Greenhouse gas measurement method and measurement device

Abstract

One aspect according to the present invention is a method for measuring, by using gas chromatography (GC), three types of greenhouse gases, CO2, CH4, and N2O, in the atmosphere, the method comprising: a separation step for introducing the atmosphere which may contain three types of greenhouse gas components into a GC column 15 and separating, in the time direction, each component of the atmosphere including said components; a first detection step for using a barrier discharge ionization detector (BID) 16 to respectively detect CO2 and N2O in the gas after the components have been separated in the separation step; a second detection step for using a flame ionization detector (FID) 17 to detect CH4 in the gas after the components have been separated in the separation step; and a quantity processing step for preparing a chromatogram for each on the basis of the detection signals obtained in the first and second detection steps and respectively quantify CO2, CH4, and N2O from the peaks observed in the chromatograms. Using the method according to this aspect, CO2, CH4, and N2O in the atmosphere can be measured simultaneously in a simpler manner with high sensitivity.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for measuring greenhouse gases in the atmosphere using a gas chromatograph (hereinafter sometimes abbreviated as "GC"). [Background technology]

[0002] The rapid progress of global warming in recent years has led to rising sea levels and more frequent extreme weather events, raising concerns that it will have a major impact on natural ecosystems, living environments, agriculture, forestry, and fisheries. The main cause of global warming is the increase in so-called greenhouse gases in the atmosphere, which are emitted by human industrial activities. In terms of the proportion of greenhouse gases emitted, carbon dioxide (CO2) accounts for the largest share, followed by methane (CH4) and nitrous oxide (N2O). For these reasons, it is extremely important to continuously monitor the atmospheric concentrations of these major greenhouse gases as part of efforts to prevent global warming.

[0003] A method using GC is known as a method for measuring the concentrations of CO2, CH4, and N2O in the atmosphere. GC uses various types of detectors depending on the type and characteristics of the components to be measured. When measuring CO2, CH4, and N2O in the atmosphere using GC, the detectors typically used are a thermal conductivity detector (TCD) for CO2, a flame ionization detector (FID) for CH4, and an electron capture detector (ECD) for N2O. For example, Patent Document 1 describes a system that uses these three types of detectors to simultaneously measure the concentrations of CO2, CH4, and N2O in the atmosphere with a single sample injection. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-275844 [Patent Document 2] Patent No. 5136300 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional measurement system described in Patent Document 1, in order to sufficiently separate the three components, multiple thermostatic chambers with different temperatures and multiple columns housed in those chambers are used, and the multiple columns and detectors are switched by switching the flow path using a flow path switching valve as time passes from the time of sample injection. This results in a rather complex and large-scale device configuration, which is expensive and lacks versatility. Furthermore, because ECD uses radioisotopes, there are also problems with cumbersome maintenance and management.

[0006] The present invention has been made to solve these problems, and its main object is to provide a method and apparatus that can measure the major greenhouse gases, CO2, CH4, and N2O in the atmosphere simultaneously (by a single sample injection) more simply and with high sensitivity. [Means for solving the problem]

[0007] One aspect of the greenhouse gas measurement method according to the present invention, which has been made to solve the above problems, is a method for measuring three greenhouse gases contained in the atmosphere, namely, carbon dioxide, methane, and nitrous oxide, using a gas chromatograph, comprising the steps of: a separation step of introducing the atmosphere that may contain the three greenhouse gas components into a gas chromatograph column and separating various components in the atmosphere that contain the components in a time direction; a first detection step of detecting carbon dioxide and nitrous oxide in the gas after the component separation in the separation step using a dielectric barrier discharge ionization detector; a second detection step of detecting methane in the gas after the component separation in the separation step using a hydrogen flame ionization detector; a quantitative processing step of preparing chromatograms based on the detection signals obtained in the first detection step and the second detection step, and quantifying carbon dioxide, nitrous oxide, and methane from peaks observed in the chromatograms; It has.

[0008] Furthermore, one aspect of the greenhouse gas measuring device according to the present invention is a device for measuring three greenhouse gases contained in the atmosphere, namely, carbon dioxide, methane, and nitrous oxide, comprising: a gas chromatograph column for separating various components in the atmosphere, which may contain the three greenhouse gas components, in a time direction; a dielectric barrier discharge ionization detector for detecting carbon dioxide and nitrous oxide in the gas after component separation in the column; a hydrogen flame ionization detector for detecting methane in the gas after detection by the dielectric barrier discharge ionization detector; a quantitative processing unit that creates chromatograms based on the detection signals obtained by the dielectric barrier discharge ionization detector and the hydrogen flame ionization detector, and that quantitatively determines the amounts of carbon dioxide, nitrous oxide, and methane from peaks observed in the chromatograms; Equipped with. [Effects of the Invention]

[0009] According to the above-described aspects of the greenhouse gas measurement method and measurement device of the present invention, it is possible to measure carbon dioxide, methane, and nitrous oxide, which are major greenhouse gases in the atmosphere, with high sensitivity using a device with a simple and inexpensive configuration that does not involve complex flow path switching, etc. This makes it possible to measure greenhouse gases easily and at low cost. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an embodiment of a measurement device for carrying out a greenhouse gas measurement method according to the present invention. [Figure 2] FIG. 2 is a schematic diagram of a BID used in the greenhouse gas measuring device of the present embodiment. [Figure 3] FIG. 10 is a configuration diagram of the main part of another embodiment of a measurement device for carrying out a greenhouse gas measurement method according to the present invention. [Figure 4] FIG. 10 is a configuration diagram of the main part of another embodiment of a measurement device for carrying out a greenhouse gas measurement method according to the present invention. [Figure 5] This figure shows an example of a chromatogram of air obtained by GC using a BID as a detector. [Figure 6] FIG. 2 shows an example of a chromatogram of the atmosphere obtained using the measurement device shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Measurement principle] In recent years, dielectric barrier discharge ionization detectors (hereinafter sometimes abbreviated as "BIDs"), as described in Patent Document 2 and elsewhere, have been put into practical use as GC detectors. BIDs are detectors that use light energy emitted from low-frequency dielectric barrier discharge plasma to ionize molecules of target components in a gas, and then capture the ions on an electrode to extract the ion current that flows. In principle, BIDs can detect all components except helium (He) and neon (Ne), making them particularly useful for analyzing inorganic gases. However, this also means that when a wide variety of components are present, such as in the atmosphere, multiple components may be detected overlapping unless the target component and other impurity components are sufficiently separated before being introduced into the BID.

[0012] Figure 5 shows an example of a chromatogram obtained by measuring atmospheric air using a GC with a BID detector. The concentrations of CO2, CH4, and N2O in the atmosphere are approximately 410 ppm, 1.8 ppm, and 0.32 ppm, respectively. A Micropacked ST column manufactured by Shinwa Chemical Industry Co., Ltd. was used. As shown in Figure 5, the major components of the atmosphere, O2 and N2, are sufficiently separated from CO2, CH4, and N2O. Low concentrations of CH4 and N2O, as well as relatively high concentrations of CO2, are all detected with sufficient intensity. However, krypton (Kr) present in the atmosphere is also detected, and the Kr peak partially overlaps with the CH4 peak. This makes it difficult to accurately quantify CH4 from this chromatogram.

[0013] To solve this problem, the inventors came up with a method of using a BID to detect CO2 and NO and an FID to detect CH4. While an FID has high detection sensitivity for organic compounds (with some exceptions), it is not sensitive to Kr. Therefore, as shown in Figure 5, it is possible to selectively detect only CH4 even when CH4 and Kr are not sufficiently separated, thereby achieving high quantitative accuracy. Furthermore, both the BID and FID can use helium as a carrier gas, which is advantageous in that it does not require the addition of another gas midway through the flow path, as in the system described in Patent Document 1.

[0014] In a GC system using both a BID and an FID, when CO2 and N2O are detected by the BID and CH4 is detected by the FID in a single sample injection, one of the following three procedures can be adopted. (Method A) A BID and an FID are connected in series to the outlet of one column, and after CO2 and N2O are detected by the BID, CH4 present in the gas is detected by the FID. (Method B) The gas coming out of the outlet of one column is split into two, one into a BID and the other into an FID, and CO2 and N2O are detected by the BID, and CH4 by the FID. (Method C) The inlets of two columns are connected to the sample introduction section, a BID is connected to the outlet of one of the two columns, and an FID is connected to the outlet of the other column, and CO2 and N2O are detected by the BID, and CH4 is detected by the FID.

[0015] Because BIDs detect gas components by ionizing them, some of the CH4 contained in the gas introduced into the BID is ionized and removed from the gas. However, most of the CH4 remains in the gas discharged from the BID. Unlike FIDs, which introduce sample gas into a hydrogen flame, BIDs discharge the introduced sample gas almost intact, except for some of the components removed and diluted by ionization. This makes them essentially nondestructive detectors. Furthermore, while Method B splits the gas containing the target component into two at the column outlet and Method C splits it into two at the column inlet, Method A splits almost all of the components sent to a single column into both the BID and FID. Therefore, Method A can detect CO2, CH4, and NO with high sensitivity and achieve high quantitative accuracy. While Methods B and C are inferior in sensitivity, they are able to achieve sufficiently high quantitative accuracy because they are not affected by insufficient separation of CH4 and Kr.

[0016] [Configuration of a measuring device according to one embodiment] As one embodiment of a measurement device for carrying out the greenhouse gas measurement method according to the present invention, a measurement device corresponding to the above-mentioned method A will be described with reference to the accompanying drawings.

[0017] Fig. 1 is a schematic diagram of the measurement device of this embodiment, and Fig. 2 is a schematic diagram of the BID in Fig. 1. Note that the descriptions of the components in Fig. 1 and Fig. 2 (as well as Fig. 3 and Fig. 4 described below) are schematic, and needless to say, do not necessarily correspond to the actual arrangement or size.

[0018] As shown in Fig. 1, this measuring device includes a GC measuring unit 1, a data processing unit 2, and a control unit 3. The GC measuring unit 1 includes a sample introduction unit 10, a gas-tight syringe 11, a flow controller 12, a column oven 13, a heater 14, a column 15, a BID 16, an FID 17, and a connecting tube 18. The column 15 can be a capillary column packed with a high-purity carbon support, specifically, a Micropacked ST column manufactured by Shinwa Chemical Industry Co., Ltd. The connecting tube 18 can be, for example, a metal column that is not packed with a packing material.

[0019] The data processing unit 2 includes, as functional blocks, a data collection unit 20, a chromatogram creation unit 21, and a quantitative calculation unit 22. A display unit 23 is connected to the data processing unit 2. The control unit 3 includes a control information storage unit 30. This control information storage unit 30 stores a measurement method including various parameter values ​​that define separation conditions as control information for controlling the GC measurement unit 1. This measurement method includes information such as the carrier gas flow rate (flow velocity), the temperature profile of the column oven, and the flow rates of various gases used in BID 16 and FID 17.

[0020] The data processing unit 2 and the control unit 3 can be configured to use a personal computer (PC) as a hardware resource, and to realize each function by executing dedicated control and processing software installed on the PC.

[0021] Next, the configuration of the BID 16 will be described with reference to FIG. The BID 16 is roughly divided into a discharge unit 101, a charge collection unit 102, and an ion current detection unit 103.

[0022] The discharge unit 101 includes a dielectric cylindrical tube 105, the interior of which is a first gas flow path 104, three annular plasma generation electrodes 106, 107, and 108 (hereinafter, the individual electrodes will be referred to as the upstream ground electrode 106, the high-voltage electrode 107, and the downstream ground electrode 108) arranged on the outer wall surface of the dielectric cylindrical tube 105 at a predetermined distance from each other in the axial direction, and an excitation high-voltage AC power supply 109. The dielectric cylindrical tube 105 is made of, for example, quartz. For convenience of explanation, the up-down direction is defined below, with the upstream side in the gas flow direction (the direction indicated by the downward arrow in Figure 2) inside the dielectric cylindrical tube 105 being the upside and the downstream side being the downside. The excitation high-voltage AC power supply 109 is connected to the high-voltage electrode 107, and both the upstream ground electrode 106 and the downstream ground electrode 108 are grounded. The excitation high voltage AC power supply 109 generates a high voltage AC voltage, for example, with a frequency of about 5 kHz to 30 kHz and a voltage of about 5 kV to 10 kV.

[0023] A gas supply pipe 110 is connected to the upper end of the dielectric cylindrical tube 105, and a plasma generation gas that also serves as a dilution gas is supplied into the first gas flow path 104 through this gas supply pipe 110. Since the wall surface of the dielectric cylindrical tube 105 exists between the plasma generation electrodes 106 to 108 and the first gas flow path 104, this wall surface itself functions as a dielectric coating layer that covers the surfaces of the plasma generation electrodes 106 to 108, enabling a dielectric barrier discharge, which will be described later.

[0024] The charge collecting unit 102 includes, in order from top to bottom, a connecting member 111 connected to the bottom end of the dielectric cylindrical tube 105, a first insulating member 112, a bias electrode 113, a second insulating member 114, an additional electrode 115, a third insulating member 116, a collecting electrode 117, a fourth insulating member 118, and a conduit terminal member 119. The first insulating member 112, the second insulating member 114, the third insulating member 116, and the fourth insulating member 118 are each made of a high-resistance material such as ultra-high purity alumina or sapphire. All of these members have a cylindrical shape, and a second gas flow path 120 that is continuous with the first gas flow path 104 is formed inside them.

[0025] A bypass exhaust pipe 121 that discharges a portion of the plasma generation gas to the outside is connected to the peripheral surface of the connecting member 111. A sample exhaust pipe 122 is connected to the lower end of the conduit terminal member 119. A through-hole is formed in the lower surface of the conduit terminal member 119, and a thin-diameter sample introduction pipe 124 is inserted into the through-hole via a seal portion 123. The lower end of the sample introduction pipe 124 is connected to the outlet end of the column 15 via a joint or the like (not shown), and gas containing sample components flowing out from the outlet of the column 15 (hereinafter referred to as "sample gas") is supplied into the second gas flow path 120 through this sample introduction pipe 124. It is also possible to insert the outlet end of the column 15 directly into the through-hole without providing the sample introduction pipe 124.

[0026] The bias electrode 113 is connected to a bias electrode DC power supply 131 included in the ion current detection unit 103, and the collecting electrode 117 is connected to a current amplifier 132 also included in the ion current detection unit 103. The additional electrode 115 is grounded, and this additional electrode 115 absorbs leakage current that flows from the bias electrode 113 to the collecting electrode 117 through the insulator surface (i.e., the inner circumferential surface of the second insulating member 114 and the inner circumferential surface of the third insulating member 116).

[0027] The ion current detection unit 103 is further provided with a collecting electrode DC power supply 133 for applying a DC voltage to the collecting electrode 117. The non-inverting input terminal of the current amplifier 132 is connected to the collecting electrode 117, and the inverting input terminal of the current amplifier 132 is connected to GND via the collecting electrode DC power supply 133. The voltages from the bias electrode DC power supply 131 and the collecting electrode DC power supply 133 are controlled by the control unit 3.

[0028] [Measurement Operation in the Measurement Apparatus of an Embodiment] The operation of the above measuring device when simultaneously measuring CO2, CH4, and N2O in the atmosphere will be described. The control unit 3 controls each part of the GC measurement unit 1 based on control information stored in the control information storage unit 30. Specifically, the temperature inside the column oven 13 is adjusted according to a predetermined profile by driving a heater 14 and a fan (not shown) attached to the column oven 13. The flow controller 12 adjusts the carrier gas, helium, to a predetermined flow rate and supplies it to the sample introduction unit 10. The gas-tight syringe 11 injects a predetermined amount of the target gas (air) into the sample introduction unit 10 at a predetermined timing. This target gas is pushed by the carrier gas and introduced into the column 15.

[0029] 1, a split flow path is connected to the sample introduction section 10, and a portion of the measurement target gas injected into the sample introduction section 10 is introduced into the column 15, and the remainder is discharged via the split flow path. Here, the measurement target gas is sent to the column 15 using the sample introduction section 10 and the gas-tight syringe 11, but a predetermined amount of the measurement target gas may be sent to the column 15 by another method such as a gas sampler.

[0030] As the gas to be measured passes through column 15, the various components in the gas are separated in time and flow out from the outlet of column 15. Therefore, the sample components in the sample gas that flows out of column 15 change over time from the time of sample injection. This sample gas flows out from the outlet of column 15 and is first introduced into BID 16.

[0031] As shown by the bold arrow in FIG. 2 , a plasma generation gas is supplied at a predetermined flow rate to the first gas flow path 104 of the BID 16 through the gas supply pipe 110. The plasma generation gas is an easily ionized gas, such as helium (or argon, nitrogen, neon, xenon, krypton, or a mixture thereof). The plasma generation gas flows downward through the first gas flow path 104, a portion of which is exhausted to the outside through the bypass exhaust pipe 121, and the remainder flows downward through the second gas flow path 120 as a dilution gas and is exhausted through the sample exhaust pipe 122. Meanwhile, the sample gas passes through the sample introduction pipe 124 and is discharged into the second gas flow path 120 from the outlet at its end. The sample gas is discharged in the opposite direction to the dilution gas, but as shown by the dashed arrow in FIG. 2 , the sample gas is immediately pushed back by the dilution gas, merges with the dilution gas, and continues downward.

[0032] As described above, when the plasma generation gas flows through the first gas flow path 104, the excitation high-voltage AC power supply 109 applies a high-voltage AC voltage to the plasma generation electrodes 106-108. This generates a dielectric barrier discharge in the plasma generation region between the ground electrodes 106 and 108 in the first gas flow path 104, ionizing the plasma generation gas widely and generating plasma (atmospheric pressure non-equilibrium microplasma). Light emitted from this plasma passes through the first gas flow path 104 and the second gas flow path 120 and reaches the region where the sample gas is present, ionizing the sample components in the sample gas. The ions (or electrons) thus generated move toward the collecting electrode 117 due to the action of the electric field formed by the DC voltage applied to the bias electrode 113, and transfer charge to and from the collecting electrode 117.

[0033] As a result, the amount of ions (or electrons) generated from the sample components, i.e., an ion current corresponding to the amount of sample components, is input to the current amplifier 132, which amplifies this and outputs a detection signal. This constantly changing detection signal is sent to the data processing unit 2, where it is converted to digital data at predetermined time intervals by an analog-to-digital converter included in the data acquisition unit 20 and stored. The BID 16 can detect almost all components other than He and Ne. Therefore, detection signals corresponding to each component other than He and Ne contained in the sample gas are obtained.

[0034] After component detection in the BID 16, the sample gas, together with the dilution gas, passes through the sample exhaust pipe 122 and the connecting pipe 18 and is introduced into the FID 17. Although some sample components are lost due to ionization in the BID 16, as described above, only a portion of each component is ionized. Therefore, the sample gas introduced into the FID 17 contains a sufficient amount of the sample components separated in the column 15. In the FID 17, a hydrogen flame is formed from hydrogen and air supplied from a hydrogen supply source and an air supply source (not shown), and the sample gas is introduced into this hydrogen flame to combust the sample components. Ions derived from the sample components generated by this combustion are collected on a collector electrode, yielding a detection signal. This constantly changing detection signal is also sent to the data processing unit 2, where it is converted to digital data at predetermined intervals by an analog-to-digital converter in the data acquisition unit 20 and stored.

[0035] The connecting tube 18 connecting the sample exhaust tube 122 of the BID 16 and the sample gas inlet of the FID 17 is simply a pipe, unlike the column 15, and a sufficient flow rate of gas is supplied to the BID 16. Therefore, the migration speed of the sample components in the connecting tube 18 is sufficiently fast, and the components hardly remain in the connecting tube 18. As a result, the deterioration of separation characteristics (specifically, peak broadening) due to passage through the connecting tube 18 is negligible. Furthermore, the detection signal from the BID 16 and the detection signal from the FID 17 can be considered to correspond to substantially the same retention time.

[0036] In the data processing unit 2, the chromatogram creation unit 21 creates chromatograms corresponding to BID16 and FID17, respectively, based on the data stored in the data collection unit 20 during or after the measurement. The quantitative calculation unit 22 detects peaks corresponding to CO2 and N2O in the chromatogram corresponding to BID16 and calculates the area value of each peak. It also detects a peak corresponding to CH4 in the chromatogram corresponding to FID17 and calculates the area value of that peak. When detecting each peak, the retention time corresponding to each component, which is provided as control information, can be used. Using calibration curves created in advance, the quantitative calculation unit 22 calculates concentrations from the area values ​​of the peaks corresponding to CO2, N2O, and CH4, and outputs the results on the display unit 23. In this way, the measurement device of this embodiment can present the measurement results of the concentrations of CO2, N2O, and CH4 contained in the measurement target gas to the user.

[0037] <Experimental Example> An example of an experiment using the measuring device of the above embodiment will be described. The measurement conditions in this experimental example are as follows. ·Equipment used: Shimadzu Nexis GC-2030 Column used: Micropacked ST Column temperature: 35°C (2 min) → (5°C / min) → 60°C → (40°C / min) → 200°C → (25°C / min) → 250°C → (15°C / min) → 275°C (3 min) Carrier gas column flow rate: 9 mL / min ·Inlet temperature: 100℃ Detector temperature: 280℃ Sample injection volume: 1 mL BID gas flow rate: 50mL / min Connection tube size: Inner diameter 0.5mm, length approximately 1m

[0038] The specific detector connection method was as follows: one end of a metal column of the above size was connected to the outlet (VENT2) of the BID on the back of the device, and the other end of the column was connected to the FID installed in the column oven. The outlet and metal column were connected using an adapter nipple GN-C (P / N: 221-32508), a washer, a nut GF (P / N: 201-30006), and rubber column packing. The metal column was inserted into the outlet by approximately 1 cm and attached to the adapter nipple using a graphite ferrule and nut.

[0039] Figure 6 shows actual measurement examples of chromatograms corresponding to BID and FID. The concentrations of each component are the same as those shown in Figure 5. As is clear from Figure 6, not only are the peaks corresponding to CO2 and N2O clearly observable, but the peak corresponding to CH4, which overlaps with Kr in the results shown in Figure 5, is also well separated from other components and observed with high sensitivity. This allows for highly accurate quantification of these three greenhouse gas components.

[0040] [Measuring device according to another embodiment] 3 is a structural diagram of the essential components of another embodiment of a greenhouse gas measurement device corresponding to the above-mentioned method B. In this measurement device, a two-branch adapter 19 is attached to the end of column 15, one of the branched gas outlets is connected to sample introduction tube 124 of BID 16, and the other gas outlet is connected to a pipe leading to the sample gas inlet of FID 17. The sample gas containing the components separated in column 15 is roughly split into two and supplied to BID 16 and FID 17, respectively. BID 16 and FID 17 perform the above-mentioned detection operations in parallel, and each output a detection signal to data processing unit 2. Note that two-branch adapter 19 does not necessarily need to split the gas into equal amounts; it may also split at some other predetermined ratio.

[0041] FIG. 4 is a structural diagram of the main components of another embodiment of a greenhouse gas measurement device corresponding to the above-described method C. In this measurement device, one end of two columns 15A and 15B is connected to the sample introduction section 10. The other end of one column 15A is connected to the BID 16, and the other end of the other column is connected to the FID 17. The two columns 15A and 15B may be identical. The measurement target gas introduced into the sample introduction section 10 is split into two roughly equal portions and sent to each of the columns 15A and 15B. The sample gas containing the sample components separated in column 15A is introduced into the BID 16, which performs the detection operation described above and outputs a detection signal to the data processing section 2. A chromatogram created based on this detection signal is used to quantify CO2 and N2O. On the other hand, the sample gas containing the sample components separated in column 15B is introduced into the FID 17, which performs the detection operation described above and outputs a detection signal to the data processing section 2. A chromatogram created based on this detection signal is used to quantify CH4.

[0042] It should be noted that the above-described embodiment and measurement examples are merely examples of the present invention, and it goes without saying that appropriate modifications, corrections, additions, etc. made within the spirit of the present invention are also encompassed within the scope of the claims of the present application. For example, the measurement conditions given in the above measurement examples are merely examples, and do not necessarily represent the optimum conditions for quantifying the above-described components, and can be changed as appropriate.

[0043] [Various aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0044] (Item 1) One aspect of the greenhouse gas measurement method according to the present invention is a method for measuring three greenhouse gases contained in the atmosphere, namely, carbon dioxide, methane, and nitrous oxide, using a gas chromatograph, comprising the steps of: a separation step of introducing the atmosphere that may contain the three greenhouse gas components into a gas chromatograph column and separating various components in the atmosphere that contain the components in a time direction; a first detection step of detecting carbon dioxide and nitrous oxide in the gas after the component separation in the separation step using a dielectric barrier discharge ionization detector; a second detection step of detecting methane in the gas after the component separation in the separation step using a hydrogen flame ionization detector; a quantitative processing step of preparing chromatograms based on the detection signals obtained in the first detection step and the second detection step, and quantifying carbon dioxide, nitrous oxide, and methane from peaks observed in the chromatograms; It has.

[0045] (4) Furthermore, one aspect of the greenhouse gas measuring device according to the present invention is a device for measuring three greenhouse gases contained in the atmosphere, namely, carbon dioxide, methane, and nitrous oxide, and a gas chromatograph column for separating various components in the atmosphere, which may contain the three greenhouse gas components, in a time direction; a dielectric barrier discharge ionization detector for detecting carbon dioxide and nitrous oxide in the gas after component separation in the column; a hydrogen flame ionization detector for detecting methane in the gas after detection by the dielectric barrier discharge ionization detector; a quantitative processing unit that creates chromatograms based on the detection signals obtained by the dielectric barrier discharge ionization detector and the hydrogen flame ionization detector, and that quantitatively determines the amounts of carbon dioxide, nitrous oxide, and methane from peaks observed in the chromatograms; Equipped with.

[0046] According to the measurement method described in paragraph 1 and the measurement device described in paragraph 4, carbon dioxide, methane, and nitrous oxide, which are the main greenhouse gases in the atmosphere, can be measured with high sensitivity using a device with a simple and inexpensive configuration that does not involve complex flow path switching, etc. This makes it possible to measure greenhouse gases easily and at low cost.

[0047] (Item 2) In the method for measuring greenhouse gases described in item 1, in the first detection step, the gas after component separation in the separation step can be introduced into the dielectric barrier discharge ionization detector (BID) to detect carbon dioxide and nitrous oxide, respectively, and in the second detection step, the gas after detection in the first detection step can be introduced into the flame ionization detector (FID) to detect methane.

[0048] As mentioned above, the BID is a substantially non-destructive detector, and by connecting the BID and FID in series, the detection performance of each detector can be fully utilized without dividing the sample gas, i.e., without dividing the amount of sample components. As a result, the measurement method described in Section 2 can detect the three major greenhouse gases with high sensitivity and ensure high quantitative accuracy.

[0049] (Item 3) In the method for measuring greenhouse gases described in item 2, the gas detected in the first detection step and introduced into the hydrogen flame ionization detector can be a part of the plasma generating gas introduced into the dielectric barrier discharge ionization detector for plasma generation that contains components in the sample gas introduced into the dielectric barrier discharge ionization detector from the outlet of the column.

[0050] In BID, plasma is generated from a plasma generation gas such as helium. After plasma generation, a portion of the gas is exhausted, and the remaining gas is mixed with a sample gas to detect the sample components. The detected gas is then used for detection of the sample components in the second detection step. Therefore, the concentration of the sample components in the gas used for detection in the second detection step is not lowered more than necessary, and CH4 can be sufficiently detected by the flame ionization detector even when the concentration of CH4 in the air being measured is low. This allows CH4 to be quantified with high accuracy. [Explanation of symbols]

[0051] 1...Gas chromatograph (GC) measurement section 10...Sample introduction section 11...Gas-tight syringe 12...Flow controller 13...Column oven 14...Heater 15, 15A, 15B...Column 16...Dielectric Barrier Discharge Ionization Detector (BID) 17...Flame ionization detector (FID) 18...Connecting pipe 19...2-branch adapter 2...Data processing unit 20...Data collection section 21...Chromatogram creation section 22...Quantitative calculation section 23...Display section 3...Control unit 30...Control information storage unit 101…Discharge part 102...charge collector 103...Ion current detection unit 104...First gas flow path 105...Dielectric cylindrical tube 106...Upstream ground electrode 107...High voltage electrode 108…Downstream ground electrode 109...High voltage AC power supply for excitation 110...Gas supply pipe 111...connecting member 112...First insulating member 113...Bias electrode 114...Second insulating member 115...Additional electrode 116...Third insulating member 117...Collecting electrode 118...Fourth insulating member 119...Pipe end components 120...Second gas flow path 121...Bypass exhaust pipe 122...Sample exhaust pipe 123...Seal part 124...Sample introduction tube 131... DC power supply for bias electrode 132...Current amplifier 133... DC power supply for collecting electrode

Claims

1. A method for measuring three greenhouse gases, carbon dioxide, methane, and nitrous oxide, contained in the atmosphere using a gas chromatograph, comprising: a separation step of introducing the atmosphere that may contain the three greenhouse gas components into a column of a gas chromatograph and separating various components in the atmosphere that contain the three greenhouse gas components in a time direction; a first detection step of introducing the gas separated in the separation step into a dielectric barrier discharge ionization detector and detecting carbon dioxide and nitrous oxide in the gas; a second detection step of introducing the gas detected in the first detection step into the hydrogen flame ionization detector to detect methane in the gas; a quantitative processing step of preparing chromatograms based on the detection signals obtained in the first detection step and the second detection step, and quantifying carbon dioxide, nitrous oxide, and methane from peaks observed in the chromatograms; A method for measuring greenhouse gases.

2. 2. The method for measuring greenhouse gases according to claim 1, wherein the gas detected in the first detection step and introduced into the hydrogen flame ionization detector contains components in the sample gas introduced into the dielectric barrier discharge ionization detector from an outlet of the column in addition to a portion of the plasma generating gas introduced into the dielectric barrier discharge ionization detector for plasma generation.

3. An apparatus for measuring three greenhouse gases, namely, carbon dioxide, methane, and nitrous oxide, contained in the atmosphere, a gas chromatograph column for separating various atmospheric components, which may include the three greenhouse gas components, in a time direction; a dielectric barrier discharge ionization detector for detecting carbon dioxide and nitrous oxide in the gas after component separation in the column; a hydrogen flame ionization detector for detecting methane in the gas after detection by the dielectric barrier discharge ionization detector; a quantitative processing unit that creates chromatograms based on the detection signals obtained by the dielectric barrier discharge ionization detector and the hydrogen flame ionization detector, and that quantitatively determines the amounts of carbon dioxide, nitrous oxide, and methane from peaks observed in the chromatograms; A greenhouse gas measuring device comprising:

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