JPH1183739A - 13co2 determining method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance measuring accuracy, by forming a calibration curve from the relation between<12> CO2 and an absorbancy ratio with respect to standard gases different in<13> CO2 presence ratio or the relation between<13> CO2 and an absorbancy ratio or the relation between<12> CO2 and<13> CO2 . SOLUTION: A plurality of standard gases different in<13> CO2 presence ratio and known in<13> CO2 presence ratio are used, the absorbancies in the respective<12> CO2 absorbing bands thereof are measured, and<12> CO2 absorbancy is divided by<13> CO2 absorbancy to calculate an absorbance ratio. Next, from the obtained relation between<12> CO2 absorbancy and the absorbancy ratio, a calibration curve is formed with respect to respective<13> CO2 presence ratios. Subsequently, the<12> CO2 absorbancy of sample gas unknown in<13> CO2 presence ratio are measured, and the<12> CO2 absorbancy is divided by the<13> CO2 absorbancy to calculate an absorbancy ratio. The obtained<12> CO2 absorbancy is collated with the calibration curve and, from the relation between the<13> CO2 presence ratio in<12> CO2 absorbancy and the absorbancy ratio, a primary approximate straight line is determined. Next, the absorbancy ratio obtained by the measurement of an unknown sample is collated with the primary approximate straight line to determine the presence ratio of<13> CO2 to<12> CO2 in the sample gas or the presence ratio of<13> CO2 to total CO2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring ¹³ CO ₂ , and more particularly to an improvement in measurement accuracy.

[0002]

2. Description of the Related Art The abundance ratio of ¹² CO ₂ to ¹³ CO ₂ existing in the natural world is about 99: 1. ¹³ CO contained in breath
There is a possibility that various diseases can be diagnosed by accurately measuring the abundance ratio of ₂ . A specific example is the urea breath test for diagnosing Helicobacter pylori, which is considered as one of the factors of gastric ulcer. However, in such diagnosis, it is necessary to accurately measure the ¹³ CO ₂ abundance ratio (for example, 1δ% or less). So, ¹³
As a method for measuring the CO ₂ abundance ratio, a method using a calibration curve has conventionally been generally used.

[0003] Calibration curves obtained by plotting the output of ¹² CO ₂ and ¹³ CO ₂ by flowing a gas of 1% to 5% of natural CO ₂ through a sample cell are shown in FIGS. 1 (a) and 1 (b). For example, if the output value is 500 mv, ¹³ CO ₂ shown in FIG.
From the calibration curve, the concentration of ¹³ CO ₂ is found to be about 3 × 10 ^-2 %. Further, in the method shown in FIG. 1, ¹² CO ₂ and ¹³ CO ₂
Was plotted relationship concentrations and output for each, ¹²
Calibration curves are also known in which the relationship between absorbance and concentration is plotted for each of CO ₂ and ¹³ CO ₂ . As a ¹³ CO ₂ measuring device, a sample bag containing a sample gas collected from a subject is connected to the gas inlet of the main body, and the user pushes the sample bag by hand to move the sample gas into the sample cell. Flush
^One that measures ¹³ CO ₂ is known.

[0004]

[Problems to be Solved by the Invention] However, ¹² CO
If the CO _{2 to 2} and ¹³ CO ₂ are mixed is measured by infrared spectroscopy, ¹² CO and the absorption band of the absorption band and ¹³ CO ₂ of ₂ is very close, some of these absorption spectra overlap. That is, the ¹² CO ₂ absorbance in the ¹² CO ₂ absorption band is ¹³ CO 2
Affected by ¹³ CO ₂ absorbance in the absorption band of _2, also ¹³
Since CO ₂ absorbance is affected by ¹² CO ₂ absorbance,
In the case where the relationship between ¹² CO ₂ and ¹³ CO ₂ is separated and plotted like the calibration curve of the conventional configuration, it is difficult to perform quantification with high accuracy, and there is still room for improvement in terms of measurement accuracy. However, in the field of ¹³ CO ₂ measurement, there was no technology capable of solving this.

In the conventional ¹³ CO ₂ measuring apparatus, since the user pushes the sample bag by hand to flow the sample gas, the flow rate of the sample gas flowing in the sample cell may fluctuate. . If the flow rate of the sample gas flowing in the sample cell fluctuates, the measured data will vary, and the operation of the three-way stopcock will be more complicated, and the measurer will need to be always attached to the device. There were points, and it was not satisfactory from these viewpoints. The present invention has been made in view of the problems of the prior art, and an object it is possible to improve the measurement accuracy ¹³
An object of the present invention is to provide a method and apparatus for measuring CO ₂ .

[0006]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
According to the present invention¹³CO_TwoThe measuring method is the
Process, calibration curve creation process, unknown sample measurement process, approximation
A line determination step;¹³CO_TwoAn abundance ratio determining step.
And features. The known sample measurement step,¹³CO_TwoExistence
Multiple ratios with different ratios¹³CO_TwoStandard gas with known abundance
Used, each of which¹²CO_TwoAbsorbance in the absorption band¹²C
O_TwoAbsorbance,¹³CO_TwoAbsorbance in the absorption band¹³CO_TwoSucking
Measured as luminous intensity and¹²CO_TwoAbsorbance¹³CO_TwoAbsorption
Divided by degrees or¹³CO_TwoAbsorbance¹²CO_TwoAbsorbance
Divide by to find the absorbance ratio.

[0007] The calibration curve preparing step is based on the relationship between the ¹² CO ₂ absorbance and the absorbance ratio obtained in the known sample measuring step.
A calibration curve is created for each ¹³ CO ₂ abundance ratio. The unknown sample measurement step is performed for a sample gas having an unknown ¹³ CO ₂ abundance ratio.
¹² CO ₂ absorbance measured and ¹³ CO ₂ absorbance, and the ¹² CO
₂ Absorbance divided by ¹³ CO ₂ absorbance, or ¹³ CO ₂
The absorbance is divided by the ¹² CO ₂ absorbance to determine the absorbance ratio. The approximation straight line determination step compares the ¹² CO ₂ absorbance obtained in the unknown sample measurement step with the calibration curve obtained in the calibration curve creation step, and determines the ¹³ CO ₂ abundance ratio and the absorbance ratio in the ¹² CO ₂ absorbance. Is determined from the relationship.

In the step of determining the ¹³ CO ₂ abundance ratio, the absorbance ratio obtained in the unknown sample measuring step is compared with the primary approximate straight line obtained in the approximate line determining step, and the ¹² C in the sample gas is determined.
Abundance ratio of O ₂ for ¹³ CO _2, or to determine the abundance ratio of relative該全CO ₂ ¹³ CO _2. In the ¹³ CO ₂ measurement method, the calibration curve creating step creates a calibration curve for each ¹³ CO ₂ abundance ratio from the relationship between the ¹³ CO ₂ absorbance and the absorbance ratio obtained in the known sample measurement step. is intended, the approximate straight line determining step, the unknown sample measurement step ¹³ CO ₂ absorbances obtained in collated the obtained calibration curve in the calibration curve generating step, ¹³ in the ¹³ CO ₂ absorbance
It is also possible to determine a first-order approximate straight line from the relationship between the CO ₂ abundance ratio and the absorbance ratio.

In the method for measuring ¹³ CO ₂ , the step of preparing a calibration curve may be performed by the step of measuring a known sample.
^From the relationship between ¹² CO ₂ absorbance and ¹³ CO ₂ absorbance, each ¹³ C
A calibration curve is created for the O ₂ abundance ratio, and the approximation line determination step is performed in the unknown sample measurement step.
¹² CO ₂ absorbance against a calibration curve obtained by the calibration curve creating process, and ¹³ CO ₂ abundance in the ¹² CO ₂ absorbance ¹³
A first-order approximation straight line is determined from the relationship between the CO ₂ absorbances. The ¹³ CO ₂ abundance ratio determination step is based on the first-order approximation straight line obtained in the approximation straight line determination step and obtained in the unknown sample measurement step. Check the ¹³ CO ₂ absorbance and check the ¹² C
Abundance ratio of O ₂ for ¹³ CO _2, or it is possible to determine the abundance ratio of該全CO ₂ for ¹³ CO _2.

In the method for measuring ¹³ CO ₂ , the step of preparing a calibration curve may be performed by the step of measuring a known sample.
^From the relationship between ¹² CO ₂ absorbance and ¹³ CO ₂ absorbance, each ¹³ C
A calibration curve is created for the O ₂ abundance ratio, and the approximation line determination step is performed in the unknown sample measurement step.
The ¹³ CO ₂ absorbance against a calibration curve obtained by the calibration curve creating process, and ¹³ CO ₂ abundance in the ¹³ CO ₂ absorbance ¹²
A first-order approximation straight line is determined from the relationship between the CO ₂ absorbances. The ¹³ CO ₂ abundance ratio determination step is based on the first-order approximation straight line obtained in the approximation straight line determination step and obtained in the unknown sample measurement step. Check the ¹² CO ₂ absorbance and check the ¹² C
Abundance ratio of O ₂ for ¹³ CO _2, or it is possible to determine the abundance ratio of該全CO ₂ for ¹³ CO _2.

Further, according to the present invention,¹³CO_Twomeasuring device
Are known sample measurement means, calibration curve creation means, and unknown sample
Measurement preparation means, unknown sample measurement means, approximate curve determination means
Steps and¹³CO_TwoAbundance ratio determination means.
And The known sample measuring means,¹³CO_TwoExistence ratio is different
Become multiple¹³CO_TwoUsing a standard gas with a known abundance ratio,
Each of¹²CO_TwoAbsorbance in the absorption band¹²CO_TwoAbsorption
Every time,¹³CO_TwoAbsorbance in the absorption band¹³CO_TwoAbsorbance
Measurement.¹²CO_TwoAbsorbance¹³CO_TwoDivide by absorbance
Calculation, or¹³CO_TwoAbsorbance¹²CO_TwoDivide by absorbance
To determine the absorbance ratio.

[0012] The calibration curve creating means is based on the relationship between the ¹² CO ₂ absorbance and the absorbance ratio obtained by the known sample measuring means.
A calibration curve is created for each ¹³ CO ₂ abundance ratio. The unknown sample measuring means is provided for measuring a sample gas having an unknown ¹³ CO ₂ abundance ratio.
¹² CO ₂ absorbance measured and ¹³ CO ₂ absorbance, and the ¹² CO
₂ Absorbance divided by ¹³ CO ₂ absorbance, or ¹³ CO ₂
The absorbance is divided by the ¹² CO ₂ absorbance to determine the absorbance ratio. The approximate curve determining means compares the ¹² CO ₂ absorbance obtained by the unknown sample measuring means with the calibration curve obtained by the calibration curve creating means, and determines the ¹³ CO ₂ abundance ratio and the absorbance ratio in the ¹² CO ₂ absorbance. Is determined from the relationship.

The ¹³ CO ₂ abundance ratio determining means compares the absorbance ratio obtained by the unknown sample measuring means with the first-order approximate straight line obtained by the approximate straight line determining means, and determines the ¹² C in the sample gas.
Abundance ratio of O ₂ for ¹³ CO _2, or to determine the abundance ratio of relative該全CO ₂ ¹³ CO _2.

[0014] In the ¹³ CO ₂ measuring apparatus, the calibration curve creating means is obtained by the known sample measuring means.
^From the relationship between the ¹³ CO ₂ absorbance and the absorbance ratio, a calibration curve is created for each ¹³ CO ₂ abundance ratio, and the approximate straight line determining means uses the ¹³ CO 2 obtained by the unknown sample measuring means.
₂ absorbance against a calibration curve obtained by the calibration curve creating means, it is possible to determine the first-order approximation straight line from the relationship of the ¹³ CO ₂ abundance and absorbance ratio in the ¹³ CO ₂ absorbance.

In the ¹³ CO ₂ measuring apparatus, the calibration curve creating means is obtained by the known sample measuring means.
^From the relationship between ¹² CO ₂ absorbance and ¹³ CO ₂ absorbance, each ¹³ C
A calibration curve is created for the O ₂ abundance ratio, and the approximate straight line determining means is obtained by the unknown sample measuring means.
^{The 12} CO ₂ absorbance was compared with the calibration curve obtained by the above-mentioned calibration curve creating means, and the ¹³ CO ₂ abundance and the ¹³ CO ₂ abundance in the ¹² CO ₂ absorbance were compared.
A first-order approximation straight line is determined from the relationship of the CO ₂ absorbance, and the ¹³ CO ₂ abundance ratio determining means obtains the first-order approximation straight line obtained by the approximation straight line determining means by the unknown sample measuring means. Check the ¹³ CO ₂ absorbance and check the ¹² C
Abundance ratio of O ₂ for ¹³ CO _2, or it is possible to determine the abundance ratio of該全CO ₂ for ¹³ CO _2.

Further, in the ¹³ CO ₂ measuring apparatus, the calibration curve creating means is obtained by the known sample measuring means.
^From the relationship between ¹² CO ₂ absorbance and ¹³ CO ₂ absorbance, each ¹³ C
A calibration curve is created for the O ₂ abundance ratio, and the approximate straight line determining means is obtained by the unknown sample measuring means.
The ¹³ CO ₂ absorbance against a calibration curve obtained by the calibration curve creating means, and ¹³ CO ₂ abundance in the ¹³ CO ₂ absorbance ¹²
A first-order approximation straight line is determined from the relationship of the CO ₂ absorbance, and the ¹³ CO ₂ abundance ratio determining means obtains the first-order approximation straight line obtained by the approximation straight line determining means by the unknown sample measuring means. Check the ¹² CO ₂ absorbance and check the ¹² C
Abundance ratio of O ₂ for ¹³ CO _2, or it is possible to determine the abundance ratio of該全CO ₂ for ¹³ CO _2.

The term "calibration curve" used herein includes those which can be represented on two-dimensional coordinates or three-dimensional coordinates. Further, according to the present invention in order to achieve the object ¹³
The CO ₂ quantifying device is a ¹³ CO ₂ quantifying device for connecting a sample bag containing a sample gas to a gas inlet, flowing the sample gas in the sample bag to a sample cell, and measuring ¹³ CO ₂ in the sample gas. Wherein a gas injection means is provided which is capable of flowing a sample gas in a sample bag connected to the gas inlet into the sample cell at a constant flow rate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing a ¹³ CO ₂ measuring apparatus according to an embodiment of the present invention. The ¹³ CO ₂ measurement apparatus 10 shown in FIG. 1 includes a preparation unit 12, a measurement unit 14, and a CPU 16. Preparation means 12
Is a standard gas with a known ¹³ CO ₂ abundance ratio ( ¹² CO ₂ and ¹³ CO ₂
Are mixed), and a plurality of ¹³ C having different ¹³ CO ₂ abundance ratios are prepared.
A standard gas having a known O ₂ abundance ratio is obtained.

The measuring means 14 has an absorption band of ¹² CO ₂ (for example, 2390) of the standard gas obtained by the preparing means 12.
The absorbance from cm ^-1 in 2290cm ^{-1) 12} CO ₂
Absorbance was measured by infrared spectroscopy as absorbance ¹³ CO ₂ absorbance in the absorption band of ¹³ CO ₂ (e.g. 2220Cm ^-1 from 2320cm ^-1), also the ¹³ CO ₂ absorbance ¹² CO ₂
Absorbance ratio was divided by the absorbance ⁽¹³ CO ₂ absorbance / ¹² CO ₂
Absorbance). Further, this measuring means 14 is provided with ¹³ CO
₂ abundance unknown sample gas ⁽¹² CO ₂ and ¹³ CO ₂ are mixed) ^1
2 CO ₂ absorbance and ¹³ CO ₂ absorbance were measured by infrared spectroscopy,
The obtaining the ¹³ CO ₂ absorbance and absorbance ratio divided by ¹² CO ₂ absorbances ⁽¹³ CO ₂ absorbance / ¹² CO ₂ absorbance). The CPU 16 includes a calibration curve creating unit 18, an approximate straight line determining unit 20, and a ¹³ CO ₂ abundance ratio determining unit 22.

Based on the relationship between the ¹² CO ₂ absorbance and the ¹³ CO ₂ absorbance of the standard gas obtained by the measuring means 14, the calibration curve creating means 18 determines each ¹³ CO ₂ abundance (for example, −24.
6δ%, -9.51δ%, 12.62δ%, 33.1δ
Create a calibration curve for%). However, here δ%
Is a value when the abundance ratio of ¹³ CO ₂ to ¹² CO ₂ in the arrowhead stone is 0δ%.

[0021] The approximation-line determining unit 20 collates the ¹² CO ₂ absorbance of the sample gas obtained in the measuring means 14 to the calibration curve obtained in the calibration curve creating means 16, the ¹² CO ₂
A first-order approximation straight line is determined from the relationship between the ¹³ CO ₂ abundance ratio and the absorbance ratio ( ¹³ CO ₂ absorbance / ¹² CO ₂ absorbance) in the absorbance. The ¹³ CO ₂ abundance ratio determining means 22 checks the absorbance ratio ( ¹³ CO ₂ absorbance / ¹² CO ₂ absorbance) of the sample gas against the primary approximate straight line obtained by the approximate straight line determining means 20,
The ratio of ¹³ CO ₂ to ¹² CO ₂ in the sample gas is determined.

The ¹³ CO ₂ measuring apparatus 10 according to the present embodiment
Is configured as described above, and its operation will be described below. As one embodiment of the present invention, the preparation means 1
FIG. 3 specifically shows the processing contents from the preparation step by the step 2 to the calibration curve creation step by the calibration curve creation means 16. 1. First, a preparation step by the preparation means 12 is performed.

That is, the preparation means 12 comprises four 5% standard gases ( ¹³ CO ₂ abundance ratio: -24.6δ%, -9.51δ).
%, 12.62 δ%, 33.1 δ%) are diluted with, for example, N ₂ gas, and the respective ¹³ CO ₂ abundance ratios (−24.6 δ) are diluted.
%, -9.51 δ%, 12.62 δ%, 33.1 δ%)
A standard gas of 2, 3 and 4% is prepared (S1). In the present embodiment, each of the ¹³ CO ₂ abundances (−24.6δ) is used as a standard gas for preparing a calibration curve.
%, -9.51 δ%, 12.62 δ%, 33.1 δ%)
, 2, 3, 4 and 5% are used.
2. After the completion of the preparation step, a known sample measuring step by the measuring means 14 is performed.

That is, the measuring means 14 obtains −24.6δ.
Measure 3%, 4%, and 5% in order from 2% of%. After that, 3%, 4%, and 5% of -9.51 δ%, 12.62 δ%, and 33.1 δ% are similarly measured in order from 2% (S
2). 3. Then, the results of 16 points (4 × 4 points) are plotted with ¹² CO ₂ absorbance on the horizontal axis (x axis) of the graph, and the absorbance ratio ( ¹³ CO ₂ absorbance / ¹² CO ₂ ) is plotted on the vertical axis (y axis) of the graph. Absorbance) and plotting (S3). 4. After the plotting is completed, a calibration curve creation step by the calibration curve creation means 16 is performed.

That is, the calibration curve creating means 16
Regarding the ¹³ CO ₂ abundance ratio (δ%), a quadratic approximation formula 24 (y =
ax ² + bx + c) (S4). In the present embodiment, the second-order approximation formula 24a (y = 0.7389x ² -0.5644x) is used when the ¹³ CO ₂ abundance ratio is −24.6δ%.
+0.7086), ¹³ CO ₂ abundance ratio for -9.51δ% 2-order approximation formula 24b (y = 0.7389x ² -0.
5644x + 0.7131), ¹³ CO ₂ abundance ratio is 12.
The quadratic approximation 24c (y = 0.7389) for 62δ%
^{x 2 -0.5644x + 0.7198), 13} CO 2 abundance ratio for 33.1δ% 2-order approximation formula 24d (y = 0.7
389x ² -0.5644x + 0.7259) was determined. Note that the R ² value in the figure is an index indicating the degree of correlation, and is specifically obtained from the following equations (1) to (3).

(Equation 1)

(Equation 2)

(Equation 3) Then, the quadratic approximation equation 24a~24d standard gas ¹²
It is used as a calibration curve of the CO ₂ absorbance and the absorbance ratio ( ¹³ CO ₂ absorbance / ¹² CO ₂ absorbance) (see FIG. 4).

Next, as an embodiment of the present invention, specifically the view processing contents from an unknown sample measurement step to the ¹³ CO ₂ present ratio determination steps with ¹³ CO ₂ present ratio determining means 22 by the measuring means 14 4 to 5. 1. After the completion of the calibration curve creation step, an unknown sample measurement step by the measurement means 14 is performed.

That is, the measuring means 14 measures the ¹² CO ₂ absorbance and the ¹³ CO ₂ absorbance of the sample gas whose ¹³ CO ₂ abundance ratio is unknown (S 5). 2. Then, the ¹³ CO ₂ absorbance of the sample gas is divided by the ¹² CO ₂ absorbance to obtain an absorbance ratio of the sample gas (
¹³ CO ₂ absorbance / ¹² CO ₂ absorbance). 3. After the end of the unknown sample measuring step, an approximate straight line determining step by the approximate straight line determining means 20 is performed.

That is, as shown in FIG. 4, the approximate straight line determining means 20 enters the ¹² CO ₂ absorbance (for example, 0.2) of the sample gas into the quadratic approximate expressions 24a to 24d, and extends the line vertically therefrom. (S7). For example, the sample gas ¹² CO
When ₂ absorbance is 0.2, ^1, as shown in FIG. 4 ² C
Draw a line with O ₂ absorbance (x) = 0.2. 4. Vertically extended straight line (x = 0.2) and quadratic approximate expressions 24a to 24d
(S8).

For example, the ¹² CO ₂ absorbance (x) = 0.
2 (P _a ,
P _b, P _c, determine the P _d). 5. Taking each ¹³ CO ₂ abundance ratio (δ%) on the horizontal axis (x-axis) of the graph, the intersection P _a ,
P _b, P _c, the absorbance ratio at P _d ⁽¹³ CO ₂ absorbance / ¹² C
O ₂ absorbance) is plotted on the vertical axis (y axis) of the graph, and a first-order approximate straight line 26 (y = dx + e) shown in FIG. 6 is drawn (S
9).

For example, a first-order approximation straight line 26 (y = 0.00
03x + 0.6327) is subtracted. It should be noted that the R ² value in the figure is specifically obtained from the above equations 1 to 3, but in this case, since it is a first-order regression, it is the same as the square of the correlation coefficient. 6. The first-order approximation line 26 shows the absorbance ratio of the sample gas (
¹³ CO ₂ absorbance / ¹² CO ₂ absorbance) are collated to determine the ¹³ CO ₂ abundance ratio (δ%) (S10). For example, if the absorbance ratio of the sample gas ( ¹³ CO ₂ absorbance / ¹² CO ₂ absorbance) is 0.6
3, the abundance ratio (δ%) of ¹³ CO ₂ to ¹² CO ₂ in the sample gas is − from the first-order approximation line 26 shown in FIG.
0.83δ% is obtained.

As described above, according to the ¹³ CO ₂ measuring apparatus 10 according to the present embodiment, the ¹² CO ₂ absorbance of the standard gas is plotted on the horizontal axis (x axis) of the graph, and the vertical axis (y axis) is plotted on the graph. Similarly, since the absorbance ratio of the standard gas was determined ( ¹³ CO ₂ absorbance / ¹² CO ₂ absorbance), the ¹² CO ₂ absorbance of the standard gas was correlated with the ¹³ CO ₂ absorbance, and the second approximation formula 24a shown in FIG. ~ 24d (calibration curve) can be obtained.

The sample gas whose ¹³ CO ₂ abundance ratio is unknown
^{The 12} CO ₂ absorbance is compared with the second approximation formulas 24a to 24d,
¹³ CO ₂ abundance in ¹² CO ₂ absorbance of the sample gas and the absorbance ratio ⁽¹³ CO ₂ absorbance / ¹² CO ₂ absorbance) a primary approximate line 26 from the relationship between the determined, the sample gas to the first order approximation straight line 26 against the absorbance ratio ⁽¹³ CO ₂ absorbance / ¹² CO ₂ absorbance), so it was decided to determine the ¹³ CO ₂ abundance, ¹²
Correlating the CO ₂ absorbance and ¹³ CO ₂ absorbance can be obtained ¹³ CO ₂ present ratios.

As a result, the absorption band of ¹² CO _{2 and} the absorption band of ¹³ CO ₂ are very close to each other, and a part of these absorption spectra overlap, so that ¹² C ₂ in the sample gas in which ¹² CO ₂ and ¹³ CO ₂ are mixed exists.
Only the ¹³ CO ₂ abundance ratio to O ₂ can be accurately measured. It should be noted that the ¹³ CO ₂ measuring apparatus of the present invention is not limited to the above configuration, and various modifications can be made within the scope of the invention.

Modification 1 For example, in the ¹³ CO ₂ measuring apparatus 10, the second approximation formulas 24 a to 24 d (calibration curves) are obtained from the relationship between the ¹² CO ₂ absorbance and the absorbance ratio ( ¹³ CO ₂ absorbance / ¹² CO ₂ absorbance). As described above, the case where ¹³ CO ₂ absorbance and absorbance ratio ( ¹³ C
It is also possible to create a calibration curve from the relationship of (O ₂ absorbance / ¹² CO ₂ absorbance).

Modification 2 In each of the above-described configurations, the absorbance of ¹² CO ₂ and the absorbance ratio ( ¹³
The relationship of the CO ₂ absorbance / ¹² CO ₂ absorbance), but the second-order approximation equation 24, as shown in FIG. 4 has been described a case where obtained in the two-dimensional coordinate system consisting of x-axis and y-axis, further z graphs On the axis, the ratio of ¹³ CO ₂ in the standard gas
4.6δ%, -9.51δ%, 12.62δ%, 33.
By plotting 1δ%, it is also possible to display the relationship between the ¹² CO ₂ absorbance and the absorbance ratio on, for example, the three-dimensional coordinates of the display means 17 (for example, a display) shown in FIG. 2 (see FIG. 7A). ). Thus, it is possible to obtain a calibration curve 124 that is visually superior to that obtained by displaying the calibration curve 24 on the display means 17 on two-dimensional coordinates.

[0036] Modification 3 Further, the ¹³ CO ₂ measuring apparatus 10 shown in FIG. 2, can be the calibration curve creating means 18 creates a ^{1 2} CO ₂ absorbance and ¹³ CO ₂ calibration curves 224 from relationship absorbance (See FIG. 7B). According to the ¹³ CO ₂ measuring apparatus according to the third modification, the horizontal axis (x-axis) of the graph indicates that the sample gas ¹²
Since the CO ₂ absorbance was taken and the ¹³ CO ₂ absorbance of the sample gas was taken on the vertical axis (y-axis) of the graph, the ¹² CO ₂ absorbance and the ¹³ CO ₂ absorbance were correlated as in the first embodiment. Thus, a quadratic approximation formula 224 (calibration curve) can be obtained.

Then, the ¹² CO ₂ absorbance of the sample gas and the ¹³ C
The O ₂ absorbance was measured, and the ¹² CO ₂ absorbance of the sample gas was compared with the calibration curve 224 to obtain ¹³ C in the ¹² CO ₂ absorbance.
O ₂ abundance and ¹³ CO ₂ absorbance determined primary approximate line from the relation, to the first order approximation straight line against the ¹³ CO ₂ absorbance of the sample gas, so it was decided to determine the ¹³ CO ₂ abundance, the As in each configuration, the ¹³ CO ₂ abundance to the ¹² CO ₂ in the sample gas can be determined by correlating the ¹² CO ₂ absorbance with the ¹³ CO ₂ absorbance. Thus, the absorption band of ¹² CO ₂ and ¹³ CO ₂
¹² of the absorption band is very close, some of these absorption spectra overlap, the sample ^{gas 12} CO ₂ and ¹³ CO ₂ are mixed
¹³ CO ₂ present ratio CO ₂ only can be accurately measured.

Modification Example 4 In the above-described configuration, the absorbance of ¹² CO _{2 of the} standard gas and ¹³ C
Referring to the ¹² CO ₂ absorbance of the sample gas in the second approximation equation 224 of the O ₂ absorbance, the ¹³ CO ₂ abundance ratio in the ¹² CO ₂ absorbance is calculated.
¹³ has been described as being determined primary approximate line from CO ₂ absorbance relationship, ¹² CO ₂ absorbance and ¹³ C of the standard gas
The ¹³ CO ₂ absorbance of the sample gas is referred to the second approximation formula 224 of the O ₂ absorbance, and the ¹³ CO ₂ abundance at the ¹³ CO ₂ absorbance is calculated.
It is also possible to determine a first-order approximate straight line from the relationship between the ¹² CO ₂ absorbance.

Modification 5 In Modification 4, the case where the quadratic approximation equation 224 is obtained on the two-dimensional coordinates of the x-axis and the y-axis as shown in FIG. 7B has been described. Further, the ¹³ CO ₂ abundance ratio of the standard gas is plotted on the z-axis of the graph, for example, −24.6δ.
%, −9.51 δ%, 12.62 δ%, and 33.1 δ%, and plots the relationship between the ¹² CO ₂ absorbance and the ¹³ CO ₂ absorbance, for example, the display means 17 (for example, a display) shown in FIG.
Can be displayed on the three-dimensional coordinates (see FIG. 7).
(C)). Thereby, the calibration curve 22 is displayed on the display means 17.
It is also possible to obtain a visually superior calibration curve 324 by comparing 4 with that displayed on two-dimensional coordinates.

[0040] In this addition, the respective components has been described for the case where a ¹³ CO ₂ abundance as absorbance ratio was used divided by ¹² CO ₂ absorbance, of course, the ¹² CO ₂ abundances
It is also possible to use a value obtained by dividing by ¹³ CO ₂ absorbance. Further, in the respective configurations, for ¹² CO ₂ ¹³ CO ₂
¹³ C vs. ¹² CO _{2 in} arrowhead stone as abundance ratio (δ%)
Although the case where the value of the O ₂ abundance ratio is used as a reference has been described, other arbitrary values may be used.

Further, in the respective configurations, ¹³ CO ₂ has described the case where the abundance ratio with abundance of ¹² CO ₂ for ¹³ CO ₂ in the sample gas, the total CO ₂ for ¹³ CO ₂
May be used. In each of the above configurations, the CP
The secondary approximation formula (calibration curve) obtained by U16 and the primary approximation straight line may be further displayed on the display means 17, but of course,
Without displaying the obtained value on the display means 17, each parameter (a,
b, c) It is only necessary to determine each parameter (d, e) of the first-order approximate straight line (y = dx + e).

Further, in each of the above-described configurations, the case where the measurement data measured by the general measurement means 14 is used has been described. In the present embodiment, the measurement is performed by the measurement means 428 having the gas injection means shown in FIG. The measurement accuracy can be further improved by performing the various ¹³ CO ₂ measurement methods using the measured data obtained.

Gas Injecting Means FIG. 8 shows a schematic configuration of the measuring means 428 provided with the gas injecting means. The measuring means 428 shown in FIG.
Sample gas inlets 430a and 430b, a syringe 432 serving as a gas injection unit, and a sample cell 434 are provided. The syringe 432 allows the sample gas in the sample bag 436 connected to the sample gas inlet 430 to flow through the sample cell 434 at a constant flow rate. The sample bag 436 contains a sample gas such as exhaled gas collected from a subject.

The measuring means 428 according to this embodiment is configured as described above, and its operation will be described below. First, the measurer connects the mouth of the sample bag 436 in which a sample gas such as exhaled gas collected from the subject is put to the sample gas inlet 430 of the main body. After connection, the measurer is the CP
When the solenoid valve 438a is opened by U416 and the syringe 432 is driven up and down in the figure, the sample bag 4
The sample gas in 36 is a sample gas inlet 430, a solenoid valve 4
The liquid is once sucked into the syringe 432 through the pipe 38 and the pipe 440. Then, the sample gas sucked into the syringe 432 is discharged at a constant flow rate and introduced into the sample cell 434.

As a result, the measurement can be performed by flowing the sample gas into the sample cell 434 at a constant flow rate, so that the variation in the measurement data due to the fluctuation in the flow rate of the sample gas flowing in the sample cell 434 can be greatly reduced. Can be. In addition, the conventional complicated operation of the three-way cock is not required, and the measurer can perform the measurement without attending the apparatus, so that the operability can be improved. In this embodiment, it is preferable to provide a flow meter 450 capable of outputting the flow rate information of the nitrogen gas from the nitrogen gas cylinder 444 as shown in FIG.

That is, at the time of the measuring step, the CP
U416 opens solenoid valve 446, closes solenoid valve 448,
By opening the electromagnetic valve 452 and adjusting the opening degree of the electromagnetic valve 446 so that the flow meter 450 outputs predetermined flow information, the flow information of the nitrogen gas introduced into the sample cell 434 can be accurately obtained. This is because the dilution ratio of the nitrogen gas to the sample gas can be accurately grasped. Further, in the present embodiment, after the measurement is completed, by flowing only the nitrogen gas in the nitrogen gas cylinder 444, the inside of the sample cell 434 can be cleaned with the nitrogen gas.

Therefore, after measuring the sample gas in the sample bag 436a and cleaning the sample cell 434, the measurer can check the CP.
The solenoid valve 438b is opened by U416, and the syringe 432 is driven up and down in the figure to measure the sample gas in the sample bag 436b, and then measure the sample gas in the sample bag 436b. Continuous measurement of the sample bag is also possible. The syringe 43
2. Each operation of the solenoid valves 438, 446, 448, and 452 is controlled by the CPU 416 as control means.

[0048]

As described above, ¹³ C according to the present invention is used.
According to the method for measuring O _2, the relationship between ¹² CO ₂ and the absorbance ratio for each standard gas having ¹³ CO ₂ abundance ratio, or the relationship between ¹³ CO ₂ and the absorbance ratio, or the relationship between ¹² CO ₂ and ¹³ CO ₂ Since the calibration curve is prepared, a calibration curve can be obtained by correlating the ¹² CO ₂ absorbance of the standard gas with the ¹³ CO ₂ absorbance. Thus, the ¹³ CO ₂ abundance can be determined by correlating the ¹² CO ₂ absorbance with the ¹³ CO ₂ absorbance. Thus, ¹² CO absorption band of the absorption band and ¹³ CO ₂ of ₂ is very close, overlap some of these absorption spectra, and ¹² CO ₂
^{13 12} CO ₂ for ¹³ CO in the sample gas to CO ₂ are mixed
The abundance ratio of ₂ or only the abundance ratio of ¹³ CO ₂ to all ¹² CO ₂ can be accurately measured. Further, according to the ¹³ CO ₂ measuring device according to the present invention, the relationship between the standard gas ¹² CO ₂ and the absorbance ratio, or the relationship between ¹³ CO ₂ and the absorbance ratio, or
^Since a calibration curve creating means for creating a calibration curve based on the relationship between ¹² CO ₂ and ¹³ CO ₂ is provided, a calibration curve can be obtained by correlating the ¹² CO ₂ absorbance of the standard gas with the ¹³ CO ₂ absorbance. Thus, the ¹³ CO ₂ abundance can be determined by correlating the ¹² CO ₂ absorbance with the ¹³ CO ₂ absorbance. Thus, ¹² CO absorption band of the absorption band and ¹³ CO ₂ of ₂ is very close, overlap some of these absorption spectra, ¹² CO ₂
When ^{13 13} for ¹² CO ₂ in the sample gas to CO ₂ are mixed C
Only the abundance ratio of O ₂ or the abundance ratio of ¹³ CO ₂ to all ¹² CO ₂ can be measured with high accuracy. Further, according to the ¹³ CO ₂ measuring apparatus according to the present invention, it is provided with gas injection means capable of flowing the sample gas in the sample bag connected to the gas inlet of the main body at a constant flow rate to the sample cell. Therefore, the flow rate of the sample gas flowing in the sample cell can be made constant. Thus, it is possible to greatly reduce the variation of the measurement data due to the fluctuation of the flow rate of the sample gas flowing in the sample cell.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a conventional calibration curve.

FIG. 2 is a diagram illustrating a ¹³ CO 2 according to a first embodiment of the present invention.
FIG. 3 is a block diagram showing a _two- measuring device.

FIG. 3 is a flowchart showing processing contents from a preparation step of the apparatus shown in FIG. 2 to a calibration curve creation step.

FIG. 4 is an explanatory diagram of a calibration curve obtained by a calibration curve creating means of the apparatus shown in FIG. 2;

FIG. 5 is a flowchart showing processing contents from an unknown sample measuring step to a ¹³ CO ₂ abundance ratio determining step by the apparatus shown in FIG. 2;

FIG. 6 is an explanatory diagram of a primary approximate straight line obtained in an approximate straight line determining step of the apparatus shown in FIG. 2;

FIGS. 7A, 7B, and 7C are explanatory views of a modified example of the calibration curve creation step according to the first embodiment of the present invention.

FIG. 8 shows ¹³ CO _{2 according} to an embodiment of the present invention.
It is explanatory drawing of the measuring means provided with the gas injection means of the measuring device.

[Explanation of symbols]

10 ... ¹³ CO ₂ measuring device 12 ... preparation means 14 ... known sample measurement means 16,416 ... CPU 18 ... calibration curve creating means 20 ... approximate line determining unit 22 ... ¹³ CO ₂ present ratio determining means 24,124,224,324 … Second-order approximation (calibration curve) 26… first-order approximation straight line 428… measuring means 430a, 430b… gas inlet 432… syringe (gas injection means) 434… sample cell 436a, 436b… sample back

Claims (9)

[Claims] A method according to claim 1] ¹² CO ₂ and ¹³ how CO ₂ measures the abundance ratio of abundance, or total CO ₂ for ¹³ CO ₂ of ^{1 3} CO ₂ for ¹² CO ₂ in the sample gas to be mixed, with ¹³ CO ₂ abundance ratio plurality of different ¹³ CO ₂ abundance known standard gas, the absorbance at ¹² CO ₂ absorption band of each ¹² CO ₂ absorbance, the absorbance at ¹³ CO ₂ absorption band ¹³
Measured as CO ₂ absorbance, and the ¹² CO ₂ absorbance was measured as ¹³ C
Divide by the O ₂ absorbance, or divide the ¹³ CO ₂ absorbance by ¹² CO
And a known sample measurement step of determining the absorbance ratio divided by ₂ absorbance, the known from the sample measuring step relationship obtained ¹² CO ₂ absorbance and absorbance ratio, the calibration of a calibration curve for ¹³ CO ₂ abundance of each Line preparation process, ¹² CO ₂ absorbance of ¹³ CO ₂ abundance unknown sample gas and ¹³ CO
₍₂₎ measuring the absorbance, dividing the ¹² CO ₂ absorbance by ¹³ CO ₂ absorbance, or dividing the ¹³ CO ₂ absorbance by ¹² CO ₂ absorbance to obtain an absorbance ratio, and an unknown sample measuring step; against the calibration curve obtained with ¹² CO ₂ absorbances obtained in the above calibration curve creation step, the ¹² CO ₂
From the relationship between the ¹³ CO ₂ abundance ratio and the absorbance ratio in the absorbance, 1
An approximate straight line determination step of determining the following approximate line, the matches approximate-line determining the primary approximate line obtained in step unknown sample measured resulting absorbance ratio in the step for ¹² CO ₂ in the sample gas ¹³ CO ₂ abundance, or the total CO
¹³ CO ₂ measuring method characterized by comprising the ¹³ CO ₂ present ratio determining step of determining the abundance ratio of ¹³ CO ₂ for _2, a. 2. A ¹³ CO ₂ measuring method according to claim 1, wherein the calibration curve generating step, the known sample measured from the relationship of the resulting ¹³ CO ₂ absorbance and absorbance ratio in the process, each of the ¹³ CO ₂
Is intended to create a calibration curve for the presence ratio, the approximate line determination step collates the ¹³ CO ₂ absorbances obtained in the unknown sample measuring step the obtained calibration curve in the calibration curve generating step, the ^{13 13. A} method for measuring ¹³ CO _2, wherein a first-order approximation straight line is determined from the relationship between the ¹² CO ₂ abundance ratio and the absorbance ratio in the CO ₂ absorbance. 3. The method according to claim 1,¹³CO_TwoMeasurement method smell
hand,  The calibration curve creation step is obtained in the known sample measurement step.
Was¹²CO_TwoAbsorbance and¹³CO_TwoFrom the relationship of absorbance,¹³
CO_TwoA calibration curve is created for the abundance ratio.
Was¹²CO_TwoThe absorbance was measured using the calibration curve
To the quantity curve¹²CO_TwoIn absorbance¹³CO_TwoAbundance ratio
When¹³CO_TwoA first-order approximation straight line is determined from the relationship between absorbance.
And said¹³CO_TwoThe abundance ratio determining step is an approximate straight line determining step.
To the linear approximation line obtained in
Was¹³CO_TwoCheck the absorbance, and¹²CO_TwoTo
Do¹³CO_TwoOr the total CO_TwoAgainst¹³CO
_TwoIs characterized by determining the abundance ratio of¹³C
O_TwoMeasuring method. 4. The method according to claim 1,¹³CO_TwoMeasurement method smell
hand,  The calibration curve creation step is obtained in the known sample measurement step.
Was¹²CO_TwoAbsorbance and¹³CO_TwoFrom the relationship of absorbance,¹³
CO_TwoA calibration curve is created for the abundance ratio.
Was¹³CO_TwoThe absorbance was measured using the calibration curve
To the quantity curve¹³CO_TwoIn absorbance¹³CO_TwoAbundance ratio
When¹²CO_TwoA first-order approximation straight line is determined from the relationship between absorbance.
And said¹³CO_TwoThe abundance ratio determining step is an approximate straight line determining step.
To the linear approximation line obtained in
Was¹²CO_TwoCheck the absorbance, and¹²CO_TwoTo
Do¹³CO_TwoOr the total CO_TwoAgainst¹³CO
_TwoIs characterized by determining the abundance ratio of¹³C
O_TwoMeasuring method. 5. ¹² abundance ratio of CO ₂ and ¹³ CO ₂ is ^{1 3} CO ₂ for ¹² CO ₂ in the sample gas to be mixed, or an apparatus for measuring the abundance ratio of to total CO ₂ ¹³ CO _2, with ¹³ CO ₂ abundance ratio plurality of different ¹³ CO ₂ abundance known standard gas, the absorbance at ¹² CO ₂ absorption band of each ¹² CO ₂ absorbance, the absorbance at ¹³ CO ₂ absorption band ¹³
Measured as CO ₂ absorbance, and the ¹² CO ₂ absorbance was measured as ¹³ C
Divide by the O ₂ absorbance, or divide the ¹³ CO ₂ absorbance by ¹² CO
_A known sample measuring means for obtaining an absorbance ratio by dividing by ₂ absorbance, and a calibration curve for each ¹³ CO ₂ abundance ratio from the relationship between the ¹² CO ₂ absorbance and the absorbance ratio obtained by the known sample measuring means. a line forming means, the ¹³ CO ₂ abundance unknown sample gas ¹² CO ₂ absorbance and ¹³ CO
₍₂₎ measuring the absorbance and dividing the ¹² CO ₂ absorbance by the ¹³ CO ₂ absorbance, or dividing the ¹³ CO ₂ absorbance by the ¹² CO ₂ absorbance to obtain an absorbance ratio; against the calibration curve obtained with ¹² CO ₂ absorbances obtained in the above calibration curve creating means, the ¹² CO ₂
From the relationship between the ¹³ CO ₂ abundance ratio and the absorbance ratio in the absorbance, 1
An approximate straight line determining means for determining a next approximate straight line; and comparing the absorbance ratio obtained by the unknown sample measuring means with the primary approximate straight line obtained by the approximate straight line determining means, to obtain a ratio of ¹³ CO ₂ to ¹² CO ₂ in the sample gas. CO ₂ abundance, or the total CO
¹³ CO ₂ measuring apparatus comprising: the ¹³ CO ₂ present ratio determining means for determining the abundance ratio of ¹³ CO ₂ for _2, a. 6. The ¹³ CO ₂ measuring apparatus according to claim 5, wherein the calibration curve creating means determines each ¹³ CO _{2 based on} the relationship between the ¹³ CO ₂ absorbance and the absorbance ratio obtained by the known sample measuring means.
Is intended to create a calibration curve for the presence ratio, the approximate-line determining means collates the ¹³ CO ₂ absorbances obtained in the unknown sample measuring section on a calibration curve obtained by the calibration curve creating means, the ^{13 13.} A ¹³ CO ₂ measuring apparatus for determining a first-order approximation straight line from the relationship between the ¹² CO ₂ abundance ratio and the absorbance ratio in the CO ₂ absorbance. 7. The method according to claim 5,¹³CO_TwoMeasurement device smell
hand,  The calibration curve creating means is obtained by the known sample measuring means.
Was¹²CO_TwoAbsorbance and¹³CO_TwoFrom the relationship of absorbance,¹³
CO_TwoA calibration curve is created for the abundance ratio.
Was¹²CO_TwoThe absorbance was measured using the calibration curve
To the quantity curve¹²CO_TwoIn absorbance¹³CO_TwoAbundance ratio
When¹³CO_TwoA first-order approximation straight line is determined from the relationship between absorbance.
And said¹³CO_TwoThe existence ratio determining means,
To the first-order approximation straight line obtained by
Was¹³CO_TwoCheck the absorbance, and¹²CO_TwoTo
Do¹³CO_TwoOr the total CO_TwoAgainst¹³CO
_TwoIs characterized by determining the abundance ratio of¹³C
O_Twomeasuring device. 8. The method according to claim 5,¹³CO_TwoMeasurement device smell
hand,  The calibration curve creating means is obtained by the known sample measuring means.
Was¹²CO_TwoAbsorbance and¹³CO_TwoFrom the relationship of absorbance,¹³
CO_TwoA calibration curve is created for the abundance ratio.
Was¹³CO_TwoThe absorbance was measured using the calibration curve
To the quantity curve¹³CO_TwoIn absorbance¹³CO_TwoAbundance ratio
When¹²CO_TwoA first-order approximation straight line is determined from the relationship between absorbance.
And said¹³CO_TwoThe existence ratio determining means,
To the first-order approximation straight line obtained by
Was¹²CO_TwoCheck the absorbance, and¹²CO_TwoTo
Do¹³CO_TwoOr the total CO_TwoAgainst¹³CO
_TwoIs characterized by determining the abundance ratio of¹³C
O_Twomeasuring device. 9. A ¹³ CO ₂ measuring apparatus in which a sample bag containing a sample gas is connected to a gas inlet, and the sample gas in the sample bag flows through a sample cell to measure ¹³ CO ₂ in the sample gas. ^13. A ¹³ CO ₂ measuring apparatus comprising gas injection means capable of flowing a sample gas in a sample bag connected to the gas inlet into the sample cell at a constant flow rate.