阅读说明：本技术 一种楔形电极离子迁移谱仪 (Wedge-shaped electrode ion mobility spectrometer ) 是由 黄超群 夏磊 李爱悦 沈成银 储焰南 于 2021-01-04 设计创作，主要内容包括：本发明提出一种楔形电极离子迁移谱仪,包括离子迁移管和信号探测和处理单元,离子迁移管包括离子存储区,离子门,迁移区,其中迁移区金属电极分别有左楔形、右楔形和左右对称楔形三种结构。离子通过离子门进入迁移区后,在楔形电极形成的非均匀电场内迁移,最终被信号探测与处理单元探测和分析,获得检测物的离子迁移谱图。利用这种楔形电极离子迁移谱技术,可获得三种功能各异的离子迁移谱仪,即：检测灵敏度增强、信号分辨率降低；信号分辨率增强、检测灵敏度降低和检测灵敏度不变,信号分辨率增强等三种仪器,以适应不同场合对仪器的不同需求。(The invention provides a wedge-shaped electrode ion mobility spectrometer, which comprises an ion mobility tube and a signal detection and processing unit, wherein the ion mobility tube comprises an ion storage region, an ion gate and a mobility region, and metal electrodes in the mobility region respectively have a left wedge-shaped structure, a right wedge-shaped structure and a left-right symmetrical wedge-shaped structure. After ions enter the migration area through the ion gate, the ions migrate in the non-uniform electric field formed by the wedge-shaped electrode and are finally detected and analyzed by the signal detection and processing unit, and an ion migration spectrogram of a detected object is obtained. By using the wedge-shaped electrode ion mobility spectrometry technology, three ion mobility spectrometers with different functions can be obtained, namely: the detection sensitivity is enhanced, and the signal resolution is reduced; signal resolution enhancement, detection sensitivity reduction, detection sensitivity invariance, signal resolution enhancement and the like so as to adapt to different requirements of different occasions on instruments.)

1. A wedge electrode ion mobility spectrometer, characterized by: the ion mobility tube comprises an ion storage region, an ion gate and a mobility region, wherein a metal electrode of the mobility region is one of a left wedge structure, a right wedge structure or a bilateral symmetry wedge structure; an ion gate is arranged between the ion storage area and the migration area, and a signal detection and processing unit is arranged at the outlet of the tail end of the migration area; ions generated by a molecular-ion reaction or electrospray ionization means are stored in an ion storage area under the action of an ion gate, when the ion gate is opened, ion beam clusters enter a migration area, migrate downstream under the action of a non-uniform electric field E formed by a wedge-shaped electrode, reach a signal detection and processing unit and are detected and analyzed to obtain an ion migration spectrogram of a detected object;

the inner ring of the wedge-shaped electrode is annular, the cross section of the inner ring is wedge-shaped, the wedge-shaped slope surface of the left wedge-shaped electrode faces one side of the inlet of the migration zone, the wedge-shaped slope surface of the right wedge-shaped electrode faces one side of the outlet of the migration zone, and the wedge-shaped slope surfaces of the bilateral symmetry wedge-shaped electrodes are bilateral symmetry with the wedge tip part as the center;

when the migration area adopts a plurality of left wedge-shaped electrodes, the non-uniform electric field generated in the migration area is used for improving the ion passing rate, improving the detection sensitivity and reducing the signal resolution of the instrument;

when the migration area adopts a plurality of right wedge-shaped electrodes, the non-uniform electric field generated in the migration area is used for improving the signal resolution of the instrument and reducing the detection sensitivity of the instrument;

when the migration area adopts a plurality of bilateral symmetry wedge electrodes, the non-uniform electric field generated in the migration area keeps the detection sensitivity of the instrument unchanged, and the signal resolution of the instrument is improved.

2. The wedge electrode ion mobility spectrometer of claim 1, wherein: the ionization source of the ions in the ion storage region comprises a photoionization ionization source, a radioactive ionization source, a corona discharge ionization source, a plasma ionization source or a film type ionization source, and is generated in the reaction region through ion-molecule reaction in an ionization mode or directly generated through an electrospray ionization source.

3. The wedge electrode ion mobility spectrometer of claim 1, wherein: the ion gate is a Bradbury-Nielson type or a Tyndall-Powell type ion gate.

4. The wedge electrode ion mobility spectrometer of claim 1, wherein: the inner ring of the left wedge-shaped electrode is annular, the outer ring of the left wedge-shaped electrode is annular, regular or irregular polygon, the material is metal or the material with a conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

5. The wedge electrode ion mobility spectrometer of claim 1, wherein: the inner ring of the right wedge-shaped electrode is annular, the outer ring of the right wedge-shaped electrode is annular, regular or irregular polygon, the right wedge-shaped electrode is made of metal or a material with a conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

6. The wedge electrode ion mobility spectrometer of claim 1, wherein: the inner ring of the bilateral symmetry wedge-shaped electrode is annular, the outer ring is annular, regular or irregular polygon, the material is metal or the material with conductive coating on the surface, and the height h of the wedge-shaped electrode and the thickness of the electroded is a ratio of

7. The wedge electrode ion mobility spectrometer of claim 1, wherein: the height h of the wedge is the height of the triangle of the wedge tip, and the electrode thickness d is the thickness of the wedge electrode in the axial direction.

Technical Field

The invention belongs to the field of analytical instruments and detection, and particularly relates to a wedge-shaped electrode ion mobility spectrometer.

Background

The ion mobility spectrometry is characterized by utilizing the difference of the migration speeds of ions in an electric field under atmospheric pressure to realize the rapid separation and detection of the ions, has simple structure, high detection sensitivity, high response speed and the like, is widely applied to the on-site rapid qualitative detection of dangerous goods such as explosives, drugs, chemical warfare agents and the like, and has hundreds of thousands of ion mobility spectrometry detection devices which are operated in the global airports, customs and the like at present according to statistics. In addition to the field of public safety, ion mobility spectrometry is also used in other fields, such as purity detection of food, detection of environmental pollutants, quality control in the pharmaceutical industry, and biomarker lookup in patient breaths.

The ion mobility tube is the core of the ion mobility spectrometer, and the traditional structure of the ion mobility tube is formed by mutually isolating and combining a standard metal electrode ring and an insulating ring. The metal electrode rings are connected in series through a divider resistor, and a uniform electric field is formed in an ion migration area of the migration tube. After passing through the ion gate, ions migrate to the downstream of the migration region under the action of the uniform electric field, reach the signal detection and processing unit and are detected and analyzed, and an ion migration spectrogram of a detected object is obtained. The velocity of motion of the ions follows the following equation:

v＝KE

wherein v is the moving speed of the ions, K is the mobility of the object to be detected, and E is the electric field intensity of the migration area.

In recent years, researchers generate a non-uniform electric field in an ion migration tube by changing the control mode of an ion gate in the ion migration tube, so that more ions pass through a migration area and reach a signal detection and processing unit, and the detection sensitivity of an instrument is improved; or the broadening of ions in the migration process is compressed, and the signal resolution of the instrument is improved. So far, there is no published report on improving the performance of an ion mobility spectrometer by changing the structure of an electrode ring and generating a non-uniform electric field in a migration region.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: by changing the structure of the electrode ring in the migration area of the ion migration tube, a non-uniform electric field is generated in the migration area, and the non-uniform electric field can influence the motion track of ions in the migration area, so that the aim of enhancing the detection sensitivity or signal resolution of the ion migration spectrum is fulfilled. The method comprises the following steps: three wedge electrode rings such as left wedge, right wedge and bilateral symmetry wedge are designed to replace the traditional metal electrode ring in the migration area of the ion mobility tube, a non-uniform electric field is formed in the migration area, the ion motion in the migration area is modulated to different degrees, and the improvement and the enhancement of core indexes such as the detection sensitivity and the resolution of the ion mobility spectrometer are realized.

The technical scheme adopted by the invention for solving the technical problems is as follows: a wedge-shaped electrode ion mobility spectrometer comprises an ion mobility tube and a signal detection and processing unit, wherein the ion mobility tube comprises an ion storage region, an ion gate and a mobility region, and a metal electrode in the mobility region is one of a left wedge-shaped structure, a right wedge-shaped structure or a left-right symmetrical wedge-shaped structure; an ion gate is arranged between the ion storage area and the migration area, and a signal detection and processing unit is arranged at the outlet of the tail end of the migration area; ions generated by a molecular-ion reaction or electrospray ionization means are stored in an ion storage area under the action of an ion gate, when the ion gate is opened, ion beam clusters enter a migration area, migrate downstream under the action of a non-uniform electric field E formed by a wedge-shaped electrode, reach a signal detection and processing unit and are detected and analyzed to obtain an ion migration spectrogram of a detected object;

the inner ring of the wedge-shaped electrode is annular, the cross section of the inner ring is wedge-shaped, the wedge-shaped slope surface of the left wedge-shaped electrode faces one side of the inlet of the migration zone, the wedge-shaped slope surface of the right wedge-shaped electrode faces one side of the outlet of the migration zone, and the wedge-shaped slope surfaces of the bilateral symmetry wedge-shaped electrodes are bilateral symmetry with the wedge tip part as the center;

when the migration area adopts a plurality of left wedge-shaped electrodes, the non-uniform electric field generated in the migration area is used for improving the ion passing rate, improving the detection sensitivity and reducing the signal resolution of the instrument;

when the migration area adopts a plurality of right wedge-shaped electrodes, the non-uniform electric field generated in the migration area is used for improving the signal resolution of the instrument and reducing the detection sensitivity of the instrument;

when the migration area adopts a plurality of bilateral symmetry wedge electrodes, the non-uniform electric field generated in the migration area keeps the detection sensitivity of the instrument unchanged, and the signal resolution of the instrument is improved.

Further, the ions in the ion storage region include a photoionization ionization source, a radioactive ionization source, a corona discharge ionization source, a plasma ionization source or a thin film ionization source, and are generated in the reaction region by an ion-molecule reaction in an ionization manner or directly generated by an electrospray ionization source.

Further, the ion gate is a Bradbury-Nielson type or a Tyndall-Powell type ion gate.

Furthermore, the inner ring of the left wedge-shaped electrode is annular, the outer ring of the left wedge-shaped electrode is annular, regular or irregular polygonal, the material is metal or a material with a conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

Furthermore, the inner ring of the right wedge-shaped electrode is annular, the outer ring of the right wedge-shaped electrode is annular, regular or irregular polygon, the right wedge-shaped electrode is made of metal or a material with a conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

Furthermore, the inner ring of the bilateral symmetry wedge-shaped electrode is annular, the outer ring is annular, regular or irregular polygonal, the material is metal or the material with a conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

Further, the height h of the wedge is the height of the triangle at the tip of the wedge, and the thickness d of the electrode is the thickness of the wedge electrode in the axial direction.

Compared with the prior art, the invention has the advantages that:

(1) the invention uses three wedge-shaped electrode rings to replace a metal electrode in the traditional migration tube, and generates a non-uniform electric field in the migration region of the migration tube to modulate the motion track of ions in the migration region, thereby realizing the improvement and the promotion of the performance of the ion mobility spectrometer.

(2) According to the invention, when the ion mobility tube migration area adopts the left wedge-shaped electrode, the ion mobility spectrometer with enhanced detection sensitivity and reduced resolution can be obtained; when the right wedge-shaped electrode is adopted, the ion mobility spectrometer with enhanced signal resolution and reduced detection sensitivity can be obtained; when the bilateral symmetry wedge-shaped electrodes are adopted, the ion mobility spectrometer with unchanged instrument detection sensitivity and enhanced signal resolution can be obtained. The three instruments with different functions can meet different requirements of different occasions on the instruments.

Drawings

FIG. 1(a) schematic diagram of a left wedge electrode ion mobility spectrometer;

FIG. 1(b) schematic diagram of a right wedge electrode ion mobility spectrometer;

FIG. 1(c) is a schematic diagram of a bilaterally symmetric wedge-shaped electrode ion mobility spectrometer;

FIG. 2 is a graph of a simulation of the electric field in the transition region and ion trajectories of a conventional ring electrode;

FIG. 3 is a simulation diagram of the electric field and ion trajectory of the migration region formed by the left wedge-shaped electrode;

FIG. 4 is a simulation diagram of the electric field and ion trajectory of the migration region formed by the right wedge-shaped electrode;

FIG. 5 is a simulation diagram of the electric field and ion trajectory of the migration region formed by the left and right wedge-shaped electrodes.

The reference numbers in the figures mean: 1 is an ion migration tube, 2 is a signal detection and processing unit, 3 is an ion storage area, 4 is an ion gate, 5 is a migration area, 6 is a left wedge-shaped electrode, 7 is a right wedge-shaped electrode, 8 is a bilateral symmetry wedge-shaped electrode, and 9 is a standard circular ring electrode

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention without creative efforts.

As shown in fig. 1(a), fig. 1(b), and fig. 1(c), the present invention is an ion mobility spectrometer having a wedge-shaped mobility region, and is different from a conventional ion mobility spectrometer in that: the electrode of the migration area of the ion migration tube can be a wedge-shaped electrode and can be one of a left wedge-shaped structure, a right wedge-shaped structure and a bilaterally symmetrical wedge-shaped structure.

According to the embodiment of the present invention, as shown in fig. 1, the wedge-shaped electrode specifically refers to: the outer ring of the electrode can be annular, regular or irregular polygonal, the inner ring is annular, and the section of the inner ring is wedge-shaped;

the height h of the wedge is defined as the height of a triangle at the tip of the wedge, and the thickness d of the electrode is defined as the thickness of the wedge electrode in the axial direction;

as shown in fig. 1(a), the wedge-shaped slope of the left wedge-shaped electrode 6 faces the inlet side of the migration zone; the inner ring is annular, the outer ring can be annular, regular or irregular polygon, the material is metal or material with conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

As shown in fig. 1(b), the wedge-shaped slope of the right wedge-shaped electrode 7 faces the outlet side of the migration zone, the inner ring of the right wedge-shaped electrode is annular, the outer ring can be annular, regular or irregular polygonal, the material is metal or a material with a conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

As shown in FIG. 1(c), the wedge-shaped slope surface of the bilateral symmetric wedge-shaped electrode 8 is bilateral symmetric with the wedge-shaped tip part as the center, the inner ring is annular, the outer ring can be annular, regular or irregular polygon, the material is metal or the material with conductive coating on the surface, and the ratio of the height h of the wedge to the thickness d of the electrode is

The three wedge-shaped electrodes generate non-uniform electric fields with different electric field distributions in the migration region to modulate the motion trail of ions in the migration region, so that the detection sensitivity and the resolution of the ion mobility spectrometer are improved.

Fig. 1(a) is a schematic diagram of a left wedge-shaped electrode ion mobility spectrometer, which comprises an ion mobility tube 1 and a signal detection and processing unit 2, wherein the ion mobility tube 1 comprises an ion storage region 3, an ion gate 4, a mobility region 5 and a plurality of left wedge-shaped electrodes 6. An ion gate 4 is arranged between the ion storage area 3 and the migration area 5, and a signal detection and processing unit 2 is arranged at the outlet position at the tail end of the migration area; ions generated by means of molecular-ion reaction or electrospray ionization and the like are stored in the ion storage region 3 under the action of the ion gate 4, when the ion gate 4 is opened, ion beam groups enter the migration region 5, migrate to the downstream of the migration region 5 under the action of the electric field E, and reach the signal detection and processing unit 2 under the action of the electric field of the migration electric field E, so that an ion migration spectrogram of a detected object is obtained.

The detection sensitivity S of the ion mobility spectrometer is measured by the ion number N finally reaching the signal detection and processing unit 2, and the more the ion number reaching the signal detection and processing unit 2 is, the higher the detection sensitivity of the instrument is; i.e. the detection sensitivity S is proportional to the number of ions arriving at the signal detection and processing unit 2: k ═ S₁N，K₁Is a scaling factor.

The time difference Δ T of different ions arriving at the signal detection and processing unit 2 represents the signal broadening generated after ions on the same horizontal plane pass through the migration zone, and the larger Δ T, the wider the signal broadening and the worse the signal resolution R of the instrument. The signal resolution R is therefore inversely proportional to the time difference Δ T:K₂f (Δ T) is a function positively correlated to Δ T as a scaling factor.

The invention carries out theoretical calculation and simulation on the ion passing rate and the motion trail of the uniform electric field formed by the ions in the traditional circular ring electrode and the non-uniform electric field formed by the wedge-shaped electrode and the migration time of the ions reaching the signal detection and processing unit 2. The simulation conditions were: the inner diameter of the migration area is 18mm, when the ion gate 4 is closed, 81 single-charge ions are placed in front of the ion gate 4, the ions are uniformly distributed on a straight line perpendicular to the axis of the migration area 5 from the central axis of the migration area to two sides, the interval between the two ions is 0.2mm, the electric field intensity of the migration area is 330V/cm, and the effective signal detection radius of the signal detection and processing unit 2 is 5 mm. Considering that the motion trajectories of the ions in the migration region are symmetrically distributed with the central axis of the migration region as a symmetry axis, fig. 2 to 5 only show the motion trajectories of the ions at one side of the migration region and simulation results.

As shown in fig. 2, the conventional ion mobility spectrometer mobility region uses a standard circular ring electrode 9 that generates a uniform electric field in the mobility region 3. When the ion gate 4 is opened, ions enter the migration region 3 under the action of the electric field and migrate toward the signal detection and processing unit 2. Due to the free diffusion of ions during the migration process and the distortion of the electric field at the edge of the migration tube, the number N of ions finally arriving at the signal detection and processing unit 2 is 56, and the time difference Δ T of arriving at the signal detection and processing unit 2 is 2.36 ms.

FIG. 3 shows the simulation result of the migration region electrode being the left wedge electrode, when the aspect ratio of the left wedge electrodeThe left wedge electrode generates a non-uniform electric field in the migration region. When the ion gate 4 is opened, the number N of ions finally arriving at the signal detection and processing unit 2 is 60, and the time difference Δ T of the ions arriving at the signal detection and processing unit 2 is 3.41 msec. The number of ions passed increased by 7% compared to the results of a conventional ion mobility spectrometer, but the signal broadening increased by 44.5%. This shows that the left wedge electrode ion mobility spectrometer is beneficial to improving the detection sensitivity of the instrument and reducing the signal resolution. And as the aspect ratio of the wedge-shaped electrode is larger, the detection sensitivity is also increased, but the signal resolution is also deteriorated. In order to maintain the balance between detection sensitivity and signal resolution, and combine the ease of fabrication of the instrument, the aspect ratio of the left wedge electrodeIs suitable.

FIG. 4 shows the simulation result of the right wedge electrode as the migration region electrode, and the aspect ratio of the right wedge electrodeThe right wedge-shaped electrode also generates a non-uniform electric field in the migration zone. When the ion gate 4 is opened, the number N of ions finally arriving at the signal detection and processing unit 2 is 50, and the time difference Δ T of the ions arriving at the signal detection and processing unit 2 is 0.79 msec. The number of ions passed was reduced by 10.7% compared to the results of a conventional ion mobility spectrometer, but the signal broadening was reduced by 67.4%. This indicates that the right wedge electrode ion mobility spectrometer is beneficial to improving the signal resolution and reducing the detection sensitivity. Also, as the aspect ratio of the wedge electrode is larger, the signal resolution increases, but the detection sensitivity also deteriorates. In order to maintain the balance between the detection sensitivity and the resolution, and combine the difficulty of manufacturing the instrument, the aspect ratio of the right wedge-shaped electrodeIt is more suitable.

FIG. 5 shows the simulation result of the laterally symmetric wedge-shaped electrode as the electrode in the migration region, and the aspect ratio of the wedge-shaped electrodeThe bilateral symmetry wedge-shaped electrode also generates a non-uniform electric field in the migration region, when the ion gate 4 is opened, the number N of ions finally reaching the signal detection and processing unit 2 is 56, and the time difference Delta T of the ions reaching the signal detection and processing unit 2 is 1.52 milliseconds. Compared with the results of the conventional ion mobility spectrometer, the number of ions passing through is unchanged, and the signal broadening is reduced by 35.6%. The result shows that the bilateral symmetry wedge-shaped electrode ion mobility spectrometer is beneficial to improving the signal resolution ratio while keeping the detection sensitivity unchanged. And, the aspect ratio of the bilaterally symmetrical wedge-shaped electrodesThe signal resolution of the instrument is highest.

The above examples are for the purpose of describing the invention only and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. Various equivalent substitutions and modifications can be made without departing from the spirit and principles of the invention, and are intended to be within the scope of the invention.

The present description is not set forth in detail in order to not unnecessarily obscure the present invention.