Trace gas inlet device and method suitable for front end of gas chromatograph

Abstract

The invention relates to the technical field of gas analysis, in particular to a trace gas inlet device and method suitable for the front end of a gas chromatograph, and the device comprises a sample tank assembly, a vacuum system, a cryogenic unit, a pulse flushing system, a flow path control assembly and a residual sample storage assembly; the sample tank assembly fixes a copper pipe containing trace gas through a copper pipe fixer, the vacuum system vacuumizes to eliminate interference, the cryogenic unit realizes complete gas release through low-temperature enrichment, the pulse flushing system cleans a pipeline, and the flow path control assembly accurately distributes the gas flow direction through a three-way diverter valve. And the residual sample storage assembly transfers residual gas to an external gas storage tank by using a micro sucking pump. The device realizes high-efficiency lossless sample injection of a trace closed gas sample, improves analysis precision and reliability, supports multiple recheck of the sample, can be seamlessly connected with an existing gas chromatograph, and has important practical value in exploration and analysis of strategic gas resources such as helium and natural hydrogen.

Description

Technical Field

[0001] This invention relates to the field of gas analysis technology, and in particular to a trace gas inlet device and method suitable for the front end of a gas chromatograph. Background Technology

[0002] Gas chromatography (GC), as the most common and widely recognized method for gas component analysis, plays a crucial role in many fields such as environmental monitoring, petrochemicals, biomedicine, and food safety. Current GC instruments are typically equipped with injection methods, such as manual or valve injection, which can adequately handle the injection of gas samples from containers like gas bags, cylinders, or saline bottles. However, these methods usually require a sample volume of at least 20 mL to ensure analytical accuracy and repeatability. In recent years, the significant increase in demand for emerging strategic energy resources such as helium and natural hydrogen has presented new challenges for the efficient analysis of these low-molecular-weight, volatile, trace-sized gas components. To ensure the airtightness and component stability of these gases during sampling and transport, copper tubing, which has low adsorption capacity, good sealing performance, and is easy to transport, is often used as a sampling and temporary storage container. However, existing GC injection systems are not designed to accommodate these trace, airtight sample containers, making direct injection impossible and severely limiting the ability to perform high-precision analysis of trace gas components in related fields. Therefore, there is an urgent need to develop a front-end device and method that can be seamlessly integrated with existing gas chromatography systems and is suitable for the injection of trace amounts of closed gas samples. This would not only meet the urgent need for high-precision gas composition analysis in the exploration and evaluation of emerging energy resources such as helium and natural hydrogen, but also effectively solve the long-standing problem of the difficulty in preserving and transporting such trace gas samples. This has important practical significance for improving analytical efficiency, data reliability, and the accuracy of resource evaluation. Summary of the Invention

[0003] The purpose of this invention is to provide a micro-gas inlet device and method suitable for the front end of a gas chromatograph, which can solve the above-mentioned technical problems.

[0004] This invention provides a micro-gas inlet device suitable for the front end of a gas chromatograph, comprising: A sample container assembly includes a sample container cavity, a sealing cap for sealing the sample container cavity, and a copper tube retainer disposed within the sample container cavity, the copper tube retainer being used to secure a copper tube containing a trace amount of gas. A vacuum system, which is connected to the sample container cavity, is used to evacuate the sample container cavity and related pipelines; A cryogenic unit includes a cold trap and a temperature controller. The cold trap is used to house the sample container assembly and cool the sample container cavity, and the temperature controller is used to control the cooling temperature. A pulse flushing system, which is connected to the outlet of the sample container cavity, is used to introduce a pulsed gas flow into the pipeline connected to the gas chromatograph for flushing. The flow path control component includes a three-way diverter valve, wherein the first port of the three-way diverter valve is connected to the outlet of the sample container, the second port is connected to the inlet of the gas chromatograph through an inlet connection tube, and the third port is connected to the residual sample sampling interface. And a residual sample preservation component, which includes a micro air pump connected to the residual sample sampling interface for transferring the residual gas to an external gas storage tank.

[0005] Preferably, the vacuum system includes a high-vacuum molecular pump, a vacuum valve, and a pressure sensor. The pressure sensor is used to monitor the pressure inside the sample container in real time, and a thermometer is provided on the sample container.

[0006] Preferably, the cryogenic unit is a liquid nitrogen cold trap, and the temperature controller has a temperature control accuracy of ±0.5℃; the inner wall of the liquid nitrogen cold trap is provided with an embedded temperature sensor.

[0007] Preferably, the pulse flushing system includes a programmable pulse meter, a gas source, and a pressure regulating valve. The programmable pulse meter is used to control the gas source to intermittently introduce gas into the pipeline at a set pulse frequency, pulse pressure, and pulse duration.

[0008] Preferably, the pulse frequency of the pulse flushing system is set to 1-5Hz, the pulse pressure is controlled at 0.2-0.8MPa, and the duration of a single pulse is 5-15s.

[0009] Preferably, the side wall of the sample container assembly is provided with a screw-in tube-breaking device, which includes a carbide spike for piercing the wall of the copper tube fixed to the copper tube holder.

[0010] Preferably, the device further includes a PLC control system, which is signal-connected to the vacuum system, cryogenic unit, pulse rinsing system, flow path control component and residual sample preservation component to achieve semi-automatic linkage control.

[0011] A method for introducing a small amount of gas using the device described above, characterized by comprising the following steps: S1: Fix the copper tube containing a trace amount of gas to the copper tube holder and place it into the sample container cavity. After sealing, start the vacuum system to evacuate the sample container cavity to a predetermined vacuum level. S2: The tube-breaking device is used to pierce the copper tube, the sample container assembly is placed in the cold trap and sealed, and the cryogenic unit is activated to cool the sample container cavity to the target temperature, so that the matrix components in the gas sample are liquefied and the trace components (gas) are enriched. S3: Switch the flow path control component to connect the sample chamber to the gas chromatograph inlet, start the pulse flushing system to perform pulse flushing on the sample inlet, and after flushing, introduce the gas sample into the gas chromatograph for analysis. S4: After the analysis is completed, switch the flow path control component to connect the sample chamber with the residual sample sampling interface, and start the residual sample preservation component to transfer the remaining gas in the sample chamber to the external gas storage tank for preservation.

[0012] Preferably, the predetermined vacuum degree is 10. -2 Pa or less; in step S2, the spiral advance rate of the tube breaking device is not greater than 1 mm / s.

[0013] Preferably, in step S3, the number of pulse flushing cycles is 3-8 times, and the pulse interval is 5 seconds; in step S4, before transferring the remaining gas, the sample container cavity is heated to room temperature to completely vaporize the liquefied gas.

[0014] Beneficial effects: The gas chromatography front-end trace gas inlet device provided by this invention, through its integrated modular design, achieves efficient and non-destructive injection of trace gas samples, such as those from sealed copper tubes, significantly improving analytical accuracy and operational reliability. First, a dedicated sample container assembly directly fixes and introduces the trace copper tube sample, overcoming the technical bottleneck of traditional injection methods being incompatible with trace sealed containers. Second, the vacuum system, in conjunction with the cryogenic unit, achieves efficient and complete release of trace gases through low-temperature enrichment while completely eliminating air interference, greatly improving detection sensitivity and accuracy. Furthermore, the pulse flushing system and flow path control assembly ensure pipeline cleanliness and precise control of the injection volume, while the residual sample preservation assembly safely transfers and stores valuable samples, enabling multiple uses and re-analysis of the samples. The entire device seamlessly integrates with existing gas chromatographs, not only expanding the instrument's analytical capabilities for trace gases from strategic resources such as helium and natural hydrogen, but also effectively solving the stability problems of such samples during preservation and transportation, possessing significant practical value for improving the data reliability and analytical efficiency of resource exploration and evaluation. Attached Figure Description

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

[0016] Figure 1 This is a schematic diagram of the sample container cavity and its internal structure in this invention; Figure 2This is a schematic diagram of the sample container cavity in its working state according to the present invention.

[0017] Explanation of reference numerals in the attached diagram: 1-Sample container cavity, 2-Sealing cap, 3-Copper tube holder, 4-Polymer vacuum pump, 5-Liquid nitrogen cold trap, 6-Three-way diverter valve, 7-Pulse meter, 8-Swivel tube breaking device, 9-Miniature diaphragm vacuum pump, 10-Gas chromatograph, 11-Residual sample sampling interface, 12-Temperature controller, 13-Copper tube, 14-Pressure sensor, 15-Thermometer, 16-Gas outlet, 17-Temperature sensor, 18-Sealing interface. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Example 1 This embodiment provides a trace gas inlet device suitable for the front end of a gas chromatograph. This device, as an independent module, is connected to the gas chromatograph's inlet via an inlet connector. Its core purpose is to achieve automated, high-precision processing and introduction of trace gas samples, and it specifically includes the following components: 1. Sample container assembly The sample container assembly is the core of the device, used for the safe loading and release of trace gas samples. It includes a cylindrical sample container chamber 1 with a removable sealing cap 2 at one end, which achieves a high-vacuum seal via a sealing ring. A copper tube retainer 3 is located at the center of the bottom of the chamber. This retainer has a groove that matches a standard-sized copper tube, which can securely and vertically fix the sealed copper tube 13 containing the trace gas to be measured (such as for storing standard gas or sampling gas).

[0022] A screw-in tube-breaking device 8 is installed on the side wall of the sample container assembly. This device includes a manually operated handle, a precision threaded drive mechanism, and a sharp needle made of hard alloy. By rotating the handle clockwise, the needle can be smoothly and precisely advanced forward under threaded guidance until it pierces the copper tube wall fixed to the copper tube holder, thereby releasing the internal gas. A high-precision thermometer 15 is also installed on the sample container cavity 1 for direct monitoring of the cavity temperature.

[0023] 2. Vacuum system A vacuum system is used to create a clean, low-pressure environment before sample injection. This system is connected to the sample container cavity via a vacuum tubing. A vacuum valve, pressure sensor 14, and a high-vacuum molecular pump 4 are connected in series on the tubing. The pressure sensor (such as a capacitive thin-film gauge) is used to monitor the pressure in the sample container cavity and connecting tubing in real time and accurately, and feeds the signal back to the control system. The high-vacuum molecular pump can evacuate the system to a vacuum level of 10. -2 Below Pa, it effectively removes residual air and volatile pollutants. All vacuum lines and valves are made of passivated 316L stainless steel to reduce adsorption on the inner walls.

[0024] 3. Cryogenic Unit The cryogenic unit is used to cool the sample container assembly, achieving cryogenic enrichment of the gas and thus increasing the sample concentration entering the gas chromatograph. In this embodiment, the cryogenic unit uses a liquid nitrogen Dewar flask as the cold source, and the liquid nitrogen cold trap 5 is a metal (such as copper or aluminum) cavity that matches the shape of the sample container cavity. The sample container assembly can be placed entirely into this cold trap. The temperature controller 12 is connected to the heating wire and liquid nitrogen injection solenoid valve embedded in the cold trap, forming a closed-loop control. At the same time, an embedded temperature sensor 17 is provided on the inner wall of the liquid nitrogen cold trap, and its signal is used as an auxiliary feedback input to the temperature controller. The controller has a temperature control accuracy of ±0.5℃ and can stably control the temperature of the sample container cavity within any set value between the liquid nitrogen temperature (-196℃) and room temperature, for example, -180℃ for deep trapping of volatile gases.

[0025] 4. Pulse flushing system The pulse flushing system is connected downstream of the sample container's outlet. After sample release, it uses pulsed carrier gas to efficiently flush the flow path from the connecting tubing to the gas chromatograph's injection valve, ensuring complete and rapid sample transfer and eliminating the "memory effect." The system includes a high-pressure gas source (such as a high-purity helium cylinder), a pressure regulating valve, a high-speed solenoid valve, and a programmable pulse generator. The programmable pulse generator receives commands from the control system and drives the high-speed solenoid valve to intermittently introduce flushing gas into the tubing at a set pulse frequency. This pulsed gas flow generates turbulence, providing superior tubing cleaning and sample carrying capacity compared to a continuous, stable gas flow.

[0026] 5. Flow path control components The flow path control assembly guides the airflow direction. At its core is a high-performance three-way diverter valve 6 (e.g., electromagnetically or pneumatically driven). The valve's first port (normally closed) is directly connected via tubing to the top outlet 16 of the sample container 1. The second port is connected to the gas chromatograph 10's inlet via a short, inert injection tube (e.g., a fused silica capillary). The third port is connected to a residual sample sampling interface 11.

[0027] 6. Sample Saving Component The residual sample preservation component is used to recover the gas sample remaining after chromatographic injection. It includes a miniature diaphragm pump 9, whose inlet is connected via tubing to the residual sample sampling interface 11 on the aforementioned flow path control component. The pump outlet is connected to a quick-connect external gas storage tank (e.g., a sampling bag with a valve or a small stainless steel gas cylinder). When residual sample preservation is required, the pump is activated to transfer any remaining uninjected gas in the tubing and sample container to the external gas storage tank.

[0028] 7. Control System The entire apparatus is semi-automatically controlled by a PLC (Programmable Logic Controller) system. The PLC connects via communication interfaces (such as RS485 or Ethernet) to all electrical components, including the pressure sensors and molecular pump controller of the vacuum system, the temperature controller of the cryogenic unit, the programmable pulse meter of the pulse flushing system, the three-way diverter valve in the flow path control assembly, and the miniature pump in the sample preservation assembly. Operators can set experimental parameters (such as vacuuming time, cold trap temperature, and pulse flushing program) and initiate the automatic operation sequence with a single button press through a human-machine interface (touchscreen) connected to the PLC.

[0029] The specific implementation steps are as follows: Step S01: Insert the copper tube and evacuate the sample container cavity. This step aims to establish an initial vacuum environment, eliminate interference from residual gas in the pipeline, and lay the foundation for subsequent gas sample introduction and liquefaction. The operational details are as follows: (1) Insertion and fixation of copper tube: Unscrew the sealing threaded cap on the top of the sample container and take out the built-in three-jaw elastic copper tube holder; put the copper tube to be tested (volume 10-50mL, clean outer wall without oil stains) into the center slot of the holder, adjust the distance between the claws to fix the copper tube coaxially, and then put the holder together with the copper tube into the sample container.

[0030] (2) Vacuum system startup and pressure monitoring: Tighten the threaded cap to ensure a tight seal between the cap and the sample container cavity; turn on the high-vacuum molecular pump and activate the pressure sensor to monitor the cavity pressure in real time. During the vacuuming process, if the pressure drops to 10... -2 If the pressure is below 1 Pa and remains stable for 5 minutes without fluctuation (eliminating the risk of leakage), the vacuum level is considered to be up to standard. If the pressure drops slowly or rebounds, the vacuum pump should be turned off to check the sealing of the threaded cap and the pipe joints. After eliminating the risk of leakage, the vacuum should be re-evacuated.

[0031] (3) Vacuum system shutdown: After confirming that the vacuum level meets the standard, turn off the vacuum molecular pump. At this time, the sample container cavity remains in a closed vacuum state, waiting for subsequent gas sample introduction.

[0032] Step S02: Puncture the copper tube and place the sample container into the cold trap. (1) Copper tube puncture and gas sample release: Operate the spiral tube puncture device (the spike material is hard alloy, and the tip diameter is 0.5 mm) on the side wall of the sample container cavity, and slowly spiral the spike (the spiraling speed is ≤1 mm / s to avoid the gas impact causing a sudden pressure rise) until the spike penetrates the copper tube wall (it can be judged by the change in resistance by hand; the resistance suddenly decreases when penetrating); after stopping the spiraling, keep the spike in position for 30 seconds to allow the gas sample in the copper tube to be fully released into the sample container cavity. At this time, the pressure sensor monitors the pressure in the cavity to rise back to a stable value (the specific value depends on the amount of gas sample in the copper tube) to confirm that the gas sample has been completely released.

[0033] (2) Sample container cavity and cold trap docking and sealing: Vertically place the sample container cavity (with handle design) into the liquid nitrogen cold trap, ensuring that the gap between the outer wall of the sample container cavity and the inner wall of the cold trap is uniform (about 5 mm, to ensure uniform transfer of cold energy); cover the cold trap with the cover, so that the metal sealing interface 18 on the cover is precisely docked with the self-sealing gas outlet 16 on the top of the sample container cavity. When docking, rotate the cold trap cover clockwise 3 times until you hear a "click" sound (locking mechanism is in place). At this time, the one-way valve of the self-sealing gas outlet opens and the gas path is open; if it is not docked or not docked properly, the self-sealing gas outlet remains closed to ensure that the gas sample in the cavity does not leak. During this process, the three-way diverter valve must be kept in the "closed" state to prevent the gas sample from entering the subsequent pipeline in advance.

[0034] (3) Cryogenic liquefaction and state judgment: The target temperature of the cold trap is set by the temperature controller (adjusted according to the matrix composition of the gas sample, for example, -150℃ when detecting VOCs), and the liquid nitrogen supply system is started (liquid nitrogen flow rate 50mL / min). The temperature in the cold trap gradually drops to the target value. The temperature sensor in the sample container cavity provides real-time temperature data. When the temperature stabilizes at the target temperature (fluctuation ±0.5℃) for 10 minutes, and the pressure sensor detects that the pressure drop rate in the cavity is ≤0.1Pa / min, it is determined that most of the matrix gas (such as hydrocarbon gas, oxygen, etc.) has been liquefied (liquefaction rate ≥95%), and the trace components to be measured are separated from the matrix gas, thus completing the cryogenic concentration pretreatment.

[0035] Step S03: Pulse flush the pipeline and test gas components or isotopes. (1) Flow path switching: After confirming that cryogenic liquefaction is completed, switch the three-way diverter valve from the "closed" state to the "sample inlet connection tube" path (connecting the sample tank cavity and the gas chromatograph inlet) through the PLC control system. (2) Pulse flushing of the pipeline: Turn on the pulse meter and the carrier gas cylinder (sample gas flushing or carrier gas flushing can be selected according to the situation), set the pulse parameters (adjust according to the pipeline material), and start the pulse flushing program. High-pressure carrier gas enters the injection pipeline in an intermittent pulse form. The instantaneous impact force penetrates the dead volume of the pipeline and removes residual impurities from the inner wall. After each pulse, there is a 5-second interval (briefly let it stand to allow residual gas to diffuse) before the next pulse is performed. During the flushing process, the response of the target component in the gas chromatograph can be used to help judge the cleaning effect. When the response value of the target component is lower than the detection limit, it indicates that the pipeline has been cleaned to the standard.

[0036] (3) Pulse termination and formal sample injection: After completing the set number of pulse flushes, the pulse instrument automatically shuts down; the gas sample injection volume is controlled by the flow meter, and the solenoid valve between the sample canister and the injection port is opened, allowing the gas sample to enter the gas chromatograph at a stable flow rate (10-20 mL / min). The chromatograph detection program is started to complete the analysis of gas component content or isotope ratio, and the detection data is transmitted to the data processing system in real time.

[0037] To further ensure the stability of the gas inlet, this step is added when performing step S03(3): Concentrated sample (trace component to be measured) transfer: The transfer system is connected between the sample container and the gas chromatograph, including a vacuum pump, an enrichment bottle, and a high-precision pressure sensor installed on the enrichment bottle. The volume of the enrichment bottle is adjustable and is installed on the injection connection tube between the three-way split valve and the gas chromatograph. The inlet and outlet of the enrichment bottle are equipped with inlet valves and outlet valves, respectively. First, the vacuum pump is used to evacuate the enrichment bottle to the preset target vacuum level. After the target vacuum level is reached, the inlet valve of the enrichment bottle is opened, and the gas to be measured after cryogenic concentration pretreatment is drawn into the enrichment bottle using the vacuum pump. The pressure change inside the enrichment bottle is monitored in real time by the high-precision pressure sensor. According to the monitored pressure data, the volume of the enrichment bottle is manually adjusted to adjust the pressure inside the bottle so that it meets the pressure requirements for chromatographic injection. After the gas to be tested comes out of the three-way diverter valve, it first enters the enrichment bottle (which acts as a buffer tank). After the pressure is adjusted in the enrichment bottle, the outlet valve is opened and the gas is sent into the gas chromatograph.

[0038] Step S04: Transfer of remaining samples (1) Sample container preparation and connection: Select a suitable gas storage tank and check whether its sealing interface (quick connector that matches the residual sample sampling interface) is clean and free of impurities; connect the sample storage container to the residual sample sampling interface through the quick connector to ensure that it is sealed and leak-free.

[0039] (2) Flow path switching and transfer method selection: Switch the flow path from "sample inlet connection tube" to "residual sample sampling interface" through the three-way diverter valve. At this time, the sample container cavity and the sample storage container are connected. Select the transfer method according to the requirements: Method 1: Flash vapor transfer (suitable for scenarios where only a small amount of gas sample needs to be stored): Keep the sample container in a cold trap environment, start the micro vacuum pump, and use negative pressure to draw the flash vapor in the sample container into the storage container.

[0040] Method 2: Transfer all remaining gases (applicable to scenarios where complete preservation of remaining samples is required): Turn off the liquid nitrogen supply system of the cold trap, remove the sample container from the cold trap, place it in a room temperature environment (25°C), and allow it to heat up naturally to completely vaporize the liquefied matrix gas inside the container (confirm that the temperature inside the container has reached room temperature and the pressure is stable by using a temperature sensor); cover the sample container with the cold trap cover and complete the sealing docking (same as step S02 (2)), turn on the micro vacuum pump, and draw all the gas inside the container into the sample storage container.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A micro-gas inlet device suitable for the front end of a gas chromatograph, characterized in that, include: A sample container assembly includes a sample container cavity, a sealing cap for sealing the sample container cavity, and a copper tube retainer disposed within the sample container cavity, the copper tube retainer being used to secure a copper tube containing a trace amount of gas. A vacuum system, which is connected to the sample container cavity, is used to evacuate the sample container cavity and related pipelines; A cryogenic unit includes a cold trap and a temperature controller. The cold trap is used to house the sample container assembly and cool the sample container cavity, and the temperature controller is used to control the cooling temperature. A pulse flushing system, which is connected to the outlet of the sample container cavity, is used to introduce a pulsed gas flow into the pipeline connected to the gas chromatograph for flushing. The flow path control component includes a three-way diverter valve, wherein the first port of the three-way diverter valve is connected to the outlet of the sample container, the second port is connected to the inlet of the gas chromatograph through an inlet connection tube, and the third port is connected to the residual sample sampling interface. And a residual sample preservation component, which includes a micro air pump connected to the residual sample sampling interface for transferring the residual gas to an external gas storage tank.

2. The micro-gas inlet device for the front end of a gas chromatograph according to claim 1, characterized in that, The vacuum system includes a high-vacuum molecular pump, a vacuum valve, and a pressure sensor, the pressure sensor being used to monitor the pressure inside the sample container in real time.

3. The micro-gas inlet device for the front end of a gas chromatograph according to claim 1, characterized in that, The cryogenic unit is a liquid nitrogen cold trap, and the temperature control accuracy of the temperature controller is ±0.5℃; the inner wall of the liquid nitrogen cold trap is equipped with an embedded temperature sensor.

4. The micro-gas inlet device for the front end of a gas chromatograph according to claim 1, characterized in that, The pulse flushing system includes a programmable pulse meter, a gas source, and a pressure regulating valve. The programmable pulse meter is used to control the gas source to intermittently introduce gas into the pipeline at a set pulse frequency, pulse pressure, and pulse duration.

5. The micro-gas inlet device for the front end of a gas chromatograph according to claim 1, characterized in that, The pulse frequency of the pulse flushing system is set to 1-5Hz, the pulse pressure is controlled at 0.2-0.8MPa, and the duration of a single pulse is 5-15s.

6. The micro-gas inlet device for the front end of a gas chromatograph according to claim 1, characterized in that, The sample container assembly is provided with a spiral tube-breaking device on its side wall. The tube-breaking device includes a hard alloy spike for piercing the wall of the copper tube fixed to the copper tube holder.

7. The micro-gas inlet device for the front end of a gas chromatograph according to claim 1, characterized in that, The device also includes a PLC control system, which is connected to the vacuum system, cryogenic unit, pulse rinsing system, flow path control component and residual sample preservation component for semi-automatic linkage control.

8. A method for introducing a trace amount of gas using the apparatus as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Fix the copper tube containing a trace amount of gas to the copper tube holder and place it into the sample container cavity. After sealing, start the vacuum system to evacuate the sample container cavity to a predetermined vacuum level. S2: The tube breaking device is used to puncture the copper tube, the sample container assembly is placed in the cold trap and sealed, and the cryogenic unit is activated to cool the sample container cavity to the target temperature, so that the matrix components in the gas sample are liquefied and trace components are enriched. S3: Switch the flow path control component to connect the sample chamber to the gas chromatograph inlet, start the pulse flushing system to perform pulse flushing on the sample inlet, and after flushing, introduce the gas sample into the gas chromatograph for analysis. S4: After the analysis is completed, switch the flow path control component to connect the sample chamber with the residual sample sampling interface, and start the residual sample preservation component to transfer the remaining gas in the sample chamber to the external gas storage tank for preservation.

9. The method according to claim 8, characterized in that, The predetermined vacuum level is 10. -2 Pa or less; in step S2, the spiral advance rate of the tube breaking device is not greater than 1 mm / s.

10. The method according to claim 8, characterized in that, In step S3, the pulse flushing cycle is 3-8 times, with a pulse interval of 5 seconds; in step S4, before transferring the remaining gas, the sample container is heated to room temperature to completely vaporize the liquefied gas.

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