Mass spectrometry apparatus and mass spectrometry method

Abstract

This mass spectrometer comprises: a quadrupole mass filter including first, second, third, and fourth rod electrodes; a first voltage application unit that applies first high-frequency alternating-current voltage to the first and second rod electrodes, and applies second high-frequency alternating-current voltage having a phase opposite to that of the first high-frequency alternating-current voltage to the third and fourth rod electrodes; and a control unit that, during an analysis operation, controls the first high-frequency alternating-current voltage to be applied to the first and second rod electrodes by the first voltage application unit, and controls the second high-frequency alternating-current voltage to be applied to the third and fourth rod electrodes by the first voltage application unit. The control unit controls the first voltage application unit before the analysis operation such that the first high-frequency alternating-current voltage corresponding to the mass of an object to be analyzed is applied to the first and second rod electrodes and the second high-frequency alternating-current voltage corresponding to the mass of the object to be analyzed is applied to the third and fourth rod electrodes by the first voltage application unit.

Description

[Technical field]

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

[0002] The quadrupole mass spectrometer includes a quadrupole filter formed of four rod electrodes (see, for example, Patent Document 1). A superimposed voltage of a DC voltage +U and a radio frequency voltage +V·cosωt is applied to one pair of the four rod electrodes, and a superimposed voltage of a DC voltage -U and a radio frequency voltage -V·cosωt is applied to the other pair of rod electrodes. Of the ions introduced into the quadrupole filter, only ions with a specific mass determined by the voltages U and V oscillate stably and pass through the quadrupole filter. The ions that have passed through the quadrupole filter are guided to a detector. A mass spectrum is then generated based on the mass-to-charge ratio (m / z) of the ions detected by the detector. [Patent Document 1] JP 2002-033075 A Summary of the Invention [Problem to be solved by the invention]

[0003] When a voltage is applied to the electrode rods, the electrode rods are deformed due to heat generation. This causes the dimensions of the space formed by the four rod electrodes to change depending on the magnitude of the applied voltage. In addition, the output voltage changes depending on the temperature characteristics of the components of the voltage generation circuit. This causes a change in the relationship between the mass-to-charge ratio of the ions passing through the quadrupole mass filter and the applied voltage. As a result, the accuracy of the analysis results may decrease.

[0004] An object of the present invention is to provide a mass spectrometer and a mass spectrometric method capable of improving the accuracy of the analysis results. [Means for solving the problem]

[0005] A mass spectrometer according to one embodiment includes a quadrupole mass filter including first, second, third, and fourth rod electrodes; a first voltage application unit that applies a first high frequency AC voltage to the first and second rod electrodes and applies a second high frequency AC voltage having an opposite phase to the first high frequency AC voltage to the third and fourth rod electrodes; and a control unit that controls the first high frequency AC voltage applied to the first and second rod electrodes by the first voltage application unit and controls the second high frequency AC voltage applied to the third and fourth rod electrodes by the first voltage application unit during an analytical operation, and the control unit controls the first voltage application unit such that the first high frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes and the second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes before the analytical operation. Effect of the Invention

[0006] According to the present invention, it is possible to improve the accuracy of the analysis results in a mass spectrometer and a mass analysis method. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a mass spectrometer according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the stability region of ions in a quadrupole mass filter. [Diagram 3] FIG. 3 is a flowchart showing the operation of the main control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A mass spectrometer according to an embodiment will be described in detail below with reference to the drawings.

[0009] (1) Mass spectrometer configuration 1 is a schematic diagram showing the configuration of a mass spectrometer according to one embodiment. The mass spectrometer 100 includes a mass analysis unit 10, a vacuum pump 20, an AC voltage generating circuit 30, a DC voltage generating circuit 40, a power supply circuit 50, a power switch 60, a display unit 70, an operation unit 80, and a main control device 90.

[0010] The mass analysis section 10 includes an ionization chamber 10a and an analysis chamber 10b. The analysis chamber 10b includes an ion lens 2, a quadrupole mass filter 3, and an ion detection section 4. For example, a liquid chromatograph (not shown) is connected to the ionization chamber 10a. A liquid sample to be measured is supplied to the ionization chamber 10a from the liquid chromatograph. In the ionization chamber 10a, the liquid sample is sprayed while being charged by, for example, an ESI probe (electrospray ionization probe) (not shown). As a result, the components in the liquid sample are ionized in the ionization chamber 10a. Usually, monovalent ions of each component are generated. The ions in the ionization chamber 10a are guided to the ion lens 2 of the analysis chamber 10b.

[0011] The analysis chamber 10b is maintained at a vacuum level (10 -2 ~10 -3 The ion lens 2 is maintained in a vacuum state of 100 Pa. The ions guided to the ion lens 2 are converged so as to fly parallel to the axis AX and pass through the ion lens 2.

[0012] The quadrupole mass filter 3 includes first to fourth rod electrodes 3a to 3d. The first rod electrode 3a and the third rod electrode 3b are arranged symmetrically with respect to the axis AX, and the third rod electrode 3c and the fourth rod electrode 3d are arranged symmetrically with respect to the axis AX. The first to fourth rod electrodes 3a to 3d are provided at equal angular intervals at positions spaced a distance r from the axis AX. This forms a cylindrical space SP surrounded by the first to fourth rod electrodes 3a to 3d. The space SP extends in the direction of the axis AX.

[0013] An AC voltage generating circuit 30 and a DC voltage generating circuit 40 are connected to the first to fourth rod electrodes 3a to 3d. The AC voltage generating circuit 30 and the DC voltage generating circuit 40 are connected to a power supply circuit 50. The power supply circuit 50 is connected to an external power supply and supplies power to the AC voltage generating circuit 30 and the DC voltage generating circuit 40. In this embodiment, the power supply circuit 50 also supplies power to various components of the mass spectrometer 100.

[0014] The AC voltage generating circuit 30 generates a high frequency AC voltage +V·cosωt (hereinafter referred to as a first high frequency AC voltage) and a high frequency AC voltage -V·cosωt (hereinafter referred to as a second high frequency AC voltage) based on the power supplied from the power supply circuit 50. Here, V is the amplitude (maximum value) of the first and second high frequency AC voltages, ω is the angular frequency (each frequency), and t is time. The first and second high frequency AC voltages have phases shifted by 180° from each other (opposite phases). The effective values ​​of the first and second high frequency AC voltages are expressed as V / √2.

[0015] The DC voltage generating circuit 40 generates a DC voltage +U (hereinafter referred to as a first DC voltage) and a DC voltage −U (hereinafter referred to as a second DC voltage), where U is the value of the first and second DC voltages.

[0016] The first and second rod electrodes 3a and 3b are applied with a first high-frequency AC voltage generated by the AC voltage generating circuit 30 and with a first DC voltage generated by the DC voltage generating circuit 40. On the other hand, the third and fourth rod electrodes 3c and 3d are applied with a second high-frequency AC voltage generated by the AC voltage generating circuit 30 and with a second DC voltage generated by the DC voltage generating circuit 40. As a result, a voltage +(U+V·cosωt) in which the first high-frequency AC voltage and the first DC voltage are superimposed is applied to the first and second rod electrodes 3a and 3b. Also, a voltage -(U+V·cosωt) in which the second high-frequency AC voltage and the second DC voltage are superimposed is applied to the third and fourth rod electrodes 3c and 3d. As a result, an electric field is formed in the space SP.

[0017] The power switch 60 is a switch for switching the power circuit 50 between the on state and the off state. In the present embodiment, the power switch 60 is switched by the user.

[0018] The ions that have passed through the ion lens 2 are guided to the space SP. The ions guided into the space SP vibrate in the space SP due to the electric field in the space SP. When the ions in the space SP vibrate unstably, the ions in the space SP cannot pass through the space SP of the quadrupole mass filter 3. Here, the ions in the space SP vibrate according to the following Mathieu equation (1).

[0019] [Number] K is a constant. The angular frequencies ω and the distance r of the first and second high-frequency alternating voltages are constant. In this case, according to the Mathieu equation, by setting the amplitudes V of the first and second high-frequency alternating voltages to specific values, ions having a specific mass-to-charge ratio m / z can be stably vibrated. In the quadrupole mass filter, the ions that vibrate stably can pass through the space SP. In the quadrupole mass filter, the ions that vibrate unstably cannot pass through the space SP.

[0020] Figure 2 is a diagram of the stable region of the ions of the quadrupole mass filter. The vertical axis in Figure 2 is the value U of the first and second DC voltages, and the horizontal axis is the value of the amplitude V of the first and second high-frequency alternating voltages ±(U + V·cosωt). In Figure 2, examples of the stable regions of the ions having masses m1, m2, and m3 are shown respectively. In this example, m1 < m2 < m3. Note that the stable region of the ions is shown by the solution of the Mathieu equation. In Figure 2, in the quadrupole mass filter 3, the stable regions R1, R2, and R3 of the ions having masses m1, m2, and m3 are shown respectively.

[0021] For example, when a point determined by the value of the amplitude V of the first and second radio frequency AC voltages and the value U of the first and second DC voltages is within the stability region R1, an ion of mass m1 can stably pass through the space SP of the quadrupole mass filter 3. Although three masses are shown in the example of Fig. 2, the stability region is also determined for ions of any other mass by the value of the amplitude V of the first and second radio frequency AC voltages and the value U of the first and second DC voltages. Thus, according to the ion stability region diagram, ions having a specific mass-to-charge ratio can be passed through the space SP of the quadrupole mass filter 3 by determining the value of the DC voltage U based on the amplitude V of the radio frequency AC voltage determined by the above formula (1).

[0022] During the analysis operation of the mass analysis operation of the mass spectrometer 100, the main controller 90 changes the amplitude V of the first and second high frequency AC voltages and the value U of the first and second DC voltages according to a scan line SL that passes through non-overlapping parts of the regions R1, R2, and R3. In this case, the ratio of the amplitude V of the first and second high frequency AC voltages to the value U of the first and second DC voltages on the scan line SL is kept constant. As a result, ions of masses m1, m2, and m3 pass through the quadrupole mass filter in response to the changes in the amplitude V of the high frequency AC voltage and the DC voltage U.

[0023] 1, ions that have passed through a space SP of a quadrupole mass filter 3 are detected by an ion detection unit 4. The ion detection unit 4 is, for example, a secondary electron multiplier. A mass spectrum is created based on an output signal from the ion detection unit 4. A display unit 70 displays various information related to the mass spectrometer 100. An operation unit 80 is used for various operations of the mass spectrometer 100.

[0024] Here, when a voltage is applied to the first to fourth rod electrodes 3a to 3d while the temperatures of the first to fourth rod electrodes 3a to 3d are low, the first to fourth rod electrodes 3a to 3d may heat up and thermally expand. In this case, the first to fourth rod electrodes 3a to 3d are deformed, and the value of the distance r in the space SP of the quadrupole mass filter 3 changes. Therefore, in the above formula (1), the relationship between the value of the mass-to-charge ratio (m / z) and the amplitude V of the first and second high-frequency AC voltages changes. In this case, a deviation occurs in the mass-to-charge ratio (m / z) of the mass spectrum generated based on the output signal of the ion detection unit 4.

[0025] Furthermore, when the AC voltage generating circuit 30 outputs the first and second high frequency AC voltages while the temperature of the AC voltage generating circuit 30 is low, the amplitude V of the first and second high frequency AC voltages and the value U of the first and second DC voltages may vary due to the temperature characteristics of components such as ICs (integrated circuits) that make up the AC voltage generating circuit 30 and the DC voltage generating circuit 40. In this case, a deviation in the mass-to-charge ratio (m / z) of the mass spectrum occurs due to a deviation in the applied voltage.

[0026] Therefore, in the mass spectrometer 100, before an analysis operation is started, a first high-frequency AC voltage and a first DC voltage are applied to the first and second rod electrodes 3a, 3b, and a second high-frequency AC voltage and a second DC voltage are applied to the third and fourth rod electrodes 3c, 3d by the AC voltage generating circuit 30 and the DC voltage generating circuit 40. This allows the first to fourth rod electrodes 3a to 3d, the AC voltage generating circuit 30, and the DC voltage generating circuit 40 to be pre-warmed. Hereinafter, the operation of applying voltages to the first to fourth rod electrodes 3a to 3d before an analysis operation is referred to as a warm-up operation.

[0027] On the other hand, in the above formula (1), the mass-to-charge ratio (m / z) of the ions and the amplitude V of the high-frequency AC voltage are in a proportional relationship. Therefore, in order to pass ions having a relatively large mass through the space SP of the quadrupole mass filter 3, it is necessary to increase the amplitude V of the high-frequency AC voltage. In that case, the temperature of the first to fourth rod electrodes 3a to 3d during the analysis operation becomes higher than the temperature of the first to fourth rod electrodes 3a to 3d due to the warm-up operation. This may cause a deviation in the mass-to-charge ratio (m / z) of the mass spectrum.

[0028] Therefore, the present inventors have studied appropriate voltage values ​​to be applied to the first to fourth rod electrodes 3a to 3d in the warm-up operation in order to suppress deviations in the mass-to-charge ratio of the mass spectrum. As a result of the inventors' studies, it has been found that the occurrence of deviations in the mass-to-charge ratio of the mass spectrum during the analysis operation can be suppressed by applying a first high-frequency AC voltage corresponding to the mass of the analysis target to the first and second rod electrodes 3a and 3b and a second high-frequency AC voltage corresponding to the mass of the analysis target to the third and fourth rod electrodes 3c and 3d in the warm-up operation.

[0029] Here, the first high frequency AC voltage corresponding to the mass of the analysis target is the effective value of the high frequency AC voltage +(U+V·cosωt) applied to the first and second rod electrodes 3a, 3b during the analysis operation when the ions to be analyzed pass through the space SP of the quadrupole mass filter 3. Moreover, the second high frequency AC voltage corresponding to the mass of the analysis target is the effective value of the high frequency AC voltage -(U+V·cosωt) applied to the third and fourth rod electrodes 3a, 3b during the analysis operation when the ions to be analyzed pass through the space SP of the quadrupole mass filter 3.

[0030] In this case, the effective values ​​of the radio frequency AC voltages applied to the first and second rod electrodes 3a, 3b are changed so that a peak corresponding to the analyte appears in the mass spectrum when the analyte ions pass through the space SP of the quadrupole mass filter 3 during the analysis operation. The first and second radio frequency AC voltages corresponding to the mass of the analyte may be any value within the range of the effective value of the radio frequency AC voltage changed when the analyte ions pass through the space SP of the quadrupole mass filter 3.

[0031] Therefore, in the mass spectrometer 100 according to this embodiment, during the warm-up operation, a first high-frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes 3a, 3b, and a second high-frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes 3c, 3d.

[0032] When the analysis target contains a plurality of substances having a plurality of different substances (components), during the warm-up operation, a first high-frequency AC voltage corresponding to the highest mass among the plurality of substances is applied to the first and second rod electrodes 3a, 3b by the AC voltage generating circuit 30, and a second high-frequency AC voltage corresponding to the highest mass among the plurality of substances is applied to the third and fourth rod electrodes.

[0033] In this embodiment, the first high-frequency AC voltage applied to the first and second rod electrodes 3a, 3b during the warm-up operation is equal to the second high-frequency AC voltage applied to the third and fourth rod electrodes 3c, 3d. Hereinafter, the effective values ​​of the first and second high-frequency AC voltages applied to the first to fourth rod electrodes 3a-3d during the warm-up operation are referred to as the warm-up effective value Vw.

[0034] In the mass spectrometer 100 according to this embodiment, the warm-up effective value Vw varies depending on the highest mass of one or more substances contained in the analysis target. Note that the warm-up effective value Vw is not limited to a certain value, and may be a value within a certain range including the effective value of the first high frequency AC voltage that corresponds to the mass of the analysis target.

[0035] Here, the maximum effective value of the first and second high-frequency AC voltages that can be applied to the first and second rod electrodes 3a, 3b by the AC voltage generating circuit 30 is referred to as the maximum effective value Vemax. When the analysis target contains a substance having a relatively high mass, the warm-up effective value Vw is set, for example, by the AC voltage generating circuit 30 to an effective value that is 50% or more of the maximum effective value Vemax. When the analysis target contains a substance having a relatively low mass, the warm-up effective value Vw is set, for example, by the AC voltage generating circuit 30 to an effective value that is lower than 50% of the maximum effective value Vemax.

[0036] (2) Configuration and Operation of Main Control Unit 90 The main control device 90 includes an operation command unit 91, an AC voltage determination unit 92, a DC voltage determination unit 93, and a voltage control unit 94 as functional components. In this embodiment, the components (91-94) are realized by hardware such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a storage device, and software such as a program. In this case, a warm-up operation control program is stored in the ROM or the storage device. The functions of the components (91-94) are realized by the CPU executing the warm-up operation control program stored in the ROM on the RAM.

[0037] 3 is a flowchart showing the operation of the main control device 90. First, the operation command unit 91 determines whether the power switch 60 is turned on or not (step S1). If the power switch 60 is turned on, the operation command unit 91 turns on the vacuum pump 20 (step S2). This keeps the ionization chamber 10a and the analysis chamber 10b in a vacuum state. The operation command unit 91 also turns on the power supply circuit 50.

[0038] The AC voltage determination unit 92 determines the warm-up effective value Vw of the first and second high-frequency AC voltages to be generated by the AC voltage generation circuit 30 in the warm-up operation (step S3). In this embodiment, when the analysis target is predetermined, the AC voltage determination unit 92 may determine the warm-up effective value Vw to a predetermined value, or may determine the warm-up effective value Vw based on the maximum mass (mass-to-charge ratio) of the masses of a plurality of substances contained in the analysis target input by the user using the operation unit 80. Note that when the warm-up effective value Vw is predetermined (i.e., when the analysis target is predetermined and the maximum mass of one or more substances contained in the analysis target is known), the AC voltage determination unit 92 may not be provided. In this case, the warm-up effective value Vw is described in the warm-up operation control program. In FIG. 2, the amplitude V for obtaining the warm-up effective value Vw is shown as the warm-up amplitude VW (=√2·Vw).

[0039] Here, a small amount of ions may remain in the ionization chamber 10a or the analysis chamber 10b. In this case, if the remaining ions pass through the space SP and enter the ion detection unit 4, deterioration of the ion detection unit 4 may progress during the warm-up operation. Therefore, in this embodiment, a DC voltage is applied to the first to fourth rod electrodes 3a to 3d during the warm-up operation so that the remaining ions do not pass through the space SP. Hereinafter, the values ​​of the first and second DC voltages for preventing the ions from passing through the space SP are referred to as a blocking voltage value Up.

[0040] The DC voltage determination unit 93 determines blocking voltage values ​​Up of the first and second DC voltages to be generated by the DC voltage generation circuit 40 in the warm-up operation (step S4). In this embodiment, the DC voltage determination unit 93 determines the blocking voltage values ​​Up of the first and second DC voltages such that the ratio between the warm-up amplitude VW corresponding to the warm-up effective value Vw of the first and second high-frequency AC voltages determined in step S3 and the values ​​of the first and second DC voltages is a value at which ions do not pass through the space SP of the quadrupole mass filter 3. Specifically, in FIG. 2, the DC voltage determination unit 93 determines the blocking voltage values ​​Up of the first and second DC voltages such that a point determined by the amplitude VW corresponding to the warm-up effective value Vw of the first and second high-frequency AC voltages and the values ​​U of the first and second DC voltages does not exist in any stable region. Hereinafter, the first and second high frequency AC voltages having the warm-up effective value Vw and the first and second DC voltages having the blocking voltage value Up will be referred to as warm-up voltages.

[0041] The voltage control unit 94 commands the AC voltage generating circuit 30 and the DC voltage generating circuit 40 to apply a warm-up voltage (step S5). As a result, a first high-frequency AC voltage having the warm-up effective value Vw determined by the AC voltage determining unit 92 is applied by the AC voltage generating circuit 30 to the first and second rod electrodes 3a, 3b, and a second high-frequency AC voltage having the warm-up effective value Vw determined by the AC voltage determining unit 92 is applied to the third and fourth rod electrodes 3c, 3d.

[0042] Moreover, a first DC voltage having a blocking voltage value Up determined by the DC voltage determination unit 93 is applied to the first and second rod electrodes 3a, 3b, and a second DC voltage having a blocking voltage value Up is applied to the third and fourth rod electrodes 3c, 3d. The application of the warm-up effective value Vw and the blocking voltage value Up to the first to fourth rod electrodes 3a to 3d constitutes a warm-up operation.

[0043] The voltage control unit 94 determines whether a predetermined time (hereinafter referred to as the warm-up time) has elapsed since the start of the warm-up operation (step S6). If the warm-up time has not elapsed, the warm-up operation continues. If the warm-up time has elapsed, the voltage control unit 94 causes the display unit 70 to display that the warm-up time has elapsed and that the mass spectrometer 100 is ready to perform an analysis operation (step S7).

[0044] The operation command unit 91 determines whether or not the user has issued a command to start the analysis operation using the operation unit 80 (step S8). If the user has not issued a command to start the analysis operation, the process of step S7 is continued. At this time, the warm-up operation is also continued.

[0045] When the user issues a command to start the analysis operation using the operation unit 80, the voltage control unit 94 ends the warm-up operation (step S9). In this state, the analysis operation of the mass spectrometer 100 starts (step S10). During the analysis operation of the mass spectrometer 100, the voltage control unit 94 controls the amplitude V of the first and second high-frequency AC voltages and the value U of the first and second DC voltages based on the scanning line SL in FIG. 2. The voltage control unit 94 determines whether the analysis operation has ended (step S11). If the analysis operation has not ended, the analysis operation continues. If the analysis operation has ended, the operation command unit 91 determines whether the power switch 60 has been turned off (step S12). If the power switch 60 has not been turned off, the operation command unit 91 returns to step S5. This starts the warm-up operation. In this case, the warm-up operation is performed between one analysis operation and the next analysis operation. If the power switch 60 is turned off in step S12, the warm-up operation ends.

[0046] (3) Effects of the embodiment In this embodiment, the temperature of the first to fourth rod electrodes 3a to 3d is increased in advance during the warm-up operation by application of the first and second high-frequency AC voltages having the warm-up effective value Vw. As a result, the dimensions or shapes of the first to fourth rod electrodes 3a to 3d are changed from those in a state in which no voltage is applied to the first to fourth rod electrodes 3a to 3d. In this case, the warm-up effective value Vw is set by the AC voltage generating circuit 30 so as to correspond to the highest mass of one or more substances contained in the analysis target. As a result, the temperatures of the first to fourth rod electrodes 3a to 3d are increased to a temperature that is almost equal to or close to the temperature during the analysis operation. Therefore, during the analysis operation, the change in the dimensions or shape of the first to fourth rod electrodes 3a to 3d is small, and the change in the distance r from the axis AX of the quadrupole mass filter 3 to the first to fourth rod electrodes 3a to 3d is small. This suppresses changes in the relationship between the voltages applied to the first to fourth rod electrodes 3a to 3d and the mass-to-charge ratio of the ions passing through the quadrupole mass filter 3.

[0047] In contrast, if the effective values ​​of the first and second high frequency AC voltages applied to the first to fourth rod electrodes 3a to 3d during the warm-up operation are set to values ​​lower than the effective values ​​applied during the analysis operation (for example, values ​​lower than the value corresponding to the lowest mass of one or more substances contained in the analysis target), the dimensions and shapes of the first to fourth rod electrodes 3a to 3d change significantly when the voltage applied to the first to fourth rod electrodes 3a to 3d increases during the analysis operation. As a result, the change in the distance r from the spatial SP axis AX of the quadrupole mass filter 3 to the first to fourth rod electrodes 3a to 3d is large.

[0048] In addition, in this embodiment, during the warm-up operation, the AC voltage generating circuit 30 outputs the first and second high-frequency AC voltages having the warm-up effective value Vw corresponding to the highest mass of one or more substances contained in the analysis target, so that the temperatures of the components of the AC voltage generating circuit 30 are preliminarily increased. In this case, the deviation of the change in the output voltage due to the temperature characteristics of the components increases as the temperature increases. In this embodiment, the temperatures of the components are preliminarily increased, so that the change in the first and second high-frequency AC voltages due to the change in temperature is suppressed.

[0049] As a result, during an analytical operation, deviations in the mass-to-charge ratio of ions passing through the quadrupole mass filter 3 are suppressed, thereby improving the accuracy of the analytical results.

[0050] In addition, in this embodiment, when the first high frequency AC voltage with the warm-up effective value Vw is applied to the first and second rod electrodes and the second high frequency AC voltage with the warm-up effective value Vw is applied to the third and fourth rod electrodes before the analysis operation, the first DC voltage with the blocking voltage value Up is applied to the first and second rod electrodes 3a and 3b and the second DC voltage with the blocking voltage value Up is applied to the third and fourth rod electrodes 3c and 3d. This prevents ions remaining in the ionization chamber 10a or the analysis chamber 10b from passing through the space SP. As a result, it is possible to suppress deterioration of the ion detection unit 4 provided in the rear stage of the quadrupole mass filter 3. In addition, since the temperature of the components of the DC voltage generation circuit 40 is increased in advance by the output of the first and second DC voltages with the blocking voltage value Up, the change in the output voltage of the DC voltage generation circuit 40 due to the temperature characteristics of the components is small. Therefore, it is possible to output the blocking voltage value Up more accurately during the analysis operation.

[0051] Furthermore, the first to fourth rod electrodes 3a to 3d are kept at a relatively high temperature during the period from when the power supply circuit 50 is turned on until the start of an analysis operation. As a result, at the time of the first analysis operation after the power supply circuit 50 is started, the temperatures of the first to fourth rod electrodes 3a to 3d have already risen, so that changes in the dimensions or shapes of the first to fourth rod electrodes 3a to 3d are suppressed.

[0052] Furthermore, the first to fourth rod electrodes 3a to 3d are kept at a relatively high temperature during the period from the end of one analysis operation to the start of a second analysis operation. As a result, the temperatures of the first to fourth rod electrodes 3a to 3d are already elevated during the next analysis operation, so that changes in the dimensions or shapes of the first to fourth rod electrodes 3a to 3d are suppressed. Therefore, the accuracy of the analysis results is improved even when multiple analysis operations are performed.

[0053] (4) Other embodiments In the above embodiment, when the warm-up time has elapsed, the display unit 70 displays that the mass spectrometer 100 is capable of performing an analytical operation. Alternatively, the user may be notified that an analytical operation is capable of being performed by lighting a lamp or the like, or the user may be notified that an analytical operation is capable of being performed by audio.

[0054] (5) Correspondence between each component of the claims and each part of the embodiment An example of the correspondence between each component of the claims and each element of the embodiment will be described below. In the above embodiment, the AC voltage generating circuit 30 is an example of a first voltage applying unit, the DC voltage generating circuit 40 is an example of a second voltage applying unit, the main control device 90 is an example of a control unit, the voltage control unit 94 is an example of a determination unit, and the display unit 70 is an example of a notification unit.

[0055] (6) Description It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0056] (Item 1) A mass spectrometer according to one embodiment includes a quadrupole mass filter including first, second, third, and fourth rod electrodes; a first voltage application unit that applies a first high frequency AC voltage to the first and second rod electrodes and applies a second high frequency AC voltage having an opposite phase to the first high frequency AC voltage to the third and fourth rod electrodes; and a control unit that controls the first high frequency AC voltage applied to the first and second rod electrodes by the first voltage application unit and controls the second high frequency AC voltage applied to the third and fourth rod electrodes by the first voltage application unit during an analytical operation, and the control unit controls the first voltage application unit such that the first high frequency AC voltage corresponding to the mass of an analysis target is applied to the first and second rod electrodes by the first voltage application unit and the second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes by the first voltage application unit before the analytical operation.

[0057] In a mass spectrometer according to one aspect, a first high frequency AC voltage corresponding to the mass of an analysis target is applied to the first and second rod electrodes before an analysis operation. A second high frequency AC voltage corresponding to the mass of an analysis target is applied to the third and fourth rod electrodes. As a result, the first to fourth rod electrodes generate heat before the analysis operation. Also, the temperature of components of the first voltage application unit increases.

[0058] During an analysis operation, the first high frequency AC voltage is controlled and the second high frequency AC voltage is controlled, whereby ions having a mass-to-charge ratio according to the first and second high frequency AC voltages pass through the quadrupole mass filter.

[0059] In this case, if the dimensions or shapes of the first to fourth rod electrodes change due to a change in the temperature of the first to fourth rod electrodes, a deviation occurs in the relationship between the mass-to-charge ratio of the ions passing through the quadrupole mass filter and the first and second high-frequency AC voltages. Also, if the temperature of the components of the first voltage application unit changes, the first and second high-frequency AC voltages change due to the temperature characteristics of the components.

[0060] According to the above configuration, the temperature of the first to fourth rod electrodes is raised in advance by application of the first and second high frequency AC voltages corresponding to the mass of the analysis target, so that the change in the size or shape of the first to fourth rod electrodes is small. Also, the temperature of the components of the first voltage application unit is raised in advance by output of the first and second high frequency AC voltages corresponding to the mass of the analysis target, so that the change in the output voltage of the first voltage application unit due to the temperature characteristics of the components is small. Therefore, during the analysis operation, the deviation in the mass-to-charge ratio (m / z) of the ions passing through the quadrupole mass filter is suppressed. As a result, the accuracy of the analysis result is improved.

[0061] (Clause 2) In the mass spectrometer described in paragraph 1, when the analysis target includes a plurality of substances having different masses, the control unit may control the first voltage application unit so that, before the analysis operation, a first high-frequency AC voltage corresponding to the highest mass among the plurality of substances is applied to the first and second rod electrodes and a second high-frequency AC voltage corresponding to the highest mass among the plurality of substances is applied to the third and fourth rod electrodes.

[0062] According to the mass spectrometer described in paragraph 2, even when the analysis target contains a plurality of substances having different masses, the first to fourth rod electrodes undergo small changes in size or shape during analysis, and the output voltage of the first voltage application unit undergoes small changes due to the temperature characteristics of the components. Therefore, deviations in the mass-to-charge ratio (m / z) of ions passing through the quadrupole mass filter during analysis are suppressed. As a result, the accuracy of the analysis results is improved.

[0063] (Item 3) The mass spectrometer described in item 1 or 2 may further include a second voltage application unit that applies a first DC voltage to the first and second rod electrodes and applies a second DC voltage having a polarity opposite to that of the first DC voltage to the third and fourth rod electrodes, and the control unit may control the first DC voltage applied to the first and second rod electrodes and the second DC voltage applied to the third and fourth rod electrodes by the second voltage application unit during the analysis operation, and control the second voltage application unit such that, before the analysis operation, the first DC voltage having a value at which ions do not pass through a space surrounded by the first, second, third and fourth rod electrodes is applied to the first and second rod electrodes and the second DC voltage having a value at which ions do not pass through the space is applied to the third and fourth rod electrodes.

[0064] According to the mass spectrometer described in the third aspect, when a first high-frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes and a second high-frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes before an analysis operation, ions remaining in the space surrounded by the first to fourth rod electrodes are prevented from passing through the space, which makes it possible to suppress deterioration of the detector provided after the quadrupole filter.

[0065] In addition, since the temperature of the components of the second voltage application unit is raised in advance by the output of the first and second DC voltages, the change in output voltage of the second voltage application unit due to the temperature characteristics of the components is small, which makes it possible to pass ions more accurately during analysis.

[0066] (Item 4) In the mass spectrometer described in item 3, the control unit may control the second voltage application unit so that the ratio between the value of the first DC voltage and the amplitude of the first high frequency AC voltage and the ratio between the value of the second DC voltage and the amplitude of the second high frequency AC voltage become values ​​that prevent ions from passing through the space surrounded by the first, second, third and fourth rod electrodes.

[0067] According to the mass spectrometer described in paragraph 4, the first to fourth rod electrodes are kept at a relatively high temperature during the period from start-up of the power supply circuit to before the start of an analytical operation. As a result, at the time of the first analytical operation after start-up of the power supply circuit, the temperatures of the first to fourth rod electrodes have already risen, so that changes in the dimensions or shapes of the first to fourth rod electrodes are small.

[0068] (Item 5) The mass spectrometer described in any one of items 1 to 4 may further include a power supply circuit that supplies power to the first voltage application unit, and the control unit may control the first voltage application unit so that, from the time the power supply circuit is started up until the start of an analytical operation, a first high frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes and a second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes.

[0069] According to the mass spectrometer described in paragraph 5, the first to fourth rod electrodes are kept at a relatively high temperature during the period from the end of one analysis operation to the start of a second analysis operation. As a result, in the next analysis operation, the temperatures of the first to fourth rod electrodes are already elevated, so that changes in the dimensions or shapes of the first to fourth rod electrodes are small. Therefore, the accuracy of the analysis results is improved even when multiple analysis operations are performed.

[0070] (Item 6) In the mass spectrometer described in any one of items 1 to 5, the first control unit may control the first voltage application unit so that, between one analysis operation and a next analysis operation, a first high frequency AC voltage corresponding to a mass of the analysis target is applied to the first and second rod electrodes and a second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes.

[0071] According to the mass spectrometer described in item 6, it is possible to suppress deviations in the mass-to-charge ratio of ions passing through the quadrupole mass filter through simple control, and also to suppress deterioration of the detector.

[0072] (Item 7) The mass spectrometer according to any one of items 1 to 6 may further include a determination unit that determines whether a predetermined warm-up time has elapsed in a state in which a first high frequency AC voltage corresponding to a mass of an analysis target is applied to the first and second rod electrodes and a second high frequency AC voltage corresponding to a mass of an analysis target is applied to the third and fourth rod electrodes, and a notification unit that notifies that the warm-up time has elapsed by the determination unit.

[0073] According to the mass spectrometer described in paragraph 7, the user can easily know whether or not the warm-up operation that enables the obtaining of highly accurate analytical results has been completed.

[0074] (Item 8) A mass spectrometry method according to another aspect is a mass spectrometry method using a mass spectrometer having a quadrupole mass filter including first, second, third and fourth rod electrodes, and includes the steps of controlling a first high frequency AC voltage applied to the first and second rod electrodes and controlling a second high frequency AC voltage applied to the third and fourth rod electrodes during an analytical operation, and applying a first high frequency AC voltage corresponding to the mass of the analysis target to the first and second rod electrodes and applying a second high frequency AC voltage corresponding to the mass of the analysis target to the third and fourth rod electrodes before the analytical operation.

[0075] According to another aspect of the mass analysis method, the temperatures of the first to fourth rod electrodes are raised in advance by applying the first and second high-frequency AC voltages corresponding to the masses of the objects to be analyzed, so that there is little change in the dimensions or shapes of the first to fourth rod electrodes. Therefore, during the analysis operation, deviations in the mass-to-charge ratio (m / z) of ions passing through the quadrupole mass filter are suppressed. As a result, the accuracy of the analysis results is improved.

Claims

1. a quadrupole mass filter including first, second, third and fourth rod electrodes; a first voltage application unit that applies a first high frequency AC voltage to the first and second rod electrodes and applies a second high frequency AC voltage having a phase opposite to that of the first high frequency AC voltage to the third and fourth rod electrodes; a control unit that controls the first high frequency AC voltage applied to the first and second rod electrodes by the first voltage application unit during an analysis operation, and controls the second high frequency AC voltage applied to the third and fourth rod electrodes by the first voltage application unit, the control unit controls the first voltage application unit so that, before the analysis operation, the first high frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes by the first voltage application unit and the second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes by the first voltage application unit as a warm-up operation, and controls the first voltage application unit so that the analysis operation is performed following the warm-up operation.

2. 2. The mass spectrometer according to claim 1, wherein, when the analysis target includes a plurality of substances having different masses, the control unit controls the first voltage application unit so that, before the analysis operation, the first high frequency AC voltage corresponding to the highest mass among the plurality of substances is applied to the first and second rod electrodes and the second high frequency AC voltage corresponding to the highest mass among the plurality of substances is applied to the third and fourth rod electrodes.

3. a second voltage application unit that applies a first DC voltage to the first and second rod electrodes and applies a second DC voltage having a polarity opposite to that of the first DC voltage to the third and fourth rod electrodes; 3. The mass spectrometer according to claim 1, wherein the control unit controls the first DC voltage applied to the first and second rod electrodes and the second DC voltage applied to the third and fourth rod electrodes by the second voltage application unit during the analysis operation, and controls the second voltage application unit before the analysis operation so that the first DC voltage having a value that prevents ions from passing through a space surrounded by the first, second, third, and fourth rod electrodes is applied to the first and second rod electrodes and the second DC voltage having a value that prevents ions from passing through the space is applied to the third and fourth rod electrodes.

4. 4. The mass spectrometer according to claim 3, wherein the control unit controls the second voltage application unit so that a ratio between a value of the first DC voltage and an amplitude of the first high frequency AC voltage and a ratio between a value of the second DC voltage and an amplitude of the second high frequency AC voltage are values ​​that prevent ions from passing through the space surrounded by the first, second, third, and fourth rod electrodes.

5. Further comprising a power supply circuit that supplies power to the first voltage application unit, 3. The mass spectrometer according to claim 1, wherein the control unit controls the first voltage application unit so that, from the time when the power supply circuit is started until the start of the analysis operation, the first high frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes and the second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes.

6. 3. The mass spectrometer according to claim 1, wherein the control unit controls the first voltage application unit so that, between one analytical operation and a next analytical operation, the first high frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes and the second high frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes.

7. a determination unit that determines whether a predetermined warm-up time has elapsed in a state in which the first high-frequency AC voltage corresponding to the mass of the analysis target is applied to the first and second rod electrodes and the second high-frequency AC voltage corresponding to the mass of the analysis target is applied to the third and fourth rod electrodes; 3. The mass spectrometer according to claim 1, further comprising a notification unit that notifies the user that the warm-up time has elapsed by the determination unit.

8. A mass spectrometry method using a mass spectrometer having a quadrupole mass filter including first, second, third and fourth rod electrodes, comprising: controlling a first high frequency AC voltage applied to the first and second rod electrodes and controlling a second high frequency AC voltage applied to the third and fourth rod electrodes during an analysis operation; a step of applying the first high frequency AC voltage corresponding to a mass of an analysis target to the first and second rod electrodes and applying the second high frequency AC voltage corresponding to a mass of the analysis target to the third and fourth rod electrodes as a warm-up operation before the analysis operation; and performing the analysis operation following the warm-up operation.

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