JPH0812151B2 - Hydrogen peroxide concentration measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydrogen peroxide concentration measuring device, and more specifically, it is capable of continuous measurement, less susceptible to electrical noise, and excellent in a wide concentration range. The present invention relates to a hydrogen peroxide concentration measuring device capable of measuring and further remotely controlling a process as needed.

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]

A conventional hydrogen peroxide concentration measuring device has a predetermined electrode liquid filled inside, a cathode, an anode, and a resin film (Teflon film or the like) arranged on the surface of this cathode and through which oxygen (hydrogen peroxide) can pass. It is known that it consists of an oxygen electrode (hydrogen peroxide electrode) ("Biosensing", P.42, edited by Seio Karube, published by Keigaku Shuppan Co., Ltd.).
In this method, the concentration of hydrogen peroxide is detected by measuring the current or potential generated by the decomposition reaction of hydrogen peroxide on the cathode (platinum electrode plate).

Further, as a hydrogen peroxide concentration analyzer using light, there is also known a device for measuring the concentration from the absorbance at a specific wavelength by adding a dye that is oxidized by hydrogen peroxide to develop a color.

[Problems to be Solved by the Invention]

The above conventional one using electricity is easily affected by noise and the analysis speed is not sufficiently fast. The above-mentioned device utilizing light is difficult to perform continuous measurement because the color development reaction is irreversible, and since this dye is an organic substance, it also has a problem in terms of long life and stability.

The present invention has been made in view of the above viewpoints, in which a predetermined oxide or the like accelerates the decomposition of hydrogen peroxide, and further decomposes the hydrogen peroxide in the tubular body using the decomposition promoting substance. To produce a concentration gradient of hydrogen peroxide in the radial direction, thereby changing the propagation characteristics of light,
It was completed by finding out.

It is an object of the present invention to provide a hydrogen peroxide concentration measuring device capable of continuous measurement, having a high analysis speed, being less susceptible to electrical noise, and being capable of excellent measurement in a wide concentration range.

[Means for solving the problem]

The apparatus for measuring hydrogen peroxide concentration of the present invention is characterized by comprising a tubular body, a light emitting element and a light receiving element, wherein the tubular body has a hydrogen peroxide decomposition promoting substance at least on the inner wall thereof, An inlet for introducing the test liquid for measurement and an outlet for leading out the liquid to be measured are provided, and the light-emitting element is directly on one end side of the tubular body located on the inlet side or the outlet side. Alternatively, the light receiving element is arranged via the light transmitting optical fiber, and the light receiving element is arranged on the other end side of the tubular body positioned on the outlet side or the inlet side, directly or via the light receiving optical fiber. To be done.

The above-mentioned tubular body may have at least an inner wall having a hydrogen peroxide decomposition accelerating substance, and may be produced by firing the tubular body only with this hydrogen peroxide accelerating substance or mainly with this substance. It is also possible to form a tubular body not containing a promoting substance and form a coating film on the inner wall of the tubular body using only the promoting substance or a composition mainly containing the promoting substance.

As the hydrogen peroxide decomposition accelerating substance, CuO, Cu ₂ O, P
_{b 3 O 4, PbO, PbO} 2, FeO, can be used _{Mn 3 O 4, MnO 2,} V 2 O 5 and at least one of the hydrogen peroxide degrading enzyme. When the coating layer is formed, it may be formed on a predetermined portion of the tubular body. Usually, the entire inner wall surface is coated, but it may be a part thereof.

[Action]

While the test liquid passes through the inside of the tubular body, the decomposition reaction of hydrogen peroxide occurs due to the interface between the inner wall and the liquid. Therefore the second
As shown in FIG. 3A, a concentration distribution of hydrogen peroxide is generated in the radial direction from the central axis of the tubular body, so that a refractive index distribution is generated accordingly. Incidentally, in the case where a tubular body having no decomposition promoting substance is used and the concentration distribution does not occur because hydrogen peroxide does not decompose, FIG.
Shown in The gradient of this distribution increases as the concentration of hydrogen peroxide in the test liquid increases.

The light 8 incident on the test liquid from the optical fiber 2 has its incident angle (θ) on the wall reduced due to the gradient of the refractive index of the liquid as shown in FIG. And the number of reflections decreases, and in the figure, 9 indicates light having no refractive index gradient. Therefore, in the case of the present invention, stronger light will reach the light receiving element than in the case where hydrogen peroxide is not present and in the case where the decomposition promoting substance is not present on the inner wall and the concentration distribution is not generated. The amount of received light increases as the concentration of hydrogen peroxide increases, and the two show a proportional relationship.

〔The invention's effect〕

As shown in the above operation, the present measuring device exhibits a good proportional relationship, particularly linearity, over a wide range of hydrogen peroxide concentration, which is extremely convenient for the measurement. Further, compared to the electrical method, electrical noise is less likely to be received, and therefore stable measurement can be performed, and continuous measurement can be performed unlike the dye method. 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.

Typical of the above hydrogen peroxide decomposition promoting substances, copper oxide Cu
Using O, a measuring device was manufactured to measure the relationship between hydrogen peroxide concentration and photocurrent. A vertical cross-sectional view of the measuring device is shown in FIG.

This apparatus comprises a tubular body 1, a light-sending optical fiber 2, a light-receiving optical fiber 3, a light-emitting element 4, a light-receiving element 5, and a test liquid supply device 6 for introducing a test liquid 7.

This tubular body 1 has an inner diameter of 3 mmφ, an outer diameter of 6 mmφ, and a length of 120 mm.
And is composed of copper oxide CuO. Then, one end of the optical fiber 2 for light transmission is inserted into one end of the tubular body 1 via a rubber seal 13, and the test liquid introducing port 11 is attached to the end side surface near this end. Further, one end of the light receiving optical fiber 3 is inserted into the other end of the tubular body 1 via a rubber seal 14, and the test liquid outlet 12 is provided on the end side surface near this end.
Is installed. The optical fibers 2 and 3 may be attached in reverse. The rubber seal portions 13 and 14 may be an integrated body (an integrally molded body or a joined body) with other body portions, and the material thereof does not matter.

Both optical fibers 2 and 3 have a length of about 1,000 mm, and their material is glass. A light emitting diode (LED) lamp is used as the light emitting element 4, and is arranged at the other end of the light transmitting optical fiber 2. As the light receiving element 5, a photodiode is used and is arranged so as to face the other end of the light receiving optical fiber 3, and the amount of light received from this other end is detected as a current value.

A test liquid supply device 6 for supplying the test liquid 7 is connected to the inlet 11 of the tubular body 1 via a pump.

The tubular body 1 was manufactured as follows. That is, 300 g of copper oxide (CuO reagent, particle size 1.5 μm) and 200 g of deionized water
Along with 500 g of 15 mmφ alumina spheres, they were placed in an alumina pot having an internal volume of 1 and pulverized at 84 rpm for 24 hours. Then add 3 g of polyvinyl alcohol and mix for an additional 24 hours. Thus, the sludge was produced, and this sludge was freeze-dried and passed through a 60-mesh sieve to produce a predetermined powder.

This powder was molded by a rubber press molding method at a pressure of 1000 kg / cm ²
The above-mentioned tubular body 1 was manufactured by molding the above-mentioned tubular body under the conditions described above and then firing at 1000 ° C. for 1 hour in the atmosphere.

The optical fibers 2 and 3 were attached to both ends of the tubular body 1 and almost in the center thereof, and the LED 4 and the photodiode 5 were attached to predetermined positions to manufacture the present measuring device. Then, the test liquid 7 having various hydrogen peroxide concentrations was supplied from one end of the introduction port 11 of this device by driving the pump of the test liquid supply device 6 at a flow rate of 1 ml / min. Then
The photocurrent when the test liquid 7 passes through the inside of the tubular body 1 was measured using the photodiode. The relationship between the hydrogen peroxide concentration and the photocurrent value, which is the result of this, is shown in FIG.

Then, a comparative example having no hydrogen peroxide decomposition promoting substance was carried out as follows. That is, a test was performed in the same manner as above using a glass tube (Comparative Example 1) and an alumina porcelain tube (Comparative Example 2) having the same shape as the above. Although the copper oxide was black, the glass tube and the alumina porcelain tube were translucent, so in order to approximate the measurement conditions of the example and the comparative example, in this comparative example the entire tube was a light shielding box. Covered. This result is also the fourth
As shown in the figure.

As shown in this figure, in both Comparative Examples 1 and 2, even if the concentration was increased, the absolute value of the photocurrent value was small and the gradient (change) in the relationship between it and the hydrogen peroxide concentration was extremely small. It is not suitable for its detection because sufficient sensitivity cannot be obtained.

On the other hand, in this example, a good linear relationship with a large inclination was shown in a wide concentration range. Therefore, by using this device, it is possible to measure the concentration of hydrogen peroxide satisfactorily and with high sensitivity in a wide concentration range. Further, by further extending the optical fiber, remote control of the process can be facilitated, and continuous measurement can be performed at high speed without receiving electrical noise. Other oxides (Cu ₂ O, Pb
O, PbO _2, FeO, even with Mn ₃ O _4, MnO ₂ or V ₂ O _5), showed good results in the same manner as described above.

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, or the like, or a honeycomb shape or a lotus root shape. You may have several flow-path holes like this. If it is composed of a decomposition accelerating substance and other materials, 50%
It is preferably contained in an amount of not less than wt%. When forming the coating layer, the film thickness, the porosity, the method for forming the same, etc. do not matter. In this case, the material of the main body is usually ceramic, but is not limited to this.

Further, instead of using the optical fiber on the light emitting side and the light receiving side, the light emitting element and the light receiving element may be directly attached to the tubular body, or the optical fiber may be configured on one side and the element may be directly attached on the other side. It may be attached. The length, thickness, material, form, attachment position, etc. of the optical fiber can be variously selected. For example, the material is not limited to glass and may be resin.

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

This device directly detects the hydrogen peroxide concentration, and can also be used for those that can measure the concentrations of other substances by detecting the hydrogen peroxide concentration. For example, the glucose concentration can be measured by providing a glucose oxidase-immobilized cell in the preceding stage, and therefore the present device can also be applied as a biosensor.

As a reference example, similar to hydrogen peroxide, it is also applied to the measurement of substances that decompose by catalysts and generate substances (oxygen, nitrogen, chlorine, carbon dioxide, etc.) that are easy to diffuse or volatilize and reduce the concentration of dissolved substances. it can. In this case, it is the same as in the present invention that the catalytic substance that promotes the decomposition of this substance is held on the inner wall of the tubular body. For example, such substances include ammonium nitrate (NH ₄ NO ₃ ) or ammonium nitrite (NH ₄ NO ₂ ).

[Brief description of drawings]

FIG. 1 is an explanatory sectional view of a hydrogen peroxide concentration measuring apparatus according to an embodiment, FIG. 2 is an explanatory view showing that concentration (refractive index) distribution occurs in the radial direction of the tubular body, and FIG. 3 is a tubular body. And FIG. 4 is a graph showing the relationship between the hydrogen peroxide concentration and the photocurrent value in the example. 1; tubular body, 11; inlet, 12; outlet, 13; inner wall, 2; light emitting side optical fiber, 3; light receiving side optical fiber, 4; light emitting element, 5;
Light receiving element, 6; Test liquid supply device, 7; Test liquid.

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

Claims (1)

[Claims] 1. A tubular body having a hydrogen peroxide decomposition accelerating substance on at least a meat wall, and having an inlet for introducing a test liquid for measuring hydrogen peroxide concentration and an outlet for discharging the test liquid. A light-emitting element disposed on one end side of the tubular body located on the inlet side or the outlet side, directly or via an optical fiber for light transmission, and located on the outlet side or the inlet side. A hydrogen peroxide concentration measuring device, comprising: a light receiving element disposed on the other end side of the tubular body, directly or through an optical fiber for receiving light.