Electrospray extraction photoionization combined ion source for atmospheric pressure interface mass spectrometry

Abstract

This invention discloses an electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, belonging to the field of mass spectrometry detection. It includes a sample transport and ionization mechanism, an extraction electrospray mechanism, and a vacuum ultraviolet light source mechanism. The extraction electrospray mechanism is fixedly connected to the sample transport and ionization mechanism, and the sample transport and ionization mechanism is fixedly connected to the vacuum ultraviolet light source mechanism. This invention utilizes the aforementioned electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, enabling efficient ionization of gaseous and particulate organic components of different polarities, volatility, and molecular weights in the air. Through a reasonable structural design, it can operate under atmospheric pressure conditions, achieving the purpose of coupling with atmospheric pressure interface mass spectrometry.

Description

Technical Field

[0001] This invention relates to the field of mass spectrometry detection, and in particular to an electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry. Background Technology

[0002] The ionization source is the core component of a mass spectrometer, used to convert neutral molecules into ions. It is the primary step in mass spectrometry analysis, affecting the sensitivity, analytical range, and stability of the entire mass spectrometer system. Electrospray extraction ionization (EESI) is an atmospheric pressure soft ionization technique derived from electrospray ionization (ESI), capable of simultaneously and directly detecting gaseous and particulate phase components. Unlike conventional ESI, which directly atomizes the sample solution to form sample ions, the ionization process in EESI first uses high-purity extraction reagents to form charged microdroplets through the ESI process. These primary spray droplets then collide with the sample gas or aerosol particles, partially or completely extracting the sample components. Subsequently, during the desolvation and volatilization of the electrospray droplets, a coulombic explosion occurs, generating sample ions. Simultaneously, some analytes in the aerosol are also extracted and desolvated into the gas phase. This ion source has the following advantages: it allows for direct sample injection and detection at atmospheric pressure, offering good flexibility; the selectivity of ionization can be improved by adding other reagents (such as NaI) to the spray solvent, resulting in a wide variety of ionizable substances; it performs soft ionization, producing almost no fragment ions; and it can ionize weakly volatile and even non-volatile macromolecular compounds, making it particularly suitable for polar and thermally unstable compounds. Therefore, it is currently widely used in research on exhaled metabolic components, real-time evolution of atmospheric aerosol composition, and explosive component analysis. However, EESI has a relatively weak ionization ability for weakly polar and volatile small molecule compounds.

[0003] Photoionization is a soft ionization technique primarily used to ionize gaseous organic compounds. During ionization, sample molecules absorb photons, causing substances with energies reaching or exceeding their own ionization energy to lose electrons and become ions. Photoionization mass spectrometry typically uses vacuum ultraviolet (VUV) photoionization of the analyte to excite krypton gas. The photon energy is approximately ~10 eV. Except for a few small organic molecules containing three or fewer carbon atoms with ionization energies higher than 10 eV, it is widely applicable to most polar and nonpolar organic compounds. Furthermore, it offers numerous other advantages, including high ionization efficiency, fewer product fragments, and simpler mass spectra.

[0004] It is evident that combining these two ionization technologies can not only achieve highly efficient ionization of organic compounds with different polarities, volatility, and molecular weights, but also enable simultaneous real-time online detection of organic components in the gas phase and aerosols. Electrospray extraction ionization typically operates at atmospheric pressure, while photoionization typically operates under vacuum. Therefore, how to combine these two ionization technologies to operate under atmospheric pressure is a key technical challenge that needs to be addressed. Utility Model Content

[0005] The purpose of this invention is to provide an electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, which enables efficient ionization of gaseous and particulate organic components of different polarities, volatility and molecular weights in the air. Through reasonable structural design, it can operate under atmospheric pressure conditions, thus achieving the purpose of being coupled with atmospheric pressure interface mass spectrometry.

[0006] To achieve the above objectives, this utility model provides an electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, including a sample transport and ionization mechanism, an extraction electrospray mechanism, and a vacuum ultraviolet light source mechanism. The extraction electrospray mechanism is fixedly connected to the sample transport and ionization mechanism, and the sample transport and ionization mechanism is fixedly connected to the vacuum ultraviolet light source mechanism.

[0007] Preferably, the sample transport and ionization mechanism includes a sample inlet pipe, an ionization chamber, an ion source shell, and a mass spectrometry interface. The sample inlet pipe is connected to the ionization chamber inlet by welding and sealing. The ionization chamber is located inside the ion source shell, and the ionization chamber outlet is connected to the mass spectrometry interface.

[0008] Preferably, the ionization chamber is a cylindrical structure made of stainless steel, and the sample inlet tube, the ionization chamber inlet, and the mass spectrometer interface are coaxial.

[0009] Preferably, the extraction electrospray mechanism includes an extraction reagent vial, an extraction reagent transfer tube, an extraction reagent spray needle, a spray needle fixing and locking connector, a spray needle position adjustment structure, and a high-voltage electrode. The high-voltage electrode is placed inside the extraction reagent vial. The extraction reagent vial is connected to the extraction reagent spray needle through the extraction reagent transfer tube. The extraction reagent spray needle is fixed and locked to the ion source shell through the spray needle fixing and locking connector. The spray needle position adjustment structure is connected to the extraction reagent spray needle.

[0010] Preferably, the extraction reagent nozzle is a metal capillary tube, and the extraction reagent nozzle is set at an acute angle to the sample inlet tube, with the angle being 30°~60°.

[0011] Preferably, the vacuum ultraviolet light source mechanism includes a dielectric gas inlet pipe, a dielectric gas outlet pipe, a quartz lamp tube, an RF power supply, an RF coil, a magnesium fluoride lens, a sealing ring, and a sealing cover. The dielectric gas inlet pipe is located on the wall of the quartz lamp tube, and the dielectric gas outlet pipe is located at the end of the quartz lamp tube. The RF coil is wound around the outer wall of the quartz lamp tube. One end of the RF coil is connected to the RF power supply, and the other end is grounded. The magnesium fluoride lens is sealed to the upper part of the ionization chamber through a coaxially mounted sealing ring, and a sealing cover is fixedly provided outside the sealing ring.

[0012] Preferably, the quartz lamp tube has a cylindrical structure, and the light emission direction of the magnesium fluoride lens is perpendicular to the direction of the sample inlet pipe, and also perpendicular to the plane where the extraction reagent transfer pipe and the extraction reagent nozzle are located.

[0013] Therefore, this invention employs the aforementioned electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, enabling efficient ionization of gaseous and particulate organic components of different polarities, volatility, and molecular weights in the air. Through a reasonable structural design, it can operate under atmospheric pressure conditions, achieving the goal of being coupled with atmospheric pressure interface mass spectrometry.

[0014] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0015] Figure 1 This is a right view of an embodiment of the electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry of this utility model;

[0016] Figure 2 This is a top view of an embodiment of the electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry of this utility model;

[0017] Figure 3 This is a front view of an embodiment of the electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry of this utility model.

[0018] Figure Labels

[0019] 1. Sample inlet tube; 2. Extraction reagent vial; 3. Extraction reagent transfer tube; 4. Extraction reagent nozzle; 5. Nozzle fixing and locking connector; 6. Nozzle position adjustment structure; 7. High voltage electrode; 8. Medium gas inlet tube; 9. Medium gas outlet tube; 10. Quartz lamp tube; 11. Radio frequency power supply; 12. Radio frequency coil; 13. Magnesium fluoride lens; 14. Sealing ring; 15. Sealing cap; 16. Ionization chamber; 17. Ion source shell; 18. Mass spectrometer interface. Detailed Implementation

[0020] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0021] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0022] Example

[0023] like Figures 1 to 3 As shown, this invention provides an electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, including a sample transport and ionization mechanism, an extraction electrospray mechanism, and a vacuum ultraviolet light source mechanism. The extraction electrospray mechanism is fixedly connected to the sample transport and ionization mechanism, and the sample transport and ionization mechanism is fixedly connected to the vacuum ultraviolet light source mechanism. The sample transport and ionization mechanism is used to transport the sample from the sample inlet tube 1 through the ionization chamber 16 to the mass spectrometer. The extraction electrospray mechanism is used to deliver a stable charged spray generated by the extraction reagent into the ionization chamber 16. The vacuum ultraviolet light source mechanism is used to generate stable and continuous vacuum ultraviolet light and deliver high-throughput photons into the ionization chamber 16.

[0024] The sample transport and ionization mechanism includes a sample inlet pipe 1, an ionization chamber 16, an ion source housing 17, and a mass spectrometry interface 18. The sample inlet pipe 1 is welded and sealed to the inlet of the ionization chamber 16 for stable transport of gaseous and aerosol samples. The ionization chamber 16 is located inside the ion source housing 17 and is used to generate analyte ions by electrospray extraction ionization or photoionization. The ion source housing 17 is used for supporting and loading the internal components of the ion source and for sealing the connection with the mass spectrometry system. The outlet of the ionization chamber 16 is connected to the mass spectrometry interface 18 to enable the mass spectrometer to recognize the ion signal and to provide the required electrode voltage and sampling protective gas to the ion source via the mass spectrometer.

[0025] The ionization chamber 16 is a cylindrical structure made of stainless steel. The sample inlet pipe 1, the inlet of the ionization chamber 16 and the mass spectrometer interface 18 are coaxial, which makes the sample delivery more stable.

[0026] The extraction electrospray mechanism includes an extraction reagent vial 2, an extraction reagent transfer tube 3, an extraction reagent spray needle 4, a spray needle fixing and locking connector 5, a spray needle position adjustment structure 6, and a high-voltage electrode 7. The high-voltage electrode 7 is placed inside the extraction reagent vial 2 and is used to provide high voltage to the extraction reagent, so that the sprayed droplets are charged. The extraction reagent vial 2 is used to hold the extraction reagent and is stably delivered to the extraction reagent transfer tube 3 by nitrogen pressurization. The extraction reagent vial 2 is connected to the extraction reagent spray needle 4 through the extraction reagent transfer tube 3, and is used to transfer the extraction reagent from the extraction reagent vial 2 to the extraction reagent spray needle 4. The extraction reagent spray needle 4 is fixed and locked to the ion source shell 17 through the spray needle fixing and locking connector 5, and is used to spray the extraction reagent in the form of atomized droplets, so that it can fully contact the sample. The spray needle position adjustment structure 6 is connected to the extraction reagent spray needle 4. The spray needle position adjustment structure 6 adopts the structure of the prior art and is used to adjust the position of the extraction reagent spray needle 4 in the ionization chamber 16 so that the spray droplets can fully extract the sample.

[0027] The extraction reagent nozzle 4 is a metal capillary tube, which is set at an acute angle to the sample inlet tube 1, with an angle of 30°~60°. This ensures that the extraction spray droplets are in full contact with the sample molecules, while reducing direct collisions and agglomeration of the droplets, making the droplets smaller and more evenly distributed. This makes it easier to form gaseous ions during the desolvation process, thereby improving the ionization efficiency of electrospray extraction ionization.

[0028] The vacuum ultraviolet light source mechanism includes a dielectric gas inlet pipe 8, a dielectric gas outlet pipe 9, a quartz lamp tube 10, a radio frequency power supply 11, a radio frequency coil 12, a magnesium fluoride lens 13, a sealing ring 14, and a sealing cover 15. The dielectric gas inlet pipe 8 is located on the wall of the quartz lamp tube 10, and the dielectric gas outlet pipe 9 is located at the end of the quartz lamp tube 10, used for continuously introducing and expelling krypton gas as the dielectric gas, respectively. The radio frequency coil 12 is wound around the outer wall of the quartz lamp tube 10, with one end connected to the radio frequency power supply 11 and the other end grounded. The magnesium fluoride lens 13 is sealed to the upper part of the ionization chamber 16 via a coaxially mounted sealing ring 14, and a sealing cover 15 is fixedly installed outside the sealing ring 14. Under the action of radio frequency, the dielectric gas generates luminescent plasma and releases heat. Due to thermal expansion and contraction, the dielectric gas undergoes frequent heat exchange and flow within the quartz lamp tube 10, thereby maintaining the purity of the dielectric gas within the quartz lamp tube 10 and achieving stable output of vacuum ultraviolet light.

[0029] The quartz lamp tube 10 has a cylindrical structure. The light emission direction of the magnesium fluoride lens 13 is perpendicular to the direction of the sample inlet tube 1 and perpendicular to the plane where the extraction reagent transfer tube 3 and the extraction reagent nozzle 4 are located, so that the sample components are in direct contact with high-throughput photons.

[0030] Working principle:

[0031] High voltage is supplied to the extraction reagent in the extraction reagent vial 2 by high voltage electrode 7. Nitrogen gas is used to pressurize the extraction reagent in the extraction reagent vial 2 and stably deliver it to the extraction reagent spray needle 4 through the extraction reagent delivery tube 3. The extraction reagent spray needle 4 sprays the extraction reagent in the form of charged atomized droplets. The position of the extraction reagent spray needle 4 in the ionization chamber 16 is adjusted by the spray needle position adjustment structure 6 so that the spray droplets can fully contact the sample, thereby fully extracting the sample.

[0032] Krypton gas is continuously introduced and discharged as the discharge medium gas through the medium gas inlet pipe 8 and the medium gas outlet pipe 9 on the tube wall and end of the quartz lamp tube 10. The radio frequency power supply 11 provides radio frequency power input to the radio frequency coil 12. The radio frequency coil 12 generates an induced magnetic field and an electric field inside the quartz lamp tube 10. Under the action of the induced electromagnetic field, the medium gas generates luminescent plasma and outputs high-flux vacuum ultraviolet light. The generated vacuum ultraviolet light enters the ionization cavity 16 through the magnesium fluoride lens 13.

[0033] The sample enters the ionization chamber 16 stably through the sample inlet tube 1. Charged droplets of extraction reagent sprayed by the extraction reagent nozzle 4 come into contact with and collide with the sample gas or aerosol particles. The sample components are partially or completely extracted by the droplets. Subsequently, during the electrospray droplet desolvation and volatilization process, a coulomb explosion occurs to generate sample ions, or sample ions are formed directly by single-photon ionization under the action of vacuum ultraviolet light.

[0034] The generated sample ions flow out of the ionization chamber 16 under the traction of the flow field, and then enter the mass spectrometry interface 18 for detection.

[0035] Therefore, this invention employs the aforementioned electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry, enabling efficient ionization of gaseous and particulate organic components of different polarities, volatility, and molecular weights in the air. Through a reasonable structural design, it can operate under atmospheric pressure conditions, achieving the goal of being coupled with atmospheric pressure interface mass spectrometry.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. An electrospray extraction / photoionization combined ion source for atmospheric pressure interface mass spectrometry, characterized in that: It includes a sample transport and ionization mechanism, an extraction electrospray mechanism, and a vacuum ultraviolet light source mechanism. The extraction electrospray mechanism is fixedly connected to the sample transport and ionization mechanism, and the sample transport and ionization mechanism is fixedly connected to the vacuum ultraviolet light source mechanism.

2. The electrospray extraction photoionization combined ion source for atmospheric pressure interface mass spectrometry of claim 1, wherein: The sample transport and ionization mechanism includes a sample inlet tube, an ionization chamber, an ion source shell, and a mass spectrometry interface. The sample inlet tube is connected to the ionization chamber inlet by welding and sealing. The ionization chamber is located inside the ion source shell, and the ionization chamber outlet is connected to the mass spectrometry interface.

3. The electrospray extraction photoionization combined ion source for atmospheric pressure interface mass spectrometry of claim 2, wherein: The ionization chamber is a cylindrical structure made of stainless steel, and the sample inlet tube, ionization chamber inlet and mass spectrometer interface are coaxial.

4. The electrospray extraction photoionization combined ion source for atmospheric pressure interface mass spectrometry of claim 2, wherein: The extraction electrospray mechanism includes an extraction reagent vial, an extraction reagent transfer tube, an extraction reagent spray needle, a spray needle fixing and locking connector, a spray needle position adjustment structure, and a high-voltage electrode. The high-voltage electrode is placed inside the extraction reagent vial. The extraction reagent vial is connected to the extraction reagent spray needle through the extraction reagent transfer tube. The extraction reagent spray needle is fixed and locked to the ion source shell through the spray needle fixing and locking connector. The spray needle position adjustment structure is connected to the extraction reagent spray needle.

5. The electrospray extraction photoionization combined ion source for atmospheric pressure interface mass spectrometry of claim 4, wherein: The extraction reagent nozzle is a metal capillary tube, and the extraction reagent nozzle is set at an acute angle to the sample inlet tube, with an angle of 30°~60°.

6. The electrospray extraction photoionization combined ion source for atmospheric pressure interface mass spectrometry of claim 4, wherein: The vacuum ultraviolet light source mechanism includes a dielectric gas inlet pipe, a dielectric gas outlet pipe, a quartz lamp tube, an RF power supply, an RF coil, a magnesium fluoride lens, a sealing ring, and a sealing cover. The dielectric gas inlet pipe is located on the wall of the quartz lamp tube, and the dielectric gas outlet pipe is located at the end of the quartz lamp tube. An RF coil is wound around the outer wall of the quartz lamp tube. One end of the RF coil is connected to the RF power supply, and the other end is grounded. The magnesium fluoride lens is sealed to the upper part of the ionization chamber through a coaxially mounted sealing ring, and a sealing cover is fixed outside the sealing ring.

7. The electrospray extraction / photoionization composite ion source for atmospheric pressure interface mass spectrometry according to claim 6, characterized in that: The quartz lamp tube has a cylindrical structure. The light emission direction of the magnesium fluoride lens is perpendicular to the direction of the sample inlet tube and also perpendicular to the plane of the extraction reagent transfer tube and the extraction reagent nozzle.

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