Ion focusing method

Abstract

The invention relates to a mass spectrometry technology, and particularly provides an ion focusing method which comprises the following steps: (A1) ions sequentially pass through an incident lens, a multi-pole rod and an emergent lens; (A2) a compensation voltage E is obtained according to the mass and the charge number of the ions; and (A3) the compensation voltage E is applied to the incident lens and the emergent lens, and ions are focused at an inlet of the incident lens and an outlet of the emergent lens respectively. The invention has the advantages of good focusing effect and the like, and is applied to ion transmission.

Description

Technical Field

[0001] The present invention relates to mass spectrometry technology, and in particular to an ion focusing method. Background Art

[0002] In a triple quadrupole tandem mass spectrometer, the ion flux in the Matthew equation stability region exhibits periodicity in the transfer rod, which only contains a periodic AC potential. If the ion flux enters the transfer rod through a very small lens entrance, it will form a periodic focus in the transfer rod. This phenomenon is more pronounced when the ion flux diverges at the lens entrance. However, the velocities of ions of different mass numbers at the same ion energy vary significantly, resulting in significant differences in the focus position during ion transmission. Summary of the Invention

[0003] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides an ion focusing method.

[0004] The purpose of the present invention is achieved through the following technical solutions: An ion focusing method comprises the following steps: (A1) Ions pass through the incident lens, multipole, and exit lens in sequence; (A2) obtaining a compensation voltage E according to the mass and charge of the ions; (A3) Applying the compensation voltage E to the incident lens and the exit lens, and focusing the ions at the entrance of the incident lens and the exit of the exit lens, respectively.

[0005] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, ion energy compensation and adjustment are performed for ions of different mass numbers so that the ions are focused at the exit of the exit lens, thereby achieving greater transmission efficiency.

[0006] The use of periodic focusing differences allows the ion velocity to be controlled within a minimal voltage change range (only a few volts are required), enabling the bias voltage in the transmission rod to switch at the limit, ensuring that the focusing point appears at the next-level lens while ensuring the number of channels, thereby achieving optimal ion transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are merely used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Figure 1 is a schematic flow chart of the ion focusing method according to the present invention; Figure 2 It is a schematic diagram of the ion transport structure. DETAILED DESCRIPTION

[0008] Figure 1-Figure 2 The following description describes optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or substitutions derived from these embodiments will be within the scope of the present invention. Those skilled in the art will understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following optional embodiments, but is limited only by the claims and their equivalents.

[0009] Example 1:

[0010] An ion focusing method of this embodiment, such as Figure 1 As shown, the following steps are included.

[0011] (A1) If Figure 2 As shown, the ions 41 pass through the incident lens 11, the multipole 21 and the exit lens 31 in sequence.

[0012] (A2) Obtaining a compensation voltage E according to the mass and charge number of the ion 41 .

[0013] , .

[0014] m and q are the ion mass number and charge number, respectively; L is the distance between the inlet 111 and the outlet 311; f is the frequency of the RF voltage on the multipole 21; V is the DC voltage value on the multipole 21; r0 is the distance between the center of the multipole 21 and each pole; E0 is the reference voltage compensation value; z is the charge number; and e is the charge carried by a single electron.

[0015] (A3) The compensation voltage E is applied to the incident lens 11 and the exit lens 31 , and the ions 41 are focused at the inlet 111 of the incident lens 11 and the outlet 311 of the exit lens 31 , respectively.

[0016] Example 2:

[0017] An application example of the ion focusing method according to Example 1 of the present invention.

[0018] In this application example, Figure 2 As shown, the multipole 21 adopts a quadrupole, L=30 cm, r0=2.4 mm, f=2 MHz, E0=3 volts, and q0=0.7.

[0019] like Figure 1 As shown, the ion focusing method includes the following steps: (A1) The ions 41 pass through the incident lens 11 , the multipole 21 , and the exit lens 31 in sequence.

[0020] (A2) Obtaining a compensation voltage E according to the mass and charge number of the ion 41 .

[0021] For example, the mass of the incident ion 41 is m=490amu, q=1.6e-19C.

[0022] according to , which can ensure that the ions are focused at the exit 311 of the exit lens 31.

[0023] For example, the mass of the incident ion 41 is m=474amu, according to , which can ensure that the ions are focused at the exit 311 of the exit lens 31.

[0024] (A3) Applying the compensation voltage E to the incident lens and the exit lens, and focusing the ions at the entrance of the incident lens and the exit of the exit lens, respectively.

Claims

1. An ion focusing method comprising the following steps: (A1) Ions pass through the incident lens, multipole and exit lens in sequence; (A2) obtaining a compensation voltage E according to the mass and charge of the ions; (A3) Applying the compensation voltage E to the incident lens and the exit lens, and focusing the ions at the entrance of the incident lens and the exit of the exit lens, respectively.

2. The ion focusing method according to claim 1, characterized in that: The compensation voltage E satisfies: ， ； m and q are the ion mass number and charge number, respectively; L is the distance between the inlet and the outlet; f is the frequency of the RF voltage on the multipole; V is the DC voltage value on the multipole; r0 is the distance between the center of the multipole and each pole; E0 is the reference voltage compensation value; z is the charge number of the ion; and e is the charge carried by an electron.

3. The ion focusing method according to claim 2, characterized in that: E0=3V.

4. The ion focusing method according to claim 1, characterized in that: The multipole is a quadrupole.

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