A multi-modal online detection system

Abstract

The utility model provides a kind of multi-mode online detection system, comprising: sample injection switching component, shunt component, gas chromatograph and mass spectrometer;The sample injection switching component is equipped with sample injection part and switching valve, and the outlet of the sample injection part is communicated with the inlet of switching valve by pipeline;The outlet of the switching valve is communicated with shunt component, gas chromatograph respectively by pipeline, and control sample enters shunt component or gas chromatograph;The downstream of the shunt component is communicated with the mass spectrometer, and the gas chromatograph includes thermal conductivity detector, and the sample outlet of the thermal conductivity detector is also communicated with shunt component by pipeline.The multi-mode online detection system provided in the present application switches between single mass spectrum and chromatography mass spectrum, which can meet the online detection of unknown gas, and can also quickly and accurately qualitatively and quantitatively determine the gas components of known large dynamic range, and can adapt to different application scenarios and meet the online detection needs of different samples.

Description

Technical Field

[0001] This utility model relates to the field of analytical equipment technology, and in particular to a multi-mode online detection system. Background Technology

[0002] With the development of industries such as petrochemicals, coal chemicals, steel smelting, and natural gas, the requirements for online gas monitoring and control technology in process industries are becoming increasingly stringent. Real-time, rapid, and accurate acquisition of process gas component data is crucial for efficient control of process technologies. Traditional process industry gas component analysis generally uses online chromatographic analysis systems, which suffer from drawbacks such as slow analysis speed, inability to provide real-time analysis, poor qualitative capabilities, especially inability to qualitatively identify unknown substances, inability to perform multi-path analysis, detector selectivity, requirement for carrier gas, and high maintenance costs.

[0003] Mass spectrometry (MS) is widely used in various analytical testing fields due to its ability to accurately characterize unknown substances. Industrial online mass spectrometers can be directly integrated into production lines, featuring fast analysis speed, full-component analysis, multiple flow paths, broad spectrum, and high accuracy. They are particularly suitable for online process monitoring to improve process control and ensure product quality. However, mass spectrometry cannot separate mixed gases. Therefore, analyzing gases with complex compositions requires correction using techniques such as soft ionization and overlapping peak correction algorithms. This is significantly affected by quantitative algorithms, especially for low-abundance samples, where measurement errors are large and ischemic differentiation is difficult. Furthermore, the quantitative accuracy of mass spectrometry is slightly lower than that of chromatographic quantitative analysis, which limits the application scope of pure mass spectrometry technology in industrial process control.

[0004] Gas chromatography-mass spectrometry (GC-MS) is a method that combines gas chromatography separation with mass spectrometry qualitative and quantitative analysis. It leverages chromatographic separation to compensate for the limitations of mass spectrometry in accurately identifying and quantifying complex samples, while utilizing the broad-spectrum advantages of mass spectrometry to overcome the selectivity limitations of chromatographic detectors, achieving a complementary advantage. However, the inherent slowness of chromatographic separation cannot be avoided. Therefore, GC-MS is typically used only as an offline analytical method in laboratories and is difficult to directly apply in industrial online settings. Utility Model Content

[0005] To address the aforementioned technical problems in industrial online detection, this utility model provides a multi-mode online detection system. The multi-mode online detection system provided in this application, by setting up an injection switching component and a flow splitter component, can switch between single-mode mass spectrometry and chromatographic mass spectrometry according to detection needs. It can satisfy both online detection of unknown gases and rapid and accurate qualitative and quantitative analysis of known gas components with a large dynamic range, adapting to different application scenarios and meeting the online detection needs of different samples.

[0006] A multi-mode online detection system includes: an injection switching component, a split component, a gas chromatograph, and a mass spectrometer; The sample injection switching assembly includes an injection component and a switching valve. The outlet of the injection component is connected to the inlet of the switching valve via a pipeline. The outlet of the switching valve is connected to the split assembly and the gas chromatograph via pipelines, respectively, and controls the sample to enter the split assembly or the gas chromatograph. The downstream of the splitting assembly is connected to the mass spectrometer, and the gas chromatograph includes a thermal conductivity detector. The outlet of the thermal conductivity detector is also connected to the splitting assembly via a pipeline.

[0007] Preferably, the sample introduction component is provided with multiple switchable sample entry channels.

[0008] Preferably, the split assembly includes a three-way valve and a mass spectrometer injection split assembly; The three-way valve is connected to the sample outlet, switching valve and mass spectrometer injection split assembly of the gas chromatograph, respectively. The mass spectrometer sample introduction and split assembly is used to split and depressurize the sample and deliver it to the mass spectrometer for detection.

[0009] Preferably, the mass spectrometer sample introduction split assembly consists of a sample introduction split path, a flow-limiting capillary, and a transfer tube connected in sequence, and the outlet of the transfer tube is connected to the sample inlet of the mass spectrometer. The sample injection splitting path is equipped with an empty branch, and the empty branch is equipped with a one-way valve; The transmission tube is provided with an extraction branch, which is connected to a vacuum generator.

[0010] Preferably, the gas chromatograph further includes a rapid chromatographic column and a quantitative loop. The quantitative loop is used to quantify the sample and feed it into the rapid chromatographic column for separation; The thermal conductivity detector is located downstream of the fast chromatographic column and is connected to the splitting assembly.

[0011] Preferably, the gas chromatograph further includes a six-way valve. The two lines of the six-way valve are connected to the inlet and outlet of the quantitative loop, respectively, and the other four lines of the six-way valve are connected to the carrier gas source, the sampling pump, the injection switching assembly, and the rapid chromatography column, respectively; the sampling pump is used to deliver the sample into the quantitative loop; The carrier gas source is also connected to the thermal conductivity detector.

[0012] Preferably, the gas chromatograph includes multiple rapid chromatographic columns connected in series.

[0013] Preferably, the mass spectrometer includes an ion source, a mass analyzer, and a detector. The sample inlet micropore of the ion source is connected to the flow splitting component.

[0014] This application provides a multi-mode online detection system, including: an injection switching component, a split component, a gas chromatograph, and a mass spectrometer. The injection switching component is equipped with an injection element and a switching valve. The outlet of the injection element is connected to the inlet of the switching valve via a pipeline. The outlet of the switching valve is connected to the split component and the gas chromatograph via pipelines, controlling the sample to enter either the split component or the gas chromatograph. If the sample enters the mass spectrometer, single-mode mass spectrometry detection is achieved. The downstream of the split component is connected to the mass spectrometer. The gas chromatograph includes a thermal conductivity detector, and the outlet of the thermal conductivity detector is also connected to the split component via a pipeline. Therefore, the sample separated by the gas chromatograph and detected by the thermal conductivity detector can enter the mass spectrometer for further detection. The multi-mode online detection system provided by this application, by setting up the injection switching component and the split component, can switch between single-mode mass spectrometry and gas chromatography-mass spectrometry according to detection needs. It can satisfy both online detection of unknown gases and rapid and accurate qualitative and quantitative analysis of known gas components with a large dynamic range, adapting to different application scenarios and meeting the online detection needs of different samples. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the connection relationship of the multi-mode online detection system of this utility model; Figure 2 This is a schematic diagram of the multi-mode online detection system of this utility model; Figure 3 A schematic diagram of the shunt component in the multi-mode online detection system of this utility model; Figure reference numerals: 1-Injection switching assembly; 11-Injection port; 12-Switching valve; 2-Split assembly; 21-Three-way valve; 22-Mass spectrometer injection split assembly; 221-Flow limiting capillary; 222-Transfer tube; 223-Evacuation branch; 224-One-way valve; 225-Extraction branch; 3-Gas chromatograph; 31-Thermal conductivity detector; 32-Rapid chromatographic column; 33-Quantitative loop; 34-Six-way valve; 4-Mass spectrometer; 41-Ion source; 42-Mass analyzer; 43-Detector. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0019] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0020] This utility model provides a multi-mode online detection system, including: an injection switching component 1, a split component 2, a gas chromatograph 3, and a mass spectrometer 4; The sample injection switching assembly 1 is provided with an injection component 11 and a switching valve 12. The outlet of the injection component 11 is connected to the inlet of the switching valve 12 through a pipeline. The outlet of the switching valve 12 is connected to the split assembly 2 and the gas chromatograph 3 through pipelines respectively, and controls the sample to enter the split assembly 2 or the gas chromatograph 3. The downstream of the splitting component 2 is connected to the mass spectrometer 4, and the gas chromatograph 3 includes a thermal conductivity detector 31. The sample outlet of the thermal conductivity detector 31 is also connected to the splitting component 2 through a pipeline.

[0021] This application provides a multi-mode online detection system, including: an injection switching component 1, a split component 2, a gas chromatograph 3, and a mass spectrometer 4; the injection switching component 1 is provided with an injection part 11 and a switching valve 12, the outlet of the injection part 11 is connected to the inlet of the switching valve 12 through a pipeline; the outlet of the switching valve 12 is connected to the split component 2 and the gas chromatograph 3 through pipelines respectively, and controls the sample to enter the split component 2 or the gas chromatograph 3, and realizes single mass spectrometry detection when entering the mass spectrometer 4; the downstream of the split component 2 is connected to the mass spectrometer 4, the gas chromatograph 3 includes a thermal conductivity detector 31, the outlet of the thermal conductivity detector 31 is also connected to the split component 2 through a pipeline, so that the sample separated by the gas chromatograph 3 and detected by the thermal conductivity detector 31 can enter the mass spectrometer 4 for further detection. The multi-mode online detection system provided in this application, by setting up an injection switching component 1 and a split component 2, can switch between single mass spectrometry and chromatographic mass spectrometry according to detection needs. It can not only meet the online detection of unknown gases, but also perform rapid and accurate qualitative and quantitative analysis of known gas components with a large dynamic range. It can adapt to different application scenarios and meet the online detection needs of different samples.

[0022] Specifically, for applications with little or no overlapping peaks, single-mass spectrometry mode can be used. For applications with significant overlapping peaks, or where isomers exist and accurate differentiation is required, two modes can be configured: one is a chromatographic separation-mass spectrometry qualitative and quantitative detection mode, and the other is a mixed chromatographic separation-mass spectrometry qualitative and chromatographic quantitative mode. The mixed chromatographic separation-mass spectrometry qualitative and chromatographic quantitative mode utilizes the separation and quantitative detection functions of the gas chromatograph 3 to achieve substance separation and quantitative detection, then combines the advantages of strong mass spectrometry qualitative capability and accurate chromatographic quantification by using mass spectrometry to distinguish the substances corresponding to the quantitative results. Furthermore, by utilizing the non-destructive detection characteristics of the thermal conductivity detector 31 in the gas chromatograph 3, it is organically combined with the mass spectrometer 4, forming multiple analytical modes such as single-mass spectrometry detection, chromatographic separation-mass spectrometry qualitative and quantitative detection, mass spectrometry qualitative and chromatographic quantitative detection, and high-concentration chromatographic mass spectrometry low-concentration detection. This allows for both the detection of unknown gases and accurate qualitative and quantitative analysis of known gases, and provides a high-performance online monitoring device with a large dynamic range. Furthermore, using mass spectrometry for qualitative analysis can reduce the precision requirements for temperature, pressure, and other parameters in rapid chromatography.

[0023] Unlike traditional chromatography-mass spectrometry (GC-MS) instruments that rely solely on chromatographic separation and mass spectrometry for qualitative and quantitative detection, this invention can perform both chromatographic separation-mass spectrometry qualitative and quantitative detection, as well as chromatographic separation-mass spectrometry qualitative and chromatographic quantification. Furthermore, it can also perform multi-channel single-channel mass spectrometry qualitative and quantitative detection. Since chromatography is not used for qualitative analysis, the precision requirements for controlling chromatographic temperature, pressure, flow rate, and flow velocity are significantly reduced, lowering the technical barrier and making it particularly suitable for industrial online detection.

[0024] Preferably, the sample introduction component 11 is provided with multiple switchable sample entry channels.

[0025] The preferred sample introduction component 11 is equipped with multiple switchable sample inlet channels. These sample inlet channels can collect different samples at different locations, and the sample in one channel can be switched for detection by switching; then the other channel can be switched.

[0026] Preferably, the split assembly 2 includes a three-way valve 21 and a mass spectrometer injection split assembly 22; The three-way valve 21 is connected to the sample outlet of the gas chromatograph 3, the switching valve 12, and the mass spectrometer sample injection split assembly 22, respectively. The mass spectrometer sample introduction and split assembly 22 is used to split and depressurize the sample and deliver it to the mass spectrometer 4 for detection.

[0027] The preferred splitting assembly 2 includes a three-way valve 21 and a mass spectrometry injection splitting assembly 22. The three-way valve 21 is connected to the outlet of the gas chromatograph 3, the switching valve 12, and the mass spectrometry injection splitting assembly 22, and two of them can be connected. When the outlet of the gas chromatograph 3 is connected to the mass spectrometry injection splitting assembly 22, the sample separated and / or detected by the gas chromatograph can enter the mass spectrometer for detection (after the sample is split and depressurized by the mass spectrometry injection splitting assembly 22). When the switching valve 12 is connected to the mass spectrometry injection splitting assembly 22, and the switching valve 12 is selected to be directly connected to the opening of the mass spectrometer 4, the sample can be directly sent into the mass spectrometry injection splitting assembly 22, and after splitting and depressurization, it enters the mass spectrometer 4 for detection.

[0028] Preferably, the mass spectrometer sample injection split assembly 22 is sequentially connected to the sample injection split path, the flow-limiting capillary 221, and the transfer tube 222, and the outlet of the transfer tube 222 is connected to the sample inlet of the mass spectrometer 4. The sample injection splitting path is provided with an emptying branch 223, and the emptying branch 223 is provided with a one-way valve 224; The transmission tube 222 is provided with an extraction branch 225, which is connected to the vacuum generator.

[0029] The preferred mass spectrometer injection split assembly 22 is sequentially connected to the injection split path, the flow-limiting capillary 221, and the transfer tube 222. The outlet of the transfer tube 222 is connected to the injection port of the mass spectrometer 4. Whether the sample comes from the gas chromatograph 3 or is directly injected, it flows sequentially through the injection split path, the flow-limiting capillary 221, and the transfer tube 222. Furthermore, the sample injection splitting path is equipped with a drain branch 223, which is equipped with a one-way valve 224. Since the sample injection splitting path is connected to the flow-limiting capillary 221, which only allows a very small amount of sample to pass through, most of the sample is discharged through the drain branch 223, achieving the first splitting. The one-way valve 224 ensures that no external interference will enter from here. The sample flowing out of the flow-limiting capillary 221 enters, and since the transfer tube 222 is equipped with an extraction branch 225, which is connected to the vacuum generator, most of this part of the sample is extracted from the extraction branch 225, achieving the second splitting. Finally, a very small amount of the remaining sample enters the injection port of the mass spectrometer 4 for detection.

[0030] By setting up the venting branch 223 and the extraction branch 225, the sample is split twice, thereby achieving the pressure decay of the sample from positive pressure to mass spectrometry vacuum and completing mass spectrometry detection.

[0031] Preferably, the gas chromatograph 3 further includes a rapid chromatographic column 32 and a quantitative loop 33. The quantitative loop 33 is used to quantify the sample and send it into the rapid chromatographic column 32 for separation; The thermal conductivity detector 31 is located downstream of the rapid chromatographic column 32 and is connected to the splitting assembly 2.

[0032] The preferred gas chromatograph 3 also includes a rapid chromatographic column 32 and a quantitative loop 33. The rapid chromatographic column 32 is used for sample separation, while the quantitative loop 33 is used for volumetric quantification of the sample. A thermal conductivity detector 31 is located downstream of the rapid chromatographic column 32 and is connected to the split assembly 2. It utilizes the difference in thermal conductivity after the sample and carrier gas are mixed for non-destructive detection. The quantitative loop, chromatographic column, and thermal conductivity detector work together. The sample enters the quantitative loop, a quantitative volume is taken, and then sent to the chromatographic column for separation. Finally, it is quantified by the thermal conductivity detector.

[0033] Preferably, the gas chromatograph 3 further includes a six-way valve 34. The two lines of the six-way valve 34 are connected to the inlet and outlet of the quantitative loop 33, respectively, and the other four lines of the six-way valve 34 are connected to the carrier gas source, the sampling pump, the injection switching component 1, and the rapid chromatographic column 32, respectively; the sampling pump is used to deliver the sample into the quantitative loop 33. The carrier gas source is also connected to the thermal conductivity detector 31.

[0034] The gas chromatograph 3 further includes a six-way valve 34. Two lines of the six-way valve 34 are connected to the inlet and outlet of the quantitative loop 33, respectively. The other four lines of the six-way valve 34 are connected to the carrier gas source, the sampling pump, the injection switching assembly 1, and the rapid chromatographic column 32, respectively. The sampling pump is used to deliver the sample into the quantitative loop 33. The carrier gas source is also connected to the thermal conductivity detector 31. Whether in chromatographic quantitative detection mode or mass spectrometric quantitative detection mode, the quantitative loop 33 is used to quantify the initial sample to ensure the accuracy of the detection results.

[0035] Preferably, the gas chromatograph 3 includes multiple rapid chromatographic columns 32 connected in series.

[0036] When the composition of a substance is complex and a single rapid chromatography column 32 cannot achieve complete separation, multiple rapid chromatography columns 32 can be configured in series to adapt to various application scenarios.

[0037] Preferably, the gas chromatograph 3 is a gas chromatograph.

[0038] Preferably, the mass spectrometer 4 includes an ion source 41, a mass analyzer 42, and a detector 43. The sample inlet micropore of the ion source 41 is connected to the flow splitting component 2.

[0039] The preferred mass spectrometer 4 includes an ion source 41, a mass analyzer 42, and a detector 43, with the sample inlet micropore of the ion source 41 connected to the split assembly 2.

[0040] Based on the above specific structure, the detection modes of the multi-mode online detection system of this application are described as follows: First, single-mode mass spectrometry. Adjusting the switching valve 12 and the three-way valve 21 allows the sample to directly enter the mass spectrometer sample inlet split assembly 22 from the sample introduction component 11 for pressure regulation, and then enter the mass spectrometer 4 for detection. Within the mass spectrometer sample inlet split assembly 22, the sample is split twice, through the purging branch 223 and the extraction branch 225. A very small amount of the remaining sample enters the sample inlet micro-orifice of the ion source 41, where it is detected in conjunction with the mass analyzer 42 and the detector 43.

[0041] Second, the chromatographic separation-mass spectrometry qualitative and quantitative detection mode is particularly suitable for situations where the components of the sample to be analyzed are unclear, or where there is a need to detect unknown substances. Adjust the switching valve 12 so that the sample enters the gas chromatograph 3, is separated by the rapid chromatographic column 32, and then enters the mass spectrometer 4 for detection.

[0042] Third, the chromatographic separation-mass spectrometry qualitative-chromatographic quantitative mixed mode is suitable for applications requiring higher quantitative accuracy. Adjusting the switching valve 12 allows the sample to enter the gas chromatograph 3. Starting the sampling pump, in conjunction with the opening and closing of the corresponding tubing of the six-way valve 34, draws the sample into the quantitative loop 33. Then, switching the six-way valve 34 to the injection mode activates the carrier gas source. The carrier gas backflushs the sample gas in the quantitative loop 33 into the rapid chromatographic column 32. After separation by the rapid chromatographic column 32, the sample first passes through the thermal conductivity detector 31 (TCD) and is detected. At this stage, the detection only records retention time and signal intensity, without directly correlating with specific substance components. Since the detection by the thermal conductivity detector 31 is non-destructive, the sample gas continues to flow, passing through the three-way valve 21 into the mass spectrometry injection split assembly 22, and then into the mass spectrometer 4 for detection. Because chromatographic separation has been performed beforehand, each separated substance sequentially reaches mass spectrometer 4 for detection, resulting in a total ion current spectrum (TFCS). This TFCS and the chromatogram obtained from the thermal conductivity detector in the chromatography can establish a 1:1 relationship in retention time. The mass spectrometry data provides qualitative data for each detected substance, while the chromatogram provides quantitative data. Combining these two sets of data yields the qualitative and quantitative data for each component of the sample gas. Since qualitative analysis comes from mass spectrometry and quantification from chromatography, both accurate qualitative and quantitative results are achieved. The thermal conductivity detector is non-selective and universally applicable, suitable for detecting a wide variety of samples.

[0043] However, thermal conductivity detectors also have a drawback: their sensitivity is not high, and it is difficult to meet the sensitivity requirements for substances at the ppm level. Therefore, for samples with a wide concentration range, a fourth detection mode can be used: Fourth, the combined detection mode of chromatographic separation - high-concentration sample chromatographic detection - low-concentration sample mass spectrometry detection is suitable for situations where the components of the sample to be analyzed are clearly defined, but the concentration range is large, from percentage content to ppm or even ppb. Specifically, the switching valve 12 is adjusted to allow the sample to enter the gas chromatograph 3, the sampling pump is started, and the corresponding pipeline of the six-way valve 34 is opened and closed to draw the sample into the quantitative loop 33. Then, the six-way valve 34 is switched to the injection mode, the carrier gas source is started, and the carrier gas backflushes the sample gas in the quantitative loop 33 into the rapid chromatographic column 32. After separation by the rapid chromatographic column 32, the high-concentration sample gas first passes through the thermal conductivity detector 31 and is detected by it. Since the detection by the thermal conductivity detector 31 is a non-destructive detection, the sample gas continues to flow, enters the mass spectrometry injection split assembly 22 through the three-way valve 21, and then enters the mass spectrometer 4 for detection. At this time, the mass spectrometer 4 detects the low-abundance sample quantitative ions. In this way, by detecting high concentrations by chromatography and low concentrations by mass spectrometry, the quantitative accuracy and dynamic range can be further expanded, thereby broadening the application areas of the instrument.

[0044] The above description is merely an embodiment of this utility model. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this utility model, but these improvements all fall within the protection scope of this utility model.

Claims

1. A multi-mode online detection system, characterized in that, include: The sample injection switching unit (1), the splitting unit (2), the gas chromatograph (3) and the mass spectrometer (4); The sample injection switching assembly (1) is provided with an injection component (11) and a switching valve (12). The outlet of the injection component (11) is connected to the inlet of the switching valve (12) through a pipeline. The outlet of the switching valve (12) is connected to the split assembly (2) and the gas chromatograph (3) through pipelines respectively, and controls the sample to enter the split assembly (2) or the gas chromatograph (3). The downstream of the splitting component (2) is connected to the mass spectrometer (4), and the gas chromatograph (3) includes a thermal conductivity detector (31). The outlet of the thermal conductivity detector (31) is also connected to the splitting component (2) through a pipeline.

2. The multi-mode online detection system according to claim 1, characterized in that, The sample inlet component (11) is provided with multiple switchable sample inlet channels.

3. The multi-mode online detection system according to claim 1, characterized in that, The split assembly (2) includes a three-way valve (21) and a mass spectrometer injection split assembly (22); The three-way valve (21) is connected to the sample outlet of the gas chromatograph (3), the switching valve (12), and the mass spectrometer injection split assembly (22), respectively. The mass spectrometer sample splitter assembly (22) is used to split and depressurize the sample and deliver it to the mass spectrometer (4) for detection.

4. The multi-mode online detection system according to claim 3, characterized in that, The mass spectrometer sample injection split assembly (22) is connected in sequence to the sample injection split path, the flow-limiting capillary (221) and the transfer tube (222), and the outlet of the transfer tube (222) is connected to the sample inlet of the mass spectrometer (4). The sample injection splitting path is provided with an empty branch (223), and the empty branch (223) is provided with a one-way valve (224). The transmission tube (222) is provided with an extraction branch (225), which is connected to the vacuum generator.

5. The multi-mode online detection system according to claim 1, characterized in that, The gas chromatograph (3) also includes a rapid chromatographic column (32) and a quantitative loop (33). The quantitative loop (33) is used to quantify the sample and send it into the rapid chromatographic column (32) for separation; The thermal conductivity detector (31) is located downstream of the rapid chromatographic column (32) and is connected to the split assembly (2).

6. The multi-mode online detection system according to claim 5, characterized in that, The gas chromatograph (3) also includes a six-way valve (34). The two lines of the six-way valve (34) are connected to the inlet and outlet of the quantitative loop (33) respectively, and the other four lines of the six-way valve (34) are connected to the carrier gas source, the sampling pump, the injection switching assembly (1), and the rapid chromatographic column (32) respectively; the sampling pump is used to send the sample into the quantitative loop (33). The carrier gas source is also connected to the thermal conductivity detector (31).

7. The multi-mode online detection system according to any one of claims 5-6, characterized in that, The gas chromatograph (3) includes multiple fast chromatographic columns (32) connected in series.

8. The multi-mode online detection system according to claim 1, characterized in that, The mass spectrometer (4) includes an ion source (41), a mass analyzer (42), and a detector (43). The sample inlet of the ion source (41) is connected to the flow splitting assembly (2).

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