CN111243935A - Ion mobility spectrometer of dielectric barrier discharge ionization source - Google Patents

Abstract

The invention relates to an ion mobility spectrometer, in particular to an ion mobility spectrometer of a dielectric barrier discharge ionization source, which has the advantages of reasonable structure, high detection sensitivity, stability and selectivity by taking dielectric barrier discharge as an ionization source device, and comprises an ionization source, a drift tube and a signal acquisition end, wherein the ionization source comprises a cylindrical shell, a glass tube, a radio frequency electrode, a lead, a radio frequency power supply and an accelerating electrode, the drift tube comprises a metal conducting ring and an insulating ring, the metal conducting ring and the insulating ring are alternately connected, the ionization source comprises a cylindrical shell, a radio frequency power supply, an accelerating electrode, a radio frequency electrode, a quartz glass tube and an accelerating electrode, the accelerating electrode is hermetically arranged at the front end of the cylindrical shell, the quartz glass tube is inserted into the cylindrical shell, the two radio frequency electrodes are inserted into the cylindrical shell and are sleeved on the outer wall of the quartz glass tube, the radio-frequency electrode is also connected with a radio-frequency power supply through a lead.

Description

An ion mobility spectrometer with a dielectric barrier discharge ionization source

technical field

The invention relates to an ion mobility spectrometer, in particular to an ion mobility spectrometer of a dielectric barrier discharge ionization source.

Background technique

Ion Mobility Spectrometry (IMS) is a detection technology developed in the 1970s. Its separation principle is to characterize various chemical substances by the mobility of gaseous ions to analyze and detect various substances. . Ion mobility spectrometer has the advantages of high detection sensitivity, fast measurement response, small instrument size and low cost. It has been widely used in the detection of chemical poisons, drugs, dangerous goods and volatile organic pollutants in the atmospheric environment.

Conventional ion mobility spectrometer mainly includes sampling device, ionization source, drift tube, electronic control part, gas circuit circulation system, signal acquisition and data processing system, etc. Among them, the drift tube is mainly composed of three parts: ion reaction zone, ion gate and drift zone. The ionization source is an important part of ion mobility spectroscopy. The most commonly used ionization sources for existing ion mobility spectrometers mainly include Ni63 ionization sources, corona discharge ionization sources, photoionization (including VUV lamps and lasers) ionization sources, and electrospray ionization sources.

The ionization source based on Ni63 has the advantages of high ionization rate, good stability and high detection sensitivity, but due to the radioactivity of Ni63, the application of ion mobility spectrometer is greatly limited; corona discharge and photoionization ionization sources are suitable for Gas-phase samples are ionized, and the types of ionized samples are limited; electrospray ionization sources are suitable for analyzing liquid samples, but the samples need to undergo complex pretreatment, and the device structure of the ionization source is also complex, so it is not suitable for on-site testing. Therefore, how to design an ion mobility spectrometer with high detection sensitivity and stable detection is a technical problem to be solved.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention overcomes the existing defects, and provides an ion mobility spectrometer with a dielectric barrier discharge ionization source, which has a reasonable structure, uses the dielectric barrier discharge as the ionization source device, and has high detection sensitivity, stability and selectivity. advantage.

In order to solve the above technical problems, the present invention provides the following technical solution: an ion mobility spectrometer of a dielectric barrier discharge ionization source, comprising an ionization source, a drift tube and a signal collection end, the ionization source includes a cylindrical shell, a glass tube, radio frequency electrode, wire, radio frequency power supply and acceleration electrode, the drift tube includes a metal conductive ring and an insulating ring, the metal conductive ring and the insulating ring are alternately connected, the ionization source includes a cylindrical shell, a radio frequency power supply, an acceleration Electrode, radio frequency electrode, quartz glass tube and accelerating electrode, the accelerating electrode is sealed and installed at the front end of the cylindrical shell, the quartz glass tube penetrates into the cylindrical shell, and the radio frequency electrodes are two and protrude into the cylindrical shell The casing is sleeved on the outer wall of the quartz glass tube, the radio frequency electrode is also connected to the radio frequency power supply through a wire, the quartz glass tube contains working gas, and also includes a sampling mechanism, and the sampling mechanism is arranged in the cylindrical casing.

Preferably, the front end of the drift tube is provided with an exhaust port, the rear end of the drift tube is provided with a drift gas inlet, and the rear end of the drift tube is further provided with a signal collection end.

Preferably, the sampling mechanism is a sampling tube.

Preferably, the sampling mechanism is a sample sampling table.

Preferably, the distance between the two RF electrodes is 2-3 cm, and the distance between the lower RF electrode and the bottom end of the quartz glass tube is less than 5 mm.

Preferably, the glass tube is a quartz glass tube or a ceramic tube.

Preferably, the inner diameter of the glass tube is 1-2 mm, and the wall thickness is 0.5-2 mm. .

Beneficial effects of the present invention: The ion mobility spectrometer of the dielectric barrier discharge ionization source of the present invention is used as an ionization source, and the dielectric barrier discharge ionization source has the advantages of small size, low power consumption, stable discharge, etc. Ionization, producing a large number of stable, high-energy ions. Not only can radioactive ionization sources be avoided, but gaseous, liquid or solid samples can be ionized directly. At the same time, the sensitivity, stability and selectivity of the ion mobility spectrometry technique can be further improved, and the application field of ion mobility spectrometry can be broadened.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used to explain the present invention together with the embodiments of the present invention, and do not constitute a limitation to the present invention.

FIG. 1 is a schematic structural diagram of the ion mobility spectrometer of the dielectric barrier discharge ionization source of the present invention.

FIG. 2 is another structural schematic diagram of the ion mobility spectrometer of the dielectric barrier discharge ionization source of the present invention.

Labels in the figure: 1, wire; 2, radio frequency power supply; 3, glass tube; 4, radio frequency electrode; 5, cylindrical shell; 6, exhaust port; 7, insulating ring; 8, conductive ring; 9, ion gate 10. Drift gas inlet; 11. Signal acquisition end; 12. Accelerating electrode; 13. Sampling mechanism; 14. Ion reaction zone; 15. Drift zone; 16. Drift tube.

Detailed ways

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

In the specific implementation, as shown in FIGS. 1 and 2, an ion mobility spectrometer with a dielectric barrier discharge ionization source, the drift tube 16 is a hollow tube composed of several metal conductive rings 8 and insulating rings 7 alternately arranged. , including ion reaction zone 14, ion gate 9, drift zone 15 three parts. The sampling device is installed in the ionization source, the ionization source is closely connected with the front end of the drift tube, and the rear end of the drift tube is connected with the signal acquisition end 11; the carrier gas and the drift gas form a gas circuit circulation inside the drift tube; The signal acquisition part of the instrument is controlled. The drift tube, carrier gas and drift gas gas circuit circulation, electronic control signal acquisition and data processing of the ion mobility spectrometer involved in the present invention belong to the prior art and will not be described in detail.

The characteristics of the present invention are: the ionization source includes a cylindrical shell 5, a radio frequency power supply 2, an accelerating electrode 12, a radio frequency electrode 4 and a glass tube 3, the circular accelerating electrode 12 is sealed and installed at the front end of the cylindrical shell 5, and the sampling mechanism 13 It extends into the cylindrical shell 5 from the side wall; as shown in FIG. 1 , the sampling mechanism 13 is a sampling tube, and as shown in FIG. , the radio frequency electrode 4 and the radio frequency power supply 2 are connected by the wire 1, the glass tube 3 is a quartz glass tube or a ceramic glass tube, its inner diameter is between 1 and 2 mm, and its wall thickness is between 0.5 and 2 mm, and a working gas is introduced into the tube. .

The radio frequency electrode 4 is annular, the distance between the two radio frequency electrodes 4 is 2-3 cm, and the distance between the lower radio frequency electrode 4 and the bottom end of the glass tube 3 is less than 5 mm.

The dielectric barrier discharge ionization source ion mobility spectrometer shown in Figure 1 is used to directly test gas samples. The sampling mechanism 13 adopts a sampling tube and is installed on the side wall of the cavity of the cylindrical casing 5 of the ionization source, and the sampling tube extends into the cylindrical casing from the side wall. When in use, a working gas with a stable flow rate is introduced into the glass tube 3. After the power is turned on, the working gas generates stable plasma inside and near the end of the glass tube 3 through dielectric barrier discharge, and the plasma further reacts under atmospheric pressure conditions. The sample to be tested is introduced into the cylindrical shell 5 of the ionization source through the sampling tube, and the reactant ions react with the sample to be tested by molecular ions to generate the product ions of the sample to be tested. The product ions enter the ion reaction zone under the boost of the accelerating electrode 12. Under the action of the electric field, the product ions enter the drift zone through the periodically opened ion gate 9, and the uniform electric field formed by the annular conductive ring 8 and the insulating ring 7 On the one hand, the product ions obtain energy from the electric field for directional drift, and on the other hand, they continuously collide with the neutral drift gas molecules in the opposite flow and lose energy. They are not the same, so their migration rates are different in the electric field, so that different ions arrive at the signal acquisition part at different times and are separated.

The dielectric barrier discharge ionization source ion mobility spectrometer shown in Figure 2 is used to directly test solid or liquid samples. The sampling mechanism is designed as a sample sampling stage for carrying solid or liquid samples. When in use, the sample to be tested is placed into the ionization source device through the sampling stage, and is ionized by the ionization source to generate product ions. The product ions enter the ion reaction zone through the boosting action of the accelerating electrode. The ion gate enters the drift region, and finally reaches the signal acquisition and data processing part under the uniform electric field formed by the insulating ring and the conductive ring. Due to the different mass, charge, collision cross-section and spatial configuration of these product ions, their respective migration rates in the electric field are different, so that different ions arrive at the signal acquisition part at different times and are separated.

The above are preferred embodiments of the present invention. Those skilled in the art can also make changes and modifications to the above-mentioned embodiments. Therefore, the present invention is not limited to the above-mentioned specific embodiments. Any obvious improvement, substitution or modification made on the basis of the invention belongs to the protection scope of the present invention.

Claims (7)

1. An ion mobility spectrometer of a dielectric barrier discharge ionization source, characterized in that: the ionization source comprises a cylindrical shell (5), a glass tube (3), a radio frequency electrode (4), a lead (1), a radio frequency power supply (2) and an accelerating electrode (12), wherein the ionization source comprises an ionization source, a drift tube (16) and a signal acquisition end (11), the drift tube (16) comprises a metal conducting ring (8) and an insulating ring (7), the metal conducting ring (8) and the insulating ring (7) are alternately connected, the ionization source comprises the cylindrical shell (5), the radio frequency power supply (2), the accelerating electrode (12), the radio frequency electrode (4), a quartz glass tube (3) and the accelerating electrode (12), the accelerating electrode (12) is hermetically arranged at the front end of the cylindrical shell (5), the quartz glass tube (3) is inserted into the cylindrical shell (5), the radio frequency electrodes (4) are two and are inserted into the cylindrical shell (5) and are sleeved on the outer wall of the quartz glass tube (3), the radio frequency electrode (4) is connected with a radio frequency power supply (2) through a wire (1), the quartz glass tube (3) contains working gas and further comprises a sampling mechanism (13), and the sampling mechanism (13) is arranged in the cylindrical shell (5).

2. The ion mobility spectrometer of the dielectric barrier discharge ionization source of claim 1, characterized in that: the front end of drift tube (16) is equipped with gas vent (6), the tail end of drift tube (16) is equipped with drift gas entry (10), the tail end of drift tube (16) still is equipped with signal acquisition end (11).

3. The ion mobility spectrometer of the dielectric barrier discharge ionization source of claim 1, characterized in that: the sampling mechanism (13) is a sampling tube.

4. The ion mobility spectrometer of the dielectric barrier discharge ionization source of claim 1, characterized in that: the sampling mechanism (13) is a sample sampling platform.

5. The ion mobility spectrometer of the dielectric barrier discharge ionization source of claim 1, characterized in that: the distance between the two radio frequency electrodes (4) is 2-3 cm, and the distance between the radio frequency electrode (4) at the lower part and the bottom end of the quartz glass tube (3) is less than 5 mm.

6. The ion mobility spectrometer of the dielectric barrier discharge ionization source of claim 1, characterized in that: the glass tube (3) is a quartz glass tube or a ceramic tube.

7. The ion mobility spectrometer of the dielectric barrier discharge ionization source of claim 1, characterized in that: the inner diameter of the glass tube (3) is 1-2 mm, and the wall thickness is 0.5-2 mm.

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