JPH067113B2 - Ion concentration analyzer - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an ion concentration analyzer including an ion-selective electrode and a reference electrode in a flow path of a test liquid, and more specifically, to stabilize the reference electrode for a long term. Moreover, the present invention relates to an ion concentration analyzer that can be used without maintenance.

[Technical background of the invention and its problems] An ion-selective electrode has the feature that it can selectively quantify the concentration of a specific ion in a liquid, and has been used in a wide range of fields such as monitoring specific ions and water quality analysis. ing.

This is because there is a linear relationship between the potential indicated by the ion-selective electrode and the logarithm of the concentration of the target specific ion, and the target ion concentration can be easily calculated from the measured potential. In recent years, such ion-selective electrodes have been used for medical purposes, in particular, for quantifying various ions such as Na ⁺ , K ⁺ , Cl ⁻ existing in blood. Also, various types of analyzers using ion-selective electrodes have been manufactured.

By the way, in the measurement method using such an ion-selective electrode, when measuring the ion concentration in the test liquid, a reference electrode that generates a reference potential is required in addition to the ion-selective electrode. . Such a reference electrode is configured to electrically connect the internal liquid contained therein to the test liquid through the liquid junction.

FIG. 3 shows an example of a reference electrode widely used conventionally. In FIG. 3, (1) is the internal reference electrode, (2) is the internal liquid, and (3) is the liquid junction. Since the internal liquid (2) is diffused to the outside through the liquid junction (3) and consumed, the internal liquid is additionally used from the replenishment port (4) at appropriate times. Such a conventional reference electrode liquid junction (3) uses a plug or pinhole for diffusing the internal liquid (3) such as glass fiber or ceramic porous body little by little to maintain electrical continuity. However, the test liquid containing a large amount of proteins and organic components such as blood and urine has a drawback that it does not function properly due to contamination of the liquid junction and clogging due to attachment of the test liquid component. In order to prevent such accidents such as clogging of the liquid junction, an analyzer having the configuration example shown in FIG. 4 has been manufactured. In Fig. 4, the liquid junction (3) is completely held by a three-way cock etc. and there is no problem of clogging, but a large amount of internal liquid (2) is always provided in the internal liquid tank (5) and the pump (6) Therefore, it is wasteful that the reference electrode tank (7) having the internal reference electrode (1) must be replenished from the replenishment port (4). In addition, the system is complicated and large in size, including the addition of piping and pumps, which is uneconomical.

[Object of the Invention]

The present invention has been made to solve the above drawbacks, and it is an object of the present invention to provide an ion concentration analyzer which can stably use a reference electrode provided in the flow path of a test liquid for a long period of time and without maintenance. To aim.

[Outline of Invention]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, provided an internal reference electrode of a reference electrode in the flow passage of the test liquid, and used the calibration liquid of the ion selective electrode as the internal liquid. The inventors have found that the internal solution is inevitably replenished if it is filled up with the solution and always replaced with a new calibration solution, thus completing the present invention.

That is, the ion concentration analyzer of the present invention includes a flow passage for carrying a test liquid and a calibration liquid; an ion selective electrode and a reference electrode arranged so that a part of the inner wall of the flow passage is configured; A mechanism for sending the test solution and the calibration solution so that the tips thereof stop at a position between the ion-selective electrode and the reference electrode in the flow passage, and the reference electrode internally stores the calibration solution. It is characterized by being a liquid.

The ion-selective electrode according to the present invention means Na ⁺ , K ⁺ , C
The reference electrode is a saturated calomel electrode, a silver / silver chloride electrode, or the like, which is an ion selective electrode for a ²⁺ , Cl ^{− and the} like.

The calibration solution and the internal solution according to the present invention have the same composition, and serve as a calibration solution when in contact with the ion selective electrode and as an internal solution when in contact with the reference electrode. The ion-selective electrode and the reference electrode according to the present invention form a part of the flow path of the test liquid, and the calibration liquid is configured to serve as an internal liquid. It has a structure as shown in FIG. Test liquid in Fig. 1
(31) is a flow passage (3
Introduced in 4). The same applies to the calibration liquid (35). Both the test liquid (31) and the calibration liquid (35) are adapted to be introduced into the flow path (34) at the position A by a single suction operation of the pump. For example, the calibration solution (I) that was first sent in the order of solution introduction → the calibration solution (II) in which the same calibration solution was again sent → the test solution
At the time of (I) → calibration solution (II), both are the same calibration solution, but the calibration solution (I) is the role of the internal solution of the reference electrode (36).
(II) is used as a calibration solution for the ion selective electrode (37) to calibrate the reference potential. Then the test liquid is the cock (32)
When the tip is stopped by the operation of step A and the tip stops at point A, the calibration liquid (II) now plays the role of the internal liquid of the reference electrode (36), and the boundary between the test liquid and the calibration liquid (point A) is the liquid junction. Play a part. Further, the calibration liquid (I) and the calibration liquid (II) are fed and repeated analysis is performed. The ion-selective electrode (37) shown in Fig. 1 may be a multi-item flow-type ion-selective electrode instead of a single item. Further, the reference electrode may be installed upstream of the ion-selective electrode, or the calibration solution may be a KCl saturated solution or the like.

The structure of the liquid junction, which is a boundary between the ion-selective electrode, the reference electrode, and the solution provided so as to form a part of the flow passage, will be described in more detail. An example is shown in FIGS. 2 (a) and 2 (b). In FIG. 2, the reference electrode (36) and the ion selective electrode (37) are provided so as to form a part of the flow passage (34).
If the solution filled in the flow passage (34) is the calibration solution on both the B side and the C side, the calibration solution on the C side becomes the internal solution of the reference electrode (36) and passes through the liquid junction (point A). The ion selective electrode (37) will be calibrated. When the B side is the test solution and the C side is the calibration solution, the ion concentration in the test solution is measured. Further, as shown in FIG. 2 (b), when the solution on the B side and the solution on the C side are cut by air bubbles and it is difficult to form the liquid junction (point A), a salt bridge (39) should be provided in advance. Good.

If it is an analyzer that performs the above configuration and a series of operations,
The liquid junction does not become clogged, and it has the advantage that it can be used as a calibration liquid without consuming a large amount of internal liquid, and can be used stably for a long time without maintenance.

Example of Invention

An embodiment of the present invention will be described below in more detail with reference to FIG.

In the apparatus shown in FIG. 1, first, the calibration liquid (35) is a cock.
It is introduced into the flow passage (34) by the pump (33) via the (32) and stops at point A. Further, the next portion of the calibration liquid (35) is introduced into the flow passage by the pump. At this time, calibration is performed. Then, the test liquid (31) is introduced by switching the cock (32)
Stop at a point. At this time, the ion concentration of the test liquid is measured. The ion concentration measurement is completed by performing the series of operations as described above. The flow passage used in this example has an inner diameter of 1.3φ.
The length from the test solution or the calibration solution to the ion selective electrode (37) is 28 cm, and the distance between the ion selective electrode (37) and the reference electrode (36) is 8 cm using the Teflon (trademark) tube of did.
The ion-selective electrode (37) contains bis-12 in polyvinyl chloride.
A plastic membrane type Na ⁺ selective electrode (diameter 1φ, coated wire type) containing —crown-4 ether was used.
The reference electrode used was one in which a silver wire of 1φ was electrolytically oxidized to form a silver chloride layer. The calibration solution has KCl = 0.4
A tris-borate buffer solution containing mmo / NaCl = 12 mmo / was used, and the test solution used was serum diluted 10-fold with a tris-borate buffer solution.

The suction volume of the test solution and calibration solution by the pump is 580μ.
And the tip of each solution was placed between the ion-selective electrode (37) and the reference electrode (36) and had a length of 8 cm Teflon (registered trademark).
It was stopped near the middle of the tube so that the measurements of each solution were not affected by the diffusion of ions into each other. The potential difference between the ion selective electrode (37) and the reference electrode (36) is processed by the amplification / operation unit (40) and output as the ion concentration.

When 30,000 serum samples were analyzed using the ion concentration analyzer described above, stable measurement was possible without clogging of the liquid junction.

Furthermore, since the internal liquid is a calibration liquid tissue and has a composition close to the ion concentration of the test liquid, the ion pair concentration and the ion species in the internal liquid (for example, saturated KCl, NH ₄ Cl) of the conventional reference electrode are It became possible to minimize the potential difference between the liquids caused by the difference between the ion pair concentration and the ion species in the test liquid, and the measured values became more accurate.

〔The invention's effect〕

As described in detail above, by using the ion concentration analyzer of the present invention, stable ion concentration analysis can be performed for a long period of time without causing clogging of the reference electrode and without replenishing the internal electrolyte. It is a thing.

[Brief description of drawings]

1 and 2 are block diagrams of an ion concentration analyzer used in an embodiment according to the present invention and an enlarged sectional view of a part thereof, and FIGS. 3 and 4 are reference electrodes and ion concentration analysis widely used in the past. It is a block diagram which shows an example of an apparatus. 1, 36 ... Reference electrode, 2 ... Internal liquid, 3, A ... Liquid junction, 4
... internal solution replenishment port, 5 ... internal solution tank, 6,33 ... pump, 7 ... reference electrode tank, 31 ... test solution, 32 ... cock, 3
4 ... Flow path, 35 ... Calibration liquid, 37 ... Ion selective electrode,
38 ... Bubble, 39 ... Shiohashi, 40 ... Amplification / operation unit.

Claims (1)

[Claims] 1. A flow passage for carrying a test liquid and a calibration liquid; an ion selective electrode and a reference electrode arranged so that a part of an inner wall of the flow passage is configured; And a mechanism for feeding the test solution and the calibration solution so as to stop at a position between the ion-selective electrode and the reference electrode in the flow passage in which the tips of the test solution and the calibration solution are arranged. An ion concentration analyzer characterized in that a calibration solution is used as an internal solution.