A device capable of realizing efficient dissociation of hydrated cluster ions in an ionization source

Abstract

The application belongs to the technical field of mass spectrometry instruments, and particularly relates to a device capable of realizing efficient dissociation of hydrated cluster ions in an ionization source, which comprises a sample inlet tube, a vacuum ultraviolet lamp, an ionization source cavity, a repelling electrode, a transmission electrode group and a vacuum pump, the vacuum ultraviolet lamp, the repelling electrode and the transmission electrode group are sequentially arranged in the ionization source cavity, a direct current voltage is applied to the repelling electrode, and a direct current voltage and a radio frequency voltage are applied to the transmission electrode group. In the application, on one hand, the radio frequency electric field is used to heat the ions, and on the other hand, high-energy photoelectrons in the radio frequency electric field can collide with the hydrated cluster ions sufficiently, so that efficient dissociation of the hydrated cluster ions under high pressure is realized. In addition, the introduction of the radio frequency electric field also increases the molecular ion reaction time and further focuses the sample ions in the ionization source, improves the transmission efficiency of the sample ions, and greatly improves the detection sensitivity of the instrument.

Description

Technical Field

[0001] This invention belongs to the field of mass spectrometry analysis instrument technology, specifically a device that can achieve efficient dissociation of hydrated cluster ions within an ionization source. Background Technology

[0002] Photoionization technology based on commercially available vacuum ultraviolet lamps is an attractive soft ionization technology. Photoionization itself has advantages such as excellent ionization efficiency, high molecular ion yield and easy spectrum interpretation. Furthermore, using a simple and compact vacuum ultraviolet lamp as the light source further reduces the cost of use. Therefore, it is widely used in environmental analysis, clinical diagnosis and industrial process monitoring.

[0003] Furthermore, in photoelectric sources, selecting different reagent gases to generate reagent ions under photoelectron ionization, which then react with sample molecules (M) to induce ionization, effectively broadens the detection range of photoionization sources. However, in proton transfer reactions using water as the reagent ion, a large amount of hydrated cluster ions (H3O) are generated. + ·(H2O) n (n = 1, 2) and [MH] + ·(H2O) n (n=1, 2), which not only increases the complexity of spectral analysis but also reduces the ionization ability of reagent ions. More importantly, the proportion of cluster ions increases with the increase of ionization source pressure. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a device capable of efficiently dissociating hydrated cluster ions within an ionization source.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A device for achieving efficient dissociation of hydrated cluster ions within an ionization source includes a sample inlet tube, a vacuum ultraviolet lamp, an ionization source cavity, a repulsion electrode, a transfer electrode assembly, and a vacuum pump.

[0007] The ionization source cavity is provided with a vacuum pump port and an ion output port, and the vacuum pump port is connected to a vacuum pump.

[0008] The vacuum ultraviolet lamp, the repulsion electrode, and the transmission electrode assembly are sequentially installed inside the ionization source cavity. The light emitted from the light source of the vacuum ultraviolet lamp passes sequentially through the repulsion electrode and the transmission electrode assembly. The vacuum ultraviolet lamp is located on the side of the repulsion electrode away from the ion output port, and the transmission electrode assembly is located on the side of the repulsion electrode closer to the ion output port.

[0009] Two sample inlet tubes are provided. One end of the sample inlet tube is located outside the ionization source cavity and connected to an external water vapor source. The other end of the sample inlet tube is located outside the ionization source cavity and is used to allow sample molecules to enter the ionization source cavity through the sample inlet tube. The other ends of both sample inlet tubes are inserted into the ionization source cavity and extend to the space between the repulsion electrode and the transmission electrode group.

[0010] A DC voltage is applied to the repulsion electrode, and a DC voltage and a radio frequency voltage are applied to the transmission electrode group.

[0011] A valve is installed on the vacuum extraction port.

[0012] A mass analyzer is provided on the outside of the ionization source cavity, and the sample input end of the mass analyzer is connected to the ion output port.

[0013] The vacuum extraction port is located at the top of the ionization source cavity, and the ion output port is located on the side of the ionization source cavity. The axial center line of the vacuum extraction port is perpendicular to the horizontal plane, and the axial center line of the ion output port and the axial center line of the light source emitting end of the vacuum ultraviolet lamp are both parallel to the horizontal plane.

[0014] The axial centerlines of both sample inlet tubes are parallel to the axial centerline of the light source emitting end of the vacuum ultraviolet lamp.

[0015] The repulsion electrode is an annular plate structure with a circular through hole in the middle;

[0016] The transmission electrode assembly consists of several layers of parallel, equally spaced annular electrode sheets, each having a circular through hole, and the diameter of the circular through holes in each annular electrode sheet is equal.

[0017] All annular electrodes in the transmission electrode group have the same thickness.

[0018] The DC voltage applied to each annular electrode of the repulsive electrode and the transmission electrode group decreases sequentially along the direction of the light emitted from the light source of the vacuum ultraviolet lamp, forming a DC gradient electric field.

[0019] The peak amplitudes of the radio frequency peaks on any two adjacent annular electrodes in the transmission electrode group are equal, while their phases are opposite.

[0020] The center lines of the circular through holes of the repulsion electrode, the center lines of the circular through holes of all the annular electrodes of the transmission electrode group, the axial center line of the ion output port, and the axial center line of the light source emitting end of the vacuum ultraviolet lamp are all collinear.

[0021] The advantages and positive effects of this invention are as follows:

[0022] In this invention, on the one hand, the heating effect of the radio frequency electric field on the ions is utilized, and on the other hand, the high-energy photoelectrons in the radio frequency electric field can fully collide with the hydrated cluster ions, thereby achieving efficient dissociation of hydrated cluster ions under high pressure. In addition, the introduction of the radio frequency electric field increases the molecular ion reaction time and further focuses the sample ions in the ionization source, improving the transmission efficiency of the sample ions and greatly improving the detection sensitivity of the instrument. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] In the diagram: 1 is the sample inlet tube, 2 is the vacuum UV lamp, 3 is the ionization source chamber, 4 is the repulsion electrode, 5 is the valve, 6 is the vacuum pump, and 7 is the transfer electrode assembly. Detailed Implementation

[0025] The following is in conjunction with the appendix Figure 1 The present invention will be described in further detail below.

[0026] A device capable of efficiently dissociating hydrated cluster ions within an ionization source, such as... Figure 1 As shown, this embodiment includes a sample inlet tube 1, a vacuum ultraviolet lamp 2, an ionization source cavity 3, a repulsion electrode 4, a transfer electrode group 7, and a vacuum pump 6.

[0027] The ionization source chamber 3 is equipped with a vacuum extraction port and an ion output port, with the vacuum extraction port connected to a vacuum pump 6. The vacuum pump 6 extracts gas from the ionization source chamber 3 through the vacuum extraction port, creating a negative pressure within the chamber; the gas pressure inside the ionization source chamber 3 is typically maintained at 10-1000 Pa. The vacuum pump 6 is a commercially available product, controlled by an external controller.

[0028] A vacuum ultraviolet lamp 2, a repulsion electrode 4, and a transmission electrode assembly 7 are sequentially installed inside the ionization source cavity 3. Light emitted from the light source of the vacuum ultraviolet lamp 2 passes sequentially through the repulsion electrode 4 and the transmission electrode assembly 7. The vacuum ultraviolet lamp 2 is located on the side of the repulsion electrode 4 furthest from the ion output port, while the transmission electrode assembly 7 is located on the side of the repulsion electrode 4 closest to the ion output port. The installation structure of the vacuum ultraviolet lamp 2, the repulsion electrode 4, and the transmission electrode assembly 7 adopts existing technology. A DC voltage is applied to the repulsion electrode 4, and both a DC voltage and a radio frequency voltage are applied to the transmission electrode assembly 7.

[0029] Two sample inlet tubes 1 are provided. One end of one sample inlet tube 1 is located outside the ionization source cavity 3 and connected to an external water vapor source. The other end of the other sample inlet tube 1 is located outside the ionization source cavity 3 and is used to allow sample molecules to enter the ionization source cavity 3 through the sample inlet tube 1. The other ends of both sample inlet tubes 1 are inserted into the ionization source cavity 3 and extend to the space between the repulsion electrode 4 and the transport electrode assembly 7. The external water vapor source is provided using existing technology. One end of the other sample inlet tube 1 can be placed directly in an environment containing sample molecules, or it can be connected to a source that provides sample molecules.

[0030] Specifically, in this embodiment, a valve 5 is provided on the vacuum extraction port to control the opening and closing of the vacuum extraction port. The valve 5 is a commercially available needle valve, which is convenient to open and close.

[0031] Specifically, in this embodiment, a mass analyzer is provided on the outside of the ionization source cavity 3, and the sample input end of the mass analyzer is connected to the ion output port. The mass analyzer receives ions discharged from the ion output port for subsequent detection; the configuration of the mass analyzer is in the prior art. In this embodiment, the mass analyzer can be a commercially available time-of-flight mass analyzer, quadrupole mass analyzer, ion trap mass analyzer, sector magnetic field mass analyzer, or ion cyclotron resonance mass analyzer.

[0032] Specifically, in this embodiment, the vacuum extraction port is located at the top of the ionization source cavity 3, and the ion output port is located on the side of the ionization source cavity 3. The axial centerline of the vacuum extraction port is perpendicular to the horizontal plane, and the axial centerline of the ion output port and the axial centerline of the light source emitting end of the vacuum ultraviolet lamp 2 are both parallel to the horizontal plane. The axial centerlines of the two sample inlet tubes 1 are parallel to the axial centerline of the light source emitting end of the vacuum ultraviolet lamp 2, which is easy to manufacture and can ensure detection accuracy. In this embodiment, the vacuum ultraviolet lamp 2 can be a commercially available low-pressure inert gas discharge lamp, such as a krypton (Kr) discharge lamp, a deuterium (D2) discharge lamp, and a xenon (Xe) discharge lamp. In this embodiment, the sample inlet tube 1 can be a capillary tube made of stainless steel, quartz, or polyetheretherketone (PEEK), with an inner diameter of 50-500 μm and a length of 10-60 cm.

[0033] Specifically, in this embodiment, the repulsion electrode 4 is an annular plate structure with a circular through hole in the middle. The thickness of the repulsion electrode 4 is 1-8mm, and the diameter of the circular through hole is 2-6mm.

[0034] In this embodiment, the transmission electrode group 7 consists of six parallel, equally spaced annular electrode sheets, each with a circular through-hole. The diameter of the circular through-hole in each annular electrode sheet is equal, ranging from 8 to 20 mm. All annular electrode sheets in the transmission electrode group 7 have the same thickness, ranging from 1 to 6 mm. The materials of the repulsion electrode 4 and all annular electrode sheets in the transmission electrode group 7 can be conductive metals (such as stainless steel) or flat plates coated with a conductive metal layer. In this embodiment, the center lines of the circular through-holes of the repulsion electrode 4, the circular through-holes of all annular electrode sheets in the transmission electrode group 7, the axial center line of the ion output port, and the axial center line of the light source emitting end of the vacuum ultraviolet lamp 2 are all collinear and parallel to the horizontal plane.

[0035] Specifically, in this embodiment, the DC voltage applied to each annular electrode of the repulsion electrode 4 and the transmission electrode group 7 decreases sequentially along the direction of the light emitted from the light source of the vacuum ultraviolet lamp 2, forming a DC gradient electric field. The gradient voltage corresponding to this DC gradient electric field is 1-20V / cm. The radio frequency applied to the transmission electrode group 7 is 0.5-5MHz, and the peak-to-peak value of the radio frequency is 10-500V. The peak-to-peak values ​​of the radio frequency on any two adjacent annular electrodes in the transmission electrode group 7 are equal in amplitude and opposite in phase. The voltage setting method and the energizing method of each annular electrode of the repulsion electrode 4 and the transmission electrode group 7 adopt existing technology.

[0036] Working principle:

[0037] During operation, the sample molecules to be tested and the required water vapor enter the ionization source cavity 3 through two sample inlet tubes 1. The gas in the ionization source cavity 3 is extracted from the vacuum port by the vacuum pump 6, creating a negative pressure in the ionization source cavity 3, which allows the sample molecules (M) to be tested and the required water vapor to enter smoothly and efficiently. After the sample molecules (M) and water vapor are introduced into the ionization source cavity 3, various hydrated cluster ions will form when the water vapor content is high. By adjusting the radio frequency voltage on the transmission electrode group 7, high-energy photoelectrons collide fully with the hydrated cluster ions, thereby effectively dissociating the hydrated cluster ions and reducing the complexity of spectral analysis. In addition, the introduction of the radio frequency electric field increases the molecular ion reaction time and further focuses the sample ions in the ionization source, improving transmission efficiency and sensitivity.

Claims

1. A device for achieving efficient dissociation of hydrated cluster ions within an ionization source, characterized in that: It includes a sample inlet tube (1), a vacuum ultraviolet lamp (2), an ionization source chamber (3), a repulsion electrode (4), a transfer electrode assembly (7), and a vacuum pump (6). The ionization source cavity (3) is provided with a vacuum pump port and an ion output port, and the vacuum pump port is connected to the vacuum pump (6). The vacuum ultraviolet lamp (2), the repulsion electrode (4), and the transmission electrode group (7) are respectively installed inside the ionization source cavity (3). The light emitted from the light source emitting end of the vacuum ultraviolet lamp (2) passes through the repulsion electrode (4) and the transmission electrode group (7) respectively. The vacuum ultraviolet lamp (2) is located on the side of the repulsion electrode (4) away from the ion output port, and the transmission electrode group (7) is located on the side of the repulsion electrode (4) close to the ion output port. Two sample inlet tubes (1) are provided. One end of one sample inlet tube (1) is located outside the ionization source cavity (3) and connected to an external water vapor source. The other end of the sample inlet tube (1) is located outside the ionization source cavity (3) and is used to allow sample molecules to enter the ionization source cavity (3) through the sample inlet tube (1). The other ends of both sample inlet tubes (1) are inserted into the ionization source cavity (3) and extend to the space between the repulsion electrode (4) and the transfer electrode group (7). A DC voltage is applied to the repulsion electrode (4), and a DC voltage and a radio frequency voltage are applied to the transmission electrode group (7); The repulsion electrode (4) is an annular plate structure with a circular through hole in the middle; The transmission electrode group (7) is divided into several layers of parallel and equally spaced annular electrode sheets, each with a circular through hole. The diameter of the circular through hole of each annular electrode sheet is equal. The DC voltage applied to each annular electrode of the repulsion electrode (4) and the transmission electrode group (7) decreases sequentially along the direction of the light emitted from the light source end of the vacuum ultraviolet lamp (2) and forms a DC gradient electric field. In the transmission electrode group (7), the peak value and amplitude of the radio frequency peaks on any two adjacent annular electrodes are equal and the phases are opposite.

2. The device for achieving efficient dissociation of hydrated cluster ions within an ionization source according to claim 1, characterized in that: A valve (5) is provided on the vacuum extraction port.

3. The device for achieving efficient dissociation of hydrated cluster ions within an ionization source according to claim 1, characterized in that: A mass analyzer is provided on the outside of the ionization source cavity (3), and the sample input end of the mass analyzer is connected to the ion output port.

4. The device for achieving efficient dissociation of hydrated cluster ions within an ionization source according to claim 1, characterized in that: The vacuum extraction port is located at the top of the ionization source cavity (3), and the ion output port is located on the side of the ionization source cavity (3). The axial center line of the vacuum extraction port is perpendicular to the horizontal plane, and the axial center line of the ion output port and the axial center line of the light source emitting end of the vacuum ultraviolet lamp (2) are both parallel to the horizontal plane.

5. The device for achieving efficient dissociation of hydrated cluster ions within an ionization source according to claim 1, characterized in that: The axial center lines of the two sample inlet tubes (1) are parallel to the axial center line of the light source emitting end of the vacuum ultraviolet lamp (2).

6. The device for achieving efficient dissociation of hydrated cluster ions within an ionization source according to claim 1, characterized in that: All annular electrodes in the transmission electrode group (7) have the same thickness.

7. The device for achieving efficient dissociation of hydrated cluster ions within an ionization source according to claim 1, characterized in that: The center lines of the circular through holes of the repulsion electrode (4), the center lines of the circular through holes of all the annular electrodes of the transmission electrode group (7), the axial center line of the ion output port, and the axial center line of the light source emitting end of the vacuum ultraviolet lamp (2) are all collinear.

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