Multi-electrode coordination Jinden trap with multi-port ion tank input

Abstract

The invention relates to the field of mass spectrometry, and describes a mass spectrometer based on multi-electrode coordination of a Jooden well. A multi-port ion source configured for multi-port input of electrons of ionization of gas molecules in a well and ions in an ion source outside the well, the ports being autonomously usable, comprising two external electrodes and four internal electrodes configured to excite periodic movement of ions in the well along an axis of symmetry and to detect signals caused by ions of secondary potential oscillation in the well, wherein ions are introduced into the trap from an external source with a slot, and ion movement is excited by applying an alternating voltage or the like to the electrodes. Or using a slot to introduce ions from an external source into a well in an external electrode, applying a potential to an internal electrode to create an electric field, the size of which is in a quadratic relationship with the coordinates, the electrodes having a specific equipotential surface geometry. Pulsed potentials can be applied to capture ions, multiple external ion sources can be equipped, and if the ion sources are not combined, each can be provided with a separate port. The mass spectrometer is uniquely designed in the aspects of ion input, excitation, detection, ion source configuration and the like.

Description

Technical Field

[0001] The present invention relates to the field of mass spectrometry and, in particular, describes a mass spectrometer based on various ion sources, an ion optical ion transport system, a storage linear quadrupole trap, and a multi-electrode coordinated Kimdon trap for inputting ions generated in an ion source outside the trap. This technical solution can be applied to many technical fields. Background Art

[0002] Modern mass spectrometry is a sensitive, rapid, and informative method for analyzing the atoms and molecules of substances, and it is widely used in many fields of science and technology. The identification of molecules using mass spectrometry requires high resolution to separate and identify ions of similar mass, and high precision is required to measure the mass. For a long time, Fourier transform ion cyclotron resonance (ICR) mass spectrometry has met these requirements; however, a significant disadvantage of this method is the need to use a superconducting cryogenic magnet with high (7 Tesla and above) magnetic induction, which leads to high operating costs, high size and weight of the equipment itself. Another mass spectrometer that is close to the ICR-based instrument in terms of resolution and accuracy is an instrument using the Kingdon ion trap principle (hereinafter referred to as the Kingdon trap; Kingdon, KH: A method for the neutralization of electron space charge by positive ionization at very low gas pressures (a method for neutralizing electron space charge by positive ionization at very low gas pressures). Phys. Rev. 21, 408-418 (1923)). An example of such a mass spectrometer is the common orbital ion trap, in which ions with high kinetic energy (several thousand electron volts) introduced into the ion trap are captured and stored using an electric field. This was first proposed as a mass spectrometer in the work of Knight (Knight, RD: Storage of ions from laser-produced plasmas. Appl. Phys. Lett. 38, 221-223 (1981)). Subsequently, Makarov created such a mass spectrometer and named it the Orbitrap (Eliuk, S., Makarov, A.: Evolution of Orbitrap mass spectrometry instrumentation. Annu. Rev. Anal. Chem. 8, 61-80 (2015)). In the Orbitrap, specially shaped electrodes generate an axisymmetric electrostatic field. Ions entering the field with sufficient angular momentum for capture are introduced from the outside, perpendicular to the trap axis, at a certain distance from the center of the trap. After a pulsed change in the potential of the central electrode causes a change in their angular momentum, they begin to move along a stable circular trajectory around the central electrode, while oscillating along the axis of the central electrode (the z-axis) in the quadratic potential generated by the trap electrode along the z-axis. The ions oscillate harmonically along the z-axis with a frequency inversely proportional to the square root of the ion's mass-to-charge ratio. Given that the potential has a quadratic relationship with the z-coordinate, this frequency is independent of the ion's oscillation amplitude. The quantity measured is the difference between the potentials caused by the ions moving on the external electrodes.Since the axial oscillation frequency of the ions does not depend on their energy and the electric field is set with high precision and stability, high resolution can be achieved, and the mass can be measured with high precision based on the frequency of the measured axial oscillation. Another feature of the orbital trap is that it can capture and measure the mass of a relatively large number of ions at the same time. The work of Yu.K. Golikov's team (Golikov, YK, et al., Integrated electrostatic ion traps. Appl. Phys. (Russian). 5, 50-57 (2006)) and (Nikitina, DV: Ion trap Massspectrometry in a dynamic massspectrometry. St. Petersburg doctoral dissertation (2006) [https: / / search.rsl.ru / ru / record / 01003303052]) showed that the Kingdon-Knight trap can contain multiple internal electrodes and have a quadratic dependence of the electrostatic field in the direction consistent with the direction of the internal electrodes. Analogies of our proposed multi-electrode harmonic Kimdon trap with multi-port electron and ion input are as follows: the mass spectrometer disclosed in US patent US 7989758 B2 (owned by BRUKERDALTONIK GMBH, published on August 2, 2011 IPC B01D59 / 44; H01J49 / 00), which contains a so-called Cassini trap; and the mass spectrometer based on a multi-electrode coordinated Kimdon trap disclosed in patent RU 2693570C1 (autonomous non-profit higher education organization "Skolkovo Institute of Science and Technology", published on July 3, 2019, IPC H01J 49 / 42).

[0003] The proposed technical solution aims to correct the defects of the current state of the art and differs from the prior art in that the proposed solution is configured to introduce ions through slots between external electrodes of the trap, which electrodes are used to excite the axial motion of the ions and detect the signals induced thereon by the ions involved in the axial motion. Summary of the Invention

[0004] The technical problem addressed by the claimed solution is the creation of a mass spectrometer based on a multi-electrode coordinated Golden-Trap configured to transport and capture ions generated in an ion source outside the trap, in particular ions accumulated in a storage linear quadrupole trap fed into the Golden-Trap to measure their mass.

[0005] The technical result is that the proposed solution, i.e. designing a pair of linear quadrupole trap and a Kimdon trap, can transport and capture ions generated in an ion source outside the trap more efficiently than a similar device (the Orbitrap) and accumulate them in a storage linear quadrupole trap fed into the Kimdon trap to measure their masses.

[0006] The technical result claimed is obtained by implementing a mass spectrometer based on a multi-electrode coordinated Kingdon trap, the mass spectrometer being configured for multi-port input of electrons ionized from gas molecules in the trap and of ions generated in an ion source outside the trap, wherein each port can be used autonomously and comprising two outer electrodes and four inner electrodes, symmetrically positioned, configured for exciting a periodic motion of ions in the trap along an axis of symmetry and detecting a signal caused by ions oscillating in the trap with a quadratic potential, wherein ions are introduced into the trap from an external source using a slot, which slot is located between the outer electrodes of the trap in a central plane of the trap, and in order to obtain a signal, the motion of the ions is excited in a direction of quadratic dependence of the potential on the coordinates, in particular by applying an alternating voltage to the outer electrodes forming the slot, the slot containing the ions along the direction of the oscillation frequency of the inner electrodes of the trap; or

[0007] ions are introduced into the trap from an external source using a slot, the external electrode being not located in the center plane of the trap, the ions enter a field of a secondary potential which is not at the center of the field, where the potential is minimum, but in a region above the center potential, and begin to oscillate harmonically in the secondary potential;

[0008] wherein an electric potential is applied to the inner electrodes to generate an electric field external to the electrodes, the magnitude of the electric potential being quadratically related to a coordinate along the direction of the electrodes within the trap, wherein the quadratic potential is provided by the shapes of the inner and outer electrodes, and wherein the geometry of the surface of the inner electrode is consistent with the geometry of an equipotential surface corresponding to a voltage of -0.5 to 4 kV on the inner electrode, and wherein the outer electrode has an equipotential surface geometry extending from a maximum distance of about 20 mm to about 90 mm from the center of the trap along an x-axis perpendicular to the axis of symmetry; wherein a time-distributed pulsed electric potential is applied to the inner electrodes to capture ions formed within the trap during ionization of analyte gas molecules by electrons, and wherein a time-distributed pulsed electric potential of a different shape is applied to an ion source external to the trap to capture the formed ions;

[0009] The mass spectrometer may be equipped with several ion sources located outside the Kingdon trap, whose potential U is sufficient to accelerate the ions and penetrate into the trap; if the ion sources are not combined, each type of ion source may use a separate port.

[0010] In one embodiment, the ion source is located in a vacuum chamber very close to the trap.

[0011] In one embodiment, at least one ion source is implemented outside the Kingdon ion trap using electron impact ionization, and ions are transported into the trap via ion optics, wherein the ion source may be located very close to the trap in the same vacuum chamber.

[0012] In one embodiment, at least one ion source is implemented using field ionization and the ions are transported into the trap via ion optics, where the ion source may be located very close to the trap in the same vacuum chamber.

[0013] In one embodiment, at least one ion source is implemented using field desorption, and the ions are transported to the trap via ion optics, where the ion source can be located very close to the trap in the same vacuum chamber.

[0014] In one embodiment, at least one ion source is implemented by MALDI (Matrix Assisted Laser Desorption / Ionization), and ions are transported to the trap via an ion optical system, wherein the ion source can be located very close to the trap in the same vacuum chamber.

[0015] In one embodiment, at least one ion source is implemented by electrospray and the ions are transported to the trap by ion optics.

[0016] In one embodiment, at least one ion source is implemented using one of the atmospheric ionization methods, and the ions are transported into the trap via an ion optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The following is a description of embodiments of the present invention based on the accompanying drawings, which are used to illustrate the nature of the present invention and in no way limit the scope of the present invention.

[0018] Figure 1 A multi-electrode Kimdon trap is shown in which four external ion sources are located directly outside the ion trap.

[0019] Figure 2 Shown is a multi-electrode Kimdon trap with an ion cell input from an external ion source with field desorption (in two projections) and field ionization.

[0020] Figure 3 A multi-electrode Kimdon trap with an ion sink input from an external quadrupole via an intermediate pump chamber system is shown.

[0021] Figure 4 A multi-electrode Kimdon trap with ion channel input from an external quadrupole is shown in 3D format. DETAILED DESCRIPTION

[0022] The following detailed disclosure of the embodiments of the present invention provides many details of the embodiments to ensure a clear understanding of the present invention. However, it is obvious to those skilled in the art how to use the present invention regardless of these details of the embodiments. In other cases, in order to avoid overly complicating the understanding of the features of the present invention, well-known methods, procedures, and components have not been described in detail.

[0023] Furthermore, the above presentation will clearly show that the present invention is not limited to the embodiments presented. For those skilled in the art, many potential modifications, changes, variations and substitutions that retain the essence and form of the present invention will be apparent.

[0024] To better understand the present invention, the following are some terms used in the description of the present invention. In the description of the present invention, the terms "including" and "comprising" are to be interpreted as "including but not limited to." These terms should not be interpreted as "consisting only of." Unless otherwise specified, technical and scientific terms in this application have the standard meanings generally accepted in scientific and technical literature.

[0025] Like the Orbital Trap, the multi-electrode coordinated Kindergarten trap is a pulsed device used to measure ion masses. In the case of ionization at atmospheric pressure and moderate vacuum (electrospray, MALDI, and other methods), before introducing the ions into the multi-electrode coordinated Kindergarten trap for analysis, it is necessary to accumulate the ions in a separate storage trap and then pulse them into the measurement trap. Radiofrequency ion traps, such as three-dimensional Paul traps (3D Paul traps) or linear quadrupole traps, can be used for this purpose. In the Orbital Trap, a so-called C-trap is used for this purpose. This is a curved quadrupole that focuses the ions ejected from it into a circular aperture in a vacuum chamber connecting the C-trap and the analytical trap, and then uses transfer ion optics to further transfer the ions into the analytical trap. Since ions can be introduced into the multi-electrode Kindergarten trap through a slot rather than just a circular aperture, there is no need to use a Paul trap or curved quadrupole (C-trap) to focus the ions to a single point. Instead, short linear quadrupoles are used, with their centrally centered ion assembly focused into the slot between the outer electrodes of the Kindergarten trap. This simplifies the design of the system for focusing and transferring ions from the storage trap to the analytical trap. Figure 3 and Figure 4 ).

[0026] Simulations of ion transport from the storage trap to the analysis trap showed capture efficiencies ranging from 10% to 60%, and experiments showed that ions, once formed and trapped in the trap, have lifetimes exceeding 1,000 milliseconds.

[0027] Ions can be introduced from the storage trap into the analytical trap not only in the center, but also in a manner similar to that used in the orbital trap. To achieve this, an additional slot is fabricated on the outer electrodes of the analytical trap. When ions are introduced through the slot in the central plane of the analytical trap, to receive a signal, it is necessary to stimulate ion motion in a direction that reflects the quadratic dependence of the potential on one of the coordinates, specifically along the inner electrodes of the trap. When introduced through a slot not located in the central plane of the analytical trap, the ions enter a quadratic potential field that is not at its center, where the potential is minimum, but in a region above the central potential, where they begin to oscillate harmonically within this quadratic potential. When the ions are introduced into the center, their motion within this quadratic potential must be stimulated by applying an AC voltage to the outer or inner electrodes of the trap at a frequency that matches the resonant frequency of the ions' harmonic oscillations in the quadratic field. To achieve this, the electrodes must be cut along the perpendicular symmetry plane. The voltage amplitude is adjusted experimentally to maximize ion signal amplitude and resolution. To selectively excite ions of a specific mass, the SWIFT method can be used, similar to FT ICR mass spectrometry. However, the method for generating the excitation signal differs because the ion oscillation frequency in the Kimdon trap is inversely proportional to the square root of the ion mass, while in FT ICR, it is inversely proportional to the ion mass. This method involves synthesizing a spectrum whose transformation produces a time signal of the desired frequency and amplitude to excite ions within a specific mass range or ions of a specific mass. The programmed SWIFT time signal is supplied from the DAC to the excitation electrode via an amplifier. Any type of ion source can be used to input ions externally to the Kimdon trap, allowing for the ionization of gaseous, liquid, and solid substances.

[0028] The four-electrode symmetrical coordinated Kimdon trap has four planes extending between the individual inner electrodes where ions and electrons can be introduced into the trap ( Figure 1 and Figure 2 ). These planes are equivalent. For this reason, such a trap can be used with several types of ion sources in one mass spectrometer. These may include sources with ionization inside the trap, such as sources with electron impact and sources with laser photoionization. These may also be sources with ionization outside the trap, such as sources with field desorption and field ionization, MALDI sources, electrospray sources, and any other source that ionizes at atmospheric pressure.

[0029] The mass spectrometer is implemented based on a multi-electrode coordinated Kingdon trap and is configured as a multi-port input for electrons ionized from gas molecules in the trap and ions generated in an ion source outside the trap. In this technical solution, each port can be used independently. The present invention comprises two symmetrically positioned external electrodes and four internal electrodes. The external electrodes are configured for excitation and are used to excite the periodic motion of ions in the trap along the axis of symmetry, as well as to detect signals caused by ions oscillating with a quadratic potential in the trap. A potential is applied to the internal electrodes to generate an electric field outside these electrodes, the potential of which is quadratically dependent on the coordinates of the internal electrodes about the trap axis. The quadratic properties of the potential are provided by the shapes of the internal and external electrodes. The geometry of the internal electrode surface is consistent with the geometry of the equipotential surface corresponding to a voltage of -4kV (or close to this value) on the internal electrode (this voltage determines the oscillation frequency of the ions along the z-axis and can vary from -500V to -10kV in the case of positive ions, and can vary within the same positive polarity voltage range in the case of negative ions). The outer electrode has the geometry of an equipotential surface and extends from approximately 20 mm to 90 mm from the center of the trap along the X-axis perpendicular to the symmetry axis. A pulsed potential with a specific time profile is applied to the inner electrode to capture ions formed within the trap during the ionization of analyte gas molecules by electrons, and a pulsed potential of a different shape is applied to the ion source outside the trap to capture ions formed in the ion source outside the trap.

[0030] The mass spectrometer can be equipped with several ion sources located outside the Kingdon trap, with a positive potential U sufficient to accelerate the ions and allow them to penetrate the trap. It should be noted that if the ion sources are not combined (e.g., MALDI and electrospray sources using an ion funnel), a separate port is used for each type of ion source.

[0031] Ions can be generated by field ionization methods; field desorption; matrix-assisted laser desorption / ionization (MALDI); electrospray, and by one of the atmospheric ionization methods. An ion source that does not require a low vacuum can be located very close to the trap in the same vacuum chamber.

[0032] Well field and electrode shape. In the proposed solution, the inner electrodes are spaced along the surfaces of the cube and positioned symmetrically. The inner electrodes are formed by equipotential surfaces corresponding to a voltage of approximately -4 kV, while the outer electrodes are formed by equipotential surfaces extending from the well center in the X direction from approximately 20 mm to 90 mm.

[0033] The dimensions of the trap electrodes are defined by the need to achieve the highest possible precision during the manufacturing process. The axial oscillation frequency of the trap is determined by the voltage applied to the internal electrodes. The surface area to be processed should not exceed 200 mm x 200 mm x 100 mm, which is the volume of the working area of ​​the most precise milling machine. The larger the machine's working area, the greater the effects of thermal expansion, and, all other things being equal, the lower the manufacturing precision. The proposed technical solution allows ions to be introduced into the trap from multiple directions.

[0034] Figure 1 A schematic diagram of a multi-electrode Kildon trap is shown, with four external ion sources positioned directly on the outer body of the configured ion trap, with an ion channel input trap configured into the trap. The left half of the figure shows the Kildon trap in X,Y projection (section Z = 0), and the right half of the figure shows the Kildon trap in Y,Z projection (section X = 0). Ion source 1 - Field desorption ionization with Gateway 1. Ion source 2 - Field ionization. Ion source 3 - Matrix-assisted laser desorption / ionization (MALDI) with Gateway 2. Ion source 4 - Thermal ionization with Gateway 3.

[0035] Figure 2 A schematic diagram of a multi-electrode Kildon trap is shown, with two external ion sources located directly on the outer body of the ion trap, equipped with ion channel inputs to the trap. The first source is field desorption, and the second is field ionization. The left half of the figure shows the Kildon trap in X, Y projection (section Z = 0), while the right half of the figure shows the Kildon trap with field desorption sources in Y, Z projection (section X = 0). Ion source 1—field desorption ionization equipped with Gateway 1. Ion source 2—field ionization.

[0036] Figure 3 and Figure 4 Shown is a multi-electrode Kindergarten trap with an ion channel input from an outer quadrupole via an intermediate pumping chamber system. Ions are introduced into the trap through the channels between the outer electrodes; the intermediate chamber systems are connected to each other using channel interfaces. The left half of the figure shows the Kindergarten trap in X,Y projection (Z = 0 section), while the right half shows the Kindergarten trap in Y,Z projection (X = 0 section).

[0037] Although the present invention has been described with reference to the disclosed embodiments, it will be understood by those skilled in the art that the specific experiments described in detail are only for illustrative purposes and should not be interpreted as limiting the scope of the present invention in any way. It should be understood that various modifications can be made without departing from the essence of the present invention.

Claims

1. A mass spectrometer based on a multi-electrode coordinated Kindon trap, the mass spectrometer being configured for multi-port input of electrons ionized from gas molecules in the trap and ions generated in an ion source outside the trap, wherein each port can be used autonomously and comprising two symmetrically positioned outer electrodes and four inner electrodes, configured for exciting a periodic motion of ions in the trap along an axis of symmetry and detecting a signal caused by ions oscillating with a quadratic potential in the trap, wherein ions are introduced into the trap from an external source using a slot, the slot being located between the outer electrodes of the trap in a central plane of the trap, and in order to obtain a signal, the motion of the ions is excited in a direction of a quadratic dependence of the potential on the coordinates, in particular by applying an alternating voltage to the outer electrodes to form a slot containing the ions along the direction of the oscillation frequency of the ions along the inner electrodes of the trap; or Ions are introduced into the trap from an external source using a slot located in one of the external electrodes, which is not located in the central plane of the trap, the ions enter a field of a secondary potential which is not at its center, where the potential is minimum, but in a region above the central potential, and begin to oscillate harmonically in this secondary potential; in, applying an electric potential to the inner electrodes to generate an electric field external to the electrodes, the magnitude of the electric potential being quadratically related to a coordinate along the direction of the electrodes within the trap, wherein the quadratic potential is provided by the shapes of the inner and outer electrodes, the geometry of the inner electrode surface being consistent with the geometry of an equipotential surface corresponding to a voltage of -0.5 to 4 kV on the inner electrode, and the outer electrode having an equipotential surface geometry extending from a maximum distance of about 20 mm to about 90 mm from the center of the trap along an x-axis perpendicular to the axis of symmetry; wherein a time-distributed pulsed electric potential is applied to the inner electrodes to capture ions formed within the trap during ionization of analyte gas molecules by electrons, and a time-distributed pulsed electric potential of a different shape is applied to an ion source external to the trap to capture the formed ions; The mass spectrometer may be equipped with several ion sources located outside the Kingdon trap, whose potential U is sufficient to accelerate the ions and penetrate into the trap; if the ion sources are not combined, each type of ion source may use a separate port.

2. The mass spectrometer according to claim 1, wherein The ion source is located in a vacuum chamber very close to the trap.

3. The mass spectrometer according to claim 1, wherein At least one ion source is implemented outside the Kingdon ion trap using electron impact ionization, and ions are transported into the trap via an ion optical system, wherein the ion source can be located very close to the trap in the same vacuum chamber.

4. The mass spectrometer according to claim 1, wherein At least one ion source is implemented using field ionization and field desorption, and the ions are transported to a trap via ion optics, where the ion source can be located very close to the trap in the same vacuum chamber.

5. The mass spectrometer according to claim 1, wherein At least one ion source is implemented using field desorption, and the ions are transported to a trap via ion optics, where the ion source can be located very close to the trap in the same vacuum chamber.

6. The mass spectrometer according to claim 1, characterized in that At least one ion source is realized by MALDI (Matrix Assisted Laser Desorption / Ionization) and the ions are transported to the trap by an ion optical system, wherein the ion source can be located very close to the trap in the same vacuum chamber.

7. The mass spectrometer according to claim 1, wherein At least one ion source is realized by electrospray, and the ions are transported to the trap by ion optics.

8. The mass spectrometer according to claim 1, wherein At least one ion source is implemented using one of the atmospheric ionization methods, and the ions are transported into the trap through an ion optical system.

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