Ion source, mass spectrometry detection system and mass spectrometry detection method

Abstract

An ion source, a detection system including the ion source and a method thereof, wherein the ion source comprises an ionization generator based on real-time direct analysis (i.e., a positive pressure in-situ source DI), an ionization generator based on dielectric channel discharge (i.e., a negative pressure in-situ source SI), a connector, an injection rail and an external vacuum pump. The ion source is an in-situ mass spectrometry combined source, suitable for volatile alkanes, polycyclic aromatic hydrocarbons, volatile organic compounds (VOCs), aromatic compounds, and non-volatile liquid, solid and various special-shaped samples, with a polarity range covering non-polar, weak polar, medium polar and strong polar, and can be connected with mainstream laboratory mass spectrometers, small vehicle-mounted mass spectrometers and portable mobile mass spectrometers.

Description

Technical Field

[0001] The present application relates to an ion source, a mass spectrometry detection system and a mass spectrometry detection method, and specifically to an atmospheric pressure mass spectrometry ion source with a positive and negative pressure combination arrangement, a mass spectrometry detection system and a method thereof. Background Art

[0002] In-situ mass spectrometry (Ambient Ionization Mass Spectrometry, AIMS for short) technology is one of the current hot spots in mass spectrometry theory and application research. Since its emergence, it has always led the industry trend, occupied the headlines of analytical science, and rapidly penetrated into various industries of clinical testing and analytical testing, deeply affecting the application and iterative development of technical equipment. This type of technology does not require or only requires simple sample preparation. It can directly sample samples at room temperature and pressure for in-situ analysis, which is a major change in the field of mass spectrometry analysis. In the past decade, in-situ mass spectrometry technology has been rapidly applied to safety testing and quality control in fields such as food, medicine, materials, physical evidence, environment, and health. Its application has also developed rapidly in the fields of omics analysis, new drug development, analysis of traditional Chinese medicine and natural products, and biomolecular imaging.

[0003] As a bright pearl in the high-tech equipment manufacturing industry, AIMS is advancing towards miniaturization and portability. It has entered certain market supervision industries as a key vehicle-mounted equipment to carry out high-throughput food, drug and poison rapid testing. On the other hand, AIMS has greatly enhanced the potential of high-end mass spectrometry equipment, making it more convenient to use powerful mass spectrometer experimental machines to serve food and drug safety, legal inspection and poison testing, precision medicine, inspection and quarantine, and health big data management. AIMS is considered to be the modern mass spectrometry science with the greatest chance of popularization as a civilian technology.

[0004] At present, most of the commercialized mature in-situ ion source products on the market are imported products with high cost prices, and are mainly used for the detection of a certain type of compounds, such as polar compounds or volatile organic compounds. In addition, when facing different application fields, the current in-situ mass spectrometry technology needs to switch ionization technology to better adapt to the properties of its compounds, and it is impossible to be comprehensive. Therefore, the application of traditional mass spectrometry methods and in-situ mass spectrometry technology in the simultaneous detection of various compounds is still blank.

[0005] Therefore, it is currently necessary to design an ion source that integrates different ionization technologies, which can not only improve the detection capability of traditional mass spectrometry, but also solve problems that could only be solved by multiple methods in the past with one technical product, saving costs and improving efficiency. Therefore, the invention of a broad-spectrum and efficient atmospheric pressure mass spectrometry ion source has significant practical significance. Summary of the invention

[0006] The present application provides an ion source, a detection system including the ion source, and a method for mass spectrometry analysis using the detection system. The positive and negative pressure ion sources can be arranged and combined, and in-situ combined ionization is performed to connect quantitative mass spectrometry or high-resolution qualitative mass spectrometry for detection. Sample pretreatment is unnecessary or greatly simplified, breaking through the limitations of mass spectrometry application scenarios and the bottleneck of analysis objects, and can achieve high-throughput rapid detection and cruise monitoring in the fields of food and medicine, materials, physical evidence, environment, health, agriculture, trade, etc.

[0007] The present application provides an ion source, including an ionization generator based on real-time direct analysis (i.e., a positive pressure in-situ source DI), an ionization generator based on medium channel discharge (i.e., a negative pressure in-situ source SI), a connector, an injection guide rail, and an external vacuum pump. Among them:

[0008] The positive pressure in-situ source DI and the injection guide are installed on the convex load-bearing platform on one side of the connecting piece, and the negative pressure in-situ source SI is located in the sealing area on the other side of the connecting piece; the connecting piece has two functions of "connection" and "sealing", and the convex load-bearing platform and the sealing area are integrally formed or are a split combination;

[0009] The injection guide is placed between the positive pressure in-situ source DI and the negative pressure in-situ source SI, and the positive pressure in-situ source DI and the negative pressure in-situ source SI are located on the same axis; the external vacuum pump is connected to the sealing area of ​​the connector through an air pipe.

[0010] In an exemplary embodiment, the positive pressure in-situ source DI and the negative pressure in-situ source SI are individually controlled by respective control programs.

[0011] In an exemplary embodiment, the positive pressure in-situ source DI includes an air inlet, a main body, and an air outlet. The air inlet and the air outlet are respectively located at two ends of the positive pressure in-situ source DI and the air outlet is adjacent to the injection rail.

[0012] In an exemplary embodiment, the main body of the positive pressure in-situ source DI includes a discharge path for the circulation of working gas, a discharge device located in the middle of the discharge path, a heater close to the gas outlet, and a gate electrode located at the gas outlet; wherein, the discharge voltage of the discharge device when working is 1000-6000V, the heating temperature of the heater is 50-600°C, and the working voltage of the gate electrode is 0-600V; the working gas filled in the positive pressure in-situ source DI can be helium, nitrogen or argon, and its flow rate is 1-5L / min; the gate electrode is used to filter out the opposite polarity ions generated by the discharge.

[0013] In an exemplary embodiment, the gas inlet end of the positive pressure in-situ source DI is connected to a pressure control device for pressurizing the working gas in the positive pressure in-situ source DI.

[0014] In an exemplary embodiment, a discharge passage is provided inside the negative pressure in-situ source SI for the circulation of the working gas inside the negative pressure in-situ source SI, and the negative pressure in-situ source SI is externally connected to a discharge device; the discharge passage of the negative pressure in-situ source SI and the discharge passage of the positive pressure in-situ source DI are located on the same axis; the inner diameter of the discharge passage of the negative pressure in-situ source SI is 0.5-1.5mm, and the discharge voltage thereof during operation is 0-1600V; the working gas filled in the discharge passage of the negative pressure in-situ source SI may be air, nitrogen, helium, argon or carbon dioxide, and the flow rate thereof is 0.02-1L / min.

[0015] In an exemplary embodiment, under the action of the external vacuum pump, the pressure of the working gas inside the negative pressure in-situ source SI is lower than the atmospheric pressure.

[0016] In an exemplary embodiment, the ion source is used to detect non-volatile organic samples; preferably, the ion source is used to detect samples that are easily ionized, such as liquid samples or solid samples or various types of special samples selected from one or more of the following compounds: weak polar compounds, medium polar compounds and strong polar compounds; preferably, the ion source is used to detect non-polar compounds that are difficult to ionize (such as alkanes or polycyclic aromatic hydrocarbons).

[0017] In an exemplary embodiment, the ion source is suitable for detecting volatile organic compounds.

[0018] In an exemplary embodiment, the ion source can be connected to a laboratory mass spectrometer, a small vehicle-mounted mass spectrometer, a portable mobile mass spectrometer, etc.

[0019] The present application also provides a mass spectrometry detection system, comprising an ion source and a mass spectrometer; the ion source is connected to an injection port of the mass spectrometer via a connector, thereby forming a seal with the injection port of the mass spectrometer to transmit ions, wherein:

[0020] The connecting piece is fixed to the injection port of the mass spectrometer by a fastening device, and the sealing area of ​​the connecting piece is close to the injection port of the mass spectrometer;

[0021] The discharge path in the positive pressure in-situ source DI and the discharge path in the negative pressure in-situ source SI in the ion source are located on the same axis as the mass spectrometer injection port.

[0022] In an exemplary embodiment, the fastening device is a bolt fixing device, a rotating shaft fixing device, a locking fixing device, etc., and the fastening device matches the shape and structure of the mass spectrometer injection port.

[0023] In an exemplary embodiment, the mass spectrometer is in a vacuum condition when working, and the mass spectrometer can be a miniaturized mass spectrometer launched by a mainstream manufacturer, and the vacuum degree of its core components such as the mass analyzer and the detector is equal to or higher than 10 -3 torr, the fore-stage vacuum of the ion transmission part is equal to or higher than 10 -1 torr.

[0024] The present application also provides a mass spectrometry detection method, wherein the method uses a mass spectrometry detection system including an ion source and a mass spectrometer for detection, and the method includes:

[0025] a. The sample is introduced into the injection interval through the injection guide in the ion source for ionization, and the injection interval is located between the outlet of the positive pressure in-situ source DI and the negative pressure in-situ source SI of the ion source, and is perpendicular to the coaxial axis of the discharge path of the positive pressure in-situ source DI and the discharge path of the negative pressure in-situ source SI;

[0026] b. According to the properties of the sample, the working states of the positive pressure in-situ source DI and the negative pressure in-situ source SI are switched as follows:

[0027] (1) On-off: The working state of the positive pressure in-situ source DI is on, so as to excite and thermally desorb the sample and ionize it at the same time; the negative pressure in-situ source SI is off, and only serves as an ion channel. The ions generated by the positive pressure in-situ source DI are pulled by an external vacuum pump and directly pass through the negative pressure in-situ source SI; at this time, the discharge voltage of the positive pressure in-situ source DI is 1000V, the heater temperature is 200-400°C, and the voltage of the gate electrode at the outlet is 200-300V; the discharge voltage of the negative pressure in-situ source SI is 0V;

[0028] (2) On-On: The positive pressure in-situ source DI state is on to excite and thermally desorb the sample and ionize it at the same time, and the negative pressure in-situ source SI state is on to continue to ionize some neutral molecules that are missed or insufficiently ionized by the positive pressure in-situ source DI; at this time, the positive pressure in-situ source DI discharge voltage is 1000V, the heater temperature is 200-400°C, the voltage of the gate electrode at the gas outlet is 200-300V, and the negative pressure in-situ source SI discharge voltage is 1500V;

[0029] (3) Off - the positive pressure in-situ source DI state is off, so as to utilize the thermal desorption function of the positive pressure in-situ DI to assist in the extrusion of sample molecules, and the negative pressure in-situ source SI state is on, and the sample is introduced into the negative pressure in-situ source SI by an external vacuum pump for ionization; at this time, the positive pressure in-situ source DI discharge voltage is 0V, the heater temperature is 200-400°C, the voltage of the gate electrode at the gas outlet is 0V, and the negative pressure in-situ source SI discharge voltage is 1500V;

[0030] (4) Off-Off: The positive pressure in-situ source DI and the negative pressure in-situ source SI are both in the off state, and the discharge voltages of the positive pressure in-situ source DI and the negative pressure in-situ source SI are both 0V;

[0031] c. The ions generated in step b enter the mass spectrometer injection port, and then generate a mass spectrometer signal.

[0032] In the present application, "positive pressure in-situ source DI" or "ionization generator based on real-time direct analysis" refers to an ion source that uses direct current discharge to excite inert gases such as nitrogen or helium to generate a plasma containing excited substances, and then eliminates the opposite polarity ions generated during the discharge process through the gate electrode at the gas outlet, retains the excited non-ionic substances, and then collides and desorbs the molecules on the surface of the sample to be tested, and instantly generates a gas phase ionization reaction. This process drives ionization through kinetic energy, and the ionization efficiency is relatively high. Initial data show that the ionization rate is as high as 3% (compared to the ionization rate of ESI ≤1%). Positive pressure ionization can reserve a sufficiently large ionization range to facilitate sample introduction, and rely on temperature difference and kinetic energy to squeeze out the sample surface, especially the organic molecules (even non-volatile molecules and metal organic molecules such as organic selenium) on the surface of large-volume solid samples.

[0033] In this application, "negative pressure in-situ source SI" or "ionization generator based on dielectric channel discharge" refers to an ion source that uses alternating current excitation combined with atmospheric pressure photoionization to ionize the incoming gaseous material online and generate molecular ion signals. This setting greatly improves the ion collection efficiency, that is, the ionization zone and the ion collection zone are located in the same place, avoiding molecular loss and ion signal divergence. The advantages of this process include unique high-efficiency ion collection and unattended, non-intermittent, 24 / 7 fully automatic operation, and no external gas or auxiliary solvent is required.

[0034] The present application utilizes the above-mentioned ion source to realize the detection of a wide spectrum of sample forms (gas, liquid, and solid) in a full polarity range from non-polar (such as alkanes, etc.), weak polar (such as aroma components), medium polar (such as drugs or amino acids), to strong polar (such as ionic liquids, etc.) through in-situ ionization.

[0035] The ion source and mass spectrometry detection structure / method of the present application have many advantages, making mass spectrometry analysis "softer, more direct, faster, and more economical". Among them, the ion source / mass spectrometry detection system / method of the present application has the following advantages:

[0036] (1) Direct analysis: basically no sample preparation is required, and conventional solid or liquid samples can be completed from injection to generation of mass spectrometry signals within 10 seconds, meeting the needs of modern society for high-throughput rapid analysis;

[0037] (2) Easy operation and labor saving: the working parameters are fixed, no adjustment is required, no specialized knowledge is required to optimize the operation, and the analysis results can be obtained directly;

[0038] (3) Green and low-carbon: The analysis process requires almost no chemical solvents, which is more convenient for vehicle loading and reduces external pollution sources;

[0039] (4) It can analyze not only liquid and solid samples (such as tablets, leaves, powders, edible oils, foods, agricultural products, aquatic products, toys, and packaging materials), but also gaseous samples (such as odors or flavors);

[0040] (5) It can ionize highly polar, medium polar, and weak polar compounds (such as drugs, poisons, and pesticide residues); it is also sensitive and effective for non-polar compounds that are difficult to ionize (such as alkanes and polycyclic aromatic hydrocarbons), and does not require the sample to be dissolved in advance like ESI or MALDI;

[0041] (6) No adducted salt ions are produced, only singly charged ions are generated; the integrity of the molecular ions is maintained without fragmentation, which simplifies the preparation of spectral libraries, quantitative analysis, and spectrum interpretation;

[0042] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0044] Figure 1 The working principle diagram of the mass spectrometry detection system for this application;

[0045] Figure 2 This is the design diagram of the ion source (split type) of this application;

[0046] Figure 3 A physical diagram of the split connector of the present application;

[0047] Figure 4 The mass spectrometry detection system (split type) of the present application is shown;

[0048] Figure 5 The connection relationship between the positive pressure in-situ source DI and the negative pressure in-situ source SI in the ion source (split type) of the present application is shown;

[0049] Figure 6 This is the design drawing of the ion source (integrated) of this application;

[0050] Figure 7 The results of testing edible oil samples using the mass spectrometry detection method in this application are shown;

[0051] Figure 8 The results of detecting lysine samples using the mass spectrometry detection method in this application are shown;

[0052] Fig. 9 The results of principal component analysis of soy sauce and vinegar samples using the mass spectrometry detection method in this application are shown;

[0053] Fig.10 The results of principal component analysis of liquor samples using the mass spectrometry detection method in this application are shown.

[0054] Description of reference numerals:

[0055] 1: DI source body; 2: SI source body; 3: DI source air inlet; 4: DI source air outlet; 5: Connector load-bearing platform; 6: Injection guide rail; 7: Sample module; 8: Connector sealing area; 9: Connector fastening device; 10: External vacuum pump; 11: Mass spectrometer inlet. DETAILED DESCRIPTION

[0056] The present application describes multiple embodiments, but the description is exemplary rather than restrictive, and it is obvious to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present application. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0057] The present application provides an ion source, including an ionization generator based on real-time direct analysis (i.e., a positive pressure in-situ source DI), an ionization generator based on medium channel discharge (i.e., a negative pressure in-situ source SI), a connector, an injection guide rail, and an external vacuum pump. Among them:

[0058] The positive pressure in-situ source DI and the injection guide are installed on the convex load-bearing platform on one side of the connecting piece, and the negative pressure in-situ source SI is located in the sealing area on the other side of the connecting piece; the connecting piece has two functions of "connection" and "sealing", and the convex load-bearing platform and the sealing area are integrally formed or are a split combination;

[0059] The injection guide is placed between the positive pressure in-situ source DI and the negative pressure in-situ source SI, and the positive pressure in-situ source DI and the negative pressure in-situ source SI are located on the same axis; the external vacuum pump is connected to the sealing area of ​​the connector through an air pipe.

[0060] In an exemplary embodiment, the positive pressure in-situ source DI and the negative pressure in-situ source SI are individually controlled by respective control programs.

[0061] In an exemplary embodiment, the positive pressure in-situ source DI includes an air inlet, a main body, and an air outlet. The air inlet and the air outlet are respectively located at two ends of the positive pressure in-situ source DI and the air outlet is adjacent to the injection rail.

[0062] In an exemplary embodiment, the main body of the positive pressure in-situ source DI includes a discharge path for the circulation of working gas, a discharge device located in the middle of the discharge path, a heater close to the gas outlet, and a gate electrode located at the gas outlet; when working, the discharge voltage of the discharge device is 1000-6000V, the heating temperature of the heater is 50-600°C, and the working voltage of the gate electrode is 0-600V; the working gas filled in the positive pressure in-situ source DI can be helium, nitrogen, or argon, and the flow rate is 1-5L / min; the gate electrode is used to filter out the opposite polarity ions generated by the discharge.

[0063] In an exemplary embodiment, a pressure control device is connected to one side of the gas inlet of the positive pressure in-situ source DI to pressurize the working gas in the positive pressure in-situ source DI.

[0064] In an exemplary embodiment, the negative pressure in-situ source SI is externally connected to a discharge device, a discharge passage is provided inside the negative pressure in-situ source SI for the circulation of the working gas inside the negative pressure in-situ source SI, and the discharge passage of the negative pressure in-situ source SI and the discharge passage of the positive pressure in-situ source DI are located on the same axis; the inner diameter of the discharge passage of the negative pressure in-situ source SI is 0.5-1.5mm, and the discharge voltage during operation is 0-1600V; the working gas of the negative pressure in-situ source SI can be air, nitrogen, helium, argon or carbon dioxide, and the flow rate is 0.02-1L / min.

[0065] In an exemplary embodiment, under the action of the external vacuum pump, the pressure of the working gas inside the negative pressure in-situ source SI is lower than the atmospheric pressure.

[0066] In an exemplary embodiment, the ion source is used to detect non-volatile organic samples; preferably, the ion source is used to detect samples that are easily ionized, such as liquid samples or solid samples or various types of special samples selected from one or more of the following compounds: weak polar compounds, medium polar compounds and strong polar compounds; preferably, the ion source is used to detect non-polar compounds that are difficult to ionize (such as alkanes or polycyclic aromatic hydrocarbons).

[0067] In an exemplary embodiment, the ion source is suitable for detecting volatile organic compounds.

[0068] In an exemplary embodiment, the ion source can be connected to a laboratory mass spectrometer, a small vehicle-mounted mass spectrometer, a portable mobile mass spectrometer, etc.

[0069] The present application also provides a mass spectrometry detection system, comprising an ion source and a mass spectrometer; the ion source is connected to an injection port of the mass spectrometer via a connector, thereby forming a seal with the injection port of the mass spectrometer to transmit ions, wherein:

[0070] The connecting piece is fixed to the injection port of the mass spectrometer by a fastening device, and the sealing area of ​​the connecting piece is adjacent to the injection port of the mass spectrometer;

[0071] The discharge path in the positive pressure in-situ source DI and the discharge path in the negative pressure in-situ source SI in the ion source are located on the same axis as the mass spectrometer injection port.

[0072] In an exemplary embodiment, the fastening device is fixed by bolts and a rotating shaft and matches the shape and structure of the mass spectrometer injection port.

[0073] In an exemplary embodiment, the mass spectrometer is in a vacuum condition when working, and the mass spectrometer can be a miniaturized mass spectrometer launched by a mainstream manufacturer, and the vacuum degree of its core components such as the mass analyzer and the detector is equal to or higher than 10 -3 torr, the fore-stage vacuum of the ion transmission part is equal to or higher than 10 -1 torr.

[0074] The present application also provides a mass spectrometry detection method, wherein the method uses a mass spectrometry detection system including an ion source and a mass spectrometer for detection, and the method includes:

[0075] a. The sample is introduced into the injection interval through the injection guide in the ion source for ionization, and the injection interval is located between the outlet of the positive pressure in-situ source DI and the negative pressure in-situ source SI of the ion source, and is perpendicular to the coaxial axis of the discharge path of the positive pressure in-situ source DI and the discharge path of the negative pressure in-situ source SI;

[0076] b. According to the properties of the sample, the working states of the positive pressure in-situ source DI and the negative pressure in-situ source SI are switched as follows:

[0077] (1) On-off: The working state of the positive pressure in-situ source DI is on, so as to excite and thermally desorb the sample and ionize it at the same time; the negative pressure in-situ source SI is off, and only serves as an ion channel. The ions generated by the positive pressure in-situ source DI are pulled by an external vacuum pump and directly pass through the negative pressure in-situ source SI; at this time, the discharge voltage of the positive pressure in-situ source DI is 1000V, the heater temperature is 200-400°C, and the voltage of the gate electrode at the outlet is 200-300V; the discharge voltage of the negative pressure in-situ source SI is 0V;

[0078] (2) On-On: The positive pressure in-situ source DI state is on to excite and thermally desorb the sample and ionize it at the same time, and the negative pressure in-situ source SI state is on to continue to ionize some neutral molecules that are missed or insufficiently ionized by the positive pressure in-situ source DI; at this time, the positive pressure in-situ source DI discharge voltage is 1000V, the heater temperature is 200-400°C, the voltage of the gate electrode at the gas outlet is 200-300V, and the negative pressure in-situ source SI discharge voltage is 1500V;

[0079] (3) Off-On: The positive pressure in-situ source DI is off to utilize the thermal desorption function of the positive pressure in-situ DI to assist in the extrusion of sample molecules, and the negative pressure in-situ source SI is on. The sample is introduced into the negative pressure in-situ source SI by an external vacuum pump for ionization. At this time, the discharge voltage of the positive pressure in-situ source DI is 0 V, the heater temperature is 200-400 ° C, the voltage of the gate electrode at the outlet is 0 V, and the discharge voltage of the negative pressure in-situ source SI is 1500 V.

[0080] (4) Off-Off: The positive pressure in-situ source DI and the negative pressure in-situ source SI are both in the off state, and the discharge voltages of the positive pressure in-situ source DI and the negative pressure in-situ source SI are both 0V;

[0081] c. The ions generated in step b enter the mass spectrometer injection port, and then generate a mass spectrometer signal.

[0082] The present invention is further described below by means of specific examples, but is not limited thereto.

[0083] Example 1.

[0084] The detection method of the present application was used to randomly perform mass spectrometry detection on three common brands of edible oils on the market: spicy oil, mustard oil, and pepper oil.

[0085] 10 μL of three edible oil samples, namely spicy oil, mustard oil and Sichuan pepper oil, were randomly selected from common brands on the market and diluted 100 times with n-hexane. The samples were directly dipped into the sample through a glass rod (the injection volume was about 0.5 μL) and then placed in the injection area. The injection of each edible oil sample was repeated three times. The samples were injected sequentially through the injection guide. The detection time for a single sample was about 6 seconds.

[0086] In this process, the working state of the ion source is DI on-SI off, and the specific working parameters are: the positive pressure in-situ source DI discharge voltage is 1000V, the heater temperature is 350℃, and the voltage of the gate electrode at the outlet is 250V; the discharge voltage in the negative pressure in-situ source SI is set to 0V. Figure 7 .

[0087] Conclusion: According to Figure 7 It can be seen that the mass spectrometry detection system and method of the present application can detect liquid samples.

[0088] Example 2.

[0089] The detection method of the present application is used to perform mass spectrometry detection on lysine standards.

[0090] 9 glass rods are used to directly dip (injection volume is about 0.5 microliters) lysine standard with a concentration of 1 μg / mL (solvent is deionized water), put into the injection area, and injected sequentially by the injection guide. In this process, every 3 samples are grouped together, and the working state of the ion source is DI on-SI off ( Figure 8 Left), DI open-SI open ( Figure 8 Middle), DI off-SI on ( Figure 8 The mass spectrometry data are obtained in sequence.

[0091] The specific working parameters are: when DI is on and SI is off, the discharge voltage of the positive pressure in-situ source DI is 1000V, the heater temperature is 300℃, and the voltage of the gate electrode at the outlet is 250V; the discharge voltage of the negative pressure in-situ source SI is 0V. When DI is on and SI is on, the discharge voltage of the positive pressure in-situ source DI is 1000V, the heater temperature is 300℃, and the voltage of the gate electrode at the outlet is 250V; the discharge voltage of the negative pressure in-situ source SI is 1500V. See the test results for details. Figure 8 .

[0092] Conclusion: According to Figure 8 It can be seen that the mass spectrometry detection system and method of the present application can be used to detect liquid organic substances.

[0093] Example 3.

[0094] The detection method of the present application was used to perform mass spectrometry detection on two soy sauce samples, three edible vinegar samples and five small-bottle Chinese liquors.

[0095] Two soy sauce samples, three edible vinegar samples and five small-bottle Chinese liquor samples were directly dipped into the sample by glass rod without any pretreatment (the injection volume was about 0.5 μL), added to the injection area, and injected sequentially by the injection rail. The detection time of a single sample was about 3 seconds, and each sample was injected three times. During this process, the working state of the ion source was: DI off-SI on. The specific working parameters of the ion source were: the discharge voltage of the positive pressure in-situ source DI was 1000V, the heater temperature was 250°C, and the voltage of the gate electrode at the outlet was 0V; the discharge voltage of the negative pressure in-situ source SI was set to 1500V.

[0096] The principal component analysis (PCA) was performed on the data of soy sauce, vinegar and liquor samples, and the results are shown in Figure 9-10 .

[0097] Conclusion: According to Figure 9-10 It can be seen that the mass spectrometry detection system and method of the present application can be used to detect volatile organic compounds.

Claims

1. A mass spectrometry detection method, characterized in that: The method uses a mass spectrometry detection system for detection, and the mass spectrometry detection system includes an ion source and a mass spectrometer, wherein: The ion source includes an ionization generator based on real-time direct analysis, namely a positive pressure in-situ source DI, an ionization generator based on medium path discharge, namely a negative pressure in-situ source SI, a connector, an injection guide rail, and an external vacuum pump, wherein: the positive pressure in-situ source DI and the injection guide rail are installed on an outwardly convex load-bearing platform on one side of the connector, and the negative pressure in-situ source SI is located in a sealing area on the other side of the connector; the outwardly convex load-bearing platform and the sealing area are integrally formed, or are a split combination; the injection guide rail is placed between the positive pressure in-situ source DI and the negative pressure in-situ source SI, and the positive pressure in-situ source DI and the negative pressure in-situ source SI are located on the same axis; the external vacuum pump is connected to the sealing area of ​​the connector through an air pipe; The ion source is connected to the injection port of the mass spectrometer through the connector and forms a seal with the injection port of the mass spectrometer to transmit ions; The connecting piece is fixed to the injection port of the mass spectrometer by a fastening device, and the injection port of the mass spectrometer is located inside the sealing area of ​​the connecting piece; The discharge path in the positive pressure in-situ source DI in the ion source, the discharge path in the negative pressure in-situ source SI and the injection port of the mass spectrometer are located on the same axis; The method comprises: a. The sample is introduced into the injection interval through the injection guide of the ion source, and the injection interval is located between the outlet of the positive pressure in-situ source DI of the ion source and the negative pressure in-situ source SI, and is perpendicular to the coaxial axis of the discharge path of the positive pressure in-situ source DI and the discharge path of the negative pressure in-situ source SI; b. According to the properties of the sample, the working states of the positive pressure in-situ source DI and the negative pressure in-situ source SI are switched as follows: (1) On-off: The working state of the positive pressure in-situ source DI is on, and the state of the negative pressure in-situ source SI is off. The ions generated by the positive pressure in-situ source DI are pulled by the external vacuum pump and enter the negative pressure in-situ source SI. At this time, the discharge voltage of the positive pressure in-situ source DI is 1000V, the heater temperature of the positive pressure in-situ source DI is 200-400°C, and the voltage of the gate electrode at the outlet of the positive pressure in-situ source DI is 200-300V; the discharge voltage of the negative pressure in-situ source SI is 0V; (2) On-On: The state of the positive pressure in-situ source DI is on, and the state of the negative pressure in-situ source SI is on; at this time, the discharge voltage of the positive pressure in-situ source DI is 1000 V, the heater temperature of the positive pressure in-situ source DI is 200-400° C., the voltage of the gate electrode at the outlet of the positive pressure in-situ source DI is 200-300 V, and the discharge voltage of the negative pressure in-situ source SI is 1500 V; (3) Off-On: The state of the positive pressure in-situ source DI is off, and the state of the negative pressure in-situ source SI is on. The sample is introduced into the negative pressure in-situ source SI by the external vacuum pump for ionization. At this time, the discharge voltage of the positive pressure in-situ source DI is 0 V, the heater temperature of the positive pressure in-situ source DI is 200-400° C., the voltage of the gate electrode at the outlet of the positive pressure in-situ source DI is 0 V, and the discharge voltage of the negative pressure in-situ source SI is 1500 V. (4) Off-Off: The states of the positive pressure in-situ source DI and the negative pressure in-situ source SI are both off, and the discharge voltages of the positive pressure in-situ source DI and the negative pressure in-situ source SI are both 0V; c. The ions generated in step b enter the mass spectrometer injection port, and then generate a mass spectrometry signal.

2. The method according to claim 1, characterized in that The positive pressure in-situ source DI and the negative pressure in-situ source SI are individually controlled by their own control programs.

3. The method according to claim 1, characterized in that The positive pressure in-situ source DI comprises an air inlet, a main body and an air outlet. The air inlet and the air outlet are respectively located at two ends of the positive pressure in-situ source DI and the air outlet is adjacent to the injection guide rail.

4. The method according to claim 3, characterized in that A discharge path is arranged inside the main body, comprising a discharge device located in the middle of the discharge path, a heater close to the gas outlet, and a grid electrode located at the gas outlet.

5. The method according to claim 4, characterized in that The positive pressure in-situ source DI is filled with a working gas, the working gas is helium, nitrogen or argon, and the flow rate of the working gas is 1-5 L / min.

6. The method according to claim 5, characterized in that One side of the air inlet is also connected with a pressure control device.

7. The method according to claim 1, characterized in that A discharge path is provided inside the negative pressure in-situ source SI, and a discharge device is externally connected to the negative pressure in-situ source SI.

8. The method according to claim 7, characterized in that The discharge path of the negative pressure in-situ source SI and the discharge path of the positive pressure in-situ source DI are located on the same axis.

9. The method according to claim 7, characterized in that: The discharge path is filled with a working gas, which is air, nitrogen, helium, argon or carbon dioxide, and has a flow rate of 0.02-1 L / min.

10. The method according to claim 7, characterized in that The inner diameter of the discharge path is 0.5-1.5 mm.

11. The method according to claim 7, characterized in that The pressure of the internal gas of the negative pressure in-situ source SI when it is working is less than the atmospheric pressure.

12. The method according to any one of claims 1 to 11, characterized in that: The ion source is used to detect non-volatile organic samples.

13. The method according to claim 12, characterized in that The ion source is used to detect samples that are easily ionized, and the samples that are easily ionized are selected from liquid samples or solid samples of one or more of the following compounds: weak polar compounds, medium polar compounds, or strong polar compounds.

14. The method according to claim 12, characterized in that The ion source is used to detect non-polar compounds that are difficult to ionize, and the non-polar compounds that are difficult to ionize are alkanes or polycyclic aromatic hydrocarbons.

15. The method according to any one of claims 1 to 11, characterized in that: The ion source is used to detect volatile organic compound samples.

16. The method according to any one of claims 1 to 11, characterized in that: The ion source is connected with a laboratory mass spectrometer, a small vehicle-mounted mass spectrometer or a portable mobile mass spectrometer.

17. The method according to any one of claims 1 to 11, characterized in that: The fastening device is a bolt fixing device, a rotating shaft fixing device or a lock fixing device.

Images