Multi-pole assembly configuration for reducing capacitive coupling

Abstract

The first multipole assembly includes a first plurality of rod electrodes arranged about an axis and configured to radially confine ions about the axis. A second multipole assembly disposed adjacent to the first multipole assembly includes a second plurality of rod electrodes disposed about the axis and configured to radially confine the ions about the axis. An orientation of the first multipole assembly about the axis is rotationally offset relative to an orientation of the second multipole assembly about the axis.

Description

[0001] This invention application is a divisional application of the invention patent application with application number 202110224101.7, application date March 1, 2021, and name “Multi-pole component configuration for reducing capacitive coupling”. Background Art

[0002] A mass spectrometer is an analytical tool that can be used for qualitative and / or quantitative analysis of a sample. A mass spectrometer typically includes: an ion source for generating ions from a sample; a mass analyzer for separating ions based on their mass-to-charge ratio; and an ion transfer device for transferring ions generated by the ion source to the mass analyzer. A mass spectrometer uses data from the mass analyzer to construct a mass spectrum that shows the relative abundance of each detected ion as a function of its mass-to-charge ratio. By analyzing the mass spectrum generated by a mass spectrometer, a user may be able to identify substances in a sample, measure the relative or absolute amounts of known components present in a sample, and / or perform structural elucidation of unknown components.

[0003] The ion transfer device and / or mass analyzer may include one or more multipole assemblies having multiple electrodes. These multipole assemblies have the function of guiding, capturing and / or filtering ions. As an example, the multipole assembly can be a quadrupole having four rod electrodes arranged in two pairs of opposing rod electrodes. Opposite phases of radio frequency (RF) voltages can be applied to the rod electrode pairs, thereby generating a quadrupole electric field that guides or captures ions in the central region of the quadrupole.

[0004] In a quadrupole mass filter, a mass-resolving direct current (DC) voltage may also be applied to the rod electrode pair, thereby superimposing a DC electric field on the quadrupole electric field and making the trajectory of some ions unstable and thereby ejecting the ions onto one of the rod electrodes. In such a mass filter, only ions with a certain mass-to-charge ratio maintain a stable trajectory and are subsequently detected by the ion detector.

[0005] When a multipole assembly is used in a mass spectrometer, the inaccurate electric field generated by the multipole assembly may result in poor ion transmission and lead to reduced resolution, sensitivity and / or mass accuracy. Summary of the invention

[0006] The following description presents a simplified overview of one or more aspects of the methods and systems described herein in order to provide a basic understanding of such aspects. This overview is not an exhaustive overview of all conceived aspects, and is neither intended to identify key or critical elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects of the methods and systems described herein in a simplified form as a prelude to the more detailed description presented below.

[0007] In some exemplary embodiments, a mass spectrometer includes: a first multipole assembly, which includes a first plurality of rod electrodes arranged around an axis and configured to radially confine ions around the axis; and a second multipole assembly, which is adjacent to the first multipole assembly and includes a second plurality of rod electrodes arranged around the axis and configured to radially confine the ions around the axis, wherein the orientation of the first multipole assembly around the axis is rotationally offset relative to the orientation of the second multipole assembly around the axis.

[0008] In some exemplary embodiments, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis so that when viewed along the axis, a rod electrode included in the first plurality of rod electrodes overlaps with two rod electrodes included in the second plurality of rod electrodes.

[0009] In some exemplary embodiments, when viewed along the axis direction, the rod electrodes included in the first plurality of rod electrodes overlap each of two rod electrodes included in the second plurality of rod electrodes by substantially the same amount.

[0010] In some exemplary embodiments, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis such that a net voltage capacitively coupled by the second plurality of rod electrodes to rod electrodes included in the first plurality of rod electrodes is approximately zero.

[0011] In some exemplary embodiments, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis so that when viewed along the axis, the rod electrodes included in the first plurality of rod electrodes do not overlap with any rod electrodes included in the second plurality of rod electrodes.

[0012] In some exemplary embodiments, the orientation of the first plurality of rod electrodes about the axis is radially offset relative to the orientation of the second plurality of rod electrodes about the axis.

[0013] In some exemplary embodiments, each of the first multipole assembly and the second multipole assembly includes an ion guide, a mass filter, an ion trap, or a collision cell.

[0014] In some exemplary embodiments, the mass spectrometer further comprises an ion source and a mass analyzer, wherein the ion source comprises the first multipole assembly and the mass analyzer comprises the second multipole assembly.

[0015] In some exemplary embodiments, the interface between the first multipole assembly and the second multipole assembly does not include a lens.

[0016] In some exemplary embodiments, the first multipole assembly and the second multipole assembly are separated by no more than about 5.0 millimeters (mm) and no less than about 0.5 mm.

[0017] In some exemplary embodiments, the first multipole assembly and the second multipole assembly are separated by no more than about 3.0 mm and no less than about 0.5 mm.

[0018] In some exemplary embodiments, a multipole assembly configured for use in a mass spectrometer includes: a first plurality of rod electrodes arranged about an axis and configured to radially confine ions about the axis, wherein the mass spectrometer includes another multipole assembly, the other multipole assembly including a second plurality of rod electrodes arranged about the axis and configured to radially confine the ions about the axis, and when the multipole assembly is positioned adjacent to the other multipole assembly in the mass spectrometer, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis.

[0019] In some exemplary embodiments, a method includes: disposing a first multipole assembly in a mass spectrometer, the first multipole assembly comprising a first plurality of rod electrodes arranged around an axis and configured to radially confine ions around the axis; and disposing a second multipole assembly adjacent to the first multipole assembly in the mass spectrometer, the second multipole assembly comprising a second plurality of rod electrodes arranged around the axis and configured to radially confine the ions around the axis, wherein the second multipole assembly is disposed in the mass spectrometer such that an orientation of the second multipole assembly around the axis is rotationally offset relative to an orientation of the first multipole assembly around the axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings illustrate various embodiments and are a part of the specification. The embodiments shown are examples only and do not limit the scope of the present disclosure. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. In addition, the drawings are not necessarily drawn to scale, as one or more elements shown in the drawings may be enlarged or adjusted to facilitate identification and discussion.

[0021] Figure 1 Functional components of an exemplary mass spectrometer system are shown.

[0022] Figure 2A Shows the Figure 1 A perspective view of an exemplary multipole assembly within a mass spectrometer system.

[0023] Figure 2B Show Figure 2A A cross-sectional view of the multipole assembly shown in FIG.

[0024] Figure 3AA functional diagram of an exemplary configuration is shown, wherein a first multipole assembly and a second multipole assembly are positioned adjacent to each other.

[0025] Figure 3B and 3C Show Figure 3A sectional views of exemplary configurations of first and second multipole assemblies shown in FIG.

[0026] Figure 4A A functional diagram of another exemplary configuration is shown, in which a first multipole assembly and a second multipole assembly are positioned adjacent to each other.

[0027] Figure 4B and 4C Show Figure 4A sectional views of exemplary configurations of first and second multipole assemblies shown in FIG.

[0028] Figure 5 exhibit Figure 4B and 4C Cross-sections superimposed on each other.

[0029] Figures 6A-6C Another exemplary configuration of a first multipole assembly and a second multipole assembly positioned adjacent to each other is shown.

[0030] Fig. 7A and 7B Additional exemplary configurations of a first multipole assembly and a second multipole assembly positioned adjacent to each other are shown.

[0031] Figure 8 Another exemplary configuration of a first multipole assembly and a second multipole assembly positioned adjacent to each other is shown.

[0032] Fig. 9 An exemplary block diagram of a method for positioning a first multipole assembly in a mass spectrometer adjacent to a second multipole assembly in the mass spectrometer is shown. DETAILED DESCRIPTION

[0033] As will be described in detail herein, a mass spectrometer includes a first multipole assembly and a second multipole assembly adjacent to the first multipole assembly. The first multipole assembly includes a first plurality of rod electrodes arranged around an axis and configured to radially confine ions around the axis. The second multipole assembly includes a second plurality of rod electrodes arranged around an axis and configured to radially confine ions around the axis. The orientation of the first multipole assembly around the axis is rotationally offset relative to the orientation of the second multipole assembly around the axis.

[0034] In some examples, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis, so that when viewed along the axis, a rod electrode included in the first plurality of rod electrodes overlaps with two rod electrodes included in the second plurality of rod electrodes. Alternatively, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis, so that when viewed along the axis, a rod electrode included in the first plurality of rod electrodes does not overlap with any rod electrode included in the second plurality of rod electrodes.

[0035] The configuration of the multipole assembly described herein can provide various benefits, including allowing the size and complexity of the mass spectrometer to be reduced without reducing the performance of the mass spectrometer. In order to reduce the size and simplify the structure of the mass spectrometer, the ion optical elements located between adjacent multipole assemblies can be removed. For example, removing the lens (e.g., the conductivity limiting lens) located in the interface between the ion transfer device and the mass analyzer can reduce the number of required voltages and drive circuits, and improve the ion transfer efficiency through these stages. However, the inventors have found that the lens located in the interface between adjacent multipole assemblies not only limits the gas conduction between the different vacuum levels of the ion source and the mass analyzer, but also protects each multipole assembly from RF coupling of the voltage applied to the multipole assembly. Such RF coupling on the multipole assembly may impair the overall performance of the mass spectrometer.

[0036] The configuration of multipole assemblies described herein allows to remove ion optics (such as lenses) from the interface between adjacent multipole assemblies, while reducing or eliminating unwanted RF coupling on the multipole assemblies. For example, compared to conventional configurations, the orientation of the first multipole assembly is offset relative to the orientation of the second multipole assembly to reduce the amount of overlap between the electrodes in the first plurality of electrodes and the second plurality of electrodes. The reduced overlap reduces the voltage that capacitively couples to the electrodes of the first and second multipole assemblies. Therefore, conductivity limiting lenses (such as Turner-Kruger lenses) can be omitted from the interface between the multipole assemblies, thereby realizing a smaller, more compact design of a mass spectrometer. In some instances, omitting conductivity limiting lenses from the interface between adjacent multipole assemblies can also increase the transmission of ions between multipole assemblies.

[0037] Various embodiments will now be described in greater detail with reference to the drawings.The exemplary systems and devices described herein may provide one or more of the benefits described above and / or various additional and / or alternative benefits that will be apparent herein.

[0038] Figure 1Functional components of an exemplary mass spectrometry system 100 ("system 100") are shown. System 100 is illustrative and not limiting. As shown, system 100 includes an ion source 102, an ion transfer device 104, a mass analyzer 106, and a controller 108.

[0039] The ion source 102 is configured to generate a plurality of ions 110 from a sample to be analyzed. The ion source 102 may use any suitable ionization technique, including but not limited to electron ionization (EI), chemical ionization (CI), matrix-assisted laser desorption / ionization (MALDI), electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), inductively coupled plasma (ICP), etc. The ion transfer device 104 may focus the ions 110 into an ion beam 112 and accelerate the ion beam 112 to the mass analyzer 106.

[0040] The mass analyzer 106 is configured to separate the ions in the ion beam 112 according to the mass-to-charge ratio of each ion. To this end, the mass analyzer 106 may include a quadrupole mass filter, an ion trap (e.g., a three-dimensional (3D) quadrupole ion trap, a cylindrical ion trap, a linear quadrupole ion trap, a circular ion trap, an orbiting ion trap, etc.), a time-of-flight (TOF) mass analyzer, an electrostatic trap mass analyzer, a Fourier transform ion cyclotron resonance (FT-ICR) mass analyzer, a sector mass analyzer, and / or any other suitable type of mass analyzer. In some examples, the multipole assembly included in the mass analyzer 106 is segmented.

[0041] In some embodiments of implementing a tandem mass spectrometer, the mass analyzer 106 and / or the ion source 102 may also include a collision cell. As used herein, the term "collision cell" is intended to encompass any structure arranged to produce product ions by a controlled dissociation process, and is not limited to a device for collision-activated dissociation. For example, the collision cell may be configured to fragment the ions using collision-induced dissociation (CID), electron transfer dissociation (ETD), electron capture dissociation (ECD), photoinduced dissociation (PID), surface induced dissociation (SID), and any other suitable technique. The collision cell may be located upstream of a mass filter that separates fragmented ions based on the mass-to-charge ratio of the ions. In some embodiments, the mass analyzer 106 may include a combination of multiple mass filters and / or collision cells, such as a triple quadrupole mass analyzer, in which the collision cell is inserted into the ion path between independently operable mass filters.

[0042] The mass analyzer 106 may further include an ion detector configured to detect the separated ions and responsively generate a signal representing the abundance of the ions. In one example, the mass analyzer 106 emits an emission beam of separated ions to an ion detector configured to detect the ions in the emission beam and generate or provide data that can be used to construct a mass spectrum of the sample. The ion detector may include, but is not limited to, an electron multiplier, a Faraday cup, and / or any other suitable detector.

[0043] The ion source 102, ion transfer device 104, and / or mass analyzer 106 may include ion optics for focusing, accelerating, and / or directing ions (e.g., ion beam 112) through the system 100. The ion optics may include, for example, ion guides, focusing lenses, deflectors, funnels, and / or any other suitable devices. For example, the ion transfer device 104 may focus the generated ions 110 into the ion beam 112, accelerate the ion beam 112, and direct the ion beam 112 toward the mass analyzer 106.

[0044] The system 100 (e.g., any one or more of the ion source 102, the ion transfer device 104, and the mass analyzer 106) may include various multipole assemblies each having a plurality of rod electrodes, as will be described in more detail below. Each such multipole assembly may, for example, form all or part of an ion transfer device, a mass analyzer (e.g., a mass filter), an ion trap, a collision cell, and / or an ion optical component (e.g., an ion guide). The multipole assembly may be coupled to an oscillating voltage power supply configured to supply an RF voltage to the plurality of rod electrodes. The multipole assembly may also be coupled to a DC power supply configured to supply, for example, a mass-resolving DC voltage to the plurality of rod electrodes.

[0045] The controller 108 may be coupled in a communication manner with the ion source 102, the ion transfer device 104, and / or the mass analyzer 106, and is configured to control the operation of the ion source, the ion transfer device, and / or the mass analyzer. The controller 108 may include hardware (e.g., a processor, a circuit system, etc.) and / or software configured to control the operation of the various components of the system 100. For example, the controller 108 may be configured to enable / disable the ion source 102. The controller 108 may also be configured to control the oscillating voltage power supply and the DC power supply to supply the RF voltage and the mass-resolving DC voltage to the multipole assembly, respectively. The controller 108 may also be configured to control the mass analyzer 106 by selecting the effective range of the mass-to-charge ratio of the ion to be detected. The controller 108 may further be configured to adjust the sensitivity of the ion detector (e.g., by adjusting the gain), or adjust the polarity of the ion detector based on the polarity of the ion being detected.

[0046] Figure 2A and 2BAn exemplary multipole assembly 200 is shown that may be used in the system 100 (eg, as an ion guide in the ion source 102 , as the ion transfer device 104 , as a mass filter in the mass analyzer 106 , as a collision cell in the mass analyzer 106 , etc.). Figure 2A A perspective view of a multi-pole assembly 200 is shown, and Figure 2B A cross-sectional view of a multipole assembly 200 is shown. The multipole assembly 200 is a quadrupole having four elongated rod electrodes 202 (e.g., a first electrode 202-1, a second electrode 202-2, a third electrode 202-3, and a fourth electrode 202-4) arranged around an axis 204 extending along the longitudinal trajectory of the electrode 202. However, it will be appreciated that the multipole assembly 200 may alternatively be configured as any other type of multipole assembly having a larger number of electrodes, such as a hexapole assembly having six electrodes, an octapole assembly having eight electrodes, or any other multipole assembly having any other suitable number of electrodes. In addition, the multipole assembly 200 may also be segmented to suit a particular embodiment.

[0047] The electrode 202 may be formed of any conductive material, such as a metal (e.g., molybdenum, nickel, titanium), a metal alloy (e.g., nickel steel, steel), and / or any other conductive material. As shown in FIG. 2 , the electrode 202 is circular (e.g., annular). However, it will be appreciated that the electrode 202 may have any other cross-sectional shape (e.g., triangular, parabolic, rectangular, elliptical, etc.) that may be suitable for a particular embodiment. The multipole assembly 200 may also include other components that may be suitable for a particular embodiment, such as a support member (not shown), to fix the electrode 202 to be substantially parallel to each other and aligned with the electrical conductor around the axis 204, and the RF voltage and / or DC voltage is supplied to the electrode 202 through the electrical conductor.

[0048] like Figure 2B As shown, the electrodes 202 are arranged as opposing electrode pairs across an axis 204. For example, a first electrode pair includes a first electrode 202-1 and a third electrode 202-3, and a second electrode pair includes a second electrode 202-2 and a fourth electrode 202-4. When the multipole assembly 200 is used in a mass spectrometry system (e.g., system 100), opposite phases of an RF voltage may be applied to the first and second pairs of electrodes 202 to generate an RF quadrupole electric field that radially confines (e.g., guides or traps) ions around the axis 204 so that the ions do not contact or discharge any of the electrodes 202. When the RF voltage oscillates, the ions are alternately attracted to the first electrode pair and the second electrode pair, thereby radially confining the ions around the axis 204.

[0049] In some embodiments, multipole assembly 200 can act as a mass-resolved multipole assembly configured to separate the ions based on their mass-to-charge ratio. Therefore, a mass-resolved DC voltage can also be applied to the electrode pair, thereby superposing a constant electric field on the RF quadrupole electric field. The constant electric field generated by the mass-resolved DC voltage causes the trajectory of the ions with a mass-to-charge ratio outside the effective stability range to become unstable, so that the unstable ions eventually discharge to one of the electrodes 202 and are not detected by the ion detector. Only ions with a mass-to-charge ratio in the effective stability range can maintain a stable trajectory and be radially restricted around axis 204 in the presence of a mass-resolved DC voltage, thereby separating such ions to be detected by the ion detector.

[0050] The quality of data generated by a mass spectrometry system using multipole assembly 200 depends on the accuracy of the RF and / or DC electric fields generated by electrodes 202. When ions in multipole assembly 200 are close to the limits of the stability range, small frequency perturbations on electrodes 202 can destabilize the ions, resulting in transmission losses and mass peak artifacts.

[0051] Figure 3A A functional diagram of a conventional configuration is shown in which a first multipole assembly 302-1 (e.g., an ion guide) and a second multipole assembly 302-2 (e.g., a mass filter) are positioned adjacent to each other end to end along an axis of the multipole assembly 302 (e.g., along axis 204). A lens 304 (e.g., a Turner-Kruger lens) is located in the interface between the multipole assemblies 302 to limit the conduction of gas from one vacuum level to another. An ion beam 306 (e.g., ion beam 112) exits the first multipole assembly 302-1 (e.g., ion transfer device 104), passes through lens 304, and then enters the second multipole assembly 302-2 (e.g., mass analyzer 106).

[0052] Figure 3B and Figure 3C Cross-sectional views of exemplary configurations of multipole assemblies 302-1 and 302-2 are shown, respectively, and the orientation of the multipole assemblies 302-1 and 302-2 relative to a common reference frame 310 is shown. As shown, the first multipole assembly 302-1 includes a first plurality of rod electrodes 308-1 through 308-4 arranged about an axis 312, and the second multipole assembly 302-2 includes a second plurality of rod electrodes 308-5 through 308-8 arranged about the axis 312. The z-axis of the reference frame 310 corresponds to the axis 312 of the multipole assemblies 302, and the x-axis and y-axis of the reference frame 310 are orthogonal to the z-axis and to each other.

[0053] As can be seen, relative to reference frame 310, the orientation of first multipole assembly 302-1 and the orientation of second multipole assembly 302-2 are substantially the same. That is, the y-axis extends through the center of electrodes 308-1, 308-3, 308-5 and 308-7, and the x-axis extends through the center of electrodes 308-2, 308-4, 308-6 and 308-8. Therefore, electrode 308-1 is located directly opposite electrode 308-5 in the z direction, and electrode 308-2 is located directly opposite electrode 308-6 in the z direction, and the rest may be deduced by analogy. Therefore, the RF voltage applied to electrodes 308-1 to 308-4 of first multipole assembly 302-1 can be capacitively coupled to electrodes 308-5 to 308-8 (and vice versa) of second multipole assembly 302-2. This coupling signal can produce undesirable transmission loss, especially when ions cross the gap between first multipole assembly 302-1 and second multipole assembly 302-2. For example, an RF voltage applied to electrode 308-1 may capacitively couple to electrode 308-5, an RF voltage applied to electrode 308-2 may capacitively couple to electrode 308-6, etc. As mentioned above, in addition to limiting the conduction of the gas, lens 304 may also shield multipole assembly 302 from such RF coupling, but lens 304 takes up space, requires drive electronics, and may also cause ion transmission losses in some cases.

[0054] Various configurations of multipole assemblies will now be described that facilitate removing lenses in the interface between adjacent multipole assemblies while substantially reducing and / or eliminating capacitive coupling between adjacent multipole assemblies.It will be appreciated that the following embodiments are exemplary only and not limiting.

[0055] Figure 4A A functional diagram of an exemplary configuration is shown in which a first multipole assembly 402-1 and a second multipole assembly 402-2 are positioned adjacent to each other end to end along an axis of the multipole assembly 402. The multipole assembly 402 may be implemented by any suitable multipole assembly described herein (e.g., the multipole assembly 200). The ion beam 404 exits the first multipole assembly 402-1 and enters the second multipole assembly 402-2. Figure 4AIn the example shown, no lens is located in the interface between the multipole assemblies 402. In the absence of an intermediate lens, the multipole assemblies 402 may be spaced no greater than about 5.0 mm and no less than about 0.5 mm. In other examples, the multipole assemblies 402 may be spaced no greater than about 3.0 mm and no less than about 0.5 mm. In other examples, the multipole assemblies 402 may be spaced no greater than about 3.0 mm and no less than about 1.0 mm. It should be noted that when the multipole assemblies 402 are spaced less than 0.5 mm, the high voltage applied to the multipole assemblies 402 may begin to break down. In an alternative example, a lens may be located in the interface between the multipole assemblies 402 to limit the conduction of the gas between different vacuum levels.

[0056] Figure 4B and 4C A cross-sectional view of an exemplary configuration of multipole assemblies 402-1 and 402-2 is shown respectively. As shown, multipole assembly 402-1 is implemented as a quadrupole having four rod electrodes 406-1 to 406-4, and multipole assembly 402-2 is also implemented as a quadrupole having four rod electrodes 406-5 to 406-8. However, multipole assembly 402 can be implemented by any other suitable multipole assembly (e.g., hexapole, octopole, etc.) that can be suitable for a specific embodiment. In addition, the first multipole assembly 402-1 and / or the second multipole assembly 402-2 can be segmented to be suitable for a specific embodiment. The segmented multipole assembly on the ion inlet side (e.g., only RF on the ion inlet side) can focus the incoming ions and reduce ion interactions, thereby reducing or even eliminating the need for conductivity limiting lenses.

[0057] Figure 4B and Figure 4C The orientation of the multipole assemblies 402 relative to each other and relative to a common reference frame 408 is shown. Figure 5 exhibit Figure 4B and 4C Cross-sections superimposed on each other. Figure 4B and 4C as well as Figure 5 As shown, the z-axis of the reference frame 408 corresponds to the axis 410 of the multipole assembly 402, and the x-axis and y-axis are orthogonal to the z-axis and to each other. The orientation of the reference frame 408 has been arbitrarily fixed based on the orientation of the electrodes 406-5 to 406-8 of the second multipole assembly 402-2. That is, the x-axis passes through the center of the electrodes 406-6 and 406-8, and the y-axis passes through the center of the electrodes 406-5 and 406-7.

[0058] As in Figure 4B and 4C as well as Figure 54, the orientation of the first multipole assembly 402-1 about the axis 410 is rotationally offset about the axis 410 relative to the orientation of the second multipole assembly 402-2 about the axis 410. For example, the orientation of the rod electrodes 406-1 to 406-4 included in the first multipole assembly 402-1 is rotationally offset about the axis 410 relative to the orientation of the rod electrodes 406-5 to 406-8 included in the second multipole assembly 402-2.

[0059] In some examples, when each electrode 406 of a pair of opposing electrodes 406 is positioned such that the center of the electrode does not overlap the center of the other electrode as viewed along axis 410, the orientation of first multipole assembly 402-1 is rotationally offset relative to the orientation of second multipole assembly 402-2.

[0060] In an additional or alternative instance, when an imaginary line passing through the center of each electrode 406 of a pair of opposing electrodes 406 included in a first multipole assembly 402-1 (or through the center of the electrode surface facing the axis 410) is not connected to an imaginary line passing through the center of each electrode 406 of a pair of opposing electrodes 406 included in a second multipole assembly 402-2 (or through the center of the electrode surface facing the axis 410), the orientation of the first multipole assembly 402-1 is rotationally offset relative to the orientation of the second multipole assembly 402-2.

[0061] For example, Figure 5 As shown, the first dashed line 502-1 passes through the centers of the opposing electrodes 406-1 and 406-3 of the first multipole assembly 402-1, and the second dashed line 502-2 passes through the centers of the opposing electrodes 406-2 and 406-4 of the first multipole assembly 402-1. Similarly, the third dashed line 502-3 (e.g., the y-axis of the reference frame 408) passes through the centers of the opposing electrodes 406-5 and 406-7 of the second multipole assembly 402-2, and the fourth dashed line 502-4 (e.g., the x-axis of the reference frame 408) passes through the centers of the opposing electrodes 406-6 and 406-8 of the second multipole assembly 402-2. Figure 5 As shown, the first multipole assembly 402-1 is rotationally offset relative to the second multipole assembly 402-2 such that the first dashed line 502-1 is not connected to the third dashed line 502-3 or the fourth dashed line 502-4.

[0062] The orientation of the first multipole assembly 402-1 about the axis 410 may be rotationally offset by any suitable amount relative to the orientation of the second multipole assembly 402-2 about the axis 410. In some examples, the offset satisfies the following relationship:

[0063]

[0064] When viewed along the z-direction, where θ is the offset angle between the dashed line of the first multipole assembly 402-1 (e.g., the first dashed line 502-1 or the second dashed line 502-2) and the nearest dashed line of the second multipole assembly 402-2 (e.g., the third dashed line 502-3 or the fourth dashed line 502-4), and n is the number of electrodes in the second multipole assembly 402-2. For example, in the case where the second multipole assembly 402-2 is a quadrupole (n=4), the offset angle θ between the first dashed line 502-1 of the first multipole assembly 402-1 and the third dashed line 502-3 of the second multipole assembly 402-2 may be greater than 0° but less than 90°. In the case where the second multipole assembly 402-2 is an octopole (n=8), the offset angle θ between the first dashed line 502-1 of the first multipole assembly 402-1 and the third dashed line 502-3 of the second multipole assembly 402-2 may be greater than 0° but less than 45°.

[0065] In some instances, the orientation of the first multipole assembly 402-1 about the axis 410 is rotationally offset relative to the orientation of the second multipole assembly 402-2 about the axis 410, such that when viewed along the axial direction (e.g., the z-direction), at least one electrode 406 (electrode 406-1) included in the first multipole assembly 402-1 overlaps with two electrodes 406 (e.g., electrodes 406-5 and 406-6) included in the second multipole assembly 402-2. Additionally or alternatively, the orientation of the first multipole assembly 402-1 about the axis 410 is rotationally offset relative to the orientation of the second multipole assembly 402-2 about the axis 410, such that when viewed along the z-direction, at least one electrode 406 (e.g., electrode 406-5) included in the second multipole assembly 402-2 overlaps with two electrodes 406 (e.g., electrodes 406-1 and 406-4) included in the first multipole assembly 402-1. With such a configuration, compared to Figures 3A-3C With the configuration, capacitive coupling across overlapping electrodes 406 included in the multi-pole assembly 402 may be reduced because capacitance is proportional to the amount of overlapping surface area.

[0066] In some examples, the orientation of the first multipole assembly 402-1 around the axis 410 is rotationally offset relative to the orientation of the second multipole assembly 402-2 around the axis 410, so that when viewed along the z-direction, at least one electrode 406 (e.g., electrode 406-1) included in the first multipole assembly 402-1 overlaps with two electrodes 406 (e.g., electrodes 406-5 and 406-6) included in the second multipole assembly 402-2 by a substantially equal amount. For example, this can be achieved by setting the offset angle θ as follows:

[0067]

[0068] exist Figure 5 In the example shown, n=4, so the offset angle θ is 45°. With such a configuration, the net voltage capacitively coupled to a single electrode 406 in a multipole assembly 402 that overlaps two electrodes 406 in another multipole assembly 402 is approximately zero. This is because the two overlapping electrodes 406 are driven by RF voltages of opposite phases, and therefore the overlapping surface areas produce equal but opposite RF displacement currents. Even though the amount of overlap is not exactly equal, compared to Figures 3A-3C configuration, the net voltage capacitively coupled to electrode 406 is also substantially reduced.

[0069] Figures 6A-6C Another exemplary configuration of multipole assemblies 402 is shown in which the orientation of a first multipole assembly 402 - 1 is rotationally offset such that none of the electrodes 406 overlap one another when viewed in the z-direction. Figures 6A-6C Respectively similar to Figure 4B , 4C 5, except that the cross-sectional surface area of ​​each electrode 406 contained in the first multipole assembly 402-1 is smaller than the gap between adjacent electrodes 406 in the second multipole assembly 402-2. Therefore, the orientation of the first multipole assembly 402-1 around the axis 410 is rotationally offset relative to the orientation of the second multipole assembly 402-2 around the axis 410, so that when viewed in the z-direction, at least one of the electrodes 406-1 to 406-4 does not overlap with any one of the electrodes 406-5 to 406-8. In this way, capacitive coupling between the multipole assemblies 402 can be completely eliminated or substantially reduced.

[0070] Fig. 7A Another exemplary configuration of a multi-pole assembly 402 is shown. Fig. 7A Similar to Figure 5 , except that, when viewed along the z-direction, at least one electrode 406 (e.g., electrode 406-1) included in the first multipole assembly 402-1 partially overlaps with only one electrode 406 (e.g., electrode 406-5) included in the second multipole assembly 402-2. With such a configuration, compared to Figures 3A-3C With the configuration, capacitive coupling on overlapping electrodes 406 included in the multi-pole assembly 402 may be reduced.

[0071] Figure 7B Another exemplary configuration of a multi-pole assembly 402 is shown. Figure 7B Similar to Figure 5 , except that, when viewed along the z direction, the electrodes 406-1 to 406-4 of the first multipole assembly 402-1 have a cross-sectional shape different from that of the electrodes 406-5 to 406-8 of the second multipole assembly 402-2. Even with electrodes 406 having different shapes, compared to Figures 3A-3CWith the configuration, capacitive coupling on overlapping electrodes 406 included in the multi-pole assembly 402 may be reduced.

[0072] In the above example, the orientation of the first multipole assembly 402-1 about the axis 410 is rotationally offset relative to the orientation of the second multipole assembly 402-2 about the axis 410. In additional or alternative embodiments, Figure 8 As shown, electrodes 406-1 through 406-4 included in the first multipole assembly 402-1 may be radially offset relative to electrodes 406-5 through 406-8 included in the second multipole assembly 402-2. Figure 8 Similar to Figure 5 , except that the electrodes 406-1 to 406-4 of the first multipole assembly 402-1 are closer to the axis 410 than the electrodes 406-5 to 406-8. That is, the distance R01 of the first multipole assembly 402-1 (i.e., the distance from the axis 410 to the nearest axis facing the electrode surface) is smaller than the distance R02 of the second multipole assembly 402-2. Figures 3A-3C Such a configuration can further reduce the amount of overlapping surface area of ​​the electrodes 406 and thereby further reduce the capacitive coupling between the electrodes 406.

[0073] In some examples, a multipole assembly (e.g., first multipole assembly 402-1) may be configured such that when the multipole assembly is disposed adjacent to another multipole assembly in a mass spectrometer, the orientation of the multipole assembly in the mass spectrometer about the axis of the multipole assembly is offset relative to the orientation of the other multipole assembly (e.g., second multipole assembly 402-2). For example, structures on the multipole assembly for mounting and installing the multipole assembly (e.g., support frame, electrical conductors, screw holes, etc.) may be specifically configured (shaped, constructed, positioned, etc.) for offset orientation.

[0074] The multipole assembly configuration described above can be readily deployed in a mass spectrometer system (eg, system 100). Fig. 9 An exemplary block diagram of a method for arranging a multipole assembly in a mass spectrometer is shown. Fig. 9 Exemplary steps according to one embodiment are shown, but other embodiments may omit, add, reorder and / or modify Fig. 9 Follow any of the steps shown in .

[0075] In step 902, a first multipole assembly is disposed in a mass spectrometer. The first multipole assembly includes a first plurality of rod electrodes arranged about an axis and configured to radially confine ions about the axis.

[0076] In step 904, a second multipole assembly is disposed adjacent to the first multipole assembly in a mass spectrometer. The second multipole assembly includes a second plurality of rod electrodes arranged around an axis and configured to radially confine ions around the axis. The second multipole assembly is disposed in the mass spectrometer such that the orientation of the second multipole assembly around the axis is rotationally offset relative to the orientation of the first multipole assembly around the axis.

[0077] Various modifications may be made to the above-described systems and configurations. For example, in the above-described configurations, the multipole assemblies have the same number of rod electrodes. However, in other configurations, the multipole assemblies may have different numbers of rod electrodes. For example, the first multipole assembly may be an octopole ion guide, and the second multipole assembly may be a quadrupole mass filter. In addition, in the above-described configurations, the first multipole assembly 402-1 is shown and described as being located upstream of the second multipole assembly 402-2. In other examples, the first multipole assembly 402-1 may be located downstream of the second multipole assembly 402-2. In yet another modification, offset orientation may be used in a series of multipole assemblies. For example, the orientation of the ion guide (Q0) may be offset relative to the orientation of the first quadrupole mass filter (Q1), the orientation of the first quadrupole mass filter (Q1) may be offset relative to the orientation of the collision cell (Q2), and the orientation of the collision cell (Q2) may be offset relative to the orientation of the second mass filter (Q3).

[0078] More generally, in the foregoing description, various exemplary embodiments have been described with reference to the accompanying drawings. However, it will be apparent that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the scope of the invention as set forth in the appended claims. For example, certain features of one embodiment described herein may be combined with or substituted for features of another embodiment described herein. Accordingly, the description and drawings should be regarded as illustrative rather than restrictive.

Claims

1. A mass spectrometer, comprising: a first multipole assembly comprising a first plurality of rod electrodes arranged about an axis and configured to radially confine ions about the axis, and a second multipole assembly adjacent to the first multipole assembly and comprising a second plurality of rod electrodes arranged about the axis and configured to radially confine the ions about the axis, wherein the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the second multipole assembly about the axis so that when viewed along the axis, a rod electrode included in the first plurality of rod electrodes overlaps two rod electrodes included in the second plurality of rod electrodes, Wherein, when viewed along the axis direction, the rod electrode included in the first plurality of rod electrodes overlaps substantially the same amount as each of the two rod electrodes included in the second plurality of rod electrodes. 2 . The mass spectrometer of claim 1 , wherein the orientation of the first plurality of rod electrodes about the axis is radially offset relative to the orientation of the second plurality of rod electrodes about the axis. 3 . The mass spectrometer of claim 1 , wherein each of the first multipole assembly and the second multipole assembly comprises an ion guide, a mass filter, an ion trap, or a collision cell.

4. The mass spectrometer according to claim 1, further comprising an ion source and a mass analyzer, The ion source includes the first multipole component, and the mass analyzer includes the second multipole component.

5. The mass spectrometer of claim 1, wherein an interface between the first multipole assembly and the second multipole assembly does not include a lens.

6. The mass spectrometer of claim 1, wherein the first multipole assembly and the second multipole assembly are separated by no more than about 5.0 mm and no less than about 0.5 mm.

7. The mass spectrometer of claim 1, wherein the first multipole assembly and the second multipole assembly are separated by no more than about 3.0 mm and no less than about 0.5 mm.

8. A multipole assembly configured for use in a mass spectrometer, the multipole assembly comprising: a first plurality of rod electrodes arranged about an axis and configured to radially confine ions about the axis, in The mass spectrometer includes another multipole assembly including a second plurality of rod electrodes arranged about the axis and configured to radially confine the ions about the axis, and When the multipole assembly is disposed adjacent to the other multipole assembly in the mass spectrometer, the orientation of the first multipole assembly about the axis is rotationally offset relative to the orientation of the other multipole assembly about the axis, so that when viewed along the axis, a rod electrode included in the first plurality of rod electrodes overlaps two rod electrodes included in the second plurality of rod electrodes, Wherein, when viewed along the axis direction, the rod electrode included in the first plurality of rod electrodes overlaps substantially the same amount as each of the two rod electrodes included in the second plurality of rod electrodes.

9. The multipole assembly of claim 8, wherein the orientation of the first plurality of rod electrodes about the axis is radially offset relative to the orientation of the second plurality of rod electrodes about the axis.

10. The multipole assembly of claim 8, wherein the multipole assembly comprises an ion guide, a mass filter, an ion trap, or a collision cell.

11. A method comprising: disposing a first multipole assembly in a mass spectrometer, the first multipole assembly comprising a first plurality of rod electrodes arranged about an axis and configured to radially confine ions about the axis; and a second multipole assembly disposed adjacent to the first multipole assembly in the mass spectrometer, the second multipole assembly comprising a second plurality of rod electrodes arranged about the axis and configured to radially confine the ions about the axis, wherein the second multipole assembly is arranged in the mass spectrometer so that the orientation of the second multipole assembly about the axis is rotationally offset relative to the orientation of the first multipole assembly about the axis so that when viewed along the axis, a rod electrode included in the second plurality of rod electrodes overlaps two rod electrodes included in the first plurality of rod electrodes, Wherein, when viewed along the axis direction, the rod electrode included in the first plurality of rod electrodes overlaps substantially the same amount as each of the two rod electrodes included in the second plurality of rod electrodes.

Images