CN114334601B - Mass spectrometry ion extraction device and method - Google Patents
Mass spectrometry ion extraction device and method Download PDFInfo
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Abstract
本发明公开了质谱分析离子提取装置及方法，包括依次设置的用于产生待测物离子的离子源、气帘腔、采样腔及离子光学组件；气帘腔的入口端由带气帘孔的锥形气帘板组成，其侧壁设置有支路提供气帘气，气帘腔内设置有强聚焦电极组件，强聚焦电极组件靠近气帘孔的一端与气帘板内壁之间形成狭缝；采样腔包括采样锥、高气压离子传输组件，采样腔的出口端设置有第二差分孔。本发明通过对提取接口进行改进，增大气帘孔和采样锥的距离，通过施加空间强聚焦静电四极电场对经过气帘孔提取的离子进行聚焦，提高离子群的密度，从而提高采样锥的提取效率，降低溶剂离子加合物的浓度。
The present invention discloses a mass spectrometry ion extraction device and method, comprising an ion source, an air curtain chamber, a sampling chamber and an ion optical component arranged in sequence for generating ions of an object to be detected; the inlet end of the air curtain chamber is composed of a conical air curtain plate with an air curtain hole, and a branch is arranged on its side wall to provide air curtain gas, and a strong focusing electrode assembly is arranged in the air curtain chamber, and a slit is formed between one end of the strong focusing electrode assembly close to the air curtain hole and the inner wall of the air curtain plate; the sampling chamber includes a sampling cone and a high-pressure ion transmission component, and a second differential hole is arranged at the outlet end of the sampling chamber. The present invention improves the extraction interface, increases the distance between the air curtain hole and the sampling cone, focuses the ions extracted through the air curtain hole by applying a spatial strong focusing electrostatic quadrupole electric field, and increases the density of the ion group, thereby improving the extraction efficiency of the sampling cone and reducing the concentration of solvent ion adducts.
Description
Technical Field
The invention belongs to the technical field of mass spectrometry, and particularly relates to a mass spectrometry ion extraction device and a mass spectrometry ion extraction method.
Background
The sample or analyte in the mass spectrometer for analysis is typically ionized in an atmospheric environment, and then ions are introduced into the vacuum chamber of the mass spectrometer. Such atmospheric pressure ion sources have a central advantage in sample ionization, but introducing ions from an atmospheric pressure ion source into a vacuum chamber generally requires an excellent performance interface between the ion source and the vacuum chamber for efficient extraction of ions. Taking liquid phase tandem mass spectrometry (LC-MS/MS) as an example, common atmospheric pressure ion sources include Electrospray (ESI), atmospheric pressure chemical ionization source (APCI), and the like, and after ionization, the sample generates ions and other neutral substances. In particular to an ESI ion source, charged liquid drops are generated through a high-voltage spray needle, solvent is gradually removed through heating the liquid drops, ions are formed, and sample ions are extracted through a vacuum interface. According to the research results of the literature, the ion loss mostly occurs in the vacuum interface in the ion transmission process from atmospheric pressure to vacuum, and the actual extraction efficiency is not more than 1%, so that the design of the vacuum interface is critical to the sensitivity of the instrument.
As described above, the ESI and APCI sources operate at atmospheric pressure, i.e., the ionization produces many neutral molecules or other uncharged particles in addition to the analyte ions, and due to the extraction of vacuum negative pressure, this material also enters the vacuum interface with the ions and eventually may reach the mass spectrum detector, resulting in reduced mass spectrum sensitivity. Taking the most common ESI source as an example, the ionization thereof produces substances that have more solvent molecules, or solvent ion adducts, in addition to ions, with more loss of ions at the vacuum interface.
The design of the current commercial LC-MS/MS vacuum interface mainly comprises two types, namely a sampling cone and a capillary tube. For example, the ESI ion source described in patent EP2260503B1, the vacuum interface is a charged capillary tube, and the solvent is reduced to the greatest extent by the air curtain gas into the vacuum of the instrument, where the charged capillary tube can provide a transmission channel for ions while achieving vacuum differentiation. In patent US6759650, a vacuum interface scheme for sampling cones is provided, and ions pass through an air curtain plate, a sampling cone and an extraction cone in sequence from an atmospheric pressure environment and then enter an ion transmission system. Compared with the capillary tube design, the sampling cone design has the advantages that the sampling cone is not easy to block, the sampling cone is convenient to replace, the processing cost of the sampling cone is low, the heat conduction of the sampling cone is better, and the phenomenon of sample condensation in a free injection expansion area can be avoided to a certain extent. Most of the current schemes based on sampling cones adopt a direct extraction mode, namely, the direct extraction mode is conducted through the ESI spray needle and the sampling cone or the voltage on the air curtain plate, and the ion sampling mode is conducted in an additional negative pressure suction mode, so that the efficiency of the mode is low. Therefore, patent DE 102004045706A1 proposes a new design, in which an auxiliary electrode is added to the ion source to improve the ion extraction efficiency of the interface, but the auxiliary electrode reduces the desolvation process time of the ions, and many ions are annihilated on the curtain plate. In addition, there are designs that deliver ion extraction efficiency by increasing the aperture of the sampling cone, which is viable, but require increased vacuum pump loading, with a concomitant increase in cost in commercial exploitation.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention aims to provide a mass spectrometry ion extraction device and a mass spectrometry ion extraction method, which are used for providing an ion channel, assisting in heating and space strong focusing an electrostatic quadrupole electric field on the basis of the existing air curtain-sampling cone vacuum interface design, and realizing the function similar to radio frequency cooling focusing in a smart and simple way, thereby realizing the efficient extraction of ions and improving the sensitivity of mass spectrometry. The method is realized by the following technical scheme:
the mass spectrometry ion extraction device comprises an ion source, an air curtain cavity, a sampling cavity and an ion optical component which are sequentially arranged;
The ion source is used for generating ions of an object to be detected and comprises an electrospray source ESI, an atmospheric pressure chemical ionization source APCI and other atmospheric pressure sources;
The inlet end of the air curtain cavity consists of a conical air curtain plate, an air curtain hole is formed in the middle of the air curtain plate, a branch is arranged on the side wall of the air curtain cavity to provide air curtain gas, a strong focusing electrode assembly is arranged in the air curtain cavity, and a slit for the air curtain gas to pass through is formed between one end of the strong focusing electrode assembly, which is close to the air curtain hole, and the inner wall of the air curtain plate, so that the air curtain gas can be blown out of the air curtain hole reversely through the slit;
The sampling cavity comprises a sampling cone and a high-pressure ion transmission component, a second differential hole is formed in the outlet end of the sampling cavity, the ion optical component is arranged corresponding to the second differential hole, an interface is arranged on the side edge of the sampling cavity and is externally connected with a backing pump, and the ion optical component comprises a transmission system such as a quadrupole rod, a hexapole rod, an octapole rod and an ion funnel.
Further, the strong focusing electrode assembly comprises a heating sleeve, an outer cylinder electrode and an inner porous extraction electrode, wherein the heating sleeve, the outer cylinder electrode and the inner porous extraction electrode are coaxially arranged, the inner porous extraction electrode is arranged inside the outer cylinder electrode and is provided with a conical inlet end, the conical inlet end extends out of the outer cylinder electrode, the heating sleeve is arranged on the outer surface of the outer cylinder electrode and extends to the outer surface of the conical inlet end of the inner porous extraction electrode, and the taper of the conical inlet end is matched with that of the air curtain plate. The heating sleeve is used for heating the conical inlet ends of the outer cylinder electrode and the inner porous extraction electrode and preventing neutral substances from depositing.
Further, the surface of the inner porous extraction electrode is distributed with a first group of through holes and a second group of through holes, a plurality of groups of through holes are sequentially arranged at intervals in the first group of through holes and the second group of through holes, and the first group of through holes and the second group of through holes are rectangular holes or square holes.
Further, the first group of through holes and the second group of through holes are respectively provided with four rectangular holes or square holes, and are uniformly distributed around the circumference of the inner porous extraction electrode, the adjacent rectangular holes or square holes in the first group of through holes are arranged at 90 degrees, and the radial positions of the rectangular holes or square holes in the second group of through holes are distributed in a 45-degree rotating manner.
Further, the space between adjacent holes in each group of through holes is larger than the size of a single hole, the hole pitch sizes of different groups are the same or different, and the hole pitch sizes of the same groups are the same.
Further, the outer cylindrical electrode and the inner porous extraction electrode are respectively applied with a direct current voltage, and the voltage of the inner porous extraction electrode is greater than that of the outer cylindrical electrode.
Further, the sampling cone applies direct-current voltage, the tip of the sampling cone stretches into the strong focusing electrode assembly, a certain distance is reserved between the end face of the tip and the edge of the last group of through holes, and the formation of a quadrupole electric field is avoided.
The mass spectrometry ion extraction method improves the ion extraction efficiency under the atmospheric pressure by an additional special electric field, and the whole extraction of ions is realized by the following steps:
1) The direct current introduction process of ions comprises the steps of generating ions through an ESI source, applying higher direct current high voltage by a general ion source, applying a relatively lower voltage of +500V by a gas curtain plate by capillary needle voltage of about +3kV, and enabling the ions to pass through gas curtain holes under the drive of potential difference;
2) The atmospheric pressure transmission process of the ions is that the ions pass through the air curtain hole and enter the strong focusing assembly, and the assembly realizes special electric field distribution through simple direct current voltage difference and square holes on the structure. Here, the inner porous extraction electrode voltage of the strong focusing electrode assembly is kept equal to the air curtain voltage, which is also +500V, and the value is not too small relative to the air curtain voltage so as to avoid the loss caused by too large extraction kinetic energy of ions. In actual operation, the pressure difference between the two can be used for adjusting the kinetic energy of ions entering the strong focusing electrode assembly, and has influence on sensitivity. The outer cylinder electrode is set to be +100deg.V, penetrating potential through the through holes, a quadrupole electric field similar to radio frequency quadrupole rod is formed at each group of rotating through holes, and focusing can be realized by off-axis ions. In summary, the voltages of the shutter plate, the inner porous extraction electrode and the outer cylinder electrode are mainly matched, the difference delta E1 between the shutter plate and the inner porous extraction electrode is used for configuring ion kinetic energy, the formation of a solvent ion adduct common in an ESI source is reduced, and the difference delta E2 between the shutter plate and the inner porous extraction electrode is used for configuring quadrupole field intensity;
3) The ion enters the high-pressure transmission area through the beam diameter constraint and the voltage is set to +10V, potential drop is formed between the ion and the strong focusing electrode assembly, the ion is smoothly extracted, in this case, in addition to the radio-frequency voltage, a direct-current voltage of-10V is applied to each rod, and axial kinetic energy and radial constraint are jointly provided.
In conclusion, based on a series of potential drops, the constraint of quasi-quadrupole field and radio-frequency quadrupole field, the ions can be effectively extracted from atmospheric pressure to vacuum environment, and compared with the traditional sampling cone direct extraction, the efficiency can be effectively improved.
According to the invention, the extraction interface is improved, the distance between the air curtain hole and the sampling cone is increased, the ion extracted through the air curtain hole is focused by applying a space strong focusing electrostatic quadrupole electric field, and the density of the ion group is improved, so that the extraction efficiency of the sampling cone is improved, and the concentration of the solvent ion adduct is reduced.
The ion transport effect is closely related to the working gas pressure, that is, the mean free path of the ions, and generally, the higher the gas pressure, the smaller the mean free path, so in the prior art, ion transport is generally performed using multipole rods or ion funnels in the high gas pressure region (several torr). However, for the ion extraction in the atmospheric pressure environment, the multipole rod or the ion funnel has poor effect, and the cost is greatly increased due to the complex radio frequency power supply, and the problem of efficient ion extraction is not solved, so that the ion extraction device is less in use. The invention constructs a variable quadrupole field through simple direct current voltage and metal electrodes, improves the atmospheric pressure extraction of ions with lower cost, can reduce solvent ion adducts generated by an atmospheric pressure ion source by applying voltage, releases product ions, and can prevent neutral substances from depositing by a heated ion channel and reduce the background memory effect.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a schematic perspective view of a spatially strong focusing electrostatic quadrupole assembly;
FIG. 3 is a graph of two sets of aperture potential distributions for a spatially strongly focused electrostatic quadrupole assembly;
FIG. 4 is a graph showing the potential trend of the atmospheric pressure ion extraction interface device of the present invention;
FIG. 5 is a schematic diagram of the structure of an embodiment 1 based on atmospheric pressure mass spectrometry of the present invention;
FIG. 6 is a schematic diagram of the structure of an embodiment 2 based on atmospheric pressure mass spectrometry of the present invention;
In the figure, 1-ion source, 2-air curtain cavity, 201-air curtain plate, 202-air curtain hole, 203-slit, 204-air curtain gas, 3-strong focusing electrode assembly, 301-heating jacket, 302-outer cylinder electrode, 303-inner porous extraction electrode, 304-second set of through holes, 305-first set of through holes, 4-sampling cavity, 401-first-stage vacuum cavity, 402-sampling cone, 403-backing pump, 404-high pressure ion transmission assembly, 405-second differential hole, 5-ion optical assembly.
Detailed Description
The invention is described in further detail below in conjunction with the drawings of the specification to provide a better understanding of the present technical solution.
As shown in fig. 1, the atmospheric pressure vacuum interface structure of the ion extraction device for mass spectrometry of the present invention comprises an ion source 1, an air curtain chamber 2, a sampling chamber 4 and an ion optical assembly 5, which are sequentially arranged, wherein the sampling chamber 4 is a primary vacuum chamber 401, and the ion source 1 comprises ESI, APCI, etc. for generating ions, and also generates some neutral particles. An air curtain chamber 2 for the removal of neutral solvent molecules or other neutral particles. In conventional air curtain-sampling cone interface designs, typically either the needle on ESI source is high voltage or the discharge needle on APCI source is high voltage, the air curtain plate 201 is dc voltage, and the potential field between the two directs ions through the air curtain aperture 202 and then through the sampling cone 402 into the mass spectrometry ion delivery system. The disadvantage of this design is that ions generated by the ion source are extracted only by means of a potential field generated by the two terminal voltages and vacuum negative pressure, the efficiency is low, and most of the ions do not enter the mass spectrum ion optical system.
In the present invention, a strong focusing electrode assembly 3 is disposed within the air curtain chamber 2 between the air curtain plate 2 and the sampling cone 402. The strong focusing electrode assembly 3 comprises a heating sleeve 301, an outer cylinder electrode 302 and an inner porous extraction electrode 303, wherein the heating sleeve 301 is arranged on the surface of the outer cylinder electrode 302, and the heating mode can be a whole heating sleeve or a heating sheet stuck to the heating sleeve or other conventional heating modes. The outer cylinder electrode 302 is a stainless steel hollow electrode, the inner porous extraction electrode 303 is also a stainless steel electrode, and the outer cylinder electrode 302 and the inner porous electrode 303 are coaxially arranged structurally. As shown in fig. 2, which is a schematic diagram of a three-dimensional structure of the strong focusing electrode assembly 3, the front end of the inner porous electrode 303 is tapered and is matched with the taper of the air curtain plate to form a slit with a certain width, an air passage external interface is installed on one side of the air curtain cavity 2 and is used for introducing air curtain air 204, then the air curtain air 204 is reversely blown out of the air curtain hole 202 through the slit 203, neutral solvent molecules can be reduced to enter the vacuum interface to a certain extent, and in addition, the heating sleeve 301 of the outer cylinder electrode 302 covers the taper hole part to enable the taper hole to be in a hot state. In the middle position of the inner porous extraction electrode 303, a plurality of groups of through holes are distributed, 4 groups of through holes are drawn in the figure, a first group of through holes 305 are positioned at a certain distance downstream of the electrode cone, the shape of the holes can be rectangular or square, four holes are uniformly distributed along the circumference of the electrode, namely, two adjacent holes are 90 degrees, a second group of through holes 304 are positioned at a certain position downstream of the first group of through holes 305, and also four rectangular holes or square holes distributed along the circumference are correspondingly rotated by 45 degrees relative to the first group of through holes 305, and the positions of the holes of the second group of through holes 304 are correspondingly distributed. The distribution of the latter two sets of rectangular holes is distributed in a similar design. If more sets of rectangular holes are designed, the distribution of rectangular holes is also based on this approach.
The specific installation relationship of the strong focusing electrode assembly is shown in fig. 2, and the outer cylinder electrode 302 and the inner porous extraction electrode 303 are coaxially installed with a certain thickness gap between them for electric field insulation. In actual operation, the two electrodes apply a dc voltage of a certain magnitude, wherein the inner porous extraction electrode 303 with a conical sampling port provides an axial potential field of ions, and the radial potential field is provided by the outer cylinder electrode 302 and the inner porous extraction electrode 303.
The potential field profile of the strongly focused electrode assembly is plotted by ion optics software SIMION, as shown in fig. 3. For convenience of explanation, two voltage values are set randomly for the two electrodes, for example, the inner porous extraction electrode 303 is 500V and the outer cylinder electrode 302 is 100V, so that a certain voltage difference is formed. If the rectangular holes are not formed, two electrodes are respectively applied with certain voltage, and the formed electric field is mainly between the gaps of the two electrodes, so that the influence on the motion constraint of ions is negligible. In the invention, due to the existence of rectangular holes or square holes, the electric field of the outer cylinder electrode can be transmitted to an internal ion channel through the rectangular holes or square holes, as shown in the electric potential distribution of figure 3, the left figure shows the cross-section electric potential field distribution of the first group of through holes or square holes, four uniformly distributed rectangular holes or square holes, and the electric field permeation forms a symmetrical electric potential field. The right plot then shows the cross-sectional potential field distribution for a second set of rectangular or square holes, as opposed to the left plot, with the potential field difference being primarily 45 degrees rotated in the direction of each osmotic electric field, which corresponds to the hole location. Therefore, the function similar to a radio-frequency quadrupole rod is realized through the design of electrostatic fields of a plurality of groups of holes. Ions pass through the air curtain holes 202 and then enter the inner porous electrode 303, the ion tracks are divergent, after an electric field is applied, off-axis ions are far away from the electrode wall surface and are converged at the axial position under the action of a quadrupole field, and the design of a plurality of groups of rectangular holes is used for strongly focusing different divergent positions of the ion beam, so that the beam diameter of the ion beam is compressed as much as possible, and the ion extraction amount of the sampling cone 402 is improved.
In addition, since the strong focusing electrode assembly 3 is located in the air curtain chamber 2 as an ion channel, besides the ion focusing function, the solvent removal problem needs to be considered, and although the air curtain air blowback can remove most of neutral solvent molecules to enter the vacuum interface, part of solvent or solvent ion adducts enter the strong focusing electrode assembly 3, therefore, a heating device is also needed to be configured, wherein the heating of the bevel part of the inner porous extraction electrode 303 is used for preventing solvent deposition, and the heating sleeve 301 on the surface of the outer cylinder electrode 302 mainly heats the electrode to provide a certain heat radiation or thermal contact to prevent the solvent from depositing on the surface of the electrode, thereby causing a background memory effect. For the removal of solvent ion adducts, chemical bonds between the solvent and the ions are broken due to the presence of an electric field, gradually releasing the ions.
After the ions pass through the strong focusing electrode assembly 3, the ions are extracted through the sampling cone 402, the sampling cone 402 is made of stainless steel, the aperture is in the range of 0.5mm-1mm, the vacuum difference and the ion extraction function are realized, the sampling cone 402 applies direct current voltage, and an ion transmission focusing channel is formed by the sampling cone 402 and the potential field formed by the strong focusing electrode assembly 3 at the front end. In addition, in order to prevent neutral molecules from depositing on the surface of the sampling cone 402, the tip end portion of the sampling cone 402 is extended into the strong focusing electrode assembly, and the internal high temperature is transferred to the surface of the cone through radiation, and meanwhile, the focused and compressed ion beam can be extracted at maximum efficiency, but the axis position of the tip end does not exceed the tail end of the last group of rectangular holes, so that the formation of a quadrupole field is not influenced.
Ions pass through the sampling cone 402 and enter the sampling cavity 4, taking 0.5mm of the taper hole of the sampling cone 402 as an example, vacuum air pressure is reduced from atmospheric pressure to about several torr by an external backing pump 403, a high-air pressure ion transmission assembly 404 is arranged in the sampling cavity 4, ion beams passing through the sampling cone 402 are collisional cooled, and the number of ions entering a next stage system is increased. The high gas pressure ion transport assembly 404 may be a variety of types of ion transport systems, such as quadrupole rods, hexapole rods, octapole rods, ion hoppers, or other types of transport systems. In the schematic structure of fig. 1, a quadrupole rod with a pointed tip is configured, and is matched with the cone angle of the sampling cone 402, radio frequency voltage is applied to the quadrupole rod, so that cooling focusing of an ion beam is realized under the collision effect of background gas. The ion beam passes through the second differential aperture 405 and enters the following ion optics assembly 5.
In order to better illustrate the working principle of the atmospheric pressure ion extraction interface of the present invention, it can be analyzed in terms of electric field variation. Fig. 4 is a potential trend chart of the interface, wherein the ion source adopts a common electrospray ion source, and positive ions are taken as examples (potential trends of negative ions are opposite), and voltages shown in the chart are common values without absolute limitation, and are only used for illustrating the invention. The potential is gradually reduced from the ion source capillary needle voltage of about +3kv, the high pressure ion transport assembly 404 voltage is-10V, and the potential drops to about 3kV to ensure that there is a sufficient potential difference to transport ions from the ion source region to the instrument vacuum system. The voltage of the shutter plate 201 is +500V, which matches the capillary voltage for ion guiding. The voltage of the inner porous extraction electrode 303 of the strong focusing electrode assembly 3 is kept equal to the voltage of the shutter plate 201, and is also +500V, which is not too small relative to the voltage of the shutter plate 201, so as to avoid the loss caused by too large extraction kinetic energy of ions. The outer barrel electrode 302 is set to +100deg.V, with a through-hole penetration potential, creating a quadrupole electric field resembling a radio frequency quadrupole at each set of through-holes for divergent ion beam focusing. The ion beam is focused by the electrostatic quadrupole field and is extracted by the sampling cone 402, the voltage of the sampling cone 402 is set to +10v, a potential drop is formed between the sampling cone and the strong focusing electrode assembly 3, ions are smoothly extracted into the high-pressure ion transmission assembly 404, and here, in the example of a radio-frequency quadrupole rod with a pointed tip, a direct-current voltage of-10V is applied to each rod except the radio-frequency voltage. In conclusion, based on a series of potential drops, ions can be effectively extracted from atmospheric pressure to vacuum environment, and compared with the traditional sampling cone direct extraction, the efficiency can be greatly improved.
Example 1
The device is used as an atmospheric pressure ion extraction interface of an atmospheric pressure mass spectrum, as shown in fig. 5, an ion beam bound by an electrostatic field enters a sampling cavity through a sampling cone, ion collision cooling is carried out by adopting a quadrupole rod with a pointed tip, radio frequency voltage is applied to bind radial movement of ions, and the external connection of a backing pump maintains the vacuum degree of about 2 torr. The ions then pass through a second differential aperture into the high pressure ion transport assembly 5, in this example configured with rf quadrupoles, the partial vacuum being maintained by a molecular pump at a vacuum level of around 10 -2 torr. Ions are focused and transported into the final stage vacuum chamber, which is the mass analyzer of the mass spectrum.
Example 2
As shown in fig. 6, this example is also based on atmospheric pressure mass spectrometry. Ions are extracted by the sampling cone into the sampling cavity after passing through the strong focusing electrode assembly 3, the difference is that the rear end of the sampling cone 402 is directly connected with another cone, which is called an extraction cone herein, and the extraction cone applies direct current voltage as well, the function of which comprises providing vacuum difference and an ion channel, and the vacuum degree between the two cones is maintained at about 2torr as well, wherein the aperture of the extraction cone is larger than that of the sampling cone 402. Downstream of the extraction cone, a pointed rf quadrupole is arranged for collisional cooling of the ions. Ions pass through the differential aperture and finally enter the large chamber in which the mass analyzer is located. Examples 1 and 2 each include a three-stage differential system, for such atmospheric pressure sample-injection mass spectrometry systems, sometimes to reduce the decreasing gradient of vacuum pressure, the differential progression may be increased, preventing sudden changes in gas pressure from affecting ion transport efficiency.
Claims (7)
1. The mass spectrometry ion extraction device is characterized by comprising an ion source (1), an air curtain cavity (2), a sampling cavity (4) and an ion optical component (5) which are sequentially arranged;
an ion source (1) for generating ions of an object to be measured;
the air curtain cavity (2) comprises an air curtain plate (201) at the inlet end, an air curtain hole (202) is formed in the middle of the air curtain plate (201), a branch circuit is arranged on the side wall of the air curtain cavity (2) for providing air curtain air (204), a strong focusing electrode assembly (3) is arranged in the air curtain cavity (2), a slit (203) for allowing air curtain air to pass through is formed between one end of the strong focusing electrode assembly (3) close to the air curtain hole (202) and the inner wall of the air curtain plate (201), the strong focusing electrode assembly (3) comprises a heating sleeve (301), an outer cylinder electrode (302) and an inner porous extraction electrode (303), the heating sleeve (301), the outer cylinder electrode (302) and the inner porous extraction electrode (303) are coaxially arranged, the inner porous extraction electrode (303) is arranged in the outer cylinder electrode (302) and provided with a conical inlet end, the conical inlet end extends out of the outer cylinder electrode (302), and the heating sleeve (301) is arranged on the outer surface of the outer cylinder electrode (302) and extends to the outer surface of the conical inlet end of the inner porous extraction electrode (303), and the conical inlet end of the heating sleeve is matched with the conical taper of the air curtain plate (201).
The sampling cavity (4) comprises a sampling cone (402) and a high-pressure ion transmission assembly (404), a second differential hole (405) is formed in the outlet end of the sampling cavity (4), the ion optical assembly (5) is arranged corresponding to the second differential hole (405), and an interface external backing pump (403) is arranged on the side edge of the sampling cavity (4).
2. The mass spectrometry ion extraction device according to claim 1, wherein the surface of the inner porous extraction electrode (303) is provided with a first group of through holes (305) and a second group of through holes (304), the first group of through holes (305) and the second group of through holes (304) are sequentially provided with a plurality of groups at intervals, and the first group of through holes (305) and the second group of through holes (304) are rectangular holes or square holes.
3. The mass spectrometry ion extraction device of claim 2, wherein the first set of through holes (305) and the second set of through holes (304) are each provided with four rectangular or square holes and are each uniformly distributed around the circumference of the inner porous extraction electrode (303), the adjacent rectangular or square holes in the first set of through holes (305) are each disposed at 90 ° and the radial positions of the rectangular or square holes in the second set of through holes (304) are each rotated 45 °.
4. The mass spectrometry ion extraction device of claim 2, wherein the space between adjacent holes in each set of through holes is greater than the size of a single hole, and the pitch sizes of different sets are the same or different, and the pitch sizes of the same sets are the same.
5. The mass spectrometry ion extraction apparatus of claim 1, wherein the outer cylindrical electrode (302) and the inner porous extraction electrode (303) are each applied with a direct current voltage, and the voltage of the inner porous extraction electrode (303) is greater than the voltage of the outer cylindrical electrode (302).
6. A mass spectrometry ion extraction arrangement according to claim 1, wherein the sampling cone (402) is applied with a dc voltage and the tip of the sampling cone (402) extends into the strongly focusing electrode assembly (3) with a distance between the tip end face and the edge of the last set of through holes.
7. The mass spectrometry ion extraction method is characterized in that the extraction method improves the ion extraction efficiency under the atmospheric pressure through an additional special electric field, and the ion extraction is realized through the following steps:
1) The direct current introduction process of ions comprises the steps of generating ions through an ion source, applying direct current high voltage by the ion source, wherein the voltage of a capillary spray needle is higher than that of an air curtain plate, and the ions pass through an air curtain hole under the driving of potential difference;
2) The atmospheric pressure transmission process of the ions comprises the steps that the ions pass through an air curtain hole to enter a strong focusing assembly, and special electric field distribution is realized by a simple direct current voltage difference and a structural through hole of the strong focusing assembly, wherein the voltage of an inner porous extraction electrode of the strong focusing electrode assembly is kept equal to the voltage value of an air curtain plate, the voltage difference delta E1 between the air curtain plate and the inner porous extraction electrode is used for configuring ion kinetic energy, the formation of common solvent ion adducts in an ESI source is reduced, and the voltage difference delta E2 between the inner porous extraction electrode and an outer cylinder electrode is used for configuring quadrupole field intensity;
3) And in the high-pressure ion transmission process, ions enter a high-pressure transmission area through a sampling cone after being restrained by a beam diameter, and form potential drop with the strong focusing electrode assembly, so that the ions are smoothly extracted.
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