WO2023083082A1

WO2023083082A1 - Photoionization ion source having compact structure, and photoionization time-of-flight mass spectrometer

Info

Publication number: WO2023083082A1
Application number: PCT/CN2022/129337
Authority: WO
Inventors: 杨燕婷
Original assignee: 成都艾立本科技有限公司
Priority date: 2021-11-12
Filing date: 2022-11-02
Publication date: 2023-05-19
Also published as: CN114093748A

Abstract

The present invention belongs to the technical field of analytical instruments, and specifically relates to a photoionization ion source having a compact structure, and a photoionization time-of-flight mass spectrometer. The photoionization ion source of the present invention comprises an ultraviolet lamp and an electrode group which are sequentially arranged, an insulating sealing ring being disposed between adjacent electrodes in the electrode group, through hole structures are arranged in the middle of electrodes in the electrode group, and the insulating sealing ring and the electrodes in the electrode group jointly form a columnar cavity; the electrodes in the electrode group comprise a drift head electrode, at least one drift electrode, and a drift tail electrode, which are arranged in sequence, a capillary tube for sample injection being disposed at a side surface of the drift head electrode, and the ultraviolet lamp being disposed at one end of a columnar cavity near the drift head electrode. The photoionization ion source is used in a time-of-flight mass spectrometer, and can effectively simplify the structure of the instrument, reduce the size of the instrument, reduce energy consumption of the instrument, and facilitate popularization and use of the time-of-flight mass spectrometer, having good application prospects.

Description

A compact photoionization ion source and photoionization time-of-flight mass spectrometer

technical field

The invention belongs to the technical field of analytical instruments, and in particular relates to a compact photoionization ion source and a photoionization time-of-flight mass spectrometer.

Background technique

Time of Flight Mass Spectrometer (TOF) is a commonly used mass spectrometer. The mass analyzer of this mass spectrometer is an ion drift tube. The sample is processed into an ion beam by the ion source, and the ion beam enters the field-free drift tube after acceleration, and flies to the ion receiver at a constant speed. The larger the ion mass, the longer the time it takes to reach the receiver, the smaller the ion mass, the shorter the time it takes to reach the receiver, according to this principle, the ions of different masses can be separated according to the m/z value, and then the samples are analyzed. of ions.

In TOF, the ion source is a very important component. The ionization effect of the ion source on the sample is related to the sensitivity of the detection results and other properties. The Chinese invention patent "CN200610011793.2 Vacuum UV lamp ionization device in time-of-flight mass spectrometer" provides a photoionization ion source, which is an ion source device that uses ultraviolet lamps to irradiate sample ions to ionize them. In order to avoid the influence of air on sample ionization, the photoionization ion source in the prior art is equipped with an independent mechanical pump or molecular pump to maintain the vacuum degree of the chamber where the ionization region of the ion source is located to meet the requirements of sample ionization. In addition to the ionization region of the ion source, there are usually other regions in the TOF that need to maintain vacuum, such as the ion transmission region. Therefore, the existing photoionization time-of-flight mass spectrometers usually have multiple mechanical pumps or molecular vacuum pumps for vacuuming. Pump, which makes the structure of the instrument complex, bulky, and high energy consumption during use, which is not conducive to its popularization and application.

Contents of the invention

Aiming at the defects of the prior art, the present invention provides a photoionization ion source and a photoionization time-of-flight mass spectrometer with a compact structure. After the time-of-flight mass spectrometer, the structure of the time-of-flight mass spectrometer can be further simplified, the volume of the instrument can be reduced, and it is convenient to use.

A photoionization ion source with a compact structure, including ultraviolet lamps and electrode groups arranged in sequence, insulating sealing rings are arranged between adjacent electrodes in the electrode group, and through holes are arranged in the middle of the electrodes in the electrode group. A hole structure, the insulating sealing ring and the electrodes in the electrode group together form a columnar cavity;

The electrodes in the electrode group include a drift head electrode, at least one drift electrode and a drift tail electrode arranged in sequence, the side of the drift head electrode is provided with a capillary for sample injection, and the ultraviolet lamp is arranged in a columnar cavity close to Drift one end of the first electrode.

Preferably, a flow controller and a pressure controller are also included, and the flow controller and the pressure controller are connected to the capillary through a bypass.

Preferably, the diameter of the through-hole structure of the first drift electrode and the drift electrode is 1mm-15mm, the size of the central hole of the insulating sealing ring is 1-20mm, and the diameter of the through-hole structure of the drift tail electrode is 0.3-3mm, the length of the columnar cavity is 30-300mm.

Preferably, the drift first electrode is in contact with the base electrode of the ultraviolet lamp.

Preferably, the through-hole structure of the drift tail electrode is a tapered hole.

Preferably, the electrodes in the electrode group further include a sample converging drift electrode, the converging drift electrode is located between the drift first electrode and the drift electrode, and the aperture structure of the sample converging drift electrode is 1mm-3mm , the through-hole structure of the sample converging drift electrode is arranged coaxially with the beam of the ultraviolet lamp.

Preferably, the electrodes in the electrode group further include a vacuum measurement drift electrode, and a vacuum gauge for detecting the vacuum degree of the columnar cavity is arranged on the side of the vacuum measurement drift electrode.

Preferably, a voltage dividing resistor is arranged between the electrodes in the electrode group.

The present invention also provides a photoionization time-of-flight mass spectrometer. The ion source of the photoionization time-of-flight mass spectrometer adopts the above-mentioned photoionization ion source.

Preferably, the rear end of the photoionization ion source is provided with a vacuum chamber in the ion transmission area, the vacuum chamber in the ion transmission area is connected with a device for vacuuming, an ion transporter is arranged in the vacuum chamber of the ion transmission area, and the vacuum chamber in the ion transmission area is provided with an ion transporter. The rear end of the vacuum chamber in the ion transmission area is provided with a small hole electrode for extracting the ion beam, and the small hole electrode is provided with a small hole with a diameter of 0.5-2mm.

The technical solution of the present invention has the following beneficial effects:

1. Through the combination of ultraviolet lamps, electrodes and insulating sealing rings, the sealed cavity for ionization is jointly enclosed. The structure is compact and there are no redundant parts, which can effectively maintain the volume of the sealed cavity of the photoionization ion source within a reasonable range. Inside, so that it can share the vacuuming equipment with the vacuum chamber of the ion transmission area at the back end. Thus, the photoionization ion source of the present invention successfully omits an independent vacuuming device.

2. The preferred solution of the present invention controls the sampling pressure and flow rate of the capillary through the flow controller and the pressure controller, which further reduces the difficulty of maintaining vacuum in the ionization area, makes it easier to omit the independent vacuuming equipment, and at the same time makes the inside of the power supply The air pressure is adjustable, which also avoids the possibility of contamination of the sample on the pressure and flow adjustment device and interference with the detection.

3. The preferred solution of the present invention further reduces the difficulty of maintaining vacuum in the ionization area by rationally setting the size of each component and controlling the diameter and length of the ionization area and the size of the outlet, making it easier to omit the independent vacuuming equipment.

4. In the preferred solution of the present invention, the drift first electrode is in contact with the lamp head electrode of the ultraviolet lamp so that the two are at the same potential, which is beneficial to ensure that the generated ions are not disturbed by the voltage of the ultraviolet lamp, improve ion transmission efficiency, and reduce the setting of the power supply. cost.

5. In the preferred solution of the present invention, the sample convergence drift electrode can make all the measured gases sent into the ionization chamber converge and pass through the effective ionization radius of the ultraviolet lamp. This design can increase the ionization efficiency by 3-10 times.

Apparently, according to the above content of the present invention, according to common technical knowledge and conventional means in this field, without departing from the above basic technical idea of the present invention, other various forms of modification, replacement or change can also be made.

The above-mentioned content of the present invention will be further described in detail below through specific implementation in the form of examples. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention.

Description of drawings

Fig. 1 is the structural representation of the compact photoionization ion source and the vacuum cavity in the ion transmission area connected to the rear end thereof in Example 1;

Fig. 2 is the high sensitivity, full spectrum, on-line detection of the photoionization time-of-flight mass spectrometer of embodiment 2 to benzene standard sample;

Fig. 3 is the result of detecting benzene with a concentration of 16.8 ppbv by the photoionization time-of-flight mass spectrometer in Example 2.

Among them, 1-capillary, 2-UV lamp, 3-drift head electrode, 4-insulation sealing ring, 5-sample convergence drift electrode, 6-vacuum measurement drift electrode, 7-drift electrode, 8-drift tail electrode, 9- Ion transporter, 10-vacuum cavity in ion transport area, 11-small hole electrode, 12-molecular pump, 13-vacuum gauge, 14-flow controller, 15-pressure controller, 16-DC power supply, 17-voltage divider resistor , 18-RF power supply.

Detailed ways

Embodiment 1 A kind of compact photoionization ion source

The present embodiment provides a kind of compact photoionization ion source, as shown in Figure 1, it comprises ultraviolet lamp 2 and electrode group, is provided with insulating sealing ring 4 between the adjacent electrodes in described electrode group, in the electrode group The electrode is made of stainless steel or other metals, and the insulating sealing ring is made of tetrafluoroethylene or other non-metallic materials. The middle parts of the electrodes in the electrode group are all provided with a through-hole structure, and the insulating sealing ring 4 and the electrodes in the electrode group together form a columnar cavity, which is the ionization region of the sample. The ultraviolet lamp 2 is arranged at one end of the cylindrical cavity close to the drifting first electrode 3 . The contact parts of the components constituting the columnar cavity are airtight to maintain the vacuum. The lamp head electrode of the ultraviolet lamp 2 is installed in contact with the drift first electrode 3, so that the two are at the same potential, which is beneficial to ensure that the generated ions will not be disturbed by the voltage of the ultraviolet lamp 2, improve ion transmission efficiency, reduce power supply settings, and reduce costs.

The electrodes in the electrode group include a drift head electrode 3 , a convergence drift electrode 5 , a vacuum measurement drift electrode 6 , a drift electrode 7 and a drift tail electrode 8 arranged in sequence. The number of drift electrodes 7 is three. A voltage dividing resistor 17 is arranged between the electrodes in the electrode group. When the photoionization ion source is working, two or more DC power supplies 16 apply uniform or non-uniform drop voltage from the drifting head electrode to the drifting tail electrode to provide ion migration power for the ionization region. The applied voltage difference ranges from 5-500V.

A capillary 1 for sample injection is provided on the side of the drift first electrode 3, and a sample introduction hole is arranged on the drift first electrode 3, and the sample in the capillary 1 is introduced into the ionization region through the hole. The side of the capillary 1 is provided with a flow controller and a pressure controller. Through the flow controller and the pressure controller, the flow rate of the sample entering the capillary 1 from the outside and the flow rate of the sample entering the ionization region (ie, the injection pressure of the ion source) can be controlled simultaneously, making it easier to maintain the vacuum in the ionization region. In particular, the flow controller of this embodiment is connected to the side of the capillary through a bypass, which can not only adjust the air pressure in the ion source at any time, but also avoid sample contamination caused by connecting a flowmeter in series on the capillary sampling pipeline. question.

The aperture of the through-hole structure of the drift first electrode 3, the vacuum measurement drift electrode 6 and the drift electrode 7 is 10mm, the central hole size of the insulating sealing ring 4 is 10mm, and the thickness of the insulating sealing ring 4 is 1mm. The diameter of the through-hole structure of the drift tail electrode 8 is 1.5 mm, and the length of the columnar cavity is 100 mm.

The hole diameter of the through-hole structure of the sample converging drift electrode 5 is 2 mm, and the through-hole structure of the sample converging drift electrode 5 is arranged coaxially with the beam of the ultraviolet lamp 2 . The setting of the sample converging drift electrode 5 can make all the measured gases sent into the ionization chamber converge and pass through the effective ionization radius of the ultraviolet lamp. This design can increase the ionization efficiency by 3-10 times.

A vacuum gauge 13 for detecting the vacuum degree of the columnar cavity is provided on the side of the vacuum measurement drift electrode 6 .

The through-hole structure of the drift tail electrode 8 is a tapered hole, with the thickness of the hole wall near the through-hole structure. After the sample is ionized in the ionization region, the generated ion beam leaves the ionization region through the through-hole structure of the drift tail electrode 8 and enters the device connected to the rear end of the photoionization ion source.

Embodiment 2 A kind of photoionization time-of-flight mass spectrometer

The present embodiment provides a kind of photoionization time-of-flight mass spectrometer, and its ion source adopts the photoionization ion source of embodiment 1. The photoionization ion source is connected with devices such as an ion lens and a time-of-flight mass analyzer at the rear end through a vacuum chamber 10 in the ion transmission region. In this embodiment, devices whose structures are not specified, such as ion lenses and time-of-flight mass analyzers, belong to the prior art.

An ion transporter 9 is arranged in the vacuum chamber 10 of the ion transport area, and the ion transporter 9 is preferably a quadrupole ion transporter. The rear end of the vacuum chamber 10 in the ion transmission area is provided with a small hole electrode 11 for extracting ion beams, and a small hole with a diameter of 1.5 mm is set on the small hole electrode 11 .

The vacuum chamber 10 in the ion transmission area of the present embodiment is connected with a turbomolecular pump 12 with a pumping speed of 10L/s-300L/s, and the molecular pump 12 can maintain the vacuum of the columnar cavity of the ionization area and the ion transmission area of the ion transmission area at the same time The vacuum degree of chamber 10. In this embodiment, the vacuum degree of the columnar chamber in the ionization region can be maintained at 100-800 Pa, and the vacuum degree of the vacuum chamber in the ion transmission region can be maintained at 0.05-10 Pa, which can meet the testing requirements of various samples.

The results of testing the standard sample of benzene using the photoionization time-of-flight mass spectrometer of this embodiment are shown in FIG. 2 . It can be seen that this embodiment can be used for high-sensitivity, full-spectrum, on-line detection of volatile organic compounds. Detect for the benzene standard sample that contains 16.8ppbv benzene, as shown in Figure 3, the molecular ion peak signal strength that it produces is 171099, noise 31.66, signal-to-noise ratio 5404, detection limit 0.009, shows that the instrument of the present embodiment can reach Very high precision.

It can be seen from the above embodiments that the present invention provides a photoionization ion source that has a compact structure and can share a vacuuming device with the vacuum chamber in the rear-end ion transmission area. The photoionization ion source is applied to a time-of-flight mass spectrometer, The structure of the instrument can be effectively simplified, the volume of the instrument can be reduced and the energy consumption of the instrument can be reduced, which is beneficial to popularization and use of the time-of-flight mass spectrometer, and has good application prospects.

Claims

A kind of compact photoionization ion source, it is characterized in that: comprise the ultraviolet lamp (2) that arranges in sequence and electrode group, be provided with insulating sealing ring (4) between the adjacent electrodes in described electrode group, described electrode The middle parts of the electrodes in the group are all provided with a through-hole structure, and the insulating sealing ring (4) and the electrodes in the electrode group together form a columnar cavity;

The electrodes in the electrode group include a drift first electrode (3), at least one drift electrode (7) and a drift tail electrode (8) arranged in sequence, and a capillary for sampling is provided on the side of the drift first electrode (3) (1), the ultraviolet lamp (2) is arranged at one end close to the drifting first electrode (3) in the columnar cavity.
According to the described photoionization ion source of claim 1, it is characterized in that: also comprise flow controller (14) and pressure controller (15), described flow controller (14) and pressure controller (15) pass through bypass The outlet is connected to the capillary (1).
According to the described photoionization ion source of claim 1, it is characterized in that: the aperture of the through-hole structure of the first drift electrode (3) and the drift electrode (7) is 1mm-15mm, and the insulating sealing ring (4 ) has a center hole size of 1-20mm, the through-hole structure of the drift tail electrode (8) has a diameter of 0.3-3mm, and the length of the columnar cavity is 30-300mm.
The photoionization ion source according to claim 1, characterized in that: the drift head electrode (3) is in contact with the lamp head electrode of the ultraviolet lamp (2).
The photoionization ion source according to claim 1, characterized in that: the through-hole structure of the drift tail electrode (8) is a tapered hole.
According to the photoionization ion source according to claim 1, it is characterized in that: the electrodes in the electrode group also include a sample convergence drift electrode (5), and the convergence drift electrode (5) is located at the first drift electrode (3) and the drift electrode (7), the aperture of the through-hole structure of the sample converging drift electrode (5) is 1mm-3mm, and the through-hole structure of the sample converging drift electrode (5) is connected with the ultraviolet lamp (2) The beam coaxial setting.
According to the described photoionization ion source of claim 1, it is characterized in that: the electrode in the described electrode group also comprises vacuum measurement drift electrode (6), and the side of described vacuum measurement drift electrode (6) is provided with for detecting the A vacuum gauge (13) for the vacuum degree of the column cavity.
The photoionization ion source according to any one of claims 1-7, characterized in that: a voltage dividing resistor (17) is arranged between the electrodes in the electrode group.
A photoionization time-of-flight mass spectrometer, characterized in that: the ion source of the photoionization time-of-flight mass spectrometer adopts the photoionization ion source described in any one of claims 1-8.
According to the photoionization time-of-flight mass spectrometer according to claim 9, it is characterized in that: the rear end of the photoionization ion source is provided with an ion transmission area vacuum chamber (10), and the ion transmission area vacuum chamber (10) is connected with a A device for vacuuming, an ion transporter (9) is arranged in the vacuum chamber (10) of the ion transmission area, and a small hole electrode (11) for extracting ion beams is provided at the rear end of the vacuum chamber (10) of the ion transmission area , the small hole electrode (11) is provided with a small hole with a diameter of 0.5-2mm.