condition including a flow rate of a raw material gas and a magnitude of a high frequency power, a second plasma generating condition in which at least one of the flow rate of the raw material gas and the magnitude of the high frequency power is smaller than that of the first plasma generating condition, and a reference time; a timer that measures the time that has elapsed since plasma was last generated in the radical generation chamber; a plasma generation control unit that generates plasma under the first plasma generation condition when the elapsed time is equal to or greater than a predetermined reference time, and generates plasma under the second plasma generation condition when the elapsed time is less than the reference time; Equipped with.

[0091] When plasma is generated in the radical generation chamber, various substances are generated in a chemical state, and if the time that has elapsed since the plasma was generated is short, plasma can also be easily induced from these substances. In the mass spectrometer of Section 5, by performing a preliminary measurement or the like to estimate the remaining time of these substances and the conditions under which plasma can be generated when these substances are present, it is possible to reduce the consumption of source gas and power consumption when generating plasma when the time that has elapsed since the last plasma was generated is less than the reference time.

[0092] (Section 6) The mass spectrometer according to claim 4 or 5, further comprising: A light detection unit is provided that detects light emitted from the plasma in the radical generation chamber.

[0093] If plasma is not generated during measurement and radicals are not produced, radical attachment reactions do not occur with precursor ions and correct results cannot be obtained. In the mass spectrometer described in paragraph 6, a warning is output when plasma is not generated, allowing the user to easily know that an abnormality has occurred in the measurement.

[0094] (Section 7) 7. The mass spectrometer according to claim 6, further comprising: a plasma detection unit that detects the generation of plasma based on the detection intensity of the light detection unit exceeding a predetermined threshold; a warning output unit that outputs a warning when no plasma generation is detected even after a predetermined time has elapsed since electrons were supplied to the radical generation chamber; Equipped with.

[0095] In the mass spectrometer of paragraph 7, when plasma is not detected, a warning is output by the warning output unit, allowing the user to easily grasp a situation in which plasma is not being generated.

[0096] (Section 9) 8. The mass spectrometer according to claim 6 or 7, the electron supply unit is a light irradiating unit that irradiates light having a wavelength that is predetermined according to a material that constitutes the radical generation chamber, The light detection unit detects light in a wavelength band that does not include the predetermined wavelength.

[0097] The mass spectrometer of paragraph 9 can detect only the light emitted from the plasma without being affected by the light irradiated from the light irradiating part to the radical generation chamber.

[0098] (Section 10) 10. The mass spectrometer according to claim 8 or 9, The material is quartz and the predetermined wavelength is less than or equal to 275 nm.

[0099] In the mass spectrometer of paragraph 10, inexpensive and easily available quartz is used as the material constituting the radical generation chamber when generating inductively coupled plasma, and electrons are emitted from the quartz by irradiating it with light having a wavelength of 275 nm or less, thereby inducing plasma. Note that if the light irradiated from the light irradiating unit is not monochromatic light, the central wavelength of the light irradiated may be 275 nm.

[0100] (Section 11) 11. The mass spectrometer according to any one of claims 8 to 10, The light irradiation unit has an LED light source that emits light of the predetermined wavelength.

[0101] In the mass spectrometer of item 11, narrow-band light can be irradiated to the radical production chamber with stable intensity.

[0102] (Section 12) Section 4 Any of the following items In the mass spectrometer according to the present invention, The radicals generated from the source gas are any one of hydrogen radicals, oxygen radicals, hydroxyl radicals, nitrogen radicals, methyl radicals, chlorine radicals, fluorine radicals, phosphate radicals, and silicon radicals.

[0103] Like the mass spectrometer in item 12, item 4 Any of the following items The radicals irradiated to the precursor ions in the mass spectrometer may be any of hydrogen radicals, oxygen radicals, hydroxyl radicals, nitrogen radicals, methyl radicals, chlorine radicals, fluorine radicals, phosphate radicals, and silicon radicals. Any of these radicals can be generated from a source gas that is easily available. [Explanation of symbols]

[0104] 100...Liquid chromatograph mass spectrometer 1...Mass spectrometer 10…Ionization chamber 101...Electrospray ionization (ESI) probe 11…First intermediate vacuum chamber 12...Second intermediate vacuum chamber 13…Third intermediate vacuum chamber 131...Quadrupole mass filter 132…Collision cell 133...Multipole ion guide 14…Analysis room 142...Orthogonal acceleration electrode 144...Reflectron electrode 145…Ion detector 146…Flight tube 2. Liquid chromatograph 20…Mobile phase container 21...Liquid delivery pump 22...Injector 23…Column 24…Autosampler 4...Collision gas supply section 41... Collision gas source 42...Gas introduction channel 5... Radical supply section 51...Radical generation chamber 52…Source gas supply source 53...High frequency power supply unit 54...Radical source 541...Tubular body 542…Spiral antenna 544, 548...Magnet 546…High frequency power input section 58...transport pipe 581…Head 582…Valve 60...Light-transmitting window 61...Light source 62...Light detection unit 7…Control and processing section 71...Storage section 711...Compound database 712...Radical information database 72...Timekeeping section 73...Measurement condition setting section 74...Measurement control section 75…Judgment section 76...Plasma generation control unit 77...Plasma detector 78...Warning output section 8...Input section 9…Display section C…Ion optical axis

Claims

1. introducing precursor ions into a reaction chamber; generating radicals in a radical generation chamber; generating product ions by irradiating the precursor ions in the reaction chamber with the radicals; measuring the mass of the product ions; A method of mass spectrometry comprising: The step of generating radicals includes: introducing a source gas into the radical generation chamber; supplying high frequency power to the source gas simultaneously with or after the precursor ions are introduced into the reaction chamber; a step of inducing plasma emission by supplying electrons to the raw material gas from an electron supply unit that supplies electrons to the inside of the radical generation chamber while the high-frequency power is being supplied, thereby generating the radicals from the raw material gas; A mass spectrometry method comprising:

2. 2. The mass spectrometry method according to claim 1, wherein the supply of at least one of the source gas and the high frequency power is stopped after a predetermined time has elapsed since the start of the generation of the radicals.

3. The mass spectrometry method according to claim 1 , wherein the electron supply unit generates the electrons by irradiating a material constituting the radical generation chamber with light having a wavelength that generates the electrons.

4. a reaction chamber into which precursor ions are introduced; A radical generation chamber; a raw material gas supply unit that supplies a raw material gas into the radical generation chamber; a high frequency power supply unit for supplying high frequency power for generating plasma inside the radical generation chamber; an electron supply unit that supplies electrons to the inside of the radical generation chamber; a control unit that controls operations of the raw material gas supply unit, the high frequency power supply unit, and the electron supply unit so as to supply the raw material gas to the radical generation chamber, supply the high frequency power simultaneously with or after the precursor ions are introduced into the reaction chamber, and supply the electrons from the electron supply unit into the radical generation chamber in a state in which the high frequency power is being supplied; A mass spectrometer comprising:

5. a storage unit storing information on a first plasma generating condition including a flow rate of a raw material gas and a magnitude of a high frequency power, a second plasma generating condition in which at least one of the flow rate of the raw material gas and the magnitude of the high frequency power is smaller than that of the first plasma generating condition, and a reference time; a timer that measures the time that has elapsed since plasma was last generated in the radical generation chamber; a plasma generation control unit that generates plasma under the first plasma generation condition when the elapsed time is equal to or greater than a predetermined reference time, and generates plasma under the second plasma generation condition when the elapsed time is less than the reference time; The mass spectrometer of claim 4 .

6. moreover, A light detection unit that detects light emitted from the plasma in the radical generation chamber. The mass spectrometer of claim 4 .

7. moreover, a plasma detection unit that detects the generation of plasma based on the detection intensity of the light detection unit exceeding a predetermined threshold; a warning output unit that outputs a warning when no plasma generation is detected even after a predetermined time has elapsed since electrons were supplied to the radical generation chamber; The mass spectrometer of claim 6 , comprising:

8. 5. The mass spectrometer according to claim 4, wherein the electron supply unit is a light irradiation unit that irradiates the radical production chamber with light having a wavelength that is predetermined according to a material that constitutes the radical production chamber.

9. the electron supply unit is a light irradiating unit that irradiates light having a wavelength that is predetermined according to a material that constitutes the radical generation chamber, The mass spectrometer according to claim 6 , wherein the light detection section detects light in a wavelength band that does not include the predetermined wavelength.

10. 9. The mass spectrometer of claim 8, wherein said material is quartz and said predetermined wavelength is less than or equal to 275 nm.

11. The mass spectrometer according to claim 8 , wherein the light irradiating unit has an LED light source that emits light of the predetermined wavelength.

12. 5. The mass spectrometer according to claim 4, wherein the radicals generated from the source gas are any one of hydrogen radicals, oxygen radicals, hydroxyl radicals, nitrogen radicals, methyl radicals, chlorine radicals, fluorine radicals, phosphate radicals, and silicon radicals.

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