Mass spectrometry ion extraction device and method

Abstract

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

[0001] The invention belongs to the technical field of mass spectrometry analysis, and in particular relates to a mass spectrometry analysis ion extraction device and method. Background Art

[0002] The samples or analytes used for analysis in the mass spectrometer are usually ionized in the atmospheric environment, and then the ions are introduced into the vacuum chamber of the mass spectrometer. This type of atmospheric pressure ion source has a core advantage in sample ionization, but to introduce ions from the atmospheric pressure ion source into the vacuum chamber, it is usually necessary to configure an excellent interface between the ion source and the vacuum chamber for efficient ion extraction. Taking the currently widely used liquid phase tandem mass spectrometry (LC-MS / MS) as an example, common atmospheric pressure ion sources include electrospray ionization (ESI), atmospheric pressure chemical ionization source (APCI), etc. After the sample is ionized, ions and other neutral substances are generated. In particular, the ESI ion source generates charged droplets through a high-voltage spray needle, and gradually removes the solvent by heating the droplets to form ions, and extracts the sample ions through a vacuum interface. According to the results of literature research, most of the ion loss occurs at the vacuum interface during the ion transmission process from atmospheric pressure to vacuum, and the actual extraction efficiency does not exceed 1% at most, so the design of the vacuum interface is crucial to the sensitivity of the instrument.

[0003] As explained above, ESI and APCI sources operate at atmospheric pressure, that is, in addition to the ions of the substance to be ionized, there are also many neutral molecules or other uncharged particles. Due to the extraction of vacuum negative pressure, these substances will also enter the vacuum interface with the ions, and may eventually reach the mass spectrometer detector, resulting in reduced mass spectrometry sensitivity. Taking the most commonly used ESI source as an example, in addition to ions, the substances produced by its ionization also include more solvent molecules or solvent ion adducts, and the ion loss at the vacuum interface is relatively large.

[0004] There are two main designs of commercial LC-MS / MS vacuum interfaces: sampling cone and capillary. For example, the ESI ion source described in patent EP2260503B1 has a charged capillary as the vacuum interface. The charged capillary achieves vacuum differential and provides an ion transmission channel. Patent US6759650 provides a vacuum interface solution for the sampling cone. Ions enter the ion transmission system after passing through the air curtain plate, sampling cone, and extraction cone in the atmospheric pressure environment. Compared with the capillary design, the advantages of the sampling cone design include: it is not easy to cause sample blockage; it is convenient to replace the sampling cone; the processing cost of the sampling cone is low; the sampling cone has better thermal conductivity, which can avoid the condensation of samples in the free jet expansion zone to a certain extent. However, most of the current solutions based on the sampling cone adopt a direct extraction method, that is, the voltage on the ESI needle and the sampling cone or the air curtain plate is guided, and the ion injection is performed by external negative pressure absorption. This method is less efficient. Therefore, patent DE 102004045706A1 proposed a new design, adding an auxiliary electrode to the ion source to improve the ion extraction efficiency of the interface, but the auxiliary electrode will reduce the desolvation process time of the ions, and many ions will be annihilated on the air curtain plate. In addition, there are some designs that increase the ion extraction efficiency by increasing the aperture of the sampling cone. This method is feasible, but it requires increasing the load of the vacuum pump, and the cost will increase simultaneously in commercial development. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a mass spectrometry ion extraction device and method. Based on the current air curtain-sampling cone vacuum interface design, an ion channel is provided to assist heating and spatial strong focusing of the electrostatic quadrupole electric field, so as to achieve a function similar to radio frequency cooling and focusing in an ingenious and simple way, thereby achieving efficient ion extraction and improving the sensitivity of the mass spectrometer. This is specifically achieved through the following technical solutions:

[0006] The mass spectrometry ion extraction device comprises an ion source, an air curtain chamber, a sampling chamber and an ion optical component arranged in sequence;

[0007] Ion source: used to generate ions of the substance to be tested; including atmospheric pressure sources such as electrospray source ESI, atmospheric pressure chemical ionization source APCI, etc.

[0008] Air curtain chamber: Its inlet end is composed of a conical air curtain plate, an air curtain hole is arranged in the middle of the air curtain plate, a branch is arranged on the side wall of the air curtain chamber to provide air curtain gas, a strong focusing electrode assembly is arranged in the air curtain chamber, and a slit for the air curtain gas to pass through 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, so that the air curtain gas can be blown back out of the air curtain hole through the slit;

[0009] Sampling chamber: includes a sampling cone and a high-pressure ion transmission component. A second differential hole is provided at the outlet end of the sampling chamber. The ion optical component is provided corresponding to the second differential hole. An interface for an external front pump is provided on the side of the sampling chamber. The ion optical component includes a transmission system such as a quadrupole, a hexapole, an octopole, and an ion funnel.

[0010] Further, the strong focusing electrode assembly includes a heating sleeve, an outer cylindrical electrode and an inner porous extraction electrode, the heating sleeve, the outer cylindrical electrode and the inner porous extraction electrode are coaxially mounted, the inner porous extraction electrode is arranged inside the outer cylindrical electrode and has a tapered inlet end, the tapered inlet end extends out of the outer cylindrical electrode, the heating sleeve is mounted on the outer surface of the outer cylindrical electrode and extends to the outer surface of the tapered inlet end of the inner porous extraction electrode, the taper of the tapered inlet end matches the taper of the air curtain plate. The heating sleeve is used to heat the tapered inlet ends of the outer cylindrical electrode and the inner porous extraction electrode to prevent the deposition of neutral substances.

[0011] Furthermore, a first group of through holes and a second group of through holes are distributed on the surface of the inner porous extraction electrode, and the first group of through holes and the second group of through holes are arranged in multiple groups in sequence and are rectangular holes or square holes.

[0012] Furthermore, the first group of through holes and the second group of through holes are both provided with four rectangular holes or square holes, which are evenly distributed around the circumference of the inner porous extraction electrode. Adjacent rectangular holes or square holes in the first group of through holes are arranged at 90°, and the radial positions of each rectangular hole or square in the second group of through holes are rotated 45°.

[0013] Furthermore, the space between adjacent holes in each group of through holes is larger than the size of a single hole, the hole spacings in different groups are the same or different, and the hole spacings in the same group are the same.

[0014] Furthermore, direct current voltages are applied to the outer cylindrical electrode and the inner porous extraction electrode respectively, and the voltage of the inner porous extraction electrode is greater than the voltage of the outer cylindrical electrode.

[0015] Furthermore, a DC voltage is applied to the sampling cone, and the tip of the sampling cone extends into the strong focusing electrode assembly, leaving a certain distance between the tip end face and the edge of the last set of through holes to avoid interfering with the formation of the quadrupole electric field.

[0016] Mass spectrometry ion extraction method, which uses an additional special electric field to improve the ion extraction efficiency under atmospheric pressure. The entire extraction of ions is achieved through the following steps:

[0017] 1) DC ion introduction process: Ions are generated through the ESI source. Generally, the ion source applies a high DC high voltage. The capillary needle voltage is about +3kV. The air curtain plate applies a relatively low voltage of +500V. The ions pass through the air curtain hole driven by the potential difference.

[0018] 2) Atmospheric pressure transmission process of ions: ions pass through the air curtain holes and enter the strong focusing assembly, which realizes a special electric field distribution through a simple DC voltage difference and square holes in the structure. Here, the voltage of the inner porous extraction electrode of the strong focusing electrode assembly is kept equal to the voltage of the air curtain plate, which is also +500V. This value should not be too small relative to the voltage of the air curtain plate, so as to avoid excessive loss of ion extraction kinetic energy. In actual operation, the pressure difference between the two can be used to adjust the kinetic energy of ions entering the strong focusing electrode assembly, which has an impact on sensitivity. The outer cylinder electrode is set to +100V, and through the through-hole penetration potential, a quadrupole electric field similar to a radio frequency quadrupole is formed at each set of rotating through holes, so that off-axis ions can be focused. In short, the main thing here is to match the voltages of the air curtain plate, the inner porous extraction electrode and the outer cylinder electrode. The difference ΔE1 between the former two is used to configure the kinetic energy of the ions and reduce the formation of solvent ion adducts commonly seen in ESI sources. The difference ΔE2 between the latter two is used to configure the quadrupole field strength;

[0019] 3) High-pressure transmission process of ions: After passing through the beam diameter constraint, the ions enter the high-pressure transmission region through the sampling cone. The voltage is set to +10V, forming a potential drop with the strong focusing electrode assembly, and the ions are successfully extracted. Here, the tip-tipped RF quadrupole is taken as an example. In addition to the RF voltage, a DC voltage of -10V is applied to each rod to jointly provide axial kinetic energy and radial constraint.

[0020] In summary, based on a series of potential drops, quadrupole-like fields and radio frequency quadrupole fields, ions can be effectively extracted from atmospheric pressure to vacuum environment, which can effectively improve efficiency compared to traditional direct extraction with a sampling cone.

[0021] 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, increases the density of the ion group, thereby improving the extraction efficiency of the sampling cone and reducing the concentration of solvent ion adducts.

[0022] The ion transmission effect is closely related to the working gas pressure, that is, it is related to the mean free path of the ions. Generally speaking, the higher the gas pressure, the smaller the mean free path. Therefore, in the existing technology, in the high pressure area (several Torr), multipoles or ion funnels are usually used for ion transmission. However, for ion extraction in an atmospheric pressure environment, the above-mentioned multipoles or ion funnels will also be very poor, and a complex radio frequency power supply must be configured, which greatly increases the cost and does not solve the problem of efficient ion extraction. Therefore, they are seldom used. The present invention constructs a variable quadrupole field through a simple DC voltage and a metal electrode to improve the atmospheric pressure extraction of ions at a lower cost. The application of voltage can reduce the solvent ion adducts produced by the atmospheric pressure ion source and release the product ions. At the same time, the heated ion channel can prevent the deposition of neutral substances and reduce the background memory effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the patent of this invention;

[0024] Figure 2 It is a schematic diagram of the three-dimensional structure of the spatial strong focusing electrostatic quadrupole assembly;

[0025] Figure 3 The potential distribution of two groups of openings of the spatially strongly focusing electrostatic quadrupole assembly;

[0026] Figure 4 This is a potential variation trend diagram of the atmospheric pressure ion extraction interface device of the present invention;

[0027] Figure 5 It is a structural schematic diagram of a specific example 1 based on atmospheric pressure mass spectrometry of the present invention patent;

[0028] Figure 6 It is a structural schematic diagram of a specific example 2 based on atmospheric pressure mass spectrometry of the present invention patent;

[0029] In the figure, 1-ion source, 2-air curtain chamber, 201-air curtain plate, 202-air curtain hole, 203-slit, 204-air curtain gas, 3-strong focusing electrode assembly, 301-heating sleeve, 302-outer tube electrode, 303-inner porous extraction electrode, 304-second group of through holes, 305-first group of through holes, 4-sampling chamber, 401-first vacuum chamber, 402-sampling cone, 403-fore stage pump, 404-high pressure ion transmission assembly, 405-second differential hole, 5-ion optical assembly. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings in order to better understand the technical solution.

[0031] like Figure 1 As shown, the schematic diagram of the atmospheric pressure vacuum interface structure of the mass spectrometer ion extraction device of the present invention includes an ion source 1, an air curtain chamber 2, a sampling chamber 4 and an ion optical component 5 arranged in sequence, wherein the sampling chamber 4 is a primary vacuum chamber 401, and the ion source 1 includes ESI, APCI, etc., which is used to generate ions and also generates some neutral particles. The air curtain chamber 2 is used to remove neutral solvent molecules or other neutral particles. In the traditional air curtain-sampling cone interface design, the spray needle on the ESI source is generally high voltage or the discharge needle on the APCI source is high voltage, and the air curtain plate 201 carries a DC voltage. The potential field between the two guides the ions to pass through the air curtain hole 202, and then pass through the sampling cone 402 to enter the mass spectrometer ion transmission system. The defect of this design is that the ions generated by the ion source are only extracted by the potential field generated by the two terminal voltages and the vacuum negative pressure, which is inefficient and most of the ions do not enter the mass spectrometer ion optical system.

[0032] In the present invention, a strong focusing electrode assembly 3 is arranged in the air curtain chamber 2, and is located between the air curtain plate 2 and the sampling cone 402. The strong focusing electrode assembly 3 includes a heating sleeve 301, an outer tube electrode 302, and an inner porous extraction electrode 303. The heating sleeve 301 is installed on the surface of the outer tube electrode 302. The heating method can be a whole heating sleeve or a heating plate attached or other conventional heating methods. The outer tube electrode 302 is a stainless steel hollow electrode, and the inner porous extraction electrode 303 is also a stainless steel electrode. Structurally, the outer tube electrode 302 and the inner porous electrode 303 are coaxially installed. Figure 2 This is a schematic diagram of the three-dimensional structure of the strong focusing electrode assembly 3. The front end of the inner porous electrode 303 is conical, matching the conical shape of the air curtain plate to form a slit of a certain width. On one side of the air curtain chamber 2, an external air path interface is installed for introducing the air curtain gas 204, and then the air curtain gas 204 is blown back out of the air curtain hole 202 through the slit 203, which can reduce the entry of neutral solvent molecules into the vacuum interface to a certain extent. In addition, the heating sleeve 301 of the outer tube electrode 302 covers the conical hole part, so that the conical hole is in a hot state. There are multiple groups of through holes distributed in the middle of the inner porous extraction electrode 303. Four groups are drawn in the figure for description. The first group of through holes 305 is located at a certain distance downstream of the electrode cone. The shape of the holes can be rectangular or square. Four holes are evenly distributed along the circumference of the electrode, that is, two adjacent holes are 90° apart. The second group of through holes 304 is located at a certain position downstream of the first group of through holes 305. They are also four rectangular holes or square holes distributed along the circumference. Relative to the first group of through holes 305, the radial positions of each hole of the second group of through holes 304 are rotated 45°. The distribution of the two groups of rectangular holes behind is similarly designed. If more groups of rectangular holes are designed, the distribution of the rectangular holes is also based on this method.

[0033] The specific installation relationship of the strong focusing electrode assembly is as follows Figure 2 As shown, the outer cylindrical electrode 302 and the inner porous extraction electrode 303 are coaxially installed, and there is a gap of a certain thickness between the two for electric field insulation. In actual operation, a certain DC voltage is applied to the two electrodes respectively, wherein the inner porous extraction electrode 303 with a conical sampling port provides an axial potential field for the ions, and the radial potential field is provided by the outer cylindrical electrode 302 and the inner porous extraction electrode 303 together.

[0034] The potential field distribution diagram of the strong focusing electrode assembly is shown in Figure 3As shown, it is drawn by ion optical software SIMION. For the convenience of explanation, two voltage values ​​are randomly set for the two electrodes, such as 500V for the inner porous extraction electrode 303 and 100V for the outer tube electrode 302, forming a certain voltage difference. If there is no rectangular hole, a certain voltage is applied to the two electrodes respectively, and the electric field formed is mainly between the gaps of the two electrodes, and the effect on the movement and binding of ions can be ignored. In the present invention, due to the presence of rectangular holes or square holes, the electric field of the outer tube electrode can be transmitted to the internal ion channel through the rectangular holes or square holes, such as Figure 3 Potential distribution, the left picture shows the cross-sectional potential field distribution of the first group of through holes or square holes, four evenly distributed rectangular holes or square holes, and the electric field penetrates to form a symmetrical potential field. Then the right picture shows the cross-sectional potential field distribution of the second group of rectangular holes or square holes. Compared with the left picture, the difference in the potential field is mainly that the direction of each penetration electric field is rotated 45°, which corresponds to the position of the hole. Therefore, through the electrostatic field design of multiple groups of holes, a function similar to that of a radio frequency quadrupole is achieved. The ions pass through the air curtain hole 202 and then enter the inner porous electrode 303. The ion trajectory will be more divergent. After the electric field is applied, the off-axis ions move away from the electrode wall under the action of the quadrupole field and converge at the axis position. The design of multiple groups of rectangular holes is used to strongly focus the different divergent positions of the ion beam, compress the beam diameter of the ion beam as much as possible, and increase the ion extraction amount of the sampling cone 402.

[0035] In addition, since the strong focusing electrode assembly 3 is located in the air curtain chamber 2, as an ion channel, in addition to the ion focusing function, the desolvation problem needs to be considered. Although the air curtain gas backflush can remove most of the neutral solvent molecules entering the vacuum interface, there are still some solvents or solvent ion adducts that enter the strong focusing electrode assembly 3. Therefore, a heating device is also required, wherein the cone mouth portion of the inner porous extraction electrode 303 is heated to prevent solvent deposition; the heating sleeve 301 on the surface of the outer tube electrode 302 mainly heats the electrode, provides a certain amount of thermal radiation or thermal contact, and prevents the solvent from being deposited on the electrode surface, causing a background memory effect. For the removal of solvent ion adducts, due to the presence of the electric field, the chemical bonds between the solvent and the ions will be broken, and the ions will be gradually released.

[0036] After the ions are acted upon by the strong focusing electrode assembly 3, they are extracted by the sampling cone 402. The sampling cone 402 is made of stainless steel with an aperture in the range of 0.5 mm to 1 mm. It plays the role of vacuum differential and ion extraction. A DC voltage is applied to the sampling cone 402 itself, and the electric potential field formed by the strong focusing electrode assembly 3 at the front end forms a transmission focusing channel for the ions. In addition, in order to prevent the deposition of neutral molecules on the surface of the sampling cone 402, the tip of the sampling cone 402 is extended into the strong focusing electrode assembly, and the high temperature inside is transmitted to the surface of the cone in the form of radiation. At the same time, the ion beam after focusing and compression can be extracted with maximum efficiency. However, the tip axis position does not exceed the end of the last group of rectangular holes to avoid affecting the formation of the quadrupole field.

[0037] The ions pass through the sampling cone 402 and enter the sampling chamber 4. Taking the sampling cone 402 with a cone hole of 0.5 mm as an example, the vacuum pressure is reduced from atmospheric pressure to about several Torr by an external front pump 403. A high-pressure ion transmission component 404 is configured in the sampling chamber 4 to perform collision cooling on the ion beam passing through the sampling cone 402, thereby increasing the number of ions entering the next-stage system. The high-pressure ion transmission component 404 can be various types of ion transmission systems, such as a quadrupole, a hexapole, an octopole, an ion funnel or other types of transmission systems. Figure 1 In the schematic diagram, the quadrupole with a sharpened tip is configured to match the cone angle of the sampling cone 402. The quadrupole applies a radio frequency voltage to achieve cooling and focusing of the ion beam under the collision of the background gas. The ion beam passes through the second differential aperture 405 and enters the ion optical component 5 behind.

[0038] In order to better explain the working principle of the atmospheric pressure ion extraction interface of the present invention, it can be analyzed from the perspective of electric field changes. Figure 4 : is the potential change trend diagram of the interface. Here, the ion source adopts a common electrospray ion source. Taking positive ions as an example (the potential trend of negative ions is opposite), the voltage shown in the figure is a common value, without absolute limitation, and is only used to illustrate the present invention. The potential gradually decreases from the capillary needle of the ion source. The capillary needle voltage is about +3kV, the voltage of the high-pressure ion transmission component 404 is -10V, and the potential drop is nearly 3kV to ensure that there is enough potential difference to transmit ions from the ion source area to the instrument vacuum system. The voltage of the air curtain plate 201 is +500V, which matches the capillary voltage for ion guidance. The voltage of the inner porous extraction electrode 303 of the strong focusing electrode assembly 3 is kept equal to the voltage value of the air curtain plate 201, which is also +500V. This value should not be too small relative to the voltage of the air curtain plate 201, so as to avoid excessive kinetic energy of ion extraction and loss. The outer tube electrode 302 is set to +100V, and through the through-hole penetration potential, a quadrupole electric field similar to a radio frequency quadrupole is formed at each group of through holes for focusing the divergent ion beam. The ion beam is focused by the electrostatic quadrupole field and extracted by the sampling cone 402. The voltage of the sampling cone 402 is set to +10V, forming a potential drop with the strong focusing electrode assembly 3, and the ions are smoothly extracted into the high-pressure ion transmission assembly 404. Here, the radio frequency quadrupole with a sharpened tip is taken as an example. In addition to the radio frequency voltage, a DC voltage of -10V is applied to each rod. In summary, based on a series of potential drops, ions can be effectively extracted from atmospheric pressure to a vacuum environment, which can greatly improve efficiency compared to traditional direct extraction with a sampling cone.

[0039] Example 1

[0040] The device of the present invention is used as an atmospheric pressure ion extraction interface for atmospheric pressure mass spectrometry, such as Figure 5The ion beam bounded by the electrostatic field enters the sampling cavity through the sampling cone. This part uses a sharpened quadrupole for ion collision cooling, applies radio frequency voltage to constrain the radial motion of the ions, and connects to an external front pump to maintain a vacuum of about ~2 torr. Then the ions pass through the second differential hole and enter the high-pressure ion transmission component 5. In this example, a radio frequency quadrupole is configured. The vacuum in this part is maintained by a molecular pump, and the vacuum degree is about ~10 -2 The ions are focused and transmitted into the final vacuum chamber, which is the mass analyzer of the mass spectrometer.

[0041] Example 2

[0042] like Figure 6 As shown, this example is also based on atmospheric pressure mass spectrometry. After the ions pass through the strong focusing electrode assembly 3, they are extracted by the sampling cone and enter the sampling cavity. The difference is that the rear end of the sampling cone 402 is directly connected to another cone, which is called the extraction cone. The extraction cone also applies a DC voltage, and its functions include providing vacuum differential and ion channels. The vacuum degree between the two cones is also maintained at about ~2torr, and the aperture of the extraction cone is larger than the sampling cone 402. Downstream of the extraction cone, a radio frequency quadrupole with a sharpened tip is configured for collision cooling of ions. The ions pass through the differential hole and finally enter the large chamber where the mass analyzer is located. Examples 1 and 2 both include a three-stage differential system. For this type of atmospheric pressure injection mass spectrometry system, sometimes in order to reduce the gradient of the vacuum pressure reduction, the differential number may be increased to prevent the sudden change in air pressure from affecting the ion transmission efficiency.

Claims

1. A mass spectrometry ion extraction device, characterized in that: The device comprises an ion source (1), an air curtain chamber (2), a sampling chamber (4) and an ion optical component (5) which are arranged in sequence; Ion source (1): used to generate ions of the substance to be analyzed; An air curtain chamber (2): the inlet end of which is composed of a conical air curtain plate (201); an air curtain hole (202) is arranged in the middle of the air curtain plate (201); a branch is arranged on the side wall of the air curtain chamber (2) to provide air curtain gas (204); a strong focusing electrode assembly (3) is arranged in the air curtain chamber (2); a slit (203) for the air curtain gas 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 tube electrode (302) and An inner porous extraction electrode (303), wherein the heating sleeve (301), the outer cylindrical electrode (302) and the inner porous extraction electrode (303) are coaxially mounted, the inner porous extraction electrode (303) is arranged inside the outer cylindrical electrode (302) and has a conical inlet end, the conical inlet end extends out of the outer cylindrical electrode (302), the heating sleeve (301) is mounted on the outer surface of the outer cylindrical electrode (302) and extends to the outer surface of the conical inlet end of the inner porous extraction electrode (303), and the taper of the conical inlet end matches the taper of the air curtain plate (201); The sampling chamber (4) comprises a sampling cone (402) and a high-pressure ion transmission component (404); a second differential hole (405) is arranged at the outlet end of the sampling chamber (4); an ion optical component (5) is arranged corresponding to the second differential hole (405); and an interface for connecting an external front pump (403) is arranged on the side of the sampling chamber (4).

2. The mass spectrometry ion extraction device according to claim 1, characterized in that A first group of through holes (305) and a second group of through holes (304) are distributed on the surface of the inner porous extraction electrode (303); the first group of through holes (305) and the second group of through holes (304) are arranged in multiple groups in sequence and at intervals; 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 according to claim 2, characterized in that The first group of through holes (305) and the second group of through holes (304) are both provided with four rectangular holes or square holes, which are evenly distributed around the circumference of the inner porous extraction electrode (303); adjacent rectangular holes or square holes in the first group of through holes (305) are arranged at 90 degrees, and the radial positions of the rectangular holes or square holes in the second group of through holes (304) are all rotated 45 degrees.

4. The mass spectrometry ion extraction device according to claim 2, characterized in that The space between adjacent holes in each group of through holes is larger than the size of a single hole. The hole spacings in different groups are the same or different, and the hole spacings in the same group are the same.

5. The mass spectrometry ion extraction device according to claim 1, characterized in that A direct current voltage is applied to the outer cylindrical electrode (302) and the inner porous extraction electrode (303), respectively, and the voltage of the inner porous extraction electrode (303) is greater than the voltage of the outer cylindrical electrode (302).

6. The mass spectrometry ion extraction device according to claim 1, characterized in that A DC voltage is applied to the sampling cone (402), and the tip of the sampling cone (402) extends into the strong focusing electrode assembly (3), with a certain distance between the tip end surface and the edge of the last group of through holes.

7. A method for extracting ions by mass spectrometry, characterized in that: This extraction method uses an additional special electric field to improve the ion extraction efficiency under atmospheric pressure. The extraction of ions is achieved through the following steps: 1) DC ion introduction process: ions are generated by the ion source, which applies DC high voltage. The capillary needle voltage is higher than the air curtain plate voltage, and the ions pass through the air curtain hole driven by the potential difference. 2) Atmospheric pressure transmission process of ions: ions pass through the air curtain holes and enter the strong focusing assembly, which realizes a special electric field distribution through a simple DC voltage difference and a through hole in the structure. The voltage of the inner porous extraction electrode of the strong focusing electrode assembly is kept equal to the voltage of the air curtain plate. The voltage difference ΔE1 between the air curtain plate and the inner porous extraction electrode is used to configure the kinetic energy of the ions and reduce the formation of common solvent ion adducts in the ESI source. The voltage difference ΔE2 between the inner porous extraction electrode and the outer cylinder electrode is used to configure the quadrupole field strength. 3) High-pressure transmission process of ions: The ions pass through the beam diameter constraint, enter the high-pressure transmission area through the sampling cone, form a potential drop with the strong focusing electrode assembly, and the ions are successfully extracted.

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