JP5407616B2 - Ion trap device - Google Patents

Description

  The present invention relates to an ion trap apparatus that captures ions or selects ions by the action of a high-frequency electric field, and more particularly to an ion trap apparatus that uses a rectangular wave voltage as a voltage for generating a high-frequency electric field.

  In a mass spectrometer, an ion trap captures and confines ions by the action of a high-frequency electric field, sorts out ions with a specific mass (strictly, mass-to-charge ratio m / z), and so on. It is used to cleave ions. As will be described later, a typical ion trap has a single ring electrode whose inner surface is a rotating one-leaf hyperboloid shape, and an inner surface disposed opposite to the ring electrode is a rotating two-leaf hyperboloid shape. Although it is a three-dimensional quadrupole ion trap composed of a pair of end cap electrodes, a linear ion trap composed of four rod electrodes arranged in parallel is also known. In this specification, for the sake of convenience, the ion trap will be described by taking “three-dimensional quadrupole type” as an example.

  In a conventional general ion trap, a high frequency electric field for capturing ions is usually formed in a space surrounded by the ring electrode and the end cap electrode by applying a sinusoidal high frequency voltage to the ring electrode. Confinement while oscillating ions. On the other hand, in recent years, ion traps that confine ions by applying a rectangular wave voltage to a ring electrode instead of a sinusoidal high frequency voltage have been developed (Patent Document 1, Patent Document 2, Non-Patent Document 1). Etc.) This type of ion trap is generally called a digital ion trap (DIT) because a rectangular wave voltage having binary voltage levels of high and low is used.

  The conventional analog-driven ion trap uses an LC resonator to generate a sinusoidal high-frequency voltage, and controls the mass range of ions that can be captured by changing the amplitude of the sinusoidal voltage. . On the other hand, a digital ion trap generates a rectangular high-frequency voltage by switching two DC voltages at high speed, and can be captured by changing the frequency while keeping the amplitude of the rectangular wave voltage constant. Control the mass range of ions. Therefore, since the amplitude of the high voltage applied to the ring electrode is smaller than that in the analog driving method, the high frequency voltage generating circuit can be configured at low cost. In addition, there is an advantage that generation of undesired discharge between the electrodes can be avoided.

  In the digital ion trap, the voltage level of the rectangular wave voltage applied to the ring electrode is as high as about ± several hundred V to ± 1 kV, and the frequency is as wide as several tens of kHz to several MHz. In order to generate such a rectangular wave voltage, the high-frequency voltage generation circuit is configured to switch between a positive high voltage and a negative high voltage by a high-speed semiconductor switching element such as a power MOSFET (Patent Document 2). Non-Patent Document 1). Since heat is generated during the switching operation of such a semiconductor switching element, the temperature of the high-frequency voltage generation circuit for the digital ion trap becomes considerably high, and the temperature depends on the frequency of the switching operation.

  In the mass spectrometer using the ion trap as described above, in general, in the standby state where the analysis is not performed, in order to sweep out undesired ions remaining in the ion trap, A rectangular wave voltage having a low frequency (for example, 20 kHz or less) that is significantly out of the normal frequency range is applied to the ring electrode. When the analysis is started from such a standby state, the frequency of the rectangular wave voltage applied to the ring electrode is increased, so that the temperature of the high-frequency voltage generation circuit is higher than that in the standby state. With such a temperature change, for example, the electrical characteristics such as the on-resistance of the semiconductor switching element change, and the amplitude of the rectangular wave voltage changes slightly. Therefore, when the frequency of the rectangular wave voltage is switched from a low frequency to a high frequency during analysis, the amplitude of the rectangular wave voltage gradually fluctuates (that is, drifts) until the temperature of the high frequency voltage generating circuit rises and stabilizes. .

  In an ion trap mass spectrometer using matrix-assisted laser desorption ionization (MALDI) as an ion source, ions are generated by laser light irradiation → introduction of ions into the ion trap → ion trapping (cooling) → ions by mass scanning It is common to obtain mass spectral data with a high S / N by repeating the process of discharging and detecting the liquid many times and integrating the obtained mass profiles on a computer (see Patent Document 3, etc.) ). The timing at which ions having a certain mass are ejected from the ion trap during mass scanning depends on the frequency and amplitude of the rectangular wave voltage. For this reason, when the amplitude of the rectangular wave voltage gradually changes due to the temperature change as described above, the ion ejection time of the same mass is gradually shifted for each analysis at the time of repeated analysis. As a result of integrating the mass profiles in which the deviation occurs in this way, the mass resolution of the mass spectrum is lowered.

  In order to reduce the influence of the time drift of ion ejection by mass scanning as described above, until the time drift is settled during repeated analysis, that is, until the temperature of the high-frequency voltage generation circuit becomes stable to some extent. A method of not acquiring a mass profile is conceivable. However, in such a method, the sample is consumed wastefully, and there is a problem that the measurement throughput is lowered because it is necessary to increase the number of repetitions of the analysis.

Special Table 2007-527002 JP 2008-282594 A International Publication WO2008 / 129850 Pamphlet

Furuhashi, Takeshita, Ogawa, Iwamoto, Din, Gills, Smirnov, “Development of Digital Ion Trap Mass Spectrometer”, Shimazu Review, Shimazu Review Editorial Department, March 31, 2006, Vol. 62, No. 3, No. 4, pp.141-151

  The present invention has been made to solve the above-mentioned problems, and its main purpose is to reduce the influence of time drift of ion ejection accompanying the temperature change of the high-frequency voltage generation circuit, and to perform mass analysis with high mass resolution. An object of the present invention is to provide an ion trap apparatus that can be executed and can improve measurement throughput.

The first invention made to solve the above problems is generated by switching a plurality of voltages by a switching element in order to form an ion trap composed of a plurality of electrodes and a high-frequency electric field in the internal space of the ion trap. A voltage generator that applies a rectangular wave voltage to at least one of the plurality of electrodes;
a) pulse generation means for generating a drive pulse of a predetermined frequency and supplying the drive pulse to the switching element of the voltage generation unit;
b) including a standby frequency calculation means for calculating the frequency of the drive pulse necessary for maintaining the temperature of the voltage generator assumed under the analysis conditions of the series of analysis, and the series of analysis is completed. The frequency according to the temperature of the voltage generator assumed under the analysis conditions of the next series of analysis calculated by the standby frequency calculation means during the standby period until the next series of analyzes is executed. Control means for controlling the pulse generation means so as to generate a drive pulse of
It is characterized by having.

  The analysis conditions include, for example, information such as the mass range and mass resolution of ions to be captured or analyzed in the ion trap. Therefore, if the analysis conditions are different, the frequency of the rectangular wave voltage applied to the electrodes constituting the ion trap from the voltage generation unit at the time of analysis execution is different, and therefore, when the analysis is repeated under the analysis conditions The temperature reached (stable) by the voltage generator is also different. Therefore, for example, the relationship between the analysis condition or the frequency (one or a plurality of frequencies) of the rectangular wave voltage at the time of analysis and the temperature reached by the voltage generation unit is examined in advance and is necessary to maintain the temperature. The frequency of the drive pulse is calculated and stored in the storage unit in association with the analysis condition or the frequency of the rectangular wave voltage at the time of analysis.

  The standby frequency calculation means obtains an appropriate drive pulse frequency with reference to information stored in the storage unit, for example, when given a series of analysis conditions. Alternatively, the analysis condition or the relationship between the frequency of the rectangular wave voltage at the time of analysis and the temperature reached by the voltage generation unit is stored in the storage unit, and the standby frequency calculation means is given a certain series of analysis analysis conditions. If so, a target temperature to be maintained during standby may be obtained by referring to the information stored in the storage unit, and the frequency of the drive pulse that maintains this temperature may be calculated.

  In the ion trap device according to the first aspect of the present invention, after a series of analyzes (repeated analysis for one sample) is completed, during the waiting period until the next series of analyzes is executed, Drive pulses having different frequencies according to the analysis conditions are supplied to the switching element of the voltage generator. Accordingly, the temperature of the voltage generation unit is maintained at a temperature substantially equal to the temperature at the time of the next analysis even during the standby period until the next series of analysis is started. Since the change in temperature of the voltage generation unit after the standby period ends and the process proceeds to analysis may be small, there is almost no variation in the amplitude of the rectangular wave voltage generated by the voltage generation unit. As a result, the time drift of ion ejection in repetitive analysis is reduced, and for example, when performing repetitive analysis on one sample, the mass profile obtained from the start time of analysis can be integrated.

  Further, when the ion trap apparatus is activated instead of the standby state as described above, the temperature of the voltage generation unit is normally low, so that, for example, the ion trap apparatus according to the first invention is executed during the standby period. Even if the control is performed, it takes some time for the temperature of the voltage generating unit to reach the temperature assumed in the first analysis. Therefore, in order to sufficiently raise the temperature of the voltage generating unit until the first series of analysis is executed, the following configuration is preferable.

That is, the second invention made in order to solve the above-mentioned problem is to switch a plurality of voltages by a switching element in order to form an ion trap composed of a plurality of electrodes and a high-frequency electric field in the internal space of the ion trap. A voltage generator that applies the rectangular wave voltage generated in step 1 to at least one of the plurality of electrodes,
a) pulse generating means for generating a driving pulse of a predetermined frequency and supplying the driving pulse to the switching element;
b) A frequency of the driving pulse and a time for supplying the driving pulse necessary to raise the temperature of the voltage generating unit from the temperature in the initial operation state to a temperature assumed under a series of analysis conditions. An initial driving condition calculating means for calculating, and in the initial stage of operation, the driving pulse having a relatively high frequency calculated by the initial driving condition calculating means is generated for a time calculated by the initial driving condition calculating means. Control means for controlling the pulse generating means;
It is characterized by having.

  In the ion trap apparatus according to the second invention, the temperature of the voltage generating unit is substantially the same as the ambient temperature at the initial stage of operation of the apparatus, specifically, for example, immediately after the power is turned on. The pulse generating means generates a drive pulse with a relatively high frequency, and the switching element of the voltage generating unit is turned on / off at a high frequency. Here, “relatively high frequency” means a high frequency in a frequency range generally used in analysis or a frequency higher than the frequency range. The higher the frequency of the drive pulse that drives a switching element such as a power MOSFET, the greater the amount of heat generated.Therefore, the temperature of the voltage generator is increased rapidly, and the temperature is assumed under the analysis conditions of a series of analyses. You can get closer.

In the second invention, similarly to the first invention, based on the result of a preliminary examination of the relationship between the analysis conditions or one or more frequencies of the rectangular wave voltage at the time of analysis and the ultimate temperature of the voltage generator, Calculate the frequency of the drive pulse and the time for supplying the drive pulse necessary to quickly raise the temperature from the temperature in the initial operation state to the above-mentioned temperature, and set the analysis condition or the frequency of the rectangular wave voltage during the analysis. Correspondingly stored in the storage unit. Then, the initial driving condition calculating means when the given analysis conditions, for example one set of analysis, by referring to the information stored in the storage unit Ru obtains the frequency and time of the drive pulse.

  Of course, the ion trap apparatus according to the first invention and the ion trap apparatus according to the second invention can be combined, so that the initial operation of the apparatus, a series of analyzes and the next series of analyzes can be performed. In any of the standby periods, the temperature of the voltage generation unit can be brought close to the temperature at the time of the next analysis.

  In the ion trap apparatus according to the first and second inventions, typically, the ion trap is a three-dimensional quadruple composed of one ring electrode and a pair of end cap electrodes arranged opposite to each other with the ring electrode interposed therebetween. Although it is a polar ion trap, it may be a linear ion trap. In the case of a three-dimensional quadrupole ion trap, the voltage generator applies a high-voltage rectangular wave voltage to the ring electrode, so that ions having a specific mass or mass range can be efficiently collected in the internal space of the ion trap. Can be trapped in and discharged from the ion trap.

  According to the ion trap apparatus according to the first and second inventions, immediately before the start of a series of analysis, the temperature of the voltage generation unit using a switching element such as a power MOSFET, for example, is the temperature in the series of analysis. And can be almost the same. As a result, fluctuations in the amplitude of the rectangular wave voltage during analysis can be suppressed, and time drift when ions are ejected from the ion trap by mass scanning is reduced. As a result, mass resolution is improved when a mass spectrum is created by integrating mass profiles obtained by repeated analysis of the same sample. In addition, since it is not necessary to perform useless repeated analysis in order to make the temperature of the voltage generator stable, loss of the sample can be suppressed. Furthermore, measurement throughput is improved by avoiding unnecessary repeated analysis that is not reflected in the mass spectrum.

The block diagram of the principal part of one Example of the ion trap mass spectrometer using the ion trap apparatus which concerns on this invention. The flowchart which shows the procedure of a series of processes (operation) performed for mass spectrometry in the ion trap mass spectrometer of a present Example. The flowchart of the temperature stabilization control in an initial state. The flowchart of the temperature stabilization control in a standby state. Schematic which shows an example of the temperature change of a main power supply part.

  An embodiment of an ion trap mass spectrometer using the ion trap apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a main part of the ion trap mass spectrometer of the present embodiment.

  The ion trap mass spectrometer according to this embodiment includes an ionization unit 1 that ionizes a target sample, and a three-dimensional quadrupole ion trap 2 that separates ions according to mass (strictly, mass to charge ratio m / z). And a detector 3 for detecting ions.

  The ionization unit 1 uses a matrix-assisted laser desorption ionization method (MALDI), a laser irradiation unit 11 that emits pulsed laser light, a sample plate 12 to which a sample S including a target sample component is attached, a laser It includes an extraction electrode 13 for extracting ions emitted from the sample S by light irradiation, an ion lens 14 for guiding the extracted ions, and the like. Of course, other laser ionization methods other than MALDI and ionization methods that do not use laser light may be used.

  The ion trap 2 is composed of one annular ring electrode 21 and an inlet side end cap electrode 22 and an outlet side end cap electrode 24 which are arranged to face each other so as to sandwich the ring electrode 21. A space surrounded by the electrodes 21, 22, and 24 is an ion trapping region. An ion incident port 23 is bored substantially at the center of the entrance-side end cap electrode 22, and ions emitted from the ionization unit 1 pass through the ion incident port 23 and are introduced into the ion trap 2. On the other hand, an ion emission port 25 is formed substantially at the center of the outlet-side end cap electrode 24, and ions discharged from the ion trap 2 through the ion emission port 25 reach the detection unit 3 and are detected.

  The detection unit 3 includes a conversion dynode 31 that converts ions into electrons, and a secondary electron multiplier 32 that multiplies and detects electrons arriving from the conversion dynode 31, and detects according to the amount of incident ions. The signal is sent to the data processing unit 8.

The main power supply unit 4 corresponding to the voltage generation unit in the present invention for driving the ion trap 2 includes a first voltage source 41 for generating the first voltage V _H and a second voltage V _L (V _L <V _H ). a second voltage source 42 for generating a first switching element 43 and second switching element 44 connected in series between the output terminals of the second voltage source 42 of the first voltage source 41, the In addition, a rectangular wave output voltage V _OUT is taken out from the connection connecting both the switching elements 43 and 44 in series, and applied to the ring electrode 21. The auxiliary power supply 5 applies a DC voltage or a rectangular wave voltage to the end cap electrodes 22 and 24, respectively. Since the first voltage and the second voltage are usually ± several hundreds V or more and the switching elements 43 and 44 are required to have high withstand voltage and high speed, a power MOSFET is usually used for the switching elements 43 and 44. It is done.

The timing signal generator 6 corresponding to the pulse generator in the present invention is a hardware logic circuit, and is controlled by the controller 7 corresponding to the controller in the present invention under the control of the first switching element 43 and the second switching element. A drive pulse for controlling ON / OFF of 44 is generated and applied to the main power supply unit 4, and for example, a pulse obtained by dividing one of these drive pulses with an appropriate frequency division ratio is applied to the auxiliary power supply unit 5. The first switching element 43 and the second switching element 44 are driven so as to be alternately turned on (but not to be turned on at the same time). Since the first voltage V _H is output when the first switching element 43 is turned on and the second voltage V _L is output when the second switching element 44 is turned on, the output voltage V _OUT is ideally high. A rectangular wave voltage having a level of V _H and a low level of V _L is obtained. When the frequency of the pulse for driving the switching elements 43 and 44 is changed by the timing signal generator 6, the frequency of the rectangular wave voltage changes while the amplitude (voltage level) is kept constant.

  The control unit 7 is mainly composed of a personal computer, and its function is achieved by executing a control / processing program preinstalled in the personal computer. The control unit 7 includes, as characteristic function blocks, an initial frequency / drive time determination unit 71 corresponding to the initial drive condition calculation unit in the present invention, a standby frequency determination unit 72 corresponding to the standby frequency calculation unit in the present invention, A temperature control data storage unit 73.

  FIG. 2 is a flowchart showing a sequence of processes (operations) executed for mass analysis of ions in the ion trap mass spectrometer of the present embodiment. The initial state of step S1 is a state immediately after the apparatus is activated, and thereafter, the state shifts to a standby state and waits for execution of analysis (step S2). Immediately before the start of a series of analyses, an operation of discharging undesired ions remaining in the ion trap 2 is performed (step S3), and then an analysis for a certain sample is performed.

  That is, a laser beam is emitted from the laser irradiation unit 11 for a short time and applied to the sample S under the control of the control unit 7. The matrix in the sample S is rapidly heated by laser light irradiation, and vaporizes with the target component. At this time, the target component is ionized. The generated ions are converged by an electrostatic field formed by the ion lens 14, introduced into the ion trap 2 through the ion incident port 23, and captured (step S4). Since the irradiation time of the laser beam is very short, the generation time of ions is also short. Therefore, the generated ions reach the ion entrance 23 in a packet form.

  Then, cooling is performed by bringing the ions into contact with the cooling gas introduced into the ion trap 2 prior to ion introduction (step S5), and then ions are ejected in order of mass by mass scanning through the ion emission port 25. (Step S6). The discharged ions are sequentially detected by the detection unit 3. The data processing unit 8 acquires one mass profile corresponding to one mass scan. Since the mass range of ions stably trapped in the ion trap 2 depends on the frequency of the rectangular wave voltage applied to the ring electrode 21, during the series of operations for ions in the ion trap 2 as described above. The timing signal generator 6 supplies a driving pulse having a predetermined frequency to the switching elements 43 and 44, and a rectangular wave voltage having a frequency corresponding to the driving pulse is generated by the main power supply unit 4 and applied to the ring electrode 21.

  As described above, since the amount of ions generated by one laser irradiation is not so large, the process returns from step S7 to S4, and the operations of steps S4 to S6 are repeated a predetermined number of times (for example, 10 times). The data processing unit 8 integrates a predetermined number of mass profiles to create a mass spectrum. When a series of analyzes for one sample is completed, the ion trap 2 is in a standby state until the next sample is analyzed.

  In the flowchart shown in FIG. 2, every time ions are introduced into the ion trap 2, ions are discharged from the ion trap 2 and detected. For example, International Publication No. 2008/126383, International Publication No. 2008/129850 are disclosed. As disclosed in the pamphlet, ions generated from the sample S by multiple times of laser light irradiation are sequentially introduced into the ion trap 2 to increase the amount of trapped ions, and then ions are detected by mass scanning. May be discharged from the ion trap 2 and detected.

  During the mass scanning, the frequency of the rectangular wave voltage applied to the ring electrode 21 is scanned. The frequency change is sufficiently faster than the temperature change of the switching elements 43 and 44, and is repeated for one sample. Since these analyzes are performed under the same analysis conditions, the temperature reached by the main power supply unit 4 is substantially determined in accordance with the analysis conditions of the repeated analysis. Therefore, the relationship between the analysis conditions such as the mass range of ions to be analyzed and the stable temperature reached by the main power supply unit 4 is measured in advance, and data indicating the relationship is stored in the temperature control data storage unit 73. To leave.

  Since the temperature in question here is not so strict, individual differences between the switching elements 43 and 44 can be almost ignored. Therefore, it is sufficient that the data indicating the relationship between the analysis conditions and the stable temperature is previously measured by the device manufacturer and stored in the temperature control data storage unit 73 such as a flash ROM. The same applies to the relationship between the mass range of ions to be analyzed (or the mass of specific ions) and the stable temperature, not the relationship between the analysis conditions and the stable temperature.

  Next, temperature stabilization control, which is a characteristic control operation in the ion trap mass spectrometer of the present embodiment, will be described with reference to FIGS.

  FIG. 3 is a flowchart of temperature stabilization control in the initial state in FIG. In the initial state, it can be considered that the temperature of the main power supply unit 4 including the switching elements 43 and 44 is substantially the same as the ambient temperature (room temperature).

  In the control unit 7, the initial frequency / driving time determination unit 71 executes the first time, that is, extracts analysis conditions for a series of analyzes for the first sample (step S 11), and refers to the temperature control data storage unit 73. A stable temperature T1 corresponding to the analysis conditions is obtained (step S12). Then, a frequency f0 and a drive time t0 appropriate for reaching the stable temperature T1 are calculated from the difference between the initially assumed initial temperature T0 and the stable temperature T1 (step S13). In the temperature stabilization control in the initial state, the purpose is to raise the temperature as quickly as possible. Therefore, the frequency f0 of the drive pulse should be selected as high as possible within the range that the circuits such as the switching elements 43 and 44 can handle. .

  The frequency and driving time of the driving pulse can be calculated as follows, for example. The frequency f0 of the drive pulse is determined in advance as 1 MHz, for example, under the above constraints. Then, the temperature rise rate ΔT of the main power supply unit 4 when the switching elements 43 and 44 are driven with the drive pulse of the frequency f0 is measured in advance, and the drive time is calculated from the temperature difference between the initial temperature and the stable temperature. A calculation formula is obtained and stored in the initial frequency / drive time determination unit 71. At the time of actual measurement, the initial frequency / drive time determination unit 71 obtains the temperature difference between the initial temperature T0 and the stable temperature T1 as described above, and calculates the drive time t0 from the temperature difference based on the above formula. . However, since it is necessary to avoid an overshoot at an extreme temperature, it is preferable to set a calculation formula that takes this into consideration.

  The initial temperature T0 may be preliminarily assumed to be 30 ° C., for example, but a temperature sensor may be installed in the vicinity of the main power supply unit 4 to measure the actual initial temperature. In addition, in order to reduce the temperature overshoot as described above, the frequency f0 of the drive pulse is not set to only one type, but the frequency is lowered initially as a high frequency so that the main power supply 4 The degree of temperature rise may be gradually reduced.

  In any case, when the initial frequency f0 and the driving time t0 are determined in the initial frequency / driving time determining unit 71, the control unit 7 controls the timing signal generating unit 6 so as to generate a driving pulse corresponding thereto, A driving pulse is supplied from the timing signal generator 6 to the switching elements 43 and 44 (step S14). As a result, the switching elements 43 and 44 perform a switching operation at a higher speed than in normal analysis, thereby generating a large amount of heat. As a result, as shown in FIG. 5, the temperature of the main power supply unit 4 rapidly rises from the initial temperature T0 and reaches the vicinity of the stable temperature T1. Even before the first analysis, after the temperature stability control as described above in the initial state is performed, the process proceeds to the temperature stability control in the standby state as described below.

  FIG. 4 is a flowchart of temperature stabilization control in the standby state in FIG. In the standby state, the standby frequency determination unit 72 in the control unit 7 extracts analysis conditions for a series of analyzes to be executed next (step S21), and corresponds to the analysis conditions with reference to the temperature control data storage unit 73. The obtained stable temperature is obtained (step S22). Here, the stable temperature is assumed to be T2. Then, a standby frequency f1 suitable for maintaining the stable temperature T2 is calculated (step S23). In general, this standby frequency f1 can be the frequency used to capture ions in the next analysis to be performed.

  When the standby frequency determination unit 72 determines the standby frequency f1, the control unit 7 controls the timing signal generation unit 6 to generate a drive pulse corresponding to the standby frequency f1, and the timing signal generation unit 6 controls the switching element 43, A drive pulse is supplied to 44 (step S24). As a result, as shown in FIG. 5, the temperature of the main power supply unit 4 reaches the vicinity of the stable temperature T2 of the analysis of the next sample after the first sample analysis is completed.

  In this way, in a state where the temperature of the main power supply unit 4 is almost stable, the switching elements 43 and 44 are switched to remove ions remaining in the ion trap 2 immediately before the execution of the analysis of the next sample. The frequency of the drive pulse is lowered to a low frequency (for example, 20 kHz or less), and the frequency of the rectangular wave voltage applied to the ring electrode 21 is lowered. At this time, although the switching operation of the switching elements 43 and 44 is delayed, the time required for removing the residual ions is only about several tens of milliseconds, and even if the frequency of the drive pulse is lowered during this time, the main operation is performed. There is almost no temperature change of the power supply unit 4. Therefore, when starting the next analysis, the main power supply unit 4 is in a state close to the temperature corresponding to the analysis, and a mass profile having no time drift can be acquired from the beginning of the analysis.

  In the above embodiment, the relationship between the analysis conditions and the stable temperature of the main power supply unit 4 is measured in advance, and the frequency of the drive pulse and the drive pulse are supplied so as to achieve the target temperature using the relationship. I try to decide the time. Therefore, although it is not always guaranteed that the temperature of the main power supply unit 4 becomes the target temperature as a result of such control, it is not necessary to perform highly accurate temperature control in the first place as described above. There is no problem. However, actually, a temperature sensor may be installed in the vicinity of the main power supply unit 4, and the control unit 7 may appropriately modify the frequency and driving time of the driving pulse while monitoring the temperature detected by the temperature sensor. .

  Further, the above-described embodiment is merely an example, and it is obvious that modifications, corrections, and additions may be appropriately made within the scope of the present invention, and included in the scope of claims of the present application. For example, although the above embodiment is a three-dimensional quadrupole ion trap, the present invention can be applied to a linear ion trap as long as it is a digital drive system.

DESCRIPTION OF SYMBOLS 1 ... Ionization part 11 ... Laser irradiation part 12 ... Sample plate 13 ... Extraction electrode 14 ... Ion lens 2 ... Ion trap 21 ... Ring electrode 22 ... Inlet side end cap electrode 23 ... Ion entrance 24 ... Outlet side end cap electrode 25 ... Ion exit 3 ... detection unit 31 ... conversion dynode 32 ... secondary electron multiplier 4 ... main power supply unit 41 ... first voltage source 42 ... second voltage source 43, 44 ... switching element 5 ... auxiliary power supply unit 6 ... timing Signal generation unit 7 ... control unit 71 ... initial frequency / drive time determination unit 72 ... standby frequency determination unit 73 ... temperature control data storage unit 8 ... data processing unit

Claims (3)

Applying a rectangular wave voltage generated by switching a plurality of voltages by a switching element to at least one of the plurality of electrodes in order to form a high frequency electric field in an ion trap and an internal space of the ion trap In the ion trap apparatus comprising:
a) pulse generation means for generating a drive pulse of a predetermined frequency and supplying the drive pulse to the switching element of the voltage generation unit;
b) including a standby frequency calculation means for calculating the frequency of the drive pulse necessary for maintaining the temperature of the voltage generator assumed under the analysis conditions of the series of analysis, and the series of analysis is completed. The frequency according to the temperature of the voltage generator assumed under the analysis conditions of the next series of analysis calculated by the standby frequency calculation means during the standby period until the next series of analyzes is executed. Control means for controlling the pulse generation means so as to generate a drive pulse of
An ion trap apparatus comprising: Applying a rectangular wave voltage generated by switching a plurality of voltages by a switching element to at least one of the plurality of electrodes in order to form a high frequency electric field in an ion trap and an internal space of the ion trap In the ion trap apparatus comprising:
a) pulse generating means for generating a driving pulse of a predetermined frequency and supplying the driving pulse to the switching element;
b) A frequency of the driving pulse and a time for supplying the driving pulse necessary to raise the temperature of the voltage generating unit from the temperature in the initial operation state to a temperature assumed under a series of analysis conditions. An initial driving condition calculating means for calculating, and in the initial stage of operation, the driving pulse having a relatively high frequency calculated by the initial driving condition calculating means is generated for a time calculated by the initial driving condition calculating means. Control means for controlling the pulse generating means;
An ion trap apparatus comprising: The ion trap apparatus according to claim 1 or 2,
The ion trap is a three-dimensional quadrupole ion trap composed of one ring electrode and a pair of end cap electrodes arranged opposite to each other with the ring electrode interposed therebetween, and the voltage generator is a rectangular wave voltage Is applied to the ring electrode.

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