Ion-molecule reaction device and method for chemical ionization mass spectrometry detection

Abstract

The present invention discloses an ion-molecule reaction device and method for chemical ionization mass spectrometry detection, which belongs to the field of chemical ionization mass spectrometry detection technology, including a reaction body and a tapered end head, a cylindrical cavity is provided in the reaction body, and a tapered rectifier channel with a smooth transition with the cylindrical cavity is provided in the tapered end head; the reaction body is located at the inlet end of the cylindrical cavity and is correspondingly provided with a closed end cap, a tapered cavity corresponding to the cylindrical cavity is provided in the closed end cap, and an electrode for generating an electric field is provided in the circumferential direction of the inner wall of the tapered cavity; a gas-like joint is provided at the center of the top of the closed end cap, and an ion source joint connected to the tapered cavity is provided on one side of the top of the closed end cap. Reagent ions of the present invention can be focused on the axis of the cylindrical cavity and the tapered rectifier channel under the dual action of the electric field and flow field in the ion-molecule reaction device under atmospheric interface pressure, significantly improving the transmission efficiency of reagent ions, and then greatly improving the ion / molecule reaction efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical ionization mass spectrometry detection, and in particular to an ion-molecule reaction device and method for chemical ionization mass spectrometry detection. Background Art

[0002] Currently, atmospheric pressure interface mass spectrometers present significant challenges in detecting trace components in the atmosphere. For example, the detection of sulfuric acid in the atmosphere is a key example: gaseous sulfuric acid, a trace gas in the atmosphere, is highly acidic and hygroscopic, rapidly combining with alkaline gases in the atmosphere to form particles, making it the primary source of atmospheric particulate matter. The concentration of gaseous sulfuric acid can significantly affect the rate of particle formation and the number concentration of particles in the atmosphere, making its detection particularly important. However, existing studies have shown that atmospheric concentrations of sulfuric acid and other gases are extremely low, limiting detection methods and requiring extremely high instrumental sensitivity. Therefore, developing devices suitable for high-sensitivity detection is crucial for effectively controlling atmospheric particulate pollution and predicting its impact on climate change. Summary of the Invention

[0003] Technical problem to be solved: In response to the problems existing in the detection process of trace components in atmospheric pressure in the background technology, the present invention provides an ion-molecule reaction device and method for chemical ionization mass spectrometry detection, which can significantly improve the transmission efficiency of reaction reagent ions by using a combination of flow field and electric field under atmospheric interface pressure, thereby greatly improving the ion / molecule reaction efficiency, improving the sensitivity of mass spectrometry detection, and realizing high-precision detection of trace substances in the atmosphere.

[0004] Technical solution: The ion-molecule reaction device for chemical ionization mass spectrometry detection described in the present invention includes a reaction body and a tapered end correspondingly arranged at the tail end of the reaction body;

[0005] A cylindrical cavity is provided in the reaction body, and a conical rectifying channel which smoothly transitions with the cylindrical cavity is provided in the conical end head;

[0006] The reaction body is located at the inlet end of the cylindrical cavity and is provided with a closed end cover, wherein a conical cavity corresponding to the cylindrical cavity is provided inside the closed end cover, and an electrode for generating an electric field is provided in the circumferential direction of the inner wall of the conical cavity;

[0007] A gas sample connector is provided in the center of the top of the closed end cover, and the gas sample connector is coaxially arranged with the cylindrical cavity and the conical rectifying channel; an ion source connector connected to the conical cavity is provided on one side of the top of the closed end cover.

[0008] Preferably, a flange ring is formed on the outer circumference of the closed end cover, a threaded countersunk hole is circumferentially provided at the inlet end of the reaction body, the closed end cover is fixedly connected to the reaction body by a screw, and an O-ring is provided at the connection between the closed end cover and the reaction body.

[0009] Preferably, the cone top of the conical end is provided with a reaction outlet connected to the conical rectifying channel;

[0010] The pipe diameter ratio of the inlet end and the outlet end of the conical rectifier is (2.5~3.5):1.

[0011] Preferably, the length ratio of the cylindrical cavity to the conical rectifier is 1:(1~1.2).

[0012] Preferably, the reaction body and the closed end cap are made of polyetheretherketone (PEEK) material; and the tapered end is made of conductive metal.

[0013] The present invention discloses an ion-molecule reaction method for chemical ionization mass spectrometry detection, the method comprising:

[0014] The gas sample is injected into the conical cavity through the gas sample connector at a flow rate of 1-3 L / min under atmospheric pressure; the ion source is synchronously injected into the conical cavity through the ion source connector;

[0015] The gas sample and ion source generate reaction reagent ions under the action of the electric field generated by the electrode. The reaction reagent ions are gradually converged along the central axis of the reaction body under the synergistic action of the flow field formed by the cylindrical cavity and the conical rectifier channel and the electric field to form a charged ion beam to be measured and output from the reaction outlet.

[0016] Preferably, the reagent ions include H3O + 、NO + , O 2+ 、H3O + H2O、C2H6NH2 + positive ions and NO 2- 、NO 3- 、HSO 4- 、HNO3NO3 - of negative ions.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] The reaction reagent ions of the present invention can be focused on the axis of the cylindrical cavity and the conical rectifier channel under the dual action of the electric field and flow field in the ion-molecule reaction device under the atmospheric interface pressure, significantly improving the transmission efficiency of the reaction reagent ions, thereby greatly improving the ion / molecule reaction efficiency, improving the mass spectrometry detection sensitivity, and realizing high-precision detection of trace substances in the atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the three-dimensional structure of the ion-molecule reaction device of the present invention from a first perspective;

[0020] Figure 2 for Figure 1 Schematic diagram of the second-angle perspective of the ion-molecule reaction device;

[0021] Figure 3 for Figure 1 Axial structural cross-sectional view of the ion-molecule reaction device;

[0022] Figure 4 for Figure 1 Physical picture of the ion-molecule reaction device;

[0023] Figure 5 for Figure 1 3D diagram of laminar flow simulated by FLUENT in the ion-molecule reaction device;

[0024] Figure 6 for Figure 1 A top view of the electric field in the ion-molecule reaction device simulated using SIMION;

[0025] Figure 7 for Figure 1 3D diagram of the electric field in the ion-molecule reaction device simulated using SIMION;

[0026] Figure 8 is a positive ion detection mass spectrum generated during the detection process of the present invention;

[0027] Figure 9 It is a negative ion detection mass spectrum generated during the detection process of the present invention.

[0028] Figure numerals: 100, ion-molecule reaction device; 1, reaction body; 11, cylindrical cavity; 2, closed end cover; 21, conical cavity; 3, gas sample connector; 4, ion source connector; 5, conical end; 51, conical rectifier; 6, reaction outlet; 7, electrode; 8, O-ring. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following Figures 1 to 9 The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0030] Example 1: Figures 1 to 4 As shown, the present invention discloses an ion-molecule reaction device for chemical ionization mass spectrometry detection. The ion-molecule reaction device 100 includes a reaction body 1 and a tapered end 5 correspondingly arranged at the rear end of the reaction body 1. The reaction body 1 is made of polyetheretherketone (PEEK) material, and the tapered end 5 is made of conductive metal. The tapered end 5 meets the requirements of generating an electric field. A cylindrical cavity 11 is provided in the reaction body 1, and a tapered rectifier 51 that smoothly transitions with the cylindrical cavity 11 is provided in the tapered end 5. The top of the tapered end 5 is provided with a reaction outlet 6 that is connected to the tapered rectifier 51; wherein the diameter ratio of the inlet end and the outlet end of the tapered rectifier 51 is (2.5-3.5):1. The tapered rectifier 51 designed with this size ratio can carry out a large flow rate of injection under atmospheric pressure conditions, and through the interaction of the electric field and the flow field, the reaction reagent ions are focused, reducing the loss of gaseous reaction substances, and entering the various detection chambers at the rear end (not shown). The length ratio of the cylindrical cavity 11 to the conical rectifier 51 is 1: (1-1.2). The structure of the reaction body 1 and the conical end 5 is arranged such that the cylindrical cavity 11 and the conical rectifier 51 therein are funnel-shaped structures. Under the action of the flow field constrained by the funnel-shaped structure, the reaction reagent ions pass through the inner wall and the middle flow channel in a laminar flow form, thereby avoiding the wall loss caused by the turbulent flow state of the reaction reagent ions under low pressure conditions, and realizing the convergence of the charged ion beam to be measured. The flow state in the cavity of the ion-molecule reaction device adopts the laminar 3D flow state simulated by FLUENT. Figure 5 As shown in the figure, the ions to be measured and the reagent ions can fully react in the cylindrical cavity 11, thereby greatly improving the ion / molecule reaction efficiency. In addition, the ions to be measured are fully focused in the tapered rectifying channel 51 at the rear end through the dual effects of the flow field and the electric field, thereby improving the transmission efficiency of the reagent ions and enhancing the sensitivity of mass spectrometry detection.

[0031] The reaction body 1 is located at the inlet end of the cylindrical cavity 11 and is provided with a closed end cap 2, which is made of polyetheretherketone (PEEK) material. A conical cavity 21 corresponding to the cylindrical cavity 11 is provided in the closed end cap 2, and an electrode 7 for generating an electric field is provided in the circumferential direction of the inner wall of the conical cavity 21. The electrode 7 cooperates with the conical end head 5 to generate an electric field in the cylindrical cavity 11 and the conical rectifier 51, resulting in a gradually converging electric field formed in the conical rectifier 51, thereby pushing the reaction reagent ions to be further converged at the cavity axis, and then successively enter the subsequent ion guide tube and high vacuum ion flight time detection device, and are detected by the flight time mass spectrometer. The 3D and top views of the electric field in the cavity of the ion-molecule reaction device are simulated by SIMION. Figures 6 and 7 shown.

[0032] In a preferred embodiment, if Figures 1-3As shown, the outer circumference of the closed end cap 2 forms a flange ring, and the inlet end of the reaction body 1 is circumferentially provided with a threaded countersunk hole. The closed end cap 2 is fixedly connected to the reaction body 1 by a screw, and an O-ring 8 is provided at the connection between the closed end cap 2 and the reaction body 1. In this embodiment, the closed end cap 2 and the reaction body 1 are designed to be separated to facilitate the installation of the electrode 7; the tapered end 5 can adopt an integrated structure that is embedded with the reaction body 1.

[0033] In a preferred embodiment, if Figure 4 As shown, the closed end cap 2 and the reaction body 1 are integrally structured, and a threaded through-hole is also provided circumferentially on the closed end cap 2. The tapered end cap 5 is separated from the reaction body 1. That is, the closed end cap 2 is circumferentially fixedly connected to the reaction body 1 and the tapered end cap 5 by a screw disposed in the threaded through-hole. The specific connection method used for the reaction body 1, the closed end cap 2, and the tapered end cap 5 can be set according to needs and is not limited here.

[0034] A gas sample connector 3 is provided at the center of the top of the closed end cap 2. The gas sample connector 3 is coaxial with the cylindrical cavity 11 and the conical flow channel 51. The gas sample enters the conical cavity 21 at a relatively high flow rate of 1 to 3 L / min under atmospheric pressure through the gas sample connector 3. An ion source connector 4 is provided on one side of the top of the closed end cap 2 and is connected to the conical cavity 21. Ions enter the conical cavity 21 through the ion source connector 4.

[0035] Example 2: The present invention discloses an ion-molecule reaction method for chemical ionization mass spectrometry detection, the method comprising:

[0036] The gas sample is injected into the conical cavity 21 through the gas sample connector 3 at a flow rate of 1-3 L / min under atmospheric pressure; the ion source is synchronously injected into the conical cavity 21 through the ion source connector 4;

[0037] The gas sample and the ion source generate reaction reagent ions under the action of the electric field generated by the electrode 7. The reaction reagent ions are gradually converged along the central axis of the reaction body 1 under the synergistic action of the flow field formed by the cylindrical cavity 11 and the conical rectifying channel 51 and the electric field to form a charged ion beam to be measured and output from the reaction outlet 6.

[0038] Taking the detection of gaseous sulfuric acid in the air as an example, a sufficient amount of NO2 reagent gas (zero air as carrier gas) is introduced into the ion source connector 4 to completely convert the primary ions into more stable nitrate ions. Then the nitrate ions react completely with the gaseous sulfuric acid introduced into the gas sample connector 3 to form hydrogen sulfate ions (H2SO4+NO3 - (HNO3) n →HSO4 -+(n+1)HNO3), and then is converged into the conical rectifier channel 51, and is finally detected by the detector at the rear end. The ion-molecule reaction device 100 can greatly improve the ion / molecule reaction efficiency, improve the sensitivity of mass spectrometry detection, and achieve high-precision detection of trace substances in the atmosphere.

[0039] Reagent ions include H3O + 、NO + , O 2+ 、H3O + H2O、C2H6NH2 + positive ions and NO 2- 、NO 3- 、HSO 4- 、HNO3NO3 - Both positive and negative ions can be focused on the axis of the cylindrical cavity 11 and the conical rectifier 51 under the dual effects of the electric field and flow field in the ion-molecule reaction device 100, significantly improving the transmission efficiency of the reagent ions and thus greatly improving the ion / molecule reaction efficiency. Figure 8 It can be seen that hydrated hydrogen protons (H3O + ) The mass spectra are ranked from low to high in order: m / q19 (H3O + )、m / q30 (NO + )、m / q32 (O2 + )、m / q37 (H3O + H2O)、m / q46 (C2H6NH2 + );Depend on Figure 9 It can be seen that nitrate ions (NO3 - ) The mass spectra are as follows from low to high: m / q46 (NO2 - )、m / q62 (NO3 - )、m / q97 (HSO4 - )、m / q125 (HNO3NO3 - ), it can be seen that the ion-molecule reaction device 100 can produce stable reaction reagent ions.

[0040] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ion-molecule reaction device for chemical ionization mass spectrometry detection, characterized in that: The ion-molecule reaction device (100) comprises a reaction body (1) and a tapered end (5) correspondingly arranged at the rear end of the reaction body (1); A cylindrical cavity (11) is provided in the reaction body (1), and a conical rectifying channel (51) which smoothly transitions with the cylindrical cavity (11) is provided in the conical end (5); The reaction body (1) is provided with a closed end cap (2) at the inlet end of the cylindrical cavity (11), a conical cavity (21) corresponding to the cylindrical cavity (11) is provided inside the closed end cap (2), and an electrode (7) for generating an electric field is provided in the circumferential direction of the inner wall of the conical cavity (21); A gas sample connector (3) is provided at the center of the top end of the closed end cover (2), and the gas sample connector (3) is coaxially arranged with the cylindrical cavity (11) and the conical rectifying channel (51); an ion source connector (4) in communication with the conical cavity (21) is provided on one side of the top end of the closed end cover (2).

2. The ion-molecule reaction device for chemical ionization mass spectrometry detection according to claim 1, characterized in that: The closed end cover (2) forms a flange ring on its outer circumference, and a threaded countersunk hole is provided on the circumference of the inlet end of the reaction body (1). The closed end cover (2) is fixedly connected to the reaction body (1) through a screw, and an O-type sealing ring (8) is provided at the connection between the closed end cover (2) and the reaction body (1).

3. The ion-molecule reaction device for chemical ionization mass spectrometry detection according to claim 1, characterized in that: The cone top of the conical end (5) is provided with a reaction outlet (6) connected to the conical rectifying channel (51); The pipe diameter ratio between the inlet end and the outlet end of the conical rectifying channel (51) is (2.5-3.5):

1.

4. The ion-molecule reaction device for chemical ionization mass spectrometry detection according to claim 3, characterized in that: The length ratio of the cylindrical cavity (11) to the conical rectifying channel (51) is 1:(1-1.2).

5. The ion-molecule reaction device for chemical ionization mass spectrometry detection according to any one of claims 1 to 4, characterized in that: The reaction body (1) and the closed end cap (2) are made of polyetheretherketone (PEEK) material; and the tapered end (5) is made of conductive metal.

6. An ion-molecule reaction method for chemical ionization mass spectrometry detection, characterized in that: Using the ion-molecule reaction device (100) according to claim 5, the method comprises: The gas sample is injected into the conical cavity (21) through the gas sample connector (3) at a flow rate of 1 to 3 L / min under atmospheric pressure; the ion source is synchronously injected into the conical cavity (21) through the ion source connector (4); The gas sample and the ion source generate reaction reagent ions under the action of the electric field generated by the electrode (7). The reaction reagent ions gradually converge along the central axis of the reaction body (1) under the synergistic action of the flow field formed by the cylindrical cavity (11) and the conical rectifying channel (51) and the electric field to form a charged ion beam to be measured and output from the reaction outlet (6).

7. The ion-molecule reaction method for chemical ionization mass spectrometry detection according to claim 6, characterized in that: The reagent ions include H3O + 、NO + , O 2+ 、H3O + H2O、C2H6NH2 + positive ions and NO 2- 、NO 3- 、HSO 4- 、HNO3NO3 - of negative ions.

Images