Atmospheric pressure switchable laser ablation / electrospray ion source mass spectrometer and methods of use thereof

Abstract

This invention relates to a switchable laser ablation / electrospray ion source mass spectrometer device operating at atmospheric pressure and its method of use. This invention, through a switchable ion source, can efficiently and conveniently achieve diversification of ion generation types, and its structure is simple, allowing for flexible and convenient disassembly and switching. When studying complex molecular ion reactions, the switchable ion source can be applied to both solid and liquid samples. Different ion sources can be selected according to the sample type: a laser ablation ion source for solid samples and an electrospray ion source for liquid samples.

Description

Technical Field

[0001] This invention belongs to the field of mass spectrometry analysis, specifically relating to a mass spectrometer that can switch between laser ablation or electrospray ionization sources under atmospheric pressure and its usage method. Background Technology

[0002] The study of gas-phase ion structure and reactivity is a cutting-edge research area in chemical science. Clusters formed by a finite number of atoms are an important model for simulating catalytically active centers. Studying the reactions of gas-phase clusters with small molecules provides an effective way to understand the microscopic mechanisms of molecular activation and transformation. Many molecular ion reaction processes require mass spectrometry for study. The efficient and stable generation of target ions is a prerequisite for gas-phase ion research. For molecular ion reactions, the most commonly used sources are currently laser ablation ion sources and electrospray ion sources.

[0003] Laser ablation ion sources can stably convert solid samples into gaseous ions, control the synthesis of specific ion ratios, or directly characterize solid samples. The basic process involves a pulsed laser beam bombarding a solid sample target. The resulting plasma collides with a carrier gas or a dopant gas containing a certain proportion ejected from a pulse valve, cools, and forms target ions. Currently, this type of ion source is installed in a high vacuum, requiring pump shutdown for sample replacement, which is very cumbersome. Atmospheric pressure open-type laser ablation ion sources are currently unavailable.

[0004] Electrospray ionization sources can convert charged ions in a solution into gaseous ions under atmospheric pressure via an electrospray process. This method was first proposed by Fenn. The basic process is as follows: the solution of the analyte under normal pressure passes through a capillary with a high voltage. Under the action of a high electric field of several thousand volts, the liquid sample is sprayed into charged microdroplets due to the electric field. Subsequently, the solvent continuously evaporates and undergoes Coulomb explosion, thereby continuously reducing the volume and eventually forming gaseous ions that are completely free of solvent molecules.

[0005] Ions generated under atmospheric pressure, upon entering the primary differential section, experience jet expansion due to the rapid drop in vacuum to several Torr, resulting in a larger ion beam radius. Furthermore, frequent collisions between neutral gas molecules and the analyte ions force them into random and complex migration and diffusion, further expanding the ion beam radius. This leads to significant transmission losses and a substantial reduction in instrument sensitivity. Therefore, achieving efficient ion transport remains a challenge for atmospheric pressure ionization mass spectrometry. Ion funnels can significantly improve ion transport efficiency. This method, first proposed by Shaffer, typically consists of a series of concentric ring electrodes. Ions are focused by applying radio frequency and DC voltages to these ring electrodes.

[0006] Currently, conventional ion sources used for molecular ion reactions have limited functionality, and the synthesis of specific target ions is cumbersome. Due to limitations in sample types and the difficulty in sample replacement, it is impossible to switch between laser ablation ion sources and electrospray ion sources under atmospheric pressure, or to easily replace samples. Different mass spectrometers are often required, which is not only costly but also inconvenient to operate. Summary of the Invention

[0007] To address the problems existing in the prior art, one objective of this invention is to provide a switchable laser ablation / electrospray ion source mass spectrometer device operating at atmospheric pressure, thereby solving the problem that the prior art cannot achieve the switching between laser ablation ion sources and electrospray ion sources. Through the switchable ion source, convenient sample replacement and targeted synthesis of specific target ions using liquid or solid samples are achieved, thus enabling efficient and comprehensive research on molecular ion reactions.

[0008] The atmospheric pressure switchable laser ablation / electrospray ionization source mass spectrometer device according to the present invention is shown in the figure. Figure 1 It includes: an atmospheric pressure laser ablation ion source section, an electrospray ion source section, and cavity 8; wherein:

[0009] The atmospheric pressure laser ablation ion source includes: an ion source block 1 of arbitrary shape, a laser 2, a target 3, a carrier gas 4, and a fast flow tube 5; the ion source block 1 has an inlet channel (typically 0.1-5mm in diameter), through which the laser emitted by the laser 2 bombards the target 3; the carrier gas channel (typically 0.1-5mm in inner diameter) is perpendicular to and connected to the inlet channel; the target 3 is located next to the ion source block 1, driven by a motor and continuously rotated, its position being perpendicular and directly facing the inlet channel; the carrier gas 4 is ejected by a pulse valve into the carrier gas channel and carries gaseous ions; the outlet of the carrier gas channel is connected to the fast flow tube 5, and a DC voltage within ±500V is applied to the fast flow tube 5.

[0010] The atmospheric pressure laser ablation ion source and sample target are exposed to atmospheric pressure environment and can be switched at any time.

[0011] The fast-flow tube 5 can be a cylinder, cuboid, or other geometric shape with a length of about 10-200 mm and an inner diameter of 0.1-20 mm.

[0012] The electrospray ion source includes an electrospray probe 6 and an ion transmission tube 7, characterized by a cylinder with a length of 2-2000 mm and an inner diameter of 0.1-20 mm, and an outer cylinder, cuboid, or other geometric shapes; the electrospray probe 6 is equipped with a capillary nozzle (with an inner diameter of 0.1-5 mm) that applies a high voltage (±0.5 kV-±5 kV), and its position can be adjusted arbitrarily; the ion transmission tube 7 is located behind the nozzle of the electrospray probe 6, and a DC voltage within ±200 V is applied to the ion transmission tube 7.

[0013] The cavity 8 is the outer cavity of the entire mass spectrometer, including an adapter interface 9, a turning lens 10, an ion funnel 11, a quadrupole system 12, and an ion trap system. The adapter interface 9 is provided at the front of the cavity 8 and extends inward. The atmospheric pressure laser ablation ion source and the electrospray ion source are fixedly and sealed to the adapter interface 9 through an external extension plate provided on the fast flow tube 5 or the ion transmission tube 7.

[0014] The adapter interface 9 is characterized by being a cylinder, cuboid, or other geometric shape with a gradually decreasing inner diameter, and its rear inner diameter being 20-40% of the front inner diameter. The inner diameter of the adapter interface 9 is consistent with the outer diameter of the end of the fast flow tube 5 or the ion transmission tube 7, thereby ensuring that the fast flow tube 5 or the ion transmission tube 7 can be inserted into the adapter interface 9 and fixedly sealed.

[0015] The turning lens 10 is located after the adapter interface 9. It is a metal component with the inlet and outlet offset by 2-10 mm along the axis. Its internal shape is a non-linear cylinder with an inner diameter of 0.1-5 mm. A DC voltage within ±200V is applied to it. Neutral molecules are blocked by the turning lens 10, while the sample ions to be tested are guided through the turning lens 10 under the guidance of the electric field. Its main function is to prevent neutral molecules from contaminating the quadrupole and ion trap.

[0016] The electrodes of the ion funnel 11 are connected in sequence by multiple electrode plates, which can be separated by insulating sealing gaskets. Radio frequency voltages with equal amplitude and 180-degree phase difference are applied to adjacent electrode plates. The electrode plates are circular or quadrilateral or other polygonal shapes, and each electrode plate has a coaxial through hole at its center. The diameter of the through hole gradually decreases from the ion inlet end to the ion outlet end of the ion funnel 11 to form a funnel shape. The spacing between adjacent electrode plates can be between 0.5-10 mm. The number of electrode plates is determined according to the required length of the reaction tube, and is generally between 5 and 50 plates.

[0017] The quadrupole system 12 is located behind the ion funnel 11 and in front of the ion trap system, for allowing ions to pass through selectively or unselectively before entering the ion trap system.

[0018] The ion trap system includes: an ion trap front cover 13, an ion trap electrode 14, an ion trap rear cover 15, a buffer and reactive gas 16, and a detector 17; the ion trap front cover 13 has a small hole in the middle, which faces the quadrupole system 12, and ions enter the ion trap system through the small hole; the ion trap rear cover 15 has a small hole, and the buffer and reactive gas 16 is injected into the ion trap through the small hole of the ion trap rear cover 15 via a pulse valve or a flow meter. Beneficial effects

[0019] The device according to the present invention can switch between atmospheric pressure laser ablation ion source and electrospray ion source. After the original ion source is disassembled, the other ion source can be rematched using the adapter interface 9 and the cavity 8.

[0020] For solid samples, since it is necessary to synthesize some specific target ions, the proportion of solid components needs to be adjusted, so it is necessary to be able to easily change the sample. This device can easily and quickly change the sample; for liquid samples, this can be achieved by changing the solution.

[0021] The beneficial effects of this invention are that it allows the analysis of solid or liquid samples using a mass spectrometer, and through convenient sample replacement operations, it enables the targeted synthesis of specific target ions, thereby facilitating efficient molecular ion reaction research. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a switchable laser ablation / electrospray ion source mass spectrometer device under atmospheric pressure, according to an embodiment of the present invention.

[0024] Figure 2 This is a mass spectrum of the molecular ion reaction of a solid sample in an embodiment of the present invention. Figure 2 'a' represents the selected quality of IrC2H2 + , Figure 2 b and c of 2 are IrC2H2 + Mass spectra of the reaction with C2H2 and C2D2.

[0025] Figure 3 This is a mass spectrum of the molecular ion reaction of a liquid sample in an embodiment of the present invention. Figure 3 'a' represents the selected quality of VPO4. + , Figure 3 b is VPO4 + Mass spectrum of the reaction with C2H4.

[0026] Reference numerals in the attached figures: 1 is the ion source block, 2 is the laser, 3 is the target, 4 is the carrier gas, 5 is the fast flow tube, 6 is the electrospray probe, 7 is the ion transmission tube, 8 is the cavity, 9 is the adapter interface, 10 is the turning lens, 11 is the ion funnel, 12 is the quadrupole system, 13 is the ion trap front cover, 14 is the ion trap electrode, 15 is the ion trap rear cover, 16 is the buffer and reaction gas, and 17 is the detector. Detailed Implementation

[0027] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0028] To clarify the invention, parts irrelevant to the description have been omitted from the drawings, and throughout the specification, the same or similar parts are indicated by the same reference numerals.

[0029] Furthermore, for ease of explanation, the dimensions and thicknesses of each component shown in the accompanying drawings are arbitrarily illustrated; therefore, the invention is not necessarily limited to those shown in the drawings.

[0030] Throughout the specification, when it is said that an element is "connected" to another element, it includes not only "direct connection" but also "indirect connection" between other components. Furthermore, when it is said that an element "comprises" a part, it means that the element may further include other parts rather than exclude them, unless otherwise explicitly stated.

[0031] The following embodiments are merely examples illustrating implementations of the present invention and do not constitute any limitation on the present invention. Those skilled in the art will understand that modifications made without departing from the spirit and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following embodiments are commercially available products.

[0032] Example 1: Study on the molecular-ionic reaction of IrC2H2 cations

[0033] refer to Figure 1 For solid samples, when switching the laser ablation ion source, laser 2 is turned on to generate a laser beam, with the laser energy controlled at 15 mJ and the frequency at 4 Hz. The laser beam bombards the Ir metal target 3, which is driven by a motor and rotates continuously, through the laser channel of ion source block 1, generating Ir plasma. The plasma collides with the carrier gas 4 containing 1% C2H2 ejected by the pulse valve, and is further cooled by ultrasonic expansion, generating Ir plasma. + IrC2H2 + Other ions; the generated IrC2H2 + Ions enter the rapid flow tube 5 under the influence of pressure and voltage differences, and further pass through the turning lens 10 and ion funnel 11 to remove excess neutral substances. They are then fed into the ion trap system via the quadrupole system 12, where a single mass of IrC₂H₂ is selected by either the quadrupole system 12 or the ion trap system. + Then IrC2H2 + It reacts with the C2H2 gas introduced at 15°C to produce IrC4H4. + ( Figure 2 (a and b).

[0034] Example 2: Study on the molecular-ionic reaction of VPO4 cations

[0035] refer to Figure 1 For liquid samples, when switching to the electrospray ionization source, the peristaltic pump and high-voltage power supply are started. The liquid sample VOCl3 and triethyl phosphate acetonitrile solution enter the electrospray probe 6. After the mixed solution passes through the capillary nozzle with applied high voltage (3500V), it is transformed into charged microdroplets under the traction of the high-voltage electric field, and then transformed into VO2 through a desolvation process. + PO3 + VO + VO3 + and VPO4 + Gas-phase ions, including those from the ion funnel, pass through the adapter 9 into the turning lens 10 where excess neutral substances are removed. These ions then enter the ion funnel 11 and are focused. Multiple ions are fed into the ion trap via the quadrupole system 12, allowing selection of a single mass of VPO4 using either the quadrupole system 12 or the ion trap system. + After that, VPO4 + It reacts with the C2H4 reaction gas introduced through the rear cover 15 of the ion trap to generate VPO3. + and VPO4∙C2H4 + ( Figure 3 (a and b).

[0036] In this invention, the reaction gas is usually a neutral gas such as methane or ethylene, with a pressure of 0-1 atm, and the gas injection method is pulse injection (pulse width of 150us-10ms) or continuous injection.

[0037] In this invention, the voltage and timing of the laser power supply, carrier gas, and reaction gas pulse valves are controlled by a master controller.

[0038] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A switchable laser ablation / electrospray ionization source mass spectrometer device under atmospheric pressure, comprising: The atmospheric pressure laser ablation ion source section, the electrospray ion source section, and the cavity (8) are all exposed to the atmosphere and can be switched at any time. The atmospheric pressure laser ablation ion source includes: an ion source block (1) of arbitrary shape, a laser (2), a target (3), a carrier gas (4), and a fast flow tube (5); the ion source block (1) has an inlet channel with a diameter of 0.1-5 mm, through which the laser emitted by the laser (2) bombards the target (3); the carrier gas channel has an inner diameter of 0.1-5 mm, is perpendicular to and connected to the inlet channel; the target (3) is located next to the ion source block (1). Driven by a motor and continuously rotating, its position is vertical and directly facing the light inlet channel; the carrier gas (4) is ejected by a pulse valve into the carrier gas channel and carries gaseous ions; the outlet of the carrier gas channel is connected to the fast flow tube (5), and a DC voltage within ±500V is applied to the fast flow tube (5); the fast flow tube (5) is a cylinder or cuboid or other geometric shape with a length of 10-200mm and an inner diameter of 0.1-20mm; the atmospheric pressure laser ablation ion source is placed in an atmospheric pressure environment; The electrospray ion source includes an electrospray probe (6) and an ion transmission tube (7), characterized by a cylinder with a length of 2-2000 mm and an inner diameter of 0.1-20 mm, and an outer cylinder, cuboid, or other geometric shapes; the electrospray probe (6) is equipped with a capillary nozzle that applies a high voltage of ±0.5 kV to ±5 kV, with an inner diameter of 0.1-5 mm, and its position can be adjusted arbitrarily; the ion transmission tube (7) is located behind the electrospray probe (6), and a DC voltage within ±200 V is applied to the ion transmission tube (7).

2. The switchable laser ablation / electrospray ionization source mass spectrometer device under atmospheric pressure according to claim 1, characterized in that, The cavity (8) is the outer cavity of the entire mass spectrometer, including the adapter interface (9), the turning lens (10), the ion funnel (11), the quadrupole system (12) and the ion trap system, wherein the front of the cavity (8) is provided with the adapter interface (9) extending inward; the atmospheric pressure laser ablation ion source part and the electrospray ion source part are fixedly and sealed to the adapter interface (9) through the external extension plate provided on the fast flow tube (5) or the ion transmission tube (7).

3. The atmospheric pressure switchable laser ablation / electrospray ionization source mass spectrometer device according to claim 2, characterized in that, The adapter interface (9). Its features include a cylinder or cuboid and other geometric shapes with gradually decreasing inner diameter, and the inner diameter of its rear end is 20-40% of the inner diameter of its front end. The inner diameter of the adapter (9) is consistent with the outer diameter of the end of the fast flow tube (5) or the ion transport tube (7), thereby ensuring that the fast flow tube (5) or the ion transport tube (7) can be inserted into the adapter (9) and fixedly sealed.

4. The switchable laser ablation / electrospray ionization source mass spectrometer device under atmospheric pressure according to claim 2, characterized in that, The turning lens (10) is located after the adapter interface (9). It is a metal part with the inlet and outlet offset by 2-10 mm along the axis. The internal shape is a non-linear cylinder with an inner diameter of 0.1-5 mm. A DC voltage within ±200V is applied to it. Neutral molecules will be blocked by the turning lens (10), while the sample ions to be tested will pass through the turning lens (10) under the guidance of the electric field. Its main function is to prevent neutral molecules from contaminating the quadrupole system (12) and the ion trap system.

5. The switchable laser ablation / electrospray ionization source mass spectrometer device under atmospheric pressure according to claim 2, characterized in that, The electrodes of the ion funnel (11) are connected in sequence by multiple electrode plates, which are separated by insulating sealing gaskets. Radio frequency voltages with equal amplitude and 180-degree phase difference are applied to adjacent electrode plates. The electrode plates are circular or quadrilateral polygonal in shape and have a coaxial through hole at the center. The diameter of the through hole gradually decreases from the ion inlet end to the ion outlet end of the ion funnel (11) to form a funnel shape. The distance between adjacent electrodes can be between 0.5-10 mm. The number of electrode plates is determined according to the length of the reaction tube and is generally between 5 and 50.

6. The switchable laser ablation / electrospray ionization source mass spectrometer device under atmospheric pressure according to claim 2, characterized in that, The quadrupole system (12) is located behind the ion funnel (11) and in front of the ion trap system, for allowing ions to pass through selectively or unselectively and then enter the ion trap system.

7. The atmospheric pressure switchable laser ablation / electrospray ionization source mass spectrometer device according to claim 2, characterized in that, The ion trap system includes: an ion trap front cover (13), an ion trap electrode (14), an ion trap rear cover (15), a buffer and reactive gas (16), and a detector (17); the ion trap front cover (13) has a small hole in the middle, which faces the quadrupole system (12), and ions enter the ion trap system through the small hole; the ion trap rear cover (15) has a small hole, and the buffer and reactive gas (16) is injected into the ion trap through the small hole of the ion trap rear cover (15) via a pulse valve or a flow meter.

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