Mass spectrometer with double ionization sources

Abstract

The invention provides a double-ionization-source mass spectrometer. The double-ionization-source mass spectrometer comprises a proton transfer reaction ionization source, an electrospray ionization source and an online flow purging sampling system, the online flow purging sampling system is used for separating a liquid sample, volatile or semi-volatile organic compounds are introduced into the proton transfer reaction ionization source, and liquid is introduced into the electrospray ionization source; the electrospray ionization source is used for carrying out spray ionization on organic matters difficult to volatilize or strong in polarity in the liquid; and the proton transfer reaction ionization source is used for ionizing volatile and semi-volatile organic compounds and performing mass spectrometry, and performing mass spectrometry on non-volatile or strong-polarity organic compounds after spray ionization. According to the invention, the same mass spectrometer can simultaneously analyze volatile, semi-volatile, difficult-to-volatilize and strong-polarity organic matters in a liquid sample innovatively, and rapid, real-time and comprehensive online monitoring of liquid-phase organic pollutants is realized. The method can be applied to on-line rapid detection of organic matters in liquid-phase samples such as drinking water, surface water, biological fluid and liquid materials.

Description

Technical Field

[0001] This application belongs to the technical field of mass spectrometers, and more specifically, relates to a dual ionization source mass spectrometer. Background Art

[0002] The detection of organic compounds in liquid samples has always been the focus of attention in fields such as scientific research, environmental monitoring, and public health. Online and rapid detection of organic compounds in liquid samples helps to dynamically evaluate water quality safety and timely monitor industrial emissions.

[0003] Currently, in the research and application of detecting organic compounds in liquids, it still mainly relies on manual sampling combined with traditional laboratory instrument analysis. Traditional laboratory detection mainly focuses on chromatography techniques and chromatography-mass spectrometry coupling techniques, such as Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS), which have been proven to have good accuracy and reliability in the field of monitoring and early warning of organic compounds in liquid samples. The off-line chromatography-mass spectrometry coupling technique has certain limitations: First, due to the limitation of the chromatography separation principle, these methods often have certain selectivity during analysis. Different types of chromatographic columns need to be selected according to the properties of the analytes, and it is difficult to achieve a relatively comprehensive full-spectrum analysis in one detection. Second, the detection methods of chromatography-mass spectrometry often need to be combined with off-line enrichment methods such as solid-phase microextraction to improve the detection sensitivity. This process will cause the loss of some organic compounds, and the detection results are greatly affected by sample pretreatment. Finally, the complex sample pretreatment, enrichment, and chromatography separation processes of these methods make the full-process analysis time of a single sample at least dozens of minutes or even several hours or more, resulting in disadvantages such as complex and cumbersome analysis processes, time-consuming operations, and inability to achieve on-line analysis.

[0004] The traditional Gas Chromatography-Mass Spectrometry (GC-MS) mainly realizes the mass spectrometry detection of volatile and semi-volatile organic compounds dissolved in liquid samples through an Electron Impact Ionization (EI) source. While the Liquid Chromatography-Mass Spectrometry (LC-MS) mainly uses an Electrospray Ionization (ESI) source for ionizing and detecting organic compounds with strong polarity or low volatility dissolved in liquid samples. Therefore, due to the differences (limitations) in the detection ranges of GC-MS and LC-MS, a single instrument is difficult to cover the comprehensive analysis requirements of organic compounds in liquid samples. Summary of the Invention

[0005] To solve the above problems, the technical solution adopted in this application is as follows: A dual ionization source mass spectrometer is provided, which includes a proton transfer reaction ionization source, an electrospray ionization source, and an on-line flow purge injection system; the on-line flow purge injection system is used to separate liquid samples, and the volatile or semi-volatile organic compounds separated are introduced into the proton transfer reaction ionization source, and the separated liquid is introduced into the electrospray ionization source; the electrospray ionization source is used to perform spray ionization on the non-volatile or strongly polar organic compounds in the separated liquid; the proton transfer reaction ionization source is used to ionize the volatile and semi-volatile organic compounds and perform mass spectrometry analysis, and to perform mass spectrometry analysis on the non-volatile or strongly polar organic compounds after spray ionization.

[0006] Optionally, the proton transfer reaction ionization source includes a microwave-induced plasma reagent ion generation source, a quartz tube, and an ion funnel type proton transfer reaction cell. The microwave-induced plasma reagent ion generation source is used to generate water reagent ions. The input end of the microwave-induced plasma reagent ion generation source is connected to the quartz tube, and the output end is connected to the ion funnel type proton transfer reaction cell.

[0007] Optionally, the ion funnel type proton transfer reaction cell is sequentially connected to a quadrupole ion guide, an electrostatic lens, and a time-of-flight mass analyzer.

[0008] Optionally, a pinch valve is provided on the quartz tube.

[0009] Optionally, it further includes a vacuum chamber and a three-way solenoid valve. The ion funnel type proton transfer reaction cell is located in the vacuum chamber. The first interface of the three-way solenoid valve is communicated with the vacuum chamber. The second interface and the third interface of the three-way solenoid valve are respectively connected to a capillary and the on-line flow purge injection system. The capillary is disposed opposite to the electrospray ionization source.

[0010] Optionally, the on-line flow purge injection system is communicated with the third interface through a pipeline.

[0011] Optionally, the capillary is a stainless steel capillary.

[0012] Optionally, the on-line flow purge injection system includes a sample tank. The bottom of the sample tank is provided with a sample inlet, a carrier gas inlet, and a liquid outlet. The top of the sample tank is communicated with the third interface of the three-way solenoid valve through a pipeline. The liquid outlet is connected to the electrospray ionization source.

[0013] The beneficial effects of the dual ionization source mass spectrometer provided by this application are as follows: Compared with the prior art, this application combines two ionization sources, proton transfer reaction (PTR) and electrospray ionization (ESI), and through an on-line flow purge injection system, the same mass spectrometer can simultaneously analyze volatile, semi-volatile, non-volatile and strongly polar organic compounds in liquid samples, realizing rapid, real-time and comprehensive on-line monitoring of liquid-phase organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0015] Figure 1 It is a schematic structural diagram of the dual ionization source mass spectrometer provided by the embodiment of this application;

[0016] Figure 2 It is a schematic diagram of the working principle of the dual ionization source mass spectrometer provided by the embodiment of this application;

[0017] Among them, the reference numerals in the drawings are as follows:

[0018] 1. Microwave-induced plasma reagent ion generation source; 2. Electrospray ionization source; 3. On-line flow purge injection system; 4. Sample tank; 5. Three-way solenoid valve; 6. Capillary; 7. Pipeline; 8. Pinch valve; 9. Quartz tube; 10. Ion funnel type proton transfer reaction cell; 11. Vacuum chamber; 12. Injection port; 13. Carrier gas inlet; 14. Liquid outlet; 15. Ion funnel; 16. Quadrupole ion guide; 17. Electrostatic lens; 18. Time-of-flight mass analyzer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer, the following further details this application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0020] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0021] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.

[0022] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0023] Traditional gas chromatography-mass spectrometry (GC-MS) mainly realizes the mass spectrometry detection of volatile and semi-volatile organic compounds dissolved in liquid samples through an electron impact ionization source (EI). While liquid chromatography-mass spectrometry (LC-MS) mainly uses an electrospray ionization source (ESI) for ionizing and detecting organic compounds with strong polarity or low volatility dissolved in liquid samples. Therefore, due to the differences (limitations) in the detection ranges of GC-MS and LC-MS respectively, a single instrument is difficult to cover the comprehensive analysis requirements of organic compounds in liquid samples. The traditional off-line mass spectrometer analysis methods and current domestic and foreign standards are shown in Table 1:

[0024] Table 1 Summary of Traditional Off-line Mass Spectrometer Analysis Methods and Current Domestic and Foreign Standards

[0025]

[0026]

[0027] Please refer to Figure 1 and Figure 2 together, and now the dual ionization source mass spectrometer provided by the embodiments of the present application will be described.

[0028] A dual ionization source mass spectrometer, comprising a proton transfer reaction ionization source, an electrospray ionization source 2, and an on-line flow purge injection system 3; the on-line flow purge injection system 3 is used for separating liquid samples, wherein the separated volatile or semi-volatile organic compounds are introduced into the proton transfer reaction ionization source, and the separated liquid is introduced into the electrospray ionization source 2; the electrospray ionization source 2 is used for spray ionization of non-volatile or strongly polar organic compounds in the separated liquid; the proton transfer reaction ionization source is used for ionizing volatile and semi-volatile organic compounds and performing mass spectrometry analysis, and for performing mass spectrometry analysis on the non-volatile or strongly polar organic compounds after spray ionization.

[0029] In this application, the on-line flow purge injection system 3 is used to separate liquid samples, wherein the separated volatile or semi-volatile organic compounds are introduced into the proton transfer reaction ionization source, and the separated liquid is introduced into the electrospray ionization source 2. The electrospray ionization source 2 performs spray ionization on the non-volatile or strongly polar organic compounds in the separated liquid. The proton transfer reaction ionization source ionizes volatile and semi-volatile organic compounds and performs mass spectrometry analysis, and performs mass spectrometry analysis on non-volatile or strongly polar organic compounds, realizing that the same mass spectrometer can simultaneously analyze volatile, semi-volatile, non-volatile and strongly polar organic compounds in liquid samples, and realizing rapid, real-time and comprehensive on-line monitoring of liquid-phase organic pollutants.

[0030] In some embodiments of this application, refer to Figure 1 , the proton transfer reaction ionization source includes a microwave-induced plasma reagent ion generation source 1, a quartz tube 9, and an ion funnel-type proton transfer reaction cell 10. The microwave-induced plasma reagent ion generation source 1 is used to generate water reagent ions. The input end of the microwave-induced plasma reagent ion generation source 1 is connected to the quartz tube 9, and the output end is connected to the ion funnel-type proton transfer reaction cell 10.

[0031] The quartz tube 9 is used to introduce water vapor into the microwave-induced plasma reagent ion generation source 1. The microwave-induced plasma reagent ion generation source 1 is used to generate water reagent ions required for proton transfer reaction. The ion funnel-type proton transfer reaction cell 10 is used for the proton transfer reaction between water reagent ions and sample molecules.

[0032] In some other embodiments of this application, other structures can also be selected for reagent ion generation, such as double hollow cathode discharge or corona discharge, which are not limited in this application.

[0033] In some embodiments of this application, refer to Figure 2, the ion funnel type proton transfer reaction cell 10 is sequentially connected to a quadrupole ion guide 15, an electrostatic lens 16, and a time-of-flight mass analyzer 17. In this embodiment, the ion funnel type proton transfer reaction cell 10, the quadrupole ion guide 15, and the electrostatic lens 16 constitute an ion guiding system. Among them, the ion funnel type proton transfer reaction cell 10 has both the function of ion funnel ion guiding and transmission, and the function of the proton transfer reaction cell to perform the reaction between reagent ions and sample molecules. The time-of-flight mass analyzer 17 is used for mass spectrometry analysis of volatile / semi-volatile organic compounds, non-volatile and strongly polar organic compounds.

[0034] In some embodiments of the present application, refer to Figure 1 , a pinch valve 8 is provided on the quartz tube 9. The communication state of the quartz tube 9 can be controlled through the pinch valve 8, so as to control whether water vapor is introduced into the microwave-induced plasma reagent ion source 1.

[0035] In some embodiments of the present application, refer to Figure 1 , the on-line flow purge injection system 3 includes a sample tank 4. The bottom of the sample tank 4 is provided with an injection port 12, a carrier gas inlet 13, and a liquid outlet 14. The top of the sample tank 4 is connected to the third interface of a three-way solenoid valve 5 through a pipeline, and the liquid outlet 14 is connected to an electrospray ionization source 2.

[0036] The liquid sample to be analyzed can enter the sample tank 4 through the injection port 12. An inert gas (such as helium) can be introduced through the carrier gas inlet 13 to perform on-line purge on the liquid sample. Volatile / semi-volatile organic compounds can be introduced into the ion funnel type proton transfer reaction cell 10 through the pipeline 7 for proton transfer reaction ionization. The separated liquid to be measured is introduced into the electrospray ionization source 2 through the liquid outlet 14 for electrospray ionization of non-volatile / strongly polar organic compounds.

[0037] In some embodiments of the present application, refer to Figure 1 , further includes a vacuum chamber 11 and a three-way solenoid valve 5. The vacuum chamber 11 can provide the necessary vacuum environment for the operation of the mass spectrometer. The ion funnel type proton transfer reaction cell 10 is located in the vacuum chamber 11. The first interface of the three-way solenoid valve 5 is connected to the vacuum chamber 11. The second interface and the third interface of the three-way solenoid valve 5 are respectively connected to a capillary 6 and an on-line flow purge injection system 3, and the capillary 6 is disposed opposite to the electrospray ionization source 2.

[0038] When the third interface of the three-way solenoid valve 5 is opened, it is connected to the vacuum chamber 11 in the on-line flow purge injection system 3. The volatile / semi-volatile organic compounds precipitated in the on-line flow purge injection system 3 are introduced into the ion funnel-type proton transfer reaction cell 10 for proton transfer ionization reaction and further perform mass spectrometry analysis. When the second interface is opened, an electrospray ionization reaction is performed on the liquid sample separated in the on-line flow purge injection system 3 to ionize the non-volatile / strongly polar organic compounds. The ions after electrospray ionization are introduced into the vacuum chamber 11 through the capillary 6 and are repelled into the ion funnel-type proton transfer reaction cell 10 by a DC or pulsed electrode for further mass spectrometry analysis.

[0039] In some embodiments of the present application, refer to Figure 1 , the on-line flow purge injection system 3 is connected to the third interface through a pipeline 7.

[0040] The pinch valve 8 and the three-way solenoid valve 5 can be synchronously controlled. When the pipeline 7 and the quartz tube 9 are opened synchronously, proton transfer reaction-mediated ionization and mass spectrometry analysis of volatile / semi-volatile organic compounds are performed. When the second interface is opened to connect the capillary 6 to the vacuum chamber 11, the quartz tube 9 is closed, and ionization and mass spectrometry analysis of non-volatile / strongly polar organic compounds mediated by the electrospray ionization source 2 are performed.

[0041] In some embodiments of the present application, the capillary 6 is a stainless steel capillary 6. Optionally, the capillary 6 can also be made of other materials, which is not limited in the present application.

[0042] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dual ionization source mass spectrometer, characterized in that: The invention comprises a proton transfer reaction ionization source, an electrospray ionization source and an online flow purge injection system; the system is used to separate liquid samples, wherein the separated volatile or semi-volatile organic matter is introduced into the proton transfer reaction ionization source, and the separated liquid is introduced into the electrospray ionization source; the electrospray ionization source is used to spray ionize the non-volatile or highly polar organic matter in the separated liquid; the proton transfer reaction ionization source is used to ionize the volatile and semi-volatile organic matter and perform mass spectrometry analysis, and to perform mass spectrometry analysis on the non-volatile or highly polar organic matter after spray ionization.

2. The dual ionization source mass spectrometer according to claim 1, characterized in that: The proton transfer reaction ionization source comprises a microwave induced plasma reagent ion generating source, a quartz tube and an ion funnel type proton transfer reaction cell. The microwave induced plasma reagent ion generating source is used to generate water reagent ions. The input end of the microwave induced plasma reagent ion generating source is connected to the quartz tube, and the output end is connected to the ion funnel type proton transfer reaction cell.

3. The dual ionization source mass spectrometer according to claim 2, characterized in that: The ion funnel type proton transfer reaction cell is sequentially connected with a quadrupole ion guide, an electrostatic lens and a time-of-flight mass analyzer.

4. The dual ionization source mass spectrometer according to claim 2, characterized in that: The quartz tube is provided with a pinch valve.

5. The dual ionization source mass spectrometer according to claim 2, characterized in that: It also includes a vacuum chamber and a three-way solenoid valve, the ion funnel-type proton transfer reaction cell is located in the vacuum chamber, the first interface of the three-way solenoid valve is connected to the vacuum chamber, the second interface and the third interface of the three-way solenoid valve are respectively connected to a capillary and the online flow purge injection system, and the capillary is arranged opposite to the electrospray ionization source.

6. The dual ionization source mass spectrometer according to claim 5, characterized in that: The capillary is a stainless steel capillary.

7. The dual ionization source mass spectrometer according to claim 6, characterized in that: The online flow purge injection system comprises a sample tank, the bottom of which is provided with an injection port, a carrier gas inlet and a liquid outlet, the top of which is connected to the third interface of the three-way solenoid valve through a pipeline, and the liquid outlet is connected to the electrospray ionization source.

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