JPH0612350B2 - Distribution type ion sensor body - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an ion sensor body for measuring an ion concentration in a sample solution to be measured.

[Technical background of the invention and its problems] Conventionally, an ion-selective electrode capable of selectively quantifying the concentration of a specific ion in a liquid has been used in a wide range of fields such as specific ion monitoring and water quality analysis. The ion-selective electrode uses that the potential difference ΔE generated between the potential generated from this electrode and the reference potential obtained from the reference electrode arranged in the same measurement system has a linear relationship with the logarithm of the concentration of the specific ion. Therefore, the ion concentration can be easily obtained from the value of ΔE measured from this. In recent years, in particular, quantification of various ions such as Na ⁺ , K ⁺ , C1 ^{− in} blood has been vigorously carried out using such an ion-selective electrode. Recently, ion-selective electrodes, which have no electrolyte solution inside and have an ion-sensitive membrane directly formed on a conductive member such as metal, have been used as the structure. Are installed side by side in the flow passage of
A flow cell type ion sensor body for measuring the concentrations of a plurality of types of ions has been devised. In recent years, the ion sensor body comprising such an ion-selective electrode and a reference electrode has been further miniaturized, and it has become possible to quantitatively analyze many kinds of ions with a small amount of the liquid to be measured.

However, even in such a miniaturized ion sensor body, a reference electrode for generating a reference potential is required in principle, but in the conventional reference electrode, in order to miniaturize and integrate with other ion selective electrodes, It had the following problems. That is, the structure of the conventional reference electrode is saturated with an internal electrolyte solution and a hole or liquid junction that is sized to allow a small amount of solution to flow in order to establish conduction between the internal electrolyte solution and the solution to be measured. Amakou electrode, an electrode obtained by immersing a silver / silver chloride electrode material in a saturated solution such as KCl, or a silver / silver chloride electrode material containing KCl-containing P
A reference electrode has been used which is covered with a VC film and then covered with a protective film such as a silicone polymer film. However, in the reference electrode composed of a structure having an internal electrolyte solution and a liquid junction, the internal electrolyte solution in the electrode is easily contaminated by the liquid to be measured due to the flow state of the liquid junction, and the internal size is small. Since only a small amount of the electrolyte solution entered, the life was short and the potential as the reference electrode was likely to fluctuate. And when creating a small-sized reference electrode having such a configuration, it is difficult to form a liquid junction or a structure for holding an internal electrolyte solution, and the liquid junction has a slight shape or size. It was difficult to obtain sufficient reliability as a reference electrode because the reference potential output by the output was greatly influenced.
On the other hand, in a reference electrode composed of a silver / silver chloride electrode material coated with a KCl-containing PCV curtain, KCl was eluted from the PCV film as the measurement was performed, and as a result, the reference potential as the reference electrode became unstable early. In addition, there is a problem that the life of the electrode is short.

Further, as a solution to the above problems, there is a flow-through type ion sensor body in which an ion-selective electrode for an item not directly related to measurement is provided and incorporated as a pseudo reference electrode. In the flow-through type ion sensor body, the ion selective electrode used as the pseudo reference electrode generally has an ion sensitive membrane having high impedance. Therefore, if the ion concentration is to be measured with the pseudo reference electrode as a reference, a normal ion-selective electrode also requires a high-impedance ion-sensitive membrane, so that noise may be mixed during actual ion concentration measurement. Occurs and this becomes a big problem. It is considered that this is because the ion concentration of the liquid to be measured is measured through the high-impedance ion-sensitive film, and it is difficult to carry out with the high-impedance ion-sensitive film.

[Object of the Invention] The present invention is intended to solve the above-mentioned drawbacks, and provides a flow-through type ion sensor body using a pseudo reference electrode and generating very little noise.

SUMMARY OF THE INVENTION The present invention covers a conductive member provided on at least a part of the inner surface of a through hole formed in a base made of an insulating material and a surface of a conductive member forming an inner peripheral surface of the through hole. A first ion-selective electrode, which is made of an ion-sensitive film and is sensitive to the substance to be measured contained in the liquid to be measured, and at least a part of the inner peripheral surface of the through hole formed in the base made of an insulating material. A second conductive member arranged so as to be formed and an ion-sensitive film covering the conductive member forming the inner peripheral surface of the through hole, which is not sensitive to the substance to be measured contained in the liquid to be measured. A reference electrode composed of an ion-selective electrode is connected while maintaining the electrical insulation of the conductive members, and the through holes of the first ion-selective electrode and the second ion-selective electrode are connected to form the target electrode. Integrated to form a flow path for the sample to be measured In the ion sensor body, the impedance is 200 KΩ or less, and more preferably 1 KΩ so as to come into contact with the sample to be measured in the flow path of the sample to be measured.
The flow-through type ion sensor body is characterized in that the following electrodes are provided.

By the way, in order to actually perform analysis using the flow-through type ion sensor body, for example, a measuring circuit as shown in FIG. 1 may be used. Na ^+, K + in Figure (1) is a flow type ion sensor of the present ^invention, C1 ^- potential difference from the measurement result of the potential difference between the sensor, but each ion concentration can be calculated, and direct reference electrode and the ion sensor The Ca ²⁺ ion-selective electrode, which is the reference electrode, has a high-impedance ion-selective membrane, and the Na ⁺ , K ⁺ sensors, etc., have a high-impedance ion-selective membrane. The arsenic measurement liquid is electrically connected to a measurement system including a preamplifier and the like via a high impedance film. as a result,
Since a large amount of noise will be mixed in, the low impedance electrode and the reference electrode, the low impedance electrode and the ion selective electrode of the low impedance electrode provided in the flow-through type ion sensor body of the present invention are used. The potential difference may be determined, and the difference between the potential differences between the two may be determined. By doing so, the liquid to be measured is grounded and noise is reduced.

In addition, (9) and (10) are operational amplifiers, respectively, and (11) is a potentiometer.

[Advantages of the Invention] The flow-through type ion sensor body according to the present invention can employ a measurement method in which the reference electrode can be ignored despite the high impedance. Further, since the electrode with low impedance can be easily incorporated, the industrial value of the present invention is great.

EXAMPLES OF THE INVENTION Hereinafter, the present invention will be described in more detail based on examples.

FIG. 2 shows a flow type ion sensor body as one embodiment of the present invention. In the figure, (4) is a sodium ion selective electrode,
(5) is a potassium ion selective electrode, (6) is a chloride ion selective electrode, (7) is a calcium ion selective electrode as a reference electrode, and each of these ion selective electrodes is an insulating member.
The cell body (1) a is disposed integrally and connected to the cell body (1) a while maintaining electrical insulation from each other by way of (3). And lead wires (4) a, (5) a for extracting signals to each electrode,
(6) a and (7) a are connected, respectively. This electrode is provided with an ion sensitive part (10) on the inner peripheral surface of a through hole formed in a base made of an insulating material, and the through hole of these electrodes communicate with each other to form a flow passage (2). ing. Further, the ion sensitive part (10) of these electrodes is composed of an ion sensitive film covering a conductive member arranged so as to form at least a part of the inner peripheral surface of the through hole. The film comprises, for example, a polymer film in which an ion-selective substance is dispersed or a sensitive layer made of silver chloride formed on silver used as a conductive member. Further, (8) is a low-impedance platinum electrode provided characteristically in the flow-through type ion sensor body of the present invention, and (8) a is a lead wire from the platinum electrode.

FIG. 3 shows the actual use of the flow-through type ion sensor body of the present invention.
The case where the tracking potential of Na ⁺ sensor shown by curve (a), a curve in the case of tracking the potential of Na ⁺ sensor using a conventional flow type ion sensor body (b) in the measurement potential Yes and manifested The difference in changes is significant. As is clear from the figure, it was found that the noise was visibly reduced when the measurement method in which the liquid earth was used was adopted using the flow-through type ion sensor body of the present invention. Was able to be fully achieved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an ion concentration measuring circuit used in the flow-through type ion sensor body of the present invention. FIG. 2 is a sectional view of the fluid type ion sensor body of the present invention. FIG. 3 is an explanatory view for explaining the noise generation state of the circulating ion sensor body of the present invention and a known sensor body. (4), (5), (6), (7) …… ion selective electrode (8) …… platinum electrode

Claims (1)

[Claims] 1. A conductive member arranged to form at least a part of an inner peripheral surface of a through hole basically formed of an insulating material, and a conductive member forming an inner peripheral surface of the previous through hole. A first ion-selective electrode, which is composed of an ion-sensitive film covering the surface and is sensitive to the substance to be measured contained in the liquid to be measured, and an inner peripheral surface of the through hole formed in the substrate made of an insulating material. It is comprised of a conductive member arranged so as to form at least a part, and an ion-sensitive film having a film resistance of 10 KΩ or more that covers the surface of the conductive member forming the inner peripheral surface of the through hole A reference electrode composed of a second ion-selective electrode that is insensitive to the measured substance to be measured, and is electrically connected to each other while maintaining electrical insulation, and the first ion-selective electrode and the second ion-selective electrode The sample to be measured, in which the through-holes of the conductive electrode are connected An ion sensor body integrated so as to form a flow passage, further comprising an electrode having an impedance of 200 KΩ or less so as to come into contact with the measurement sample in the flow passage of the measurement sample. A flow-through type ion sensor body characterized in that