WO2015093563A1

WO2015093563A1 - Electrode unit and liquid junction member

Info

Publication number: WO2015093563A1
Application number: PCT/JP2014/083558
Authority: WO
Inventors: 伊東　哲; 澤崎　毅; 範広森川; 英二根岸; 良夫武田; 浩瀬戸口
Original assignee: 東亜ディーケーケー株式会社
Priority date: 2013-12-18
Filing date: 2014-12-18
Publication date: 2015-06-25
Also published as: CN105829878A; CN105829878B; JPWO2015093563A1; JP6319324B2

Abstract

Provided are an electrode unit that has a simple structure and makes it possible to easily exchange a liquid junction unit, and a liquid junction member used in the electrode unit. An electrode unit (100) is provided with a tubular container (1) that forms an internal liquid container part (2) for accommodating an internal liquid (S1) and has an opening part (11) at which the internal liquid container part (2) is open, a liquid junction part (3) for exuding the internal liquid (S1) accommodated in the internal liquid container part (2) to the outside, and an internal reference electrode (51) disposed inside the container. The liquid junction part (3) is configured from a liquid junction member (30) that has an engaging part (32) for engaging with the container (1) and is detachably attached to the container (1) so as to close the opening part (11).

Description

Electrode body and liquid junction member

The present invention relates to an electrode body used as a unipolar reference electrode or composite electrode in electrochemical measurements such as pH measurement, ion concentration measurement, and oxidation-reduction potential measurement, and a liquid junction member used in the electrode body.
The present invention claims priority based on Japanese Patent Application No. 2013-261774 filed in Japan on December 18, 2013, the contents of which are incorporated herein by reference.

Conventionally, a reference electrode used for pH measurement or the like has been provided with a liquid junction (junction), and an internal liquid (solution or component thereof) oozes out from the liquid junction into the test solution. The test solution is electrically connected.

There are various types of liquid junctions, but liquid junctions formed of porous members are widely used. In particular, a liquid junction formed of a porous ceramic (porous ceramic) is widely used as a porous member. The liquid junction of the porous ceramic is generally cylindrical (round bar shape), and is sealed in the wall of the container at the lower end of the container such as a support tube that forms the internal liquid container. Used.

Moreover, there is a liquid junction formed of a resin (porous resin) such as porous polytetrafluoroethylene (PTFE) as a porous member (Patent Document 1). Furthermore, it has also been proposed to use a porous ceramic and a porous resin in combination as a liquid junction (Patent Document 2).

Japanese Patent No. 4234856 JP 2012-47692 A

The amount of the component of the internal liquid that has passed through the liquid junction is an important factor in the electrical stability of the reference electrode. And since a liquid junction part gets dirty by use, exchange may be needed.

However, for example, the liquid junction formed of, for example, a porous ceramic is generally fixedly enclosed in a wall made of glass, adhesive, or the like of the container that forms the internal liquid storage unit, so that it can be easily replaced. It is not possible. For this reason, it is necessary to replace the electrode body as a single electrode comparison electrode or a composite electrode, which may be wasteful. It is also known that the liquid junction support is supported on the electrode body (electrode body), which is detachable from the electrode body, and the entire liquid junction support is exchanged. Since only a certain liquid junction is not replaced, waste may occur depending on the structure.

On the other hand,

Patent Documents

1 and 2 describe a configuration in which a liquid junction formed of a porous resin can be removed from a support tube that forms an internal liquid storage unit. However, in this configuration, the liquid junction portion is a nut-like member and is fixed to the support tube forming the internal liquid storage portion, so that the structure of the electrode body is likely to be complicated.

Therefore, an object of the present invention is to provide an electrode body in which the liquid junction portion can be easily replaced with a simple configuration, and a liquid junction member used in the electrode body.

The above object is achieved by the electrode body and the liquid junction member according to the present invention. In summary, the present invention includes a tubular container having an opening for forming an internal liquid storage part for storing an internal liquid and opening the internal liquid storage part, and an engagement part for engaging with the container. A liquid junction member that is detachably attached to the container so as to seal the opening, a liquid junction part that exudes the internal liquid stored in the internal liquid storage part to the outside, and an inside of the container An electrode body comprising: a reference electrode inner electrode disposed.

According to another aspect of the present invention, a tubular container having an opening for forming an internal liquid storage portion for storing an internal liquid and opening the internal liquid storage portion, and the internal liquid stored in the internal liquid storage portion are provided. A liquid junction member constituting the liquid junction part of an electrode body including a liquid junction part to be leached to the outside and a reference electrode inner electrode disposed inside the container, and engaging with the container. There is provided a liquid junction member having a joint and detachable from the container so as to seal the opening.

According to the electrode body of the present invention and the liquid junction member used for this electrode body, the liquid junction member itself constituting the liquid junction part is detachable from the container forming the internal liquid storage part, so that it is simple. With the configuration, the liquid junction can be easily replaced. Further, by preparing a plurality of types of liquid junction members having different characteristics, it becomes possible to select and use a liquid junction member having a desired characteristic according to the purpose of use of the electrode body.

It is a fragmentary sectional view of the electrode body concerning one example of the present invention. It is sectional drawing and a top view of the liquid junction member used for the electrode body which concerns on one Example of this invention. It is a top view which shows an example of multiple types of liquid junction member. It is a perspective view of the jig | tool used for attachment or detachment of a liquid junction member in one Example of this invention. It is a fragmentary sectional view of the electrode body concerning other examples of the present invention.

Hereinafter, the electrode body and the liquid junction member according to the present invention will be described in more detail with reference to the drawings.

1. Electrode Body First, an overall configuration of an electrode body according to an embodiment of the present invention will be described. FIG. 1 is a partial cross-sectional view of an embodiment of an electrode body according to the present invention. In this embodiment, the electrode body is a composite electrode for pH measurement.

The electrode body 100 of the present embodiment has an opening 11 for forming an internal liquid storage part 2 for storing a reference electrode internal liquid (hereinafter also simply referred to as “internal liquid”) S1 and opening the internal liquid storage part 2. It has a tubular container 1 provided, and a liquid junction part 3 for leaching the internal liquid S1 stored in the internal liquid storage part 2 to the outside. In this embodiment, the liquid junction portion 3 has an engagement portion 32 that engages with the container 1 and is detachably attached to the container 1 so as to seal the opening 11 of the container 1. 30.

More specifically, in this embodiment, the composite electrode 100 as an electrode body is formed in a rod shape having a long axis in one direction as a whole, and roughly, the measurement electrode 4, the comparison electrode 5, the temperature sensor 6, Have.

The measurement electrode (pH glass electrode) 4 is a sensitive portion 41 that is a pH glass sensitive film, an inner tube 42 as a support that supports the sensitive portion 41, and an internal electrode that is disposed inside the inner tube 42. A measurement electrode inner electrode 43. The inner electrode 42 contains a measurement electrode inner liquid S2, and the measurement electrode inner electrode 43 is immersed in the measurement electrode inner liquid S2. In the present embodiment, the inner tube 42 is a linear tubular member made of glass having a substantially circular cross section as viewed along the axial direction of the composite electrode 100 and having a substantially uniform inner and outer diameter. . The inner tube 42 is disposed along the axial direction of the composite electrode 100, and a hemispherical sensitive portion 41 is welded to and integrated with one end portion of the inner tube 42.

The comparison electrode 5 has an outer tube 1 as a container, a liquid junction member 30 constituting the liquid junction portion 3, and a comparison electrode inner electrode 51 which is an internal electrode arranged inside the outer tube 1. The internal liquid S2 is stored in the internal liquid storage portion 2 that is an annular space formed by the outer tube 1, the inner tube 42, and the liquid junction member 30. It is immersed in the liquid S1. In this embodiment, the outer tube 1 is an insulating member made of resin or plastic (in this embodiment, having a substantially uniform inner diameter and outer diameter, having a substantially circular cross section viewed along the axial direction of the composite electrode 100. It is a linear tubular member made of polysulfone resin. The outer tube 1 is disposed along the axial direction of the composite electrode 100, and the liquid junction member 30 is detachably mounted so as to seal the opening 11 provided at one end of the outer tube 1 in the axial direction. Has been. The measurement electrode 4 extends along the axial direction of the outer tube 1, and the sensitive portion 41 of the measurement electrode 4 is exposed to the outside of the liquid junction member 30. The liquid junction member 30 will be described in detail later.

As a component of the internal liquid S1, potassium chloride (KCl) can be used. Most frequently used are KCl solutions with a high concentration (from 3 mol / L to saturation). In this example, a saturated KCl solution was used. The internal liquid S1 may be made into a gel or sol form by adding a thickener as desired. Here, exuding the internal liquid S1 through the liquid junction 3 includes both flowing out the internal liquid S1 as a solution and flowing out (diffusing) only the components of the internal liquid S1.

The temperature sensor 6 is immersed in the internal liquid S1 stored in the internal liquid storage unit 2.

Each signal from the measurement electrode inner electrode 43 of the measurement electrode 4, the comparison electrode inner electrode 51 of the comparison electrode 5, and the temperature sensor 6 passes through the inside of the electrode cap 7 and is transmitted to the outside by the lead wire 8. It has become.

2. Liquid junction member Next, the liquid junction member 30 in a present Example is demonstrated. FIG. 2 is a cross-sectional view and a plan view showing the liquid junction member 30 in the present embodiment in more detail. 2 (a) is a cross-sectional view taken along line AA in FIG. 2 (c), FIG. 2 (b) is a cross-sectional view taken along line BB in FIG. 2 (c), and FIG. It is the top view seen along the axial direction of composite electrode 100 from the inside lower part.

In the present embodiment, the liquid junction member 30 is detachably attached to the outer tube 1 along the axial direction of the outer tube 1 so as to seal the opening 11 provided at one end of the outer tube 1 in the axial direction. It is said that. In the present embodiment, since the measurement electrode 4 is disposed inside the outer tube 1, the liquid junction member 30 is a stepped ring-shaped member having a through hole 38 through which the measurement electrode 4 is inserted. .

More specifically, the liquid junction member 30 includes a small-diameter portion 31 in which a male screw (thread portion) 32 as an engaging portion that engages with the outer tube 1 is formed on the outer peripheral surface, and a large-diameter that is larger in diameter than the small-diameter portion 31. Part 33. The male screw 32 of the liquid junction member 30 is screwed into a female screw (threaded portion) 12 as an engaging portion formed on the inner peripheral surface near the opening 11 of the outer tube 1. Further, the outer diameter of the outer peripheral surface of the large-diameter portion 33 is substantially equal to the inner diameter of the inner peripheral surface adjacent to the opening 11 of the outer tube 1, and the large-diameter portion 33 is formed by screwing the male screw 32 to the female screw 12. It is fitted in the outer tube 1. Further, a through hole 38 is formed in the liquid junction member 30 so as to penetrate the small diameter portion 31 and the large diameter portion 33 along the axial direction of the outer tube 1. The inner diameter of the through hole 38 is substantially equal to the outer diameter of the inner tube 42 of the measurement electrode 4, and the sensitive part 41 of the measurement electrode 4 passes through the through hole 38 when the liquid junction member 30 is attached to the outer tube 1. Exposed outside. The first groove 34a formed on the outer peripheral surface of the boundary portion between the small diameter portion 31 and the large diameter portion 33 is sealed as a seal member that seals the space between the outer tube 1 and the liquid junction member 30 in a liquid-tight manner. One O-ring 35a is attached. Further, a second O-ring 35 b as a seal member for sealing the space between the measurement electrode 4 and the liquid junction member 30 is attached to the second groove portion 34 b formed on the inner peripheral surface of the through hole 38. ing.

In the liquid junction member 30, the first end surface 36 on the small diameter portion 31 side is in contact with the internal liquid S1 in the internal liquid storage portion 2, and the second end surface 37 on the large diameter portion 33 side is in contact with the test liquid (sample). . Then, the internal liquid S1 diffuses from the first end face 36 to the entire liquid junction member 30, and then oozes out to the external test liquid. Thereby, electrical conduction between the reference electrode inner electrode 51 and the test solution is established.

Thus, according to the present embodiment, the liquid junction part 3 of the comparative electrode 5 is constituted by the liquid junction member 30 that can be easily attached to and detached from the electrode body. Thereby, the composite electrode 100 has a simple configuration, and when the liquid junction portion 3 becomes dirty due to use, only the liquid junction portion 3 that really needs to be replaced can be easily replaced. The replacement of only the liquid junction part 3 is not only the replacement of all the members constituting the liquid junction part 3 (the liquid junction member 30 made of a porous member and other accessories such as the

seal members

35a and 35b). In addition, only the liquid junction member 30 that is the main body of the liquid junction portion 3 is replaced. In addition, according to the present embodiment, the liquid junction member 30 constitutes the lid of the internal liquid storage unit 2, so that, for example, when the liquid junction member 30 is replaced or the liquid junction member 30 is simply removed as a lid, The internal liquid S1 can be replenished (filled) in the internal liquid storage unit 2 or replaced.

Here, in this embodiment, the liquid junction member 30 is made of a porous resin and has a first liquid junction portion 30A formed with a male screw 32, and is made of porous ceramic and penetrates the first liquid junction portion 30A. And a second liquid junction portion 30B embedded in the first liquid junction portion 30A. In the present embodiment, the first liquid junction from the first end surface 36 to the second end surface 37 along the axial direction of the outer tube 1 is formed on the stepped ring-shaped first liquid junction portion 30A as described above. A column-shaped (cylindrical in this embodiment) second liquid junction portion 30B is embedded so as to penetrate the portion 30A. As will be described later, the number of second liquid junction portions 30B may be singular or plural. In the example shown in FIG. 2, the two second liquid junction portions 30 </ b> B are arranged at positions facing each other with the through hole 38 interposed therebetween. The internal liquid S1 exudes into the test liquid through the first liquid junction part 30A and the second liquid junction part 30B.

Thus, in the present embodiment, the liquid junction member 30 has a hybrid structure in which the first liquid junction portion 30A formed of porous resin and the second liquid junction portion 30B formed of porous ceramic are combined. (Hybrid liquid junction member). In general, the first liquid junction portion 30A formed of the porous resin is likely to have non-uniform porosity and pore diameter, easily change in pore diameter due to temperature change, and easily change the oozing amount of the internal liquid S1. It is easy to increase the wetted area. On the other hand, the second liquid junction portion 30B formed of porous ceramic is generally difficult to increase the liquid contact area, but the porosity and the pore diameter are relatively uniform, and the pore diameter is changed by temperature change. It is difficult to change, and the amount of exudation of the internal liquid S1 is difficult to change. Therefore, by making the liquid junction member 30 have a hybrid structure, even if bubbles and dirt adhere to the second liquid junction part 30B, bubbles and dirt are attached to the entire first liquid junction part 30A at the same time. Since it is rare, it is possible to prevent the comparative electrode 5 from suddenly becoming unusable. Further, even if the amount of the internal liquid S1 exuded from the first liquid junction portion 30A changes due to a temperature change or the like, it is easy to obtain electrical stability due to the internal liquid exudation through the second liquid junction portion 30B. It is possible to prevent the comparison electrode 5 from suddenly becoming unusable. In addition, since the first liquid junction portion 30A formed of the porous resin can increase the liquid contact area, bubbles and dirt may be partially attached (clogged). , Because it is unlikely to cover the whole, it can be used for a relatively long time.

In addition, according to the present embodiment, the liquid junction member 30 can be easily attached to and detached from the electrode main body. Therefore, by preparing a plurality of types of liquid junction members 30 having different characteristics, the electrode can be formed from among them. The liquid junction member 30 having desired characteristics can be selected and used in accordance with the purpose of use of the body (type of test liquid).

That is, the liquid junction is generally designed optimally for a single purpose of use of the electrode body. However, there are various measurement targets for electrode bodies such as composite electrodes for pH measurement, such as environmental water, water and sewage, drainage, process water, and it is difficult to cover all targets with a single liquid junction. is there. In addition, performance (low liquid junction asymmetric potential, high temperature and high pressure resistance) and electrode life often have a trade-off relationship. A liquid junction formed of a porous resin is generally resistant to oil stains and dirt due to adhesion of fine particles, but is inferior in stability of diffusion of internal liquid and has a large liquid junction asymmetric potential. On the other hand, the liquid junction formed of porous ceramic has a low liquid junction asymmetry potential and is stable to a test solution with low electrical conductivity, but it is clogged with oily dirt and particulate contaminants. easy. Here, for example, the liquid junction formed of porous PTFE as a porous resin can be produced by mixing KCl particles with PTFE and firing, but by controlling the particle size and mixing ratio of the KCl particles. The balance between performance and life can be adjusted by adjusting the pore diameter and porosity. Further, for example, a liquid junction formed of porous alumina as a porous ceramic can adjust the pore size and porosity by controlling the particle size of alumina and the firing temperature, thereby adjusting the balance between performance and life.

Therefore, (1) different types (for example, at least one of pore diameter, porosity, shape, and size) of the first liquid junction portion 30A formed of the porous resin, (2) the porous ceramic By changing the type (for example, at least one of pore diameter, porosity, number, shape and size) of the formed second liquid junction portion 30B, or (3) by changing both of these, It is possible to design the liquid junction member 30 suitable for various uses of the body. As the shape or size of the first liquid junction portion 30A, for example, the length in the direction along the axial direction of the container 1 (amount of exposure to the outside of the opening) can be varied. Further, as the shape or size of the second liquid junction portion 30 </ b> B, the cross-sectional shape or diameter in the direction intersecting the axial direction of the container 1 can be varied.

For example, as shown in FIGS. 3A to 3C, three types of liquid junction members 30 in which the number of second liquid junction portions 30B is changed to one, two, and four are prepared. In this case, typically, as the number of the second liquid junction portions 30B is larger (that is, the liquid contact area of the second liquid junction portion 30B is larger and the liquid contact area of the first liquid junction portion 30A is smaller). It can be positioned as performance priority. Conversely, the smaller the number of the second liquid junction portions 30B (that is, the smaller the liquid contact area of the second liquid junction portion 30B and the larger the liquid contact area of the first liquid junction portion 30A), the life priority is given. Can be positioned. In addition, by confirming the number of the second liquid junction portions 30B in this way, it becomes possible to confirm whether the performance priority or the life priority is given from the appearance, and the user can more easily select the desired liquid junction member 30. Is possible.

For example, as the material of the first liquid junction portion 30A, a fluororesin, a polyethylene resin, or a polypropylene resin can be used. Examples of the fluororesin include PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), FEP (perfluoroethylene propene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), and the like. A fluororesin such as PTFE is preferable in that it has a water repellency, so that even if the pore diameter is relatively large and the liquid contact area is widened, the amount of exudation does not become excessive. Further, being water-repellent, being able to increase the hole diameter, and being able to increase the area is advantageous from the viewpoint of preventing clogging due to dirt or the like. In this example, PTFE was used. The first liquid junction portion 30A is roughly composed of a PTFE powder and a dried KCl powder having a uniform particle size mixed at a predetermined mixing ratio, pressure-fired using a mold, and machined as necessary. After processing (cutting etc.), it can be produced by immersing in water (or hot water) to dissolve and remove KCl in PTFE. In addition, when using polyethylene resin or polypropylene resin, it is generally a method of fusing (sintering) only the vicinity of the surface layer of each raw material powder, and molding while leaving the voids existing between the raw material powders. A porous member can be produced.

For example, as the material of the second liquid junction portion 30B, various ceramics such as alumina, cerium, magnesia, zirconia and the like may be mentioned depending on the ceramic composition. In this embodiment, alumina ceramic is used. Using. Porous ceramics having appropriate porosity and pore diameter are commercially available as the liquid junction of the reference electrode in electrochemical measurement. The second liquid junction part 30B can be embedded in the first liquid junction part 30A as follows, for example. That is, a through hole having an inner diameter slightly smaller than the outer diameter of the cylindrical porous ceramic constituting the second liquid junction portion 30B at a desired position of the first liquid junction portion 30A formed as described above. Is drilled by machining. And the porous ceramic cut out to predetermined length as the 2nd liquid junction part 30B is press-fit in the length direction to this through-hole. As a result, the first liquid junction part 30A and the second liquid junction part 30B are fixed in close contact by friction engagement.

3. Attachment / detachment of the liquid junction member In this embodiment, the liquid junction member 30 is screwed to the outer tube 1 via the female screw 12 of the outer tube 1 and the male screw 32 of the liquid junction member 30 as described above. In the present embodiment, as shown in FIG. 1, when the liquid junction member 30 is attached to the outer tube 1, the second end surface 37 of the liquid junction member 30 is a plane including the opening 11 of the outer tube 1. And are arranged so as to be substantially in the same plane. In this state, in order to attach / detach the liquid junction member 30 to / from the outer tube 1, it is difficult to pick and rotate the liquid junction member 30 with a finger or the like.

Therefore, in the present embodiment, as shown in FIG. 2, the liquid junction member 30 is connected to the second end surface 37, which is the end surface opposite to the internal liquid storage portion 2 in the axial direction of the outer tube 1. An engagement hole 39 is formed as a rotational force transmitting portion that transmits rotational force applied from a member that rotates 30. The number of the engagement holes 39 may be single or plural. In the present embodiment, four engagement holes 39 are formed at substantially equal angular intervals around the through hole 38 on the second end surface 37 of the liquid junction member 30. The engagement hole 39 is formed in the first liquid junction portion 30A so as to avoid the second liquid junction portion 30B.

FIG. 4 is a perspective view of an example of a jig 200 used for attaching / detaching the liquid junction member 30 to / from the outer tube 1 in this embodiment. The jig 200 has a linear tubular shape whose outer diameter is substantially equal to the outer diameter of the second end surface 37 of the liquid junction member 30 and whose inner diameter is substantially equal to or larger than the outer diameter of the inner tube 42 of the measuring electrode 4. It has a jig body 201 which is a member. Further, the jig 200 has an engagement protrusion 203 that is provided on one end surface 202 of the jig body 201 and engages with the engagement hole 39 of the liquid junction member 30. In this embodiment, four engagement protrusions 203 are provided corresponding to the engagement holes 39.

When the liquid junction member 30 is attached to the outer tube 1, the liquid junction member 30 is picked with a finger or the like and screwed into the outer tube 1 halfway or from the beginning to the engagement hole 39 of the liquid junction member 30. The jig 200 is rotated by engaging the engagement protrusion 203 of the tool 200. The rotational force of the jig 200 is transmitted to the liquid junction member 30 via the engagement protrusion 203 and the engagement hole 39. Thus, the liquid junction member 30 can be screwed into the outer tube 1 by rotating it with the jig 200. At this time, as the liquid junction member 30 enters the outer tube 1, the measurement electrode 4 protruding from the second end surface 37 through the through hole 38 of the liquid junction member 30 escapes to the central hole portion 204 of the jig 200. Does not interfere with operation. When the liquid junction member 30 is removed from the outer tube 1, the operation may be performed roughly in reverse to that at the time of mounting.

As described above, according to the present embodiment, the liquid junction member 30 constituting the liquid junction portion 3 itself is detachable with respect to the outer tube (container) 1 forming the internal liquid storage portion 2, so that the configuration is simple. The liquid junction 3 can be easily replaced. In addition, by preparing a plurality of types of liquid junction members 30 having different characteristics, the liquid junction member 30 having desired characteristics can be selected and used according to the purpose of use of the electrode body 100.

Next, another embodiment of the present invention will be described. In this embodiment, the electrode body is a unipolar reference electrode.

FIG. 5 is a partial cross-sectional view of a comparative electrode 300 as an electrode body in the present embodiment. 5, elements having the same or corresponding functions and configurations as those of the composite electrode 100 in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

The comparative electrode 300 of this example is roughly equivalent to the composite electrode 100 in Example 1 excluding the measurement electrode 4. In the present embodiment, the liquid junction part 3 of the comparison electrode 300 is constituted by a liquid junction member 30 that is detachably attached to a support tube 1 as a container that forms the internal liquid storage part 2. In the present embodiment, the liquid junction member 30 is not provided with the through hole 38 provided for inserting the measurement electrode 4 in the first embodiment.

Thus, the present invention can be applied to a unipolar reference electrode, and the same effects as those of the first embodiment can be obtained.

Others While the present invention has been described with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

For example, a container that forms the internal liquid storage portion is provided with a liquid junction member holding portion having an opening that extends in a direction intersecting the axial direction, and the liquid junction member is detachably attached thereto. It can also be. However, as in the above-described embodiment, by making the liquid junction member detachable from the opening at the end of the tubular container, the structure can be made extremely simple and the manufacturing can be facilitated.

Further, in the above-described embodiment, the liquid junction member is screwed into the container forming the internal liquid storage portion, but the engagement mode between the container and the liquid junction member is not limited to screwing. For example, the liquid junction member and the container can be fixed by friction engagement by press-fitting the liquid junction member into the container (press-fit type). Moreover, the liquid junction member and the container can be fixed by elastically engaging the concave portion (or convex portion) provided in the container and the convex portion (or concave portion) provided in the liquid junction member. Yes (snap fit type). Further, the container and the liquid junction member are brought close to each other with the plurality of claws provided in the container and the liquid junction member being shifted, and then the container and the liquid junction member are relatively rotated to By engaging the claws, the liquid junction member and the container can be fixed (bayonet type).

Further, in the above-described embodiment, the liquid junction member has a hybrid structure having a first liquid junction portion formed of a porous resin and a second liquid junction portion formed of porous ceramic. By making the liquid junction member have a hybrid structure, the advantageous effects as described above can be obtained, but the liquid junction member is not limited to the hybrid structure. For example, the liquid junction member can be made entirely of a porous resin in the same manner as the first liquid junction portion in the above-described embodiment, without providing the second liquid junction portion in the above-described embodiment.

In the above-described embodiment, the end surface of the liquid junction member on the test liquid side is arranged so as to be substantially the same plane as the plane including the opening of the container. However, the present invention is not limited to this. The end surface of the liquid junction member on the test liquid side may be disposed inside the opening of the container or may be disposed outside. When the end surface on the test liquid side of the liquid junction member is arranged outside the opening of the container, the liquid contact area of the liquid junction can be increased, and the attachment operation can be performed by picking it with a finger or the like. Becomes easier.

Further, the present invention may be applied to a differential sensor known in the art. For example, the differential pH sensor has two pH glass electrodes, one pH glass electrode is used as a measurement electrode, and the other pH glass electrode is provided as a comparison electrode. The pH glass electrode provided in the comparison electrode is immersed in a pH buffer solution accommodated in the electrode chamber, and is electrically connected to the test solution through the salt bridge chamber provided adjacent to the electrode chamber. It has come to be taken. These salt bridge chambers, electrode chambers, and pH glass electrodes in the electrode chambers constitute a comparative electrode. The salt bridge chamber has a double junction structure having an internal liquid storage portion for storing the internal liquid, a liquid junction portion on the test solution side, and a liquid junction portion on the electrode chamber side. Therefore, according to the present invention, at least the internal liquid storage part of the salt bridge chamber is formed with the container according to the present invention, and the liquid junction part on the test liquid side in the double junction structure is configured with the liquid junction member according to the present embodiment. An electrode body can be constituted. It should be noted that the present invention can be applied in the same manner as described above even when the single electrode comparison electrode or the composite electrode comparison electrode adopts a double junction structure, not limited to the differential sensor. When the double junction structure is adopted, the internal liquid may be a chemical species that can carry electric charge, and KNO ₃ or the like can also be used.

In the above-described embodiments, the measurement electrode is described as being a pH measurement electrode, but the present invention is not limited to this. Examples of the measurement electrode include a pH measurement electrode, an ion concentration measurement electrode, and an oxidation-reduction potential measurement electrode. The electrode body according to the present invention is, for example, a monopolar reference electrode used together with these pH measurement electrode, ion concentration measurement electrode, oxidation-reduction potential measurement electrode, or a composite having these measurement electrode and comparison electrode integrally. It can be an electrode.

1 Outer tube (container)
2 Internal liquid storage part 3 Liquid junction part 4 Measuring electrode 5 Reference electrode 30 Liquid junction member 100 Composite electrode (electrode body)
200 Jig 300 Monopolar reference electrode (electrode body)

Claims

A tubular container having an opening for forming an internal liquid storage portion for storing the internal liquid and opening the internal liquid storage portion;
It is constituted by a liquid junction member that has an engaging portion that engages with the container and is detachably attached to the container so as to seal the opening, and the internal liquid accommodated in the internal liquid accommodating part is externally provided. Liquid junctions to ooze into,
A reference electrode inner electrode disposed inside the container;
An electrode body comprising:
The opening is provided at one end of the container in the axial direction, and the liquid junction member is detachable from the container along the axial direction of the container. An electrode body according to 1.
A measurement electrode extending along the axial direction of the container is disposed inside the container, and the liquid junction member is a ring-shaped member having a through hole through which the measurement electrode is inserted. The electrode body according to claim 2.
The liquid junction member is screwed into the container, and the rotational force is transmitted to the end surface opposite to the internal liquid container in the axial direction of the container. The electrode body according to claim 2, wherein a portion is formed.
The liquid junction member is made of a porous resin and has the first liquid junction part formed with the rotational force transmitting portion, and the first liquid junction part is made of porous ceramic and penetrates the first liquid junction part. 5. The electrode body according to claim 1, further comprising a second liquid junction portion embedded in the liquid junction portion.
A tubular container having an opening for forming an internal liquid storage portion for storing the internal liquid and opening the internal liquid storage portion; a liquid junction portion for leaching the internal liquid stored in the internal liquid storage portion; A liquid junction member that constitutes the liquid junction part of the electrode body including a reference electrode inner electrode disposed inside the container,
A liquid junction member having an engaging portion that engages with the container and being detachable from the container so as to seal the opening.
The liquid according to claim 6, wherein the liquid is detachable from the container along the axial direction of the container so as to seal the opening provided at one end of the container in the axial direction. Tangle member.
The liquid junction member according to claim 7, wherein the liquid junction member is a ring-shaped member having a through-hole through which a measurement electrode that is arranged inside the container and extends along the axial direction of the container is inserted.
A rotational force transmitting portion for transmitting a rotational force applied at the time of attachment / detachment is formed on an end surface of the container opposite to the internal liquid storage portion in the axial direction of the container. The liquid junction member according to claim 7 or 8, characterized in that.
A first liquid junction part made of a porous resin and formed with the rotational force transmission part and a porous ceramic part embedded in the first liquid junction part so as to penetrate the first liquid junction part The liquid junction member according to any one of claims 6 to 9, further comprising a second liquid junction portion.