CN111883415A - Mass Analyzers for Mass Spectrometers - Google Patents

Abstract

The invention discloses a mass analyzer suitable for a mass spectrometer, comprising a non-magnetic ion drift tube made of titanium or titanium alloy material, wherein at least one grid is arranged in the non-magnetic ion drift tube, and the grid is used for Load negative voltage. The advantage of the present invention lies in that the grid arranged in the non-magnetic ion drift tube, by applying a negative voltage to the grid, attracts the positively charged sample ions entering the non-magnetic ion drift tube to improve the flight speed of the sample ions; As shown in FIG. 2 , the grid 6 is used to prevent the secondary electrons 5 sputtered from the detector 4 from entering the non-magnetic ion drift tube, so as to reduce the fluctuation and noise of the detection signal and improve the overall resolution of the mass spectrometer. By setting up multi-layer gates for layer-by-layer blocking, the influence of secondary electrons on sample ions is minimized, and the fluctuation and noise generated by the detection signal are eliminated to the greatest extent.

Description

Mass Analyzers for Mass Spectrometers

technical field

The present invention relates to time-of-flight mass spectrometers, and more particularly to mass analyzers suitable for mass spectrometers.

Background technique

In matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF MS; hereinafter referred to as mass spectrometer), the identified sample is ionized by bombarding the sample with a pulsed laser. The trajectory of the ions is controlled by the electric field, so that the ions move according to the designed path; the ions start to run from the ion source, and the ions of different masses are screened by the mass analyzer under the control of the electric field and then enter the detector, and the detector converts the electrical signals of different intensities. The corresponding spectral signals are used to distinguish the identification results.

As shown in Figure 3, the sample ion 3 obtains the initial kinetic energy from the ion source 1 and enters the mass analyzer 2 (ion drift pipe) at a very high speed to fly and drift. The time of ion flight drift is related to the ion mass-to-charge ratio m/z The square root is proportional. The larger the mass-to-charge ratio, the slower the flight speed and the longer the time to reach the detector 4. According to this principle, ions with different mass-to-charge ratios can be separated due to their different flight speeds, and arrive at the detector 4 in sequence; the longer the length L of the mass analyzer 2, the higher the resolution. However, in actual engineering practice, due to the limitation of space and processing difficulty, the length L of the mass analyzer 2 is generally between 0.5m and 1.5m, so the flight time of ions in the mass analyzer 2 is limited by the length of the mass analyzer. Ultimately, if it is necessary to continue to improve the drift time difference corresponding to ions with different mass-to-charge ratios (m/z) to improve the resolution of the mass spectrometer, only the accelerating electric field voltage U ₁ can be increased; but in engineering practice, the current The accelerating electric field voltage U ₁ has reached the ultimate strength of +20KV. At the same time, as shown in FIG. 4 , after the detector 4 is hit by ions, secondary electrons 5 will be generated and reflected back into the mass analyzer 2 , and the secondary electrons 5 with high energy will even impact the ion source 1 , which will affect the signal of the mass spectrometer. cause greater interference. Therefore, how to further improve the resolution of the mass spectrometer under the condition of being limited by the length L of the mass analyzer and the accelerating electric field voltage U ₁ is a subject of research by those skilled in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a mass analyzer suitable for a mass spectrometer, so as to improve the time resolution of the mass analyzer, thereby improving the overall resolution of the mass spectrometer.

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

The mass analyzer suitable for mass spectrometers of the present invention includes a non-magnetic ion drift tube made of titanium or titanium alloy material, and at least one grid is arranged in the non-magnetic ion drift tube, and the grid is used to load negative Voltage.

The grid is a mesh-like structure, and is arranged in the non-magnetic ion drift tube perpendicular to the flight direction of the sample ions.

There is one grid, which is arranged in the non-magnetic ion drift tube at a distance of 1 to 10 mm from the detector.

There are two grids, the first grid is arranged in the non-magnetic ion drift tube at a distance of 1 to 10 mm from the detector, and the second grid is arranged in the middle of the non-magnetic ion drift tube.

The meshes of the two grids overlap correspondingly in the flight direction of the sample ions.

The voltage loaded by the gate is -100~-1000V, and the mesh area ratio of the gate is greater than or equal to 80%.

As a preferred solution, the voltage applied to the gate is -550~-800V, and the mesh area ratio of the gate is greater than or equal to 90%.

As a preferred solution, there are multiple grids, the first grid is arranged in the non-magnetic ion drift tube at a distance of 1 to 10 mm from the detector, and the rest of the grids are arranged in the non-magnetic ion drift tube at intervals below the first gate.

The first said gate is loaded with a negative voltage; the gate below the first said gate is not loaded with a voltage.

The meshes of all the grids overlap correspondingly in the flight direction of the sample ions.

The advantage of the present invention lies in that the grid arranged in the non-magnetic ion drift tube, by applying a negative voltage to the grid, attracts the positively charged sample ions entering the non-magnetic ion drift tube to improve the flight speed of the sample ions; As shown in FIG. 2 , the grid 6 is used to prevent the secondary electrons 5 sputtered from the detector 4 from entering the non-magnetic ion drift tube, so as to reduce the fluctuation and noise of the detection signal and improve the overall resolution of the mass spectrometer. By setting up multi-layer gates for layer-by-layer blocking, the influence of secondary electrons on sample ions is minimized, and the fluctuation and noise generated by the detection signal are eliminated to the greatest extent.

Description of drawings

FIG. 1 is a schematic structural diagram of a mass spectrometer composed of a mass analyzer of the present invention.

FIG. 2 is a schematic diagram of the grid of the mass analyzer of the present invention suppressing secondary electrons.

FIG. 3 is a schematic structural diagram of a conventional mass spectrometer.

FIG. 4 is a schematic diagram of the generation of secondary electrons by a detector of a conventional mass spectrometer.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and provides detailed implementation modes and specific operation processes, but the protection scope of the present invention is not limited to the following described embodiment.

As shown in Figures 1 and 2, the mass analyzer suitable for mass spectrometers according to the present invention includes a non-magnetic ion drift tube 2.1 made of titanium or titanium alloy material, and a grid 6 is arranged in the non-magnetic ion drift tube 2.1. , the grid 6 is used to load the voltage U ₂ with the opposite polarity to the sample ion 3 . In this embodiment, the sample ions 3 are positively charged, so the gate 6 is loaded with a negative voltage U ₂ .

When in use, the sample ions 3 fly over the grid 6 at a certain speed and reach the detector 4. When the detector 4 is hit by the sample ions 3 to generate secondary electrons 5, the secondary electrons 5 are scattered to the non-magnetic ion drift tube In 2.1, when reaching the grid 6, the secondary electrons 5 are negatively charged due to the negative voltage loaded on the grid 6, so the secondary electrons 5 are repelled, thereby preventing the secondary electrons 5 from passing through the grid 6. The non-magnetic ion drift tube 2.1 flies inside to ensure the normal flight of the sample ions 3 and avoids the interference of the secondary electron 5 to the instrument detection.

In this embodiment, one grid 6 is provided, and the grid 6 selects a mesh-like structure, which is perpendicular to the flight direction of the sample ions 3 and is arranged in the non-magnetic ion drift tube 2.1 at a distance of 1~10mm from the detector 4 . Therefore, the generated secondary electrons 5 are prevented, reflected and dispersed in time, so as to prevent the secondary electrons 5 from interfering with the flight of the sample ions 3 as much as possible. The voltage U ₂ loaded on the gate 6 is selected from -100 to -1000V, preferably -550 to -800V.

Further, in order to prevent the grid 6 from blocking the passage of too many sample ions 3 and affecting the detection signal intensity of the detector 4, the mesh area ratio of the grid 6 is greater than or equal to 80%, preferably greater than or equal to 90%.

Of course, in other embodiments of the present invention, two or more grids may also be arranged in the non-magnetic ion drift tube 2.1, and the first grid 6 is arranged in the non-magnetic ion drift tube 2.1, which is connected to the detector 4. The distance is 1-10 mm, and the remaining grid spacings are arranged below the first grid 6 in the non-magnetic ion drift tube 2.1. For example, as shown in FIG. 2 , two grids are provided, and the first grid 6 is arranged in the non-magnetic ion drift tube 2.1 and the distance from the detector 4 is 1-10 mm (for example, 1.5 mm, 2 mm, 3 mm, 4 mm) , 5 mm, 6 mm, 5 mm, 8 mm, 9 mm), the second grid 7 is arranged in the middle of the non-magnetic ion drift tube 2.1. The meshes of the two grids 6 and 7 overlap correspondingly in the flight direction of the sample ions 3 , so as to prevent the sample ions 3 from being hindered too much during the flight and ensure the pass rate of the sample ions 3 . When in use, two or more grids are designed to overlap, and their meshes overlap correspondingly, so that the pass rate of sample ions 3 will not be affected due to the large number of grids. Since the secondary electrons 5 are scattered, when a small amount of secondary electrons 5 After passing through the first grid 6 due to its too large initial velocity, it flies in the non-magnetic ion drift tube 2.1 in the original flight direction, part of it hits the inner wall of the non-magnetic ion drift tube 2.1, and the other part flies to the second grid Instead, it is intercepted by the second grid 7 .

In other embodiments of the present invention, the first gate is loaded with a negative voltage; the gate under the first gate is not loaded with a voltage. The negative voltage of the first grid 6 prevents the diffusion of the secondary electrons 5 and attracts the flying sample ions. The grid below it overlaps with the mesh of the first grid, which will not affect the pass rate of the sample ions 3, and at the same time, the non-mesh portion of the grid can intercept the secondary electrons 5 flying obliquely. In this embodiment, the first grid 6 is in the shape of a metal mesh, and the grid below the grid can be made of conductive material or insulating material.

Claims (10)

1. A mass analyzer suitable for a mass spectrometer, characterized in that it comprises a non-magnetic ion drift tube made of titanium or titanium alloy material, wherein at least one grid is provided in the non-magnetic ion drift tube, and the grid For loading negative voltages. 2 . The mass analyzer suitable for a mass spectrometer according to claim 1 , wherein the grid is a mesh-like structure, and is arranged in the non-magnetic ion drift tube perpendicular to the flight direction of the sample ions. 3 . 3 . The mass analyzer suitable for mass spectrometer according to claim 2 , wherein the grid is one, which is arranged in the non-magnetic ion drift tube at a distance of 1-10 mm from the detector. 4 . 4 . The mass analyzer suitable for a mass spectrometer according to claim 2 , wherein there are two grids, and the first grid is arranged in the non-magnetic ion drift tube at a distance of 1 to 10 mm from the detector. 5 . where the second grid is arranged in the middle of the non-magnetic ion drift tube. 5. The mass analyzer suitable for a mass spectrometer according to claim 4, wherein the meshes of the two grids overlap correspondingly in the flight direction of the sample ions. 6. The mass analyzer suitable for a mass spectrometer according to any one of claims 2-5, wherein the voltage applied to the grid is -100~-1000V, and the mesh area ratio of the grid is greater than or equal to 80%. 7 . The mass analyzer suitable for a mass spectrometer according to claim 6 , wherein the voltage applied to the grid is -550~-800V, and the mesh area ratio of the grid is greater than or equal to 90%. 8 . 8 . The mass analyzer suitable for a mass spectrometer according to claim 2 , wherein there are multiple grids, and the first grid is arranged in the non-magnetic ion drift tube at a distance of 1 to 10 mm from the detector. 9 . and the rest of the grids are spaced below the first grid in the non-magnetic ion drift tube. 9 . The mass analyzer suitable for a mass spectrometer according to claim 8 , wherein: the first grid is loaded with a negative voltage; the grid below the first grid has no voltage. 10 . 10. The mass analyzer suitable for a mass spectrometer according to claim 8 or 9, wherein the meshes of all the grids are correspondingly overlapped in the flight direction of the sample ions.

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