JP3248787B2 - Concentration measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concentration measuring device,
In particular, the present invention relates to a concentration measuring device suitable for use in fields such as the chemical industry, food industry, medical care, and environmental measurement.

[0002]

2. Description of the Related Art Conventionally, this type of concentration measuring device has
For example, a temperature change detection type concentration measuring device is known.
As shown in FIG. 10, the concentration measuring apparatus supplies a liquid to be inspected through a supply pipe 2 into a constant temperature bath 1 kept at a constant temperature, and after the temperature is made constant by a heat exchanger 3, the liquid to be inspected is Is reacted with a predetermined reactor 4, a rise in liquid temperature due to heat generated by the reaction is detected by a temperature sensor 5 such as a thermistor, and the concentration of the test liquid is obtained from the value of the rise in temperature. Further, as a simpler method, there is a method in which a concentration detection element is directly immersed in a test liquid to determine the concentration of the test liquid.

[0003]

However, in the case of the above-mentioned temperature change detection type device, it is necessary to provide a heat exchanger or mount a temperature sensor on the reactor, so that the structure of the device becomes complicated. Since it is necessary to house a heat exchanger, a reactor, and the like in a constant temperature bath, there is a problem that the apparatus is inevitably increased in size, complicated in handling, and lacking in portability. In addition, the use of electric means for heating the thermostatic bath causes a problem that the temperature sensor is susceptible to electromagnetic interference, and the stability and reliability of the measurement are lacking. The latter method has the advantage that the configuration is very simple and easy to use, but has the problem that the measurement result is greatly affected by the surrounding environmental conditions and the measurement error increases. SUMMARY OF THE INVENTION The present invention is directed to solving the above-described problems, and has a small and simple configuration and is capable of performing an accurate and reliable measurement without being adversely affected by external temperature or electromagnetic induction. It is an object to provide a measuring device.

[0004]

In order to achieve the above-mentioned object, a structural feature of the invention according to the first aspect is that a cell portion having a hollow portion provided with a test liquid supply port and a core are provided. An exposed portion of the core formed on at least a portion of the optical fiber cable covered by the cladding layer is covered with a hollow covering, and a core having a refractive index between a predetermined intrinsic temperature around the hollow covering and the exposed portion of the core. A medium that changes from a value larger than the refractive index of the optical fiber cable to a smaller value is enclosed, and a constant temperature heating means provided in the cavity, a light incident means provided on one end side of the optical fiber cable, and a medium provided in the cavity. There is provided at least one concentration detecting element provided, and measuring means for processing the output from the concentration detecting element to determine the characteristics of the test liquid supplied into the cavity.

[0005]

According to the first aspect of the present invention, the test liquid is introduced from the test liquid supply port into the cavity provided with the constant temperature heating means, and then the light incident means is used. When light enters the optical fiber cable of the constant temperature heating means, when the temperature of the test liquid is lower than the intrinsic temperature of the medium, the refractive index of the medium is larger than the refractive index of the core, so that much of the incident light passes through the medium. The test liquid in the cell section is heated to raise the liquid temperature. Then, when the liquid temperature becomes higher than the specific temperature of the constant temperature heating means, the refractive index of the medium is smaller than the refractive index of the core, so that the incident light does not pass through the medium, and the heating of the liquid to be inspected in the cell portion is stopped. In this way,
The cell portion is maintained at a constant temperature by the constant temperature heating means, and the test liquid flowing into the cavity is also maintained at a constant temperature. Here, the liquid to be inspected is in direct contact with the constant temperature heating means, and the gap of the cavity can be narrowed, and the amount of the liquid to be supplied to the cavity can be reduced. The liquid is immediately heated to a constant temperature by the constant temperature heating means. And
The concentration of the predetermined component of the test liquid maintained at a constant temperature is detected by the concentration detecting element, and the output thereof is measured by the measuring means to determine the concentration of the predetermined component of the test liquid.

As described above, according to the first aspect of the present invention, the temperature of the test liquid supplied into the cavity is rapidly increased, so that the measurement time is remarkably reduced and the working efficiency is improved. Stable measurement can always be performed under constant conditions without being affected by changes in the surrounding temperature. In addition, the amount of the test liquid can be reduced by reducing the test liquid storage space. In addition, since this concentration measuring device does not require a thermostatic bath or the like for keeping the liquid to be inspected warm, it is very compact, easy to handle and move, and excellent in practicality and versatility. I have. Furthermore, this concentration measuring device employs optical means for heating the liquid to be inspected and does not affect the concentration detecting element due to electromagnetic induction disturbance, so that the reliability of the measurement is assured and the sensitivity is high. Accurate concentration measurement results can be obtained.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a concentration measuring device according to a first embodiment of the present invention. The concentration measuring device has a cylindrical acrylic resin cell portion 10 (inner diameter 3).
mmφ × 10 mmφ outside diameter × 35 mm length). However, a vinyl chloride resin or the like may be used instead of the acrylic resin. A constant temperature heater 20 as a constant temperature heating means is provided in the cylindrical hollow portion K provided at the axial position of the cell portion 10.

As shown in FIG. 2, the thermostat 20 is provided on a part of the optical fiber cable P1. The outer coat material 23 is peeled off over 30 mm, and the clad material 22 is peeled off by 25 mm. The core 21 is exposed. The exposed portion of the optical fiber cable P1 where the core 21 and the clad material 22 are exposed is a cylindrical aluminum tube 2 filled with an oleyl alcohol solution 25 as a medium.
4 (Inner diameter 1.5mmφ × Outer diameter 2.0mmφ × Length 27m
ml). Aluminum tube 24
Are O-rings 26a inserted at the tip of the clad material 22,
The cable is supported by a cable 26b, and both ends are caulked to the optical fiber cable P1 near the tip of the clad material 22 and sealed by silicon rubbers 27a and 27b. The aluminum tube 24 is provided on its inner wall surface with a film coated with ink and dried to absorb light efficiently. As shown in FIG. 1, the incubator 20 has a left end liquid-tightly inserted into a stopper 10 b fixed to a left end of the cylindrical cavity K, and a right end having a rubber at a right end of the cylindrical cavity K. It is fixed to the cell part 10 by inserting the stopper 10a. The thermostat may be formed at the end of the optical fiber cable and reflect light at the end. The other end of the optical fiber cable P1 is connected to a light source 30 composed of a laser diode device having an output of 30 mw, which is a light incident means. However, the light source is not limited to the laser diode device, and a light source having similar output characteristics can be used.

At a position near the right end of the cell section 10, as shown in FIG. 1, a test liquid supply hole 11a penetrating the tube wall and reaching the cylindrical cavity K is provided. A test liquid supply pipe 11 for supplying the test liquid is attached. At the position near the left end of the cell section 10, as shown in FIG. 1, there is provided a test liquid discharge hole 12a which penetrates through the pipe wall and reaches the cylindrical hollow portion K.
A test liquid discharge pipe 12 for discharging the test liquid is attached to the test liquid. A test liquid container (not shown) is attached to the other end of the test liquid supply pipe 12, and a discharge pump (not shown) is mounted to the other end of the test liquid discharge pipe 13. Have been.

Three mounting holes 13a, 14a and 15a are provided at the left and right central portions of the cell portion 10 so as to penetrate the tube wall and reach the cylindrical hollow portion K. In these three mounting holes, a sodium ion electrode 13, a potassium ion electrode 14, and a reference electrode 15 are disposed in a liquid-tight manner such that the sensitive portion at the tip thereof is in contact with the cylindrical cavity K. Each of the electrodes 13, 14, 15 is connected to the electrometer 16 by a lead wire.

The operation of the embodiment configured as described above will be described. First, a serum liquid is injected into the cylindrical cavity K from the test liquid supply pipe 11. Since the thermostat 20 is inserted into the cylindrical cavity K and the space is configured to be very narrow, the amount of the test liquid to be injected can be reduced. Next, by turning on a power switch (not shown), the light source 30 is driven, and the laser light is incident on the thermostat 20 through the optical fiber cable P. At this time, the liquid temperature is in the range of 21 to 23 ° C.
The oleyl alcohol liquid 25 in the inside has a refractive index larger than the refractive index of the core 21 at 30 ° C. or lower, and matches the refractive index of the core 21 at about 30 ° C., so that the temperature of the thermostat 20 becomes 30 ° C. Part of the permeate penetrates into the oleyl alcohol solution 25 from the core and is absorbed by the aluminum tube 24 to keep it heated.

When the temperature of the thermostat 20 rises to 30 ° C. or higher, the refractive index of the oleyl alcohol liquid 25 increases.
, The transmission of light from the core 21 to the oleyl alcohol liquid 25 is stopped, and the heating of the thermostat 20 is stopped. By repeating such an operation, the thermostat 20 is heated to 30 ° C.
Maintained near. At this time, when the temperature of the thermostat 20 reaches 30 ° C., the test liquid injected into the cylindrical cavity K is directly heated by the thermostat 20 and the cylindrical cavity K is heated.
Since the amount of liquid to be inspected is small,
Heated to ° C and always maintained at 30 ° C.

By measuring the sodium ion and potassium ion concentrations of the test liquid using the sodium ion electrode 13, the potassium ion electrode 14, and the reference electrode 15, a measurement result can be obtained in a short time. And, when the sodium ion concentration is 0.1, 1, 10, 10
The output voltage value at 0,1000 mmol / l is shown in FIG.
It is clear that the logarithmic value of the concentration is proportional to the output voltage when the concentration is 1 mmol / l or more, as shown in FIG. Further, when the potassium ion concentration is 0.1, 1, 10, 100 mmol /
As shown in FIG. 4, the output voltage value at 1
It is clear that the logarithmic value of the concentration is proportional to the output voltage above mol / l. As a result, when the concentration of the test liquid containing both ions is 1 mmol / l or more, an accurate ion concentration can be obtained by the above measurement using FIGS. In this measurement, the ambient temperature was 10, 15,
Table 1 below shows the measurement results at 20, 25, and 30 ° C.

[0014]

[Table 1]

From the above results, the measurement error due to the ambient temperature of the concentration measuring device was about 2%, and a very accurate result was obtained.

As described above, in the above-mentioned concentration measuring apparatus, the test liquid supplied into the narrow cavity is directly heated by the thermostat and the amount of the liquid is small. The work efficiency can be significantly shortened and the working efficiency can be increased, and stable measurement can always be performed under constant conditions without being affected by changes in the surrounding temperature. Further, the amount of the test liquid can be reduced by narrowing the cavity. In addition, since this concentration measuring device does not require a constant temperature bath or the like for keeping the liquid to be inspected, it is very compact, and has practicality and versatility such as easy handling and convenient movement. Has been enhanced. Furthermore, since optical means is used to keep the test liquid warm,
Since the concentration detecting element is not affected by the electromagnetic interference, the reliability of the measurement is guaranteed, and a highly sensitive and accurate concentration measurement result can be obtained. In addition, the measuring device can easily process the measurement result electrically, and thus can perform automatic measurement.

Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 shows a schematic configuration of a concentration measuring device according to a second embodiment. This concentration measuring device is a cylindrical acrylic resin cell unit mounted on a table 40 also serving as a signal amplifier. 50. However, a vinyl chloride resin or the like may be used instead of the acrylic resin.
In a cylindrical hollow portion K at the center of the cell portion 50, a thermostat 60 as a constant temperature heating means is provided.

As shown in FIGS. 5 and 7, the cell section 50 includes a cylindrical element holding section 51 and a container 52 for accommodating the element holding section 51. The element holding portion 51 has a through hole 51a at the center line of the cylindrical shape. As shown in FIG. 8, a liquid injection port 51b cut in a conical shape is provided around the through hole 51a on the upper surface of the cylinder, and a conical notch is formed around the through hole 51a on the lower surface of the cylinder. A space 51c is provided. The space 51c is provided with the liquid inlet 5
It is provided to keep the test liquid injected from 1b at the through hole 51a. Accordingly, it is possible to prevent the test liquid from entering the gap between the holding unit 51 and the container 52 to stain the cell unit 50 and adversely affect the subsequent measurement.
In the vertical middle position of the cylindrical side surface of the element holding portion 51, 3
The element insertion holes 51d1 to 51d3 are provided so as to penetrate in the radial direction to reach the through holes 51a, and the element insertion holes 51d are provided at intervals of a central angle of 120 ° with respect to the through holes 51a. . Further, three mounting grooves 51e1 to 51e are formed on the cylindrical side surface of the element holding portion 51 in parallel with the center line.
e3 are provided, and each of the mounting grooves 51e1 to 51e is provided.
3 are provided at a center angle of 120 ° with respect to the center.

The container 52 is, as shown in FIGS. 7 and 9, a cylindrical container provided with a bottom plate 52a.
A constant temperature chamber insertion hole 52a1 is provided at the center of a.
On the inner side surface of the container 52, three guide rails 52 b 1 to 52 b 3 are provided at positions corresponding to the mounting grooves 51 e 1 to 51 e 3 of the element holding part 51. In addition, container 5
Two electrode terminals 52c1 to 52c3 are provided at positions corresponding to the element insertion holes 51e1 to 51e3 of the element holding portion 51 from the upper surface to the inner side surface of the device holder 2. Electrode terminal 52c
1 to 52c3 are fixed to the container 52 by penetrating and attaching the fixing rods 52d1 to 52d3 from the upper surface to the lower surface of the side wall.

The thermostat 60 has a structure using substantially the same optical fiber as the thermostat shown in the first embodiment. As shown in FIG. 6, about 18 mm from one end of the optical fiber cable P2.
The coating material 62 and the clad material are peeled off over the entire surface, and a reflection film 63 is provided on a cross section of the exposed end of the core 61. The exposed portion of the core 61 has an aluminum tube 64 (1.0 mmφ in diameter × 1.
5 mmφ × 20 mm length). The aluminum tube 64 has an inside filled with oleyl alcohol 65 as a medium, and is fixed to the optical fiber cable P2 by caulking the coating material 62 at the tip.
The inner surface of the aluminum tube 64 is provided with an anti-reflection film (not shown) formed by applying and drying ink to prevent reflection of light. The contact portion between the aluminum tube 64 and the coating material 62 is sealed by a silicone rubber 66. In addition, the thermostat is not limited to the reflection type, and may be a type provided at an intermediate portion of the optical fiber cable P1, as shown in FIG. A socket 67 is attached to the other end of the optical fiber cable P2,
The optical fiber cable P2 is connected by a socket 67 to a light source 70 comprising a laser diode device having an output of 30 mw, which is a light incident means. However, the light source is not limited to the laser diode device, and a light source having similar output characteristics can be used. The amplifier 41 provided in the table 40 is a preamplifier that amplifies a small signal from the density detecting element to a level not affected by noise or the like. This preamplifier is connected to the electrometer 80 by a cable L.

Next, the assembly of the above-mentioned concentration measuring device will be described. First, the container 52 is fixed to the base 40, and the fixing rods 52 of the electrode terminals 52c1 to 52c3 of the container 52 are fixed.
The lower ends of d1 to 52d3 are connected to the amplifier 41 provided inside the table 40 by lead wires. Next, the sodium ion electrode 13, the potassium ion electrode 14, and the reference electrode 15 are attached to the element insertion holes 51d1 to 51d3 of the element holding part 51 in a liquid-tight manner so that the sensitive part at the tip thereof is in contact with the cylindrical cavity K. . The element holding portion 51 is attached to the mounting groove 51
e1 to 51e3 are used as guide rails 52b1 to
Attach to the container 52 in accordance with 52b3. And
The lead wires of the electrodes 13, 14, and 15 are fixed to the electrode terminals 52 c 1 to 52 c 3 of the container 52 using fixing rods 52 d 1 to 52 d 3. Next, the thermostat 60 is passed from below the table 40 and the insertion hole 5 formed in the bottom wall 52a of the container 52 is inserted.
2a1, a through hole 51a at the center of the element holding portion 51
And fixed liquid-tight to the bottom wall 52a.

The operation of the embodiment configured as described above will be described. First, a serum solution (a Na ion concentration of 114.3 mM,
(K ion concentration: 2.92 mM) was added dropwise. Then, when the power switch (not shown) is turned on, the light source 70 is driven, and the laser light is incident on the thermostat 60 through the optical fiber cable P2. At this time, the room temperature is in the range of 21 to 23 ° C.
By the same operation as described in the embodiment, the incubator is maintained at 30 ° C., and the serum is immediately maintained at about 30 ° C. By measuring the serum solution kept at this constant temperature, the first
Similar to the results shown in the examples, uniform measurement results not affected by the ambient temperature were obtained.

As described above, in the concentration measuring apparatus according to the second embodiment, the effects shown in the first embodiment can be obtained, and the cell portion can be further downsized. The amount of the test liquid can be further reduced, and the liquid temperature can be set to a constant value in a shorter time, so that the measurement time can be further reduced.
The incubator 30 is not limited to the reflection type shown in FIG. 6, but may be provided at an intermediate portion of the optical fiber cable without sealing the tip as shown in FIG.

In each of the above embodiments, quartz glass is used as the core material of the optical fiber cable. However, other optical glass and plastic materials such as polystyrene, polymethyl methacrylate, and silicone rubber can be used. . In this embodiment, oleyl alcohol is used as the medium, but many other types of media can be freely selected and used. Thus, an appropriate medium can be selected in accordance with the measurement application from the temperature range, heat resistance, measurement sensitivity, and the like, so that the degree of freedom in designing the thermostat is increased and the range of application can be expanded. The medium is not limited to a single medium, and may be a solution (for example, a colloid solution or the like) obtained by mixing two or more types of liquids or a liquid and a solid. Further, the medium is not limited to a liquid, and may be a solid obtained by coagulating a liquid. Further, in each of the above embodiments, an ion electrode is used as the concentration detecting element, but various sensors such as a pH electrode, a biosensor, and a glucose concentration sensor can be used according to the liquid to be measured and the purpose of measurement.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing a schematic configuration of a concentration measuring device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a thermostat of the concentration measuring device.

FIG. 3 is a graph showing a relationship between a sodium ion concentration measured by the concentration measuring device and a measured output voltage.

FIG. 4 is a graph showing a relationship between a potassium ion concentration measured by the concentration measuring device and a measured output voltage.

FIG. 5 is a partially broken front view showing a schematic configuration of a concentration measuring device according to a second embodiment.

FIG. 6 is a schematic sectional view showing the thermostat of the embodiment.

FIG. 7 is an exploded perspective view showing the cell unit.

FIG. 8 is a sectional view taken along line MM and a plan view showing an element holding portion of the cell portion.

FIG. 9 is an NN sectional view and a plan view showing a container of the cell part.

FIG. 10 is a partially broken sectional view showing a main part of a concentration measuring device according to a conventional example.

[Explanation of symbols]

10, 50; cell part, 11; test liquid supply pipe, 11a;
Test liquid supply port, 12; Test liquid discharge pipe, 12a; Test liquid discharge port, 13; Sodium ion electrode, 14; Potassium ion electrode, 15; Reference electrode, 16, 80; Electrometer, 200, 60; Thermostat, 21, 61; core, 22; clad material, 23, 62; coat material, 2
4, 64; aluminum tube, 25, 65; oleyl alcohol, 27a, 27b, 66; silicon rubber, 30,
70; light source (laser diode device); 63; reflective film;
67; socket, P1 to P2; optical fiber cable.

Claims (1)

(57) [Claims] 1. A cell having a cavity provided with a liquid supply port to be inspected, and an exposed portion of the core formed on at least a part of an optical fiber cable having a core covered by a cladding layer, with a hollow covering. A medium whose refractive index changes from a value larger than the refractive index of the core to a value smaller than the refractive index of the core is sealed between the hollow coated body and the exposed portion of the core between the hollow coated body and the exposed portion of the core. Constant temperature heating means, light incident means provided on one end side of the optical fiber cable, at least one concentration detection element provided in the cavity, and processing an output from the concentration detection element. And a measuring means for determining characteristics of the test liquid supplied into the cavity by the method.