CN-121983499-A - Oxygen atom induced dissociation device and method based on photoionization source

CN121983499ACN 121983499 ACN121983499 ACN 121983499ACN-121983499-A

Abstract

The invention relates to the technical field of mass spectrometry analysis instruments, in particular to an oxygen atom induced dissociation device and method based on a photoionization source. The device comprises a sample injection capillary, an ionization source cavity, a repulsion electrode, a vacuum ultraviolet deuterium lamp, a transmission electrode group and a differential electrode, wherein the repulsion electrode, the transmission electrode group and the differential electrode are sequentially arranged in the ionization source cavity at intervals in parallel, the vacuum ultraviolet deuterium lamp penetrates through the ionization source cavity and then stretches into a region between the repulsion electrode and the transmission electrode group, the sample injection capillary sequentially penetrates through the left side wall of the ionization source cavity and a central hole of the repulsion electrode, an outlet end of the sample injection capillary is positioned in the region between the repulsion electrode and the transmission electrode group, and direct-current voltages are applied to the repulsion electrode, the transmission electrode group and the differential electrode. The invention utilizes the characteristic of vacuum ultraviolet light to enable the photoelectric ionization source to generate oxygen atom induced dissociation reaction in situ, thereby reducing the technical threshold and cost and realizing convenient switching between two modes of soft ionization and abundant structural information.

Inventors

LI HAIYANG
FAN ZHIGANG
HUA LEI
JIANG JICHUN
REN MEIHUI
ZHANG ZHENYUAN

Assignees

中国科学院大连化学物理研究所

Dates

Publication Date: 20260505
Application Date: 20260129

Claims (10)

1. The oxygen atom induced dissociation device based on the photoionization source is characterized by comprising a sample injection capillary (1), an ionization source cavity (2), a repulsion electrode (3), a vacuum ultraviolet deuterium lamp (4), a transmission electrode group (5) and a differential electrode (7); The ionization source cavity (2) is of a cylindrical structure which is horizontally arranged, the right side wall of the ionization source cavity is provided with a coaxial circular outlet, the repulsion electrode (3), the transmission electrode group (5) and the differential electrode (7) are sequentially arranged in the ionization source cavity (2) at intervals in parallel along the axis direction from left to right, and the differential electrode (7) is connected to the circular outlet in an insulating manner; the vacuum ultraviolet deuterium lamp (4) penetrates through the upper side wall of the ionization source cavity (2) and then stretches into the area between the repulsion electrode (3) and the transmission electrode group (5), and the photon emergent direction of the vacuum ultraviolet deuterium lamp (4) is perpendicular to the axial direction of the ionization source cavity (2); The sample injection capillary (1) sequentially passes through the left side wall of the ionization source cavity (2) and the central hole of the repulsion electrode (3), the outlet end of the sample injection capillary is positioned in the area between the repulsion electrode (3) and the transmission electrode group (5), and the inlet of the sample injection capillary (1) is positioned in the external environment; The upper side wall of the ionization source cavity (2) is provided with a vacuum extraction opening (6); the repulsive electrode (3), the transmission electrode group (5) and the differential electrode (7) are all applied with direct-current voltages.
2. The photoionization source-based oxygen atom induced dissociation apparatus of claim 1, wherein the vacuum extraction port (6) is located in a region between the transfer electrode set (5) and the differential electrode (7).
3. The photoionization source-based oxygen atom induced dissociation device of claim 1, wherein the set of transfer electrodes (5) comprises at least three transfer electrodes coaxially arranged in an axial direction, and all adjacent electrodes are separated from each other by an insulating ring (8).
4. The photoionization source-based oxygen atom induced dissociation device of claim 3, wherein the insulating ring (8) is made of ceramic or polyetheretherketone, and the insulating ring (8) has an outer diameter of 4-8 mm and a thickness of 4-10 mm.
5. The oxygen atom induced dissociation device based on photoionization source as claimed in claim 3, wherein the transmission electrode, the repulsion electrode (3) and the differential electrode (7) are circular pole pieces with central holes, and the pole pieces are made of conductive metal or flat plates with surfaces plated with conductive metal layers; The thickness of the transmission electrode is 2-4 mm, the diameter of the central hole is 14-28 mm, the thickness of the repulsive electrode (3) is 2-4 mm, the diameter of the central hole is 2-6 mm, the thickness of the differential electrode (7) is 2-6 mm, and the diameter of the central hole is 1-2 mm.
6. An oxygen atom induced dissociation device as claimed in claim 3 characterised in that the repulsive electrodes (3) are applied with a dc voltage of 20-40V, the differential electrodes (7) are applied with a dc voltage of 5-10V, the dc voltages applied to the electrodes in the set of transfer electrodes (5) decrease in sequence from side to side along the axis of the ionization source chamber (2) and the voltage of the first transfer electrode is lower than the dc voltage of the repulsive electrodes (3) and the voltage of the last transfer electrode is higher than the dc voltage of the differential electrodes (7).
7. The oxygen atom induced dissociation device based on photoionization source according to claim 1, wherein the sample-feeding capillary (1) is made of stainless steel, quartz or polyetheretherketone, and the inner diameter of the sample-feeding capillary (1) is 50-500 μm and the length thereof is 10-60 cm.
8. The photoionization source-based oxygen atom induced dissociation apparatus of claim 1, wherein the differential electrode (7) is external to a mass analyzer.
9. An oxygen atom induced dissociation method based on the device of any one of claims 1 to 8, comprising the steps of: Introducing a mixed gas of a sample to be detected and air into the ionization source cavity (2) through the sample injection capillary (1); Starting the vacuum ultraviolet deuterium lamp (4), enabling vacuum ultraviolet light emitted by the vacuum ultraviolet deuterium lamp to act on sample molecules and oxygen molecules simultaneously in an ionization region, enabling the sample molecules to be photoionization to generate sample ions, and enabling the oxygen molecules to be photolyzed to generate ground state oxygen atoms; leading the sample ions from the ionization region to a reaction region formed by the transmission electrode group (5) through an electric field, enabling the sample ions to have ion-atom reaction with the ground state oxygen atoms entering the reaction region under the action of air flow, and inducing the sample ions to dissociate to generate fragment ions; sample ions and fragment ions generated by the reaction are led out through the differential electrode (7) and are conveyed to a mass analyzer for detection.
10. The method for inducing dissociation of oxygen atoms according to claim 9, wherein the air pressure in the ionization source cavity (2) is controlled within the range of 100-1000 Pa by the air pumping system externally connected with the vacuum pumping port (6), and the degree of the dissociation of oxygen atoms can be finely controlled by adjusting the air pressure, so that the ionization source can be conveniently switched between two modes of obtaining molecular ion information or obtaining structural information.

Description

Oxygen atom induced dissociation device and method based on photoionization source Technical Field The invention relates to the technical field of mass spectrometry analysis instruments, in particular to an oxygen atom induced dissociation device and method based on a photoionization source. Background The photoionization technology is used as an important soft ionization method, and has the remarkable advantages of high ionization efficiency, limited fragmentation degree, wide applicability and the like, so that the photoionization technology is widely applied to a plurality of fields such as environmental monitoring, food safety, petrochemical industry, life science and the like. However, the "soft ionization" nature of the photoionization technique also results in extremely limited information on the molecular structure that it provides. When analyzing unknowns or distinguishing isomers with the same molecular weight but different structures, accurate qualitative analysis is often difficult to achieve only by molecular ion peaks, which greatly limits the application of photoionization mass spectrometry in structural analysis. A possible solution to this problem is to fragment the molecular ions into fragment ions with unique characteristics by means of Collision Induced Dissociation (CID). Such as tandem mass spectrometry or in-source collision induced dissociation techniques. However, CID technology, although mature and widely used, is better at distinguishing isomers with different functional groups or obvious difference in functional group positions, while for isomers with highly similar structures such as carbon skeleton isomerism and double bond position isomerism, the resulting fragment patterns tend to have insignificant differences and limited discrimination capability. In recent years, novel induced dissociation methods based on free radical reactions with ions have been demonstrated to provide fragmentation information complementary to CID. However, these methods are currently often limited to implementation in a collision cell of tandem mass spectrometry. The lower gas pressure of (2) results in short reaction time and low collision probability of free radicals and sample ions, and low dissociation efficiency. In addition, the collision cell structure also increases the cost and complexity of the instrument. Disclosure of Invention In view of the above problems, it is an object of the present invention to provide an oxygen atom induced dissociation device and method based on a photoionization source. In order to achieve the above object, the present invention adopts the following technical scheme: The invention provides an oxygen atom induced dissociation device based on a photoionization source, which comprises a sample injection capillary, an ionization source cavity, a repulsion electrode, a vacuum ultraviolet deuterium lamp, a transmission electrode group and a differential electrode, wherein the sample injection capillary is arranged in the ionization source cavity; The ionization source cavity is of a cylindrical structure which is horizontally arranged, the right side wall of the ionization source cavity is provided with a coaxial circular outlet, the repulsion electrode, the transmission electrode group and the differential electrode are sequentially arranged in the ionization source cavity at intervals in parallel from left to right along the axis direction, and the differential electrode is connected to the circular outlet in an insulating manner; the vacuum ultraviolet deuterium lamp penetrates through the upper side wall of the ionization source cavity and then stretches into the area between the repulsion electrode and the transmission electrode group; The sample injection capillary sequentially passes through the left side wall of the ionization source cavity and the central hole of the repulsion electrode, the outlet end of the sample injection capillary is positioned in the area between the repulsion electrode and the transmission electrode group, and the inlet of the sample injection capillary is positioned in the external environment; the upper side wall of the ionization source cavity is provided with a vacuum extraction opening; And direct-current voltages are applied to the repulsive electrode, the transmission electrode group and the differential electrode. The vacuum pumping port is positioned in the area between the transmission electrode group and the differential electrode. The transmission electrode group comprises at least three transmission electrodes coaxially arranged along the axial direction, and all adjacent electrodes are separated and insulated through an insulating ring. The insulating ring is made of ceramic or polyether-ether-ketone, the outer diameter of the insulating ring is 4-8 mm, and the thickness of the insulating ring is 4-10 mm. The transmission electrode, the repulsion electrode and the differential electrode are round pole pieces with central h