JPS625650Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a liquid film type ion selective electrode. There are various types of ion-selective electrodes used in analytical methods that determine the concentration of target ions in a sample solution by bringing an ion-selective electrode and a reference electrode into contact with the sample solution and measuring the potential difference between the two electrodes. Among them, the present invention is particularly directed to liquid film type ion-selective electrodes.

A conventional liquid film type ion selective electrode has a structure as shown in FIG. In this figure, 1 is the main body plug of the ion-selective electrode, which has a through hole 2 in the center, and a sensitive membrane 3 coated on the outer surface of the plug.
A liquid membrane type ion-selective electrode is constructed by putting an electrode solution 4 into the through hole 2 and inserting an internal electrode 5 into this electrode solution. The sensitive membrane is a porous synthetic resin membrane having elasticity, such as a polypropylene membrane having a thickness of about 25 to 50 microns, and is impregnated with an ion exchange solution. The ion exchange liquid is impregnated into a sponge-like reservoir 6, and permeates through the inside of the membrane 3 from the reservoir 6 to reach the sensitive part S on the end face of the plug. This sensitive part S is brought into contact with a sample liquid, and a comparison electrode (not shown) is brought into contact with the same sample liquid to measure the electric potential between the internal electrode 5 and the comparison electrode. In the example shown in the figure, the main body plug of the ion-selective electrode is inserted into the main body block 7 of the flow-through type electrode tank, and the sensitive part S faces into the sample liquid channel 8 penetrated into the block. The lower end surface of the main body plug 1 is pressed against the seat surface 9 formed on the main body block 7, so that the sample liquid leaks out from the gap between the end surface of the plug and the seat surface 9 and does not mix with the ion exchange solution impregnated in the reservoir 6. It's becoming like that. In the figure, the ion exchange liquid is impregnated into a sponge-like reservoir 6 and permeates up to the sensitive part S of the sensitive membrane 3, but it is also applied to the space 10 between the main body block 7 and the main body plug 1. Some are designed to store ion exchange fluid.

The conventional liquid film type ion selective electrode described above has the following problems. Reservoir 6 or empty space 10
When storing the ion-exchange solution, the space 10 and the space where the sample solution exists are separated by pinching the sensitive membrane 3 between the end face of the main body plug 1 and the seat surface 9 of the main body block 7. is used as packing to prevent the flow of the liquid and prevent the sample liquid from leaking into the space 10. In order to prevent the sample liquid from leaking into the space 10 with such a structure, it is possible to increase the pressing force with which the end surface of the main body plug 1 is pressed against the seat surface 9. However, if this pressure is too large, the sensitive membrane 3 will be compressed. Due to the loss of porosity, it becomes difficult for the ion exchange liquid to permeate through the sensitive membrane 3 from the reservoir 6 or the space 10 serving as a liquid reservoir to reach the sensitive part S. Therefore, the method of applying the tightening force that presses the main body plug 1 against the seat surface 9 of the main body block is a very delicate adjustment that prevents the leakage of the sample liquid but does not prevent the permeation of the ion exchange liquid through the inside of the sensitive membrane 3. This operation was extremely difficult.

The present invention aims to solve the above-mentioned problems in liquid film type ion-selective electrodes. In this invention, a recess for holding the ion exchange liquid is provided in the main body plug of the ion-selective electrode, and the recess is covered with a sensitive membrane, thereby separating the space where the sample liquid exists and the space where the ion exchange liquid is held using the sensitive membrane. The present invention provides a liquid film type ion-selective electrode. The present invention will be explained below with reference to Examples.

FIG. 2 shows an embodiment of the present invention.
This embodiment is an example in which a liquid film type ion selective electrode is installed in a flow-through type ion electrode tank, and parts corresponding to those in FIG. 1 are given the same numbers.
The main body plug 1 is attached to the main body block 7 of the ion electrode tank.
A recess 11 with a flat bottom is provided into which the plug is inserted, and this flat bottom serves as a seat surface 9 against which the end face of the body plug is pressed. The main body plug 1 has a flat lower end, a vertical through hole 2 in the center, and an annular recess 12 formed around the vertical through hole 2 on the lower end surface, and this recess is used for ion exchange. It is a hollow space that holds liquid. The recess 12 is filled with a sponge-like ion-exchange fluid-containing material 13, and in this state, the sensitive membrane 3 is attached to cover the outer surface of the plug 1. 15 is an elastic ring that fixes the sensitive membrane 3 to the main body plug 1. The vertical through hole 2 contains a sensitive liquid 4 and the internal electrode 5 is inserted therein, as in the conventional example.

A shallow recess 14 is provided at the center of the bottom of the recess 11 in the electrode chamber body block 7 at a position opposite to the vertical through hole 2 of the plug 1. When viewed from the side, the sensitive membrane 3, which forms a curved flow path as shown in the figure and covers the lower end surface of the main body plug 1, serves as a cover for the recess 14, and this part of the sensitive membrane 3 is the sensitive part S. The main body plug 1 is fastened to the main body block 7 by screws 16, and the sensitive membrane 3 is pressed between the lower end surface of the plug 1 and the seat surface 9 to prevent leakage of the sample liquid.

As mentioned above, in the liquid membrane type ion-selective electrode of the present invention, the ion exchange liquid is located on the opposite side of the electrode membrane 3 from the sample liquid, and the sample liquid and the ion exchange liquid held in the reservoir are directly mixed. Since there is no risk of this happening, the force for pressing the main body plug 1 against the seat surface can be light.
Therefore, the supply of the ion exchange liquid to the sensitive part S of the sensitive membrane is carried out smoothly, and the tightening force of the main body plug is carefully adjusted to balance the supply of the ion exchange liquid and the prevention of mixing with the ion exchange liquid due to leakage of the sample liquid. This eliminates the difficulty of having to make adjustments.

The ion-exchange fluid holding recess 12 provided in the main body plug 1 is not limited to the one provided on the lower end surface of the plug as in the above embodiment, but may be formed on the peripheral side surface of the plug main body. As in the above-mentioned embodiment, the recess 12 is provided at a position facing the seat surface 9 of the main body block, and the ion exchange liquid is contained in a resilient sponge-like material and is loaded into the recess 12, and the lower end surface of this sponge is If the sponge is made to protrude slightly from the lower end surface of the plug in its natural state, this sponge will elastically move the sensitive membrane to the seat surface 9.
Since the sensitive membrane 3 and the seat surface 9 are pressed against each other, the contact between the sensitive membrane 3 and the seat surface 9 is improved, and even if the tightening force of the plug 1 is lighter, liquid leakage is prevented and the plug tightening operation becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view of a conventional example, and FIG. 2 is a longitudinal side view of a liquid film type ion-selective electrode according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Ion selective electrode main body plug, 3... Electrode membrane, 6... Reservoir, S... Sensing part, 7... Ion selective electrode tank main body block, 8... Sample liquid flow path, 12... Ion Recess for holding replacement fluid.

Claims (1)

[Scope of utility model registration request] A recess for holding an ion exchange liquid is provided in the main body plug of the ion selective electrode, and a sensitive film is applied to the main body plug, covering the main body plug widely from the end face to the side face, including this recess, and the end face of the main body plug is covered with a sensitive film. is brought into contact with the opposing seating surface via the sensitive membrane, and the sensitive membrane is made to face the sample liquid space through the opening in the center of the seating surface, and the sensitive membrane covers the side surface of the main body plug. A liquid film type ion-selective electrode whose side that does not come in contact with the main body plug is open to a space isolated from the sample liquid.