Device and method for combined testing of nitrogen and noble gas isotopes in trace samples

Abstract

The present invention discloses a device and method for the joint testing of nitrogen and noble gas isotopes in a trace sample. The device comprises a laser sample tray, a vacuum system, a CuO furnace, an air standard, a CT quartz cold trap, an ion pump, a first getter, a second getter, an activated carbon stainless steel cold trap, and a noble gas mass spectrometer. The device utilizes laser heating to release nitrogen and noble gases in the sample, and then controls the internal volume to divide the generated gas into two parts according to a certain ratio, thereby obtaining nitrogen and noble gas samples respectively. The device can simultaneously analyze nitrogen isotopes and noble gas isotopes in a sample using one sample, thereby saving sample usage and ensuring sample consistency.

Description

Technical Field

[0001] The present invention relates to the technical field of isotope detection, and in particular to a device and method for joint testing of trace sample nitrogen and noble gas isotopes. Background Art

[0002] Extraterrestrial samples, whether from the recently returned Chang'e 5 samples or meteorites, are extremely valuable. However, conventional nitrogen isotope analysis methods rely on dynamic analysis using stable isotope mass spectrometry. This method requires large sample volumes and cannot analyze noble gases. If a separate sample is prepared for noble gas isotope analysis, sample consumption is high and there is no way to guarantee consistency between the two samples. Summary of the Invention

[0003] The purpose of the present invention is to provide a device and method for the joint testing of nitrogen and noble gas isotopes in trace samples to solve the problems existing in the above-mentioned prior art. The device and method can use a single sample to simultaneously analyze nitrogen isotopes and noble gas isotopes in the sample, thereby saving sample usage and ensuring sample consistency.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a device for the combined testing of trace sample nitrogen and noble gas isotopes, comprising a laser sample tray, a vacuum system, a CuO furnace, an air standard sample, a CT quartz cold trap, an ion pump, a first getter, a second getter, an activated carbon stainless steel cold trap, and a noble gas mass spectrometer; wherein the laser sample tray is connected to the noble gas mass spectrometer via a main pipe, and the vacuum system, the CuO furnace, the air standard sample, the CT quartz cold trap, the ion pump, the getter, and the activated carbon stainless steel cold trap are sequentially connected to the main pipe from the head end to the tail end; a first valve is provided on the main pipe at the outlet of the laser sample tray, a second valve is provided between the vacuum system and the main pipe, and a valve is provided between the CuO furnace and the main pipe. A valve three is provided, a valve four and a valve five are provided between the air standard sample and the main line, a valve six is provided between the air standard sample and the getter one, a valve seven is provided between the getter one and the main line, a valve eight is provided on the main line between the getter one and the getter two, a valve nine is provided between the getter two and the main line, a valve ten is provided on the main line between the CT quartz cold trap and the ion pump, a valve eleven is provided between the ion pump and the main line, a valve twelve is provided between the activated carbon stainless steel cold trap and the main line, and a valve thirteen is provided on the main line at the entrance of the rare gas mass spectrometer.

[0006] Preferably, a diamond sample window is provided above the laser sample disk, and the infrared laser can heat or even melt the sample through the sample window.

[0007] Preferably, the vacuum system is a double-stage vacuum structure of dry pump plus molecular pump, which can pump the air pressure of the pipeline to 1*10 -6 Below Pa.

[0008] Preferably, the CuO furnace is a quartz tube with a CF16 metal interface, 2-5 g of CuO powder is arranged in the quartz tube, and a muffle furnace is arranged on the outer shell of the quartz tube, and the muffle furnace can heat the quartz tube to 1000°C.

[0009] Preferably, a quantitative pipeline is provided between the valve four and the valve five.

[0010] Preferably, the getter one and the getter two are both ST101 getter materials, a heating wire is provided inside the ST101 getter material, and the getter one and the getter two are externally connected to the main pipe through valve seven and valve nine respectively via CF16 flanges.

[0011] Preferably, the CT quartz cold trap is a quartz tube with a CF16 metal interface, and the outer surface of the quartz tube is provided with a thermos cup filled with liquid nitrogen for adsorbing chemically generated CO2 gas.

[0012] Preferably, the activated carbon stainless steel trap is a stainless steel tube with a CF16 metal interface, and the stainless steel tube is sheathed with a thermos cup filled with liquid nitrogen for adsorbing argon.

[0013] Based on the above-mentioned device for combined testing of trace sample nitrogen and noble gas isotopes, the present invention also provides a method for combined testing of trace sample nitrogen and noble gas isotopes, which includes two processes: sample analysis and air analysis calibration;

[0014] Sample analysis includes the following steps:

[0015] 1) Open valve 1, valve 2, valve 3, valve 6, valve 7, valve 8, valve 9, valve 10, and valve 12, and keep the other valves closed. Use the vacuum system to evacuate the entire pipeline;

[0016] 2) Close valve 1 and use laser to heat the sample to be analyzed;

[0017] 3) Close valve 2 and valve 6, open valve 1 to allow the heated gas sample to diffuse freely into the CuO furnace, and close valve 3;

[0018] 4) Open valve 6 and allow the remaining gas to diffuse freely into the main line. Getter 1 and adsorbent 2 adsorb the active gas in the main line. Then, liquid nitrogen is used to cool the activated carbon stainless steel cold trap to adsorb the argon gas. At the same time, the CuO furnace is heated using a muffle furnace.

[0019] 5) First, analyze the rare gases. While the CuO furnace temperature is maintained, close valve 1 and open valve 13. Use a rare gas mass spectrometer to analyze the He and Ne gases that are not adsorbed by the activated carbon stainless steel cold trap.

[0020] 6) After the analysis of He and Ne gases is completed, valve 11 is opened to extract the analyzed gases, valve 11 is closed and valve 12 is opened to return the activated carbon stainless steel cold trap to room temperature to release the originally adsorbed Ar, and then valve 13 is opened for analysis;

[0021] 7) After the analysis is completed, open valve 11 to remove the analyzed gas, close valves 11, 7, 8, and 12, and open valve 3 to allow the CuO gas sample to diffuse freely into the CT quartz trap. Use liquid nitrogen to cool the CT quartz trap so that the inner wall of the CT quartz trap can adsorb the CO2 generated by the reaction with CuO.

[0022] 8) Open valve 13 to allow the remaining adsorbed gas to diffuse freely into the noble gas mass spectrometer for N isotope analysis until the measurement is completed;

[0023] Air analysis includes the following steps:

[0024] 1) Open valves 1, 2, 3, 6, 7, 8, 9, 10, and 12, and keep the other valves closed. Use the vacuum system to evacuate the entire pipeline.

[0025] 2) Open valve 4 and allow the gas to diffuse freely into the quantitative pipeline between valves 4 and 5;

[0026] 3) Close valve 1 and valve 4, open valve 5, allow the gas to diffuse freely into the CuO furnace, and close valve 3;

[0027] 4) Open valve 6 and allow the remaining gas to diffuse freely into the main line. Use getter 1 and getter 2 to adsorb the active gas in the main line. Then use liquid nitrogen to cool the activated carbon stainless steel cold trap to adsorb the argon gas. At the same time, use a muffle furnace to heat the CuO furnace.

[0028] 5) First, analyze the rare gases. While the CuO furnace temperature is maintained, close valve 12 and open valve 13. Use a rare gas mass spectrometer to analyze the He and Ne gases that are not adsorbed by the activated carbon stainless steel cold trap.

[0029] 6) After the analysis of He and Ne gases is completed, valve 11 is opened to remove the analyzed gases, valve 11 is closed, valve 12 is opened to restore the activated carbon stainless steel cold trap to room temperature to release the originally adsorbed Ar, and then valve 13 is opened to continue analysis;

[0030] 7) After the analysis is completed, open valve 11 to remove the analyzed gas, close valves 11, 7, 8, and 12, and open valve 3 to allow the CuO gas sample to diffuse freely into the CT quartz trap. Use liquid nitrogen to cool the CT quartz trap so that the inner wall of the CT quartz trap can adsorb the CO2 generated by the reaction with CuO.

[0031] 8) Open valve 13 to allow the remaining adsorbed gas to diffuse freely into the noble gas mass spectrometer for N isotope analysis until the measurement is completed.

[0032] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0033] The present invention provides an apparatus and method for the combined testing of nitrogen and noble gas isotopes in trace samples. The apparatus and method utilize laser heating to release nitrogen and noble gases in the sample. The internal volume is then controlled to divide the generated gas into two parts according to a certain ratio. One part is purified by a CuO furnace to convert CO and C, H compounds into CO2 and H2O. The above substances are then adsorbed by a quartz liquid nitrogen cold trap to obtain relatively pure nitrogen. The nitrogen isotopes are analyzed by a noble gas mass spectrometer to obtain the N isotope composition of the sample. The other part is purified by a CuO furnace to convert CO and C, H compounds into CO2 and H2O. A gas sample is purified by a getter to remove active gases therein, and then a stainless steel liquid nitrogen cold trap with activated carbon is used to adsorb the Ar, Kr, and Xe rare gases therein. The remaining He and Ne in the pipeline are first measured by a rare gas mass spectrometer. After the pipeline is evacuated, the stainless steel liquid nitrogen cold trap with activated carbon is heated and released in sequence to release Ar gas, Kr gas, and Xe gas, and they are measured one by one in the rare gas mass spectrometer. The present invention can use one sample to simultaneously analyze nitrogen isotopes and rare gas isotopes in the sample, save sample usage, and ensure sample consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the structure of the device for combined testing of trace sample nitrogen and noble gas isotopes in the present invention;

[0036] In the figure: 1-laser sample tray, 2-vacuum system, 3-CuO furnace, 4-air standard, 5-CT quartz cold trap, 6-ion pump, 7-getter 1, 8-getter 2, 9-activated carbon stainless steel cold trap, 10-rare gas mass spectrometer, 11-valve 1, 12-valve 2, 13-valve 3, 14-valve 4, 15-valve 5, 16-valve 6, 17-valve 7, 18-valve 8, 19-valve 9, 20-valve 10, 21-valve 11, 22-valve 12, 23-valve 13. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] The purpose of the present invention is to provide a device and method for the joint testing of trace sample nitrogen and noble gas isotopes, so as to solve the problems existing in the prior art.

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] The device for combined testing of trace sample nitrogen and noble gas isotopes in this embodiment is as follows: Figure 1As shown, it includes a laser sample tray 1, a vacuum system 2, a CuO furnace 3, an air standard 4, a CT quartz cold trap 5, an ion pump 6, a getter 1 7, a getter 2 8, an activated carbon stainless steel cold trap 9 and a rare gas mass spectrometer 10; wherein the laser sample tray 1 is connected to the rare gas mass spectrometer 10 through a main pipe, and the vacuum system 2, the CuO furnace 3, the air standard 4, the CT quartz cold trap 5, the ion pump 6, the getter and the activated carbon stainless steel cold trap 9 are sequentially connected to the main pipe from the head end to the tail end; a valve 11 is provided on the main pipe at the outlet of the laser sample tray 1, a valve 2 12 is provided between the vacuum system 2 and the main pipe, and a valve 13 is provided between the CuO furnace 3 and the main pipe. Door three 13, valve four 14 and valve five 15 are provided between the air standard sample 4 and the main line, valve six 16 is provided between the air standard sample 4 and getter one 7, valve seven 17 is provided between getter one 7 and the main line, valve eight 18 is provided on the main line between getter one 7 and getter two 8, valve nine 19 is provided between getter two 8 and the main line, valve ten 20 is provided on the main line between the CT quartz cold trap 5 and the ion pump 6, valve eleven 21 is provided between the ion pump 6 and the main line, valve twelve 22 is provided between the activated carbon stainless steel cold trap 9 and the main line, and valve thirteen 23 is provided on the main line at the entrance of the rare gas mass spectrometer 10.

[0041] In this specific embodiment, a diamond sample window connected via a CF35 flange is provided above the laser sample disk 1 , and the infrared laser can heat or even melt the sample through the sample window.

[0042] In this specific embodiment, the vacuum system 2 is a two-stage vacuum structure of a dry pump plus a molecular pump, which can pump the air pressure of the pipeline to below 1*10-6Pa.

[0043] In this specific embodiment, the CuO furnace 3 is a quartz tube with a CF16 metal interface. 2-5g of CuO powder is set in the quartz tube. A muffle furnace is arranged outside the quartz tube. The muffle furnace can heat the quartz tube to 1000°C.

[0044] In this specific embodiment, a quantitative pipeline is provided between valve four 14 and valve five 15.

[0045] In this specific embodiment, the getter 1 7 and the getter 2 8 are both ST101 getter materials, and a heating wire is provided inside the ST101 getter material. The outsides of the getter 1 7 and the getter 2 8 are connected to the main pipe through the CF16 flange through the valve 7 17 and the valve 9 19 respectively.

[0046] In this specific embodiment, the CT quartz cold trap 5 is a quartz tube with a CF16 metal interface. A thermos cup filled with liquid nitrogen is sheathed outside the quartz tube for adsorbing chemically generated CO2 gas.

[0047] In this specific embodiment, the activated carbon stainless steel trap is a stainless steel tube with a CF16 metal interface. A thermos cup filled with liquid nitrogen is sheathed outside the stainless steel tube for adsorbing argon.

[0048] Based on the above-mentioned device for combined testing of trace sample nitrogen and noble gas isotopes, the present invention also provides a method for combined testing of trace sample nitrogen and noble gas isotopes, which includes two processes: sample analysis and air analysis calibration.

[0049] Sample analysis includes the following steps:

[0050] 1) Open valve 1 11, valve 2 12, valve 3 13, valve 6 16, valve 7 17, valve 8 18, valve 9 19, valve 10 20, and valve 12 22, while keeping the other valves closed. Use vacuum system 2 to evacuate the entire pipeline.

[0051] 2) Close valve 11 and use laser to heat the sample to be analyzed;

[0052] 3) Close valve two 12 and valve six 16, open valve one 11 to allow the gas sample released by heating to diffuse freely into the CuO furnace 3, and close valve three 13;

[0053] 4) Open valve six 16 and allow the remaining gas to diffuse freely into the main line. The active gas in the main line is adsorbed by getter one 7 and adsorbent two. To ensure the adsorption effect, this process needs to be maintained for 20 minutes. Then, the activated carbon cold trap is cooled with liquid nitrogen for 10 minutes to adsorb the argon gas therein. At the same time, the CuO furnace 3 is heated in a muffle furnace. First, it is heated to 850°C and maintained for 15 minutes. Then, the temperature is reduced to 600°C and maintained for 15 minutes. Finally, it is reduced to 450°C and maintained for 15 minutes.

[0054] 5) Because the noble gas purification time is short, the noble gases are analyzed first. While the temperature of the CuO furnace 3 is maintained, valve 11 is closed, valve 13 23 is opened, and the He and Ne gases not adsorbed by the activated carbon stainless steel cold trap 9 are analyzed using a noble gas mass spectrometer 10;

[0055] 6) After the analysis of He and Ne gases is completed, valve 11 21 is opened to extract the analyzed gases, valve 11 21 is closed, valve 12 22 is opened, the activated carbon stainless steel cold trap 9 is restored to room temperature to release the originally adsorbed Ar, and then valve 13 23 is opened for analysis;

[0056] 7) After the analysis is completed, valve 11 21 is opened to remove the analyzed gas. Valve 11 21, valve 7 17, valve 8 18, and valve 12 22 are closed. Valve 3 13 is opened to allow the CuO gas sample to diffuse freely into the CT quartz trap. Liquid nitrogen is used to cool the CT quartz trap. The inner wall of the CT quartz trap can adsorb the CO2 generated by the reaction with CuO. To ensure the effectiveness of the adsorption, the adsorption time needs to be maintained for 20 minutes.

[0057] 8) Open valve 13 23 to allow the remaining adsorbed gas (mainly nitrogen) to diffuse freely into the noble gas mass spectrometer 10 for N isotope analysis until the measurement is completed;

[0058] Air analysis includes the following steps:

[0059] 1) Open valve 1 11, valve 2 12, valve 3 13, valve 6 16, valve 7 17, valve 8 18, valve 9 19, valve 10 20 and valve 12 22, and keep the other valves closed. Use vacuum system 2 to evacuate the entire pipeline.

[0060] 2) Open valve 4 14, and the gas freely diffuses into the quantitative pipeline between valve 4 14 and valve 5 15;

[0061] 3) Close valve 11 and valve 4 14, open valve 5 15, allow gas to diffuse freely into the CuO furnace 3, and close valve 3 13;

[0062] 4) Open valve six 16 and allow the remaining gas to diffuse freely into the main line. Use getter one 7 and getter two 8 to adsorb the active gas in the main line. Then, use liquid nitrogen to cool the activated carbon stainless steel cold trap 9 to adsorb the argon therein. To ensure the adsorption effect, this process needs to be maintained for 20 minutes. Then, use liquid nitrogen to cool the activated carbon cold trap and maintain it for 10 minutes to adsorb the argon therein. At the same time, use a muffle furnace to heat the CuO furnace 3. First, heat it to 850°C and hold it for 15 minutes. Then, reduce the temperature to 600°C and hold it for 15 minutes. Finally, reduce the temperature to 450°C and hold it for 15 minutes.

[0063] 5) Because the noble gas purification time is short, the noble gases are analyzed first. While the temperature of the CuO furnace 3 is maintained, valve 12 22 is closed, valve 13 23 is opened, and the He and Ne gases not adsorbed by the activated carbon stainless steel cold trap 9 are analyzed using a noble gas mass spectrometer 10;

[0064] 6) After the analysis of He and Ne gases is completed, valve 11 21 is opened to remove the analyzed gases, valve 11 21 is closed, valve 12 22 is opened to restore the activated carbon stainless steel cold trap 9 to room temperature to release the originally adsorbed Ar, and then valve 13 23 is opened to continue analysis;

[0065] 7) After the analysis is completed, valve 11 21 is opened to remove the analyzed gas. Valve 11 21, valve 7 17, valve 8 18, and valve 12 22 are closed. Valve 3 13 is opened to allow the CuO gas sample to diffuse freely into the CT quartz trap. Liquid nitrogen is used to cool the CT quartz trap. The inner wall of the CT quartz trap can adsorb the CO2 generated by the reaction with CuO. To ensure the effectiveness of the adsorption, the adsorption time needs to be maintained for 20 minutes.

[0066] 8) Open valve 13 23 to allow the remaining adsorbed gas (mainly nitrogen) to diffuse freely into the noble gas mass spectrometer 10 for N isotope analysis until the measurement is completed.

[0067] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A device for combined testing of trace sample nitrogen and noble gas isotopes, characterized by: The invention comprises a laser sample tray, a vacuum system, a CuO furnace, an air standard sample, a CT quartz cold trap, an ion pump, a getter 1, a getter 2, an activated carbon stainless steel cold trap and a rare gas mass spectrometer; wherein the laser sample tray is connected to the rare gas mass spectrometer through a main pipe, and the vacuum system, the CuO furnace, the air standard sample, the CT quartz cold trap, the ion pump, the getter and the activated carbon stainless steel cold trap are sequentially connected to the main pipe from the head end to the tail end; a valve 1 is provided on the main pipe at the outlet of the laser sample tray, a valve 2 is provided between the vacuum system and the main pipe, a valve 3 is provided between the CuO furnace and the main pipe, the air standard sample is connected to the main pipe, and the vacuum system, the CuO furnace and the main pipe are connected to the main pipe. Valve four and valve five are provided between the main line, valve six is provided between the air standard and the getter one, valve seven is provided between the getter one and the main line, valve eight is provided on the main line between the getter one and the getter two, valve nine is provided between the getter two and the main line, valve ten is provided on the main line between the CT quartz cold trap and the ion pump, valve eleven is provided between the ion pump and the main line, valve twelve is provided between the activated carbon stainless steel cold trap and the main line, and valve thirteen is provided on the main line at the entrance of the rare gas mass spectrometer.

2. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: A diamond sample window is provided above the laser sample disk, and the infrared laser can heat or even melt the sample through the sample window.

3. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: The vacuum system is a double-stage vacuum structure of dry pump plus molecular pump, which can pump the air pressure of the pipeline to 1*10 -6 Below Pa.

4. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: The CuO furnace is a quartz tube with a CF16 metal interface. 2 to 5 g of CuO powder is arranged in the quartz tube. A muffle furnace is arranged on the outer shell of the quartz tube. The muffle furnace can heat the quartz tube to 1000°C.

5. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: A quantitative pipeline is provided between the valve 4 and the valve 5.

6. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: The getter 1 and the getter 2 are both ST101 getter materials, and a heating wire is provided inside the ST101 getter material. The getter 1 and the getter 2 are externally connected to the main pipe through valve 7 and valve 9 respectively via CF16 flanges.

7. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: The CT quartz cold trap is a quartz tube with a CF16 metal interface. The outer surface of the quartz tube is covered with a thermos cup filled with liquid nitrogen for adsorbing chemically generated CO2 gas.

8. The device for combined testing of trace sample nitrogen and noble gas isotopes according to claim 1, characterized in that: The activated carbon stainless steel trap is a stainless steel tube with a CF16 metal interface. A thermos cup filled with liquid nitrogen is sheathed outside the stainless steel tube for adsorbing argon.

9. A method for combined testing of trace nitrogen samples and noble gas isotopes, using the apparatus for combined testing of trace nitrogen samples and noble gas isotopes according to any one of claims 1 to 8, characterized in that: It includes two processes: sample analysis and air analysis calibration; Sample analysis includes the following steps: 1) Open valve 1, valve 2, valve 3, valve 6, valve 7, valve 8, valve 9, valve 10, and valve 12, and keep the other valves closed. Use the vacuum system to evacuate the entire pipeline; 2) Close valve 1 and use laser to heat the sample to be analyzed; 3) Close valve 2 and valve 6, open valve 1 to allow the heated gas sample to diffuse freely into the CuO furnace, and close valve 3; 4) Open valve 6 and allow the remaining gas to diffuse freely into the main line. Getter 1 and adsorbent 2 adsorb the active gas in the main line. Then, liquid nitrogen is used to cool the activated carbon stainless steel cold trap to adsorb the argon gas. At the same time, the CuO furnace is heated using a muffle furnace. 5) First, analyze the rare gases. While the CuO furnace temperature is maintained, close valve 1 and open valve 13. Use a rare gas mass spectrometer to analyze the He and Ne gases that are not adsorbed by the activated carbon stainless steel cold trap. 6) After the analysis of He and Ne gases is completed, valve 11 is opened to extract the analyzed gases, valve 11 is closed and valve 12 is opened to return the activated carbon stainless steel cold trap to room temperature to release the originally adsorbed Ar, and then valve 13 is opened for analysis; 7) After the analysis is completed, open valve 11 to remove the analyzed gas, close valves 11, 7, 8, and 12, and open valve 3 to allow the CuO gas sample to diffuse freely into the CT quartz trap. Use liquid nitrogen to cool the CT quartz trap so that the inner wall of the CT quartz trap can adsorb the CO2 generated by the reaction with CuO. 8) Open valve 13 to allow the remaining adsorbed gas to diffuse freely into the noble gas mass spectrometer for N isotope analysis until the measurement is completed; Air analysis includes the following steps: 1) Open valves 1, 2, 3, 6, 7, 8, 9, 10, and 12, and keep the other valves closed. Use the vacuum system to evacuate the entire pipeline. 2) Open valve 4 and allow the gas to diffuse freely into the quantitative pipeline between valves 4 and 5; 3) Close valve 1 and valve 4, open valve 5, allow the gas to diffuse freely into the CuO furnace, and close valve 3; 4) Open valve 6 and allow the remaining gas to diffuse freely into the main line. Use getter 1 and getter 2 to adsorb the active gas in the main line. Then use liquid nitrogen to cool the activated carbon stainless steel cold trap to adsorb the argon gas. At the same time, use a muffle furnace to heat the CuO furnace. 5) First, analyze the rare gases. While the CuO furnace temperature is maintained, close valve 12 and open valve 13. Use a rare gas mass spectrometer to analyze the He and Ne gases that are not adsorbed by the activated carbon stainless steel cold trap. 6) After the analysis of He and Ne gases is completed, valve 11 is opened to remove the analyzed gases, valve 11 is closed, valve 12 is opened to restore the activated carbon stainless steel cold trap to room temperature to release the originally adsorbed Ar, and then valve 13 is opened to continue analysis; 7) After the analysis is completed, open valve 11 to remove the analyzed gas, close valves 11, 7, 8, and 12, and open valve 3 to allow the CuO gas sample to diffuse freely into the CT quartz trap. Use liquid nitrogen to cool the CT quartz trap so that the inner wall of the CT quartz trap can adsorb the CO2 generated by the reaction with CuO. 8) Open valve 13 to allow the remaining adsorbed gas to diffuse freely into the noble gas mass spectrometer for N isotope analysis until the measurement is completed.

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