Novel ion transition transmission device

Abstract

The invention discloses a novel ion transition transmission device, and belongs to the technical field of ion transmission. The inlet electrode and the outlet electrode are arranged on the two end faces of the loading cavity respectively, and a vacuum differential chamber is formed; the flight path is arranged in the vacuum differential chamber, and the octupole rod assembly is arranged on the flight path in an array mode. The octopole rod assembly is sleeved with an annular electrode assembly. The ion transmission device provided by the invention is simple in structure, high in ion transmission efficiency and capable of realizing kinetic energy modulation. Specifically, the octopole uninterruptedly transmits ions, so that the transmission quantity of the ions is ensured, and the ion transmission efficiency is ensured to the greatest extent. And an electrostatic ring electrode group is adopted to form an electric field gradient, so that the modulation effect of increasing and reducing the axial kinetic energy of charged ions is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of ion transmission, and in particular relates to a novel ion transition transmission device. Background Art

[0002] Triple quadrupole mass spectrometers are widely used in the fields of medicine, food, metabolic genetics, etc. to perform qualitative and quantitative analysis of charged ions. The ion source commonly used in LC-MS detection methods is an electrospray ion source (ESI) or an atmospheric pressure chemical ionization (APCI) ion source. Both of these ion sources work in a normal pressure atmosphere, while the working pressure environment of a quadrupole mass analyzer cannot be higher than 10 -3 Pa, so ion transmission in the vacuum transition region is a necessary part of instrument design, and the effect of ion transmission on ion kinetic energy has a crucial impact on the sensitivity and resolution of the instrument.

[0003] Ion transfer technology refers to the process of transferring ion from normal pressure atmosphere to high vacuum environment (<10 -3 Pa) is a technology for guiding and transmitting charged particles. Conventional ion transmission technologies include quadrupole radio frequency transmission, multipole radio frequency transmission, ion funnel transmission, etc. In a quadrupole transmission device, ions are transmitted inside the quadrupole with constant kinetic energy, and the kinetic energy of the ions cannot be modulated. The reason for this is that the kinetic energy of the exit ions cannot be adjusted.

[0004] The multi-pole transmission device divides the quadrupole into multiple sections, and there will be a large amount of ion loss in the transition area between adjacent quadrupoles, which will be detrimental to the transmission of ions. The ion funnel can change the kinetic energy of ions at the exit position by changing the DC electric field gradient, but the ion funnel itself is composed of multi-pole pieces, with large capacitance, and has high requirements for the RF drive power supply. Summary of the invention

[0005] In view of the problems in the related art, the present invention proposes a novel ion transition transmission device to overcome the above technical problems existing in the existing related art.

[0006] To this end, the specific technical solution adopted by the present invention is as follows: a new type of ion transition transmission device, which is suitable for ion transmission in a low-altitude environment; the ion transition transmission device comprises: a loading chamber having a predetermined length; An inlet electrode and an outlet electrode are respectively arranged on the two end surfaces of the loading cavity to form a vacuum differential chamber; An inlet through hole and an outlet through hole are respectively provided at the center of the inlet electrode and the outlet electrode to form an ion flight path; An octopole assembly, the array being on the flight path; the central axis of the octopole being parallel to the ion flight path; The annular electrode assembly is sleeved on the octopole assembly as required.

[0007] In a further embodiment, the ion transition transport device further comprises: A radio frequency power supply module is connected to the octopole assembly; wherein the radio frequency power supply module is configured to apply sinusoidal radio frequencies with the same phase to alternate rods in the octopole assembly, and to apply sinusoidal radio frequencies with opposite phases to adjacent rods; A first DC power supply module connected to the annular electrode assembly; The second DC power supply module and the third DC power supply module are connected to the inlet electrode and the outlet electrode respectively.

[0008] In a further embodiment, the octopole assembly comprises: octopoles arranged in parallel; the octopoles have a predetermined length, and gaps of predetermined lengths are respectively left between the two ends of the octopole and the inlet electrode and the outlet electrode.

[0009] In a further embodiment, the annular electrode assembly includes: n annular electrodes, which are equidistantly arranged on the octopole assembly, and n is a natural number.

[0010] In a further embodiment, the ion transition transport device further comprises: At least two groups of ceramic rings are configured to limit the octopole assembly; the at least two groups of ceramic rings are correspondingly located between two adjacent groups of annular electrodes.

[0011] In a further embodiment, the vacuum degree before the inlet electrode is defined as , the vacuum degree of the environment where the flight path is located is , the vacuum degree after the outlet electrode is , then: .

[0012] In a further embodiment, the first DC power supply module includes a voltage divider circuit configured to distribute the voltage of the annular electrode assembly at a predetermined voltage gradient.

[0013] In a further embodiment, adjacent poles are evenly distributed according to a predetermined distance.

[0014] In a further embodiment, the distance between the first annular electrode and the inlet electrode is defined as , the distance between the nth annular electrode and the entrance electrode is , the distance between other adjacent ring electrodes is , ; then there is .

[0015] In a further embodiment, the ceramic ring is made of high-purity ceramic material, and has deep platforms on both sides extending outward by a predetermined distance.

[0016] Beneficial effects of the present invention: The present invention provides an ion transmission device with a simple structure, high ion transmission efficiency and kinetic energy modulation. Specifically, the octopole continuously transmits ions, ensures the transmission amount of ions, and maximizes the ion transmission efficiency. The electrostatic ring electrode group is used to form an electric field gradient, achieving the modulation effect of increasing and decreasing the axial kinetic energy of the charged ions.

[0017] The structure design is simple, with fewer parts than the ion funnel. The requirements for RF power supply are lower, the overall load of the device is small, and the power amplifier can be driven by the RF power supply component at 10 W. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the structural diagram of the ion kinetic energy modulation transmission rod.

[0019] Figure 2 is an assembly diagram of the octopole assembly.

[0020] Figure 3 is a side view of the octopole assembly.

[0021] Figure 4 This is the power connection diagram of the ion kinetic energy modulation transmission rod.

[0022] Figures 1 to 3 The labels in the figure are: entrance electrode 1, octopole assembly 2, ring electrode assembly 3, ceramic ring 4, exit electrode 5. DETAILED DESCRIPTION

[0023] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments. They can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and advantages of the present invention.

[0024] Example 1 According to an embodiment of the present invention, a new type of ion transition transmission device is provided, which uses a simple mechanical structure to efficiently transmit ions and can fine-tune the kinetic energy of ions during ion transmission, thereby ensuring the transmission efficiency of the total amount of ions and modulating the kinetic energy of the outlet ions.

[0025] Furthermore, the novel ion transition transmission device disclosed in this embodiment is suitable for ion transmission in a low-altitude environment. Figure 1As shown, the ion transition transmission device comprises: a loading chamber with a predetermined length. An inlet electrode 1 and an outlet electrode 5 are respectively arranged on both end surfaces in the loading chamber to form a vacuum differential chamber.

[0026] Furthermore, the vacuum degree before the inlet electrode is defined as , the vacuum degree of the environment where the flight path is located is , the vacuum degree after the outlet electrode is , then: .

[0027] Combined with the diagram, the vacuum degree before the inlet electrode 1 is , then the corresponding vacuum degree of the environment where the flight path is located is is 50Pa, or below 50Pa can be 20Pa. Correspondingly, the vacuum degree after the outlet electrode is Approx. .

[0028] In this embodiment, the inlet electrode 1 and the outlet electrode 5 are discs with a diameter of 30 mm and a thickness of 0.8 mm.

[0029] An inlet hole and an outlet hole are respectively provided at the center of the inlet electrode 1 and the outlet electrode 5 to form an ion flight path. In combination with the above example, the diameter of the inlet hole and the outlet hole in this embodiment is 2 mm.

[0030] Correspondingly, there is an octopole assembly 2 arrayed on the flight path. It is worth mentioning that the central axis of the octopole is parallel to the ion flight path. Figure 2 and Figure 3 The octopole assembly 2 includes: octopoles arranged in parallel; the octopoles have a predetermined length, and gaps of predetermined lengths are respectively left between the two ends of the octopole and the entrance electrode 1 and the exit electrode 5.

[0031] For further example, the length of the octopole is 180 mm. Moreover, a predetermined gap of 2 mm is left between the two ends of the octopole and the inlet electrode 1 and the outlet electrode 5. In this embodiment, the diameter of the octopole is 5 mm.

[0032] In another embodiment, adjacent poles are evenly distributed according to a predetermined distance. In other words, the distance between the poles is 20 mm.

[0033] The novel ion transition transmission device also includes: a ring electrode assembly 3 sleeved on the octopole assembly 2 as required. In other words, the ring electrode assembly 3 is coaxial with the axis of the octopole. The ring electrode assembly 3 includes: n ring electrodes sleeved on the octopole assembly 2 at equal distances, where n is a natural number. In order to achieve uniform voltage division, the distance between the first ring electrode and the entrance electrode 1 is defined as , the distance between the nth annular electrode and the entrance electrode 1 is , the distance between other adjacent ring electrodes is , ; then there is .

[0034] In this embodiment, n=13 is used as an example, that is, 13 annular electrodes are provided. The inner diameter of the annular electrode is 14 mm, the outer diameter is 15 mm, and the thickness is 10 mm. The annular electrode at the front end is 10 mm away from the entrance electrode 1, and the 13 annular electrodes are arranged in sequence at intervals of 3 mm.

[0035] In order to better position the octopole assembly 2, the ion transition transmission device also includes: at least two groups of ceramic rings 4, which are configured to limit the octopole assembly 2; the at least two groups of ceramic rings 4 are correspondingly located between two adjacent groups of annular electrodes.

[0036] As shown in the figure, the ceramic ring 4 is a circular ring with an outer diameter of 30 mm and a thickness of 5 mm. The material is high-purity (99%) alumina. A 1 mm deep sink is set on the outer edge, which is placed exactly between the two annular electrodes. An octopole fixing arc is set inside to fix the octopole.

[0037] like Figure 4 As shown, the ion transition transmission device also includes: a radio frequency power module connected to the octopole assembly 2. The radio frequency power module is configured to apply sinusoidal radio frequencies with the same phase to the alternate rods in the octopole assembly 2, and to apply sinusoidal radio frequencies with opposite phases to adjacent rods.

[0038] It also includes: a first DC power supply module, a second DC power supply module and a third DC power supply module, which are respectively connected to the annular electrode assembly 3, the inlet electrode 1 and the outlet electrode 5.

[0039] Furthermore, a direct current of about ±0.5 V is applied at the entrance electrode 1 to converge the charged ions entering from the ion source, the inter-octopole rods apply sinusoidal radio frequency of the same phase, and the adjacent rods apply sinusoidal radio frequency of opposite phase, and the radio frequency frequency is about 1 MHz. The annular electrode assembly 3 is powered by a DC power supply, and a voltage divider circuit is used to distribute the voltage to each annular electrode with a certain voltage gradient. The exit electrode 5 applies a direct current of about ±0.5 V to converge the charged particles flying out of the octopole exit.

[0040] The modulation of ion kinetic energy depends on different ring electrode electric field gradients. The radio frequency electric field formed by the octopole ensures the radial confinement of the ions transmitted in the octopole, and the gradient electric field of the ring electrode acts to change the kinetic energy of the transmitted ions. During the acceleration of positive ions, the electric field at the entrance of the ring electrode is about 0 V, and the electric field at the exit of the ring electrode is a negative value. Each ring electrode in the middle is evenly divided to form a uniform acceleration electric field, so that the ions gain a certain amount of kinetic energy during the transmission process. During the deceleration of positive ions, the electric field at the entrance of the ring electrode is about 10 V, and the electric field at the exit of the ring electrode is a positive value greater than 10 V. Each ring electrode in the middle is evenly divided to form a uniform deceleration electric field, so that the ions attenuate a certain amount of kinetic energy during the transmission process. After leaving the octopole, the charged ions are focused by the exit electrode 5 and enter the next mass spectrometry analysis area.

Claims

1. A novel ion transition transmission device, characterized in that: The ion transition transmission device is suitable for ion transmission in a low-altitude environment; the ion transition transmission device comprises: a loading chamber having a predetermined length; An inlet electrode and an outlet electrode are respectively arranged on the two end surfaces of the loading cavity to form a vacuum differential chamber; An inlet through hole and an outlet through hole are respectively provided at the center of the inlet electrode and the outlet electrode to form an ion flight path; An octopole assembly, the array being on the flight path; the central axis of the octopole being parallel to the ion flight path; The annular electrode assembly is sleeved on the octopole assembly as required.

2. A novel ion transition transmission device according to claim 1, characterized in that: The ion transition transmission device also includes: A radio frequency power supply module is connected to the octopole assembly; wherein the radio frequency power supply module is configured to apply sinusoidal radio frequencies with the same phase to alternate rods in the octopole assembly, and to apply sinusoidal radio frequencies with opposite phases to adjacent rods; A first DC power supply module connected to the annular electrode assembly; The second DC power supply module and the third DC power supply module are connected to the inlet electrode and the outlet electrode respectively.

3. A novel ion transition transmission device according to claim 1, characterized in that: The octopole assembly comprises: octopoles arranged in parallel; the octopoles have a predetermined length, and gaps of predetermined lengths are respectively left between the two ends of the octopole and the inlet electrode and the outlet electrode.

4. A novel ion transition transmission device according to claim 1, characterized in that: The annular electrode assembly comprises: n annular electrodes, which are sleeved on the octopole assembly at equal distances, and n is a natural number.

5. A novel ion transition transmission device according to claim 4, characterized in that: The ion transition transmission device also includes: At least two groups of ceramic rings are configured to limit the octopole assembly; the at least two groups of ceramic rings are correspondingly located between two adjacent groups of annular electrodes.

6. A novel ion transition transmission device according to claim 1, characterized in that: The vacuum degree before the inlet electrode is defined as , the vacuum degree of the environment where the flight path is located is , the vacuum degree after the outlet electrode is , then: .

7. A novel ion transition transmission device according to claim 2, characterized in that: The first DC power supply module includes a voltage divider circuit configured to distribute voltage to the annular electrode assembly at a predetermined voltage gradient.

8. A novel ion transition transmission device according to claim 3, characterized in that: Adjacent poles are evenly distributed according to a predetermined distance.

9. A novel ion transition transmission device according to claim 4, characterized in that: Define the distance between the first ring electrode and the entrance electrode as , the distance between the nth annular electrode and the entrance electrode is , the distance between other adjacent ring electrodes is , ; then there is .

10. A novel ion transition transmission device according to claim 5, characterized in that: The ceramic ring is made of high-purity ceramic material, and has deep platforms extending outward by a predetermined distance on both sides.

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