JP3014652B2 - Isotope gas spectrometry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The metabolic function of a living body can be measured by administering a drug containing an isotope to a living body and then measuring the change in the isotope concentration or the change in the concentration ratio. Body analysis has been used to diagnose diseases in the medical field. In addition to the fields of medicine, isotope analysis is used for studies of photosynthesis and metabolism of plants, and is used for tracing ecosystems in the field of geochemistry.

[0002] The present invention relates to an isotope gas spectrometry method for measuring the concentration of an isotope gas by focusing on the difference in the light absorption characteristics of the isotopes.

[0003]

2. Description of the Related Art In general, it is known that bacteria other than stress include bacteria called Helicobacter pylori (HP) as a cause of gastric ulcer and gastritis. If HP is present in the patient's stomach, it is necessary to perform eradication treatment by administration of antibiotics or the like. Therefore, it is important to determine whether HP is present in the patient. HP is
It has strong urease activity and breaks down urea into carbon dioxide and ammonia.

[0004] On the other hand, carbon has a mass number of 12 and isotopes having a mass number of 13 and 14 in addition to a carbon atom having a mass number of 12. Among these, the isotope ¹³ C having a mass number of 13 has no radioactivity, Handling is easy because it exists stably. Therefore, after administering urea marked with the isotope ¹³ C to the living body, the concentration of ¹³ CO ₂ in the patient's breath, which is the final metabolite, specifically, the concentration ratio of ¹³ CO ₂ to ¹² CO ₂ is measured. If it can, the existence of the HP can be confirmed.

However, the concentration ratio of ¹³ CO ₂ to ¹² CO ₂ is as large as 1: 100 in nature, and it is difficult to accurately measure the concentration ratio in a patient's breath. Conventionally,
^As a method for determining the concentration ratio between ¹³ CO ₂ and ¹² CO ₂ , a method using infrared spectroscopy is known (Japanese Patent Publication No. Sho 61-42).
No. 219, JP-B-61-42220).

[0006] The method described in JP-B-61-42220 is
Two long and short cells were prepared, and the length of the cell was set so that the absorption of ¹³ CO ₂ in one cell was equal to the absorption of ¹² CO _{2 in} one cell, and the cells were transmitted through the two cells. In this method, light is guided to both cells, and the light intensity at a wavelength that achieves the maximum sensitivity is measured. According to this method, the light absorption ratio at the concentration ratio in the natural world can be set to 1. If the concentration ratio deviates from this, the light absorption ratio deviates by the amount of the deviation. You can see the change in the ratio.

[0007]

In THE INVENTION It is an object of the infrared spectrometry, the breath before administration, ¹² by measuring the absorbance of CO _2, to calculate the ¹² CO ₂ concentration using the calibration curve for ¹² CO _2, ¹³ by measuring the absorbance of CO _2, to calculate the ¹³ CO ₂ concentration using the calibration curve for ¹³ CO _2. The same measurement is performed for the expired air after administration.

At this time, if the CO ₂ concentration is substantially the same for the two types of exhalation, the range in which the calibration curve of ¹² CO _{2 or} the calibration curve of ¹³ CO ₂ is used can be narrowed. Therefore,
The measurement accuracy can be improved by limiting the range in which the calibration curve is used. In order to make the CO ₂ concentration equal, either exhaled breath must be diluted, but the gas to be diluted (hereinafter referred to as “diluent gas”) usually does not have absorption in the infrared region such as nitrogen gas. It is conceivable to use a gas (Japanese Patent Application Laid-Open No. 8-58, a prior application of the present application).
In the embodiment of the invention of No. 052, nitrogen gas is used as a diluent gas).

However, in this dilution method, the diluted call
Since diluent gas is mixed in air,
The composition ratio of the constituent gas with the exhaled air is different.
As a result, the difference between the component ratios¹³CO_Twoconcentration
And¹³CO_TwoWhen¹²CO _TwoAffect the measurement of concentration ratio with
This causes an error in the measured value.

Accordingly, the present invention provides a method of introducing a gas to be measured containing a plurality of component gases into a cell, and diluting the components of the expired gas so as not to change the composition of the component gases when performing spectroscopic measurement. It is an object of the present invention to realize an isotope gas spectrometry method capable of precisely measuring the gas.

[0011]

According to a first aspect of the present invention, there is provided an isotope gas spectrometry method for achieving the above object, wherein one type of gas to be measured is used for two types of gases to be measured collected from one sample. CO ₂ CO ₂ concentration of the other gas to be measured
Is higher than the concentration, one of the measurement gas until the CO ₂ concentration of one of the measurement gas is equal to the CO ₂ concentration of the other gas to be measured is diluted with air (atmosphere), of the measurement gas a method for measuring the concentration ratio ¹³ CO ^_2/12 CO _2.

According to this method, since two types of exhalation can be measured under the condition that the CO ₂ concentration is equal, the range of the calibration curve to be used can be limited.
Moreover, since air is used as the diluent gas, the composition of the expiratory component gas is not changed by the dilution. As a result, measurement accuracy can be improved. The method according to claim 2 or 3, wherein each of the single cells is filled with the first type of gas to be measured, the light quantity is measured, and after discharging, the light quantity is measured with the second type of gas to be measured. 2 shows a specific procedure of the isotope gas spectroscopic measurement method according to claim 1 on the assumption that the measurement is performed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, after a urea diagnostic agent marked with isotope ¹³ C is administered to humans, ¹³ CO _{2 in} exhaled breath
An embodiment of the present invention for performing spectral measurement of the concentration ratio,
This will be described in detail with reference to the accompanying drawings. I. Breath test First, the breath of the patient before administration of the urea diagnostic agent is collected in a breath bag. The capacity of the exhalation bag is about 250 ml. Thereafter, a urea diagnostic agent was orally administered and 10-1
After 5 minutes, exhale is collected in another exhalation bag in the same manner as before administration.

The exhalation bags before and after administration are respectively set in predetermined nozzles of an isotope gas spectrometer, and the following automatic control is performed. II. FIG. 1 is a block diagram showing the overall configuration of an isotope gas spectrometer. The exhalation bag that collects the exhaled air after administration (hereinafter referred to as “sample gas”) and the exhalation bag that collects the exhaled air before administration (hereinafter referred to as “base gas”) are each set in a nozzle. Breath bags were collected based gas is led to the valve V ₃ through the resin or metal pipe (hereinafter simply referred to as "pipe"), breath bags were collected sample gas has led to the valve V ₂ through a pipe.

On the other hand, a reference gas (any gas having no absorption in the wavelength range to be measured, for example, nitrogen gas) is supplied from a gas cylinder. Reference gas is pressure relief valve 31, valve V ₀ , regulator 3
2. Through the flow meter 33, one enters the reference cell 11c through the needle valve 35, and the other
_1. Enter the first sample cell 11a for measuring the absorption of ¹² CO ₂ through the check valve 36.

Further, the valve V ₁ and the first sample cell 1
1a, a gas injector 21 (capacity: 70 cc) for quantitatively injecting a sample gas or a base gas is provided.
It is coupled via a three-way valve V _4. The gas injector 21 is of a shape such as a syringe having a piston and cylinder, the driving of Bisuton includes a motor M _1, a feed screw connected to the motor M _1, is fixed to the piston a the nut It is done by cooperation.

As shown in FIG. 1, the cell chamber 11 contains ¹² CO 2.
Short first sample cell 11 for measuring the absorption of ₂
a, comprising a long second sample cell 11b for measuring the absorption of ¹³ CO ₂ and a reference cell 11c for flowing a reference gas, the first sample cell 11a and the second sample cell 11b are in communication with each other, Cell 1
The gas led to the first sample cell 11a
b and is exhausted. Further, a reference gas is guided to the reference cell 11c. After passing through the reference cell 11c, one of the reference gases passes through the case 10 housing the cell chamber 11, and the other passes through the infrared light source device L. Exhausted. The length of the first sample cell 11a is specifically 13 m
m, the length of the second sample cell 11b is specifically 250 mm, and the length of the reference cell 11c is specifically 236 mm.

An exhaust pipe led from the second sample cell 11b is provided with an O ₂ sensor 18 and a humidity sensor 19. As the O ₂ sensor 18, a commercially available oxygen sensor can be used. For example, a solid electrolyte gas sensor such as a zirconia sensor or an electrochemical gas sensor such as a galvanic cell type sensor can be used. Humidity sensor 19
A commercially available humidity sensor can be used, for example, a sensor using a porous ceramic or a polymer resistor.

The infrared light source device L has two waveguides 23a and 23b for irradiating infrared rays. The method of generating infrared rays may be any method, for example, a ceramic heater (surface temperature of 450 ° C.) or the like can be used. Also,
A rotating chopper 22 is provided to cut off and pass infrared rays at a constant period. Among the infrared rays emitted from the infrared light source device L, an optical path formed by a light passing through the first sample cell 11a and the reference cell 11c is referred to as a “first light path”, and an optical path formed by a light passing through the second sample cell 11b. Is referred to as a “second optical path”.

Symbol D detects infrared light passing through the cell.
FIG. The infrared detector D is
A first wavelength filter 24a placed in a first optical path and a first wavelength filter 24a;
Detecting element 25a, the second wavelength filter placed in the second optical path.
It has a filter 24b and a second detection element 25b. No.
One wavelength filter 24a is¹²CO_TwoMeasuring absorption
For this reason, it passes infrared light with a wavelength of about 4280 nm (bandwidth about
20 nm), the second wavelength filter 24b ¹³CO_Twoof
Pass infrared light at a wavelength of about 4412 nm to measure absorption.
(Bandwidth about 50 nm). First
Detection element 25a and second detection element 25b detect infrared rays.
Any element can be used as long as the element emits, for example, PbSe.
Such a semiconductor infrared sensor is used.

The first wavelength filter 24a and the first detection element 25a are contained in a package 26a filled with an inert gas such as Ar, and the second wavelength filter 24a.
b, the second detection element 25b is also contained in a package 26b filled with an inert gas. The entire infrared detecting device D is maintained at a constant temperature (25 ° C.) by a heater and a Peltier element 27, and the packages 26a, 26b
The part of the detection element in the above is maintained at 0 ° C. by the Peltier element.

The cell chamber 11 is itself made of stainless steel, and is vertically or horizontally sandwiched by the heater 13. The cell chamber 11 is divided into two stages, one of which has a first sample cell 11a and a reference cell 11c, and the other of which has a second sample cell 11b. First sample cell 11a and reference cell 1
1c, the first optical path passes in series, and the second sample cell 1
A second optical path passes through 1b. Symbols 15, 16, 1
Reference numeral 7 denotes a sapphire transmission window that transmits infrared rays.

The cell chamber 11 is controlled by a heater 13 so as to be maintained at a constant temperature (40 ° C.). III. Measurement procedure In the measurement, the CO ₂ concentration of the base gas and the C
O ₂ in order to substantially coincide with the concentration, the first preliminary measurement, the CO ₂ concentration of the base gas, the sample gas CO ₂
The concentration was measured, in the measurement, is higher than the CO ₂ concentration of the sample gas CO ₂ concentration was pre-determined pre measured based gas, the base gas CO
_{After 2} concentration were diluted based gas to be equal to the CO ₂ concentration of the sample gas, to measure the concentration of the base gas, and then measuring the concentration of the sample gas.

In this measurement, if the pre-measured CO ₂ concentration of the base gas is measured, the C ₂ of the pre-measured sample gas is measured.
If it is lower than the O ₂ concentration, the concentration of the base gas is measured as it is, and the CO ₂ concentration of the sample gas is
After diluting the sample gas until the concentration becomes equal to ₂ , the CO ₂ concentration of the sample gas is measured. Measurement is: reference gas measurement → base gas preliminary measurement → reference gas measurement → sample gas preliminary measurement → reference gas measurement →
Perform the following procedure: base gas measurement → reference gas measurement → sample gas measurement → reference gas measurement → ‥‥. III-1. Base gas preliminary measurement In the gas channel and cell chamber 11 of the isotope gas spectrometer,
Gas flow path and cell chamber 1 by flowing a clean reference gas
In addition to the washing of step 1, the reference light quantity is measured.

[0025] Specifically, as shown in FIG. 2 (a), it opens the three-way valve V ₄ in the cell chamber 11 side, opens the valve V _1,
Suck reference gas in the gas injector 21, it discharges the reference gas in the gas injector 21 closes the valve V _1, the first sample cell 11a and the second sample cell 1
Wash 1b. In addition, the reference gas is always allowed to flow through the reference cell 11c.

Next, as shown in FIG. 2 (b), valve V ₃
Is opened and the base gas is supplied from the expiration bag to the gas injector 21.
And the base gas is mechanically pushed out at a constant flow rate using the gas injector 21. During this time, the light quantity of the base gas is measured by the detection element 25a, and the CO ₂ concentration is determined from the absorbance using a calibration curve. III-2. Preliminary measurement of sample gas In the gas channel and cell chamber 11 of the isotope gas spectrometer,
Gas flow path and cell chamber 1 by flowing a clean reference gas
In addition to the washing of step 1, the reference light quantity is measured.

More specifically, as shown in FIG. 2C, the valve V ₁ is opened, the gas injector 21 sucks in the reference gas, the valve V ₁ is closed, and the gas injector 21 discharges the reference gas. , The first sample cell 11a and the second
The sample cell 11b is washed. Next, as shown in FIG. 2 (d), opening the valve V _2, from the breath bag, the sample gas suction gas injector 21, pushes mechanically the sample gas at a constant flow rate using a gas injector 21 . During this time, the light intensity of the sample gas is measured by the detection element 25a, and the CO ₂ concentration is determined using the calibration curve based on the absorbance. III-3. Reference Measurement Next, the reference gas is flowed while changing the gas flow path, and the gas flow path and the cell chamber 11 are cleaned. After a lapse of about 30 seconds, the light quantity is measured by the respective detection elements 25a and 25b.

More specifically, as shown in FIG. 3A, the valve V ₁ is opened, the reference gas is sucked in by the gas injector 21, the valve V ₁ is closed, and the reference gas is discharged by the gas injector 21. , The first sample cell 11a and the second
The sample cell 11b is washed. During this time, the detection element 25
a, the light quantity of the reference gas is measured by the detection element 25b. The amount of light obtained by the first detection element 25a is ¹² R
_1, the amount of light obtained by the second detection element 25b are the ¹³ R _1. III-4. Base gas measurement In “III-1. Base gas preliminary measurement”, the CO ₂ concentration of the base gas obtained by the first detection element 25a and “II
I-2. Comparing the CO ₂ concentration of the sample gas obtained by the first detection element 25a in a sample gas preliminary measurement ", when CO ₂ concentration of the base gas is darker than the CO ₂ concentration of the sample gas, in the gas injector 21 And base gas C
After diluting the base gas with air until the O ₂ concentration becomes equal to the CO ₂ concentration of the sample gas, the light quantity of the base gas is measured.

Specifically, as shown in FIG.
Valve V_FourIs opened to the atmosphere side, and the air is
Inhale a fixed amount. Next, as shown in FIG.
Bu V _FourIs opened to the cell chamber side and the valve V_ThreeOpen the gas injection
The base gas is sucked in the vessel 21 and mixed with air. this
So that the two types of exhaled CO_Twoconcentration
Can be made almost the same,¹²CO_TwoCalibration curve¹³CO_Two
The range of using the calibration curve can be narrowed.

[0030] In the measurement procedure of this embodiment, there are means at the almost the same concentration of CO ₂ for two exhalation, the CO ₂ concentration as described in Japanese Patent KOKOKU 4-12414 It should be noted that it is not always necessary to adopt a procedure for maintaining a constant value at all times. This is because if the CO ₂ concentration in the base gas and the sample gas can be made the same, the purpose of narrowing the range in which the calibration curve is used can be sufficiently achieved. According to the actual measurement, the CO ₂ concentration of the base gas and the sample gas varies from 1% to 5%, so that it is very troublesome to always keep the CO ₂ concentration at a constant value.

[0031] If the CO ₂ concentration of the base gas is less than the CO ₂ concentration of the sample gas is directly measuring the base gas without dilution base gas. The measurement is performed by mechanically extruding the base gas at a constant flow rate by using the gas injector 21 and during this time, by the respective detection elements 25a and 25b. Thus, the first detection element 25a ¹² B and the resulting amount of light, the amount of light obtained by the second detection element 25b are the ¹³ B. III-5. Reference Measurement As shown in FIG. 3D, the gas flow path and the cell are washed again, and the light quantity of the reference gas is measured.

As described above, the light amount ¹² R ₂ obtained by the first detection element 25 a and the light amount ¹³ R ₂ obtained by the second detection element 25 _b are written. III-6. Sample gas measurement When the base gas is diluted in "III-4. Base gas measurement", as shown in FIG. Is mechanically extruded at a constant flow rate, and during this time, the light amounts are measured by the respective detection elements 25a and 25b.

[0033] If the "III -4. Base gas measurement" Undiluted the base gas in until the CO ₂ concentration and the ratio is equal to the CO ₂ concentration and the base gas of the sample gas in the gas injector 21 After diluting the sample gas with air,
The light quantity of the sample gas is measured by the respective detection elements 25a and 25b. In this manner, the light quantity of ¹² S obtained in the first detection element 25a, the amount of light obtained by the second detection element 25b are the ¹³ S. III-7. Reference gas measurement The gas flow path and the cell are washed again, and the light quantity of the reference gas is measured.

The amount of light ¹² R ₃ obtained by the first detection element 25 a and the amount of light ¹³ R ₃ obtained by the second detection element 25 b are written as described above. IV. Data processing IV-1. Calculating the absorbance of the base gas First, the amount of transmitted light ¹² R ₁ of the reference gas obtained in the measuring procedure, ¹³ R _1, the amount of transmitted light ¹² B of the base gas,
¹³ B, the absorbance of ¹² CO ₂ in the base gas, ¹² Abs (B) using the transmitted light amounts of ¹² R ₂ and ¹³ R ₂ of the reference gas
And the absorbance of ¹³ CO ₂ , ¹³ Abs (B).

[0035] Here, ¹² CO ₂ absorbance ¹² Abs (B) is, ¹² Abs (B) = - calculated in log _{^{[2 12 B / (12 R 1}} + 12 R 2) ], ¹³ CO ₂ absorbance ¹³ determined by log _{^{[2 13 B / (13 R 1}} + 13 R 2) ] ^{- abs (B), 13 abs} (B) =.

As described above, when calculating the absorbance,
The average value (R₁+ R
_Two) / 2, the average value and the value obtained by base gas measurement.
Since the absorbance is calculated using the amount of light
The effects of the
can do. Therefore, when starting up the equipment,
Don't wait for it to reach full thermal equilibrium (usually a few hours)
The measurement can be started immediately. IV-2. Calculation of absorbance of sample gas Next, the transmission of the reference gas obtained by the above measurement procedure
Light intensity¹²R_Two,¹³R_TwoAnd the amount of transmitted sample gas¹²S,¹³
S, amount of transmitted reference gas¹²R_Three,¹³R _Three Using
In the sample gas¹²CO_Two Absorbance of¹²Abs (S)
When,¹³CO_Two Absorbance of¹³Abs (S).

[0037] Here, ¹² CO ₂ absorbance ¹² Abs (S) is, ¹² Abs (S) = - calculated in log _{^{[2 12 S / (12 R 2}} + 12 R 3) ], ¹³ CO ₂ absorbance ¹³ abs (S) is, ¹³ abs (S) = - is determined by the log _{^{[2 13 S (13 R 2 +}} 13 R 3) ].

As described above, when calculating the absorbance, the average value of the light amounts of the reference measurements performed before and after is taken, and the absorbance is calculated using the average value and the light amount obtained by the sample gas measurement. Therefore, the influence of the drift can be offset. IV-3. Calculation of Concentration The concentration of ¹² CO _{2 and} the concentration of ¹³ CO ₂ are determined using a calibration curve.

A calibration curve is created using a gas to be measured having a known ¹² CO ₂ concentration and a gas to be measured having a known ¹³ CO ₂ concentration. To create a calibration curve, change the ¹² CO ₂ concentration in the range of about 0% to 6% and measure the absorbance of ¹³ CO ₂ . The horizontal axis is ¹² CO ₂ concentration, and the vertical axis is ¹² C
Take the O ₂ absorbance, plot and determine the curve using least squares. Since the curve approximated by the quadratic equation has a relatively small error curve, the calibration curve approximated by the quadratic equation is employed in the present embodiment.

Further, the concentration of ¹³ CO _{2 is set} to 0.00% to 0.0%.
Change the absorbance at about 7% and measure the absorbance of ¹² CO ₂ . The horizontal axis is taken as ¹³ CO ₂ concentration, the vertical axis is taken as ¹³ CO ₂ absorbance, plotted, and the curve is determined using the least squares method. Since the curve approximated by the quadratic equation has a relatively small error curve, the calibration curve approximated by the quadratic equation is employed in the present embodiment.

Strictly speaking, the gas containing ¹² CO ₂ and the gas containing ¹³ CO ₂ are measured independently, and the gas containing ¹² CO ₂ and ¹³ CO ₂ is mixed. , The absorbance of ¹³ CO ₂ will be different. This is because the wavelength filter used has a bandwidth and the absorption spectrum of ¹² CO _{2 and} the absorption spectrum of ¹³ CO ₂ partially overlap. In this measurement,
^Since a gas in which ¹² CO ₂ and ¹³ CO ₂ are mixed is to be measured, it is necessary to correct the overlap when determining a calibration curve. In this measurement, a calibration curve in which the overlap of the absorption spectra is partially corrected is actually used.

The base gas calculated using the calibration curve
In¹²CO_TwoThe concentration of¹²Conc (B) for base gas
Put¹³CO_TwoThe concentration of¹³Conc (B), sample gas
Kick ¹²CO_TwoThe concentration of¹²Conc (S) in sample gas
To¹³CO_TwoThe concentration of¹³Write Conc (S). IV-4. Calculation of concentration ratio¹³ CO_Two When¹²CO_Two The concentration ratio is determined. For base gas
Concentration ratio¹³ Conc (B) /¹²Conc (B) The concentration ratio in the sample gas is¹³ Conc (S) /¹²Required by Conc (S).

The concentration ratio is:¹³Conc (B) / [¹²Conc
(B) +¹³Conc (B)],¹³Conc (S) / [ ¹²Conc (S) +¹³Con
c (S)].¹²CO_Two The concentration of¹³
CO_TwoAre much higher than
This is because the same value is obtained. IV-5.¹³Determination of change in C Comparison between sample gas and base gas¹³The change in C is
It is obtained by the following equation.

Δ ¹³ C = [concentration ratio of sample gas−concentration ratio of base gas] × 10 ³ / [concentration ratio of base gas]
(Unit: Per mill (per thousand))

[0045]

As described above, according to the present invention, dilution is carried out so as not to change the composition of the constituent gas of exhalation,
Since the CO ₂ concentration can be made substantially the same for the two types of gas to be measured, the range in which the calibration curve of ¹² CO _{2 or} the calibration curve of ¹³ CO ₂ is used can be narrowed. As the calibration curve has a narrower range, a higher accuracy can be obtained. Therefore, by limiting the range in which the calibration curve is used, measurement accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an isotope gas spectrometer.

FIG. 2 is a diagram showing a gas flow path of the isotope gas spectrometer. (a) And (c) is a figure which shows the gas flow path at the time of wash | cleaning by making a clean reference gas flow into a cell room. (b)
FIG. 3 is a diagram showing a gas flow path when a base gas is sucked from a breath bag by a gas injector 21 and then mechanically pushed out at a constant speed after sucking the base gas. (d) Inhales the sample gas from the expiration bag with the gas injector 21.
It is a figure which shows the gas flow path at the time of mechanically extruding at a constant speed after sucking in a sample gas.

FIG. 3 is a diagram showing a gas flow path of the isotope gas spectrometer. (a) And (d) is a figure which shows the gas flow path at the time of wash | cleaning by making a clean reference gas flow into a cell room. (b)
FIG. 3 is a diagram showing a gas flow path when a three-way valve V ₄ is opened to the atmosphere side and a predetermined amount of air is sucked in by the gas injector 21.
(c) is a diagram showing a gas flow path when a base gas is sucked from the expiration bag by the gas injector 21 and then mechanically pushed out at a constant speed after sucking the base gas. (e) is a diagram showing a gas flow path when a sample gas is sucked from the expiration bag by the gas injector 21, the sample gas is sucked and mixed, and mechanically extruded at a constant speed.

[Explanation of symbols]

D infrared detecting device L infrared light source device M _1, M ₂ motor V _0, V ₁ ~V ₄ valve 11 cell chamber 11a first sample cell 11b second sample cell 11c reference cell 18 O ₂ sensor 19 humidity sensor 21 gas injector 24a first wavelength filter 24b second wavelength filter 25a first detection element 25b second detection element 31 pressure relief valve 32 regulator 33 flow meter 35 needle valve 36 check valve

Continuation of the front page (56) References JP-A-8-145991 (JP, A) JP-A-61-11634 (JP, A) JP-A-63-269036 (JP, A) US Patent 5,146,294 (US, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 21/00-21/61 G01N 33/483 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. Carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO ₂
Using a calibration curve created by introducing a gas to be measured containing component gas into the cell, determining the absorbance of transmitted light having a wavelength suitable for each component gas, and measuring a gas containing a component gas having a known concentration. In the isotope gas spectrometry for measuring the concentration of each component gas, the CO ₂ concentration of one measured gas is reduced by the CO ₂ concentration of the other measured gas for two types of measured gases collected from one sample. is higher than ₂ concentration, one of the measurement gas until the CO ₂ concentration of one of the measurement gas is equal to the CO ₂ concentration of the other gas to be measured is diluted with air, the concentration ratio of the gas to be measured ¹³ CO ^_2/12 CO ₂ isotope gas spectroscopic measurement method for measuring. 2. Carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO ₂
Using a calibration curve created by introducing a gas to be measured containing component gas into the cell, determining the absorbance of transmitted light having a wavelength suitable for each component gas, and measuring a gas containing a component gas having a known concentration. In the isotope gas spectrometry for measuring the concentration of each component gas, in the preliminary measurement, (a)
The two types of measurement gas collected from one sample, and the CO ₂ concentration of the first type of the gas to be measured, the CO ₂ concentration of the second type of gas to be measured were measured, in the measurement, (b If the measured CO ₂ concentration of the first type of gas to be measured is higher than the CO ₂ concentration of the measured second type of gas to be measured, the CO ₂ concentration of the first type of gas to be measured becomes the second CO ₂ concentration. after dilution of the first kind of gas to be measured with air until it equals the concentration of CO ₂ kinds of the measurement gas by measuring the concentration ratio ¹³ CO ^_2/12 CO ₂ in the first type of gas to be measured, (c ) the second type of proportional gas spectroscopic measurement method for measuring the concentration ratio ¹³ CO ^_2/12 CO ₂ in the measurement gas. 3. Carbon dioxide¹²CO_TwoAnd carbon dioxide¹³CO_Two
The gas to be measured, which contains
Determine the absorbance of transmitted light of a wavelength suitable for the
Created by measuring gas containing component gases
Using the calibrated calibration curve to measure the concentration of each component gas
In the body gas spectrometry method, in the preliminary measurement, (a)
For two types of gas to be measured collected from one sample,
Of the first type gas to be measured_TwoConcentration and the second type
CO of measured gas_TwoMeasure each concentration, and
And (b) the CO of the measured first type gas to be measured._TwoDark
Of the second type gas to be measured whose degree is measured_TwoThan concentration
Is lower, the concentration ratio of the first type gas to be measured¹³CO_Two/
¹²CO_TwoIs measured as it is, and (c) the second type of gas to be measured
CO_TwoThe concentration of CO in the gas to be measured of the first type_TwoConcentration etc.
The second type of gas to be measured was diluted with air until
After that, the concentration ratio of the second type gas to be measured¹³CO_Two/¹²CO_Two
Isotope gas spectrometry method for measuring gas.