JP2996611B2 - Isotope gas spectrometer - 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 and apparatus 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, and 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, the aforementioned Japanese Patent Publication No. Sho 6
In the method described in Japanese Patent No. 1-442220, an air space exists instead of the shortened cell, and this space has been an obstacle to realizing high-accuracy measurement. Also, the space from the light source to the cell and the space from the cell to the light receiver can be considered to be an obstacle to realizing high-accuracy measurement if the length is long.

That is, in the measurement of the isotope gas, the optical absorption of ¹³ CO ₂ present in the measurement is measured. Therefore, even if a slight disturbance is present, the measurement accuracy is greatly deteriorated. The space existing in place of shortening the cell as described above, the space from the light source to the cell, and the space from the cell to the light receiver have some percentage of
^{There are 12} CO ₂ and traces of ¹³ CO ₂ . ^Since the spectrum of ¹² CO ₂ partially overlaps with the spectrum of ¹³ CO ₂ , and when the interference filter is used, the band pass width of the filter is also affected.Therefore, the presence of ¹² CO ₂ affects the absorbance measurement of ¹³ CO ₂ , and the trace ¹³ CO ₂ directly affects ¹³ CO ₂ absorbance measurement.

Therefore, in order to avoid the influence of CO ₂ existing in the optical path, each element such as a light source, a sample cell, a reference cell, a wavelength filter, and a detecting element is housed in a sealed case, and the sealed case and the CO ₂ absorbent are separated. A device that removes CO ₂ from the air in the sealed case by connecting the container of the stored power ram with a circulation pump and a tube and circulating the air in the sealed case between the sealed case and the column container has been proposed. (See Japanese Patent Publication No. 3-31218).

In the device described in this publication, the measurement is adversely affected.
Give CO_TwoCan be removed, but CO _TwoWe stored absorbent
Column, tube, and a large sealed case for each element
Required, and the device configuration becomes large. Also, large
The case is sealed to make it a closed structure.
It takes time to make. In addition, air is uneven in the sealed case
Due to local temperature changes and concentration
Causes fluctuations in the light detection signal.
You.

Therefore, the present invention providescarbon dioxide ¹² CO
_Two And carbon dioxide ¹³ CO _Two IsAn object containing multiple component gases
When introducing the measurement gas to the cell and performing spectroscopic measurement,
Accurate measurement of gas concentration with simple equipment
To realize an isotope gas spectrometer capable of
And

[0012]

According to the first aspect of the present invention, there is provided an isotope gas spectrometer for measuring a gas to be measured, wherein a cell for guiding a gas to be measured is disposed in an optical path between a light source and a light receiver. In addition, a reference cell that satisfies a reference gas that does not absorb light having the wavelength to be measured is arranged in a portion of the optical path other than the cell ,
Always keep the reference gas being measured in the reference cell.
Gas flow generating means for flowing at a constant flow rate is provided .

According to the above configuration, since the reference cell that satisfies the reference gas that does not absorb the light of the wavelength to be measured is disposed, it is as if there is no reference cell and only air exists. In addition, the inconvenience that the gas of the same type as the gas to be measured remaining in the measurement container adversely affects optical properties is eliminated. Therefore, more accurate concentration measurement can be performed.

Further, in the isotope gas spectrometer according to the second aspect, the two cells for guiding the gas to be measured are arranged in parallel in the optical path between the light source and the light receiver, and the two cells are Different length, between the shorter cell and the receiver,
Alternatively, between the light source and the shorter cell, a reference cell that satisfies a reference gas that does not absorb light of the wavelength to be measured is disposed, and the reference cell
Gas that constantly flows the reference gas during measurement at a constant flow rate
A flow generating means is provided .

If the lengths of the cells are different, a large space is formed between the shorter cell and the receiver or between the light source and the shorter cell, and the same type as the gas to be measured existing in this space. Gases adversely affect optical measurements. Therefore, by arranging in this space a reference cell that satisfies a reference gas that does not absorb light having the wavelength to be measured, more accurate concentration measurement can be performed.

Further, the isotope gas spectrometer according to claim 1 or 2 is provided with a gas flow generating means for constantly flowing a reference gas at a constant flow rate in a reference cell.
As described above, the reason for flowing the reference gas into the reference cell is that if the reference gas is sealed and used in the reference cell, the reference gas may gradually leak from the joint portion of the cell and be replaced with outside air. This is because, when outside air enters the cell, the same kind of gas as the gas to be measured is present in the cell and adversely affects optical properties. Further, since the reference gas is always supplied at a constant flow rate, non-uniform convection does not occur in the reference cell. Therefore, no fluctuation of the light detection signal occurs.

The gas flow generating means may be a combination of a valve, a pipe, and a flow meter for guiding a reference gas contained in a cylinder. Further, the isotope gas spectrometer according to claim 3 further comprises a temperature holding means for keeping the temperature of the cell for guiding the gas to be measured and the temperature of the reference cell constant. By keeping the temperature in the cell reference cell for guiding the gas to be measured constant, there is no difference between the temperature of the gas to be measured and the temperature of the reference gas, and the thermal conditions can be the same. Therefore, an accurate absorbance can be obtained.

[0018]

[0019]

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
When spectroscopically measuring the concentration of the embodiment of the present invention,
This will be described in detail with reference to the accompanying drawings. 1. 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 may be about 250 ml. Thereafter, a urea diagnostic agent was orally administered and 10-1
Five minutes later, the breath is collected in a breath bag in the same manner as before administration.

The breath bags before and after the administration are respectively set to predetermined nozzles of an isotope gas spectrometer, and the following automatic measurement is performed. II. FIG. 1 is a block diagram showing the overall configuration of an isotope gas spectrometer. The exhalation bag that collects exhaled air after administration (hereinafter referred to as “sample gas”) and the exhalation bag that collects exhaled air before administration (hereinafter referred to as “base gas”) are set in nozzles N ₁ and N ₂ , respectively. The nozzle N ₁ is connected to a three-way valve V ₁ through a transparent resin pipe (hereinafter simply referred to as “pipe”), and the nozzle N ₂ is connected to a 30,000 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 divided into two-way, one enters a reference cell 11c through the flow meter M _1, the other leads to the three-way valve V ₃ through the flow meter M _2. The reference gas enters the reference cell 11c and exits from the reference cell 11c and is discharged as it is.

[0022] While the divided from way valve V ₃ leads to the three-way valve V _1, and the other thereof is connected to the first sample cell 11a for measuring the absorption of ¹² CO _2.
Also, while the divided from way valve V ₂ are two-way leads to the first sample cell 11a through a valve V _4, the other is connected to the three-way valve V _1. Furthermore, between the three-way valve V ₃ and the first sample cell 11a, the gas injector 21 for quantitatively injecting the sample gas or base Sugasu (volume 60 cc) is interposed. The gas injector 21 is shaped like a syringe having a piston and a cylinder. The piston is driven by a motor (not shown), a feed screw connected to the motor, and a nut fixed to the piston. Done by

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. The reference gas is guided to the reference cell 11c and exhausted. The length of the first sample cell 11a is specifically 13 mm, and the length of the second sample cell 11a is 11 mm.
The length of b is specifically 250 mm, and the length of the reference cell 11c is specifically 236 mm.

Reference symbol L indicates an infrared light source device. The infrared light source device L has two waveguides 23 for irradiating infrared light.
a and 23b. The method of generating infrared rays may be any method, for example, a ceramic heater (surface temperature 45 ° C).
0 ° C.) can be used. In addition, a rotating chopper 22 that cuts off and passes infrared rays at a constant cycle is provided. Of the infrared rays emitted from the infrared light source device L,
An optical path formed by an object passing through the first sample cell 11a and the reference cell 11c is referred to as a “first optical path”,
The optical path formed by the object passing through the sample cell 11b is referred to as “second
(See FIG. 2).

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;
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, and the parts of the detecting elements in the packages 26a and 26b are maintained at 0 ° C. by a Peltier element.

FIG. 2 is a sectional view showing the detailed structure of the cell chamber 11. As shown in FIG. The cell chamber 11 itself is made of stainless steel, and is vertically and horizontally sandwiched between metal plates (for example, brass plates) 12, and is sealed by a heat insulating material 14 such as styrene foam through heaters 13 installed vertically or horizontally. I have. Also,
Although not shown in the figure, a temperature sensor (for example, a platinum temperature sensor) for measuring the temperature of the cell chamber 11 is attached.

The inside of the cell chamber 11 is divided into two stages, one of which is a first sample cell 11a and the other is a reference cell 1.
1c and the second sample cell 11
b is arranged. A first optical path passes in series between the first sample cell 11a and the reference cell 11c.
A second optical path passes through the sample cell 11b. Reference numerals 15, 16 and 17 are sapphire transmission windows for transmitting infrared rays.

FIG. 9 is a block diagram showing a mechanism for adjusting the temperature of the cell chamber 11. As shown in FIG. The temperature adjustment mechanism is provided in the cell chamber 11
Temperature sensor 32 attached to the
And a heater 13. As a method of adjusting the temperature of the temperature adjustment substrate 31, any method may be employed. For example, a method of changing a duty ratio of a pulse current flowing through the heater 13 based on a temperature measurement signal of the temperature sensor 32 may be used. Based on this temperature adjustment method, the cell chamber 11 is controlled by the heater 13 so as to be maintained at a constant temperature (40 ° C.). III. Measurement procedure Measurement is performed in the following order: reference gas measurement → base gas measurement → reference gas measurement → sample gas measurement → reference gas measurement →.

During the measurement, a reference gas is constantly flowing through the reference cell 11c, and its flow rate is measured by the flow meter M.
₁ is set so that it is always kept constant. III-1. Reference Measurement As shown in FIG. 3, a clean reference gas is flowed at 200 ml / min for about 15 seconds into the gas flow path and the cell chamber 11 of the isotope gas spectrometer to clean the gas flow path and the cell chamber 11. .

Next, as shown in FIG. 4, the reference gas is flowed while changing the gas flow path, and the gas flow path and the cell chamber 11 are cleaned. After about 30 seconds, each detection element 25
The light quantity is measured by a and 25b. The reason for performing the reference measurement in this way is to calculate the absorbance. In this manner, the amount of light obtained by the first detection element 25a is ¹² R ₁ , and the amount of light obtained by the second detection element 25b is
¹³ written as R _1. III-2. Base Gas Measurement Next, the base gas is sucked from the expiration bag by the gas injector 21 so that the reference gas does not flow through the first sample cell 11a and the second sample cell 11b (FIG. 5).
reference).

After the base gas has been sucked in, the base gas is mechanically pushed out at a constant flow rate using the gas injector 21 as shown in FIG. During this time, each detection element 25
The light quantity is measured by a and 25b. In this way,
The amount of light obtained by the first detection element 25a ¹² B, write the resulting quantity and the ¹³ B in the second detection element 25b. III-3. Reference measurement The gas flow path and the cell are washed again, and the light quantity of the reference gas is measured again (see FIGS. 3 and 4).

Thus, the light amount obtained by the first detection element 25a is written as ¹² R ₂ , and the light amount obtained by the second detection element 25b is written as ¹³ R ₂ . III-4. Sample gas measurement The sample gas is sucked from the expiration bag by the gas injector 21 so that the reference gas does not flow through the first sample cell 11a and the second sample cell 11b (see FIG. 7).

After the sample gas has been sucked, the sample gas is mechanically pushed out at a constant speed using a gas injector 21 as shown in FIG. During this time, each detection element 2
The light quantity is measured by 5a and 25b. In this manner, the amount of light obtained by the first detection element 25a ¹² S, second
The amount of light obtained by the detection element 25b are the ¹³ S. III-5. Reference measurement The gas flow path and the cell are washed again, and the light quantity of the reference gas is measured again (see FIGS. 3 and 4).

The amount of light obtained by the first detection element 25a is written as ¹² R ₃ , and the amount of light obtained by the second detection element 25b is written as ¹³ R ₃ . IV. Data processing IV-1. Calculation of absorbance of base gas First, the transmitted light amount of the reference gas ¹² R ₁ ,
^{Using 13} R ₁ , the transmitted light amount of the base gas ¹² B, ¹³ B, and the transmitted light amount of the reference gas ¹² R ₂ , ¹³ R ₂ , the absorbance of ¹² CO ₂ in the base gas, ¹² Abs (B) and ¹³ CO ₂ The absorbance is determined as ¹³ Abs (B).

[0036] Here, ¹² CO ₂ absorbance ¹² Abs (B) is obtained in ¹² Abs (B) = -log _{^{[2 12 B / (12 R 1}} + 12 R 2) ], ¹³ CO ₂ absorbance ¹³ abs (B) is obtained by ¹³ abs (B) = -log _{^{[2 13 B / (13 R 1}} + 13 R 2) ].

As described above, when calculating the absorbance, the average value (R ₁ + R) of the light amounts of the reference measurements performed before and after
₂ ) / 2, the absorbance is calculated using the average value and the amount of light obtained in the base gas measurement, so that the influence of drift (time change affects the measurement) must be offset. Can be. Therefore, the measurement can be started immediately without having to wait for complete thermal equilibrium (usually several hours) when the apparatus is started. IV-2. Calculation of Absorbance of Sample Gas Next, the transmitted light amount of the reference gas ¹² R ₂ ,
^{Using 13} R ₂ , the amount of transmitted light of the sample gas ¹² S, ¹³ S, and the amount of transmitted light of the reference gas ¹² R ₃ , ¹³ R ₂ , the absorbance of ¹² CO ₂ in the sample gas, ¹² Abs (S), and ¹³ CO ₂
Absorbance ¹³ Request and Abs (S).

[0038] Here, ¹² CO ₂ absorbance ¹² Abs (S) is, ¹² Abs (S) = determined in -log _{^{[2 12 S / (12 R 2}} + 12 R 3) ], ¹³ CO ₂ absorbance ¹³ abs (S) is calculated by ¹³ abs (S) = -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.

The calibration curve, ¹² CO ₂ and the measurement gas of known concentration, using the measured gas of known ¹³ CO ₂ concentration is created. In order to obtain a calibration curve, the absorbance of ¹² CO ₂ is measured by changing the concentration of ¹² CO _{2 in} the range of about 0% to 6%. 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%.
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_TwoWhen¹²CO_TwoThe 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 ¹³ Conc (B) / ¹² Conc (B)
^{+ 13 Conc (B), 13} Conc (S) / 12 Conc (S) + 13 may be defined as Conc (S). ^{This is because} the concentration of ¹² CO ₂ is much higher than the concentration of ¹³ CO ₂ , so that both have substantially the same value. IV-5. ¹³ C ¹³ C variation in comparing the variation of the determined sample gas collected by base Sugasu of is obtained by the following expression. Δ ¹³ C = [concentration ratio of sample gas−concentration ratio of base gas] × 10 ³ / [concentration ratio of base gas] (unit: per mille (per thousand))

[0045]

As described above, according to the first aspect of the present invention, the cell for guiding the gas to be measured is arranged on the optical path between the light source and the light receiver, and the cell on the optical path other than the cell is provided. In the part, a reference cell that fills a reference gas that does not absorb light of the wavelength to be measured is arranged, so that the reference cell is left in the measurement container as if there was no air and there was simply air The inconvenience that the same type of gas as the gas to be measured adversely affects optical properties is eliminated. Therefore, more accurate concentration measurement can be performed.

According to the second aspect of the present invention, the two cells for guiding the gas to be measured are arranged in parallel with the optical path between the light source and the light receiver, and the two cells have a length. Differently, between the shorter cell and the light receiver, or between the light source and the shorter cell, a reference cell that fills a reference gas that does not absorb light having the wavelength to be measured is arranged. Therefore, the same kind of gas as the gas to be measured existing in a large space formed between the shorter cell and the receiver or between the light source and the shorter cell can be prevented from adversely affecting the optical measurement. , More accurate concentration measurement can be performed.

According to the first or second aspect of the present invention, the reference gas is always supplied at a constant flow rate into the reference cell, so that the reference gas is sealed and used in the reference cell. There is no danger that the reference gas will gradually leak from the joint part and be replaced with outside air, and the reference gas can always be filled in the reference cell. Further, since the reference gas is always supplied at a constant flow rate, non-uniform convection does not occur in the reference cell, and fluctuation of the light detection signal does not occur.

According to the third aspect of the invention, since the temperature of the cell for guiding the gas to be measured and the reference cell can be kept constant, the temperature of the gas to be measured and the temperature of the reference gas become equal, and Target conditions can be the same, and accurate absorbance can be determined.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing the structure of a cell chamber.

FIG. 3 is a view showing a gas flow of the isotope gas spectrometer and a gas flow path at the time of cleaning by flowing a clean reference gas through a cell chamber.

FIG. 4 is a diagram showing a gas flow path when a clean reference gas is flown through a gas flow path and a cell chamber of the isotope gas spectrometer for cleaning and reference measurement.

FIG. 5 is a diagram illustrating a first sample cell 11a having a reference gas;
FIG. 9 is a flow chart showing a state in which a base gas is inhaled by a gas injector 21 from an expiration bag without flowing through a second sample cell 11b.

FIG. 6 is a drawing illustrating a method of mechanically extruding a base gas at a constant speed using a gas injector 21 after inhaling a base gas. During this time, a gas flow path for measuring the amount of light from each of the detection elements 25a and 25b is formed. FIG.

FIG. 7 shows a first sample cell 11a having a reference gas;
FIG. 9 is a flow chart showing a state in which a sample gas is being sucked in from a breath bag by a gas injector 21 so as not to flow through a second sample cell 11b.

FIG. 8 shows a gas injector 21 after aspirating a sample gas.
Mechanically extruding the sample gas at a constant speed using
FIG. 4 is a diagram showing gas flow paths when measuring the amount of light by the detection elements 25a and 25b during this time.

FIG. 9 is a block diagram showing an outline of a mechanism for adjusting the temperature of the cell chamber.

[Explanation of symbols]

D Infrared detector L Infrared light source device M ₁ , M ₂ Flow meter N ₁ , N ₂ nozzle V ₁ -V ₄ valve 11a First sample cell 11b Second sample cell 11c Reference cell 21 Gas injector 24a First wavelength filter 25a first detection element 24b second wavelength filter 25b second detection element 31 temperature adjustment board 32 temperature sensor

──────────────────────────────────────────────────続 き Continuing from the front page (72) Eiji Ikegami, Inventor 112, Tonasaka, Mizuguchi-cho, Koka-gun, Shiga Prefecture (72) Inventor Kazunori Tsutsui 670, Mizuguchi, Mizuguchi-cho, Koka-gun, Shiga Prefecture 38 (56) References JP 7 JP-A-190930 (JP, A) JP-A-56-66738 (JP, A) JP-A-1-61647 (JP, U) JP-A-57-205056 (JP, U) JP-B-61-42220 (JP, B2) (JP) B-48822 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/00-21/61 G01N 33/497 JICST file (JOIS)

Claims (3)

(57) [Claims] An isotope gas for measuring a concentration of a component gas by introducing a gas to be measured containing 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 spectrometer, the plurality of component gases may include carbon dioxide ¹² CO ₂ ,
Carbon ¹³ CO ₂ , the cell for guiding the gas to be measured is arranged in the optical path between the light source and the light receiver, and the other part of the optical path, other than the cell, has light for the wavelength to be measured. A reference cell that satisfies the non-absorbable reference gas is arranged, and the reference gas being measured is constantly stored in the reference cell.
An isotope gas spectrometer comprising a gas flow generating means for flowing at a constant flow rate . 2. A method for measuring a concentration of a component gas by introducing a gas to be measured including a plurality of component gases into two cells, measuring the amount of transmitted light having a wavelength suitable for each component gas, and processing the data. In the body gas spectrometer, the plurality of component gases may be carbon dioxide ¹² CO ₂ ,
The two cells , which are carbon ¹³ CO ₂ and guide the gas to be measured , are arranged in parallel in the optical path between the light source and the light receiver, and have different lengths of the two cells. between the light receiver, or between the light source and the shorter cell, reference cell satisfies a reference gas having no absorption with respect to light having a wavelength to be measured is arranged, measured in the reference in the reference cell Gas always
An isotope gas spectrometer comprising a gas flow generating means for flowing at a constant flow rate . 3. The isotope gas spectrometer according to claim 1, further comprising temperature holding means for keeping the temperature of the cell for guiding the gas to be measured and the reference cell constant.