JP3176302B2 - Isotope gas spectrometry method and measuring device - 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 .

[0002] The present invention relates to an isotope gas spectrometry method and apparatus for measuring the concentration or concentration ratio of an isotope gas by focusing on the light absorption characteristics of the isotope.

[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]

However, even if an attempt is made to obtain the concentration ratio by using the method described in the above-mentioned publication, there are the following problems. To find the ¹² CO ₂ concentrations and the ¹³ CO ₂ concentration, a gas of known ¹² CO ₂ concentration, using a gas of known ¹³ CO ₂ concentration shall prepare a calibration curve, respectively.

[0008]¹²CO_TwoTo create a concentration calibration curve,¹²
CO_TwoTry changing the concentration several times, ¹²CO_TwoThe absorbance of
Measure and set the horizontal axis¹²CO_TwoFor concentration, the vertical axis is¹²CO_TwoSucking
Plot the magnitude and determine the curve using least squares.
It is usual to specify.¹³CO_TwoConcentration calibration curve creation
Perform in a similar manner. However, infrared spectroscopy¹³CO_Twoconcentration
Or¹³CO_TwoConcentration ratio (¹³CO_Twoconcentration/¹²CO_TwoConcentration saw
I say. The same applies hereinafter) when measuring
Exhaled breath is exhaled from the body by metabolism,
Contains water vapor at a concentration close to the state.

[0009] Infrared spectroscopy is used to measure the absorbance by using the fact that the measurement gas absorbs infrared of a specific wavelength. FIG. 5 is a graph in which a gas to be measured in which the humidity is variously changed from 0% to 100% is made, and a state in which the ¹³ CO ₂ concentration ratio changes with respect to the humidity using a gas having a humidity of 0% as a base gas. is there.

From this graph, it can be seen that the ¹³ CO ₂ concentration ratio is not constant but changes according to humidity. Therefore, without knowing this fact, if the ¹³ CO ₂ concentration or the ¹³ CO ₂ concentration ratio is measured with respect to the gas to be measured containing water, it is apparent that a result larger than the actual one appears.

As a solution to this problem, there is a method in which the moisture of the breath to be measured is removed beforehand with a moisture adsorbent such as molecular sieves or magnesium perchlorate. There is a problem that a large space for placing the water adsorbent is required, there is no means for confirming whether the water removal by the water adsorbent is reliable, and the water adsorbent needs to be periodically replaced.

In view of the above, the present invention solves the above-mentioned technical problems, and introduces a gas to be measured containing carbon dioxide ¹³ CO ₂ as a component gas into a cell to perform a spectroscopic measurement. It is an object of the present invention to realize an isotope gas spectroscopic measurement method and a measurement apparatus capable of accurately measuring and correcting the concentration or concentration ratio of a component gas by measuring the gas concentration.

[0013]

According to the isotope gas spectrometry of the present invention, a gas to be measured, which is human breath, is introduced into a cell,
The first step of determining the absorbance corresponding to the wavelength of about 4412 nm of the component gas ¹³ CO ₂ , using a calibration curve created by measuring a gas containing a known concentration of the component gas,
The second step for determining the concentration of the component gas, and measuring the concentration of water vapor contained in the gas to be measured, using a correction line created by measuring a gas having a known concentration of water vapor,
The method includes a third step of correcting the concentration of the component gas according to the measured water vapor concentration (claim 1).

Further, according to the isotope gas spectrometry method of the present invention, the plurality of component gases are carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO ₂ , the gas to be measured is introduced into a cell, and the wavelength of each component gas , About 4280n for carbon ¹² CO ₂
m, the first step of determining the absorbance corresponding to about 4412 nm for carbon dioxide ¹³ CO ₂ , using a calibration curve created by measuring a gas containing a component gas of a known concentration, A second step of determining the concentration ratio, and measuring the water vapor concentration contained in the gas to be measured,
The method includes a third step of correcting the concentration or concentration ratio of the component gas according to the measured water vapor concentration using a correction line by measuring a gas having a known water vapor concentration (claims 2 and 6 ).

According to the method described above, as compared with conventional methods, in the third step, the water vapor concentration using the correction curve prepared was measured by the water vapor concentration measuring a known gas A method of correcting the concentration or the concentration ratio of the component gas according to the above is added. By this correction, the concentration of the component gas should be a constant value, but taking into account the phenomenon that the measured concentration of the component gas fluctuates according to the difference in the water vapor concentration, the measurement accuracy of the component gas concentration or concentration ratio is considered. Can be enhanced.

The water vapor concentration may be detected by using various humidity sensors, or may be calculated by obtaining the absorbance in a water molecule spectrum by a spectroscopic method. The correction line in the third step in the method according to claim 2 or 6 , specifically, for a plurality of gases having different water vapor concentrations, determine the absorbance corresponding to the wavelength of each component gas, and use the calibration curve. To determine the concentration or concentration ratio of each component gas,
The ratio or difference of the determined concentration or concentration ratio of each component gas is obtained by plotting against the water vapor concentration, and the correction method in the third step is obtained in the third step for the gas to be measured. The concentration of water vapor is applied to the correction line to obtain a concentration correction value or a concentration ratio correction value for the component gas, and the concentration or concentration ratio of the component gas obtained in the second step is calculated as the concentration correction value obtained from the correction line. Alternatively, it is performed by dividing or subtracting by the concentration ratio correction value (claims 3 and 7 ).

Further, the isotope gas spectrometer of the present invention is a measuring apparatus for performing the above-mentioned isotope gas spectrometry method of the present invention, and is provided to a cell as a means for realizing a data processing function. Was measured for the gas to be measured,
About 4280 nm for carbon dioxide ¹² CO ₂ ,
About carbon ¹³ CO ₂ , light having a wavelength of about 4412 nm is transmitted.
A first and a second wavelength filters to be passed, an absorbance calculating means for obtaining an absorbance based on an amount of light corresponding to a wavelength suitable for each component gas, and measuring a gas containing a component gas having a known concentration. Using the detection line created by
Using a concentration calculating means for calculating the concentration or concentration ratio of the component gas, a water vapor concentration measuring means for measuring the water vapor concentration contained in the gas to be measured, and a correction line created by measuring a gas having a known water vapor concentration. is intended to include a correction means for correcting the concentration or concentration ratio of component gases in response to the measured water vapor concentration was (claims 4, 8).

[0018]

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”.

The 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;
Of 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 CO ₂ concentration of the base gas measured in advance is measured, the C ₂ concentration of the sample gas measured in advance 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.

[0030] 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 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. 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 from the absorbance using a calibration curve. III-3. Reference Measurement Next, the reference gas is flowed by 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 the reference gas until the O ₂ concentration becomes equal to the CO ₂ concentration of the sample gas,
Measure the light quantity of the base gas.

Specifically, as shown in FIG. 3B, the valve V ₁ is opened, and a predetermined amount of the reference gas is sucked by the gas injector 21. Next, as shown in FIG.
₃ is opened, the base gas is sucked by the gas injector 21 and mixed with the reference gas. Since it is diluted like this,
Since the CO ₂ concentration can be made substantially the same for the two types of expiration, the range in which the calibration curve for ¹² CO _{2 and} the calibration curve for ¹³ CO ₂ can be used can be narrowed.

[0035] 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.

The amount of light ¹² R ₂ obtained by the first detection element 25 a and the amount of light ¹³ R ₂ obtained by the second detection element 25 _b are written as described above. 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.

[0037] 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 the reference gas, the light intensity of the sample gas is measured by the respective detection elements 25a and 25b. In this way,
The amount of light obtained by the first detection element 25a ¹² S, write the resulting quantity and the ¹³ S in the second detection element 25b. 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.

Thus, the light amount ¹² R ₃ obtained by the first detection element 25 a and the light amount ¹³ R ₃ obtained by the second detection element 25 b are written. 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).

[0039] 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).

[0041] 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 calculated, and the absorbance is calculated using the average value and the light amounts 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.

The calibration curve is prepared 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 prepare a calibration curve, change the ¹² CO ₂ concentration in the range of about 0% to 6%, and measure the absorbance of ¹² 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 ¹³ CO ₂ concentration is adjusted to 0.00% to 0.0%.
The absorbance of ¹³ CO ₂ is measured while changing it in the range of about 7%. 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, a gas containing ¹² CO ₂ and a gas containing ¹³ CO ₂ are measured independently, and a 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 is¹³Conc (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 Sample gas and base gas were compared¹³The 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)) IV-6. Correction of Change in ¹³ C Then, the water vapor concentration correction (humidity correction) according to the present invention is performed on the change Δ ¹³ C in the ¹³ CO ₂ concentration ratio of the base gas and the samble gas.

Therefore, the output of the humidity sensor 19
The measure of variation delta ¹³ C of ¹³ CO ₂ concentration ratio with a graph plotting, for correcting the variation delta ¹³ C of ¹³ CO ₂ concentration ratio. The method of creating this graph is specifically as follows. A 3% CO ₂ / N ₂ balance gas with a humidity of 0% is placed in two gas bags, and steam is injected into one of the gas bags until the gas is saturated, and the humidity is adjusted to 100%. These two gases are mixed to produce a sample gas in which the humidity is changed in five steps from 0% to 100%, and one type of base gas having the same humidity of 0% is produced.
An output value corresponding to the humidity of the base gas detected by the humidity sensor 19 is obtained, an output value corresponding to the humidity of the sample gas is obtained, and the difference ΔV between the output values is plotted on the horizontal axis. Since the humidity of the base gas is 0%, the difference ΔV in the output value is a value corresponding to the humidity itself of the sample gas. And
The difference between the ¹³ CO ₂ concentration ratio and the base ¹³ CO ₂ concentration ratio of the gas of the sample gas obtained using the calibration curve taken longitudinal axis to create a chart.

Table 1 shows examples of numerical values actually obtained.

[0051]

[Table 1]

In Table 1, the sensor output value of the base gas should be constant, but the measured value is not constant but drifts. This is because there was a problem with the response speed of the humidity sensor 19, and the measurement was performed before the humidity sensor 19 was in a completely equilibrium state. FIG. 4 is a graph of the numerical values in Table 1. Using this graph and the difference between the output values of the humidity sensor 19 between the base gas and the sample gas, the change Δ ¹³ C in the ¹³ CO ₂ concentration ratio between the base gas and the sample gas is calculated as:
Can be corrected.

[0053]

As described above, according to the isotope gas spectroscopic measurement method or measuring apparatus of the present invention, when exhaled gas containing carbon dioxide ¹³ CO ₂ as a component gas is introduced into a cell and spectroscopically measured, the exhaled gas is included in the exhaled gas . Since the correction based on the water vapor concentration is performed, the concentration or concentration ratio of the component gas can be measured with better accuracy.

[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. 4 is a diagram showing a gas flow path when a predetermined amount of a reference gas is sucked 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 and mixed by the gas injector 21 from the expiration bag and mechanically extruded at a constant speed.

[4] ¹³ CO ₂ concentration ratio is prepared constant CO _2, by mixing a CO ₂ containing CO ₂ and moisture does not contain the moisture, make many varied sample gas humidity, similarly humidity One kind of base gas of 0% is made and the humidity sensor 19
The difference ΔV between the output value corresponding to the humidity of the base gas and the output value corresponding to the humidity of the sample gas detected on the horizontal axis is plotted, and the ¹³ CO _{2 of the} sample gas obtained using the calibration curve is plotted on the horizontal axis.
It is a graph created with the vertical axis representing the difference between the concentration ratio and the ¹³ CO ₂ concentration ratio of the base gas.

FIG. 5 shows sample gases with various humidity values.
4 is a graph showing a relationship between humidity and a ¹³ CO ₂ concentration ratio. ¹³
The CO ₂ concentration ratio is standardized by the smallest value of the ¹³ CO ₂ concentration ratio.

[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

────────────────────────────────────────────────── (5) References JP-A-5-296922 (JP, A) JP-A-62-261032 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/00-21/61 G01N 33/497 JICST file (JOIS) WPI / L

Claims (9)

(57) [Claims] 1. A gas to be measured including a component gas is introduced into a cell,
In the isotope gas spectrometry method of measuring the concentration of the component gas by measuring the amount of transmitted light having a wavelength suitable for the component gas and processing the data, the gas to be measured is human breath, Is a carbon dioxide ¹³ CO ₂ , a wavelength suitable for the component gas is about 4412 nm, a gas to be measured is guided to a cell, and a first step of obtaining an absorbance corresponding to the wavelength of the component gas, Using the calibration curve created by measuring the gas containing the component gas, the second step of determining the concentration of the component gas in the gas to be measured, and measuring the concentration of water vapor contained in the gas to be measured, Using a correction line created by measuring a gas having a known concentration, a third correction of the concentration of the component gas according to the measured water vapor concentration.
An isotope gas spectrometry method comprising the step of: 2. An isotope for measuring a concentration ratio of a component gas by introducing a gas to be measured including a plurality of component gases into a cell, measuring the amount of transmitted light having a wavelength suitable for each component gas, and processing the data. In the gas spectrometry method, the gas to be measured is human breath, the plurality of component gases are carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO ₂ , and a wavelength suitable for each of the component gases is carbon dioxide. to ¹² CO ₂
For about 4280Nm, the carbon dioxide ¹³ CO ₂
Is about 4412 nm, the first step of guiding the gas to be measured to the cell and determining the absorbance corresponding to the wavelength of each component gas. The calibration curve created by measuring the gas containing the component gas of a known concentration is represented by Using the second step to determine the concentration ratio of the component gas in the gas to be measured, and a correction line created by measuring the concentration of water vapor contained in the gas to be measured and measuring the gas having a known water vapor concentration And a third step of correcting the concentration ratio of the component gases according to the measured water vapor concentration using the method. 3. The correction line in the third step is to determine the absorbance corresponding to the wavelength of each component gas for a plurality of gases having different water vapor concentrations, and to determine the concentration ratio of each component gas using the calibration curve. , Obtained by plotting the ratio or difference of the concentration ratios of the respective component gases with respect to the water vapor concentration. The correction method in the third step is a method in which the water vapor obtained in the third step for the gas to be measured is obtained. Is applied to the correction line to obtain a concentration ratio correction value of the component gas, and the concentration ratio of the component gas obtained in the second step is divided or subtracted by the concentration ratio correction value obtained from the correction line. 3. The method according to claim 2, wherein
The isotope gas spectrometry described. 4. A gas to be measured containing a plurality of component gases is guided to a cell, the quantity of transmitted light having a wavelength suitable for each component gas is measured, and the measured quantity of light is subjected to data processing by data processing means. in proportional gas spectroscopic measurement apparatus for measuring the concentration ratio of component gases, the measured gas is a breath of a human, said plurality of component gases are carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO _2, the respective wavelength suitable for the component gas, the carbon dioxide ¹² CO ₂
For about 4280Nm, the carbon dioxide ¹³ CO ₂
Is about 4412 nm and transmits light of these wavelengths.
A first wavelength filter and a second wavelength filter, wherein the data processing means obtains an absorbance based on a light amount of light corresponding to a wavelength suitable for each component gas, which is measured for the gas to be measured guided to the cell. An absorbance calculating unit, a concentration calculating unit that obtains a concentration ratio of the component gas in the gas to be measured by using a detection line created by measuring a gas containing a component gas having a known concentration, and a gas to be measured. The concentration ratio of the component gas is corrected according to the measured water vapor concentration using the water vapor concentration measuring means for measuring the water vapor concentration contained in the gas, and the correction line created by measuring the gas having the known water vapor concentration. An isotope gas spectrometer comprising correction means. 5. The first wavelength filter has a bandwidth of about 2
0 nm, and the bandwidth of the second wavelength filter is about
The isotope gas spectrometer according to claim 4, which has a thickness of 50 nm.
Place. 6. An isotope gas for measuring a concentration of a component gas by introducing a gas to be measured including a plurality of component gases into a cell, measuring the amount of transmitted light having a wavelength suitable for each component gas, and processing the data. In the spectroscopic measurement method, the gas to be measured is human breath, the plurality of component gases are carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO ₂ , and a wavelength suitable for each of the component gases is carbon dioxide ¹² to CO ₂
For about 4280Nm, the carbon dioxide ¹³ CO ₂
Is about 4412 nm, the first step of guiding the gas to be measured to the cell and determining the absorbance corresponding to the wavelength of each component gas. The calibration curve created by measuring the gas containing the component gas of a known concentration is represented by Using the second step of determining the concentration of the component gas in the gas to be measured, and measuring the concentration of water vapor contained in the gas to be measured, the correction line created by measuring a gas having a known water vapor concentration The third method is used to correct the concentration of the component gas according to the measured water vapor concentration.
An isotope gas spectrometry method comprising the step of: 7. The correction line in the third step is as follows: for a plurality of gases having different water vapor concentrations, the absorbance corresponding to the wavelength of each component gas is obtained, and the concentration of each component gas is obtained using the calibration curve. The obtained ratio or difference of the concentration of each component gas is obtained by plotting the ratio with respect to the water vapor concentration. The correction method in the third step is a method of correcting the concentration of the water vapor obtained in the third step for the gas to be measured. Is applied to the correction line to obtain a concentration correction value of the component gas, and the concentration of the component gas obtained in the second step is divided or subtracted by the concentration correction value obtained from the correction line. Item 6. The isotope gas spectrometry method according to Item 5. 8. A gas to be measured containing a plurality of component gases is guided to a cell, the quantity of transmitted light having a wavelength suitable for each component gas is measured, and the measured quantity of light is subjected to data processing by data processing means. in proportional gas spectroscopic measurement apparatus for measuring the concentration of a component gas, the measurement gas is the breath of a human, said plurality of component gases are carbon dioxide ¹² CO ₂ and carbon dioxide ¹³ CO _2, the respective components wavelength suitable for gas, carbon dioxide ¹² CO ₂
For about 4280Nm, the carbon dioxide ¹³ CO ₂
Is about 4412 nm and transmits light of these wavelengths.
A first wavelength filter and a second wavelength filter, wherein the data processing means obtains an absorbance based on a light amount of light corresponding to a wavelength suitable for each component gas, which is measured for the gas to be measured guided to the cell. Absorbance calculation means, concentration calculation means for obtaining the concentration of the component gas in the gas to be measured using a detection line created by measuring a gas containing a component gas of a known concentration, A water vapor concentration measuring means for measuring the water vapor concentration contained, and a correcting means for correcting the concentration of the component gas according to the measured water vapor concentration using a correction line created by measuring a gas having a known water vapor concentration. An isotope gas spectrometer comprising: 9. The method according to claim 1, wherein the first wavelength filter has a bandwidth of about 2
0 nm, and the bandwidth of the second wavelength filter is about
9. The isotope gas spectrometer according to claim 8, which has a thickness of 50 nm.
Place.