JPH0714337B2 - Concentration measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for measuring the concentration of a reaction product or a product in a test solution, and more specifically, it has no limitation on pH and is used for continuous measurement. The present invention relates to a suitable concentration measuring device. INDUSTRIAL APPLICABILITY The present invention is used for process control in chemistry, pharmaceuticals, food industry, environmental measurement or medical diagnosis, measurement, and the like, and further for a biosensor for measuring the concentration of glucose and the like.

[Conventional technology]

As a conventional concentration measuring device for a reaction product or a product, a substance which develops or emits light by this substance is used, and the concentration of a predetermined substance is obtained from the intensity of an absorption spectrum or an emission spectrum by a photomultiplier tube, a photodiode or the like. Are known.

[Problems to be Solved by the Invention]

The above-mentioned conventional device has a limitation on the pH of the test liquid and is not suitable for continuous measurement.

The present invention has been made in view of the above viewpoint, and changes the propagation characteristics of light by causing a refractive index distribution in the radial direction of the tubular body as a whole of the reaction product and the product due to the catalytic reaction on the inner wall. It was completed by finding that.

It is an object of the present invention to provide a concentration measuring device which has no restriction on the pH of a test liquid, is suitable for continuous measurement, is less susceptible to electrical noise, and can remotely control a process as needed.

[Means for Solving the Problems]

An apparatus for measuring a concentration of a reaction product or a product in a test liquid according to the present invention is characterized by including a tubular body, a light emitting element and a light receiving element, and the tubular body has a predetermined catalyst only on an inner wall. A light-emitting element having an inlet for introducing the test liquid and a lead-out port for leading the test liquid, wherein the light-emitting element is directly on one end side of the tubular body located on the inlet side or the outlet side, or The light receiving element is arranged via the light transmitting optical fiber, and the light receiving element is arranged directly or through the light receiving optical fiber on the other end side of the tubular body positioned on the outlet side or the inlet side. It

The tubular body only needs to have the catalyst on the inner wall, and a coating film may be formed on the inner wall of a predetermined tubular body using only the catalyst or a composition mainly containing the catalyst.

This catalyst promotes the reaction of the reaction product in the test liquid, and is appropriately selected depending on the type of the reaction substance. Further, it may be a biochemical reaction catalyst such as a glucose oxidase catalyst that oxidizes glucose to produce gluconolactone and hydrogen peroxide, or an organic or inorganic reaction system. When this coating layer is formed, it can be formed on a predetermined portion of the tubular body, and is usually coated on the entire inner wall surface, but it may be a portion thereof, and the formation method is also It doesn't matter.

[Action]

While the test liquid passes through the inside of the tubular body, a catalytic reaction occurs at the interface between the inner wall and the liquid. In this case, the reaction product disappears and the product is generated, and the concentration of each substance is A + B →
Speaking of the reaction of C + D type, for example, FIG. 2 (A) to (D)
As shown in, each substance shows a predetermined concentration distribution in the radial direction. Then, due to the difference in diffusivity of each substance, the reaction product and the product as a whole have a distribution of refractive index in the radial direction of the tubular body. This distribution differs depending on the reaction system or the type of the reaction product or product, the degree of diffusion, etc., and is, for example, the distribution shown in FIG. 3 (a) or (b).

Then, as shown in FIG.
In the case of the distribution of the light shown in FIG.
Bent outward, the amount of permeation and absorption on the inner wall 2 increases,
The amount of light received decreases. On the other hand, in the case of (b) in the same figure, it is bent inward and absorption and scattering on the wall surface are reduced, and the number of reflections is also reduced, which is the opposite relationship to the above. For comparison, a conventional example having no refractive index distribution is shown by dotted lines (a ') and (b').

As described above, in the case of the present invention, since the refractive index distribution is in the radial direction, the amount of light transmission increases or decreases depending on the presence or absence of the catalyst or the concentration of the concentration measuring substance, and the two show a proportional relationship. Becomes It should be noted that such a tendency becomes greater as the concentration of the reactant or product increases.

〔The invention's effect〕

As shown in the above action, the present measuring device exhibits a good proportional relationship, particularly linearity, over a wide concentration range of the measuring substance, which is extremely convenient for the measurement. The substance to be measured may be a reaction product or a product as long as it exhibits a predetermined proportional relationship. Further, unlike the color method and the like, continuous measurement can be performed, and it is more difficult to receive an electric nozzle than the electric method, so that stable measurement can be performed. Further, when an optical fiber is used, the process can be remotely controlled by extending the optical fiber, which is very useful.

〔Example〕

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

In this example, glucose concentration is measured using glucose oxidase as a catalyst in the following biochemical reaction system.

Glucose + O ₂ → Gluconolactone + H ₂ O ₂ A longitudinal sectional view of this measuring device is shown in FIG.

This device comprises a tubular body 1, a light emitting element 3, a light receiving element 4, and a test liquid supply device 5 for introducing a test liquid 6.

The tubular body 1 is a glass tube having an inner diameter of 3 mmφ, an outer diameter of 6 mmφ and a length of 120 mm. A test liquid introducing port 11 is attached to the end side surface near the one end of the tubular body 1, and a test liquid outlet port 12 is attached to the end side surface near the other end. The entire tube is covered with the light shielding box 7.

A light-emitting diode (LED) lamp is used as the light-emitting element 3, and a photodiode is used as the light-receiving element 4. Both are opposed to both end faces of the glass tube 1 and the amount of light transmitted from one end and received from the other end is taken as a current value It is configured to detect.

A test liquid supply device 5 for supplying the test liquid 6 is connected to the inlet 11 of the tubular body 1. Incidentally, 51
Is a metering pump and 52 is a filter.

This device was manufactured as follows. That is, first, the above glass tube was prepared, immersed in concentrated hydrochloric acid for 1 hour, and then
Silanization was carried out in 10% γ-aminopropylethoxysilane / acetone for 15 hours. Then, after air-drying for 1 hour, 5% glutaraldehyde / phosphate buffer solution (pH
7.0) for 4 hours.

This glass tube was immersed in 60 ml of 0.05M phosphate buffer (pH 7.0) in which 1 g of enzyme (glucose oxidase) was suspended,
Thereafter, the glass tube was taken out, the outer surface was wiped and dried to fix glucose oxidase 2 on the inner wall of the glass tube. Next, the LED 3 and the photodiode 4 were arranged so as to face both ends of the enzyme-immobilized glass tube, and the present measurement device was manufactured.

On the other hand, glucose was dissolved in 0.1 M phosphate buffer (pH 7.0) at various concentrations to obtain a test solution 6. When the enzyme-immobilized glass tube is desired to be stored, it is immersed in 0.05M phosphate buffer (pH 7.0).

Then, from one end of the inlet 11 of this device, various test liquids 6
Was continuously supplied so as to maintain a laminar flow state by driving the pump 51 of the test liquid supply device 5 at a flow rate of 1 ml / min. Next, the photocurrent when the test liquid 6 passes through the inside of the tubular body 1 was measured using the photodiode 4. The relationship between the glucose concentration and the photocurrent value which is the result is shown in FIG.

Next, as a comparative example, a test was conducted in the same manner as the above example except that the catalyst was not included, and the results are also shown in the same figure.

As shown in this figure, in the comparative example, even if the glucose concentration is increased, the gradient (change) in the relationship between the photocurrent value and the concentration is extremely small, so that sufficient sensitivity to that concentration cannot be obtained and its detection is not possible. Not suitable.

On the other hand, in the present embodiment, as a whole, the distribution shown in FIG. 3 (a) is shown, and as shown in FIG. 4 (a), the inner wall side has a larger refractive index than the center side of the tubular pair, Since the light is bent outward, the amount of transmission and absorption at the tube wall increased, and the amount of light received decreased as shown in FIG. Then, a good linear relationship with a large inclination was shown in a wide concentration range. The dotted straight line in FIG. 5 shows the case where 1% ammonium molybdate was dissolved in the test solution in advance and colored yellow with hydrogen peroxide generated on the wall surface of the glass tube. Both show almost the same results.

Therefore, by using this device, the concentration of glucose can be measured in a wide concentration range with good sensitivity and is useful as a biosensor. Further, continuous measurement can be performed at high speed without receiving electrical noise.

The present invention is not limited to the specific examples described above, and various modifications may be made within the scope of the present invention depending on the purpose and application. That is, the tubular body only needs to pass the test liquid, and various sizes, lengths, overall shapes, cross-sectional shapes, materials, etc. can be selected depending on the purpose and application. . For example, the entire shape may be a curved tube instead of a straight tube, and the cross-sectional shape thereof is usually a perfect circle, but it may be a square, a hexagon, an ellipse, etc., and a honeycomb shape or a lotus root shape. You may have several flow-path holes like this. When forming the coating layer, the film thickness, the porosity, the method for forming the same, etc. do not matter.
Further, on the light emitting side and the light receiving side, as shown in FIG. 4, an optical fiber 8 may be attached to the tubular body 1 via a rubber seal 13, or an optical fiber may be provided on one side of the tubular body 1. The element may be directly attached to the device. The length, thickness, material, form, mounting position, etc. of the optical fiber can be variously selected, and the material is not limited to glass, but may be resin.

Further, the light emitting element is not limited to the LED, and laser light such as argon can be used. As a light receiving element,
Other known ones can also be used.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a concentration measuring device according to an embodiment, and FIG. 2 is an explanatory diagram showing that a concentration (refractive index) distribution occurs in the radial direction of a tubular body of each reactant or product. I)
Shows substance A, (b) shows substance B, (c) shows substance C, and (d) shows substance D. FIG. 3 is an explanatory view showing that the refractive index distribution is generated in the radial direction of the tubular body as a whole. In FIG. 4, (a) shows a state where the inner wall side is large, and (b) shows a state where the center side is large. FIG. 4 is an explanatory view showing a locus of light passing through the tubular body, and FIG. It is a graph which shows the relationship with a value. 1; tubular body, 11; inlet, 12; outlet, 2; inner wall (or catalyst), 3; light emitting element, 4; light receiving element, 5; test liquid supply device, 6;
Test liquid, 7; light shielding box, 8; optical fiber.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideho Aoki 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Nihon Special Ceramics Co., Ltd. No. 18 Nihon Special Ceramics Co., Ltd. (72) Inventor Junichi Tokumoto 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Nihon Special Ceramics Co., Ltd.

Claims (1)

[Claims] 1. A catalyst for accelerating the reaction of a reactant contained in a test liquid is provided only on the inner wall, and the reaction produces a refractive index distribution in the radial direction of the tubular body as a whole of the reactant and the product. A tubular body having an inlet for introducing the test liquid and a lead-out port for leading out the test liquid, and directly or on one end side of the tubular body located on the inlet side or the outlet side. A light emitting element to be arranged via an optical fiber for light transmission, and to the other end side of the tubular body located on the outlet side or the inlet side, directly or via a light receiving optical fiber. An apparatus for measuring the concentration of a reaction product or a product in a test solution, comprising: a light receiving element.