Tripolar ion funnel device for efficient transmission of ions in wide mass range

Abstract

The invention relates to a mass spectrometer, in particular to a tripolar ion funnel device for efficient transmission of ions in a wide mass range. Comprising a fixed base, insulation supporting rods and funnel electrodes, the three funnel electrodes are arranged on the fixed base in the circumferential direction at intervals, each funnel electrode is connected with the fixed base through one insulation supporting rod, a triangular pyramid space is formed by the inner sides of the three funnel electrodes, and direct-current voltage and radio-frequency voltage are applied to the three funnel electrodes. The triangular pyramid space is used as an ion pathway; the funnel electrode comprises a plurality of stacked electrode plates, an insulating spacer is arranged between every two adjacent funnel electrode plates, and an insulating supporting rod penetrates through the funnel electrode plates and the insulating spacers which are alternately arranged. According to the invention, efficient focusing of ions in a wide mass range is realized by using the six-pole field formed by the three radio frequency voltages with the phase difference of 120 degrees, and in addition, the uniform direct-current gradient electric field can push the focused ions to be transmitted to the lower-stage vacuum, so that the sensitivity is greatly improved.

Description

Technical Field

[0001] The invention relates to a mass spectrometer, in particular to a triple ion funnel device for efficient transmission of ions in a wide mass range. Background Art

[0002] Mass spectrometry (MS) has been widely used in chemical and biological analysis due to its high sensitivity, specificity and versatility. 5 Pa) and the gas pressure between the mass analyzer (<10 -3 Pa) is very different, so it is necessary to design a differential vacuum chamber to meet the vacuum requirements. The ion paths between different vacuum chambers are often composed of Skimmer holes. After the ions are generated in the ionization source, they need to pass through several vacuum holes in succession before they can reach the mass analyzer area. In this process, a large number of ions will be intercepted by the holes, resulting in reduced sensitivity. In addition, the huge difference in high and low vacuum before and after the holes will also cause the jet to expand, causing the ion beam to diverge, further affecting the performance of the instrument.

[0003] Therefore, an efficient ion transmission system is one of the key technologies to improve the sensitivity of mass spectrometry. Currently, common ion transmission devices are mostly electrostatic lenses, multipoles, and ion funnels. The working pressure of the electrostatic lens is 10 -2 -10 -4 Pa; the multipole mainly works at 10 -2 -10Pa. To operate at a higher pressure, an additional axial electric field is required to provide thrust. The working pressure of the ion funnel is mainly between 1-1000Pa, which is suitable as an ion transmission device for transmitting ions from the ion source to the lower vacuum. During the operation of the ion funnel, the deep pseudopotential well at the exit is often easy to trap low mass-to-charge ratio ions, resulting in the inability to smoothly extract the ions, resulting in mass discrimination, which limits its application. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a tripole ion funnel device for efficient transmission of ions in a wide mass range, so as to solve the problem that ions cannot be smoothly extracted in existing ion transmission devices, resulting in mass discrimination and limiting their application.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a tripole ion funnel device for efficient transmission of ions in a wide mass range, comprising a fixed base, an insulating support rod and a funnel electrode, wherein three funnel electrodes are arranged on the fixed base at intervals along the circumferential direction, each funnel electrode is connected to the fixed base via an insulating support rod, a triangular prism space is formed on the inner sides of the three funnel electrodes, a DC voltage and a radio frequency voltage are applied to the three funnel electrodes, and the triangular prism space is used as an ion passage.

[0007] The funnel electrode comprises a plurality of stacked electrode sheets, an insulating gasket is arranged between two adjacent funnel electrode sheets, and the insulating support rod passes through the alternately placed funnel electrode sheets and each insulating gasket in sequence.

[0008] The fixed base is a flat plate structure with a central hole. The fixed base is evenly distributed with three circular through holes along the circumference, and the circular through holes are used to connect the insulating support rods.

[0009] The electrode sheet is a flat plate structure, and the shape of the flat plate structure is the remaining part after cutting off an isosceles triangle with the center angle of the circle as the vertex angle from a sector with a center angle of 120°.

[0010] A circular hole is provided on the electrode sheet near the arc edge, and the center of the circular hole is located on the vertical midline of the bottom edge of the electrode sheet.

[0011] N electrode sheets are stacked in the funnel electrode, and N≥5, and the lengths of the bottom sides of the N electrode sheets decrease from the outside to the inside.

[0012] The materials of the fixed base and the electrode sheet are conductive metal or a flat plate with a conductive metal layer plated on the surface; the insulating support rod and the insulating gasket are insulating materials.

[0013] The thickness of the fixed base is 2-4 mm, the diameter of the insulating support rod is 2-6 mm; the thickness of the electrode sheet is 0.5-1 mm, and the length of the bottom side is 2-40 mm; the thickness of the insulating gasket is 0.5-1.5 mm.

[0014] The electrode sheets in the three funnel electrodes correspond to each other one by one, and the three electrode sheets located in the same plane form an electrode group. The DC voltage applied to the three electrode sheets in each group is the same; the DC voltage applied to each electrode group decreases successively along the forward direction of the ions to form a DC gradient electric field, and the gradient voltage is 1-20V / cm; and a voltage divider resistor with the same resistance value is connected in series between two adjacent electrode groups.

[0015] A radio frequency voltage is applied to each of the funnel electrodes, and the radio frequency voltage amplitude and phase of each electrode sheet in the same column are the same; a decoupling capacitor is connected in series between two adjacent electrode sheets in the same column; the radio frequency voltage amplitudes on two adjacent funnel electrodes are the same, with a phase difference of 120°, the applied radio frequency frequency is 0.5-5MHz, and the radio frequency peak-to-peak value is 10-800V.

[0016] The advantages and beneficial effects of the present invention are as follows: the present invention utilizes a sextupole field to focus divergent ions in a wide mass range; in addition, a uniform DC gradient electric field can promote the focused ions to be transmitted to a lower vacuum level, thereby greatly improving sensitivity.

[0017] The present invention realizes efficient focusing and transmission of ions through the combination of radio frequency voltage and direct current gradient voltage: the funnel electrodes are divided into three columns, the radio frequency voltage amplitude and phase on the funnel electrodes in the same column are the same, the radio frequency voltage amplitude on the funnel electrodes in adjacent columns are the same, and the phase difference is 120°. Compared with the quadrupole field, the hexapole field can transmit a wider range of ion masses, thereby realizing a wide range of ion focusing as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an axonometric diagram of a triple ion funnel device for efficient transmission of ions in a wide mass range according to the present invention;

[0019] Figure 2 for Figure 1 A partial enlarged view of the middle part;

[0020] Figure 3 A top view of a triple ion funnel device for efficient transmission of ions in a wide mass range in the present invention;

[0021] Figure 4 It is a structural schematic diagram of the fixed base in the present invention;

[0022] Figure 5 It is a structural schematic diagram of the funnel electrode sheet in the present invention;

[0023] Figure 6 Schematic diagram of the DC voltage application method of the tripole ion funnel electrode in the present invention;

[0024] Figure 7 Schematic diagram of the method of applying radio frequency voltage to the tripole ion funnel electrode in the present invention.

[0025] In the figure: 1-fixed base, 101-center hole, 102-circular through hole, 2-insulating support rod, 3-funnel electrode, 4-insulating gasket, 5-triangular pyramid space, 6-electrode sheet, 601-circular hole, 7-gap. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] See also Figures 1 to 7As shown, the present invention provides a tripole ion funnel device for efficient transmission of ions in a wide mass range, comprising a fixed base 1, an insulating support rod 2 and a funnel electrode 3, wherein three funnel electrodes 3 are arranged on the fixed base 1 at intervals along the circumferential direction, that is, a gap 7 is provided between two adjacent funnel electrodes 3; each funnel electrode 3 is connected to the fixed base 1 through an insulating support rod 2, and a triangular prism space 5 is formed on the inner side of the three funnel electrodes 3, a DC voltage and a radio frequency voltage are applied to the three funnel electrodes 3, the triangular prism space 5 is used as an ion passage, and the area of ​​the triangular region of the triangular prism space 5 decreases successively along the advancing direction of the ions.

[0028] See also Figure 2 , Figure 3 As shown, in the embodiment of the present invention, the funnel electrode 3 includes a plurality of stacked electrode sheets 6 , an insulating gasket 4 is provided between two adjacent funnel electrode sheets 6 , and the insulating support rod 2 passes through the alternately placed funnel electrode sheets 6 and each insulating gasket 4 .

[0029] See also Figure 4 As shown, in the embodiment of the present invention, the fixed base 1 is a flat plate structure with a central hole 101 , and three circular through holes 102 are evenly distributed along the circumference of the fixed base 1 , and the circular through holes 102 are used to connect the insulating support rods 2 .

[0030] Specifically, the fixed base 1 is disc-shaped with a radius of R1; the central hole 101 on the fixed base 1 is a circular hole with a radius of R3, and its central axis coincides with the central axis of the fixed base 1; the centers of the three circular through holes 102 are located on a circle with a radius of R2, the plane of the circle with a radius of R2 coincides with the upper surface of the fixed base 1, and its center coincides with the center of the fixed base 1. The angle between the center of any two of the three circular through holes 102 and the center of the fixed base 1 is 120°, and the central axes of the three circular through holes 102 are parallel to the central axis of the fixed base 1.

[0031] Specifically, the insulating support rod 2 is a cylindrical structure, and three insulating support rods 2 are arranged at equal intervals of 120° along the circumferential direction of the fixed base 1. The central axes of the insulating support rods 2 coincide with the central axes of the circular through holes 102 on the fixed base 1, and the bottom surfaces of the three insulating support rods 2 are located on the same plane and coincide with the lower surface of the fixed base 1.

[0032] See also Figure 5 As shown, in the embodiment of the present invention, the electrode sheet 6 is a flat plate structure, and the shape of the flat plate structure is the remaining part after cutting off an isosceles triangle with the central angle as the vertex angle from a sector with a central angle of 120°. The length of the base of the isosceles triangle is L, that is, the base of the funnel electrode 3 is L, and the length of the base of each electrode sheet 6 is different.

[0033] Furthermore, a circular hole 601 is provided on the electrode sheet 6 near the edge of the circular arc, and the center of the circular hole 601 is located on the vertical midline of the bottom edge of the electrode sheet 6. The three electrode sheets 6 located in the same plane of the three funnel electrodes 3 form an electrode group, and the geometric dimensions of the three electrode sheets 6 in the group are completely consistent, the bottom edges of the three electrode sheets 6 located in the same plane form an equilateral triangle area, and the adjacent sides of the adjacent electrode sheets 6 in each group have the same vertical spacing.

[0034] In the embodiment of the present invention, N electrode sheets 6 are stacked in the funnel electrode 3, and N≥5, and the length of the bottom side of the electrode sheet 6 decreases from the outside to the inside.

[0035] In this embodiment, each funnel electrode 3 is provided with twenty-eight electrode sheets 6 arranged in parallel, and three electrode sheets 6 located in the same plane form an electrode group, thereby forming twenty-eight electrode groups. The upper surfaces of the electrode sheets 6 in each group are located in the same plane, and the difference between the electrode groups is only that the size of the bottom side L of the electrode sheet 6 is different, and the bottom sides L of the three electrode sheets 6 in each electrode group form an equilateral triangle area. The electrode groups are placed in parallel and spaced in a manner that decreases from the outside to the inside in order according to the size of the equilateral triangle formed, and the central normals of the equilateral triangles formed by all electrode groups coincide with the central axis of the fixed base 1. The area of ​​the equilateral triangle area formed by the electrode group gradually decreases with the advancing direction of the ions.

[0036] Specifically, the insulating gasket 4 is an annular through-hole structure, which is placed between any two adjacent electrode sheets 6 and between the electrode sheet 6 and the fixed base 1, and the central axis of the insulating gasket 4 coincides with the central axis of the insulating support rod 2. The circular hole 601 of the electrode sheet 6, the insulating gasket 4 and the insulating support rod 2 are coaxially arranged, and the insulating support rod 2 passes through the circular hole 601 of the electrode sheet 6 and the middle through-hole of the insulating gasket 4 for positioning the electrode.

[0037] Specifically, the thickness of the fixed base 1 is 2-4 mm, the radius R1 of the fixed base 1 is 10-40 mm, the radius R3 of the center hole 101 is 2.5-20 mm, the radius of the circular through hole 102 on the fixed base 1 is 1-3 mm, the radius R2 of the circle where the center of the circular through hole 102 is located is 8-30 mm, and R1, R2, and R3 should satisfy R1>R2>R3.

[0038] Preferably, the thickness of the fixed base 1 is 4 mm, the radius R1 of the fixed base 1 is 33 mm, the radius R3 of the center hole 101 is 15 mm, the radius of the circular through hole 102 on the fixed base 1 is 3 mm, and the radius R2 of the circle where the center of the circular through hole 102 is located is 25 mm.

[0039] Specifically, the thickness of the insulating gasket 4 is 0.5-1.5mm, and the diameter of the middle through hole is 2-6mm; the geometric dimensions of the three insulating support rods 2 are completely consistent, with a diameter of 2-6mm; the preferred diameter is 6mm; the thickness of the electrode sheet 6 is 0.5-1mm, the bottom side length is 2-40mm, and the diameter of the circular hole 601 is 2-6mm; preferably, the thickness of the electrode sheet 6 is 0.5mm, with an interval of 1mm, and the diameter of the circular hole 601 is 6mm.

[0040] Specifically, the materials of the fixed base 1 and the electrode sheet 6 are conductive metal (such as stainless steel, etc.) or a flat plate with a conductive metal layer on the surface; the insulating support rod 2 and the insulating gasket 4 are insulating materials (such as polyetheretherketone or ceramic, etc.).

[0041] Specifically, the shape of the electrode sheet 6 is not fixed, as long as the bottom side L of the electrode sheet 6 can form an equilateral triangle. The working pressure of the present invention is between 1-1000Pa; preferably, the working pressure of the integral tripole ion funnel is 500Pa.

[0042] See also Figure 3 , Figure 6 As shown, in the embodiment of the present invention, the electrode sheets 6 in the three funnel electrodes 3 correspond to each other one by one, and the three electrode sheets 6 located in the same plane form an electrode group, and the DC voltage applied to the three electrode sheets 6 in each group is the same; the DC voltage applied to each electrode group decreases successively along the forward direction of the ions to form a DC gradient electric field, and the gradient voltage is 1-20V / cm, and the preferred gradient voltage is 10V / cm; and a voltage divider resistor with the same resistance value is connected in series between two adjacent electrode groups.

[0043] See also Figure 3 , Figure 7 As shown, in the embodiment of the present invention, a radio frequency voltage is applied to each funnel electrode 3, and the amplitude and phase of the radio frequency voltage of each electrode sheet 6 in the same column are the same; a decoupling capacitor is connected in series between two adjacent electrode sheets 6 in the same column; the amplitude of the radio frequency voltage on two adjacent funnel electrodes 3 is the same, and the phase difference is 120°. The applied radio frequency frequency is 0.5-5MHz, and the radio frequency peak-to-peak value is 10-800V. Preferably, the applied radio frequency frequency is 2MHz, and the radio frequency peak-to-peak value is 600V.

[0044] The present invention provides a tripole ion funnel device for efficient transmission of ions in a wide mass range, which realizes efficient focusing and transmission of ions through a combination of radio frequency voltage and direct current gradient voltage: the funnel electrodes are divided into three columns, the radio frequency voltage amplitude and phase on the funnel electrodes in the same column are the same, and the radio frequency voltage amplitude on the funnel electrodes in adjacent columns is the same but differs in phase by 120°, thereby utilizing a sextupole field to focus divergent ions in a wide mass range; in addition, the uniform direct current gradient electric field can promote the transmission of the focused ions to a lower vacuum, thereby greatly improving the sensitivity.

[0045] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A triple ion funnel device for efficient transmission of ions in a wide mass range, characterized in that: The invention comprises a fixed base (1), an insulating support rod (2) and a funnel electrode (3), wherein three funnel electrodes (3) are arranged at intervals along the circumferential direction on the fixed base (1), each funnel electrode (3) is connected to the fixed base (1) via an insulating support rod (2), a triangular prism space (5) is formed inside the three funnel electrodes (3), a direct current voltage and a radio frequency voltage are applied to the three funnel electrodes (3), and the triangular prism space (5) is used as an ion passage.

2. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 1, characterized in that: The funnel electrode (3) comprises a plurality of stacked electrode sheets (6), an insulating gasket (4) is provided between two adjacent funnel electrode sheets (6), and the insulating support rod (2) sequentially penetrates the alternately placed funnel electrode sheets (6) and each insulating gasket (4).

3. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 2, characterized in that: The fixed base (1) is a flat plate structure with a central hole (101). Three circular through holes (102) are evenly distributed along the circumference of the fixed base (1). The circular through holes (102) are used to connect the insulating support rods (2).

4. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 2, characterized in that: The electrode sheet (6) is a flat plate structure, and the shape of the flat plate structure is the remaining part after cutting off an isosceles triangle with the center angle as the vertex angle from a sector with a center angle of 120°.

5. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 4, characterized in that: A circular hole (601) is provided on the electrode sheet (6) near the arc edge, and the center of the circular hole (601) is located on the vertical midline of the bottom edge of the electrode sheet (6).

6. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 4, characterized in that: N electrode sheets (6) are stacked in the funnel electrode (3), and N is greater than or equal to 5. The lengths of the bottom sides of the N electrode sheets (6) decrease from the outside to the inside.

7. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 2, characterized in that: The fixed base (1) and the electrode sheet (6) are made of conductive metal or a flat plate with a conductive metal layer plated on the surface; the insulating support rod (2) and the insulating gasket (4) are made of insulating material.

8. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 2, characterized in that: The thickness of the fixed base (1) is 2-4 mm, the diameter of the insulating support rod (2) is 2-6 mm; the thickness of the electrode sheet (6) is 0.5-1 mm, and the bottom side length is 2-40 mm; the thickness of the insulating gasket (4) is 0.5-1.5 mm.

9. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 2, characterized in that: The electrode sheets (6) in the three funnel electrodes (3) correspond to each other one by one, and the three electrode sheets (6) located in the same plane form an electrode group, and the three electrode sheets (6) in each group have the same DC voltage applied to them; the DC voltage applied to each electrode group decreases in sequence along the direction of ion advance, forming a DC gradient electric field, and the gradient voltage is 1-20V / cm; and a voltage divider resistor with the same resistance value is connected in series between two adjacent electrode groups.

10. The triple ion funnel device for efficient transmission of ions in a wide mass range according to claim 2, characterized in that: A radio frequency voltage is applied to each of the funnel electrodes (3), and the radio frequency voltage amplitude and phase of each of the electrode sheets (6) in the same column are the same; a decoupling capacitor is connected in series between two adjacent electrode sheets (6) in the same column; the radio frequency voltage amplitudes of two adjacent funnel electrodes (3) are the same, the phase difference is 120°, the applied radio frequency frequency is 0.5-5MHz, and the radio frequency peak-to-peak value is 10-800V.

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