A gas sample in-situ sampling device

Abstract

The present invention belongs to the technical field of gas sample sampling, and relates to an in-situ sampling device for gas samples. The in-situ sampling device for gas samples includes a sampling tube and a sample storage tube; the sample storage tube is detachably covered on the sampling tube to form a sample storage inner cavity; the side wall of the sampling tube is provided with an opening portion, and a gas exchange membrane layer is provided on the sample storage inner cavity side of the opening portion; a metal perforated mesh is provided on the outside of the opening portion, and a liquid-gas exchange cavity is formed between the gas exchange membrane layer and the metal perforated mesh; a plug body is provided on the end of the sample storage tube away from the sampling tube, and also includes a gas suction tube, which is passed through the plug body, and a valve body is provided on the side of the gas suction tube away from the sample storage tube. The present invention can perform in-situ sampling of CH4 gas at different depths of paddy field soil without disturbing the soil profile, and the process is simple and the measurement is accurate. At the same time, the artificial disturbance of the soil system is minimized to the greatest extent, and the reliability and stability of the sampling results under different paddy field soil moisture conditions are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sample sampling and relates to an in-situ sampling device for gas samples. Background Art

[0002] Stable carbon isotopes ( 13 C) tracing technology is an important technical means to study the fixation, distribution, and transformation of rice C and its biogeochemical cycle in soil. 13 C isotope tracing technology can be used to safely and reliably implement and measure the test. 13 There are three main methods for C labeling in the world: single pulse labeling, repeated pulse labeling, and continuous labeling. Pulse labeling is a single sufficient labeling method. 13 C tracer technology is currently commonly used in agricultural research 13 C markers mainly include 13 CO2, 13 C-cellulose, 13 C-hemicellulose and 13 C-glucose, etc. Compared with other labeling techniques, pulse labeling has many advantages. Its application scenarios involve the research on plant C fixation, distribution and transport under natural and artificial ecosystem conditions. It can also provide information on material distribution and transformation at different growth stages of plants, dynamically monitor the transformation of plant-related metabolites in the soil, and accurately reflect the transformation and migration process of C in the atmosphere-plant-soil system.

[0003] In recent years, 13 The application of C labeling technology in the C metabolism and transformation process in paddy soil has attracted widespread attention from relevant academic circles. 13 Taking CO2 tracer as an example, a large number of studies have shown that 13 After the C marker enters the rice field ecosystem through photosynthesis of rice plants, a portion of it is fixed by the rice plants and becomes the biomass of the rice plants. 13 C markers re-enter the atmosphere or soil system through plant respiration or in the form of root secretions. CH4 is an important product of the paddy soil C cycle and is also the second largest greenhouse gas after CO2. The academic community has paid more and more attention to the source, distribution and transformation of CH4 metabolic substrates in paddy soils. 13 C labeling technology can accurately reflect the conversion process of C substrate to CH4 in the plant-soil-atmosphere system. However, due to the complexity of the soil system and the lack of research methods, how to explain the distribution and transfer rules of relevant markers in paddy soil under the premise of minimizing human disturbance caused by the observation process, the key lies in whether it can accurately quantify the distribution and transfer of relevant markers at different points in the soil under the condition of minimizing human disturbance.13 Distribution and abundance of CH4. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an in-situ sampling device for gas samples to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention provides, on the one hand, an in-situ sampling device for gas samples, comprising a sampling tube and a sample storage tube; the sample storage tube is detachably covered on the sampling tube to form a sample storage inner cavity; the side wall of the sampling tube is provided with an opening portion, and the sample storage inner cavity side of the opening portion is provided with a gas exchange membrane layer that matches the opening portion; the outer side of the opening portion is provided with a metal perforated mesh that matches the opening portion, and a liquid-gas exchange cavity is formed between the gas exchange membrane layer and the metal perforated mesh; a plug body is provided on the end of the sample storage tube away from the sampling tube, and also includes a gas suction tube, the gas suction tube is passed through the plug body and is at least partially provided in the sample storage inner cavity, and a valve body is provided on the side of the gas suction tube away from the sample storage tube.

[0006] In some embodiments of the present invention, the sampling tube and the sample storage tube are threadedly connected.

[0007] In some embodiments of the present invention, a first sealing member is provided between the sampling tube and the sample storage tube.

[0008] In some embodiments of the present invention, the membrane edge of the gas exchange membrane layer is connected to the inner wall of the sample storage cavity through a second seal.

[0009] In some embodiments of the present invention, elastic pressure rings are provided on both sides of the second sealing member.

[0010] In some embodiments of the present invention, the two ends of the liquid-gas exchange chamber that are in contact with the side wall of the sampling tube are respectively provided with support brackets.

[0011] In some embodiments of the present invention, the mesh size of the metal perforated mesh is 90-110 mesh.

[0012] In some embodiments of the present invention, the first sealing member is selected from a sealing ring.

[0013] In some embodiments of the present invention, the second sealing member is selected from a waterproof sealant patch.

[0014] Another aspect of the present invention provides a method for measuring methane (CH4) gas in paddy field soil 13 The method for measuring C abundance comprises the following steps:

[0015] 1) Using the gas sample in-situ sampling device of the present invention, opening the valve body, completely replacing the original gas in the sample storage cavity with an inert gas through the gas exchange membrane layer, and closing the valve body;

[0016] 2) determining the soil gas sampling depth, and inserting the in-situ sampling device of the gas sample processed in step 1) into the soil to a predetermined depth;

[0017] 3) opening the valve body, extracting part of the inert gas from the sample storage cavity, and forming a negative pressure state in the sample storage cavity with respect to the valve body;

[0018] 4) placing the gas sample in-situ sampling device in the soil for 0.9 to 1.1 hours, so that the CH4 dissolved in the soil micropores and soil interstitial water is fully exchanged and mixed with the inert gas in the sample storage cavity to obtain a mixed gas sample;

[0019] 5) extracting the mixed gas sample obtained in step 4) from the sample storage cavity through the valve body into a vacuum glass gas sample bottle;

[0020] 6) Using an isotope mass spectrometer to analyze the gas in the vacuum glass gas sample bottle described in step 5) 13 The CH4 abundance was measured.

[0021] The paddy field soil CH4 gas sampling device provided by the present invention can perform in-situ sampling of CH4 gas at different depths in the paddy field soil without disturbing the soil profile. The process is simple and the measurement is accurate. At the same time, it minimizes the artificial disturbance of the soil system and ensures the reliability and stability of the sampling results under different paddy field soil moisture conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is a schematic structural diagram of the in-situ sampling device for gas samples of the present invention.

[0023] Figure 2 Shown is a perspective view of the sampling tube structure in the in-situ sampling device for gas samples of the present invention.

[0024] Figure 3 Shown is a schematic diagram of the sampling principle of the sampling tube in the gas sample in-situ sampling device of the present invention.

[0025] Figure 4 The diagram shows the use status of the gas sample in-situ sampling device of the present invention in soil.

[0026] Component numbers in the figure

[0027] 1 Sample storage tube

[0028] 2 Sampling tube

[0029] 3 Sample storage cavity

[0030] 4 Opening

[0031] 5 Gas exchange membrane layer

[0032] 6 Metal Perforated Mesh

[0033] 7 Liquid-gas exchange chamber

[0034] 8 Plug body

[0035] 9 Gas suction pipe

[0036] 10 Valve body

[0037] 11 First seal

[0038] 12 Second seal

[0039] 13 Elastic pressure ring

[0040] 14 Support bracket

[0041] 15 Soil DETAILED DESCRIPTION

[0042] In the description of the present invention, it should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of the present specification are only used to match the contents disclosed in the specification for people familiar with the technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the directions or positional relationships indicated by the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0045] like Figures 1 to 3 The embodiment of the present invention relates to an in-situ sampling device for gas samples, which comprises a sampling tube 2 and a sample storage tube 1; the sample storage tube 1 is detachably covered on the sampling tube 2 to form a sample storage cavity 3; the side wall of the sampling tube 2 is provided with an opening portion 4, and the side of the sample storage cavity 3 of the opening portion 4 is provided with a gas exchange membrane layer 5 that matches the opening portion 4. Since the wall of the sampling tube 2 has a certain thickness, the formed opening portion 4 also has a certain thickness. Here, the gas exchange membrane layer 5 matches the side of the sample storage cavity 3 of the opening portion 4, which specifically means that the gas exchange membrane layer 5 can completely cover the side of the opening portion 4 located on the side of the sample storage cavity 3. The outer side of the opening portion 4 is provided with a metal perforated mesh 6 that matches the opening portion 4. Here, the metal perforated mesh 6 matches the outer side of the opening portion 4, which specifically means that the metal perforated mesh 6 can completely cover the side of the outer side of the opening portion 4. As mentioned above, the opening 4 has a certain thickness, so a liquid-gas exchange cavity 7 can be formed between the gas exchange membrane layer 5 and the metal perforated mesh 6. The end of the sample storage tube 1 away from the sampling tube 2 is provided with a plug body 8, and also includes a gas suction tube 9, which is penetrated by the plug body 8 and at least partially arranged in the sample storage cavity 3, and a valve body 10 is arranged on the side of the gas suction tube 9 away from the sample storage tube 1. The gas sample in-situ sampling device of the present invention can be applied to CH4 gas sampling of paddy soil, and can perform in-situ sampling of CH4 gas at different depths of paddy soil 15 without disturbing the cross section of the soil 15. The process is simple and the measurement is accurate. At the same time, the artificial disturbance of the soil system is minimized to the greatest extent, and the reliability and stability of the sampling results under different paddy soil moisture conditions are ensured. At the same time, the gas exchange membrane layer 5 and other consumables are provided on the opening 4 in the sampling tube. When the consumables such as the gas exchange membrane reach the end of their service life, due to the detachable setting of the sampling tube 2 and the sample storage tube 1, only part of the sampling tube 2 can be discarded, and the sample storage tube 1 can be reused.

[0046] In the gas sample in-situ sampling device provided by the present invention, Figure 1The bottom of the sampling tube 2 is a pointed part, which is convenient for inserting into the soil 15. The material of the sampling tube 2 can be, for example, a metal material, and more preferably, a stainless steel material (304 stainless steel, etc.). Normally, the wall of the sampling tube 2 has a certain thickness, for example, it can be 1.9 to 2.1 mm. The length of the sampling tube 2 is 4.9 to 5.1 cm, the inner diameter of the non-pointed part of the sampling tube 2 is 1.4 to 1.6 cm, and the outer diameter is 1.7 to 2.0 cm. The sampling tube 2 is used for puncturing the soil 15 and bearing the pressure of the structure.

[0047] In the gas sample in-situ sampling device provided by the present invention, Figure 1 The material of the sample storage tube 1 can be, for example, metal, and more preferably, stainless steel (304 stainless steel, etc.). The length of the sample storage tube 1 can usually be determined according to the amount of gas sampling, and the length of the sample storage tube 1 can be, for example, 10 to 25 cm. For example, the length of the sample storage tube for a gas sampling amount of 10 ml under normal pressure conditions should be 20 cm. The inner diameter and outer diameter of the sample storage tube 1 are respectively matched with the sampling tube 2, with an inner diameter of 1.4 to 1.6 cm and an outer diameter of 1.7 to 2.0 cm.

[0048] In the gas sample in-situ sampling device provided by the present invention, Figure 1 , the sampling tube 2 and the sample storage tube 1 are threadedly connected. Specifically, the sampling tube 2 is provided with an external thread, and the sample storage tube 1 is provided with an internal thread matching the external thread. It is used to connect the sampling tube 2 and the sample storage tube 1. More specifically, the sample storage tube 1 uses 304 stainless steel inner wall tapping, and the sampling tube 2 uses 304 stainless steel outer wall tapping, so that the sampling tube 2 can be screwed into the sample storage tube 1.

[0049] In the gas sample in-situ sampling device provided by the present invention, Figure 1 and 2 , a first sealing member 11 is provided between the sampling tube 2 and the sample storage tube 1. In one embodiment, the first sealing member 11 is selected from a sealing ring. The sealing ring can be, for example, an impermeable silicone sealing ring. When used specifically, the impermeable silicone sealing ring can be nested in the threaded connection between the sampling tube 2 and the sample storage tube 1. The thickness of the sealing ring is 1.4 to 1.6 mm, and the inner diameter is 1.5 to 1.7 cm. The first sealing member 11 is used to prevent gas or liquid exchange at the interface between the sampling tube 2 and the sample storage tube 1.

[0050] In the gas sample in-situ sampling device provided by the present invention, Figure 1 and 2 The side wall of the sampling tube 2 is provided with an opening portion 4, and the size of the opening portion 4 can be, for example, 0.7-0.9 cm×1.9-2.1 cm.

[0051] In the gas sample in-situ sampling device provided by the present invention, Figure 1 and2 , a gas exchange membrane layer 5 matching with the opening portion 4 is provided on the side of the sample storage cavity 3 of the opening portion 4. The membrane edge of the gas exchange membrane layer 5 is connected to the sample storage cavity 3 through the second seal 12. The material of the gas exchange membrane layer 5 can be, for example, an ePTFE gas exchange membrane. The second seal 12 can be a hydrophobic non-woven fabric base, and more for example, can be a waterproof sealant patch. The inner side of the ePTFE gas exchange membrane is implanted in a hydrophobic non-woven fabric base. It can be understood that the outer edge of the ePTFE gas exchange membrane uses an elliptical cloth-based waterproof sealant patch with a middle opening to tightly bond to the inner wall of the sample storage cavity 3.

[0052] In the gas sample in-situ sampling device provided by the present invention, Figure 1 and 2 , elastic pressure rings 13 are provided on both sides of the second sealing member 12. The elastic pressure ring 13 may be, for example, a spring pressure ring. The spring pressure ring is made of a C-shaped weather-resistant spring steel material. It can fit tightly with the second sealing member 12, and is respectively arranged on the upper and lower sides of the second sealing member 12 (for example, a waterproof sealant patch) to compact and support the second sealing member 12 (for example, a waterproof sealant patch).

[0053] In the gas sample in-situ sampling device provided by the present invention, the outer side of the opening portion 4 is provided with a metal perforated mesh 6 that matches the opening portion 4. The metal perforated mesh 6 can be a stainless steel perforated mesh. The stainless steel perforated mesh can be welded to the outer side of the opening portion 4 on the sampling tube 2. The mesh size of the metal perforated mesh 6 is 90 to 110 mesh. It is used to prevent large particles of sediment in the soil 15 from damaging the gas exchange membrane layer 5. Figure 3 When in use, CH4 dissolved in the micropores of the soil 15 and the interstitial water of the soil 15 can first enter the liquid-gas exchange cavity 7 through the mesh of the metal perforated mesh 6, and then enter the sample storage cavity 3 through the gas exchange membrane layer 5 to exchange or mix with nitrogen. Large particles of sediment and water in the soil will not pass through the gas exchange membrane layer 5, but return to the soil through the mesh of the metal perforated mesh 6.

[0054] In the gas sample in-situ sampling device provided by the present invention, the two ends of the liquid-gas exchange cavity 7 in contact with the side wall of the sampling tube 2 are respectively provided with support brackets 14. The support bracket 14 can be a PE composite silicone liner bracket, which is made by adding plastic silicone demoulding to the PE bracket, and is used to support the gap between the metal perforated mesh 6 and the gas exchange membrane layer 5 as the liquid-gas exchange cavity 7 (liquid-gas two-phase exchange cavity), and is also used to prevent the liquid exchange membrane layer from over-deformation when it is under pressure.

[0055] In the gas sample in-situ sampling device provided by the present invention, the plug body 8 can be, for example, a gas-tight plug of the sample storage cavity 3 .

[0056] In the gas sample in-situ sampling device provided by the present invention, the gas suction tube 9 may be, for example, a silicone capillary tube.

[0057] In the gas sample in-situ sampling device provided by the present invention, the valve body 10 may be, for example, a gas three-way valve.

[0058] The working process of the gas sample in-situ sampling device provided by the present invention is as follows:

[0059] When using, Figure 4 , after assembling the in-situ sampling device for gas samples, before inserting the in-situ sampling device for gas samples into the paddy field soil 15 to be measured, push an inert gas, such as high-purity nitrogen (N2), into the sample storage cavity 3 through a syringe connected to a valve body 10 (such as a gas three-way valve), so that the original gas inside the sample storage cavity 3 is replaced through the gas exchange membrane layer 5 from the side wall of the sampling tube 2. After determining that all the original gas in the sample storage cavity 3 has been replaced by high-purity nitrogen (N2), close the valve body 10 in time. After further determining the gas sampling depth of the soil 15, insert the in-situ sampling device for gas samples filled with high-purity nitrogen (N2) into the paddy field soil 15 to a predetermined depth in time. Open the valve body 10 (such as a gas three-way valve) again, and according to the selected casing specifications, extract about 1 / 5 of the high-purity N2 in the sample storage cavity 3, so that a negative pressure state is formed in the probe cavity, and then close the valve body 10 again. After completing the above operations, as Figure 3 The gas sample in-situ sampling device was placed in the paddy soil 15 for 1 hour to allow the dissolved CH4 in the micropores of the soil 15 and the interstitial water of the soil 15 to fully exchange and mix with the high-purity N2 in the sample storage cavity 3 to obtain a mixed gas sample. After the gas sample in-situ sampling device was left to stand, the mixed gas sample in the sample storage cavity 3 was extracted again by a syringe and transferred to a vacuum glass cylinder for storage for subsequent 13 CH4 abundance determination. 13 The abundance of CH4 has nothing to do with the CH4 concentration in the gas sample, but only depends on the 12 C and 13 Therefore, for samples with less gas extraction in the sample storage cavity 3, it is necessary to inject high-purity N2 into the glass gas sample bottle to make up the volume of the bottle to 20mL. The above mixed gas sample was analyzed by an isotope mass spectrometer model Thermo Scientific Delta V Plus. 13 The CH4 abundance is measured and the final measurement result is obtained.

[0060] The second aspect of the present invention provides a method for measuring methane (CH4) gas in paddy field soil. 13 The method for measuring the abundance of C, using the gas sample in-situ sampling device of the present invention, comprises the following steps:

[0061] 1) Open the valve body 10, replace all the original gas in the sample storage cavity 3 with inert gas through the gas exchange membrane layer 5, and close the valve body 10. The inert gas may be, for example, high-purity nitrogen.

[0062] 2) Determine the soil gas sampling depth, and insert the in-situ sampling device of the gas sample processed in step 1) into the predetermined depth of the soil.

[0063] 3) Open the valve body 10, extract part of the inert gas from the sample storage cavity 3, and form a negative pressure state in the sample storage cavity 3, with respect to the valve body 10. Part of the inert gas can be, for example, 1 / 5 of nitrogen.

[0064] 4) The gas sample in-situ sampling device is placed in the soil for 0.9 to 1.1 hours to allow the dissolved CH4 in the soil micropores and soil interstitial water to fully exchange and mix with the inert gas in the sample storage cavity 3 to obtain a mixed gas sample.

[0065] 5) extracting the mixed gas sample obtained in step 4) from the sample storage cavity 3 through the valve body 10 into a vacuum glass gas sample bottle;

[0066] 6) Using an isotope mass spectrometer to analyze the gas in the vacuum glass gas sample bottle described in step 5) 13 The CH4 abundance was measured.

[0067] In summary, the paddy field soil CH4 gas sampling device provided by the present invention can perform in-situ sampling of CH4 gas at different depths in the paddy field soil without disturbing the soil profile. The process is simple and the measurement is accurate. At the same time, it minimizes the artificial disturbance of the soil system and ensures the reliability and stability of the sampling results under different paddy field soil moisture conditions.

[0068] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A gas sample in-situ sampling device, characterized in that: The gas sample in-situ sampling device comprises a sampling tube (2) and a sample storage tube (1); the sample storage tube (1) is detachably covered on the sampling tube (2) to form a sample storage cavity (3); the side wall of the sampling tube (2) is provided with an opening portion (4); the sample storage cavity side of the opening portion (4) is provided with a gas exchange membrane layer (5) matching with the opening portion (4); the membrane edge of the gas exchange membrane layer (5) is connected to the inner wall of the sample storage cavity (3) through a second sealing member (12); the outer side of the opening portion (4) is provided with a metal punching member matching with the opening portion (4); A perforated mesh (6), a liquid-gas exchange cavity (7) is formed between the gas exchange membrane layer (5) and the metal perforated mesh (6), and the two ends of the liquid-gas exchange cavity (7) in contact with the side wall of the sampling tube (2) are respectively arranged on a support bracket (14); a plug body (8) is arranged on the end of the sample storage tube (1) away from the sampling tube (2), and also includes a gas suction tube (9), the gas suction tube (9) is passed through the plug body (8) and is at least partially arranged in the sample storage cavity (3), and a valve body (10) is arranged on the side of the gas suction tube (9) away from the sample storage tube (1).

2. The gas sample in-situ sampling device according to claim 1, characterized in that: The sampling tube (2) and the sample storage tube (1) are threadedly connected.

3. The gas sample in-situ sampling device according to claim 1, characterized in that: A first sealing member (11) is provided between the sampling tube (2) and the sample storage tube (1).

4. The gas sample in-situ sampling device according to claim 3, characterized in that: The first sealing member (11) is selected from a sealing ring.

5. The gas sample in-situ sampling device according to claim 1, characterized in that: Elastic pressure rings (13) are provided on both sides of the second sealing member (12).

6. The gas sample in-situ sampling device according to claim 1, characterized in that: The second sealing member (12) is selected from a waterproof sealant patch.

7. The gas sample in-situ sampling device according to claim 1, characterized in that: The mesh size of the metal perforated mesh (6) is 90-110 meshes.

8. A method for measuring methane gas in paddy soil 13 The method for measuring C abundance comprises the following steps: 1) Using the gas sample in-situ sampling device according to any one of claims 1 to 7, opening the valve body (10), completely replacing the original gas in the sample storage cavity (3) with an inert gas through the gas exchange membrane layer (5), and closing the valve body (10); 2) determining the soil gas sampling depth, and inserting the in-situ sampling device of the gas sample processed in step 1) into the soil to a predetermined depth; 3) opening the valve body (10) and extracting a portion of the inert gas from the sample storage cavity (3), thereby forming a negative pressure state in the sample storage cavity (3) with respect to the valve body (10); 4) placing the gas sample in-situ sampling device in the soil for 0.9 to 1.1 hours, so that the CH4 dissolved in the soil micropores and soil interstitial water is fully exchanged and mixed with the inert gas in the sample storage cavity (3) to obtain a mixed gas sample; 5) extracting the mixed gas sample obtained in step 4) from the sample storage cavity (3) through the valve body (10) into a vacuum glass gas sample bottle; 6) Using an isotope mass spectrometer to analyze the gas in the vacuum glass gas sample bottle described in step 5) 13 The CH4 abundance was measured.

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