JP2747933B2 - Concentration measuring method and concentration measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The first invention and the second invention relate to a method for measuring the concentration of a substance to be measured in a test solution, and the third to eighth inventions relate to the method. An apparatus for performing the same.

INDUSTRIAL APPLICABILITY The present invention is used for process control, environmental measurement or medical diagnosis, measurement, and the like of food, medicine, agriculture, animal husbandry, and fisheries, and further, for example, a biosensor for measuring the concentration of glucose and the like.

[Conventional technology]

Conventional methods for measuring and measuring the concentration of a substance to be measured include a method and an apparatus using an electric method of an electric current measuring method and an electric potential measuring method, or a substance that emits or emits light, and is absorbed or absorbed by a photomultiplier tube, a photodiode, or the like. An optical method and an apparatus for obtaining the concentration of a predetermined substance from the intensity of an emission spectrum or the like are known.

[Problems to be solved by the invention]

The measuring method and apparatus using the above-mentioned electric method are susceptible to electric noise and require a precise measuring apparatus. Further, the measuring method and the apparatus by the above-mentioned optical method require a special coloring agent and require a precise and expensive measuring instrument. Furthermore, neither method is suitable for continuous measurement.

The present invention has been made in view of the above-mentioned viewpoints, and generates a refractive index distribution in a radial direction of a fluid inside a tubular body by heat generation, heat absorption, or substance concentration distribution due to a catalytic reaction on an outer wall or an inner wall, thereby forming the refractive index distribution. It has been completed by finding that the convergence state of the passing outgoing light, specifically, the position of the convergence point or the beam diameter at a predetermined position differs depending on the density.

INDUSTRIAL APPLICABILITY The present invention is suitable for continuous measurement, is less susceptible to electric noise, is simple and inexpensive, can be applied to many reaction systems, is less susceptible to fluctuations in illuminance of a light source, unexpected mixing of small bubbles, and the like. It is an object of the present invention to provide a concentration measurement method and a device thereof that can remotely control a process as needed.

[Means for solving the problem]

"At least the outer wall or the inner wall has a catalyst" of the first invention, "At least the outer wall has a catalyst" of the third invention and "At least the inner wall has a catalyst" of the fourth invention are The catalyst layer may be formed on the outer peripheral surface or the inner peripheral surface of the tubular body, or the tubular body itself may be composed of a catalyst substance. The catalyst layer or the tubular body itself may be composed only of a catalyst substance or may be composed mainly of a catalyst. When this catalyst layer is formed, it is usually coated on the outer wall surface or inner wall surface that comes into contact with the test liquid, but it may be a part of the outer wall surface or the outer peripheral surface that does not come into contact with the test liquid. There may be. The thickness, porosity, formation method, and the like of the coating layer are not limited.

In the first invention, the “fluid” flowing through the tubular body is a medium or a test liquid. When the catalyst has a catalyst on at least the inner wall of the tubular body, the test liquid as a fluid flows through the tubular body, and when the catalyst has a configuration other than that, a medium as the fluid flows through the tubular body. Here, the medium widely refers to a medium that does not react with the catalyst.

In the third aspect, in the case of a tubular body having a catalytic action, when a catalytic reaction occurs with a fluid inside the tubular body, a coating film may be formed on an inner wall of the tubular body to prevent the catalytic reaction.

In the apparatus according to the fifth aspect of the present invention, the catalytic reaction means is provided outside the outer frame and connected to an inlet of the outer frame. The form of the "catalytic reaction means" is not particularly limited, but usually, a container is filled with a large number of granular articles having a predetermined catalyst supported on a predetermined carrier, or a honeycomb-shaped body having a catalyst supported on an inner wall thereof. Is used.

In the apparatus according to the sixth aspect of the present invention, the catalyst reaction means comprises a catalyst body filled and held between the tubular body and the outer frame body (this is a carrier in which a catalyst is carried on a carrier). The catalyst body used in the fifth invention is also used.

The apparatus according to the seventh aspect of the present invention is characterized in that the catalytic reaction means is disposed in close contact with the outer peripheral surface of the tubular body, and heats or cools the tubular body by performing a catalytic reaction here. The surface to be adhered is usually a partial surface of the tubular body, that is, a lower surface or a semi-peripheral surface thereof. The form of the catalytic reaction means may be the one described in the first invention.

The “catalyst” used in the first to eighth inventions can be appropriately selected according to the type of the substance to be measured. For example, enzymes such as glucose oxidase that oxidizes glucose to produce gluconolactone and hydrogen peroxide, as well as microorganisms and antibodies can be used. The one using this is called a so-called bioreactor and can be applied as a biosensor. It may be of an organic or inorganic reaction type. Further, the reaction may be exothermic or endothermic.

The above “medium” is used except for the case of the fourth invention,
It flows through the above-mentioned tubular body, and is usually a liquid, but may be a gas.

The test liquid flows outside the tubular body in the devices of the third, fifth to seventh inventions, and inside the tubular body in the device of the fourth invention. In the measuring method according to the first invention, it may flow to either one of them.
The fluid flowing inside the tubular body may be a test liquid or a medium such as water.

The outer frame in the third, fifth to seventh inventions may be any as long as it holds or circulates the test liquid, regardless of its shape, size, and the like. Although it is an outer tubular body as shown in FIG. 14 and FIG. 14, it may be a tank or the like.

[Action]

The operation of this measuring method will be described below using, for example, the apparatus of the third invention shown in FIG.

The catalyst 2 immobilized on the outer wall of the tubular body 1 catalyzes the reaction of the substrate (measured substance) contained in the test solution B, and exhibits heat generation or endothermic action. On the other hand, the medium (fluid) A flowing inside the tubular body 1 is heated or cooled from the wall of the tubular body 1. In the case of this heating, the medium undergoes thermal expansion in the peripheral portion, and has a lower density than the medium in the central portion. In the case of cooling, the opposite tendency occurs. Therefore, as shown in FIG. 7, a density distribution, that is, a refractive index distribution, is generated symmetrically with respect to the central axis of the tubular body. FIG. 2A shows the case of heating, and FIG. 2B shows the case of cooling.

Then, as shown in FIG. 4, the light incident on the medium A is
In the case of FIG. 7 (a), the light is bent inward, and the emitted light is taken out from the other end of the tubular body.
_It converges at ₀ . In the case of Figure 7 (b), by but are bent outward to interpose a convex lens 9 as shown in FIG. 11 or the like, emitted light is converged at a certain position P _O. The position of the convergence point of the emitted light is measured, for example, by finding a position where the energy density of the emitted light is highest in the emission direction. The convergence state of the emitted light is
Not only the convergence point position but also the detection can be performed based on the beam diameter of the light emitted from the light receiving unit. The degree of change in the position of the convergence point of the emitted light and the like differs depending on the concentration of the measured object.

As described above, since the amount of change and the concentration of the object to be measured show a fixed relationship, the concentration can be measured by detecting the amount of change.

In the device of the fourth invention, as shown in FIG.
While the test liquid B passes through the inside of the tubular body 1, a catalytic reaction occurs at the interface between the inner wall and the liquid. In this case, the disappearance of the reactants and the generation of products occur, and the concentration of each substance is A
Speaking of the reaction of + B → C + D equation, for example, FIG.
As shown in (d), each substance has a predetermined concentration distribution in the radial direction. As a result, due to the difference in diffusivity of each substance, the reactant and the product as a whole are in the radial direction of the tubular body. Has a distribution of the refractive index. This distribution differs depending on the reaction system or the type of the reactant or the product, the degree of diffusion, etc., and further includes the effect of heat generation and heat absorption accompanying the reaction. For example, as shown in FIG. 7 (a) or (b) Distribution. Therefore, also in this case, similarly, since the concentration of the measured object and the position of the convergence point have a fixed relationship,
It can be measured similarly.

〔Example〕

 Hereinafter, the present invention will be described specifically with reference to examples.

Example 1 In this example, a catalyst is provided on the outer wall of a tubular body, and a glucose concentration is measured by detecting a convergence point of emitted light.

(1) Apparatus Configuration and Manufacturing Method As shown in FIG. 1 and FIG. 2, this apparatus comprises an inner tubular body 1, a catalyst layer 2, a medium introducing means 3, a medium deriving means 4, and an outer frame body. It comprises a tubular body 5, a He-Ne laser 6, and a convergence point detecting means 7.

The inner tubular body 1 is an alumina tube having an inner diameter of 1.7 mmφ, an outer diameter of 2.3 mmφ, and a length of 120 mm and having both ends open. This tubular body 1
An enzyme is immobilized on about half of the outer wall at the front end side (test liquid introduction side), and a lead trioxide (Pb ₃ O ₄ ) layer is formed on the rear half. At both ends of the tubular body 1, flanges 31 and 41 disposed on the inside, glass windows 33 and 43 disposed at the ends, and tubular portions 32 and 42 disposed therebetween, and the tubular portions 32 and 42 A medium introduction means 3 or a medium discharge means 4 comprising a medium introduction port 34 or a medium discharge port 44 attached to the side of the medium is detachably attached. The medium A enters the inlet 34 via the filter 81 and the pump 82 and exits from the outlet 44. Note that the introduction and derivation of the medium may be reversed.

The medium A and the test liquid B are each kept at a constant temperature in a constant temperature bath 83.

The He-Ne laser 6 serves as a light emission source, and this laser light is transmitted through the glass window 33 into the inside of the tubular body 1. The convergence point detecting means 7 is arranged on the other side of the glass window 43 side. As shown in FIG. 5, the detecting means 7 comprises an optical meter 72 with an optical fiber 71 for detecting the amount of light flux, a fixture 73 for fixing the optical fiber (core diameter 50 μm), and a caliper 74 for determining the position. . In practice, as shown in FIG. 1, two reflecting mirrors 8a and 8b are provided to reduce the size of the apparatus.

This device was manufactured as follows. That is, first,
Prepare the above alumina tube. Separately, an alumina suspension (alumina particle size: 0.5 μm, alumina purity: 99.95%, water content: 60%) was prepared, and this alumina tube was immersed in the suspension, pulled up, and applied to the outer surface thereof. Next, this was fired in an electric furnace at 1150 ° C. for 3 hours to form a porous film having a thickness of about 10 μm (average pore diameter: 0.21 μm, porosity: 48%).

After that, a suspension of trilead tetroxide (with a particle size of 0.3μ)
m, special grade of reagent, water 40%) is prepared, and about half of the entire length of the outer surface of the tubular body is dipped and applied. Then, change this to 43
The resultant was fired in an electric furnace at 0 ° C. for 1 hour in an air atmosphere to form a porous lead oxide layer having a thickness of about 3 μm. Further, carbon black (reagent) is thoroughly kneaded with tung oil in a mortar, applied to the inner surface of the tubular body, dried at 60 ° C. for 15 hours,
A black film formed.

Next, the half of the tubular body on the exposed side of the porous alumina is immersed in concentrated hydrochloric acid for 1 hour, and then washed with deionized water. Thereafter, similarly, the exposed side was immersed in an acetone solution of γ-aminopropylethoxysilane having a concentration of 10% for 15 hours,
A silanization treatment was performed.

Next, after taking out this, it was air-dried for 5 hours, and then 5% glutaraldehyde / 0.05M phosphate buffer (pH
7.0) for 4 hours. Further, this was mixed with 60 ml of a 0.05 M phosphate buffer (pH 7.0) containing 1 g of glucose oxidase.
It was immersed in the solution to immobilize the enzyme, thereby producing the inner tubular body 1 with the catalyst 2. Note that at least the windows 33 and 43 on both ends are made of transparent glass or resin. If you want to preserve this enzyme-immobilized tubular body, use 0.5M phosphate buffer (pH 7.
0).

Then, the above-mentioned medium introducing means 3, lead-out means 4 and outer tubular body 5 were assembled to this, and a module M having a double pipe structure shown in FIG. 2 was manufactured. As described above, the introduction and extraction of the medium A or the test liquid B or the introduction and extraction of light can be performed.

In addition, as shown in FIG. 3, the module has a double-tube structure in which window glasses 33 and 43 and an inlet as medium introducing means 3a and an outlet as outlet means 4a are directly attached to the inner tubular body 1a. You can also.

Further, the laser device 6 was disposed on the window 33 on the light introduction side of the module M, and the convergence point position detection device 7 was disposed on the glass window 43 side in the light extraction direction, thereby producing the device. As shown in FIG. 6, reflecting mirrors (two) 8a and 8b were arranged on the exit light side at 45 ° to the optical axis.

On the other hand, a test solution B was prepared by dissolving glucose at various concentrations in a 0.1 M phosphate buffer (pH 7.0).

(2) Measuring method In the above apparatus, isooctane (special grade, 26.0 ° C.) at a rate of 1.4 ml / min is continuously supplied to the medium inlet 34 to flow the liquid inside the tubular body, and various concentrations of glucose solution ( 26.0 ° C.) into the outer tubular body 5 at a flow rate of 3 ml / min.

On the other hand, a helium-neon laser (wavelength 543 nm, output 1 m
The W) causes incident so as to be substantially parallel to the tube axis into the tubular body 1, by the front and rear of the light-receiving surface of the optical fiber, most light energy (the convergence point of the emitted light with high potential energy density) position P _O And

(3) Effect of the Example The test results as described above are shown in FIG. The position of the convergence point in the figure is based on the position at a concentration of 1000 ppm.

Next, as a comparative example, a test was performed in the same manner as in the above example except that the catalyst was not used, and the results are also shown in the same drawing.

As shown in this figure, in the comparative example, even if the glucose concentration was increased, the gradient (change) in the relationship between the convergence point position and the concentration was extremely small, so that sufficient sensitivity to the concentration could not be obtained, and the detection was not possible. Not suitable. On the other hand, in the present example, since a good linear relationship with a large slope was shown in a wide concentration range of 1 to 1000 ppm, glucose concentration could be measured well and sensitively in a wide concentration range, and electrical noise was reduced. Continuous measurement can be performed at a high speed without being affected by the light source, and furthermore, it is hardly affected by fluctuation of the illuminance of the light source, mixing of small bubbles, and the like. In addition, the present device can be simple and small in overall structure, and has a large effect particularly since it has a reflecting mirror.

Embodiment 2 In this embodiment, as shown in FIG.
Enzyme 2 is immobilized on the inner wall of the substrate and a catalytic reaction is performed on the inner wall. The test liquid B flows through the inside of the tubular body 1 and does not include the outer tubular body as in the first embodiment. Others are substantially the same as the first embodiment. In this apparatus, a test liquid inlet 11 is attached to an end side surface near one end of the tubular body 1, and a test liquid outlet 12 is attached to an end side surface near the other end.
Note that the entire tube is covered with a light shielding box 84.

An enzyme (glucose oxidase) is immobilized on the entire inner wall of the tubular body 1 in the same manner as in Example 1, and the glucose concentration is measured in the following biochemical reaction system.

Glucose (A) + O ₂ (B) → gluconolactone (C) + H ₂ O ₂ (D) In this example, the reactants and products are as shown in (a) to (d) of FIG. As shown in FIG. 10 (c), the refractive index distribution as shown in FIG. 7 (b) has a lower inner wall than the center of the tubular body. The side shows a concave distribution in which the refractive index increases.

Therefore, in this embodiment, the convex lens 9 is arranged in front of the module M as shown in FIG. 11 or the convex lens 9 is arranged behind it as shown in FIG. By connecting the convergence points P ₀ , the concentration can be measured in the same manner as in the first embodiment. This embodiment also has the same effect as the first embodiment. As described above, the case of the concave distribution can also be applied.
Very wide application range.

Incidentally, such a concave distribution of the refractive index becomes the same if an endothermic reaction is carried out using the apparatus of the above-mentioned Example 1, so that the concentration can be measured in the same manner.

It should be noted that the present invention is not limited to the specific embodiments described above, but may be variously modified within the scope of the present invention in accordance with the purpose and application. That is, the above-mentioned tubular body may be any as long as it allows fluid to pass therethrough, and its size, length, overall shape, cross-sectional shape, material, and the like can be variously selected depending on the purpose and application. For example, the entire shape may be a curved tube instead of a straight tube, and its cross-sectional shape is usually a perfect circle, but may be a square, a hexagon, an ellipse, etc., and further a honeycomb shape or a lotus root shape May have a plurality of flow path holes. This tubular body is preferably made of a material having good heat conductivity, low specific heat, and low density. This is because the sensitivity is further increased.

As a catalyst, an enzymatic reaction and a hydrogen peroxide decomposition reaction were carried out in one module as in Example 1, and only the former reaction was carried out as in Example 2. It is possible to combine them, to carry out only the latter reaction, or to adopt a catalyst configuration in which both reactions are carried out simultaneously. The medium may be a gas, instead of the liquid as in the first embodiment, or various liquids such as water.

In addition, as a specific example of the device of the fifth invention, as shown in FIG. 13, the catalyst reaction means 20 can be connected to an inlet 51 of a test liquid. At both ends of the tubular body 1,
Light transmission windows 12a and 12b are arranged via the intermediate cylindrical bodies 13a and 13b. This tubular body 1 has an inner diameter of 1.1 mm, an outer diameter of 1.5 mm, and a length of 50 mm
The light transmission windows 12a and 12b are made of quartz glass, and the intermediate cylindrical body 13 is made of an acrylic resin. The intermediate cylinders 13a and 13b are provided with a medium introduction unit 3 and a medium exit unit 4, respectively. Outer frame 5
Is made of an acrylic resin tube, and has a test liquid inlet 51 at one end and a test liquid outlet 52 at the other end. The tubular body 1 is disposed inside the inside. Further, a heat insulating material 53 made of porous polyethylene or the like is provided inside the outer frame 5. The catalytic reaction means 20 includes a box 21 made of an acrylic resin tube, a porous polyethylene cylinder 22 arranged inside the box 21, and a predetermined enzyme (catalyst) filled in the box 21. (Catalyst body) 2 in which is carried on a carrier, so as to form a so-called bioreactor. In this case, the same operation and effect as those of the above embodiment are obtained.

Further, in the apparatus of the sixth invention, as shown in FIG. 14, as the catalyst reaction means 20, the granular material 2B supporting the catalyst used in the above embodiment is placed between the tubular body 1B and the outer frame body 5B. filling,
It is also possible to adopt a configuration in which it is held. In this case, the same operation and effect as those of the above embodiment are obtained.

In the device of the seventh invention, the catalyst reaction means 20C is
As shown in the drawing, a configuration may be employed in which the side surface of the tubular body 1C is separately provided outside the tubular body 1C so that one side surface of the tubular body 1C can be heated or cooled without having the outer frame body. In this case, the tubular body 1C and the catalytic reaction means 20C preferably have a shape that is easy to adhere to each other.For example, in the case of a tubular body having a rectangular cross section, the contact surface is a catalytic reaction means such as a rectangular parallelepiped having a flat surface, In the case of a tubular body having a circular cross section, it is preferable to use a catalytic reaction means or the like in which the contact surface has a semicircular concave shape. In this case, the same operation and effect as those of the above embodiment are obtained.

A light emitting diode can be used as the light emitting element. The method of irradiating light by the light-emitting element may irradiate the entire end surface of the tubular body almost uniformly, may irradiate substantially the center, or may irradiate a place near the tube wall, a place near the center, or the like. it can. In the case of a place near this tube wall, there is an effect of improving the sensitivity. The beam diameter is also selected variously depending on the purpose and the like.

Various known means can be used as the detection means. For example, as a method (apparatus) of detecting the convergence state of the emitted light, not only the convergence point method but also a method of arranging a laser beam analyzer at a predetermined position and detecting a beam diameter at the laser beam analyzer can be used. In addition, these detections can be performed by automatic operation or mechanical operation, instead of manual operation as in the above embodiment. For example, it is possible to automate operations such as movement of a light receiving surface, measurement and storage of received light energy, determination of a convergence point or a beam diameter, conversion into a concentration, and the like. By giving the data, the density data can be automatically calculated and displayed.

Note that the concentration measurement method of the present invention measures the concentration of the object in the liquid to be measured from the convergence state of the emitted light detected by the convergence point position or the beam diameter, etc. Alternatively, a change in the amount of emitted light received at a predetermined position may be detected. Similarly, the concentration measuring device of the present invention may include a detecting unit that detects the amount of emitted light received at a predetermined position in addition to detecting the convergence state based on the convergence point position or the beam diameter. As described above, the sensitivity and reliability of the density measurement can be further improved by detecting the refractive index distribution according to the density of the object to be measured by the two methods of the convergence state and the received light amount.

Optical fibers may be placed on either or both, which is convenient for remote operation. Furthermore, a configuration in which this optical fiber is directly attached to the tubular body, or a configuration in which the element is directly attached may be adopted. The length, thickness, material, form, mounting position, and the like of the optical fiber can be variously selected. For example, the material is not limited to resin but may be glass.

Furthermore, the present invention can be used as a temperature sensor because the refractive index distribution in the radial direction of the medium varies depending on the temperature of the test liquid as well as the concentration measurement.

〔The invention's effect〕

As shown in the above operation, in the present measurement method, the concentration and the position of the convergence point, up to a wide concentration range of the substance for measurement,
Since it shows a good constant relationship with the convergence state such as the beam diameter, especially linearity, it is very convenient for the measurement. In addition, unlike the optical method, continuous measurement can be performed, the measurement is not affected by pH, and is less susceptible to electric noise as compared with the electric method. Therefore, the measurement can be performed stably, and the apparatus is simple and inexpensive. In addition, the catalytic reaction can be freely selected from exothermic and endothermic reactions, and can be applied as long as the exothermic or endothermic reaction occurs, so that a large number of reaction systems can be used, and the applicable range is very wide. Further, by using a medium having different characteristics (for example, specific heat, thermal conductivity, density, thermal expansion coefficient, etc.), a medium having a desired sensitivity can be freely selected.

In addition, the measurement is highly reliable because it is less susceptible to fluctuations in the illuminance of the light source and unexpected mixing of small bubbles and the like. In addition, since a special high-accuracy light receiving element or a stable light source is not required, a simple and inexpensive method can be realized.

Further, when an optical fiber is used, the process can be remotely controlled by extending the optical fiber, which is very useful.

The present invention is a device that can have the above effects,
Extremely useful.

[Brief description of the drawings]

FIG. 1 is a schematic view of a concentration measuring apparatus according to Embodiment 1, and FIG.
FIG. 3 is an explanatory sectional view of a module used in the first embodiment, FIG. 3 is an explanatory sectional view of another module, FIG. 4 is an explanatory view showing a state in which light passing through the tubular body in the first embodiment is converged,
FIG. 5 is an explanatory diagram showing a means for detecting a convergence point position in the first embodiment, FIG. 6 is an explanatory diagram for detecting a convergence point position using a reflecting mirror in the first embodiment, and FIG. Is an explanatory view showing that a refractive index distribution occurs in (a), (a) shows a convex distribution, (b) shows a concave distribution, and FIG. 8 shows the relationship between the glucose concentration and the convergence point position in Example 1. FIG. 9 is an explanatory sectional view of the module used in Example 2, and FIG. 10 is an explanatory view showing that a concentration distribution occurs in the radial direction of the tubular body of each reactant or product. A substance, (B) shows B substance, (C) shows C substance, and (D) shows D substance. Fig. 11 is an explanatory view showing a converged state when the refractive index distribution is concave, and Fig. 12 is refraction. FIG. 13 is an explanatory diagram showing another convergence state when the rate distribution is concave, FIG. 13 is an overall explanatory diagram of the device according to the fifth invention, and FIG. Main part illustration of an apparatus according to the sixth invention, FIG. 15 illustrates the main part of the apparatus according to the seventh invention. 1; tubular body, 2; catalyst (layer, body), 20; catalytic reaction means, 3; medium introducing means, 4; medium outlet means, 5; outer frame (outer tubular body), 6; laser device, 7; Convergent point position detector, 8; reflecting mirror, 9; convex lens, A; medium, B: test liquid.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuyuki Mizushima 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture Inside Japan Specialty Ceramics Co., Ltd. 18 Japan Special Ceramics Co., Ltd. (72) Inventor Junichi Tokumoto 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Special Ceramics Co., Ltd. (56) References JP-A-60-76648 (JP, A) 63-247646 (JP, A) Japanese Patent Publication No. 7-14337 (JP, B2) Patent 2517388 (JP, B2)

Claims (8)

(57) [Claims] (1) (a) a catalyst provided on at least an outer wall or an inner wall of a tubular body, or (b) placed between the tubular body and an outer frame body disposed on an outer peripheral side of the tubular body, or By promoting the reaction of the reactant contained in the test liquid by the catalyst supported on the carrier disposed outside the outer frame, the fluid flowing through the tubular body has a refractive index distribution in the radial direction of the tubular body. While the fluid is flowing through the tubular body, light is incident from one end of the tubular body, and emitted light is taken out from the other end. Thereafter, a convergence state of the emitted light is detected, and the convergence state of the emitted light is detected. Measuring the concentration of the object to be measured. 2. The concentration measuring method according to claim 1, wherein the detection of the convergence state is performed by measuring a convergence point position or a beam diameter of the emitted light. 3. A reaction in a reactant contained in a test solution is promoted by a catalyst to cause a medium in the tubular body to have a refractive index distribution in a radial direction of the tubular body. A concentration measuring device for injecting light into the body, taking out emission light from the other end to the outside, and thereafter detecting a convergence state of the emission light to measure the concentration of the analyte in the test solution, A tubular body having a catalyst on its outer wall that promotes a reaction of a reactant contained in the test solution; an introduction means attached to one end of the tubular body for introducing a medium into the tubular body; A deriving means attached to the other end side for deriving the medium from the tubular body, and holding or flowing the test liquid disposed on the outer peripheral side of the tubular body and in contact with the catalyst to introduce the test liquid. With an inlet for outflow and an outlet for outflow An outer frame, a light emitting element disposed directly or via an optical fiber for light transmission on one end side of the tubular body, and detecting a convergence state of emission light taken out from the other end of the tubular body to the outside. A concentration measuring device comprising: 4. The catalyst promotes a reaction of a reactant contained in the test liquid to cause a refractive index distribution in the test liquid in the tubular body in a radial direction of the tubular body, thereby forming one end of the tubular body. From the other end, emits light to the outside from the other end, and thereafter detects the convergence state of the emitted light to measure the concentration of the analyte in the test solution. A tubular body having a catalyst on at least an inner wall thereof for promoting a reaction of a reactant contained in the test liquid; and an introduction means attached to one end of the tubular body for introducing the test liquid into the tubular body. A deriving means attached to the other end of the tubular body for deriving the test liquid from the tubular body; and a light emitting element disposed directly or via an optical fiber for light transmission on one end of the tubular body. And convergence of the emitted light taken out from the other end of the tubular body Concentration measuring apparatus characterized by comprising detecting means for detecting a condition, a. 5. A catalyst which promotes the reaction of a reactant contained in a test liquid to cause a medium in the tubular body to have a refractive index distribution in a radial direction of the tubular body. A concentration measuring device for injecting light into the body, taking out emitted light from the other end to the outside, and thereafter detecting a convergence state of the emitted light to measure the concentration of the test object in the test liquid, A tubular body that holds or circulates the fluid; an introduction means attached to one end of the tubular body to introduce the medium into the inside of the tubular body; and a medium attached to the other end of the tubular body from the tubular body. An outer frame body provided on the outer peripheral side of the tubular body and having an inlet for introducing a test liquid and an outlet for extracting the test liquid, and an outer frame body arranged outside the outer frame body. Connected to the inlet of the outer frame to perform a catalytic reaction. A light emitting element disposed directly or via an optical fiber for light transmission on one end side of the tubular body, and a light emitting element taken out from the other end of the tubular body to the outside. A concentration measuring device comprising: a detecting unit that detects a convergence state. 6. The catalyst promotes the reaction of a reactant contained in the test liquid to cause a medium in the tubular body to have a refractive index distribution in a radial direction of the tubular body, and to cause the tubular body to have a refractive index distribution from one end of the tubular body. A concentration measuring device for injecting light into the body, taking out emitted light from the other end to the outside, and thereafter detecting a convergence state of the emitted light to measure the concentration of the test object in the test liquid, A tubular body that holds or circulates, an introduction means attached to one end of the tubular body to introduce a medium into the inside of the tubular body, and a medium attached to the other end of the tubular body. A deriving means for deriving, an outer frame body provided on the outer peripheral side of the tubular body and having an inlet for introducing a test liquid and an outlet for deriving the test liquid, and the outer frame and the tubular body Equipped with a catalyst that performs a catalytic reaction filled and held between the bodies Catalytic reaction means, a light emitting element disposed directly or via an optical fiber for light transmission on one end side of the tubular body, and detecting a convergence state of emitted light taken out from the other end of the tubular body to the outside. A concentration measuring device comprising: 7. A catalyst which promotes the reaction of a reactant contained in a test liquid to cause a medium in the tubular body to have a refractive index distribution in a radial direction of the tubular body, and from one end of the tubular body to the tubular body. A concentration measuring device for injecting light into the body, taking out emitted light from the other end to the outside, and thereafter detecting a convergence state of the emitted light to measure the concentration of the test object in the test liquid, A tubular body that holds or circulates the fluid; an introduction means attached to one end of the tubular body to introduce the medium into the inside of the tubular body; and a medium attached to the other end of the tubular body from the tubular body. A deriving means for deriving a test solution, a catalyst for causing a catalytic reaction to be provided in close contact with the outer peripheral surface of the tubular body, an inlet for introducing a test solution, and a guide for deriving the test solution. Catalytic reaction means having an outlet, on one end side of the tubular body, A light-emitting element disposed in contact with or via a light-transmitting optical fiber; and detecting means for detecting a convergence state of emitted light taken out from the other end of the tubular body to the outside. Concentration measuring device. 8. The apparatus according to claim 3, wherein said detecting means detects said convergence state by measuring a convergence point position or a beam diameter of said emission light. Concentration measuring device.