CN103105366B - CO2 carbon isotope infrared spectrum detection method and device - Google Patents

Abstract

The invention discloses a CO ₂ carbon isotope infrared spectrum detection method and device. The device adopts a reflection pool, an infrared light source, an off-axis parabolic reflector, an interferometer, an infrared detector connected with a computer, and an input gas containing CO ₂ to be measured. The input gas path of the gas to be measured and the standard gas input gas path of the standard CO gas with a known δ ¹³ CO ₂ value, the method of the present invention obtains the δ ¹³ CO ₂ value of the gas to be measured according to the infrared spectrum obtained by _the infrared detector .

Description

CO2 carbon isotope infrared spectrum detection method and device

technical field

    The invention relates to the field of environmental monitoring technology and analysis and optical technology, in particular to a _CO2 carbon isotope infrared spectrum detection device.

Background technique

CO ₂ is one of the most important greenhouse gases in the atmosphere. Because different isotopes have different physical, chemical, and biological change processes, the analysis of the carbon isotope ratio of CO ₂ is conducive to determining the source and sink of carbon elements and providing a basis for the global carbon emission budget. data support. In recent years, CO ₂ gas carbon isotope ratio detection technology has been widely used in many research fields. For example: in the fields of environmental science and ecosystem science, most energy conversion processes in nature are accompanied by the production of CO ₂ , but different carbon isotopes reflect different reaction processes, revealing the differences between natural factors such as soil and plants and various human activities. Influence; in the study of volcanic eruption prediction, the gas released from the crust can react with rocks or other liquids passing through the path on the surface, therefore, the change of δ ¹³ CO ₂ value can be used as an effective indicator for judging the enhancement of volcanic activity and volcanic eruption prediction; in medicine In the field of diagnosis, gas isotope detection can also be used as a non-invasive medical diagnosis. The isotope ratio of CO ₂ is considered as a marker for the presence of Helicobacter pylori (Nobel Prize in Medicine or Physiology in 2005), peptic ulcer and gastric cancer are related to this bacterium Therefore, diseases such as peptic ulcer and gastric cancer can be diagnosed early by detecting changes in the value of δ ¹³ CO ₂ in exhaled CO ₂ gas.

At present, the traditional method for _CO2 carbon isotope ratio detection is the isotope mass spectrometry (IRMS) method. The basic principle of measuring isotopes by isotope mass spectrometry is to distinguish isotope molecules according to the different curved paths caused by different molecular masses. However, this method cannot distinguish isomers with the same molecular weight. For example, ¹³ C ¹⁶ O ₂ and ¹² C ¹⁶ O ¹⁷ O with the same molecular weight of 45 cannot be resolved by isotope mass spectrometry. Processing, and the instrument system is huge and the operation is complicated, so it can only be used for laboratory analysis, which has certain limitations, especially not suitable for real-time continuous measurement.

Infrared spectroscopy is a spectral analysis technology that uses the infrared absorption spectrum characteristics of gas molecules to perform qualitative and quantitative gas measurement. It has high measurement accuracy and can realize the advantages of real-time, online, and unattended, and can realize on-site analysis and measurement of _CO2 carbon isotope ratio experiments. , using infrared spectroscopy to analyze the carbon isotope ratio of _CO2 can effectively make up for the defects of traditional detection techniques.

Contents of the invention

The object of the present invention is to provide a CO ₂ carbon isotope infrared spectrum detection device to solve the defect that the traditional CO ₂ carbon isotope ratio detection technology cannot realize real-time and online detection.

In order to achieve the above object, the technical scheme adopted in the present invention is:

The CO ₂ carbon isotope infrared spectrum detection device is characterized in that it includes a reflective pool, an infrared light source, an off-axis parabolic reflector, and an interferometer are arranged at the light entrance of the reflective pool, and an infrared detector connected to a computer is arranged at the light exit of the reflective pool The air inlet of the reflective cell is connected to the test gas input circuit for inputting the test gas containing CO ₂ gas and the standard gas input circuit for inputting the standard CO ₂ gas with known δ ¹³ CO ₂ value through the three-way valve. The infrared light source radiates infrared light with continuous infrared light waves. The infrared light is sequentially collimated by an off-axis parabolic reflector and modulated by an interferometer, and then enters the reflective pool from the light entrance of the reflective pool. The light outlet of the pool emits to the infrared detector.

The _CO2 carbon isotope infrared spectrum detection device is characterized in that: the input gas path of the gas to be tested includes a gas sampling port to be tested, a dust filter, a Dewar tank equipped with liquid nitrogen, Nafion tube, drying tube with HE-3 type desiccant, gas flow meter, the gas to be tested enters the gas input path from the gas sampling port to be tested, and then passes through the filter to filter out dust, and the Dewar tank for a Stage drying, Nafion tube for secondary drying, drying tube equipped with HE-3 desiccant for tertiary drying, gas flowmeter metered and sent to the reflection pool through the three-way valve.

The standard gas input gas path includes a standard gas inlet and a gas flowmeter connected through the pipeline in turn. The standard gas enters the standard gas input gas path from the standard gas inlet, and then passes through the three-way valve after being measured by the gas flowmeter. into the reflecting pool.

The _CO2 carbon isotope infrared spectrum detection device is characterized in that: the three-way valve has valve ports in three directions a, b and c, and the valve port in direction a of the three-way valve is connected with the air inlet of the reflection pool, and the three-way valve The valve port in the direction b of the one-way valve is connected to the input gas path of the standard gas, the valve port in the direction c of the three-way valve is connected to the input gas path of the gas to be tested, and the valve port in the direction a of the three-way valve is normally open; , the three-way valve ab direction valve port is ventilated, and the ac direction valve port is closed.

The CO _carbon isotope infrared spectrum detection device is characterized in that: the gas outlet of the reflective pool is communicated with the Nafion tube through a flow control valve, and the dry gas discharged from the reflective pool is sent into the Nafion tube through the flow control valve, as the Nafion tube. Blowback gas.

The _CO2 carbon isotope infrared spectrum detection device is characterized in that: the infrared light source, infrared detector, and interferometer constitute a Fourier transform infrared spectrometer, wherein the infrared light source adopts a silicon carbide rod heating element, and the infrared detector adopts antimony The indium detector, the interferometer is a Michelson interferometer; the Fourier transform infrared spectrometer and the reflective cell are placed in a sealed box together, and the sealed box is connected with a purge port, and the sealed box is used in the process of collecting spectra with 0.5l/ The min flow rate is used to purge high-purity nitrogen in real time.

The CO _carbon isotope infrared spectrum detection device is characterized in that it also includes a pressure monitoring system, a temperature monitoring system, and a temperature control system, wherein:

The pressure monitoring system includes a high-precision pressure sensing probe and pressure display and recording software set in the computer. The pressure sensing probe is placed in the reflection pool, and the data line of the pressure sensing probe is connected to the computer to record the pressure data in the reflection pool in real time. And monitor the change of pressure in the reflection pool with time, the pressure accuracy can reach ±1mb;

The temperature monitoring system includes a high-precision temperature sensing probe and temperature display and recording software set in the computer. The temperature sensing probe is placed in the reflection pool, and the data line of the temperature sensing probe is connected to the computer to record the temperature data in the reflection pool in real time. And monitor the temperature change with time in the reflecting pool, the temperature accuracy is up to ±0.01℃;

The temperature control system includes a heating plate, a temperature feedback control circuit, a pt100 temperature probe and a temperature display head. The heating plate is surrounded by the inner wall of the reflecting pool, and the pt100 temperature probe is wrapped inside the heating plate to monitor the surface temperature of the reflecting pool in real time and preheat the heating plate. The temperature is set to 28°C, the temperature feedback control circuit controls the heating plate on and off according to the temperature monitored by pt100, the pt100 temperature probe and the heating plate are connected to the temperature control box, the temperature display head is installed in the control box, and the temperature display head is displayed in real time Set heating temperature and actual temperature monitored by pt100.

The CO _carbon isotope infrared spectrum detection method of the described device is characterized in that: first pump the reflective pool into a fixed low pressure, then fill the reflective pool with high-purity nitrogen to 1013 mb through the standard gas input gas path, and repeat the above process 3 times After the high-purity nitrogen gas in the reflection pool is kept at a constant pressure of 1013 mb and a constant temperature of 28 ° C, the infrared light source is used to radiate infrared light to the reflection pool, and the infrared detector is used to collect the spectrum of high-purity nitrogen gas as the background spectrum, which is used as the background of quantitative analysis;

When the background spectrum is collected, the reflection cell is pumped to a fixed low pressure, and then the standard CO ₂ standard gas with a known δ ¹³ CO ₂ value is filled to 1013mb through the standard gas input gas path, and the above process is repeated 3 times until the standard gas in the reflection cell After the CO ₂ gas is kept at a constant pressure of 1013mb and a constant temperature of 28°C, the infrared light source is used to radiate infrared light to the reflection pool, and the standard CO ₂ gas spectrum is collected by an infrared detector. The standard CO 2 gas spectrum is retrieved from the background spectrum and the standard CO ₂ gas spectrum. The δ ¹³ CO ₂ inversion value of CO ₂ gas, the calibration coefficient is obtained by comparing the inversion δ ¹³ CO ₂ inversion value with the actual δ ¹³ CO ₂ value of the standard CO ₂ gas, as the basis for the calibration of the gas to be measured below;

Finally, the gas to be tested is filled into the reflective cell through the input gas path of the gas to be tested, after the constant pressure of CO ₂ to 1013mb and the constant temperature of 28°C, the infrared light source is used to radiate infrared light to the reflective pool, and the infrared detector is used to collect the infrared spectrum of the gas to be tested , the δ ¹³ CO ₂ inversion value of the gas to be measured is obtained from the inversion of the background spectrum and the infrared spectrum of the gas to be measured, and the δ ¹³ CO ₂ inversion value of the gas to be measured is corrected by combining the calibration coefficient to obtain the δ ¹³ CO 2 of the gas to be measured ₂ measured values.

The _CO2 carbon isotope infrared spectrum detection method is characterized in that: the infrared light modulated by the interferometer forms an interference signal, the infrared light passes through the reflective cell, and the spectrum obtained by Fourier transform of the interference signal characterizes the gas in the reflective cell absorption characteristics.

The CO ₂ carbon isotope infrared spectrum detection method is characterized in that ¹² CO ₂ and ¹³ CO ₂ are treated as two independent components in the quantitative inversion of the CO ₂ carbon isotope ratio.

The invention can realize the real-time, on-line and unattended measurement of the carbon isotope ratio of CO ₂ , which broadens the scope of the application field of the infrared spectrometry.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Detailed ways

The CO ₂ carbon isotope infrared spectrum detection device includes a reflection pool, an infrared light source, an off-axis parabolic reflector, and an interferometer are arranged at the light entrance of the reflection pool, an infrared detector connected to a computer is arranged at the light exit of the reflection pool, and the reflection pool The air inlet is connected to the test gas input gas path containing CO ₂ gas to be tested through the three-way valve and the standard gas input gas path to input the standard CO ₂ gas with known δ ¹³ CO ₂ value. The infrared light source radiation has The infrared light of the continuous infrared light wave, the infrared light is collimated by the off-axis parabolic reflector and modulated by the interferometer, enters the reflective pool from the light entrance of the reflective pool, and exits from the light exit of the reflective pool after multiple reciprocating reflections in the reflective pool to the infrared detector.

The input gas path of the gas to be tested includes the sampling port of the gas to be tested, a dust filter, a Dewar tank filled with liquid nitrogen, a Nafion tube, a drying tube filled with a HE-3 desiccant, and a gas flowmeter, which are connected sequentially through the pipeline. , the gas to be tested enters the input gas path of the gas to be tested from the sampling port of the gas to be tested, and then passes through the filter to filter out dust, the Dewar tank is used for primary drying, the Nafion tube is used for secondary drying, and HE-3 desiccant is installed The drying pipe is subjected to three-stage drying, and the gas flow meter measures it and sends it into the reflection pool through the three-way valve.

The standard gas input gas path includes the standard gas inlet and the gas flowmeter connected through the pipeline in turn. The standard gas enters the standard gas input gas path from the standard gas inlet, and then is sent through the three-way valve after being measured by the gas flowmeter. in the reflecting pool.

The three-way valve has valve ports in three directions a, b, and c. The valve port in the direction a of the three-way valve is connected to the air inlet of the reflection pool. The direction valve port is connected to the input gas path of the gas to be tested, and the three-way valve a direction valve port is normally open; when the inlet air of the reflection pool is standard gas, the gas path of the three-way valve a-b direction valve port is ventilated, and the a-c direction valve port gas path is closed; When the inlet air of the reflecting pool is the gas to be tested, the gas port of the three-way valve a-b direction valve port is closed, and the gas path of the a-c direction valve port is ventilated.

The gas outlet of the reflection pool is connected with the Nafion tube through the flow control valve, and the dry gas discharged from the reflection pool is sent into the Nafion tube through the flow control valve as the blowback gas of the Nafion tube.

Infrared light source, infrared detector, and interferometer constitute a Fourier transform infrared spectrometer, in which the infrared light source uses a silicon carbide rod heating element, the infrared detector uses an indium antimonide detector, and the interferometer is a Michelson interferometer; the Fourier transform infrared spectrometer It is placed in a sealed box together with the reflection pool, and the sealed box is connected with a purge port, and the sealed box is purged with high-purity nitrogen gas at a flow rate of 0.5 l/min in real time during the spectrum collection process.

Also includes pressure monitoring system, temperature monitoring system, temperature control system, of which:

The pressure monitoring system includes a high-precision pressure sensing probe and pressure display and recording software set in the computer. The pressure sensing probe is placed in the reflection pool, and the data line of the pressure sensing probe is connected to the computer to record the pressure data in the reflection pool in real time. And monitor the change of pressure in the reflection pool with time, the pressure accuracy can reach ±1mb;

The temperature monitoring system includes a high-precision temperature sensing probe and temperature display and recording software set in the computer. The temperature sensing probe is placed in the reflection pool, and the data line of the temperature sensing probe is connected to the computer to record the temperature data in the reflection pool in real time. And monitor the temperature change with time in the reflecting pool, the temperature accuracy is up to ±0.01℃;

The temperature control system includes a heating plate, a temperature feedback control circuit, a pt100 temperature probe and a temperature display head. The heating plate is surrounded by the inner wall of the reflecting pool, and the pt100 temperature probe is wrapped inside the heating plate to monitor the surface temperature of the reflecting pool in real time and preheat the heating plate. The temperature is set to 28°C, the temperature feedback control circuit controls the heating plate on and off according to the temperature monitored by pt100, the pt100 temperature probe and the heating plate are connected to the temperature control box, the temperature display head is installed in the control box, and the temperature display head is displayed in real time Set heating temperature and actual temperature monitored by pt100.

A CO ₂ carbon isotope infrared spectrum detection method, first pumping the reflective pool to a fixed low pressure, then filling the reflective pool with high-purity nitrogen to 1013 mb through the standard gas input gas path, repeating the above process 3 times, and waiting for high-purity nitrogen in the reflective pool After the nitrogen gas is kept at a constant pressure of 1013mb and a constant temperature of 28°C, the infrared light source is used to radiate infrared light to the reflection pool, and the infrared detector is used to collect the spectrum of high-purity nitrogen gas as the background spectrum, which is used as the background of quantitative analysis;

When the background spectrum is collected, the reflection cell is pumped to a fixed low pressure, and then the standard CO ₂ standard gas with a known δ ¹³ CO ₂ value is filled to 1013mb through the standard gas input gas path, and the above process is repeated 3 times until the standard gas in the reflection cell After the CO ₂ gas is kept at a constant pressure of 1013mb and a constant temperature of 28°C, the infrared light source is used to radiate infrared light to the reflection pool, and the standard CO ₂ gas spectrum is collected by an infrared detector. The standard CO 2 gas spectrum is retrieved from the background spectrum and the standard CO ₂ gas spectrum. The δ ¹³ CO ₂ inversion value of CO ₂ gas, the calibration coefficient is obtained by comparing the inversion δ ¹³ CO ₂ inversion value with the actual δ ¹³ CO ₂ value of the standard CO ₂ gas, as the basis for the calibration of the gas to be measured below;

Finally, the gas to be tested is filled into the reflective cell through the input gas path of the gas to be tested, after the constant pressure of CO ₂ to 1013mb and the constant temperature of 28°C, the infrared light source is used to radiate infrared light to the reflective pool, and the infrared detector is used to collect the infrared spectrum of the gas to be tested , the δ ¹³ CO ₂ inversion value of the gas to be measured is obtained from the inversion of the background spectrum and the infrared spectrum of the gas to be measured, and the δ ¹³ CO ₂ inversion value of the gas to be measured is corrected by combining the calibration coefficient to obtain the δ ¹³ CO 2 of the gas to be measured ₂ measured values.

The infrared light modulated by the interferometer forms an interference signal, and the infrared light passes through the reflection cell, and the spectrum obtained by Fourier transform of the interference signal characterizes the absorption characteristics of the gas in the reflection cell.

¹² CO ₂ and ¹³ CO ₂ are treated as two independent components in the quantitative inversion of CO ₂ carbon isotope ratio.

As shown in Figure 1. The Fourier transform infrared spectrometer 18, detector 15, light source 17 and multiple reflection cell 11 are all placed in the sealed box 13, and the sealed box is purged with high-purity nitrogen at a flow rate of 0.5 l/min in real time during the spectrum collection process to ensure The optical path of the spectrometer in the sealed box does not contain excess water vapor and CO ₂ gas. When the ab direction of the three-way valve 8 is closed and the ac direction is ventilated, the gas to be tested on site is filtered by the filter 2 under the work of the air pump to filter out the dust in the air, and then the gas pipe passes through the Dewar tank 3 Condensation of liquid nitrogen can remove part of the water vapor in the gas to be tested, and the gas to be tested after the primary drying is then passed through the Nafion tube 4 and the drying tube 5 equipped with HE-3 high-efficiency color-changing desiccant for the second and third stages of drying, and then Pass through the gas flow meter 7 and the three-way valve 8 into the multiple reflection sample cell 11 . When the ac direction of the three-way valve 8 is closed and the ab direction is ventilated, the standard gas enters the reflection pool through the gas flow meter 7 and the three-way valve 8 . The CO ₂ carbon isotope infrared spectrum detection device is calibrated once a day. When calibrating, first pump the reflection pool to a fixed low pressure (<1mb), then fill it with high-purity nitrogen to 1013mb, repeat the above process 3 times, and wait until the reflection pool is high-purity. After the nitrogen gas is kept at 1013mb, 28°C constant temperature and pressure, the high-purity nitrogen spectrum is collected as the background spectrum for subsequent quantitative analysis; when the background spectrum is collected, the reflection cell is pumped to a low pressure (<1mb), and then filled into the calibration When the gas reaches 1013mb, repeat the above process 3 times. After the standard gas in the reflection cell is kept at 1013mb and 28°C at a constant temperature and pressure, collect the standard gas spectrum and invert the carbon isotope ratio of the standard gas as the basis for the following gas calibration. In the process of collecting spectra, each spectrum was scanned by 64scans, and ¹² CO ₂ and ¹³ CO ₂ were treated as two independent components in the quantitative inversion of CO ₂ carbon isotope ratio.

Claims (2)

1.CO ₂carbon isotope infrared spectrum pick-up unit, it is characterized in that: comprise reflection tank, reflection tank light inlet place is provided with infrared light supply, off-axis parabolic mirror, interferometer, reflection tank light-emitting window place is provided with the infrared eye be connected with computing machine, and reflection tank air intake opening has access to input containing CO by T-valve ₂the gas input gas circuit to be measured of gas gas to be measured and the known δ of input ¹³cO ₂the standard C O of value ₂the Standard Gases input gas circuit of gas, infrared light supply radiation has the infrared light of continuous infrared waves, infrared light successively through off-axis parabolic mirror collimation, interferometer modulation after enter reflection tank by the light inlet of reflection tank, and in reflection tank through repeatedly after interflection by the outgoing of reflection tank light-emitting window to infrared eye;

Described gas to be measured input gas circuit comprise successively by the gas thief hatch to be measured of pipeline connection, dust filter unit, the Dewar tank that liquid nitrogen is housed, Nafion pipe, drying tube, the gas meter of HE-3 type drying agent are housed, gas to be measured enters gas to be measured input gas circuit from gas thief hatch to be measured, then filter dust through filtrator successively, Dewar tank carries out one-level drying, Nafion pipe carries out secondary drying, be equipped with after the drying tube of HE-3 type drying agent carries out three-stage drying, gas meter metering and sent in reflection tank by T-valve; Described Standard Gases input gas circuit comprises successively by Standard Gases air intake opening, the gas meter of pipeline connection, and Standard Gases from Standard Gases air intake opening Engage of standard gas input gas circuit, then is sent in reflection tank by T-valve after gas meter metering;

Described T-valve has the valve port in a, b, c tri-directions, and T-valve a direction valve port is connected with reflection tank air intake opening, T-valve b direction valve port access Standard Gases input gas circuit, and T-valve c direction valve port accesses gas to be measured input gas circuit, T-valve a direction valve port normal open; When reflection tank air inlet is Standard Gases, ventilate in T-valve a-b direction valve implication road, and a-c direction valve implication road closes; When reflection tank air inlet is gas to be measured, T-valve a-b direction valve implication mouth closes, and ventilates in a-c direction valve implication road;

Described reflection tank gas outlet is communicated with Nafion pipe by flowrate control valve, and the dry gas that reflection tank is discharged sends into Nafion pipe, as the purge gas of Nafion pipe by flowrate control valve;

Described infrared light supply, infrared eye, interferometer form Fourier transform infrared spectrometer, and its mid-infrared light source adopts Globar heating element, and infrared eye adopts indium antimonide detector, and interferometer is Michelson interferometer; Fourier infrared spectrograph and reflection tank are placed in seal box jointly, and described seal box has access to blow valve port, and seal box purges high pure nitrogen in real time with 0.5l/min flow velocity in collection spectroscopy procedure;

Also comprise pressure monitor system, temperature monitoring system, temperature control system, wherein:

Pressure monitor system comprises high-precision pressure sensing probe and arranges pressure display logging software in a computer, pressure sensing probe is placed in reflection tank, the data line of pressure sensing probe is received on computing machine with pressure data in real time record reflection tank, and pressure situation of change in time in monitoring reflection tank, pressure precision reaches ± 1mb;

The Temperature displaying logging software that temperature monitoring system comprises high-precision temperature sensing probe and arranges in a computer, temperature sensing probe is placed in reflection tank, the data line of temperature sensing probe is received on computer with temperature data in real time record reflection tank, and temperature situation of change in time in monitoring reflection tank, temperature accuracy reaches ± and 0.01 DEG C;

Temperature control system comprises heating plate, temperature feedback control circuit, pt100 temp probe and Temperature displaying gauge outfit, heating plate is enclosed in reflection tank inwall, pt100 temp probe wraps in inside heating plate with Real-Time Monitoring reflection tank surface temperature, heating plate pre-heating temperature is set to 28 DEG C, the temperature that temperature feedback control circuit is monitored according to pt100 controls heating plate break-make, pt100 temp probe and the equal cut-in temperature control enclosure of heating plate, Temperature displaying gauge outfit is arranged in control enclosure, Temperature displaying gauge outfit shows the actual temperature arranging heating-up temperature and pt100 monitoring in real time.

2. the CO based on device described in claim 1 ₂carbon isotope infrared spectrum detection method, it is characterized in that: first reflection tank is pumped into fixing low pressure, then in reflection tank, high pure nitrogen is filled with to 1013mb by Standard Gases input gas circuit, repeat above process 3 times, after in pond to be reflected, high pure nitrogen remains on 1013mb constant pressure, 28 DEG C of steady temperatures, utilize infrared light supply to reflection tank irradiating infrared light, and utilize infrared eye to gather high pure nitrogen spectrum spectrum as a setting, as the background of quantitative test;

When having gathered background spectrum, fixing low pressure will be pumped in reflection tank, then be filled with known δ by Standard Gases input gas circuit ¹³cO ₂the standard C O of value ₂standard Gases, to 1013mb, repeats above process 3 times, pond internal standard CO to be reflected ₂gas utilizes infrared light supply to reflection tank irradiating infrared light after remaining on 1013mb constant pressure, 28 DEG C of steady temperatures, and utilizes infrared eye to gather standard C O ₂gaseous spectrum, by background spectrum and standard C O ₂gaseous spectrum inverting obtains standard C O ₂the δ of gas ¹³cO ₂inverting value, by the δ of inverting ¹³cO ₂inverting value and standard C O ₂the δ of gas reality ¹³cO ₂value compares and obtains calibration factor, as the foundation of gas calibration to be measured below;

In reflection tank, gas CO to be measured is filled with finally by gas input gas circuit to be measured ₂to 1013mb constant pressure, 28 DEG C of steady temperatures, utilize infrared light supply to reflection tank irradiating infrared light, and utilize infrared eye to gather gas infrared spectrum to be measured, obtained the δ of gas to be measured by background spectrum and gas infrared spectrum to be measured inverting ¹³cO ₂inverting value, then in conjunction with the δ of calibration factor to gas to be measured ¹³cO ₂inverting value carries out revising the δ obtaining gas to be measured ¹³cO ₂measured value;

Infrared light through interferometer modulation forms interference signal, and infrared light, through reflection tank, carries out by interference signal the Absorption Characteristics that spectrogram that Fourier transform obtains characterizes reflection pool gas;

At CO ₂will in carbon isotope ratio quantitative inversion ¹²cO ₂with ¹³cO ₂as two kinds independently component treat.