JP7323467B2 - Mass spectrometry system and bake-out method - Google Patents

Description

The present invention relates to mass spectrometry systems and bake-out methods, and more particularly to bake-out of emitters in ion sources.

A mass spectrometry system is composed of, for example, a gas chromatograph and a mass spectrometer. In a gas chromatograph, a sample to be measured as a mixture is temporally separated into multiple components, ie multiple compounds. Those compounds are sequentially sent to the mass spectrometer, and mass spectrometry is performed for each compound. This gives a mass spectrum for each compound and also creates a gas chromatogram representing a series of compounds.

A mass spectrometer generally has an ion source and a mass spectrometer. An ion source ionizes a sample introduced therein. As such an ion source, an ion source that follows the Field Ionization (FI) method is known. In the ion source according to the FI method, a high voltage is applied between an emitter functioning as an anode and an electrode functioning as a cathode. The high voltage creates a strong electric field near the emitter. The sample is ionized by the electric field. The FI method is soft ionization in which fragmentation is less likely to occur.

In the ion source according to the FI method, samples and impurities adhere to the emitter surface (specifically, the emitter wire surface). Such deposition weakens the electric field near the emitter, causing a reduction in the amount of ions produced. Therefore, a current is passed through the emitter to heat the emitter, thereby volatilizing the substance adhering to the emitter, that is, detaching the substance adhering to the emitter. Such cleaning is called flashing.

Patent Literature 1 discloses a technique of intermittently passing a current to an emitter in an ion source that conforms to the FI method, that is, a technique of performing intermittent burnout. Japanese Patent Laid-Open No. 2002-200001 does not disclose a bake-out control synchronized with the extraction of a plurality of ion pulses.

JP 2015-68678 A

In a mass spectrometry system, integration periods are generally intermittently set. A plurality of mass spectral signals are integrated in each integration period to generate an integrated mass spectral signal. A blank period is provided after each integration period, and the integrated mass spectrum is transferred to the information processing section in each blank period. It is also possible to use such a blank period to bake out the emitter. However, if all contamination generated on the emitter during the integration period is removed by printing out during the blank period immediately after the integration period, the blank period must be set long. It can be pointed out that the same problem as described above may also occur in other types of ion sources other than the ion source according to the FI method.

An object of the present disclosure is to provide bakeout control that can increase the time efficiency of a mass spectrometry system. Alternatively, an object of the present disclosure is to prevent the degree of contamination of the emitter from changing significantly within each integration period.

A mass spectrometry system according to the present disclosure includes an ion source that includes an emitter and generates an ion flow, a pulse generator that cuts out a plurality of ion pulses from the ion flow, and a plurality of masses by performing mass analysis on the plurality of ion pulses. In the ion source, comprising: a mass spectrometer that generates a spectrum signal; an emitter current supply circuit that supplies an emitter current for burn-out to the emitter; and a controller that controls operation of the emitter current supply circuit a plurality of effective periods that contribute to the generation of the plurality of ion pulses and a plurality of ineffective periods that do not contribute to the generation of the plurality of ion pulses occur alternately; It is characterized by controlling the operation of the emitter current supply circuit so that the emitter current is supplied to the emitter during all or part of the period.

The method for burning out according to the present disclosure comprises the steps of: burning out the emitter by supplying an emitter current to an emitter provided in an ion source during a burning out period; and burning out the emitter during a cooling period after the burning out period. a plurality of pulses of ions are generated from an ion stream generated in the ion source, wherein the ion source comprises a plurality of effective periods contributing to the generation of the plurality of pulses of ions; and a plurality of invalid periods that do not contribute to the generation of ion pulses are alternately set, and the bake-out period and the cooling period are set within at least one invalid period of the plurality of invalid periods. It is characterized.

According to the present disclosure, bakeout control can be achieved that can increase the time efficiency of the mass spectrometry system. Alternatively, according to the present disclosure, it is possible to prevent the degree of contamination of the emitter from changing significantly in each integration period.

1 is a block diagram showing a mass spectrometry system according to an embodiment; FIG. 7 is a timing chart showing operations according to a comparative example; 4 is a timing chart showing operations according to the embodiment; 4 is a timing chart showing details of operations according to the embodiment; FIG. 4 is an explanatory diagram showing a first embodiment of print-out number control; 4 is a flow chart showing the operation of the first embodiment; FIG. 11 is an explanatory diagram showing a second embodiment of the number-of-printing-out control; 9 is a flow chart showing the operation of the second embodiment;

Hereinafter, embodiments will be described based on the drawings.

(1) Outline of Embodiment A mass spectrometry system according to an embodiment includes an ion source, a pulse generator, a mass spectrometer, an emitter current supply circuit, and a controller. The ion source has an emitter and produces a stream of ions. A pulse generator cuts out a plurality of ion pulses from the ion stream. A mass spectrometer generates a plurality of mass spectral signals by mass analyzing a plurality of ion pulses. An emitter current supply circuit supplies an emitter current for burn-out to the emitter. The control section controls the operation of the emitter current supply circuit. In the ion source, a plurality of effective periods that contribute to the generation of the plurality of ion pulses and a plurality of ineffective periods that do not contribute to the generation of the plurality of ion pulses alternately occur. The controller controls the operation of the emitter current supply circuit so that the emitter current is supplied to the emitter during all or part of the plurality of invalid periods.

As a result, the ion flow has a plurality of cutout portions (plurality of effective portions) that are cut out as a plurality of ion pulses, and a plurality of non-cutout portions (plurality of ineffective portions) that remain without being cut out. Each non-sliced portion is a portion that is discarded without forming an ion pulse. In the ion source, each valid period is the period that produces each segmented portion, and each invalid period is the period that produces each non-snipped portion. In general, bakeout during the dead period has no effect on the ion pulse. The above configuration makes use of the unavoidably occurring invalid period and uses the invalid period to burn out or clean the emitter. By utilizing the dead period for bakeout, the efficiency of operation of the mass spectrometry system can be increased.

The ion source is an ion source that requires bake-out, for example, an ion source that conforms to the FI method. In embodiments, a steady stream of ions is generated in the ion source. The pulse generator is composed of, for example, an orthogonal accelerator. A lens system, an ion trap, or the like may be provided before the orthogonal acceleration section. The mass spectrometer is, for example, a time-of-flight mass spectrometer. Other types of mass analyzers may be utilized. The emitter current supply circuit is configured, for example, as an analog circuit. A control part is comprised by the processor which runs a program, for example. In an embodiment, the mass spectrometer includes a pulse generator, a reflector and a detector, and an integrator is provided after the mass spectrometer.

In the pulse generator, a plurality of cutout portions and a plurality of non-cutout portions are alternately set for the ion flow. A plurality of ion pulses are configured by a plurality of cutout portions. The pulse generator operates according to a plurality of clipping periods corresponding to the plurality of clipping portions and a plurality of non-snipping periods corresponding to the plurality of non-snipping portions. In the ion source provided upstream of the pulse generator, the plurality of valid periods correspond to the plurality of clipping periods, and the plurality of invalid periods correspond to the plurality of non-snipping periods.

In the embodiment, at least one invalid period among the plurality of invalid periods is the burn-out target period. The burn-out target period includes an emitter burn-out period and a cooling period immediately thereafter. According to this configuration, the emitter can be cleaned in each print-out target period. Cooling after bakeout avoids or reduces the impact on subsequent ion pulse generation. During the cooling period, the emitter may be allowed to stand or be actively cooled by setting the emitter current to 0 A or to a low emitter current that does not cause burn-out of the emitter.

In the embodiment, an accumulator is further provided. The integration unit generates an integrated mass spectrum signal by integrating a plurality of mass spectrum signals in each integration period set intermittently. According to the embodiment, since the blank period after the accumulation period can be matched with the period required for data transfer, the time length of the blank period can be shortened. Therefore, the number of integration periods per unit time can be increased, or the time length of each integration period can be increased.

In an embodiment, the control unit sets at least one print-out target period within each integration period. In the embodiment, the control unit uniformly and dispersively sets a plurality of print-out target periods in each integration period. According to this configuration, it is possible to temporally equalize the degree of contamination (or cleanliness) of the emitter in each integration period. A supplementary burn-out may be performed during the transfer period. Also, bakeout may be performed before and after a data acquisition period (measurement period) that includes multiple integration periods.

In an embodiment, the controller sets the number of times of bake-out in each integration period based on the intensity of the reference peak included in the reference mass spectrum. A mass spectrum (for example, integrated mass spectrum) obtained by measuring a standard sample before compound measurement may be used as the reference mass spectrum. In that case, a molecular ion peak corresponding to a known substance (standard compound) may be used as the reference peak.

In an embodiment, integrated mass spectra are sequentially generated by the integrating section. The control unit sets the number of print-outs in the n+1-th or subsequent integration periods by comparing the n-1-th integrated mass spectrum and the n-th integrated mass spectrum. According to this configuration, the number of times of printing can be adaptively set according to the degree of contamination of the emitter that changes with time. Instead of or together with the number of times of bake-out, the length of time for bake-out, the current value of bake-out, etc. may be changed.

In the embodiment, the accumulation unit alternately defines a plurality of accumulation periods and a plurality of transfer periods. The integrator transfers the integrated mass spectrum signal in each transfer period. The controller controls the operation of the emitter current supply circuit so that the emitter current is supplied to the emitter in at least one transfer period among the plurality of transfer periods. This configuration uses both the inter-pulse burn-out method and the intra-transfer period burn-out method.

A bake-out method according to an embodiment includes a bake-out process and a cooling process. The burnout step is a step of burning out the emitter by supplying an emitter current to the emitter provided in the ion source during the burnout period. The cooling step is a step of cooling the emitter during the cooling period after the bakeout period. In an embodiment bake-out method, a plurality of pulses of ions are generated from an ion stream generated by an ion source. In the ion source, a plurality of effective periods that contribute to the generation of a plurality of ion pulses and a plurality of ineffective periods that do not contribute to the generation of the plurality of ion pulses are alternately set. A bake-out period and a cooling period are set within at least one of the plurality of invalid periods.

This method is time efficient because at least one dead period can be used to bake out the emitter. This method can be implemented as a hardware function or as a software function. In the latter case, a program for executing the above method is installed in the information processing device via a network or via a portable storage medium. The concept of information processing equipment includes computers, mass spectrometers, mass spectrometry systems, and the like.

In the embodiment, at least one of the number of burn-out times, the length of the burn-out period, and the emitter current value is changed based on the information indicating the degree of contamination of the emitter. According to this configuration, it is possible to guarantee necessary burn-out and to avoid excessive burn-out.

(2) Details of Embodiment FIG. 1 shows a mass spectrometry system according to an embodiment. The illustrated mass spectrometry system includes a mass spectrometer and a gas chromatograph (reference numeral 30) provided in front thereof. The gas chromatograph may be omitted and other chromatographs may be provided instead.

A gas chromatograph is an apparatus that has a column through which a mixed sample containing a plurality of compounds is flowed, and separates the plurality of compounds temporally by utilizing their differences in mobility. A plurality of compounds separated by the gas chromatograph are sequentially introduced into the mass spectrometer. Individual compounds are subject to mass spectrometry in the mass spectrometer.

The mass spectrometer is roughly composed of a measurement section 10 and an arithmetic control section 12 . The measurement unit 10 has an ion source 14 and a mass spectrometry unit 16 . The measurement unit 10 also has an integration unit 20 and a power supply unit 22 . In the illustrated configuration example, the mass analysis section 16 has an orthogonal acceleration section 32 , a reflector 36 and a detector 18 . The arithmetic control unit 12 is configured by an information processing device such as a computer in the illustrated configuration example. The arithmetic control unit 12 has a processor 38 , an input unit 40 , a storage unit 42 and a display unit 44 . Processor 38 includes a printout control function, which is shown as printout control 46 in FIG.

The ion source 14 is an ion source according to the field ionization (FI) method. Ion source 14 has an emitter 24 and a cathode 26 . A high voltage is applied between emitter 24 and cathode 26 . Emitter 24 has an emitter wire 28 that produces a high electric field. The surface of the emitter wire 28 is usually formed with a large number of fine needle-like elements. They are called whiskers. A current (emitter current) 29 is passed through the emitter 24 to clean or bake out material deposited on the emitter wire 28 . The amount of current is, for example, between several mA and several tens of mA. As a result, the emitter 24 is heated to a high temperature, and the adhering substances are released. The power supply section 22 has an emitter current supply circuit 22A. The power supply unit 22 also has a circuit that applies a high DC voltage between the emitter 24 and the cathode 26 . The polarity of the high voltage is switched between generating positive ions and generating negative ions.

Each sample separated by the gas chromatograph 30 is sequentially introduced into the ion source 14 . As a result, multiple ions (for example, positive ions) are generated from multiple molecules that make up the sample. Those ions are sent to the mass spectrometer 16 by the action of the extracting voltage. Reference numeral 31 indicates a lens system. The ion source 14 constantly generates an ion current. The flow direction of the ion current is from the left side to the right side in FIG.

The mass spectrometer 16 is an orthogonal acceleration/time-of-flight mass spectrometer in the illustrated configuration example. The orthogonal acceleration section 32 functions as a pulse generator and cuts out a plurality of ion pulses from the ion stream. The pushing direction of each ion pulse 34 is downward in FIG. The ion pulse 34 travels downward. The reflector 36 reverses the traveling direction of individual ions by 180 degrees. It is also called an ion mirror. In FIG. 1, upward traveling ions are detected by detector 18 . During the flight of individual ions from the orthogonal accelerator 32 to the detector 18, the flight velocity of the ions depends on their mass-to-charge ratio (m/z). The ion pulse expands into a zonal stream of ions during its flight. The cut length of the ion current in the orthogonal acceleration section 32 is, for example, 10 cm. However, all numerical values given in the specification of the present application are merely examples.

Ions are detected at the detector 18 . The mass-to-charge ratio of each ion is specified based on the time from the ion pulse generation timing to the detection timing of each ion. A mass spectrum signal is repeatedly output from the detector 18 at timings synchronized with generation of a plurality of ion pulses.

The integrator 20 is an electronic circuit including an A/D converter, an integrator, and the like. Since it is difficult to directly send a large amount of signals output from the detector 18 to the arithmetic control unit 12, the integration unit 20 integrates a plurality of mass spectrum signals within each integration period to obtain an integrated mass spectrum signal. is generated. The number of integrations in one integration period is, for example, between several hundred times and tens of thousands of times, and a specific example is 5000 times. A transfer period is provided after each accumulation period. During the transfer period, the integrated mass spectrum signal (integrated mass spectrum data) is transferred from the integrating section 20 to the processor 38 .

The processor 38 is composed of a CPU that executes programs, and functions as an arithmetic section and a control section. Processor 38 has the ability to generate a total ion current (TIC) chromatogram based on multiple integrated mass spectra, the ability to analyze individual integrated mass spectra, and the like. Also, the processor 38 has a function of controlling the operation of each element constituting the measuring section 10 through control of the power supply section 22 . In the embodiment, the burn-out of the emitter 24 is controlled by a burn-out controller 46 of the processor 38 . Specifically, the burn-out control section 46 controls the burn-out of the emitter 24 by controlling the operation of the emitter current supply circuit 22A. The details of the control will be described in detail later with reference to FIG. 3 and subsequent drawings.

Processor 38 may be configured by a device other than a CPU. Processor 38 may be composed of multiple devices. All or part of the integrating section 20 , the power supply section 22 and the arithmetic control section 12 may be incorporated into the measuring section 10 .

The input unit 40 is configured by a keyboard, pointing device, and the like. The user may specify the print-out conditions using the input unit 40 . The storage unit 42 is configured by a semiconductor memory, a hard disk, or the like. Measurement data and programs are stored there. The display unit 44 is configured by, for example, an LCD. The display unit 44 displays a mass spectrum, a chromatograph, and the like.

FIG. 2 shows the operation according to the comparative example. (A) shows a plurality of ion pulse trains intermittently generated by the orthogonal accelerator. (B) shows a plurality of intermittently set accumulation periods. (C) shows a plurality of intermittently set print-out periods.

In the integrating section, a plurality of integration periods 56 and a plurality of blank periods 58 are alternately set on the time axis. Each blank period 58 corresponds to a transfer period. In the orthogonal acceleration section, a plurality of pulse train generation periods 50 corresponding to a plurality of integration periods 56 and a plurality of rest periods 52 corresponding to a plurality of blank periods 58 are set on the time axis. In each pulse train generation period 50 a pulse train is generated. A pulse train is composed of a plurality of ion pulses 54 arranged on the time axis. During the extraction period, the ions filled in the orthogonal acceleration section are pushed out in the orthogonal direction by the action of the electric field to form an ion pulse. Each integration period 56 (individual pulse train generation period 50) is, for example, 200 ms and each blank period 58 (individual rest period 52) is, for example, 30 ms.

Each blank period 58 (each idle period 52) includes a burn-out period 60 during which an emitter current flows, and a cooling period 62 immediately thereafter. The bake-out period 60 is, for example, 20 ms and the cool-down period 62 is, for example, 10 ms. The emitter current for bakeout is, for example, in the range of 40mA to 100mA. The length of the blank period 58 (idle period 52) is determined so that the print-out period 60 and the cooling period 62 can be sufficiently secured for each integration.

According to the comparative example, it becomes difficult to shorten the blank period 58 (idle period 52). As a result, there arises a problem that the number of times of mass spectrometry per unit time cannot be increased. In other words, the problem arises that the invalid period that exists between each adjacent pulse cannot be exploited.

Based on FIGS. 3 and 4, the operation according to the embodiment, that is, the printing-out method according to the embodiment will be described.

In FIG. 3, (A) shows the printout operation. (B) shows a plurality of intermittently generated ion pulse trains. (C) shows a plurality of intermittently set accumulation periods. A blank period (transfer period) 72 is provided immediately after each accumulation period 70 . According to the embodiment, the blank period 72 can be shortened in comparison with the comparative example shown in FIG.

In the orthogonal acceleration section, a plurality of pulse train generation periods 64 and a plurality of rest periods 66 are alternately set. A plurality of ion pulses 68 are generated in each pulse train generation period 64 . In the ion source, the plurality of periods 78 correspond to the plurality of pulse train generation periods 64 and the plurality of periods 80 correspond to the plurality of rest periods 66 . Each period 80 is, for example, 200 ms, and each period 80 is, for example, 3 ms.

In each period 78, multiple bakeouts 75 are performed in synchronization with the ion pulse generation cycle. Specifically, in the ion source, within each period 78, a plurality of active periods that contribute to the generation of the plurality of ion pulses and a plurality of ineffective periods 94 that do not contribute to the generation of the plurality of ion pulses alternate. occur. In an embodiment, emitter bake-out 75 is performed during one or more invalid periods 94 . The emitter bakeout 75 may be performed during the entire invalid period 94 included in the period 78 or the emitter bakeout 75 may be performed during the partial invalid period 94 included within the period 78 . In that case, the bakeout 75 is performed uniformly and distributed throughout the period 78 . For example, one burnout 75 may be performed every k invalid periods.

In an embodiment, in addition to the burnout 75 within multiple invalid periods 94 , a secondary burnout 82 may be performed within each period 80 . The bakeout 84 may be performed before starting the measurement, and the bakeout 86 may be performed after the measurement is finished.

FIG. 4 shows a portion of the operation shown in FIG. 3 in enlarged and detailed view. (A) shows a printout operation. (B) shows the ion current generated by the ion source. (C) shows an ion pulse train. (D) shows the operation of the detector.

The generated individual ion pulse 68 is elongated in time as it flies and reaches the detector. Its temporal extent is indicated at 90 . Ion pulse interval 74 is, for example, in the range of 40 μs to 60 μs. The width of each ion pulse 68 is several μs.

The ion stream alternates between a plurality of effective portions 92A that contribute to the generation of the plurality of ion pulses 68 and a plurality of ineffective portions 94A that do not contribute to the generation of the plurality of ion pulses. In the ion source, active portions 92A occur in active periods 92 and inactive portions 94A occur in inactive periods 94. FIG. For example, half of the ion pulse period corresponds to active period 92 and the other half corresponds to inactive period 94 .

In the embodiment, the burn-out is performed in all or part of the invalid periods (burn-out target period) 94 selected as the burn-out target period. The invalid period 94 includes a burn-out period 96 followed immediately by a cooling period 98 . A margin period 100 is set just before the print-out period 96, if necessary. For example, the bakeout period is 10 μs and the cool down period is 5 μs. During the burn-out period 96, an emitter current (current pulse) 76 for burn-out is supplied to the emitter. The size and current value of each period can be specified by the user or automatically specified.

5 and 6 show a first embodiment for automatically determining the number of bakeouts. As shown in FIG. 5, a standard sample is measured prior to sample measurement. As a result, a reference spectrum 101 is obtained as an integrated spectrum. Reference spectrum 101 includes reference peak 102, which is a known molecular peak. For example, a plurality of intervals are set on the intensity axis, and the number of burn-out times per integration period is automatically determined based on which interval the intensity of the reference peak 102 belongs to. For example, if the intensity of the reference peak 102 exceeds 100% of the reference value, 0 times is set as the number of bake-out times. If the intensity of the reference peak 102 is less than the reference value, the number of burn-out times is set according to the magnitude of the difference between the intensity and the reference value. For example, when the intensity of the reference peak 102 is 80% of the reference value, 1000 times are set as the number of times of printing. When the intensity of the reference peak 102 is less than 10% of the reference value, the number of times of printing out is set to the maximum value, eg, 5000 times. In this way, the intensity of the reference peak is referred to as indicating the degree of contamination of the emitter, and the number of burn-out times is variably set based on this.

FIG. 6 shows the operation of the first embodiment as a flow chart. In S10, an integrated spectrum is acquired as a reference spectrum. In S12, the intensity of the reference peak included in the reference spectrum is referenced. In S14, the number of print-outs in one integration period is set based on the intensity of the reference peak. At S16, mass spectrometry of the sample is performed. At that time, the print-out control is executed according to the number of print-out times. If necessary, the number of bake-out times may be reset during the measurement. Note that the intensity of the reference peak is defined by the peak apex level, peak area, and the like. In S18, it is determined whether or not to continue this process.

7 and 8 show a second embodiment for automatically determining the number of bakeouts. In a second embodiment, the number of bakeouts is set dynamically. The left side of FIG. 7 shows the (n−1)th integrated spectrum 104n−1. n is an integer greater than or equal to 1, that is, n=1, 2, 3, . . . The right side of FIG. 7 shows the n-th integrated spectrum 104n. The (n-1)th integrated spectrum 104n-1 includes the (n-1)th reference peak 102n-1. The nth integrated spectrum 104n includes the nth reference peak 102n.

In a second embodiment, the intensity of the n-1th reference peak and the intensity of the nth reference peak are compared. When the intensity of the (n−1)th reference peak is 100%, the calculation is made as to whether the intensity of the nth reference peak corresponds to +% or -%. A new print-out count is calculated according to the sign and magnitude of the difference. For example, in the example shown in FIG. 7, as indicated by reference numeral 106, a negative value is generated as the difference.

For example, if the intensity of the nth reference peak corresponds to +20%, then 20% is subtracted from the current number of bakeouts, which becomes the new number of bakeouts. If the intensity of the n-th reference peak corresponds to 0%, the current bakeout number is maintained. If the intensity of the nth reference peak corresponds to -20%, then the current bakeout number is increased by 20% to become the new bakeout number. If the current bakeout number corresponds to -90%, then the current bakeout number is increased by 90% to become the new bakeout number. The second embodiment reduces or maintains the number of bakeouts when the degree of contamination of the emitter tends to decrease or is appropriate, and increases the number of bakeouts when the degree of contamination of the emitter tends to increase. It is something that makes

FIG. 8 shows the operation of the second embodiment. In S20, the intensity of the n-th reference peak in the n-th integrated spectrum is referred to. In S22, the intensity of the (n−1)th reference peak in the (n−1)th integrated spectrum and the intensity of the nth reference peak in the nth integrated spectrum are compared, and the difference between them is calculated. In S24, the number of times of printing is set based on the sign and magnitude of the difference. In S26, the printout of the emitter is controlled based on the set number of printouts. For example, in the (n+1)th integration period, the print-out control is executed according to the set number of print-out times. In S28, it is determined whether or not to continue this process, and when continuing, each process after S20 is repeatedly executed.

For example, among multiple invalid periods included in the cumulative period, if multiple invalid periods corresponding to some of them are subject to burnout, the periods subject to burnout should be distributed evenly throughout the cumulative period. , they are set. Such a setting makes it possible to even out the degree of emitter contamination over the entire integration period.

Instead of the number of burn-out times, the emitter current value or the emitter current period may be dynamically changed. For example, the emitter current value or the emitter current period may be changed according to the degree of contamination of the emitter, assuming that the burn-out is performed in all invalid periods.

In the above embodiment, one bake-out was performed per ion pulse, but multiple bake-outs per ion pulse may be performed. As shown in FIG. 3, if the print-out effect is insufficient even if the print-out is performed multiple times within the integration period, the print-out may be performed within the transfer period.

10 measurement unit 12 arithmetic control unit 14 ion source 16 mass spectrometry unit 18 detector 20 integration unit 22 power supply unit 24 emitter 26 cathode 32 orthogonal acceleration unit (pulse generator) 36 reflector 38 processor, 46 bake-out control;

Claims (9)

an ion source comprising an emitter for generating a stream of ions;
a pulse generator for cutting out a plurality of pulses of ions from the ion stream;
a mass spectrometer that generates a plurality of mass spectrum signals by mass spectrometry of the plurality of ion pulses;
an emitter current supply circuit that supplies an emitter current for burn-out to the emitter;
a control unit that controls the operation of the emitter current supply circuit;
an integrator that generates an integrated mass spectrum signal by integrating the plurality of mass spectrum signals in each intermittently set integration period;
including
In the ion source, in each integration period, a plurality of effective periods that contribute to the generation of the plurality of ion pulses and a plurality of ineffective periods that do not contribute to the generation of the plurality of ion pulses alternately occur. ,
The control unit controls the operation of the emitter current supply circuit so that the emitter current is supplied to the emitter during all or part of the plurality of invalid periods.
A mass spectrometry system characterized by: In the mass spectrometry system according to claim 1,
at least one of the plurality of invalid periods is a burn-out target period;
The burn-out target period includes a burn-out period of the emitter and a cooling period immediately thereafter.
A mass spectrometry system characterized by: In the mass spectrometry system according to claim 1 ,
The control unit changes at least one of the number of times of burn-out, the length of the burn-out period, and the emitter current value, based on the information representing the degree of contamination of the emitter.
A mass spectrometry system characterized by: In the mass spectrometry system according to claim 1 ,
The control unit uniformly and dispersively sets a plurality of print-out target periods in each integration period.
A mass spectrometry system characterized by: In the mass spectrometry system according to claim 1 ,
The control unit sets the number of times of printing out in each integration period based on the intensity of the reference peak included in the reference mass spectrum.
A mass spectrometry system characterized by: In the mass spectrometry system according to claim 1 ,
The control unit compares the n−1th integrated mass spectrum and the nth integrated mass spectrum to set the number of times of printing out in the n+1th or subsequent integration period.
A mass spectrometry system characterized by: In the mass spectrometry system according to claim 1 ,
in the integration unit, a plurality of integration periods and a plurality of transfer periods are alternately determined;
The integration unit transfers the integrated mass spectrum signal in each transfer period,
The control unit controls the operation of the emitter current supply circuit so that the emitter current is supplied to the emitter in at least one transfer period among the plurality of transfer periods.
A mass spectrometry system characterized by: A bake-out method in a mass spectrometry system, comprising:
a step of supplying an emitter current to an emitter provided in the ion source during a bake-out period to bake-out the emitter;
cooling the emitter during a cooling period after the bakeout period;
including
generating a plurality of pulses of ions from an ion stream generated by the ion source;
mass spectrometrically analyzing the plurality of ion pulses to generate a plurality of mass spectral signals;
generating an integrated mass spectrum signal by integrating the plurality of mass spectrum signals in each intermittently set integration period;
In the ion source , a plurality of effective periods that contribute to the generation of the plurality of ion pulses and a plurality of ineffective periods that do not contribute to the generation of the plurality of ion pulses are alternately set in each integration period,
wherein the burn-out period and the cooling period are set within at least one of the plurality of invalid periods;
A baking method characterized by The bakeout method of claim 8,
At least one of the number of times of burn-out, the length of the burn-out period, and the emitter current value is changed based on the information representing the degree of contamination of the emitter.
A baking method characterized by

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