Mass spectrometer

Abstract

A mass spectrometer simplifies the configuration of a power supply device that drives a linear ion trap and performs mass scanning that discharges in the axial direction. The present invention is provided with: a linear ion trap part (2) comprising a plurality of rod electrodes (20) surrounding a central axis (C), an auxiliary electrode (21) provided on the outside of an ion emission-side end or protruding from the end and surrounding or sandwiching the central axis, and a lead-out electrode (23) disposed further on the outside of the auxiliary electrode; an RF voltage generation unit (50) that applies an RF voltage to the plurality of rod electrodes and the auxiliary electrode so as to form an RF electric field in an ion capture space surrounded by the plurality of rod electrodes and the auxiliary electrode; a lead-out voltage generation unit (52) that applies a DC voltage to the lead-out electrode so that a DC electric field for ion lead-out reaches the ion capture space; and a control unit (4) that controls the RF voltage generation unit and the extraction voltage generation unit, changes at least one of the RF voltage and the DC voltage in a state in which the ions are confined in the ion capture space, and discharges the ions in a direction along the central axis according to m / z.

Description

Technical Field

[0001] The present invention relates to a mass analyzer. Background Art

[0002] Conventionally, a mass analyzer using an ion trap that spatially confines ions by the action of an electric field has been known. In such an ion trap, it is roughly classified into a linear ion trap and a three-dimensional quadrupole ion trap (also called a Paul trap). The linear ion trap has advantages such as a relatively simple electrode shape and easy manufacturing, a large capacity of the ion capture space, and the ability to hold a larger amount of ions compared to the three-dimensional quadrupole ion trap.

[0003] In an ion trap, not only can ions be held, but it also has a mass separation (or mass screening) function of separating the held ions according to the mass-to-charge ratio (m / z) and discharging them to the outside of the trap. When performing mass separation in an ion trap, resonance excitation ejection is usually used (see Patent Document 1, etc.). In resonance excitation ejection in a linear ion trap, in addition to applying an RF voltage for confining ions in the ion capture space to each rod electrode, an alternating current (AC) voltage for ion excitation that resonates ions having a specific m / z is also applied to a specific rod electrode. As a result, among various ions captured in the ion capture space by the action of the RF electric field, only ions having the specific m / z vibrate selectively and significantly, and are discharged to the outside through an opening formed in the rod electrode.

[0004] The mass analyzer described in Patent Document 1 is an orthogonal ejection type linear ion trap that ejects ions held in a linear ion trap in a direction orthogonal to the ion optical axis (central axis) of the linear ion trap. However, as described in Patent Document 2, an axial ejection type linear ion trap that ejects ions in the same direction as the ion optical axis, that is, axially, using resonance excitation ejection is also known. The axial ejection type linear ion trap, for example, can make the ion optical axis of the linear ion trap and the ion optical axes of ion optical elements such as a multipole ion guide and a mass filter arranged in the subsequent stage coaxial, and thus has advantages such as easy arrangement of such ion optical elements.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-73703

[0008] Patent Document 2: International Publication No. 2023 / 203620

[0009] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2020-35726

[0010] Patent Document 4: International Publication No. 2020 / 129199 Summary of the Invention

[0011] Technical Problem to be Solved by the Invention

[0012] In resonance excitation ejection, mass separation of ions can be achieved with relatively high mass resolution. However, in resonance excitation ejection, in addition to the RF voltage, an AC voltage for ion excitation needs to be applied to the rod electrodes. Therefore, for example, as described in Patent Document 3, the configuration of the power supply device for applying voltage to the rod electrodes is complex. As a result, there are problems such as the device becoming large-sized and heavy, and the cost of the power supply becoming high.

[0013] The present invention is made to solve such a technical problem, and one of its purposes is to provide a mass spectrometry apparatus equipped with a linear ion trap that can simplify the configuration of the power supply device and can perform axial ejection while performing mass scanning.

[0014] Solution for Solving the Above Technical Problem

[0015] One solution of the mass spectrometry apparatus of the present invention completed to solve the above technical problem includes:

[0016] A linear ion trap section including a plurality of rod electrodes, auxiliary electrodes, and extraction electrodes, wherein the plurality of rod electrodes are arranged so as to surround a central axis, the auxiliary electrodes are provided outside or protrude from an outer end portion on the ion ejection side of one of the plurality of rod electrodes and surround or sandwich the central axis, and the extraction electrodes are arranged further outside the auxiliary electrodes;

[0017] An RF voltage generation section that applies an RF voltage to the plurality of rod electrodes and the auxiliary electrodes in order to form an RF electric field in an ion capture space surrounded by the plurality of rod electrodes and the auxiliary electrodes;

[0018] An extraction voltage generation section that applies a DC voltage to the extraction electrodes so that a DC electric field for extracting ions reaches the ion capture space; and

[0019] A control section that is a control section for controlling the RF voltage generation section and the extraction voltage generation section, and changes at least one of the RF voltage or the DC voltage in a state where ions are confined in the ion capture space, thereby discharging the ions from the ion capture space in a direction along the central axis according to the mass-to-charge ratio.

[0020] Advantages of the Invention

[0021] In the above-described aspect of the mass analysis device of the present invention, it is not necessary to superimpose and apply two different alternating voltages, namely an RF voltage and an AC voltage, to the rod electrodes as in the case of resonance excitation ejection. Therefore, according to the above-described aspect of the mass analysis device of the present invention, it is possible to achieve a mass scan in which ions are axially ejected from the linear ion trap in the order of mass-to-charge ratio, and the configuration of the power supply device for driving the linear ion trap can be simplified. As a result, the power supply device can be made smaller and lighter, and its cost can also be suppressed. In addition, since the ions are ejected axially from the linear ion trap, when ion optical elements such as a quadrupole mass filter and a multipole ion guide are arranged at the subsequent stage, the ion optical axes of the two can be made coaxial, and the arrangement of the ion optical elements becomes easier. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic perspective view showing the structure of the rod electrodes of an embodiment of the linear ion trap used in the mass analysis device of the present invention.

[0023] Figure 2 is Figure 1 an explanatory view of the structure of the rod electrodes shown.

[0024] Figure 3 are a schematic front longitudinal sectional view (A), a view seen from the line A - AA (B), and a view seen from the line B - BB (C) of the linear ion trap in the present embodiment.

[0025] Figure 4 is a Figure 3 schematic configuration diagram of a mass analysis device using the linear ion trap shown.

[0026] Figure 5 is a diagram showing an example of the simulation result of the ion orbit in the linear ion trap of the present embodiment.

[0027] Figure 6 is a timing chart showing an example of the change in the applied voltage when driving the linear ion trap (in the case where the RF voltage is changed).

[0028] Figure 7 is a timing chart showing another example of the change in the applied voltage when driving the linear ion trap (in the case where the extraction DC voltage is changed).

[0029] Figure 8 is a diagram showing an example of the calculation result of the relationship between the RF voltage and the ion extraction efficiency in the linear ion trap of the present embodiment.

[0030] Figure 9 is a diagram showing an example of the calculation result of the relationship between the m / z value of the ions and the ion extraction efficiency in the linear ion trap of the present embodiment.

[0031] Figure 10 FIG. is a diagram showing a configuration example of a mass spectrometer using the linear ion trap of the present embodiment.

[0032] Figure 11 is Figure 10 an example of a timing chart in the mass spectrometer shown.

[0033] Figure 12 FIG. is a diagram showing another configuration example of a mass spectrometer using the linear ion trap of the present embodiment.

[0034] Figure 13 FIG. is a diagram showing still another configuration example of a mass spectrometer using the linear ion trap of the present embodiment.

[0035] Figure 14 FIG. is a schematic front longitudinal sectional view showing another example of a linear ion trap.

[0036] Figure 15 FIG. is a schematic front longitudinal sectional view showing still another example of a linear ion trap.

[0037] Figure 16 is showing the drive Figure 15 an example of a timing chart showing a change in the applied voltage when the linear ion trap shown is driven.

[0038] Figure 17 FIG. is a diagram showing an example of a simulation result of an ion orbit in still another example of a linear ion trap. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, embodiments of the mass spectrometer of the present invention and the linear ion trap used therein will be described in detail with reference to the drawings.

[0040] [Schematic Configuration of Mass Spectrometer]

[0041] Figure 4 FIG. is a schematic configuration diagram of an example of the mass spectrometer of the present invention. For ease of explanation, in Figure 4 this figure and other figures, three mutually orthogonal X, Y, and Z axes are defined in space.

[0042] The mass spectrometer includes an ion supply unit 1, a linear ion trap 2, a mass analysis and detection unit 3, a control unit 4, and a power supply unit 5. Although not shown, the ion supply unit 1, the linear ion trap 2, and the mass analysis and detection unit 3 can be arranged inside a vacuum chamber or the like.

[0043] The ion supply unit 1 includes an ion source and the like, and the ion supply unit 1 ionizes various components contained in the sample and supplies ions to the linear ion trap 2 in a direction substantially along the ion optical axis C (Z-axis direction). The linear ion trap 2 includes a plurality of (inFigure 4 Although only four are depicted in Figure 4 , there are actually six rod electrodes 201 to 206. Ions are temporarily held in the internal space (ion trapping space) 200 surrounded by these rod electrodes 201 to 206, and the held ions are discharged in the direction along the ion optical axis C in descending order of m / z. That is, the linear ion trap 2 is an axially discharging type linear ion trap capable of mass scanning.

[0044] The power supply unit 5 applies voltages to the respective electrodes included in the linear ion trap 2 under the control of the control unit 4. The mass analysis and detection unit 3 is configured to include one or more mass separators and a detector, or is configured to include only a detector. In the former case, the mass analysis and detection unit 3 further separates the ions discharged from the linear ion trap 2 according to m / z and then performs detection. On the other hand, in the latter case, the mass analysis and detection unit 3 directly detects the ions discharged from the linear ion trap 2. The specific configuration of the mass analysis and detection unit 3 is shown in the configuration examples described later. The control unit 4 is generally configured to include a CPU, a ROM, a RAM, etc., and outputs control signals to each part such as the power supply unit 5 according to a preset control program to execute an analysis operation.

[0045] [Configuration of Linear Ion Trap]

[0046] Figure 3 is for explaining in detail Figure 4 the electrode structure of the linear ion trap 2 in Figure 4 . (A) is a schematic front longitudinal sectional view, (B) is a line-of-sight sectional view in the A-AA direction in (A), and (C) is a line-of-sight sectional view in the B-BB direction in (A). Figure 1 is a schematic perspective view showing the structure of the rod electrode, Figure 2 is an auxiliary view for explaining the structure of the rod electrode.

[0047] As Figure 3 shown, the linear ion trap 2 includes: a rod electrode group 20, which is composed of six rod electrodes 201, 202, 203, 204, 205, and 206 arranged so as to surround a linear ion optical axis C extending in the Z-axis direction; a three-dimensional ion trap partial electrode 21, which is continuously (electrically connected) provided at the end of the rod electrode group 20 on the ion emission side (the right side in this figure); an inlet side end cap electrode 22, which is arranged outside the end of the rod electrode group 20 on the ion incident side (the left side in this figure), has a substantially disc shape and has a circular opening 22a in the center; and a disc-shaped extraction electrode 23, which is arranged outside the three-dimensional ion trap partial electrode 21 and has a substantially circular opening 23a. The extraction electrode 23 also serves as the outlet side end cap electrode of a normal linear ion trap.

[0048] As Figure 3As shown in (B), the six rod electrodes 201 to 206 are circumscribed with a circle (shown by a dotted line in the figure) centered on the ion optical axis C and are arranged at equal angles (60°) around the ion optical axis C. On the other hand, the three-dimensional ion trap partial electrode 21 is composed of Figure 2 The two annular electrodes 212, 213 of the hexapole three-dimensional ion trap shown in the figure and a part of the two spherical electrodes 211, 214 sandwiching the two annular electrodes 212, 213 are electrodes obtained by exactly dividing these electrodes in two on the XY plane orthogonal to the ion beam axis C (Z axis). Here, the four electrodes constituting the three-dimensional ion trap partial electrode 21 are added with the same Figure 2 The annular electrode and the spherical electrode shown in the figure have the same reference numerals to clarify the corresponding relationship.

[0049] The diameters of the spherical electrodes 211 and 214 are equal to the diameters of the rod electrodes 201 and 204, and the diameters of the annular electrodes 212 and 213 are equal to the diameters of the rod electrodes 202, 203, 205, and 206. Therefore, the rod electrode 201 and the spherical electrode 211, the rod electrode 204 and the spherical electrode 214, the rod electrodes 202 and 206 and the annular electrode 212, and the rod electrodes 203 and 205 and the annular electrode 213 are connected without steps and become one body. That is, the rod electrodes 202 and 206 and the annular electrode 212, and the rod electrodes 203 and 205 and the annular electrode 213 are electrodes that are U-shaped in a plan view. In addition, the rod electrode 201 and the spherical electrode 211, and the rod electrode 204 and the spherical electrode 214 are linear electrodes with one end being spherical.

[0050] Among them, Figure 3 As shown in (C), the portion of the two annular electrodes 212 and 213 sandwiching the ion optical axis C that points to the ion optical axis C becomes a cylindrical defect 212a and 213a that is hollowed out with the ion optical axis C as the center axis. The defect 212a and 213a cooperate with the gap between the original two annular electrodes 212 and 213 (i.e., in a state without the defect), so that it can function as an ion extraction opening 210 that allows the DC electric field formed by the extraction electrode 23 to enter the ion capture space 200 and extract ions using the electric field as described later.

[0051] like Figure 4As shown, a prescribed DC voltage can be applied from the inlet-side electrode DC power supply unit 51 included in the power supply unit 5 to the inlet-side end cap electrode 22. A prescribed DC voltage is applied from the extraction electrode DC power supply unit 52 to the extraction electrode 23. A prescribed RF voltage is applied from the RF power supply unit 50 to each of the rod electrodes 201 to 206 included in the rod electrode group 20 and each of the electrodes 211 to 214 included in the three-dimensional ion trap partial electrodes 21, respectively. Specifically, the RF voltage applied to the six rod electrodes 201 to 206 is an RF voltage having the same amplitude and frequency and whose polarity is reversed (i.e., the phase is shifted by 180°) between two circumferentially adjacent rod electrodes. Here, since the two rod electrodes 202 and 206 are connected via the ring electrode 212 and the other two rod electrodes 203 and 205 are connected via the ring electrode 213, by applying the RF voltage to the four rod electrodes 201, 202, 203, and 204 shown in Figure 4 , it is possible to apply the required RF voltage to all the electrodes included in the rod electrode group 20 and the three-dimensional ion trap partial electrodes 21.

[0052] [Operation of Linear Ion Trap]

[0053] Next, an example of the basic operation of the linear ion trap 2 will be described. Figure 6 is an example of the change in the applied voltage when driving the linear ion trap 2 and is a timing chart in the case of performing mass scanning by changing the RF voltage. Figure 7 is another example of the change in the applied voltage when driving the linear ion trap 2 and is a timing chart in the case of performing mass scanning by changing the extraction DC voltage.

[0054] In Figure 4 , the ion supply unit 1 transports various ions derived from a sample to be analyzed in a direction substantially along the ion optical axis C. The inlet-side electrode DC power supply unit 51 applies a DC voltage that changes at a prescribed timing to the inlet-side end cap electrode 22, thereby forming a DC electric field that receives only the ions supplied from the ion supply unit 1 during a prescribed period and intercepts the ions near the inlet-side end cap electrode 22 if the period is exceeded. In addition, the RF power supply unit 50 forms a multipole RF electric field that captures various ions introduced into the ion capture space 200 through the opening 22a of the inlet-side end cap electrode 22 by applying a prescribed RF voltage to each of the rod electrodes 201 to 206. The extraction electrode DC power supply unit 52 applies a DC voltage that can form a DC electric field for pushing back the ions, so that the ions do not leak from the ion capture space 200.

[0055] The multipolar RF electric field generates an RF pseudopotential that confines ions. In a linear ion trap, characteristics such as the mass dependence of the ion confinement ability, or the converging force that concentrates ions near the central axis, change according to the number of rod electrodes, i.e., the number of poles. Generally, the larger the number of poles, the smaller the mass dependence of the confinement ability (able to confine ions with a wider m / z range), but the converging force is also smaller. Therefore, a six-pole configuration is used as the linear ion trap here, but a number of poles other than six can also be selected according to the desired characteristics. Specifically, theoretically, an N-pole configuration can be adopted as follows: N = 6 + 4M (where M is 0, 1, 2, …). In any case, various ions derived from a sample can be confined in the ion capture space 200 under the action of the RF pseudopotential generated by the multipolar RF electric field.

[0056] In addition, although not shown, an inert gas such as helium or argon can be introduced into the interior of the linear ion trap 2 through an inert gas introduction tube. The various ions captured by the ion capture space 200 come into contact with the inert gas and lose their kinetic energy. That is, the various ions are cooled in the ion capture space 200, whereby the diffusion of ions in the longitudinal direction (Z-axis direction) is suppressed, and they tend to exist near the ion optical axis C.

[0057] For example, when the target ions are positive ions, during ion accumulation and cooling, the polarity of the DC voltage applied to the extraction electrode 23 is Figure 6 as shown, the same polarity as the ions, i.e., the positive polarity. The confinement effect of the RF pseudopotential and the confinement effect of the electric field formed by the DC voltages applied to the inlet-side end cap electrode 22 and the extraction electrode 23 complement each other to well confine the ions in the ion capture space 200.

[0058] After cooling the ions for a specified time, as Figure 6 shown, the extraction DC voltage applied to the extraction electrode 23 is switched to the opposite polarity to the ion polarity (negative polarity in this case). The electric field formed by this negative-polarity DC voltage has the effect of attracting ions, and they reach the ion capture space 200 through the ion extraction opening 210 including the defective portions 212a, 213a. Therefore, when ions are captured in the ion capture space 200 using the multipolar RF electric field as described above, the force based on the DC electric field also acts on these ions. However, at this time, compared with the force acting on the ions by the DC electric field, the confinement effect of the RF pseudopotential is greater, so the ions can stay in the ion capture space 200.

[0059] As described above, while or immediately after switching the polarity of the extraction DC voltage, the RF power supply unit 50 changes the amplitude of the RF voltage applied to the rod electrodes 201 to 206 in a gradually decreasing manner. The strength of the ion confinement effect of the RF pseudopotential inside the linear ion trap is inversely proportional to the mass of the ions. That is, the larger the m / z value of the ion, the smaller the confinement effect of the RF pseudopotential, and the easier it is to escape from the ion capture space 200. Therefore, if the amplitude of the RF voltage applied to the rod electrodes 201 to 206 is changed in a gradually decreasing manner, the confinement force on the ions becomes weaker in the direction from ions with relatively large m / z to ions with successively smaller m / z. In contrast, the extraction DC electric field generated by the extraction electrode 23 acts uniformly on the ions regardless of the mass of the ions. Therefore, starting from the ions whose confinement force of the RF pseudopotential becomes weaker, that is, starting from the ions with larger m / z, they are attracted by the extraction DC electric field in turn and are extracted outward roughly along the Z-axis direction (along the ion optical axis C) through the ion extraction opening 210 and the opening 23a of the extraction electrode 23.

[0060] like Figure 6 As shown in FIG. 1 , if the extraction DC voltage is maintained at a constant value and the amplitude of the RF voltage is changed in a manner of gradually decreasing, the ions captured in the ion trapping space 200 of the linear ion trap 2 are sequentially ejected from the ions with higher m / z values ​​through the ion extraction opening 210 and the opening 23a. That is, mass scanning in the direction of decreasing m / z values ​​of the ions extracted from the linear ion trap 2 is achieved.

[0061] Instead of gradually decreasing the amplitude of the RF voltage as described above, Figure 7 By changing the voltage value of the DC voltage applied to the extraction electrode 23 as shown, the extraction DC electric field is gradually enhanced while the amplitude of the RF voltage is maintained at a constant value, that is, while the ion confinement effect of the RF pseudopotential is maintained at a constant value. Thus, it is possible to perform mass scanning in a direction in which the m / z value of the ions extracted from the ion trapping space 200 decreases, similarly to the case of changing the amplitude of the RF voltage as described above.

[0062] But, like Figure 7 As in the example of , if the extraction DC voltage is gradually changed for mass scanning, the energy of the ions after passing through the extraction electrode 23 will change accordingly. Therefore, when this energy change is not a problem, this control method can be used. On the other hand, when the linear ion trap is arranged in a collision cell in a Q-TOF type mass spectrometer as described later, it is desired to keep the kinetic energy of the ions discharged from the linear ion trap constant regardless of the m / z value. Therefore, in this case, Figure 6As shown, a control method of performing mass scanning by changing the amplitude of the RF voltage instead of changing the extraction DC voltage can be adopted.

[0063] Figure 5 This is an example of the result of simulating the trajectory of ions from the ion capture space 200 of the linear ion trap 2 where ions are introduced to the time when they are extracted outward. Here, in order to make the ion trajectory easy to understand, only the trajectory of one ion is depicted.

[0064] From Figure 5 It can be seen that ions enter through the opening 22a of the inlet-side end cap electrode 22 and collide with the gas present in the ion capture space 200, thereby being cooled and accumulated in the ion capture space 200. At this time, a DC voltage equal to that of the inlet-side end cap electrode 22 is applied to the extraction electrode 23 in advance. At the timing of extracting ions, the polarity of the DC voltage applied to the extraction electrode 23 is switched, the extraction DC voltage is increased to gradually increase the extraction electric field, or the RF voltage is gradually decreased, so that the ions pass through the opening 23a in the order of decreasing m / z and are extracted axially to the outside.

[0065] Figure 8 and Figure 9 are diagrams showing the results of simulated calculations of the extraction efficiency of ions from the linear ion trap 2. Figure 8 is a diagram showing the relationship between the amplitude value of the RF voltage and the ion extraction efficiency when the extraction DC voltage is set to a constant -20V. Here, the target ion is only one type of m / z 400. Figure 9 is a diagram showing the relationship between the m / z value of ions and the extraction efficiency when the amplitude of the RF voltage and the extraction DC voltage are kept constant.

[0066] In Figure 8 and Figure 9 when the ion extraction efficiency is 0%, it means that the ions stably exist and are confined in the ion capture space 200. On the other hand, when the ion extraction efficiency is 100%, it means that the ions cannot stably exist in the ion capture space 200 and all ions are extracted. From Figure 8 It can be seen that in the state where the extraction DC voltage is maintained at a constant -20V and the amplitude of the RF voltage is set to 120V, the ions of m / z 400 are not extracted. And it can be seen that as the amplitude of the RF voltage is gradually decreased from about 115V, the ions of m / z 400 are gradually extracted little by little. If the amplitude of the RF voltage is set to about 100V or less, almost all the ions of m / z 400 are extracted, that is, discharged.

[0067] In addition, as described above, the ion confinement ability of the RF pseudopotential is inversely proportional to the mass of the ions. From Figure 9It can be confirmed that, under constant voltage conditions, the higher the quality of the ions, the easier they are to be ejected, obtaining the same effect as the principle of operating as a mass-related high-pass filter. In Figure 9 Under the voltage conditions shown, a mass selectivity is shown such that ions with m / z below 300 can be substantially retained in the ion trap space 200 and almost all ions with m / z above 400 can be ejected. This mass selectivity can be improved by optimizing the gas pressure (which affects ion cooling), the amplitude of the RF voltage, the extraction DC voltage, etc.

[0068] In addition, in Figure 9 , the extraction efficiency of ions with m / z above 500 shows a decreasing tendency due to the influence of the loss of ions during accumulation in the ion trap space 200. It can be presumed that this is because the ion confinement ability of the RF pseudopotential becomes weaker as the m / z increases. To improve the ion confinement ability, increasing the number of poles of the multipole field is effective. Therefore, especially when it is necessary to increase the supply amount of high-m / z ions, increasing the number of poles of the linear ion trap, that is, the number of rod electrodes, is sufficient.

[0069] Thus, in the above-mentioned linear ion trap 2, the gas pressure, the number of poles of the multipole field, the amplitude of the RF voltage, the extraction DC voltage, etc. are parameters that affect the performance. Through the combination and change methods of the values of these parameters, ion operations can be flexibly carried out according to the purpose, which is also one of the characteristics of this linear ion trap.

[0070] [Example of the Structure of a Mass Analyzer 1]

[0071] Describe a specific example of the structure of the above-mentioned mass analyzer.

[0072] There are various types of mass separators for mass analyzers, but currently, the most widely used is the quadrupole mass filter. In tandem mass analyzers, in addition to triple quadrupole mass analyzers, quadrupole-time-of-flight mass analyzers, quadrupole-Fourier transform mass analyzers, etc. also use quadrupole mass filters.

[0073] The quadrupole mass filter is an easy-to-use mass separator, but since it is a mass separator that selectively allows only ions with a specific m / z (or a certain m / z range) to pass through, there is a technical problem that a large number of ions with other m / z that cannot pass through are wasted. That is, the utilization efficiency of ions in the quadrupole mass filter is not necessarily high.

[0074] To solve this technical problem, the above-mentioned linear ion trap can be used. Figure 10 It is a schematic diagram of the general structure of the mass analyzer of Example 1.

[0075] In this mass analysis device, the above-mentioned mass analysis and detection unit 3 includes a quadrupole mass filter 31 and an ion detector 32. A linear ion trap 2 configured as described above is arranged at the pre-stage of the quadrupole mass filter 31. In addition, the ion supply unit 1 includes an ion source 10 and a pole number conversion ion guide 11. Ions emitted from the pole number conversion ion guide 11 are introduced into the linear ion trap 2. Here, the ion optical axes C of the pole number conversion ion guide 11, the linear ion trap 2, and the quadrupole mass filter 31 are aligned, that is, they are on a straight line.

[0076] The pole number conversion ion guide 11 is, for example, a multipole ion guide described in Patent Document 4. It is an ion guide in which at least a part of the rod electrodes are arranged obliquely with respect to the linear ion optical axis C, so that the pole number at the ion inlet end and the pole number at the ion outlet end are different. Here, 10 rod electrodes are used. At the ion inlet end, a decapole configuration is set in which the 10 rod electrodes are arranged at substantially equal angular intervals so as to surround the ion optical axis C. At the ion outlet end, a hexapole configuration is set in which only 6 out of the 10 rod electrodes are arranged at substantially equal angular intervals so as to surround the ion optical axis C.

[0077] Similar to the above-mentioned linear ion trap 2, in a multipole ion guide, the greater the pole number, the stronger the ion confinement ability. Therefore, by setting a configuration with a larger pole number at the ion inlet end, ions diffusing from the pre-stage ( Figure 10 here it is the ion source 10) can be efficiently trapped and taken into the internal space of the pole number conversion ion guide 11. On the other hand, for a smaller pole number, the ion convergence effect is stronger. Therefore, by setting a configuration with a relatively smaller pole number at the ion outlet end, ions can be converged near the ion optical axis C and delivered to the post-stage ( Figure 10 here it is the linear ion trap 2) without waste. In addition, in the pole number conversion ion guide 11, an axial electric field that transports ions (i.e., accelerates) along the traveling direction can be generated by applying a DC voltage to each rod electrode.

[0078] In this configuration, the ion outlet end of the pole number conversion ion guide 11 is set to a hexapole configuration in order to make the pole number at the ion outlet end of the pole number conversion ion guide 11 the same as the pole number of the linear ion trap 2, with the aim of making the mass selectivity of the multipole RF electric field consistent. However, this is not necessary.

[0079] Refer to Figure 11The timing chart shown illustrates the typical operation of this quality analysis device. Ions derived from the sample components generated by the ion source 10 are introduced into the pole-changing ion guide 11. As described above, in the internal space of the pole-changing ion guide 11, an axial electric field and a multipole RF electric field are formed in the direction of ion travel. Therefore, the ions are converged by this electric field and travel toward the outlet. A DC voltage is applied to the entrance-side end cap electrode 22 of the linear ion trap 2, which generally forms a potential barrier for the ions. Therefore, the ions reaching the outlet region of the pole-changing ion guide 11 are intercepted in front of the entrance-side end cap electrode 22 and accumulated in the outlet region of the pole-changing ion guide 11.

[0080] As Figure 11 shown, when the voltage applied to the entrance-side end cap electrode 22 is temporarily reduced at a specified timing, only at this time does the potential barrier disappear. Therefore, the ions accumulated in the outlet region of the pole-changing ion guide 11 are introduced into the ion capture space 200 of the linear ion trap 2 via the opening 22a. That is, the transfer of ions from the pole-changing ion guide 11 to the linear ion trap 2 is carried out in batches. After the accumulated ions are transferred, if the voltage applied to the entrance-side end cap electrode 22 rises again, the ions begin to accumulate in the outlet region of the pole-changing ion guide 11. Thus, by accumulating ions in the outlet region of the pole-changing ion guide 11, even when the period during which ions can be introduced into the linear ion trap 2 is limited, it is possible to avoid the loss of ions continuously fed from the ion source 10 and introduce the ions into the linear ion trap 2 with high efficiency.

[0081] The ions introduced into the ion capture space 200 are cooled by contact with the gas and sufficiently captured as described above. Then, by gradually reducing the amplitude of the RF voltage applied to the rod electrode group 20, the ions are extracted along the ion optical axis C through the opening 23a of the extraction electrode 23 in the order of decreasing m / z. At this time, the scanning of the RF voltage applied to the rod electrode group 20 of the linear ion trap 2 is synchronously controlled with the scanning of the voltage (a voltage obtained by superimposing an RF voltage and a DC voltage) applied to the quadrupole mass filter 31, so that the ions having a specified m / z discharged from the linear ion trap 2 are screened by the subsequent quadrupole mass filter 31, that is, made to coincide with the m / z of the ions passing through the quadrupole mass filter 31.

[0082] In an existing quadrupole type mass analyzer that uses a quadrupole mass filter as a mass separator, when performing a mass scan using the quadrupole mass filter, ions other than those passing through the quadrupole mass filter are discarded, so the utilization efficiency of ions is not necessarily high. In contrast, in the mass analyzer of Configuration Example 1 described above, only ions with an m / z that can roughly pass through the quadrupole mass filter 31 among the ions accumulated in the linear ion trap 2 are selectively discharged from the linear ion trap 2 and sent to the quadrupole mass filter 31. Therefore, ions that would have been lost in the quadrupole mass filter in the past can be effectively utilized. As a result, compared with the existing quadrupole type mass analyzer, higher sensitivity can be achieved. In addition, most of the ions derived from the sample components generated in the ion source 10 can be used for mass analysis. Therefore, even when ions with a specific m / z are temporarily generated, it is not easy for these ions to be missed, which is useful for comprehensively grasping the ions derived from the sample components.

[0083] The above Configuration Example 1 is a single-type quadrupole type mass analyzer, but it can also be configured as follows: in a triple quadrupole type mass analyzer capable of performing MS / MS analysis, the above linear ion trap 2 is arranged in front of the first-stage quadrupole mass filter. In this case, when performing a mass scan by the first-stage quadrupole mass filter, such as precursor ion scan measurement or neutral loss scan measurement, it is only necessary to synchronously control the linear ion trap 2 and the first-stage quadrupole mass filter so that the m / z of the ions discharged from the linear ion trap 2 is approximately the same as the m / z of the ions passing through the first-stage quadrupole mass filter.

[0084] [Configuration Example 2 of Mass Analyzer]

[0085] In a Q-TOF type mass analyzer in which a collision cell is arranged between a quadrupole mass filter and an orthogonal acceleration time-of-flight type mass separator, various product ions can be generated from one type of precursor ion in the collision cell, but the time required for the ions discharged from the collision cell to reach the orthogonal acceleration section depends on the m / z of the ions and is different. Therefore, when accelerating the ions pulsedly through the orthogonal acceleration section, sometimes only the product ions within a limited m / z range among the various m / z product ions derived from one type of precursor ion can be accelerated. In this case, the m / z range of the product ions that can be observed is limited, and there is a technical problem that a correct product ion spectrum cannot be obtained.

[0086] To solve the above technical problem, the mass analyzer of Configuration Example 2 is a device that utilizes the above linear ion trap 2. Figure 12 It is a schematic configuration diagram of the mass analyzer of Configuration Example 2.

[0087] In this mass analysis device, the above-described mass analysis and detection unit 3 includes a quadrupole mass filter 33, an orthogonal acceleration time-of-flight mass separator 34, and an ion detector 32. Inside a collision cell (not shown) between the quadrupole mass filter 33 and the orthogonal acceleration time-of-flight mass separator 34, the linear ion trap 2 configured as described above is disposed. Additionally, in Figure 12 the description of the components corresponding to the above-described ion supply unit 1 is omitted. The orthogonal acceleration time-of-flight mass separator 34 includes: an orthogonal acceleration unit 341 including a pair of extraction electrodes 341A and introduction electrodes 341B, an acceleration electrode 342, a flight tube 343, and a reflection electrode 344.

[0088] The quadrupole mass filter 33 selectively allows ions having a specific m / z among the ions supplied from an ion supply unit (not shown) to pass through. The ions are introduced into the ion capture space 200 of the linear ion trap 2, come into contact with the collision gas supplied to the ion capture space 200, and dissociate to generate various product ions. The generated product ions are captured by the ion capture space 200 through the RF electric field. After that, the extraction DC voltage is maintained constant, and the RF voltage applied to the rod electrode group 20 is changed, whereby the product ions captured in the ion capture space 200 are discharged through the ion extraction opening 210 and the opening 23a in descending order of m / z. The discharged ions travel substantially along the ion optical axis C and reach the orthogonal acceleration unit 341.

[0089] In a state where the extraction DC voltage is maintained at a constant value, a constant energy is imparted to each ion discharged from the linear ion trap 2 regardless of m / z by the action of the extraction DC electric field generated by this voltage. Therefore, the ions with relatively smaller m / z that are discharged later move at a greater speed than the ions with relatively larger m / z that are discharged earlier in time. Thus, by appropriately controlling the change in the RF voltage, all the ions with different m / z values discharged from the linear ion trap 2 at different times can reach a specified position inside the orthogonal acceleration unit 341 almost simultaneously.

[0090] In the orthogonal acceleration time-of-flight mass separator 34, ions are introduced into the orthogonal acceleration unit 341 in the Z-axis direction along the ion optical axis C. At the timing when various ions with different m / z values are incident on the orthogonal acceleration unit 341 almost simultaneously as described above, a specified pulsed DC voltage is applied to the extraction electrodes 341A and the introduction electrodes 341B, respectively. Thereby, the ions with various m / z values passing through the orthogonal acceleration unit 341 at this time are pushed out in the Y-axis direction through the slit of the introduction electrode 341B, and then are accelerated by the acceleration electrode 342 and ejected into the flight tube 343.

[0091] Ions fly within the flight tube 343, and after being turned back by the electric field formed by the reflection electrode 344, they fly within the flight tube 343 again. Thus, the ions flying along the turning-back orbit C1 finally reach the ion detector 32 and are detected. Ions ejected from the orthogonal acceleration section 341 almost simultaneously fly with flight times corresponding to m / z respectively, and thus are separated according to m / z during flight, and reach the ion detector 32 in order starting from ions with smaller m / z.

[0092] Thus, in the mass analyzer of this structural example 2, ions with a wide range of m / z supplied from the linear ion trap 2 can be sent into the flight space without waste for mass analysis. Thereby, product ions with a wide range of m / z can be detected with high sensitivity.

[0093] In this mass analyzer, as described above, in order for all ions ejected from the linear ion trap 2 to reach a specified position in the orthogonal acceleration section 341 almost simultaneously, it is only necessary to control the extraction of ions from the linear ion trap 2 under the following conditions.

[0094] Now, as Figure 12 shown, let the distance from the extraction electrode 23 to the orthogonal acceleration section 341 be L, and let the length of the ion passage region of the orthogonal acceleration section 341 be D. In addition, let the space from the extraction electrode 23 to the orthogonal acceleration section 341 be at the same potential. Further, assume that the energy of the ions ejected from the linear ion trap 2 is the energy accelerated by the DC voltage V starting from the state where the ions are sufficiently cooled, and let it be eV E . If it is assumed that the ions do not collide with neutral particles during the period from the extraction electrode 23 to the orthogonal acceleration section 341, then in the prior art where all ions are extracted from the ion trap almost simultaneously, the time t for the ions with the lightest mass m1 to reach the outlet of the orthogonal acceleration section 341 is shown by the following formula (1). E .

[0095] t = (D + L)√(m1 / 2eV E )…(1)

[0096] The maximum mass m2 that can be observed simultaneously is the mass of the ions that can reach the inlet of the orthogonal acceleration section 341 at the same time, and its arrival time t becomes the following formula (2).

[0097] t = D√(m2 / 2eV E )…(2)

[0098] Therefore, the mass range of the ions that can be observed is shown by the following formula (3).

[0099] m2 / m1 = {(D + L) / D} 2 …(3)

[0100] In contrast, as described above, by using the linear ion trap 2 that expels ions in descending order of m / z, ions with a heavier mass can be sent out first. Therefore, it is possible to control so that these ions with a heavier mass and the ions with a lighter mass that are sent out later arrive at a certain position of the orthogonal acceleration unit 341 at the same time. Considering the case where ions of all masses arrive at the center of the orthogonal acceleration unit 341 at the same time, the arrival time of the ions with the maximum mass m2 is

[0101] t = {D+(L / 2)}√(m2 / 2eV E )…(4)

[0102] The delay time t in the RF voltage control required for these ions to arrive at the same time as the ions with the minimum mass m1 is D as follows.

[0103] t D = {D+(L / 2)}{(√m2 - √m1) / √(2eV E )}…(5)

[0104] That is, in order to extract ions from the linear ion trap 2, by scanning the RF voltage in such a way as to have the above delay time t D all ions in the target mass range can arrive at the same position in the orthogonal acceleration unit 341 almost simultaneously. Thus, compared with the prior art, not only is the mass range of the ions to be observed expanded, but also the deviation of the initial position of the ions in the orthogonal acceleration unit 341 is reduced. Therefore, an improvement in detection sensitivity and mass resolution is also achieved. In addition, in this Configuration Example 2, as described above, in order to keep the energy of the ions extracted from the linear ion trap 2 constant, it is only necessary to extract ions in descending order of m / z by scanning the RF voltage instead of extracting a DC voltage.

[0105] [Configuration Example 3 of Mass Analyzer]

[0106] Figure 13 is a configuration diagram of the main part of the mass analyzer of Configuration Example 3. The mass analyzer of this Configuration Example 3 is a device formed by combining the above linear ion trap 2 with the pre-stage of the multiple-rounding Fourier transform type mass separator 36. In this configuration, the ions discharged from the linear ion trap 2 are introduced into the multiple-rounding Fourier transform type mass separator 36 through the ion incident unit 35 and fly along the rounding orbit C2. The voltage applied to the electrodes constituting the ion incident unit 35 can be switched in the following manner: during the ion incidence period, an incident electric field is formed to make the ions coming from the above linear ion trap 2 ride on the rounding orbit C2, and during the ion rounding period, a rounding electric field is formed to make the ions fly along the rounding orbit C2.

[0107] In the existing mass spectrometry apparatus of this type, ions ejected from the ion trap substantially simultaneously need to be loaded onto the orbit C2 substantially simultaneously. Therefore, the m / z range of ions to be mass-analyzed simultaneously needs to be limited to a narrow range. In contrast, in the mass spectrometry apparatus of Configuration Example 3, as in Configuration Example 2, ions with a large m / z and a relatively slow flight speed are first ejected from the linear ion trap 2, and the ions are gradually ejected in descending order of m / z and loaded onto the orbit C2. Thus, ions with all m / z values can reach any position on the orbit C2 substantially simultaneously. As a result, the m / z range of ions to be observed can be expanded. In addition, during the period from when the first ion that has made one revolution among the ions introduced into the orbit C2 via the ion incident section 35 returns to the ion incident section 35, it is necessary to switch the voltage applied to the ion incident section 35. However, ions with a small m / z are introduced into the orbit C2 with a delay compared to ions with a large m / z. Therefore, the period during which ions are loaded onto the orbit C2 by the ion incident section 35 can be extended, and more ions can be subjected to mass spectrometry. As a result, an improvement in detection sensitivity can also be achieved.

[0108] In addition, in this case, the delay time t is calculated using Equation (5). D When doing so, L may be set to the flight length of the ion incident section 35, and D may be set to the flight length to the location where ions reach simultaneously on the orbit C2.

[0109] [Modification Example of Linear Ion Trap]

[0110] In the linear ion trap 2 described based on Figure 1 , Figure 3 etc., the three-dimensional ion trap partial electrode 21 is used to enhance the confinement effect of the multipole RF electric field on ions at the end of the rod electrode group 20 on the side of the extraction electrode 23, and is equivalent to the auxiliary electrode in the present invention. In the absence of this auxiliary electrode (i.e., in the absence of the RF electric field generated by the auxiliary electrode), when an extraction DC voltage is applied to the extraction electrode 23, ions with a relatively small m / z that are not sufficiently captured by the RF electric field may leak out simultaneously with ions with a relatively large m / z. Therefore, it is necessary to arrange an auxiliary electrode that forms an RF electric field for preventing ion leakage between the end of the rod electrode group 20 and the extraction electrode 23. However, the configuration or shape of this auxiliary electrode is not limited to the above description.

[0111] Specifically, in the above linear ion trap 2, the electrodes of the rod electrode group 20 and the three-dimensional ion trap partial electrode 21 are integrated, but they may also be separate. That is, as Figure 14As shown, a three-dimensional ion trap partial electrode 21A having the same constitution and shape as the above-described three-dimensional ion trap partial electrode 21 can also be arranged to have a predetermined gap (a gap of length d in this example) from the end of the rod electrode group 20. Of course, at this time, RF voltages similar to those in the above example are also applied to the respective electrodes constituting the three-dimensional ion trap partial electrode 21. In addition, in this case, different voltages can be applied to the respective electrodes of the rod electrode group 20 and the respective electrodes of the three-dimensional ion trap partial electrode 21. Therefore, by keeping the RF voltage applied to the respective electrodes of the rod electrode group 20 constant and only scanning (changing) the RF voltage applied to the respective electrodes of the three-dimensional ion trap partial electrode 21, ion ejection corresponding to m / z can also be performed.

[0112] In addition, it is also possible to use Figure 15 an RF grid electrode 21B formed by combining two semi-circular ring electrodes as viewed from above in place of the three-dimensional ion trap partial electrodes 21 and 21A as an auxiliary electrode. This RF grid electrode 21B is arranged inside a circular ring electrode to which an appropriate DC voltage is applied, and RF voltages with phases reversed from each other are applied to the two electrodes constituting the RF grid electrode 21B. By applying such RF voltages, an axial bipolar RF electric field is formed in the space inside the RF grid electrode 21B. This bipolar RF electric field functions as an RF pseudo-barrier with respect to ions captured in the ion capture space 200, and prevents ions from leaking toward the extraction electrode 23 when the amplitude of the applied RF voltage is large.

[0113] Figure 16 is an example of a timing chart of changes in applied voltages when driving Figure 15 the linear ion trap shown. In this constitution, when ions are extracted from the ion capture space 200 in descending order of m / z, both the extraction DC voltage applied to the extraction electrode 23 and the amplitude of the RF voltage applied to each of the rod electrodes 201 to 206 are maintained constant. Then, only the amplitude of the RF voltage applied to the RF grid electrode 21B is gradually decreased. The RF pseudo-barrier formed by the RF grid electrode 21B has different heights depending on the mass of the ions, and the larger the mass of the ions, the easier it is for them to cross the RF pseudo-barrier. Therefore, if the amplitude of the RF voltage applied to the RF grid electrode 21B is gradually decreased, similar to the linear ion trap in the above example, ions with larger m / z are sequentially ejected through the opening 23a, achieving axial ejection corresponding to m / z.

[0114] Figure 17 is an example of the result of simulating the trajectory of Figure 15 ions in the linear ion trap shown from when the ions are introduced into the ion capture space until they are extracted to the outside. In this case, similar to Figure 5Unlike the example shown, a hexapole electric field is not formed axially, but an RF pseudo-barrier is formed near the RF grid electrode 21B. Therefore, ions are trapped near the RF grid electrode 21B. For example, as the RF voltage is decreased, the ions are axially extracted to the outside in the order of decreasing m / z.

[0115] In addition, the above-described embodiments and configuration examples are merely examples of the present invention. Of course, within the scope of the gist of the present invention, even if modifications, additions, and corrections are appropriately made, they are included in the scope of the present claims.

[0116] Various solutions

[0117] Those skilled in the art can understand that the above-described exemplary embodiments are specific examples of the following solutions.

[0118] (Item 1) One solution of the mass analyzer of the present invention includes:

[0119] A linear ion trap section including a plurality of rod electrodes, an auxiliary electrode, and an extraction electrode, wherein the plurality of rod electrodes are arranged so as to surround a central axis, the auxiliary electrode is provided outside or protrudes from an outer end of one ion emission side of the plurality of rod electrodes and surrounds or sandwiches the central axis, and the extraction electrode is arranged further outside the auxiliary electrode;

[0120] An RF voltage generation section that applies an RF voltage to the plurality of rod electrodes and the auxiliary electrode in order to form an RF electric field in an ion trapping space surrounded by the plurality of rod electrodes and the auxiliary electrode;

[0121] An extraction voltage generation section that applies a DC voltage to the extraction electrode so that a DC electric field for extracting ions reaches the ion trapping space; and

[0122] A control section that is a control section for controlling the RF voltage generation section and the extraction voltage generation section, and changes at least one of the RF voltage or the DC voltage in a state where ions are confined in the ion trapping space, thereby discharging the ions from the ion trapping space in a direction along the central axis according to the mass-to-charge ratio.

[0123] In the mass analysis device described in Item 1, the voltage scanned when extracting ions in the order of m / z from the linear ion trap can be either the RF voltage applied to the rod electrodes or the DC voltage applied to the extraction electrodes. Therefore, unlike the existing resonance excitation ejection, it is not necessary to superimpose and apply two different AC voltages, namely the RF voltage and the AC voltage, to the rod electrodes. Thus, according to the mass analysis device described in Item 1, it is possible to achieve mass scanning for releasing ions from the linear ion trap in the order of m / z, and simplify the configuration of the power supply device for driving the linear ion trap. As a result, the power supply device can be made smaller and lighter, and its cost can also be suppressed. In addition, since ions are ejected in the axial direction of the linear ion trap, when ion optical elements such as a quadrupole mass filter and a multipole ion guide are arranged in the subsequent stage, the ion optical axes of the two can be made coaxial, and the arrangement of the ion optical elements becomes easier.

[0124] (Item 2) In the mass analysis device described in Item 1, it can be set that the auxiliary electrode is a multipole three-dimensional ion trap partial electrode formed by cutting out a part of the electrode constituting the multipole three-dimensional ion trap, and the multipole three-dimensional ion trap has the same number of poles as the ion trap constituted by the plurality of rod electrodes.

[0125] That is, when the linear ion trap has a hexapole structure, a hexapole three-dimensional ion trap partial electrode can be used as the auxiliary electrode. By using such a multipole three-dimensional ion trap partial electrode, the action of the RF electric field formed at the ion ejection side end of the rod electrodes can be enhanced, leakage of ions other than the target m / z when ejecting ions according to m / z can be reduced, and good mass scanning can be achieved.

[0126] (Item 3) In the mass analysis device described in Item 2, it can be set that the auxiliary electrode is formed with a defect portion in the multipole three-dimensional ion trap partial electrode, and the defect portion is formed by digging around the central axis of the multipole three-dimensional ion trap partial electrode.

[0127] For example, when using a hexapole three-dimensional ion trap partial electrode as the auxiliary electrode, in principle, ions can be extracted through the gap between the two ring electrodes sandwiching the central axis, but the size of the gap is not sufficient to allow a DC electric field of sufficient intensity to penetrate into the ion capture space. In contrast, according to the mass analysis device described in Item 3, since an opening of sufficient size can be provided between the two ring electrodes, a DC electric field of sufficient intensity can penetrate into the ion capture space through this opening, and ions can be well extracted from the ion capture space to the outside. Thereby, the ion extraction efficiency can be improved.

[0128] (Item 4) In the mass spectrometry apparatus according to any one of Items 1 to 3, it is possible to set the control unit to change the RF electric field while keeping the DC electric field constant, so that the ions captured by the ion capture space are sequentially discharged in the direction of decreasing mass-to-charge ratio.

[0129] In order to extract ions in the order of mass-to-charge ratio, either the DC electric field or the RF electric field can be changed. However, since the energy imparted to the ions when they are extracted is brought about by the DC electric field, if the DC electric field is changed, the energy possessed by the ions varies according to the mass-to-charge ratio. For example, in a case where it is desired to make ions discharged from a linear ion trap at different time points reach a certain position simultaneously as described later, this is disadvantageous. In contrast, according to the mass spectrometry apparatus described in Item 4, the energy possessed by the extracted ions is constant. Therefore, the moving speed of the ions depends on the mass-to-charge ratio, which is convenient for adjusting the arrival position of the ions.

[0130] (Item 5) In the mass spectrometry apparatus according to any one of Items 1 to 4, it is possible to set

[0131] A mass filter is disposed downstream of the linear ion trap unit.

[0132] The control unit synchronously controls the RF voltage and / or the DC voltage and the voltage applied to the mass filter, so that the mass-to-charge ratio of the ions discharged from the ion capture space is the same as the mass-to-charge ratio of the ions passing through the mass filter.

[0133] In the mass spectrometry apparatus described in Item 5, ions with an m / z value that can pass through the mass filter are discharged from the upstream linear ion trap and introduced into the mass filter. In other words, ions with an m / z value that cannot pass through the mass filter are retained in the linear ion trap until the time point when the ions can pass through the mass filter. Therefore, according to the mass spectrometry apparatus described in Item 5, by reducing the ions excluded by the mass filter, the generated ions can be effectively utilized to improve the detection sensitivity.

[0134] (Item 6) In the mass spectrometry apparatus according to any one of Items 1 to 4, it is possible to set

[0135] The linear ion trap unit includes an inlet-side end cap electrode outside the ion incident-side end of the plurality of rod electrodes on the side opposite to the ion emission side end.

[0136] The mass spectrometry apparatus further includes: an inlet-side voltage generation unit that switchably applies a voltage that allows ions to pass through and a voltage that blocks ions from passing through to the inlet-side end cap electrode.

[0137] A pole number conversion type ion guide is arranged at the pre-stage of the linear ion trap part, and the number of poles of the multipole field is different at the ion inlet end and the outlet end.

[0138] During the period when the inlet side voltage generating part applies a voltage to prevent ions from passing through to the inlet side end cap electrode, ions are accumulated in the outlet region of the pole number conversion type ion guide.

[0139] In the mass analyzer according to Item 6, although the period for introducing ions from the pole number conversion type ion guide into the linear ion trap is limited, during the period other than this introduction period, the ions transported by the pole number conversion type ion guide are accumulated in the outlet region of the ion guide and are introduced into the linear ion trap during the next introduction period. Therefore, even when ions are continuously transported by the pole number conversion type ion guide, the ions are not discarded but are reliably introduced into the linear ion trap. Thereby, the amount of ions available for mass analysis can be increased, and the detection sensitivity can be improved. In addition, for ions generated only temporarily, it is not easy to miss the detection, and accurate analysis can be performed.

[0140] (Item 7) In the mass analyzer according to any one of Items 1 to 4, it can be set that the control unit adjusts the speed or the time required for the change when the RF voltage and / or the DC voltage changes, so that all the ions discharged from the linear ion trap part or ions in a specified mass-to-charge ratio range among the discharged ions reach a specified position at a specified distance from the linear ion trap part simultaneously.

[0141] If ions are discharged from the linear ion trap in the order of decreasing m / z, then if the energy given to the ions is the same, the larger the m / z, the smaller the speed of the ion. Therefore, the ions with relatively smaller m / z that are discharged later are delayed in catching up with the ions with relatively larger m / z that are discharged earlier. Therefore, for example, if the speed of the change of the RF voltage or the time required for the change is adjusted such that the DC voltage used for extracting ions is kept constant and the RF electric field changes appropriately, all the ions can reach a certain position almost simultaneously. This is convenient when various ions with different m / z are desired to start from approximately the same position. Specifically, in the case where ions are desired to be ejected from the orthogonal acceleration part by an orthogonal acceleration time-of-flight mass separator, or in the case where ions are desired to start simultaneously from a certain position on the circumferential orbit by a Fourier transform type mass separator, etc.

[0142] (Item 8) In the mass analyzer according to Item 7, it can be set that an orthogonal acceleration time-of-flight mass separator is arranged at the lower stage of the linear ion trap part, and the specified position is a specified position in the orthogonal acceleration part of the orthogonal acceleration time-of-flight mass separator.

[0143] According to the mass analysis device described in Item 8, ions with a wide range of m / z can be ejected from the orthogonal acceleration section approximately simultaneously, so that the m / z range of the ions to be observed can be expanded. In addition, by subjecting more ions to mass analysis, the detection sensitivity can be improved.

[0144] (Item 9) In the mass analysis device described in Item 7, it can be configured such that a Fourier transform type mass separator is disposed at a lower stage of the linear ion trap section, and the specified position is a specified position on the ion orbit in the Fourier transform type mass separator.

[0145] According to the mass analysis device described in Item 9, ions with a wide range of m / z can be introduced into the Fourier transform type mass separator, so that the m / z range of the ions to be observed can be expanded. In addition, by subjecting more ions to mass analysis, the detection sensitivity can be improved.

[0146] Explanation of reference numerals

[0147] 1 Ion supply section

[0148] 10 Ion source

[0149] 11 Pole number conversion ion guide

[0150] 2 Linear ion trap

[0151] 20 Rod electrode group

[0152] 200 Ion capture space

[0153] 201, 202, 203, 204, 205, 206 Rod electrodes

[0154] 21, 21A Three-dimensional ion trap partial electrodes

[0155] 210 Ion extraction opening

[0156] 211, 214 Spherical electrodes

[0157] 212, 213 Ring electrodes

[0158] 212a, 213a Defective parts

[0159] 21B RF grid electrode

[0160] 22 Inlet side end cap electrode

[0161] 22a, 23a Openings

[0162] 23 Extraction electrode

[0163] 3 Mass analysis and detection section

[0164] 31, 33 Quadrupole mass filter

[0165] 32 Ion detector

[0166] 34 Orthogonal acceleration time-of-flight mass separator

[0167] 341 Orthogonal acceleration section

[0168] 342 Acceleration electrode

[0169] 343 Flight tube

[0170] 344 Reflector electrode

[0171] 35 Ion incident section

[0172] 36 Multiple-ring Fourier transform mass separation section

[0173] 4 Control section

[0174] 5 Power supply section

[0175] 50 RF power supply section

[0176] 51 Inlet-side electrode DC power supply section

[0177] 52 Extraction electrode DC power supply section

[0178] C Ion optical axis

[0179] C1 Return path

[0180] C2 Orbit.

Claims

1. A mass analysis device, characterized in that: have: A linear ion trap section, comprising a plurality of rod electrodes, an auxiliary electrode and an extraction electrode, wherein the plurality of rod electrodes are arranged in a manner of surrounding a central axis, the auxiliary electrode is arranged outside an ion ejection side end of one of the plurality of rod electrodes or is protruded from the ion ejection side end and surrounds or clamps the central axis, and the extraction electrode is arranged further outside the auxiliary electrode; an RF voltage generating unit for applying an RF voltage to the plurality of rod electrodes and the auxiliary electrode in order to form an RF electric field in the ion trapping space surrounded by the plurality of rod electrodes and the auxiliary electrode; An extraction voltage generating unit applies a DC voltage to the extraction electrode so that a DC electric field for extracting ions reaches the ion capturing space; as well as A control unit is a control unit for controlling the RF voltage generating unit and the extraction voltage generating unit. When ions are confined in the ion capturing space, the control unit changes at least one of the RF voltage or the DC voltage, thereby expelling the ions from the ion capturing space in a direction along the central axis according to the mass-to-charge ratio.

2. The mass spectrometer according to claim 1, wherein: The auxiliary electrode is a partial electrode of a multipole three-dimensional ion trap formed by cutting out a part of an electrode constituting a multipole three-dimensional ion trap. The multipole three-dimensional ion trap has the same number of poles as a linear ion trap constituted by the plurality of rod electrodes.

3. The mass spectrometer according to claim 2, wherein: The auxiliary electrode is formed by forming a notch in the multipole three-dimensional ion trap partial electrode, and the notch is formed by hollowing out the periphery of the central axis of the multipole three-dimensional ion trap partial electrode.

4. The mass spectrometer according to claim 1, wherein: The control unit makes the DC electric field constant and changes the RF electric field, thereby causing the ions trapped in the ion trapping space to be sequentially discharged in a direction in which the mass-to-charge ratio decreases.

5. The mass spectrometer according to claim 1, wherein: A mass filter is arranged at the lower stage of the linear ion trap section. The control unit synchronously controls the RF voltage and / or the DC voltage and the voltage applied to the mass filter so that the mass-to-charge ratio of ions discharged from the ion trapping space matches the mass-to-charge ratio of ions passing through the mass filter.

6. The mass spectrometer according to claim 1, wherein: The linear ion trap unit includes an entrance-side end cap electrode outside the ion incident-side end of the plurality of rod electrodes on the side opposite to the ion ejection-side end. The mass spectrometer further comprises: an entrance side voltage generating unit for applying a voltage for allowing ions to pass through and a voltage for preventing ions from passing through to the entrance side end cap electrode in a switchable manner; The pole number conversion type ion guide is arranged at the front stage of the linear ion trap part, and the pole number of the multipole field is different at the entrance end and the exit end of the ion. While the entrance-side voltage generator applies a voltage that blocks the passage of ions to the entrance-side end cap electrode, ions are accumulated in the exit region of the pole number conversion type ion guide.

7. The mass spectrometer according to claim 1, wherein: The control unit adjusts the speed of changing the RF voltage and / or the DC voltage or the time required for the change so that all ions discharged from the linear ion trap unit or ions in a specified mass-to-charge ratio range among the discharged ions simultaneously arrive at a specified position at a specified distance from the linear ion trap unit.

8. The mass spectrometer according to claim 7, wherein: An orthogonal acceleration time-of-flight mass separator is arranged below the linear ion trap. The predetermined position is a predetermined position in the orthogonal acceleration section of the orthogonal acceleration time-of-flight mass separator.

9. The mass spectrometer according to claim 7, wherein: A Fourier transform type mass separator is arranged at the lower stage of the linear ion trap section. The predetermined position is a predetermined position on the ion orbit in the Fourier transform mass separator.

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