Photoionization annular ion trap device and positive and negative ion detection method

Abstract

The invention provides a photoionization annular ion trap device and a positive and negative ion detection method. The photoionization annular ion trap device is provided with a central annular column electrode, an outer annular column electrode, a mesh electrode, an ionization source and a detector. The ionization source irradiates the annular ion trap to generate positive and negative ions. The outer ring column electrode and the center ring column electrode apply voltage to form a radial electric field, and ion radial separation is achieved. The mesh electrode has pores, allows ion emission and electric field penetration, and can apply a resonance excitation voltage during an analysis phase. The detectors on the two sides are connected with negative high voltage and positive high voltage respectively to form an electric field to achieve ion axial separation, and positive and negative ions are attracted to the corresponding detectors according to positive and negative ion charges to achieve simultaneous detection of the positive and negative ions. The device overcomes the limitation that a traditional ion trap can only detect a single ion type, and the detection efficiency is improved.

Description

Technical Field

[0001] The invention relates to an ion trap mass spectrometer, in particular to a photoionization annular ion trap device and a positive and negative ion detection method. Background Art

[0002] Mass spectrometry (MS) is an analytical tool used to analyze the composition of substances and determine molecular weight. It ionizes the sample into charged particles, and then separates and detects them according to the mass-to-charge ratio of these ions to obtain a mass spectrum.

[0003] The core structure of the annular ion trap is an electric field region similar to a ring or torus, in which ions are bound by the electric field and move along a circular path, so it has a large ion storage space. By precisely controlling the electric field parameters in the annular ion trap, the movement trajectory of the ions can be controlled.

[0004] Ultraviolet lamp ionization sources usually use the principle of photoelectric effect to generate positive ions, and obtaining positive and negative ion information of sample molecules is more conducive to analyzing the components of the analyte to be tested and meeting the application requirements of complex substance detection.

[0005] Adding high voltage to the surface of a large-area ion detector can form a flat electric field. For example, when a microchannel plate (MCP) is working, it needs to add high voltage to the surface, which will form a flat electric field.

[0006] Existing ionization sources usually produce one type of ions (positive or negative), and ion traps can only analyze a single type of ions.

[0007] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0008] The main purpose of the present invention is to solve the problems existing in the above-mentioned background technology and to provide a photoionization annular ion trap device and a positive and negative ion detection method.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A photoionization annular ion trap device, comprising:

[0011] The central annular column electrode, the outer annular column electrode and the two mesh electrodes together form an annular ion trap in which ions are captured and stored;

[0012] The ionization source irradiates the annular ion trap, ionizes the sample molecules to generate positive ions and electrons through the photoelectric effect, and at the same time, the highly electronegative compounds to be tested absorb electrons to generate negative ions, thereby achieving the simultaneous generation of positive and negative ions;

[0013] The outer ring column electrode is arranged around the central ring column electrode, and the outer ring column electrode cooperates with the central ring column electrode to apply voltage to jointly form a radial electric field of the ion trap to achieve radial separation of ions;

[0014] The two mesh electrodes are respectively located on the axial outside of the central annular column electrode and the outer annular column electrode, and have a plurality of pores for ion emission and penetration of an external electric field, and can apply a resonance excitation voltage during the scanning analysis stage;

[0015] The two detectors are located on both sides of the annular ion trap and are connected to negative high voltage and positive high voltage respectively. The electric field formed passes through the mesh electrode to achieve axial separation of positive and negative ions, and attracts positive and negative ions to the corresponding detectors according to the positive and negative charges of the ions, thereby achieving simultaneous detection of positive and negative ions.

[0016] Furthermore, the central ring column electrode and the outer ring column electrode apply high-frequency sinusoidal voltages of the same amplitude and phase during the ion capture and cooling stage, and couple a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage to form a potential difference to achieve ion capture and radial separation; the central ring column electrode and the outer ring column electrode linearly increase the amplitude of the high-frequency sinusoidal voltage over time during the scanning and analysis stage; the two mesh electrodes are connected to a 0V potential during the ion capture and cooling stage, and allow the electric field formed by the detector to pass through to affect the ion distribution in the ion trap and achieve axial separation of the ions; the two mesh electrodes also apply high-frequency sinusoidal voltages of the same amplitude and opposite phase as resonance excitation voltages during the scanning and analysis stage, so that the positive and negative ions in the ion trap are resonantly excited out of the ion trap in the order of the absolute value of the mass-to-charge ratio from small to large.

[0017] Furthermore, the ionization source is an ultraviolet lamp.

[0018] A positive and negative ion detection method uses the photoionization annular ion trap device to perform positive and negative ion detection.

[0019] Furthermore, the method comprises:

[0020] Ion capture and cooling stage: the central ring column electrode and the outer ring column electrode apply high-frequency sinusoidal voltages of the same amplitude and phase, and couple a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage to form a potential difference to achieve ion capture and radial separation; the two mesh electrodes are connected to a 0V potential; the two detectors are respectively connected to a negative high voltage and a positive high voltage, and the two mesh electrodes allow the electric field formed by the two detectors to pass through to affect the ion distribution in the ion trap and achieve axial separation of the ions;

[0021] Scanning and analysis stage: the central ring column electrode and the outer ring column electrode apply high-frequency sinusoidal voltages of the same amplitude and phase, the amplitude increases linearly with time, and couples a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage; the two mesh electrodes respectively apply high-frequency sinusoidal voltages of the same amplitude and opposite phase as resonance excitation voltages, so that the positive and negative ions in the ion trap are resonantly excited out of the ion trap in the order of the absolute value of the mass-to-charge ratio from small to large; the two detectors are respectively connected to negative high voltage and positive high voltage, and according to the positive and negative charges of the ions, the positive and negative ions are attracted to pass through the pores of the corresponding mesh electrodes to the corresponding detectors, thereby realizing simultaneous detection of positive and negative ions.

[0022] The method further comprises:

[0023] Ion removal stage: After completing a complete scan, the voltages on the central ring column electrode, the outer ring column electrode and the two mesh electrodes are unloaded, and the ions lose their restraints and are removed from the trap.

[0024] The present invention has the following beneficial effects:

[0025] The present invention provides a device and method for simultaneous separation and detection of positive and negative ions in an ionized annular ion trap, which can overcome the limitation that traditional ion traps can only detect a single type of ions (such as positive ions or negative ions) during the detection process, realize the simultaneous separation and detection of positive and negative ions, and realize comprehensive and efficient detection of ions after macromolecular cleavage or ion reaction, thereby improving the efficiency of ion detection.

[0026] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a three-dimensional diagram of an annular ion trap and a detection device according to an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of positive and negative ion separation of an annular ion trap and a detection device according to an embodiment of the present invention, wherein the black spheres are positive ion clouds and the gray spheres are negative ion clouds;

[0029] Figure 3is a schematic diagram of ion emission from a ring-shaped ion trap according to an embodiment of the present invention, wherein positive and negative ions are affected by the electric field and can only reach a detector on one side;

[0030] Figure 4 It is a timing diagram of voltage applied to each electrode of the annular ion trap according to an embodiment of the present invention.

[0031] Reference numerals: 1 is a central annular column electrode, 2 is an outer annular column electrode, 3 and 4 are mesh electrodes, 5 and 6 are detectors located at both sides of the ion trap, and 7 is an ultraviolet lamp. DETAILED DESCRIPTION

[0032] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0033] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing as well as for coupling or communication.

[0034] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0036] See also Figures 1 to 3The embodiment of the present invention provides a photoionization annular ion trap device, which can be used for simultaneous detection of positive and negative ions, including: a central annular column electrode 1, an outer annular column electrode 2 and two mesh electrodes 3 and 4, which together form an annular ion trap, and capture and store ions in the annular ion trap; an ionization source, such as an ultraviolet lamp 7, incident ultraviolet light into the annular ion trap at a set angle, ionizing the molecules of the sample to be tested to generate positive ions and electrons through the photoelectric effect, and then simultaneously generating negative ions; the outer annular column electrode 2 is arranged around the central annular column electrode 1, and the outer annular column electrode 2 cooperates with the central annular column electrode 1 to apply a voltage, and together A radial electric field of the ion trap is formed to achieve ion capture and radial separation; the two mesh electrodes 3 and 4 are respectively located on the axial outside of the central ring column electrode 1 and the outer ring column electrode 2, and have multiple pores for ion emission and penetration of the external electric field, and can apply a resonant excitation voltage in the scanning analysis stage; the two detectors 5 and 6 are respectively located on both sides of the annular ion trap and are respectively connected to negative high voltage and positive high voltage. The formed electric field passes through the mesh electrodes 3 and 4 to achieve axial separation of positive and negative ions, and attracts positive and negative ions to the corresponding detectors 5 and 6 according to the positive and negative charges of the ions, respectively, to achieve simultaneous detection of positive and negative ions.

[0037] See also Figure 4 In a preferred embodiment, the central ring column electrode 1 and the outer ring column electrode 2 apply high-frequency sinusoidal voltages of the same amplitude and phase during the ion capture and cooling stage, and couple a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage to form a potential difference to achieve ion capture and radial separation; the central ring column electrode 1 and the outer ring column electrode 2 linearly increase the amplitude of the high-frequency sinusoidal voltage over time during the scanning and analysis stage; the two mesh electrodes 3 and 4 are connected to a 0V potential during the ion capture and cooling stage, and allow the electric field formed by the detectors 5 and 6 to pass through to affect the ion distribution in the ion trap and achieve axial separation of the ions; the two mesh electrodes 3 and 4 also apply high-frequency sinusoidal voltages of the same amplitude and opposite phase as resonance excitation voltages during the scanning and analysis stage, so that the positive and negative ions in the ion trap are resonantly excited out of the ion trap in the order of the absolute value of the mass-to-charge ratio from small to large.

[0038] A positive and negative ion detection method uses the photoionization annular ion trap device to perform positive and negative ion detection.

[0039] The present invention provides a method for simultaneous separation and detection of positive and negative ions in an ionized annular ion trap, comprising an ionization source such as an ultraviolet lamp 7, a central annular column electrode 1, an outer annular column electrode 2, mesh electrodes 3, 4 and detectors 5, 6. The ultraviolet lamp 7 is incident into the annular ion trap at a specific angle, so that the sample molecules to be tested simultaneously generate positive ions and negative ions in the annular ion trap. By applying a potential difference to the annular column electrode, the positive and negative ions can be separated along the radial direction of the ion trap; at the same time, positive and negative high voltages are respectively applied to the surfaces of the detectors 5, 6 on both sides of the ion trap, and the generated electric field passes through the mesh electrodes 3, 4, so that the positive and negative ions are separated along the axial direction of the ion trap. After the positive and negative ions are separated, a high-frequency sinusoidal voltage with a phase difference of 180° is applied to the mesh electrodes 3, 4 on both sides, so that the positive and negative ions can be emitted from the trap at the same time in different directions, thereby realizing simultaneous detection of positive and negative ions.

[0040] The ultraviolet ionization source is incident at a certain angle into the annular ion trap. The sample molecules or dopant molecules generate positive ions and electrons in the annular ion trap based on the principle of the photoelectric effect. At the same time, the highly electronegative compounds to be tested absorb electrons to generate negative ions, thereby achieving the simultaneous generation of positive and negative ions.

[0041] When ions are captured and cooled, a DC voltage is coupled, and the resulting potential difference causes the positive and negative ions to separate radially.

[0042] Detectors 5 and 6 are located at both ends of the annular ion trap in the emission direction. The electric field formed can control the distribution of positive and negative ions in the ion trap through the mesh electrodes 3 and 4, and detect the corresponding ions after the ions are emitted from the trap.

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0044] Traditional three-dimensional ion traps or linear ion traps can only analyze one type of ion at a time, namely positive ions or negative ions, and cannot detect and separate positive and negative ions at the same time. The present invention provides a photoionization annular ion trap device, which can achieve storage, separation and detection of positive and negative ions by applying different voltage timing signals to each electrode of the annular ion trap and a dual detector.

[0045] In the present invention, the central ring column electrode 1, the outer ring column electrode 2, and the mesh electrodes 3 and 4 form an annular ion trap. The electric field formed by the potential difference between the central ring column electrode 1, the outer ring column electrode 2 and the detectors 5 and 6 located on both sides of the ion trap realizes the separation of positive and negative ions along the radial and axial directions.

[0046] The specific working process of the ion trap and the voltage application method are as follows:

[0047] Phase 1: Capture and Cooling Phase: The UV lamp ionization source is always on, and positive and negative ions are continuously generated in the ion trap. Figure 2 , a high-frequency alternating voltage (RF) with the same amplitude and phase is applied to the central ring column electrode 1 and the outer ring column electrode 2, and the ions are captured and stored in the annular ion trap. At the same time, a direct current constant voltage (DC) is coupled to the central ring column electrode 1 and the outer ring column electrode 2, and the mesh Electrodes 3 and 4 are connected to 0V potential. Due to the potential difference between the central ring column electrode 1 and the outer ring column electrode 2 The positive and negative ions are separated along the radial direction of the ion trap. The surface of detector 5 is connected to negative high voltage, and the surface of detector 6 is connected to positive high voltage. A small part of the electric field formed between detectors 5 and 6 enters the ion trap through mesh electrodes 3 and 4, so that the positive and negative ions are separated along the axial direction of the ion trap.

[0048] The second stage: scanning analysis stage: a high-frequency sinusoidal voltage (RF) is applied to the central ring column electrode 1 and the outer ring column electrode 2. The frequency is the same as in the first stage, but the amplitude increases linearly (sweep frequency). As in the first stage, a direct current voltage (DC) with an amplitude much lower than RF is coupled to the central ring column electrode 1 and the outer ring column electrode 2 at the same time, so that a certain potential difference is formed on the central ring column electrode 1 and the outer ring column electrode 2 to keep the positive and negative ions separated along the radial direction of the ion trap. The mesh electrodes 3 and 4 apply high-frequency sinusoidal voltages (AC) with the same amplitude and opposite phases as resonance excitation voltages. The positive and negative ions in the ion trap are resonantly excited out of the ion trap in the order of the absolute value of the mass-to-charge ratio from small to large. As in the first stage, the detectors located on both sides of the annular ion trap, the electrodes of detector 5 are connected to negative high voltage, and the electrodes of detector 6 are connected to positive high voltage. See. Figure 3 Among the charged ions leaving the annular ion trap, if the positively charged ions are emitted from the mesh electrode pores on the side close to the detector 6, they will be repelled due to the influence of the electric field force and will not be able to reach the detector; if they are emitted from the mesh electrode pores on the side close to the detector 5, the positive ions will hit the detector along the direction of the electric field and generate a signal. For the negatively charged ions, if they are emitted from the mesh electrode pores on the side close to the detector 5, they will be repelled due to the influence of the electric field force and will not be able to reach the detector; if they are emitted from the mesh electrode pores on the side close to the detector 6, the positive ions will hit the detector along the direction of the electric field and generate a signal. In this way, responses to positive and negative ions will be generated on the two detectors respectively.

[0049] The third stage: ion removal stage: After completing a complete scan, the voltage on the central ring column electrode 1, the outer ring column electrode 2, and the mesh electrodes 3 and 4 is unloaded, and the ions will lose their restraints and be removed from the trap.

[0050] In this example, the mesh electrodes 3 and 4 are mesh-shaped, allowing ions to be emitted from the pores therein, while shielding most of the electric field generated by the detectors 5 and 6, allowing only a small portion to pass through to affect the distribution of positive and negative ions.

[0051] The present invention is not limited to the orbital ion trap shown in the drawings, but may also be a polygonal trap of other shapes or a circular trap with chamfers, etc.; there is no restriction on the shape of the ion trap electrode, and the electrode may be in the form of a hyperbola, a flat plate, a cylinder, an arc or a triangle, etc.; there is no restriction on the position, length, width and shape of the electrode slit.

[0052] The present invention can solve the limitation that the ion trap can only detect a single type of ions (such as positive ions or negative ions) during the detection process, and realize comprehensive and efficient detection of ions after macromolecular cleavage or ion reaction, thereby improving the detection efficiency.

[0053] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A photoionization annular ion trap device, characterized in that: include: The central annular column electrode, the outer annular column electrode and the two mesh electrodes together form an annular ion trap in which ions are captured and stored; The ionization source irradiates the annular ion trap and uses the photoelectric effect to ionize the molecules of the sample to be tested to produce positive ions and electrons. At the same time, the highly electronegative compounds to be tested absorb electrons to produce negative ions. The outer ring column electrode is arranged around the central ring column electrode, and the outer ring column electrode cooperates with the central ring column electrode to apply voltage to jointly form a radial electric field of the ion trap to achieve radial separation of ions; The two mesh electrodes are respectively located on the axial outside of the central annular column electrode and the outer annular column electrode, and have a plurality of pores for ion emission and penetration of an external electric field, and can apply a resonance excitation voltage during the scanning analysis stage; The two detectors are located on both sides of the annular ion trap and are connected to negative high voltage and positive high voltage respectively. The electric field formed passes through the mesh electrode to achieve axial separation of positive and negative ions, and attracts positive and negative ions to the corresponding detectors according to the positive and negative charges of the ions, thereby achieving simultaneous detection of positive and negative ions.

2. The photoionization annular ion trap device according to claim 1, characterized in that: The central ring column electrode and the outer ring column electrode apply high-frequency sinusoidal voltages of the same amplitude and phase during the ion capture and cooling stages, and couple a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage to form a potential difference to achieve ion capture and radial separation; the central ring column electrode and the outer ring column electrode linearly increase the amplitude of the high-frequency sinusoidal voltage over time during the scanning analysis stage; The two mesh electrodes are connected to a 0V potential during the ion capture and cooling stages, and allow the electric field formed by the detector to pass through, thereby affecting the ion distribution in the ion trap and achieving axial separation of the ions; the two mesh electrodes also apply high-frequency sinusoidal voltages with the same amplitude and opposite phase as resonance excitation voltages during the scanning and analysis stage, so that the positive and negative ions in the ion trap are resonantly excited out of the ion trap in the order of the absolute value of the mass-to-charge ratio from small to large.

3. The photoionization annular ion trap device according to claim 1 or 2, characterized in that: The ionization source is an ultraviolet lamp.

4. A method for detecting positive and negative ions, characterized in that: The photoionization annular ion trap device as claimed in any one of claims 1 to 3 is used to detect positive and negative ions.

5. The positive and negative ion detection method according to claim 4, characterized in that: include: Ion capture and cooling stage: the central ring column electrode and the outer ring column electrode apply high-frequency sinusoidal voltages of the same amplitude and phase, and couple a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage to form a potential difference to achieve ion capture and radial separation; the two mesh electrodes are connected to a 0V potential; the two detectors are respectively connected to a negative high voltage and a positive high voltage, and the two mesh electrodes allow the electric field formed by the two detectors to pass through to affect the ion distribution in the ion trap and achieve axial separation of the ions; Scanning and analysis stage: the central ring column electrode and the outer ring column electrode apply high-frequency sinusoidal voltages of the same amplitude and phase, the amplitude increases linearly with time, and couples a DC voltage with an amplitude lower than the high-frequency sinusoidal voltage; the two mesh electrodes respectively apply high-frequency sinusoidal voltages of the same amplitude and opposite phase as resonance excitation voltages, so that the positive and negative ions in the ion trap are resonantly excited out of the ion trap in the order of the absolute value of the mass-to-charge ratio from small to large; the two detectors are respectively connected to negative high voltage and positive high voltage, and according to the positive and negative charges of the ions, the positive and negative ions are attracted to pass through the pores of the corresponding mesh electrodes to the corresponding detectors, thereby realizing simultaneous detection of positive and negative ions.

6. The positive and negative ion detection method according to claim 5, characterized in that: Also includes: Ion removal stage: After completing a complete scan, the voltages on the central ring column electrode, the outer ring column electrode and the two mesh electrodes are unloaded, and the ions lose their restraints and are removed from the trap.

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