Electron bombardment ionization source

Abstract

The invention discloses an electron bombardment ionization source, and relates to the technical field of ionization. The electron bombardment ionization source at least comprises a first ionization chamber, a second ionization chamber and a sample injection control piece, the first ionization chamber is provided with a first sample inlet; the second ionization chamber is communicated with the first ionization chamber, and the second ionization chamber is provided with a second sample inlet; the sample injection control piece is respectively communicated with the first sample injection port and the second sample injection port and is suitable for introducing a sample to be detected; the sample injection control piece is used for controlling the sample to be detected to enter the first ionization chamber and / or the second ionization chamber. According to the electron bombardment ionization source, the structure of the electron bombardment ionization source is improved, the adaptability of the electron bombardment ionization source to different samples is improved, the electron bombardment ionization source has four ionization modes, different ionization requirements can be met, and therefore the analysis requirements of different fields are met. In addition, the long service life and the high ionization efficiency of the ion source are effectively guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of ionization, in particular to an electron bombardment ionization source. Background Art

[0002] A mass spectrometer is a scientific instrument for analyzing the composition of chemical substances. It works by ionizing the molecules of the substance to be tested through certain means, and then screening and measuring the ions through an ion optical system. A mass spectrometer usually consists of an injection system, an ion source, a mass analyzer, a detector, a vacuum system, and an electronic control system.

[0003] The ion source is a key component in the mass spectrometer. Its function is to ionize the gaseous sample molecules introduced by the injection system into ions. The ionization of sample molecules is the primary step in mass spectrometry analysis. The performance of the ion source has a significant impact on many indicators of the instrument. Whether the sample molecules can be effectively ionized will directly affect important indicators such as the type of detectable substances, detection limit and sensitivity. The electron bombardment ionization source is a widely used ion source. Its basic principle is that the filament emits electrons, the accelerating electric field accelerates the electrons, and the high-energy electrons bombard the molecules of the analyte to ionize the molecules of the analyte.

[0004] In recent years, with the advancement of science and technology and the increase in application needs, higher requirements have been put forward for mass spectrometry detection. In practical applications, the samples to be tested are diverse, and different samples have different requirements for mass spectrometry ionization. For example, high-concentration, high-throughput injection samples require ionization sources with higher carrying capacity and better resistance to contamination, low-concentration samples require ionization sources with higher ionization efficiency, and unknown mixed samples require ionization sources for specific ionization to improve the accuracy of qualitative analysis.

[0005] The electron bombardment ionization source used in existing mass spectrometers is a universal single ionization chamber ionization source, which cannot perform different ionization modes for samples to be tested with different requirements. The electron bombardment ionization source has poor adaptability to different samples, which causes the ion source to be easily contaminated when used for high-concentration samples, and the ionization efficiency is not high enough for low-concentration samples, affecting the qualitative and quantitative accuracy. Summary of the invention

[0006] The main purpose of the present invention is to provide an electron bombardment ionization source, aiming to improve the adaptability of the electron bombardment ionization source to different samples to meet different ionization requirements.

[0007] To achieve the above object, the present invention provides an electron bombardment ionization source, comprising at least: A first ionization chamber is provided with a first injection port; a second ionization chamber, connected to the first ionization chamber, wherein the second ionization chamber is provided with a second injection port; and The sample injection control component is connected to the first sample injection port and the second sample injection port respectively and is suitable for introducing the sample to be tested. The sample injection control component is used to control the sample to be tested to enter the first ionization chamber and / or the second ionization chamber.

[0008] Optionally, the sample injection control component is a sample switching valve, and the sample switching valve is used to control the flow direction of the sample to be tested; and / or The volume of the first ionization chamber is greater than the volume of the second ionization chamber.

[0009] Optionally, the electron bombardment ionization source further includes a first filament group disposed in the first ionization chamber and a second filament group disposed in the second ionization chamber, and the first filament group and the second filament group each include two filaments disposed opposite to each other.

[0010] Optionally, the electron bombardment ionization source further includes an extraction component, the second ionization chamber is provided with a sample outlet, the extraction component is connected to the sample outlet and is suitable for being connected to a mass analyzer, and the extraction component is used to extract the fragment ions generated by ionization; the extraction component includes an extraction lens, a focusing lens and an ejection lens arranged in sequence at intervals, the extraction lens is used to extract the fragment ions from the sample outlet, the focusing lens is used to bunch the fragment ions, and the ejection lens is used to extract the fragment ions to the mass analyzer; and / or The electron bombardment ionization source further includes a repeller electrode, which is disposed in the first ionization chamber or constitutes a chamber wall on one side of the first ionization chamber, and is used to push the generated fragment ions toward the sample outlet.

[0011] Optionally, the electron bombardment ionization source has at least four working modes: high flux mode, high sensitivity mode, secondary ionization mode and qualitative mode; When the high-throughput mode is adopted, the sample injection control component controls the sample to be tested to be introduced into the first ionization chamber, and the first ionization chamber works so that the sample to be tested collides with electrons in the first ionization chamber; When the high-sensitivity mode is adopted, the sample injection control component controls the sample to be tested to be introduced into the second ionization chamber, and the second ionization chamber starts ionization work, so that the sample to be tested collides with electrons in the second ionization chamber; When the secondary ionization mode is adopted, the sample injection control component controls the sample to be tested to be introduced into the first ionization chamber, and the first ionization chamber and the second ionization chamber start ionization work at the same time, so that the sample to be tested collides in the first ionization chamber and the second ionization chamber successively; When the qualitative mode is adopted, the sample to be tested is a mixed sample, the injection control component controls the sample to be tested to be introduced into the first ionization chamber, the first ionization chamber starts the soft ionization mode and the electron energy gradually increases, and the second ionization chamber starts the hard ionization mode, so that the substances in the sample to be tested are gradually soft-ionized to form molecular ions, and then enter the second ionization chamber for hard ionization to generate fragment ions.

[0012] Optionally, when the qualitative mode is adopted, the electron energy of the first ionization chamber is 7eV~20eV, and is scanned from 7eV to 20eV with a scanning step of 0.1eV, and the electron energy of the second ionization chamber is 70eV.

[0013] Optionally, when the high-throughput mode is adopted, a zero potential voltage is applied to the first ionization chamber, and a negative voltage is applied to the second ionization chamber, so as to introduce fragment ions into the second ionization chamber.

[0014] Optionally, when the high-sensitivity mode is adopted, a positive voltage is applied to the first ionization chamber, and a zero potential voltage is applied to the second ionization chamber, so as to push the fragment ions into the second ionization chamber.

[0015] Optionally, when the secondary ionization mode is adopted, a zero potential voltage is applied to the first ionization chamber, and a negative voltage is applied to the second ionization chamber, so that fragment ions enter from the first ionization chamber into the second ionization chamber.

[0016] Optionally, when the qualitative mode is adopted, a zero potential voltage is applied to the first ionization chamber, and a negative voltage is applied to the second ionization chamber, so as to introduce molecular ions into the second ionization chamber.

[0017] In the technical solution of the present invention, the electron bombardment ionization source includes a first ionization chamber, a second ionization chamber and an injection control component; the first ionization chamber is provided with a first injection port; the second ionization chamber is connected to the first ionization chamber, and the second ionization chamber is provided with a second injection port; the injection control component is respectively connected to the first injection port and the second injection port and is suitable for introducing the sample to be tested, and the injection control component is used to control the sample to be tested to enter the first ionization chamber and / or the second ionization chamber. It can be understood that the present invention improves the structure of the electron bombardment ionization source, determines the sample to be tested to flow to the first ionization chamber or the second ionization chamber through the injection control component, and sets two independently controllable ionization chambers to set different ionization modes, which greatly improves the adaptability of the electron bombardment ionization source to different samples, and suitable ionization methods can be used for different samples to meet different ionization requirements, thereby meeting the analysis requirements of different fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0019] Figure 1 It is a structural schematic diagram of an embodiment of an electron bombardment ionization source of the present invention; Figure 2 This is a schematic diagram of the application of an electron bombardment ionization source in an embodiment of the present invention in a high flux mode; Figure 3 It is a schematic diagram of the application of an embodiment of the electron bombardment ionization source of the present invention in a high sensitivity mode; Figure 4 It is a schematic diagram of the application of an embodiment of the electron bombardment ionization source of the present invention in a secondary ionization mode; Figure 5 This is a schematic diagram of the application of an electron bombardment ionization source in one embodiment of the present invention in a qualitative mode.

[0020] Description of Figure Numbers: 10. First ionization chamber; 20. Second ionization chamber; 30. Sample injection control unit; 10a. First injection port; 20a. Second injection port; 11. First filament group; 12. Repeller electrode; 21. Second filament group; 20b. Sample outlet; 41. Extraction lens; 42. Focusing lens; 43. Expulsion lens; a. Electrons; b. Sample to be tested; c. Fragment ions; b1. First substance; b2. Second substance; c1. Molecular ions of the first substance; c2. Mixed fragment ions.

[0021] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0026] The invention provides an electron bombardment ionization source.

[0027] Reference Figure 1 and Figure 2 In one embodiment of the present invention, the electron bombardment ionization source includes a first ionization chamber 10, a second ionization chamber 20 and an injection control component 30; the first ionization chamber 10 is provided with a first injection port 10a; the second ionization chamber 20 is connected to the first ionization chamber 10, and the second ionization chamber 20 is provided with a second injection port 20a; the injection control component 30 is respectively connected to the first injection port 10a and the second injection port 20a and is suitable for introducing a sample b to be tested, and the injection control component 30 is used to control the sample b to be tested to enter the first ionization chamber 10 and / or the second ionization chamber 20.

[0028] In addition, the electron bombardment ionization source of the present invention can also be provided with more ionization chambers to achieve more ionization modes, thereby meeting the ionization requirements in more scenarios. In other words, the control of the introduction of the sample b to be tested by the injection control unit 30 of two or more ionization chambers connected in sequence belongs to the content covered by the technical solution of the present invention.

[0029] In this embodiment, the first ionization chamber 10 and the second ionization chamber 20 can both adopt a cross bombardment method. The electron bombardment ionization source also includes a first filament group 11 arranged in the first ionization chamber 10 and a second filament group 21 arranged in the second ionization chamber 20. The first filament group 11 and the second filament group 21 each include two filaments arranged opposite to each other, a total of four filaments. The energy of the electrons a entering the ionization chamber can be controlled by controlling the voltage of the filaments to meet the ionization requirements of different samples b to be tested. In order to improve the ionization effect of the cross bombardment, as shown in FIG. Figure 1 As shown, the first injection port 10a and the second injection port 20a can be respectively arranged in the middle of each ionization chamber, and the two filaments of each ionization chamber can be respectively arranged on both sides of the injection port.

[0030] In this embodiment, the sample injection control component 30 may be a sample switching valve or other devices that can effectively control the direction of the sample, which is not limited here.

[0031] It can be understood that the present invention improves the structure of the electron bombardment ionization source, determines whether the sample b to be tested flows to the first ionization chamber 10 or the second ionization chamber 20 through the injection control component 30, and sets two independently controllable ionization chambers to set different ionization modes, which greatly improves the adaptability of the electron bombardment ionization source to different samples. Suitable ionization methods can be used for different samples to meet different ionization requirements, thereby meeting the analysis requirements in different fields.

[0032] In some embodiments, reference Figures 2 to 5 , the volume of the first ionization chamber 10 can be set to be larger than the volume of the second ionization chamber 20. Its main purpose is: In some cases, such as Figure 2 As shown, the sample b to be tested is injected into the first ionization chamber 10 with a larger volume, and ionization is controlled to occur in the first ionization chamber 10. Since the first ionization chamber 10 is large in volume, it can carry more molecules of the test object, and can effectively ensure that the instrument is less contaminated in the case of high-concentration and high-throughput sampling, thereby ensuring the stability of the instrument.

[0033] In other cases, such as Figure 3 As shown, when the ionization concentration of the sample b to be tested is low and the injection volume is small, the sample b to be tested is injected into the second ionization chamber 20 with a smaller volume, and the ionization is controlled to occur in the second ionization chamber 20. Due to the small volume of the second ionization chamber 20, the sample b to be tested will not diffuse over a large area, and the molecules of the sample b to be tested are relatively concentrated, and the probability of collision between the molecules and the electron a is greater, which helps to improve the ionization efficiency; and the small volume of the ionization chamber can ensure that the generated fragment ions c have a more concentrated spatial distribution and energy distribution, so that the ion energy is more concentrated, which can ensure the high transmission efficiency of the ions, thereby improving the sensitivity of the instrument.

[0034] In addition, in some other cases, such as Figure 4 As shown, the sample b to be tested is injected into the first ionization chamber 10 with a larger volume, and ionization occurs in the first ionization chamber 10 and the second ionization chamber 20. The ion source has a higher ionization efficiency. In the case of high-concentration and high-throughput sampling, it can not only ensure that the instrument is less contaminated, but also ensure a higher ionization efficiency, thereby improving the signal response of the instrument to high-concentration samples.

[0035] In order to further improve the ionization efficiency, the main reference Figure 1 and Figure 2 In one embodiment, the electron bombardment ionization source may further include an extraction component. The second ionization chamber 20 is provided with a sample outlet 20b. The extraction component is connected to the sample outlet 20b and is suitable for being connected to the mass analyzer. The extraction component is used to extract the fragment ions c generated by ionization; the extraction component includes an extraction lens 41, a focusing lens 42 and an ejection lens 43 arranged in sequence at intervals. The extraction lens 41 is used to extract the fragment ions c from the sample outlet 20b, the focusing lens 42 is used to bunch the fragment ions c, and the ejection lens 43 is used to extract the fragment ions c to the mass analyzer.

[0036] Further, refer to Figure 1 and Figure 2 The electron bombardment ionization source may further include a repelling electrode 12, which is disposed in the first ionization chamber 10 or constitutes a chamber wall on one side of the first ionization chamber 10, and is used to push the generated fragment ions c to the sample outlet 20b. This arrangement helps to further improve the ionization effect of the electron bombardment ionization source.

[0037] like Figure 1 and Figure 2 As shown, when the electron bombardment ionization source is working, the sample b to be tested first enters the sample switching valve, and the sample switching valve is switched to determine whether to introduce the sample into the first injection port 10a or the second injection port 20a, and the sample enters the first ionization chamber 10 or the second ionization chamber 20 through the injection port. Each ionization chamber adopts a double filament structure, which is symmetrically placed around the ionization chamber. One filament can be turned on each time it works, and the electrons a emitted by the filament enter the ionization chamber through acceleration to form a high-energy electron beam (generally the acceleration voltage is 70V, so the energy of the high-energy electron beam is generally 70eV). The high-energy electron beam collides with the molecules of the sample b to be tested that enter the ionization chamber, so that the molecules of the sample b to be tested are ionized to generate fragment ions c. The repeller electrode 12 applies a positive voltage to push the generated fragment ions c into the rear end, and the extraction lens 41, the focusing lens 42, and the ejection lens 43 apply a negative voltage to extract the fragment ions c out of the ionization chamber and bunch the fragment ion c beam. The fragment ions c finally enter the mass analyzer of the next stage through the extraction lens 41, the focusing lens 42, and the ejection lens 43.

[0038] In some embodiments, Figures 2 to 5 As shown, the electron bombardment ionization source proposed in the present invention has at least four working modes: high flux mode, high sensitivity mode, secondary ionization mode and qualitative mode. These four working modes correspond to the following four groups of control methods: 1) When using high-throughput mode, mainly refer to Figure 2 The sample injection control component 30 controls the sample b to be tested to be introduced into the first ionization chamber 10 , and the first ionization chamber 10 works so that the sample b to be tested collides with the electron a in the first ionization chamber 10 .

[0039] In the high-throughput mode, the sample b to be tested is introduced into the first ionization chamber 10, and the filament of the first ionization chamber 10 is turned on. Electrons a collide with molecules of the sample b to be tested in the first ionization chamber 10 to form fragment ions c. At this time, the first ionization chamber 10 applies a zero potential voltage, and the second ionization chamber 20 applies a negative voltage. For the first ionization chamber 10, the second ionization chamber 20 plays a role similar to the above-mentioned extraction lens 41, and can introduce the fragment ions c into the second ionization chamber 20, and then into the extraction lens 41, the focusing lens 42, the ejection lens 43, and finally enter the next-stage mass analyzer.

[0040] It can be understood that in this mode, the sample b to be tested is injected into the first ionization chamber 10 with a larger volume, and ionization occurs in the first ionization chamber 10. Since the first ionization chamber 10 has a large volume, it can carry more molecules of the test object, and can ensure that the instrument is less contaminated under the condition of high concentration and high throughput injection, thereby ensuring the stability of the instrument.

[0041] 2) When using high sensitivity mode, mainly refer to Figure 3 The sample injection control unit 30 controls the sample b to be tested to be introduced into the second ionization chamber 20 , and the second ionization chamber 20 starts ionization work so that the sample b to be tested collides with the electron a in the second ionization chamber 20 .

[0042] In the high-sensitivity mode, the sample b to be tested is introduced into the second ionization chamber 20, and the filament of the second ionization chamber 20 is turned on. Electrons a collide with molecules of the sample b to be tested in the second ionization chamber 20 to form fragment ions c. At this time, a positive voltage is applied to the first ionization chamber 10, and a zero potential voltage is applied to the second ionization chamber 20. For the second ionization chamber 20, the first ionization chamber 10 plays a role similar to the repelling electrode 12, which can push the fragment ions c to the extraction lens 41, the focusing lens 42, and the ejection lens 43, and finally enter the next-stage mass analyzer.

[0043] It can be understood that in this mode, the sample b to be tested is injected into the second ionization chamber 20 with a smaller volume, and ionization occurs in the second ionization chamber 20. Due to the small volume of the second ionization chamber 20, the sample b to be tested will not diffuse over a large area, and the sample molecules are relatively concentrated, and the probability of collision with the electron a is greater, which helps to improve the ionization efficiency; and the small volume of the ionization chamber can ensure that the generated fragment ions c have a more concentrated spatial distribution and energy distribution, so that the ion energy is more concentrated, ensuring high ion transmission efficiency, thereby improving the sensitivity of the instrument. This mode is suitable for samples with low ionization concentration and small injection volume.

[0044] 3) When using the secondary ionization mode, refer to Figure 4 The sample injection control unit 30 controls the sample b to be tested to be introduced into the first ionization chamber 10 , and the first ionization chamber 10 and the second ionization chamber 20 start ionization work at the same time, so that the sample b to be tested collides with the electron a in the first ionization chamber 10 and the second ionization chamber 20 successively.

[0045] In the secondary ionization mode, the sample b to be tested is introduced into the first ionization chamber 10, and the filaments of the first ionization chamber 10 and the second ionization chamber 20 are turned on at the same time. Electrons a collide with molecules of the sample b to be tested in the first ionization chamber 10 to form fragment ions c. At this time, the first ionization chamber 10 applies a zero potential voltage, and the second ionization chamber 20 applies a smaller negative voltage. The fragment ions c enter the second ionization chamber 20 from the first ionization chamber 10, and a small amount of unionized molecules will be entrained into the second ionization chamber 20. The high-energy electrons a in the second ionization chamber 20 collide with these unionized molecules to form secondary ionization, so that the sample is ionized more fully. After the secondary ionization, the fragment ions c pass through the extraction lens 41, the focusing lens 42, and the ejection lens 43, and finally enter the mass analyzer of the next level.

[0046] It can be understood that in this mode, the sample b to be tested is injected into the first ionization chamber 10 with a larger volume, and ionization occurs in the first ionization chamber 10 and the second ionization chamber 20. This mode has a higher ionization efficiency than the high-throughput mode. In the case of high-concentration and high-throughput injection, it can ensure that the instrument is less contaminated and has a higher ionization efficiency, significantly improving the signal response of the instrument to high-concentration samples.

[0047] 4) When using the qualitative model, the main reference Figure 5, the sample b to be tested is a mixed sample, the sample injection control unit 30 controls the sample b to be tested to be introduced into the first ionization chamber 10, the first ionization chamber 10 turns on the soft ionization mode and controls the electron a energy emitted by the filament to gradually increase, and the second ionization chamber 20 turns on the hard ionization mode, so that the substance of the sample b to be tested is gradually soft-ionized to form molecular ions, and then enters the second ionization chamber 20 for hard ionization to generate fragment ions c. Among them, the electron a energy of the first ionization chamber 10 can be set to 7eV~20eV, and scanned from 7eV to 20eV, with a scanning step of 0.1eV, and the electron a energy of the second ionization chamber 20 can be set to 70eV.

[0048] In the qualitative mode, a sample b to be tested is introduced into the first ionization chamber 10, and the sample b to be tested is a mixed sample including a first substance b1 and a second substance b2. The filament of the first ionization chamber 10 and the filament of the second ionization chamber 20 are turned on at the same time, wherein the filament of the first ionization chamber 10 adopts a soft ionization mode, that is, the energy of the electron beam generated by the filament of the first ionization chamber 10 is set to 7eV~20eV (the ionization energy of general gas molecules is 7eV~20eV, that is, only one electron a is lost to generate the ionization energy of molecular ions), and the energy of the electron beam emitted by the filament of the second ionization chamber 20 is set to the conventional 70eV. The energy of the electron beam generated by the filament of the first ionization chamber 10 is scanned from 7eV to 20eV, and the scanning step is 0.1eV. When the energy of the electron a in the first ionization chamber 10 is just higher than the ionization energy of the first substance b1, the molecules of the substance are softly ionized. At this time, the molecules of the substance only lose one electron a to form the molecular ion c1 of the first substance. The first ionization chamber 10 applies a zero potential voltage, and the second ionization chamber 20 applies a smaller negative voltage. The molecular ion c1 of the first substance enters the second ionization chamber 20 under the action of the electric field, collides with the high-energy electron beam (70eV energy) in the second ionization chamber 20, and generates fragment ions c of the substance. The fragment ions c enter the next-stage mass analyzer through the extraction lens 41, the focusing lens 42, and the ejection lens 43 for qualitative analysis.

[0049] As the scan proceeds, the energy of the electron a in the first ionization chamber 10 continues to increase step by step. When its energy is just higher than the ionization energy of the second substance b2, the molecules of the first substance b1 and the molecules of the second substance b2 are softly ionized to form mixed molecular ions, namely, the molecular ions c1 of the first substance and the molecular ions of the second substance (not shown in the figure). The mixed molecular ions enter the second ionization chamber 20 and collide with the high-energy electron beam to generate mixed fragment ions c2 of the first substance b1 and the second substance b2. The mixed fragment ions c2 enter the mass analyzer through the extraction component for analysis to generate a mass spectrum.

[0050] It is understandable that, when the first substance b1 is known, the second substance b2 can be more accurately characterized. In this mode, various substances in the mixed sample can be analyzed one by one, eliminating the influence of spectral peak overlap when injecting samples simultaneously, and ensuring that the instrument has a higher qualitative ability.

[0051] In this embodiment, the high-throughput mode is to introduce the sample b to be tested into the first ionization chamber 10 for one ionization, and the high-sensitivity mode is to introduce the sample into the second ionization chamber 20 for one ionization. Since the first ionization chamber 10 is large in volume, the ion source is not easily contaminated in the high-throughput mode, which is suitable for high-concentration and high-throughput injection. Since the second ionization chamber 20 is small in volume, the ion source ionization efficiency will be higher in the high-sensitivity mode, which is suitable for samples with lower concentrations and smaller injection volumes.

[0052] In the secondary ionization mode, the filaments of the two ionization chambers both emit electrons a with an energy of 70 eV. The sample b to be tested cross-collides with the electron a in the first ionization chamber 10 for ionization, and then is introduced into the second ionization chamber 20. The electron beam of the second ionization chamber 20 cross-collides with the sample molecules again for deep ionization. Through two cross-collision ionizations, the sample can be ionized more fully, and the instrument can have a lower detection limit, which is suitable for analysis of trace samples.

[0053] In the qualitative mode, the first ionization chamber 10 adopts the soft ionization mode, and the electron beam energy is scanned from 7eV to 20eV, with a scanning step of 0.1eV, and the second ionization chamber 20 adopts a conventional 70eV electron beam. The mixed sample enters the first ionization chamber 10, and the electron a energy of the first ionization chamber 10 gradually increases. When it is just higher than the first ionization energy of a certain substance, the substance is softly ionized, and the generated molecular ions enter the second ionization chamber 20. The second ionization chamber 20 uses 70eV electrons to bombard the molecular ions to generate fragment ion peaks, and the mass spectrometer then performs qualitative analysis on the fragment ion peaks. By controlling the energy of the first ionization chamber 10, it can be ensured that the substance molecules in the mixed sample are softly ionized one by one and enter the second ionization chamber 20 one by one, thereby ensuring the accuracy of the qualitative analysis.

[0054] For the qualitative mode, a specific implementation example is used as an example to introduce it in detail: In a specific application scenario, the mixed sample contains four substances: oxygen, carbon dioxide, nitrogen, and carbon monoxide (in fact, the specific components of the mixed sample are unknown to the experimenter before the experiment). Under 70eV ionization, each substance has a standard spectrum library. Under low ionization energy, molecules can only be ionized into molecular ions. For example, carbon dioxide is only ionized into a mass spectrum peak of m / z=44, oxygen is only ionized into a mass spectrum peak of m / z=32, nitrogen is only ionized into a mass spectrum peak of m / z=28, and carbon monoxide is only ionized into a mass spectrum peak of m / z=28. If the mixture enters the standard ionization source, the standard ionization source uses 70eV electrons a for bombardment ionization, and the mass spectrum peaks generated by the four substances are superimposed on each other, making it difficult to resolve (for example, carbon dioxide, nitrogen, and carbon monoxide all have a mass spectrum peak at m / z=28. In the standard ionization source, the spectrum peaks are superimposed here, making it difficult to distinguish the types of substances in the mixture). The mixture is passed into the first ionization chamber 10 of the electron bombardment ionization source of the present invention, and the first ionization chamber 10 is scanned from 7eV to 20eV, and the scanning step is 0.1eV. It is known that the first ionization energy of each substance is different, for example, the first ionization energy of oxygen is 12.2eV, the first ionization energy of carbon dioxide is 13.8eV, the first ionization energy of carbon monoxide is 14.0eV, and the first ionization energy of nitrogen is 15.58eV. When the energy of the first ionization chamber 10 reaches 12.2eV, oxygen is softly ionized to generate molecular ions, and the molecular ions enter the second ionization chamber 20 under the action of the electric field and collide with the electron a of 70eV to generate fragment ions c, which are detected by the mass analyzer at the rear end, and analyzed and compared with the spectrum library to learn that the substance is oxygen. When the energy of the first ionization chamber 10 continues to increase to 13.8 eV, oxygen and carbon dioxide are softly ionized to generate molecular ions. The molecular ions enter the second ionization chamber 20 under the action of the electric field and collide with the 70 eV electron a to generate fragment ions c. The fragment ions c are detected by the mass analyzer at the back end. The spectrum at this time is the superimposed spectrum of oxygen and carbon dioxide. It is known that one substance is oxygen. The superimposed spectrum is subtracted from the standard spectrum of oxygen to obtain the spectrum of carbon dioxide. After analysis and comparison with the standard spectrum library, it is known that the second substance b2 is carbon dioxide. When the energy of the first ionization chamber 10 continues to increase to 14.0eV, oxygen, carbon dioxide, and carbon monoxide are softly ionized to generate molecular ions. Under the action of the electric field, the molecular ions enter the second ionization chamber 20 and collide with the 70eV electron a to generate fragment ions c. The fragment ions c are detected by the mass analyzer at the back end. The spectrum at this time is the superposition spectrum of oxygen, carbon dioxide, and carbon monoxide. At this time, it is known that the two substances are oxygen and carbon dioxide. The superimposed spectrum is subtracted from the standard spectrum of oxygen and carbon dioxide to obtain the spectrum of carbon monoxide. After analysis and comparison with the spectrum library, it is known that the third substance is carbon monoxide. By analogy, the fourth substance can be analyzed and found to be nitrogen.It can be seen that through the above method, it is possible to perform qualitative analysis on mixed samples containing multiple substances, greatly enhancing the qualitative analysis capability of the instrument.

[0055] In summary, the electron bombardment ionization source of the present invention adopts a dual ionization chamber and a four-filament structure, each ionization chamber can perform electron bombardment ionization independently, and each ionization chamber can adjust the ionization energy independently. In the present invention, the volumes of the two ionization chambers are different, the first ionization chamber 10 is larger in volume, and the second ionization chamber 20 is smaller in volume, and the present invention introduces a sample injection control component 30, which can control the sample to enter any ionization chamber. According to the injection volume and sample type, etc., a suitable ionization chamber can be selected in a targeted manner. For example, when the sample concentration is large, an ionization chamber with a larger volume can be selected, and the sample is not easily adsorbed on the inner wall of the ionization chamber, which can ensure the anti-pollution ability of the ionization chamber. The electron bombardment ionization source has four ionization modes: high-throughput mode, high-sensitivity mode, secondary ionization mode and qualitative mode. Different mass spectrometry data can be obtained by adopting different working modes, and targeted analysis can be performed on the sample b to be tested. For example, in the case of the secondary ionization mode, the instrument can have a lower detection limit, and can detect samples with lower concentrations. In the qualitative mode, the qualitative ability of the instrument can be enhanced. Among them, it should be particularly emphasized that in the qualitative mode, the first ionization chamber 10 adopts a soft ionization method, and gradually ionizes the substances of the sample b to be tested by gradually scanning the energy of the electron a, and gradually enters the second ionization chamber 20. The second ionization chamber 20 adopts a hard ionization method, and the substances to be tested entering the second ionization chamber 20 are subjected to hard ionization analysis to ensure the accuracy of the qualitative analysis. The present invention expands the application scenarios of the electron bombardment ionization source, can ensure that the instrument is not contaminated when high-concentration and high-throughput sampling is carried out, can ensure high ionization efficiency and high sensitivity of the instrument when low-concentration and small-volume sampling is carried out, and can ensure high qualitative ability of the instrument when complex sampling is carried out, thereby improving the versatility of the instrument and being able to meet the analysis needs of different fields.

[0056] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An electron bombardment ionization source, characterized in that: At least: A first ionization chamber is provided with a first injection port; a second ionization chamber, connected to the first ionization chamber, wherein the second ionization chamber is provided with a second injection port; as well as The sample injection control component is connected to the first sample injection port and the second sample injection port respectively and is suitable for introducing the sample to be tested. The sample injection control component is used to control the sample to be tested to enter the first ionization chamber and / or the second ionization chamber.

2. The electron bombardment ionization source according to claim 1, characterized in that: The sample injection control component is a sample switching valve, and the sample switching valve is used to control the flow direction of the sample to be tested; and / or The volume of the first ionization chamber is greater than the volume of the second ionization chamber.

3. The electron bombardment ionization source according to claim 1, characterized in that: The electron bombardment ionization source further includes a first filament group arranged in the first ionization chamber and a second filament group arranged in the second ionization chamber. The first filament group and the second filament group both include two filaments arranged opposite to each other.

4. The electron bombardment ionization source according to claim 1, characterized in that: The electron bombardment ionization source also includes an extraction component, the second ionization chamber is provided with a sample outlet, the extraction component is connected to the sample outlet and is suitable for being connected to a mass analyzer, and the extraction component is used to extract the fragment ions generated by ionization; the extraction component includes an extraction lens, a focusing lens and an ejection lens which are sequentially arranged at intervals, the extraction lens is used to extract the fragment ions from the sample outlet, the focusing lens is used to bunch the fragment ions, and the ejection lens is used to extract the fragment ions to the mass analyzer; and / or The electron bombardment ionization source further includes a repeller electrode, which is disposed in the first ionization chamber or constitutes a chamber wall on one side of the first ionization chamber, and is used to push the generated fragment ions toward the sample outlet.

5. The electron bombardment ionization source according to any one of claims 1 to 4, characterized in that: The electron bombardment ionization source has at least four working modes: high flux mode, high sensitivity mode, secondary ionization mode and qualitative mode; When the high-throughput mode is adopted, the sample injection control component controls the sample to be tested to be introduced into the first ionization chamber, and the first ionization chamber works so that the sample to be tested collides with electrons in the first ionization chamber; When the high-sensitivity mode is adopted, the sample injection control component controls the sample to be tested to be introduced into the second ionization chamber, and the second ionization chamber starts ionization work, so that the sample to be tested collides with electrons in the second ionization chamber; When the secondary ionization mode is adopted, the sample injection control component controls the sample to be tested to be introduced into the first ionization chamber, and the first ionization chamber and the second ionization chamber start ionization work at the same time, so that the sample to be tested collides in the first ionization chamber and the second ionization chamber successively; When the qualitative mode is adopted, the sample to be tested is a mixed sample, the injection control component controls the sample to be tested to be introduced into the first ionization chamber, the first ionization chamber starts the soft ionization mode and the electron energy gradually increases, and the second ionization chamber starts the hard ionization mode, so that the substances in the sample to be tested are gradually soft-ionized to form molecular ions, and then enter the second ionization chamber for hard ionization to generate fragment ions.

6. The electron bombardment ionization source according to claim 5, characterized in that: When the qualitative mode is adopted, the electron energy of the first ionization chamber is 7eV~20eV, and is scanned from 7eV to 20eV with a scanning step of 0.1eV. The electron energy of the second ionization chamber is 70eV.

7. The electron bombardment ionization source according to claim 5, characterized in that: When the high-throughput mode is adopted, a zero potential voltage is applied to the first ionization chamber, and a negative voltage is applied to the second ionization chamber, so as to introduce fragment ions into the second ionization chamber.

8. The electron bombardment ionization source according to claim 5, characterized in that: When the high-sensitivity mode is adopted, a positive voltage is applied to the first ionization chamber, and a zero potential voltage is applied to the second ionization chamber, so as to push the fragment ions into the second ionization chamber.

9. The electron bombardment ionization source according to claim 5, characterized in that: When the secondary ionization mode is adopted, a zero potential voltage is applied to the first ionization chamber, and a negative voltage is applied to the second ionization chamber, so that fragment ions enter from the first ionization chamber into the second ionization chamber.

10. The electron bombardment ionization source according to claim 5, characterized in that: When the qualitative mode is adopted, a zero potential voltage is applied to the first ionization chamber, and a negative voltage is applied to the second ionization chamber, so as to introduce molecular ions into the second ionization chamber.

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