Mass spectrometer and method for assembling the pre-rod and main rod of the mass spectrometer.

Abstract

Provided is a mass spectroscope capable of suppressing decreases in spectral sensitivity and resolution due to deformation during assembly of a multipole electrode. A mass spectroscope 28 comprises a multipole rod electrode 1 having a plurality of rod pairs (2A-1, 2A-2 ...). The rod pairs (2A-1, 2A-2 ...) are composed of pre-rods 2A-1 to 2D-1 and main rods 2A-2 to 2D-2 that are connected in the direction of an ion optical axis via an insulation member 6. In the multipole rod electrode 1, the pre-rods 2A-1 to 2D-1 constitute pre-rod electrode portions, and the main rods 2A-2 to 2D-2 constitute main rod electrode portions. The diameter of an inscribed circle 3 on which the pre-rod electrode portions 2A-1 to 2D-1 surround the ion optical axis is equal to the diameter of the inscribed circle 3 on which the main rod electrode portions surround the ion optical axis, and the diameter of all of the pre-rods 2A-1 to 2D-1 of the multipole rod electrode 1 is greater than the diameter of the main rods 2A-2 to 2D-2 connected to the pre-rods 2A-1 to 2D-1.

Description

Technical Field

[0001] The present invention relates to a method for assembling a pre-rod and a main rod of a mass spectrometer.

Background Art

[0002] In a mass spectrometer, MS / MS analysis is often performed, in which specific mass ions are selected from the ions generated by an ion source, the ions are decomposed, and the mass of the decomposed ions is analyzed to identify the detailed structure of the sample.

[0003] For example, in the case of a mass spectrometer in which all of an ion transport section (Q0), a first ion separation section (Q1), an ion dissociation section (Q2), and a second ion separation section (Q3) are composed of multipole rod electrodes (typically quadrupole rod electrodes), the ions generated by the ion source efficiently pass through Q0 by applying a high-frequency (RF) voltage to the multipole rod electrodes of Q0 and are introduced into Q1.

[0004] Q1 can transmit only ions having a specific mass from the introduced ions by applying an RF voltage and a direct current (DC) voltage to the multipole rod electrodes, and is thus called a quadrupole mass filter (QMF). The specific ions selected and separated by Q1 are introduced into Q2.

[0005] Q2 has a function of decomposing (CID) ions by colliding the ions with a neutral gas (such as nitrogen, helium, argon, etc.) in the Q2 atmosphere while transmitting the ions by applying an RF voltage to the multipole rod electrodes, and is thus called a collision cell. The ions decomposed by Q2 are introduced into Q3.

[0006] Q3 can transmit the introduced ions while separating them according to mass by applying an RF voltage and a DC voltage to the multipole rod electrodes in the same manner as Q1, and thus Q3 is also called a QMF. The ions separated by Q3 are discharged from the outlet according to mass and detected by a detector.

[0007] As such multi-pole rod electrodes, the technologies described in Patent Documents 1 and 2 are known.

[0008] Patent Document 1 states that "the four main rod electrodes (31a to 31d) included in the main electrode section (31) are arranged rotationally symmetrically around the ion optical axis (C), while of the four pre-rod electrodes (32a to 32d) included in the pre-electrode section positioned in front of the main electrode section (31), two are arranged so as to be tangent to a circle with radius r0, and the other two are arranged so as to be tangent to a circle with radius R0 which is larger than r0, thus being rotationally asymmetrical around the ion optical axis (C)."

[0009] As a result, the shape of the acceptance on the xy plane with respect to the ion position at the pre-electrode (32) becomes elliptical. As the ion propagates along the ion optical axis (C), the shape of the acceptance can be gradually flattened, reducing the mismatch between the emittance of the incident ion and the acceptance of the receiving side, thereby reducing ion loss during ion introduction.

[0010] As a result, it is stated that the overall ion transmittance of the quadrupole mass filter can be improved.

[0011] Furthermore, Patent Document 2 discloses a method and apparatus for reducing ion reflection between multipole segments in a mass spectrometer by matching the effective potentials between two segments.

[0012] The mass spectrometer has at least two multipole segments separated from each other along the longitudinal axis of the mass spectrometer such that there is a boundary region where ions are drawn from the upstream segment to the downstream segment, and each multipole segment further includes a set of spaced rod-shaped electrodes arranged around the longitudinal axis and having a field radius defined by the inscribed circle between the innermost parts of each electrode.

[0013] Effective potential matching can be achieved by either supplying RF signals of different amplitudes to each segment and / or modifying the field strength of the segments. In one embodiment, the multipole segments are described as being configured such that the upstream multipole segments have smaller field radii than the downstream segments. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] International Publication No. 2017 / 094146 [Patent Document 2] Special Publication No. 2022-513801 [Overview of the project] [Problems that the invention aims to solve]

[0015] In mass spectrometers, when assembling electrodes that constitute a multi-pole system such as a quadrupole, it is necessary to arrange the main rod and pre-rod in a straight line.

[0016] In this case, it is desirable to connect the main rod and the pre-rod, but if screws are used in the fixing part of the connection, deformation may occur due to the torque of the screws.

[0017] In other words, when the connecting parts are fixed using screws, the pre-rod, which has a short axial length, may shift in position due to the torque generated when turning the screws, potentially making it impossible to maintain linearity with the main rod.

[0018] If the linearity between the main rod and the pre-rod is compromised, it may lead to a decrease in the sensitivity and resolution of the detected spectrum.

[0019] The object of the present invention is to provide a mass spectrometer and a method for assembling the pre-rod and main rod of a mass spectrometer that can reduce the decrease in spectral sensitivity and resolution due to deformation during the assembly of multi-pole electrodes. [Means for solving the problem]

[0020] To achieve the above objective, the present invention is configured as follows.

[0021] A mass spectrometer is provided with a multipole rod electrode having a plurality of rod sets, wherein each rod set consists of a pre-rod and a main rod connected in the direction of the ion optical axis via an insulating member, and in the multipole rod electrode, the pre-rod constitutes a pre-rod electrode portion and the main rod constitutes a main rod electrode portion, wherein the diameter of the inscribed circle formed by the pre-rod electrode portion surrounding the ion optical axis is equal to the diameter of the inscribed circle formed by the main rod electrode portion surrounding the ion optical axis, and the diameters of all the pre-rods constituting the multipole rod electrode are greater than the diameter of the main rod connected to the pre-rod via the insulating member.

[0022] Furthermore, in the method for assembling the pre-rod and the main rod of a mass spectrometer, the end face of the pre-rod and the end face of the main rod are placed facing each other via an insulating member, the pre-rod, the insulating member and the main rod are temporarily fixed together with insulating screws, the pre-rod, the insulating member and the main rod are inserted into a cylindrical assembly guide jig, the lower side surface of the pre-rod and the lower side surface of the main rod are aligned with a reference line, a pre-rod position adjustment member is attached to the pre-rod via a pre-rod side position adjustment hole formed in the assembly guide jig, a main rod position adjustment member is attached to the main rod via a main rod side position adjustment hole formed in the assembly guide jig, the positions of the pre-rod and the main rod are aligned, the pre-rod and the main rod are fixed together, the pre-rod position adjustment member and the assembly position adjustment jig are removed, and the assembly guide jig is removed from the pre-rod and the main rod. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a mass spectrometer capable of reducing a decrease in sensitivity and a decrease in resolution of a spectrum due to deformation during assembly of a multi-pole electrode, and a method for assembling a pre-rod and a main rod of the mass spectrometer.

[0024] Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of Drawings

[0025] [Figure 1] Perspective view of a multi-pole rod electrode according to an embodiment. [Figure 2] Front view of a multi-pole rod electrode according to an embodiment. [Figure 3] Diagram showing a method for manufacturing a rod electrode according to an embodiment. [Figure 4] Diagram showing spectrum degradation due to deformation during rod connection. [Figure 5] More detailed explanatory diagram of a method for manufacturing a rod electrode according to an embodiment. [Figure 6] Diagram showing a spectrum after application of an embodiment. [Figure 7] Diagram showing the configuration of a mass spectrometer 28 when the ion transmission section 37 functions as an ion transport section Q0.

Modes for Carrying Out the Invention

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment

[0027] <Ion Transmission Section> A configuration will be described as an example in which a multi-pole rod electrode 1 constituting an ion transmission section 37 (shown in FIG. 7) is a quadrupole rod electrode including four rod sets of a pre-rod and a main rod.

[0028] FIGS. 1 and 2 show explanatory diagrams of the configuration of a quadrupole rod electrode using an embodiment of the present invention. FIG. 1 is a perspective view of the multi-pole rod electrode 1, and FIG. 2 is a front view of the multi-pole rod electrode 1.

[0029] In Figures 1 and 2, the multipolar rod electrode 1 is composed of four rod electrodes 2A to 2D. The four rod electrodes 2A to 2D are each divided into segment rods 2A-1, 2A-2, 2B-1, 2B-2, 2C-1, 2C-2, 2D-1, and 2D-2.

[0030] Of these, the segment rods 2A-1, 2B-1, 2C-1, and 2D-1, which are located upstream in the direction of the ion optical axis, are called pre-rods, while the segment rods 2A-2, 2B-2, 2C-2, and 2D-2, which are located downstream in the direction of the ion optical axis, are also called main rods.

[0031] Pre-rod 2A-1 and main rod 2A-2 are connected to each other in the direction of the ion optical axis. Similarly, pre-rod 2B-1 and main rod 2B-2, pre-rod 2C-1 and main rod 2C-2, and pre-rod 2D-1 and main rod 2D-2 are also connected to each other in the direction of the ion optical axis.

[0032] When the multipolar rod electrode 1 is used as the ion permeable section 37, ions are introduced from one end of the multipolar rod electrode 1 (the pre-rod 2A-1 to 2D-1 side), pass through the multipolar rod electrode 1, and are discharged from the opposite end (the main rod 2A-2 to 2D-2 side).

[0033] Next, the method for applying voltage to the multipole rod electrode 1 using a power supply and circuit will be described below.

[0034] High-frequency voltages with opposite phases are applied to rod electrodes 2A and 2B and rod electrodes 2C and 2D. Furthermore, different DC voltages V1 and V2 are applied to the pre-rod electrode section consisting of pre-rods 2A-1 to 2D-1 and the main rod electrode section consisting of main rods 2A-2 to 2D-2, respectively.

[0035] Each pre-rod 2A-1 to 2D-1 and main rod 2A-2 to 2D-2 are arranged around the ion optical axis, spaced apart with a field radius defined by the inscribed circle 3 between the innermost parts of each rod.

[0036] The ion-transmitting section 37 includes a power supply circuit (not shown) that supplies power to the multipole rod electrode 1 such that the effective potential of the pre-rod electrode section is greater than or substantially equal to the effective potential of the main rod electrode section, thereby reducing the reflection of ions transmitted through the boundary region.

[0037] In most cases, the length of the pre-rods 2A-1 to 2D-1 (length in the direction of the ion optical axis) is set to 10-20% of the length of the main rods 2A-2 to 2D-2 (length in the direction of the ion optical axis), so longer electrodes are used for the main rods 2A-2 to 2D-2.

[0038] As shown in Figure 3, the main rod 2A-2 has screw holes 10 on the side opposite to the surface that generates the quadrupole electric field (the side of the inscribed circle 3 in Figure 2) for fixing the electrodes and supplying voltage. Even with rod electrodes that have undergone precise machining, including these processes, it is difficult to reduce the deformation near the machining area to less than 2 μm relative to the diameter.

[0039] On the other hand, if the radius of the inscribed circle from the main rod inlet portion, where the pre-rods 2A-1 to 2D-1 and the main rods 2A-2 to 2D-2 are fastened together with insulating screws 4, to the main rod outlet portion, which is the end face of the main rods 2A-2 to 2D-2, becomes smaller, a decrease in the amount of ions that can pass through and a decrease in resolution will occur.

[0040] Thus, when a screw is inserted into the screw hole 5 in the fixing part of the connecting section, deformation occurs due to the torque of the screw. This deformation leads to a decrease in the sensitivity and resolution of the detected spectrum.

[0041] Figure 4 shows the spectral degradation due to deformation when the pre-rods 2A-1 to 2D-1 and main rods 2A-2 to 2D-2 are connected. In Figure 4, the lines connected by multiple black circles represent the waveforms obtained from simulation, and the lines connected by multiple triangles represent the waveforms obtained by measurement.

[0042] In the measured waveform, a knob-shaped waveform (peak) that should not normally occur is present in the portion indicated as the LD bump.

[0043] In this embodiment, taking into account the processing deformation of the rods during manufacturing, the radii of the pre-rods 2A-1 to 2D-1 are made larger than the radii of the main rods 2A-2 to 2D-2, as shown in Figures 1 and 2.

[0044] Here, the multipolar rod electrode 1 is configured such that the diameter of the inscribed circle 3 formed by the pre-rods 2A-1 to 2D-1 surrounding the ion optical axis is equal to the diameter of the inscribed circle 3 formed by the main rods 2A-2 to 2D-2 surrounding the ion optical axis, and the diameters of all the pre-rods 2A-1 to 2D-1 constituting the multipolar electrode are greater than the diameters of the main rods 2A-2 to 2D-2 connected to the pre-rods 2A-1 to 2D-1 via insulating members (insulating washers) 6.

[0045] Specifically, as shown in Figure 3, for example, the rod-facing surfaces (the surfaces on the side of the inscribed circle 3 in Figure 2) of the pre-rod 2A-1 and the main rod 2A-2 are positioned facing each other within the assembly guide jig 7. Then, gravity is used to align the lower side surfaces of the pre-rod 2A-1 and the main rod 2A-2 within the assembly guide jig 7 so that they align with the reference line RL.

[0046] This minimizes the inclination of the pre-rod 2A-1 and the difference in height between the pre-rod 2A-1 and the main rod 2A-2.

[0047] Pre-rod 2B-1 and main rod 2B-2, pre-rod 2C-1 and main rod 2C-2, and pre-rod 2D-1 and main rod 2D-2 are aligned within the assembly guide jig 7 using gravity, in the same manner as pre-rod 2A-1 and main rod 2A-2.

[0048] Figure 5 is a diagram that further explains the assembly method of the pre-rod 2A-1 and the main rod 2A-2.

[0049] In Figure 5, the end face of the main rod 2A-2 and the end face of the pre-rod 2A-1 are positioned opposite each other via the insulating member 6, and the pre-rod 2A-1 and the insulating member 6 are temporarily fixed to the main rod 2A-2 by lightly tightening them with insulating screws 4.

[0050] Then, the pre-rod 2A-1 and the main rod 2A-2 are inserted into the cylindrical assembly guide jig 7, and the positions of the pre-rod 2A-1 and the main rod 2A-2 are aligned.

[0051] In other words, gravity is used to align the lower side of the pre-rod 2A-1 and the lower side of the main rod 2A-2 within the assembly guide jig 7 so that they align with the reference line RL. This allows the pre-rod 2A-1 and the main rod 2A-2 to be positioned in the positional relationship shown in Figure 2.

[0052] Next, the resin support column (pre-rod position adjustment member) 8 is attached to the screw hole 5 on the pre-rod 2A-1 side via the pre-rod side position adjustment hole 7a formed in the assembly guide jig 7, and the assembly position adjustment jig (main rod position adjustment member) 9 is attached to the screw hole 10 on the main rod 2A-2 side via the main rod side position adjustment hole 7b formed in the assembly guide jig 7, thereby aligning the tapped hole positions of the pre-rod 2A-1 and the main rod 2A-2.

[0053] Then, using a torque driver, the screws are tightened through the resin support column 8 with a constant tightening torque, and the insulated screws 4 are tightened to secure them in place.

[0054] Next, remove the resin support column 8 and the assembly position adjustment jig 9 from the pre-rod 2A-1 and the main rod 2A-2, and remove the assembly guide jig 7 from the pre-rod 2A-1 and the main rod 2A-2.

[0055] In the case of a quadrupole rod electrode, the geometric shapes of the pre-rod electrode section and the main rod electrode section are characterized by the ratio R / r0, where R is the rod radius and r0 is the radius of the inscribed circle that touches the electrode tip. In this embodiment, the diameter 2R of the pre-rod electrode section is set to be at least 0.03% larger than the diameter 2R of the main rod electrode section.

[0056] Figure 6 shows the measured data when the diameter of pre-rods 2A-1 to 2D-1 is increased by 0.03%, with the diameter of pre-rods 2A-1 to 2D-1 being 9.5 mm and the diameter of main rods 2A-2 to 2D-2 being 9.498 mm.

[0057] The data shown in Figure 6 shows that the nodular peaks present in Figure 4 have been eliminated. The diameters of the pre-rods 2A-1 to 2D-1 are preferably 0.03% or more and 0.08% or less than the diameters of the main rods 2A-2 to 2D-2.

[0058] The multi-rod electrode 1 described above has the configuration shown in Figure 2, and since processing deformation is suppressed, linearity between the main rods 2A-2 to 2D-2 and the pre-rods 2A-1 to 2D-1 is ensured, and a decrease in the sensitivity and resolution of the detected spectrum can be suppressed.

[0059] Although a quadrupole rod electrode is shown as an example in this embodiment, the technical concept of the present invention is not limited to quadrupoles, but can also be applied to various multipole rod electrodes having a pre-rod electrode section and a main rod electrode section, such as sextupoles and octupoles.

[0060] <Mass spectrometer> The following describes a mass spectrometer in which the ion permeation section, using the multi-pole rod electrode 1 described above, functions as the ion transport section (Q0).

[0061] Figure 7 shows the configuration of the mass spectrometer 28 when the ion permeation section 37 according to this embodiment functions as the ion transport section Q0.

[0062] In Figure 7, the mass spectrometer 28 mainly consists of an ion source 29 and a vacuum chamber 30. The ion source 29 can be an ion source using APCI, ESI, or various other ionization methods.

[0063] The vacuum chamber 30 is divided into a first vacuum chamber 31, a second vacuum chamber 32, and a third vacuum chamber 33, each of which is independently evacuated by a vacuum pump (not shown), and maintained at pressure ranges of several hundred Pa or less, several Pa or less, and 0.1 Pa or less, respectively.

[0064] Ions generated in the ion source 29 pass through the first pore 34 and are introduced into the first vacuum chamber 31. Subsequently, the ions pass through the second pore 35 and are introduced into the second vacuum chamber 32. After that, the ions pass through the ion transport section Q0. The ion transport section Q0 can use the multi-pole rod electrode 1 as described above, and the method of applying voltage is basically the same, but the voltage conditions of high-frequency voltage and DC voltage are generally different compared to when it is used as the ion dissociation section Q2.

[0065] Furthermore, the inlet electrode, outlet electrode, piping 8, and case used in the ion dissociation section Q2 are not necessary.

[0066] Ions that have passed through the ion transport section Q0 pass through the third pore 36 and are introduced into the third vacuum chamber 33. Subsequently, the ions pass through the first ion separation section Q1. The first ion separation section Q1 uses a QMF consisting of four rod electrodes, which separates and allows only ions with a specific m / z from the ions introduced into the first ion separation section Q1 to pass through.

[0067] Ions of a specific m / z that have passed through the first ion separation section Q1 are introduced into the ion dissociation section Q2. Ions that have passed through the ion dissociation section Q2 are introduced into the second ion separation section Q3. The second ion separation section Q3 uses a QMF consisting of four rod electrodes, which separates and allows to pass the ions introduced into the second ion separation section Q3 according to their m / z.

[0068] Ions that have passed through the second ion separation unit Q3 are detected by the detector 40. The mass spectrometer 28 also includes a control unit 41 for receiving instructions from the user and controlling voltage, etc.

[0069] According to the present invention, linearity between the main rods 2A-2 to 2D-2 and the pre-rods 2A-1 to 2D-1 can be ensured, and a method for assembling the pre-rods 2A-1 and main rods 2A-2 of a mass spectrometer and a stationary mass spectrometer can be provided that reduces the decrease in spectral sensitivity and resolution due to deformation during the assembly of the double electrode.

[0070] In the example described above, the ion permeable section 37 was used as the ion transport section Q0. However, the ion permeable section 37 according to the present invention can also be applied to the first ion separation section Q1, the ion dissociation section Q2, and the second ion separation section Q3.

[0071] Furthermore, the present invention is applicable as long as there are multiple rod sets consisting of pre-rods and main rods.

[0072] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. [Explanation of symbols]

[0073] 1...Multi-pole rod electrode, 2A, 2B, 2C, 2D...Rod electrode, 2A-1, 2B-1, 2C-1, 2D-1...Pre-rod, 2A-2, 2B-2, 2C-2, 2D-2...Main rod, 3...Inscribed circle, 4...Insulating screw, 5...Screw hole, 6...Insulating member (insulating washer), 7...Assembly guide jig, 7a...Hole for adjusting the side position of the pre-rod, 7b...Hole for adjusting the side position of the main rod, 8...Resin support column (member for adjusting the position of the pre-rod), 9... Assembly position adjustment jig (main rod position adjustment component), 10...screw hole, 28...mass spectrometer, 30...vacuum chamber, 31...first vacuum chamber, 32...second vacuum chamber, 33...third vacuum chamber, 34...first pore, 35...second pore, 36...third pore, 37...ion permeation section, 40...detector, 41...control section, Q0...ion transport section, Q1...first ion separation section, Q2...ion dissociation section, Q3...second ion separation section, RL...reference line

Claims

1. Equipped with a multi-pole rod electrode having multiple rod sets, The aforementioned rod assembly consists of a pre-rod and a main rod connected in the direction of the ion optical axis via an insulating member. In the aforementioned multipole rod electrode, the pre-rod constitutes the pre-rod electrode section, and the main rod constitutes the main rod electrode section of the mass spectrometer, The diameter of the inscribed circle formed by the pre-rod electrode portion surrounding the ion optical axis is equal to the diameter of the inscribed circle formed by the main rod electrode portion surrounding the ion optical axis. A mass spectrometer characterized in that the diameters of all the pre-rods constituting the multi-pole rod electrode are larger than the diameter of the main rod connected to the pre-rod via the insulating member.

2. In the mass spectrometer described in claim 1, A mass spectrometer characterized in that the difference between the diameter of the pre-rod and the diameter of the main rod is 0.03% or more and 0.08% or less of the diameter of the main rod.

3. In the assembly method of the pre-rod and main rod of a mass spectrometer, The end face of the pre-rod and the end face of the main rod are placed facing each other via an insulating member, and the pre-rod, the insulating member, and the main rod are temporarily fixed together with insulating screws. Insert the pre-rod, the insulating member, and the main rod into the cylindrical assembly guide jig, and align the lower side surface of the pre-rod and the lower side surface of the main rod with the reference line. The pre-rod position adjustment member is attached to the pre-rod through the pre-rod side position adjustment hole formed in the assembly guide jig, and the main rod position adjustment member is attached to the main rod through the main rod side position adjustment hole formed in the assembly guide jig, thereby aligning the positions of the pre-rod and the main rod. The pre-rod and the main rod are fixed together. Remove the pre-rod position adjustment member and the main rod position adjustment member, Remove the assembly guide jig from the pre-rod and the main rod. A method for assembling a pre-rod and a main rod, characterized by the features described above.

4. In the method for assembling a pre-rod and a main rod according to claim 3, A method for assembling a pre-rod and a main rod, characterized in that the difference between the diameter of the pre-rod and the diameter of the main rod is 0.03% or more and 0.08% or less of the diameter of the main rod.

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