JP6216689B2 - Reference electrode - Google Patents

Description

  The present invention relates to a reference electrode used in an electrochemical measurement device such as a pH measurement device.

  Electrochemical measurement apparatuses using a glass electrode method such as a pH measurement apparatus are provided with a measurement electrode and a comparison electrode. Although there are various configurations as the comparison electrode, for example, in the one shown in Patent Document 1, in the internal liquid chamber of the comparison electrode, the inner pole is arranged so as to extend upward from the lower end, and the upper portion of the internal liquid chamber A flow path in which the measurement liquid flows horizontally is formed in the space, and a partition is provided between the flow path and the internal liquid chamber. The partition wall is provided with a cylindrical liquid junction portion penetrating vertically, and an upper portion of the liquid junction portion is opened. Since this opening is arranged in parallel with the flow of the measurement liquid, in such a case, if bubbles are included in the measurement liquid, the bubbles flowing through the flow path are caught by the entire opening and remain. Sometimes. In this case, there is a problem that the bubbles block the conduction between the measurement liquid and the internal liquid at the liquid junction, making it impossible to measure the potential of the measurement liquid or becoming unstable.

  In addition, when a fiber-like conduction member such as a cloth is provided on the entire liquid junction, air bubbles may be caught on the cloth and remain in this case. In some cases, the above-described problem may occur.

Japanese Utility Model Application Publication No. 59-183655

  Therefore, the present invention has been made to solve the above problems, and even when bubbles are mixed in the measurement liquid, the connection between the internal liquid and the measurement liquid is maintained at the liquid junction, and The main problem is that the potential measurement can be performed stably.

  That is, the comparative electrode according to the present invention includes an internal liquid chamber in which an internal liquid is accommodated, and a liquid junction disposed in the internal liquid chamber so that the internal liquid and the measurement liquid to be measured are in contact with each other. A body provided, and an internal electrode disposed in the internal liquid chamber, wherein the liquid junction is adjacent to the conductive member formed from a porous or fibrous member. It is formed from an opening.

With such a configuration, since the liquid junction is formed from the conducting member and the opening adjacent to the conducting member, when the measurement liquid flows into the liquid junction, the measuring liquid is on the opening side. When the measurement liquid contains bubbles, the bubbles are likely to stay at the opening along the flow.
Therefore, the conducting member is not covered with bubbles, and the measurement liquid penetrates into the porous member or fiber of the conducting member and comes into contact with the internal liquid to maintain the conduction between the measurement liquid and the internal liquid. Potential measurement can be performed stably.

  If the size of the opening is made larger than the size of the fine hole of the conducting member, the effect of the present invention can be reliably achieved.

  Further, in order to prevent bubbles from remaining in the end portion of the conducting member that comes into contact with the measuring solution by bubbles contained in the measuring solution, the end portion that comes into contact with the measuring solution in the conducting member is It is preferable that they are arranged so as to be substantially flush with the opening or so as to protrude from the opening toward the measuring solution.

  In order to allow the internal liquid to permeate the conducting member even when bubbles accumulate in the entire liquid junction, it is preferable that the conducting member is provided extending in the internal pole direction.

  As a specific aspect of the arrangement of the openings, when the measurement liquid flows in one direction through the measurement liquid storage portion in which the measurement liquid is stored, the opening is downstream of the flow of the measurement liquid. The one arranged in is mentioned.

  As a specific aspect of the arrangement of the conducting member in the internal liquid chamber, the measurement liquid storage portion is located above the internal liquid chamber, above the upper end of the internal electrode, The internal liquid chamber is formed such that the cross-sectional area of the internal liquid chamber from the upper end to a predetermined distance is smaller than the cross-sectional area below the position at the predetermined distance, and the conducting member is the liquid junction What is arrange | positioned between the said predetermined distance from a part is mentioned.

According to the present invention configured as described above, since the liquid junction part is provided with the conducting member and the opening, the measurement liquid easily enters the opening side when the measurement liquid flows into the liquid junction part. When the measurement liquid contains bubbles, the bubbles are likely to stay in the opening along the flow.
Therefore, the conducting member is not covered with bubbles, and the measurement liquid penetrates into the porous member or fiber of the conducting member and comes into contact with the internal liquid to maintain the conduction between the measurement liquid and the internal liquid. Potential measurement can be performed stably.

1 is an overall schematic diagram of a measurement system according to an embodiment of the present invention. The schematic diagram of the electrode apparatus in the embodiment. The elements on larger scale of the comparative electrode in the embodiment. The schematic diagram in planar view of the opening of the comparison electrode in the embodiment. The schematic diagram which shows the pH measurement sequence in the embodiment. The schematic diagram of the electrode device in other embodiments. The elements on larger scale of the electrode device in other further embodiments. The schematic diagram of the electrode apparatus in other another embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a measurement system 100 according to this embodiment.
This measurement system 100 continuously measures the hydrogen ion concentration and the like of a chemical solution (hereinafter also referred to as “measurement solution”) used in a semiconductor manufacturing process, for example, cleaning of a wiring process, Cu plating solution, CMP (chemical mechanical polishing) and the like. An electrode device 7 for measuring the pH of the measurement liquid 9, a measurement liquid distribution mechanism 3 for allowing the measurement liquid 9 to flow through the electrode apparatus 7, and an internal liquid such as a KCl solution (invoice) The internal liquid of the reference electrode according to Item 1, which is hereinafter referred to as “second internal liquid”), the internal liquid replenishing mechanism 5, the electrode device 7, the measuring liquid circulation mechanism 3, and the internal liquid replenishing mechanism 5. And an information processing / control mechanism 19 that exchanges measurement data and command signals with them. In addition to the hydrogen ions, the measurement system 100 can also measure, for example, ion concentrations such as sodium and potassium, and gas concentrations such as carbon dioxide and oxygen (pCO2, pO2, etc.).

As shown in FIG. 2, the electrode device 7 includes the measurement electrode 4 and the comparison electrode 6 and a frame body 23 that accommodates them.
The measurement electrode 4 includes a first body 54 having a first internal liquid chamber 52 in which a predetermined internal liquid such as a pH buffer solution (hereinafter referred to as “first internal liquid”) is accommodated, and the first body 54. And an internal pole M attached so as to extend upward from the lower part of the first internal liquid chamber 52.

  The first body 54 is made of a material such as PVC (polyvinyl chloride), PP (polypropylene), PVDF (polyvinylidene fluoride), etc., and extends vertically to close the upper surface and open the lower surface. And a lid 54b that closes the lower surface opening of the main member. The first internal liquid chamber 52 formed inside the first body 54 has, for example, a constant cross-sectional shape (for example, a columnar shape) from a lower end to a predetermined height, and a cross-sectional shape increases as only the upper end portion goes upward. The cone shape is reduced.

  The inner pole M is composed of, for example, a silver / silver chloride electrode, and is attached to the lid 54b so that the lower end thereof penetrates, and the first inner liquid chamber 52 extends upward from the lid 54b. It stands up to stretch. Further, a contact is provided at the lower end of the internal pole M so that a current (voltage) signal can be taken out to the outside. The internal electrode M is not limited to the lower end portion extending from the lid body 54b, but is inclined so as to extend upward from the side surface of the main member 54a to the first internal liquid chamber 52, for example, an L shape. It may be configured as follows.

Further, in this embodiment, the electrode device 7 is provided with a tube body 58 through which the measurement liquid 9 flows.
The entire tube body 58 is formed of response glass that responds to hydrogen ions, and forms a first flow path 62 through which the measurement liquid flows. This response glass contains a predetermined amount of scandium. The shape of the tube body 58 is a capillary shape, that is, the length thereof is sufficiently long with respect to the inner diameter. For example, the inner diameter is about 0.1 mm to 2 mm, preferably about 0.5 mm to 1 mm. It is thin. In addition, the wall thickness of the tube body 58 is about 0.1 mm to 1 mm, preferably about 0.2 mm. With such a wall thickness, a responsive glass with good responsiveness is obtained. The outer diameter is about 0.3 mm to 4 mm, preferably about 1 mm to 2 mm.

The tubular body 58 is horizontally penetrated through the upper end portion of the first body 54 and is disposed so as to be immersed in the first internal liquid 50 of the first internal liquid chamber 52. More specifically, the tube body 58 is disposed above the upper end portion of the internal pole M and passes through a constant cross-sectional shape portion of the first internal liquid chamber 52.
Note that the tube 58 may be made of response glass in part of the tube 58 immersed in the first internal liquid 50.

Next, the reference electrode 6 will be described with reference to FIG.
The comparison electrode 6 has an internal liquid chamber (referred to as an internal liquid chamber of the comparison electrode according to claim 1, hereinafter referred to as “second internal liquid chamber”) in which the second internal liquid 15 is accommodated. Two bodies 42 (referring to the body of the comparison electrode according to claim 1) and an inner electrode attached so as to extend upward from the lower part of the second body 42 to the second inner liquid chamber 36. R and a replenishing port 17 that is formed in the second body 42 and communicates with the second internal liquid chamber 36 to replenish the second internal liquid 15.
The second body 42 further includes a flow path in which the measurement liquid 9 flows horizontally above the second body 42 (the measurement liquid storage portion of the comparison electrode according to claim 5, hereinafter referred to as “second flow”). And a liquid junction portion 40 disposed in the second internal liquid chamber 36 so that the second internal liquid 15 and the measurement liquid 9 are in contact with each other. The liquid junction portion 40 is formed of a conduction member 41 formed of a porous or fibrous member and an opening 45 adjacent to the conduction member 41.

  The second body 42 is formed of a material such as PVC, like the first body 54 of the measurement electrode 4, and has a rectangular tube shape that extends vertically and has an upper surface closed and a lower surface opened. It consists of a main member 42a and a lid 42b that closes the lower surface opening of the main member.

  The second internal liquid chamber 36 formed in the second body 42 has a cylindrical body formed so as to extend upward from the lower portion of the second body 42, and the upper end portion of the internal pole R The cross-sectional area from the upper end 43 of the second internal liquid chamber 36 to the predetermined distance L1 downward is smaller than the cross-sectional area below the position at the predetermined distance L1. . Further, the volume of the second internal liquid chamber 36 from the upper end 43 of the second internal liquid chamber 36 to the predetermined distance L1 is set to be smaller than the amount of the second internal liquid 15 replenished from the replenishing port 17. ing. An upper end portion 43 of the second internal liquid chamber 36 is connected to the second flow path 64. In this embodiment, the upper end portion 43 of the second internal liquid chamber has a conical shape in which the cross-sectional shape is reduced toward the upper side. However, the shape is not limited to this, and the cross-sectional shape may be constant. 9 only needs to be in contact with the second internal liquid 15.

  It should be noted that the cross-sectional area may be constant or may vary between the upper end portion 43 of the second internal liquid chamber 36 and the predetermined distance L1, and the predetermined distance L1. What is necessary is just to be formed so that it may become smaller than the cross-sectional area of the part below the position in a. Similarly, the cross-sectional area of the portion below the position at the predetermined distance L1 may be constant or may be changed.

A second flow path 64 through which the measurement liquid 9 flows is formed above the second body 42. The second flow path 64 is formed horizontally at the upper end of the second body 42.
A liquid junction portion 40 to be described later is formed so that the measurement liquid 9 flowing through the second flow path 64 and the second internal liquid 15 are in contact with each other. In this embodiment, the connection hole 49 formed below the inner peripheral surface of the second flow path 64 is connected to the upper end portion 43 of the second internal liquid chamber 36. In the present embodiment, the connection hole 49 is formed to have a substantially circular shape. However, the connection hole 49 is not limited thereto, and may be an elliptical shape or a rectangular shape.
In addition, although the 2nd flow path 64 is formed above the 2nd body 42, you may make it form below the 2nd body 42 not only in this. In this case, the second flow path 64 is connected to the lower end portion of the second internal liquid chamber 36 via the connection hole 49.
Furthermore, in this embodiment, the measurement liquid container is a flow path through which the measurement liquid 9 flows. However, the measurement liquid container is not limited to the flow path, and may be a container in which the measurement liquid 9 is stored. The second internal liquid 15 may be brought into contact with the measurement liquid 9.

  Next, the liquid junction 40 will be described with reference to FIGS. 3 and 4. The liquid junction 40 is formed of a conduction member 41 and an opening 45 adjacent to the conduction member 41. Note that the opening 45 is adjacent to the conduction member 41 when the conduction member 41 and the opening 45 are disposed so as to contact each other, for example, between the conduction member 41 and the opening 45. Even when there is something other than the conducting member 41, the opening 45 is close to a position where the bubble 47 approaching the liquid junction 40 can remain in the opening 45 without covering the conducting member 41. The case where it is arranged is also included. More preferably, this close position refers to a case where the gaps are arranged at a smaller interval than the bubbles 47 included in the measurement liquid 9.

  The conducting member 41 is formed of a porous member having a plurality of fine holes, such as ceramic, polyethylene, Teflon (registered trademark) membrane, and the like. It is arranged to touch. The conducting member 41 is a rod-like or string-like member provided so as to extend in the direction of the internal pole R, and is above the upper end of the internal pole R and is the upper end of the second internal liquid chamber 36. The portion 43 is disposed between the second internal liquid chamber 36 and the predetermined distance L1. That is, the lower end portion of the conducting member 41 may be located anywhere between the upper end portion 43 and the predetermined distance L1 of the second internal liquid chamber 36, and is above the upper end portion of the internal pole R. If it is in.

If the conducting member 41 is rod-shaped, the lower end portion thereof may be fixed to the inner wall surface of the second internal liquid chamber 36 by an adhesive or the like, or the upper end portion thereof may be The upper end portion 43 of the second internal liquid chamber 36 may be adhered, or an intermediate portion thereof may be adhered to the inner wall surface of the second internal liquid chamber 36. If the conductive member 41 has a string shape, the upper end portion thereof is fixed to the upper end portion 43 of the second internal liquid chamber 36 by an adhesive or the like, and the intermediate portion thereof is the second portion. It may be adhered to the inner wall surface of the internal liquid chamber 36.
In addition, when the said member 41 for conduction | electrical_connection is a fibrous thing, it is formed from a chemical fiber etc., for example, and has a some fine hole between fibers.

  Further, in this embodiment, the conduction member 41 is arranged so as to be located on the upstream side of the flow of the measurement liquid 9, but is not limited thereto, and is located on the downstream side of the flow of the measurement liquid 9. Alternatively, it may be arranged such that the opening 45 surrounds the conductive member 41 in a ring shape.

Further, as shown in FIG. 3A, the conduction member 41 is disposed so that the upper end portion thereof protrudes into the second flow path 64 from the opening 45. In this embodiment, the upper end portion of the conduction member 41 has a shape that becomes narrower upward, and is arranged so as to protrude to the vicinity of the center in the radial direction of the second flow path 64. The shape of the upper end portion is not limited to this, and may be a rounded shape or a substantially planar shape.
Further, as shown in FIG. 3B, the conducting member 41 may be arranged so that the upper end portion thereof is substantially flush with the opening 45. In this case, the upper end portion of the conducting member 41 is It has a substantially planar shape. The shape of the upper end portion of the conductive member 41 is not limited to this, and the upper end portion thereof may be a shape that is thin and sharp as shown in FIG. 3A, or may be a rounded shape, The upper end part should just be in the position of the substantially same surface as the opening 45. FIG.
Further, the present invention is not limited to this, and the upper end portion of the conduction member 41 may be disposed at a position lower than the opening 45 to such an extent that bubbles do not remain at the upper end portion.
In addition, as a position of the upper end part of the member 41 for conduction | electrical_connection, the direction which protrudes from the opening 45 rather than arrange | positioning on the substantially the same surface as the opening 45 mentioned above is easy and preferable.

  The opening 45 constituting the liquid junction portion 40 is connected to the second internal liquid chamber 36 and the second flow path 64 and is disposed to have a width of dimension a. The dimension a refers to the length from the conduction member 41 to the edge of the opening 45 in the opening 45. When the opening 45 is formed in a ring shape around the conduction member 41, the dimension a is the length of the ring-shaped width.

  This dimension a is set so as to be larger than the size of the fine holes of the conducting member 41. There are a plurality of fine holes having various shapes such as a substantially circular shape and a substantially rectangular shape. In general, since the surface tension acts on the bubbles and tries to maintain a spherical shape, the shape of the hole in which the bubbles are likely to stay includes a substantially circular shape, a shape close thereto, or an elliptical shape. Also, bubbles are less likely to stay in smaller holes. Therefore, the dimension a is set to be larger than the maximum diameter or major axis of the fine holes of the conductive member 41 in such a shape. The bubbles 47 remain in the gap having the dimension a, and the bubbles can be prevented from covering the conductive member 41.

Note that the dimension a is not limited to the above, and if the shape of the fine hole of the conductive member 41 is a combination of a circle or a rectangle, the diameter of the circle or the rectangle It may be set so as to be larger than the maximum length of the diagonal lines of the shape. In other words, the dimension a of the opening 45 may be set so as to be larger than the fine hole of the conductive member 41. With this setting, the bubbles 47 remain in the gap having the dimension a.
The bubbles 47 included in the measurement liquid 9 include, for example, bubbles that are generated due to pressure fluctuation when the measurement liquid 9 flows through the flow path, and bubbles that are likely to generate bubbles such as hydrogen peroxide in the measurement liquid 9. When it is contained, it is a bubble generated due to itself.

  The inner pole R is composed of, for example, a silver / silver chloride electrode, and is attached to the lid 42b so that the lower end thereof penetrates, and the second inner liquid chamber 36 is moved upward from the lid 42b. It stands up to stretch. Further, a contact is provided at the lower end of the internal pole R so that the current (voltage) signal can be taken out to the outside. Note that the lower end portion of the internal electrode R is not limited to the one extending from the lid body 42b, but is inclined so as to extend upward from the side surface of the main member 42a to the second internal liquid chamber 15 or, for example, L-shaped. It may be configured as follows.

  In the present embodiment, the replenishing port 17 is provided at a position slightly below the upper end of the internal pole R, but can be changed as appropriate. You may arrange | position in the place which can replenish the 2nd internal liquid 15 from the side, or may arrange | position so that it may be located in the center or the upper side of the internal pole R.

Next, the frame body 23 will be described with reference to FIG. The frame body 23 is formed of, for example, a resin or metal having a square box shape with an upper opening, and the measurement electrode 4 and the comparison electrode 6 are fitted into the frame body from above.
On the bottom plate of the frame body 23, contact portions 88 and 89 are arranged so that the lower end portions of the inner pole M and the inner pole R are in contact with each other.
Further, an inflow hole 63 for allowing the measurement liquid 9 to flow into the tube body 58 flowing through the first flow path 62 is formed in one side plate of the frame body 23 that contacts the measurement electrode 4, and the other side plate that contacts the comparison electrode 6 is formed. An outflow hole 65 is formed in the side plate so that the measurement liquid 9 flowing through the second flow path 64 flows out. Further, an inflow hole 67 through which the second internal liquid 15 flows into the replenishing port 17 is also formed in the other side plate.

  As described above, the electrode device 7 includes the measurement electrode 4, the comparison electrode 6, and the frame body 23. The measurement electrode 4 and the comparison electrode 6 include the inflow hole 63, the first flow path 62, and the second flow. The passage 64 and the outflow hole 65 communicate with each other, and the replenishment port 17 and the inflow hole 67 communicate with each other and are accommodated in the frame body 23. Here, the measurement electrode 4 and the comparison electrode 6 are fixed so as to be pressed against each other by, for example, screws or the like (not shown), whereby the first flow path 62 and the second flow path 64 are in close contact with each other. The measurement liquid 4 is configured not to leak. An O-ring or the like may be provided between the first flow path 62 and the second flow path 64 in order to improve adhesion. Further, in the portion of the measurement electrode 4 where the tube 58 passes through the first body 54, the tube 58 is fixed by an adhesive or the like, and the first internal liquid 50 leaks from the first internal liquid chamber 52. Not sealed.

Next, the measurement liquid circulation mechanism 3 will be described with reference to FIGS. 1 and 2.
The measurement liquid circulation mechanism 3 includes an inflow pipe 12a through which the measurement liquid 9 flows into the electrode device 7, an outflow pipe 12b through which the measurement liquid 9 flowing out through the electrode device 7 flows, and predetermined inflows of the inflow pipe 12a or the outflow pipe 12b. A distribution pump 10 is provided at a location to allow the measurement liquid 9 to flow in and out.

  The inflow pipe 12a has a distal end portion inserted into the inflow hole 63 of the frame body 23 and connected to the tube body 58 of the measurement electrode 4, so that the measurement liquid 9 is injected from the proximal end portion thereof. It is configured. The tip of the inflow tube 12a and the tube body 58 of the measurement electrode 4 are connected so as to be in close contact with, for example, an adhesive so that the measurement liquid 4 flows into the measurement electrode 4 without leaking.

  The outflow pipe 12b has a base end portion inserted into the outflow hole 65 of the frame body 23 and connected to the second flow path 64 of the comparison electrode 6, and the measurement liquid 9 is discharged from the front end portion thereof. The base end portion of the outflow pipe 12b and the second flow path 64 of the comparison electrode 6 are connected so as to be in close contact with, for example, an adhesive so that the measurement liquid 4 is discharged without leaking from the second flow path 64. Has been.

  The flow pump 10 is disposed at a predetermined location of the inflow pipe 12a or the outflow pipe 12b, for example, between the proximal end portion and the distal end portion of the outflow pipe 12b. By the operation of the flow pump 10, the measurement liquid 9 flows in the order of the inflow pipe 12a, the measurement electrode 4, and the comparison electrode 6, flows through the outflow pipe 12b, and is discharged to the outside of the measurement system 100.

  Next, the internal liquid replenishing mechanism 5 will be described with reference to FIGS. 1 and 2. The internal liquid replenishment mechanism 5 includes a container 16 in which the second internal liquid 15 is stored, a replenishment pipe 20 that connects the container 16 and the comparison electrode 6 and replenishes the comparison electrode 6 with the second internal liquid 15, and a replenishment pipe A replenishment pump 18 is provided at 20 predetermined locations and distributes the second internal liquid 15. The replenishment pipe 20 has a base end connected to the container 16 and a distal end inserted into the inflow hole 67 of the frame body 23 and connected to the replenishment port 17. The tip of the replenishment tube 20 and the replenishment port 17 of the comparison electrode 6 are connected so that the second internal liquid 15 flows into the second internal liquid chamber 36 without leaking, for example, with an adhesive or the like. Has been. An O-ring or the like may be provided between the replenishment pipe 20 and the replenishment port 17 in order to improve adhesion.

  The replenishment pump 18 is disposed between the proximal end portion and the distal end portion of the replenishment pipe 20, and the operation of the replenishment pump 18 causes the second internal liquid 15 to replenish through the replenishment pipe 20 from the container 16. The reference electrode 6 is replenished through the port 17.

  Next, the information processing / control mechanism 19 will be described with reference to FIGS. 1 and 2. The information processing / control mechanism 19 includes, for example, a potentiometer 26 that calculates the pH value of the measurement liquid 9 measured by the electrode device 7, a driver circuit 34 that includes a circuit that operates the flow pump 10 and the replenishment pump 18, A control device 29 including a computer and a display for processing information obtained from the potentiometer 26 and outputting an operation signal or the like to the driver circuit 34 is provided. In the present embodiment, the control device 29 is configured to be disposed outside the casing 2. Note that the information processing / control mechanism 19 itself may be arranged outside the casing 2.

  The potentiometer 26 is electrically connected to the internal pole M of the measurement electrode 4 and the internal pole R of the comparison electrode 6 in the electrode device 7 by the internal pole M wiring 22 and the internal pole R wiring 24 via the contact portions 88 and 89 described above. It is connected to the. Thus, the potential difference between the electrodes is measured by the potentiometer 26 based on the respective potentials detected by the internal pole M and the internal pole R. The potentiometer 26 is electrically connected to a control device 29 via an external connection terminal 28. The control device 29 calculates the pH value of the measurement liquid 9 from the output value of the potentiometer 26 by the computer, The value is displayed on the display. The calculated pH value is stored in a computer storage medium so that it can be displayed when necessary.

  The driver circuit 34 is electrically connected to the flow pump 10 and the replenishment pump 18 via the wirings 30 and 32, and the driver circuit 34 is electrically connected to the control device 29 via the external connection terminal 28. Yes. The driver circuit 34 controls the operation and stop of the flow pump 10 and the replenishment pump 18 based on signals from the computer of the control device 29, and adjusts the timing, amount, etc., of the measurement liquid 9 flowing through the electrode device 7. In addition, the replenishment amount and replenishment timing of the second internal liquid 15 are controlled so that the measurement system 100 can be continuously operated for several months, for example, about 4 to 8 months.

  Next, a measurement sequence for measuring the pH of the measurement liquid 9 using the measurement system 100 will be described with reference to FIG. A line P1 indicates ON / OFF of the operation of the flow pump 10, and the convex portion indicates ON and the concave portion indicates OFF. P2 similarly indicates on / off of the operation of the refill pump 18. The pH indicates a state where the convex portion is measuring pH, and a state where the convex portion is not performing pH measurement.

  First, after the measurement electrode 4 and the comparison electrode 6 are calibrated (not shown), the measurement is started. First, measurement 1 will be described. In measurement 1, the information processing / control mechanism 19 operates the flow pump 10 (P1) of the internal liquid replenishment mechanism 5 for a predetermined time so that the measurement liquid 9 flows through the inflow pipe 12a and the outflow pipe 12b. It flows into the measurement electrode 4 and the comparison electrode 6. The amount of measurement liquid 9 introduced at this time is, for example, about several hundred μL. After flowing the measurement liquid 9 into the measurement electrode 4 and the comparison electrode 6, the flow pump 10 is temporarily stopped. At this time, pH measurement is performed.

In this way, the steps of operation, stop, and pH measurement of the flow pump 10 in the measurement 1 are performed once, and the pH measurement is performed by repeating n measurements, for example, about 50 to 200 times continuously. After the pH measurement, the flow pump 10 is stopped by the information processing / control mechanism 19 and the replenishment pump 18 (P2) is operated for a predetermined time, so that the second internal liquid 15 such as a KCl solution is discharged from the container 16 to the second internal of the comparison electrode 6. A predetermined amount of liquid chamber 36 is replenished. The replenishment amount at this time is replenished with an amount that can replace the portion where the concentration of the second internal liquid 15 is reduced due to the flow of the measurement liquid 9 from the liquid junction 40 in the reference electrode 6, for example, about several tens of μL. Internal fluid is replenished.
Such measurement of n times and replenishment of the second internal liquid 15 are set as one measurement routine, and the measurement routine is repeated, whereby the replenishment of the second internal liquid 15 is performed periodically, and a desired number of measurements are performed. After the routine is finished, the pH measurement is finished.

  Since the measurement electrode 4 is configured as described above, the potential measurement can be performed by flowing the measurement liquid 9 through the capillary tube 58, and the amount of the measurement liquid 9 used for the measurement can be reduced. Can do. Thereby, the quantity of the chemical | medical solution discarded after a measurement can be reduced. In particular, when the potential pump is stopped by stopping the flow pump 10 to stop the flow of the measurement liquid 9, the amount of the chemical liquid to be used can be further reduced.

  Further, even when the temperature of the measurement liquid 9 is high, for example, about 50 ° C., the temperature of the measurement liquid 9 decreases while flowing in the tube body 58. Since convection does not occur, variation in measured potential due to convection can be prevented, and the accuracy of potential measurement can be improved. In addition, since the flow pump 10 is stopped, pH measurement is performed at the measurement electrode 4 and the comparison electrode 6 in a state where the flow of the measurement liquid is stopped, thereby eliminating the influence on the pH value due to the flow of the measurement liquid.

  In the present embodiment, the tube body 58 is disposed above the upper end portion of the internal pole M and passes through a constant cross-sectional shape portion of the first internal liquid chamber 52, so that the tube body is measured by pH measurement. Bubbles generated around 58 do not adhere to the tube body 58 and accumulate in the upper part of the first internal liquid chamber 52. Thereby, the fall of the measurement precision by a bubble can be prevented. In the present embodiment, the first internal liquid chamber 52 is formed in a conical shape whose cross-sectional shape decreases as the upper end of the first internal liquid chamber 52 goes upward, but the upper surface of the first internal liquid chamber 52 is not limited to this. The shape may be a hemispherical shape or the like, as long as a space in which air bubbles accumulate above the tube body 58 is formed.

  Further, since the response glass of the tube body 58 contains scandium in a predetermined amount, it has resistance to hydrofluoric acid, and even if the chemical solution to be measured is strongly acidic containing hydrofluoric acid, it is difficult to be eroded and is long. Can be used for a period.

  Since the comparison electrode 6 is configured as described above, the bubbles 47 contained in the measurement liquid 9 remain in the opening 45. Therefore, the conducting member 41 is no longer covered with bubbles, and the measurement liquid 9 penetrates into the porous or fibers of the conducting member 41 and comes into contact with the second internal liquid 15, so that the measurement liquid 9 and the second internal liquid 15 Since the continuity is maintained, the potential measurement of the measurement liquid 9 can be stably performed.

  The conductive member 41 is more preferably resistant to chemicals. If it has chemical resistance, even if the measuring solution 9 is a chemical solution having strong acidity or strong alkalinity, the conducting member 41 does not corrode and can be used for a long time.

  Further, the upper end portion of the conduction member 41 is substantially flush with the opening 45, or protrudes to the second flow path 64 side from the opening 45, or air bubbles are formed at the upper end portion of the conduction member 41. Therefore, the bubbles contained in the measurement liquid 9 can be prevented from covering the conduction member 41. Therefore, since the upper end part of the member 41 for conduction | electrical_connection can contact the measurement liquid 9, the measurement liquid 9 and the 2nd internal liquid 15 conduct | electrically_connect, and an electric potential measurement is attained.

  Further, since the conducting member 41 is provided extending in the direction of the internal pole R, even when bubbles are accumulated in the entire liquid junction 40, the lower end portion of the conducting member 41 is the second internal liquid 15. And the continuity between the measurement liquid 9 and the second internal liquid 15 can be maintained.

Further, when the lower end portion of the conduction member 41 is disposed below the upper end portion of the internal electrode R, when the second internal liquid 15 is filled from the bottom of the second internal liquid chamber 36 when the comparison electrode 6 is assembled. Then, the second internal liquid 15 carried to the upper end portion through the internal pole R reaches the lower end portion of the conduction member 41, and then reaches the inner wall surface of the second internal liquid chamber 36 through the conduction member 41. As a result, a wall of the second internal liquid 15 may be formed between the inner electrode R, the conductive member 41, and the inner wall surface. If this happens, air may accumulate inside the wall, and the portion may not be filled with the second internal liquid 15 in some cases.
However, if the conduction member 41 is disposed above the upper end portion of the internal pole R and between the upper end portion 43 of the second internal liquid chamber 36 at a predetermined distance L, such second internal liquid is provided. Thus, the second internal liquid 15 can be filled evenly in the second internal liquid chamber 36.
Note that the lower end portion of the conducting member 41 can be positioned below the upper end portion of the internal pole R. For example, the conducting member 41 has a shape along the inner wall surface of the second internal liquid chamber 36. The conductive member 41 may be configured to be at a position away from the upper end portion of the internal pole R. With such a configuration, there is no fear that a wall of the second internal liquid 15 is formed between the internal electrode R, the conductive member 41, and the inner wall surface, and the second internal liquid chamber 36 is connected to the second internal liquid chamber 36. The liquid 15 can be reliably filled.

  Further, since the comparison electrode 6 is configured as described above, the second internal liquid 15 is replenished from the replenishment port 17 below the upper end portion of the internal pole R, and the liquid around the internal pole R is supplied to the second internal The liquid 15 can be replaced, and the measurement accuracy can be maintained. In this case, since the measuring liquid 9 flows from the liquid junction 40 and the second internal liquid 15 is replaced by pushing up the thinned portion, the amount of the second internal liquid 15 corresponding to the thinned portion is replenished. What is necessary is to save and reduce the amount of replenishment.

  The position of the replenishing port 17 can be changed as appropriate. However, the replenishing port 17 may be located further downward, that is, at the lower end of the second internal liquid chamber 36. In this case, the specific gravity of the second internal liquid 15 is the measurement liquid. Even if it is smaller than 9, since it is located farthest from the liquid junction 40, the replenished second internal liquid 15 does not flow out of the liquid junction 40, and is a portion that is thinned by the inflow of the measurement liquid 9 The liquid around the inner pole R can be surely replaced with an amount corresponding to the amount of the second internal liquid 15 to be replenished.

  Further, when the specific gravity of the second internal liquid 15 is larger than the measurement liquid 9, the replenishing port 17 may be located above the upper end portion of the internal pole R. In this case, since the specific gravity of the second internal liquid 15 is larger than that of the measurement liquid 9, the second internal liquid 15 is less likely to flow out from the liquid junction 40 to the measurement liquid 9 immediately after the second internal liquid 15 is replenished. It stays around the pole R, and the concentration of the second inner liquid 15 around the inner pole R can be maintained. Further, since the second internal liquid 15 having a specific gravity greater than that of the measurement liquid 9 is replenished, the internal electrode is configured to more reliably push up the portion where the measurement liquid 9 flows from the liquid junction 40 and the second internal liquid 15 is diluted. The liquid around R can be replaced with the second internal liquid 15. Since the amount of the second internal liquid 15 to be replenished can be made an amount corresponding to the thinned portion of the measurement liquid 9 flowing in, the replenishing amount of the second internal liquid 15 can be saved and reduced.

Further, since the inner pole R is disposed so as to extend upward from the lower end portion of the second inner liquid chamber 36, the second inner liquid is supplied by the replenishment pump 18 of the inner liquid replenishing mechanism 5 as described above. 15 even if it is intermittently replenished, before the thinned portion above the second internal liquid chamber 36 reaches the internal pole R, replacement with the second internal liquid 15 is in time, Concentration can be maintained. As described above, since the second internal liquid 15 can be intermittently replenished, the amount of the second internal liquid 15 to be replenished can be reduced as compared with the case of replenishing continuously during pH measurement. The measurement system 100 can be continuously operated for a period of time, for example, about 4 to 8 months without replenishing the second internal solution 15.
Note that the second internal liquid 15 is operated so as to flow in a very small amount without completely stopping the replenishment pump 18, and a second amount of the second liquid corresponding to the thinned portion where the measurement liquid 9 flows in at a predetermined interval. Although the replenishment pump 18 can be operated to replenish the internal liquid 15, it is preferable to stop the replenishment pump 18 during pH measurement as described above.

  Furthermore, since the cross-sectional area at the predetermined distance L1 from the upper end portion 43 of the second internal liquid chamber 36 is smaller than the cross-sectional area below the position at the predetermined distance L1, this part is more than the part where the internal pole R is located. As a result, the amount of the portion in which the measurement liquid 9 flows from the liquid junction 40 and the second internal liquid 15 becomes thinner can be reduced. Accordingly, the amount of the second internal liquid 15 to be replaced is reduced, and thereby the amount of the second internal liquid 15 to be replenished can be further reduced.

The predetermined distance L1 is variously changed depending on the measurement conditions. For example, after the pH measurement is performed for a predetermined time, in the portion where the measurement liquid 9 flows from the liquid junction 40 and the second internal liquid 15 is thinned, the capacity is V2 and the upper end 43 of the second internal liquid chamber 36 is reduced. Is the distance L2. And when it is set as the capacity | capacitance V1 to the predetermined distance L1 of the 2nd internal liquid chamber 36, V1 and L1 are comprised so that the relationship of V2 <V1 and L2 <L1 may be materialized.
Based on the predetermined distance L1 thus determined and its volume V1, the replenishment amount of the second internal liquid 15 to be replenished is determined. In this case, the replenishment amount is V3, from the upper end portion 43 of the second internal liquid chamber 36. When the distance is set to L3, L2 <L3 <L1 so that the relationship of V2 <V3 <V1 is satisfied, and the portion diluted with the measurement liquid 9 can be replaced with the second internal liquid 15. become.

Furthermore, if the replenishment amount V3 is an amount that satisfies the relationship of V2 <V1 <V3, L2 <L1 <L3, and the portion diluted with the measurement liquid 9 can be sufficiently replaced with the second internal liquid 15. It becomes like this. That is, when the measurement liquid 9 is diffused from the upper end portion 43 of the second internal liquid chamber 36 to the predetermined distance L1 and the second internal liquid 15 is thinned, a larger amount than the equivalent amount is obtained. 2 Since the internal liquid 15 is replenished, the thinned portion can be reliably pushed out from the liquid junction 40 and replaced with the second internal liquid 15.
It should be noted that the volume V2 of the thinned portion and the replenishment amount V3 of the second internal liquid 15 need only satisfy the relationship of V2 <V3.

Next, an electrode device 307 will be described as another embodiment of the electrode device 7 with reference to FIG. 6 that are the same as those in FIG. 2 indicate the same or corresponding configurations as those in the above-described embodiment.
The electrode device 307 includes a measurement electrode 304 and a comparison electrode 306 as shown in FIG.
The measurement electrode 304 includes a first body 354a having a first internal liquid chamber 352 in which the first internal liquid 350 is accommodated, a sub-body 354b disposed away from the first body 354a, and a first body 354a. A connecting body 354c that connects the sub body 354b is provided. Further, the measurement electrode 304 includes an internal pole M attached so as to extend upward from the lower portion of the first body 354a through the first internal liquid chamber 352. A body 354 of the measurement electrode 304 is formed from the first body 354a, the sub body 354b, and the connection body 354c. These bodies are made of the same material as the first body 54. Similarly to the first body 54, the first body 354a includes a main member 354d and a lid 354e, and a first internal liquid chamber 352 is formed inside the main member 354d.

  The sub-body 354b is a substantially rectangular parallelepiped block, and the upper end of one side of the first body 354a and the upper end of one side of the sub-body 354b are integrally connected by a connection body 354c having a substantially rectangular parallelepiped shape. Thus, the first body 354a is spaced apart from the first body 354a. A space S1 is formed between the first body 354a and the sub body 354b that are separated from each other, with the lower part thereof opened. In the present embodiment, similarly, the sub-body 354b is connected to the connection body 354c on the other side surface of the first body 354a and is spaced apart from the first body 354a. Since the respective bodies are connected in this way, the measurement electrode 304 has the sub-body 354b via the connection body 354c on both sides with the first body 354a as the center, and is substantially T-shaped when viewed from the front. Is formed.

  Furthermore, a female screw hole 388 is formed in the sub body 354b as a connection port with the comparison electrode 306, and a male screw member 386, which is a fitting member that is engaged with the female screw hole 388 so as to be able to advance and retreat, is provided. Be placed. Further, the female screw hole 388 and the space S1 are communicated with each other through a communication hole 380.

Furthermore, in this embodiment, the measurement electrode 304 includes a tube body 358 through which the measurement liquid 9 flows.
The entire tubular body 358 is formed of response glass that responds to hydrogen ions, and forms a first flow path 362 through which the measurement liquid 9 flows. The downstream side of the first flow path 362 is the output end side of the tube body 358, and the upstream side of the first flow path 362 is the input end side of the tube body 358. The material and shape of the tube body 358 are the same as those of the tube body 58. Further, the tubular body 358 is disposed in the first body 354a in the same manner as the tubular body 58 is disposed in the first body 54.

Further, the output end side of the tube body 358 protrudes from the first body 354a and is inserted into the communication hole 380 of the sub body 354b. As a result, a part of the tube body 358 is bridged in the space S1 provided between the first body 354a and the sub body 354b, and this portion of the tube body 358 is exposed to the space S1. Become.
Further, in this embodiment, the input end side of the tube body 358 also protrudes from the first body 354a, and this input end side is formed in the sub-body 354b that is disposed apart from the other side surface of the first body 354a. The communication hole 380 is inserted.
The tube 358 may be made of response glass in a part of the tube 358 immersed in the first internal liquid 350.

  The configuration of the comparison electrode 306 is the same as that of the comparison electrode 6 in the embodiment.

  Next, a specific configuration of the electrode device 307 will be described. In the electrode device 307, the tube body 358 and the second flow path 64 of the comparison electrode 306 described above are connected by the connection pipe 382 so that the measurement liquid 9 is supplied from the measurement electrode 304 to the comparison electrode 306. It is configured.

  Specifically, the other end side of the connection pipe 382 is externally fitted to the output end side of the tube body 358, and one end side of the connection pipe 382 is tightly connected to the second flow path 64 with an adhesive or the like. A flow path through which 9 flows is formed. Furthermore, an annular member 390 for pressing the periphery of the connecting pipe 382 is provided on the outer fitting portion. More specifically, the annular member 390 is an annular member such as a ferrule having a tapered surface, and the male screw member 386 is brought into contact with the tapered surface by screwing the male screw member 386 into the female screw hole 388. Thus, the outer fitting portion of the connection pipe 382 is pressed by the ferrule, and the connection pipe 382 is fixed so as not to be detached from the pipe body 358.

  The distal end portion of the inflow pipe 12a is connected to the input end side of the pipe body 358 so that the measurement liquid 9 flows into the pipe body 358 from the inflow pipe 12a. For example, the front end of the inflow pipe 12a is externally fitted to the input end side of the tube body 358, and a fastening member is provided at that portion in the same manner as described above, so that the inflow pipe 12a is fixed so as not to be detached from the tube body 358. Yes.

  Further, in the portion where the tube body 358 penetrates the first body 354a, the tube body 358 is fixed by an adhesive or the like, and the first internal liquid 350 does not leak from the first internal liquid chamber 352. Is sealed.

  Since the electrode device 307 is configured as described above, even if the first internal liquid 350 leaks from a portion where the tube body 358 penetrates the first body 354a due to aging or the like, the output end of the tube body 358 is output. Since the transmission of the first internal liquid 350 to the comparison electrode 306 is cut off in the space exposure region provided on the side, the first internal of the measurement electrode 304 is connected to the second flow path 64 through which the measurement liquid 9 flows in the comparison electrode 306. It is possible to reliably prevent the liquid 350 from being mixed. The larger the exposed area of the space, the more reliably the transmission of the first internal liquid 350 to the comparison electrode 306 can be cut off. Therefore, it is preferable that the predetermined length of the protruding portion is longer.

In addition, since the measurement electrode 304 further includes the sub body 354b in the first body 354a, the protruding portion of the tube body 358 can be held by the sub body 354b.
Furthermore, when the sub body 354b is connected to the first body 354a by the connecting body 354c, the first body 354a, the sub body 354b, and the connecting body 354c are integrated. Therefore, the protruding portion of the tube body 358 can be more stably held by the sub body 354b, and it is possible to prevent the tube body 358 from being broken or cracked due to an unexpected bending force.

In addition, the distance between the first body 354a and the sub body 354b is determined by the width of the connecting body 354c that connects them, but the distance can be increased by increasing the width of the connecting body 354c. 1 The internal liquid 350 can be more securely blocked from the reference electrode 306. For example, when it is assumed that the leakage of the first internal liquid 350 increases, this is preferable.
In addition, since the female screw hole 388 serving as a connection port with the second flow path 64 of the comparison electrode 306 is provided on the side of the sub body 354b that contacts the comparison electrode 306, the tube 385 is connected with the above-described configuration. The tube 382 is firmly connected, and the measurement liquid 9 can be reliably supplied to the second flow path 64.

  Further, the comparison electrode 306 may be provided with the second sub-body and the second connection body so that the protruding portion of the tubular body 358 can be held. Specifically, the second sub-body of the block body is formed on the side surface of the comparison electrode 306 on the measurement electrode 304 side via the second connection body. In this way, the second sub-body is disposed away from the second body 42 to form a space similar to the space. The second sub-body holds the tubular body 358 protruding from the first body 354a, and a part of the tubular body 358 is configured to be bridged in this space.

  In such a case, since the second subbody is formed on the second body 42 of the comparison electrode 306 via the second connection body, the tube body 358 can be held without being damaged. In addition, since a part of the tube body 358 is configured to be bridged in the space formed by the second body 42 and the second connection body, the tube body 358 is provided with a space exposure region, and the first internal Transmission of the liquid 350 to the reference electrode 306 can be blocked.

Next, an electrode device 407 will be described as another further embodiment of the electrode device 7 with reference to FIG.
As shown in FIG. 7, the electrode device 407 includes a measurement electrode 404 and a comparison electrode 406.
The tube body 358 of the electrode device 307 described above is entirely formed of response glass, but the tube body 458 of the electrode device 407 is formed by connecting a plurality of tube elements. A response glass tube 458a, which is formed entirely of response glass, and an elastic tube 458b made of resin are configured as tube elements. That is, a part of the tube body 458 is made of response glass. The output end side (one end side of the elastic tube 458b) of the tube body 458 is connected to the second flow path 464 of the comparison electrode 406 so that the measurement liquid 9 is supplied from the measurement electrode 404 to the comparison electrode 406. Has been. Further, the second internal liquid chamber 415 in which the second internal liquid 415 is accommodated in the second body 442 is formed in the comparison electrode 406, and the second internal liquid 415 passes through the liquid junction portion 440 to form the second internal liquid chamber 415. The measurement liquid 9 that flows through the flow path 464 is configured to come into contact with the measurement liquid 9.

  Specifically, the other end portion of the elastic tube 458b is externally fitted to one end portion of the response glass tube 458a, and an annular fastening member 490 that is pressed from the periphery is provided in the external fitting portion. More specifically, the fastening member 490 is, for example, a conical ferrule having a tapered surface, and a male screw member 486 is formed in the first body 454a so as to abut on the tapered surface. Screwed onto. As a result, the male screw member 488 presses and fits the ferrule, the outer fitting portion of the elastic tube 458b is pressed by the ferrule, and the response glass tube 458a and the elastic tube 458b are connected.

Since the elastic tube 458b has an elastic force, when it is pressed by the ferrule, it comes into close contact with the response glass tube 458a formed of a hard response glass, whereby the response glass tube 458a and the elastic tube 458b Are connected in a liquid-tight manner.
Further, the output end side of the tube body 458 (one end side of the elastic tube 458b) is similarly connected to the second flow path 464 using the fastening member 490 or the like.

  Further, the measurement electrode 404 and the comparison electrode 406 are separated from each other to form a space S2. However, since the elastic tube 458b is soft, when the measurement electrode 404 and the comparison electrode 406 are installed in the measurement system 300, their positions are changed. Even if they are displaced, the elastic tube 458b can absorb the displacement, so that the assembly of the electrode device 407 is facilitated.

  Since the electrode device 407 is configured in this manner, the first flow channel 462 in which the first internal liquid 450 accommodated in the first internal liquid chamber 452 is the flow channel of the measurement liquid 9, similarly to the electrode device 307. Can be prevented, and the accuracy of potential measurement can be maintained.

  Even if the fastening member 490 is not used, for example, one end portion of the response glass tube 458a protruding from the first body 454a and the other end portion of the elastic tube 458b are closely connected with an adhesive or the like. You may do it. Further, the output end side of the tube body 458 may be in close contact with the second flow path 464 with an adhesive or the like.

Instead of the elastic tube 458b, the tubular body 458 may be configured such that a hard pipe-like one is connected to the response glass tube 458a to form the space S2.
Further, the measurement electrode 404 or the comparison electrode 406 may be provided with a sub-body and a connection body similar to the measurement electrode 304 to form the space S2 and hold the tube body 458.

Next, an electrode device 507 will be described as another further embodiment of the electrode device 7 with reference to FIG. 8 that are the same as those in FIGS. 6 and 7 indicate the same or corresponding configurations as those in the above-described embodiment.
As shown in FIG. 8, the electrode device 507 includes a measurement electrode 504 and a comparison electrode 506.
The measurement electrode 504 has the same configuration as the measurement electrode 304, and the measurement electrode 304 is arranged upside down. Therefore, a specific description of the configuration of the measurement electrode 504 is omitted.
The comparison electrode 506 has the same configuration as the comparison electrode 406. Therefore, a specific description of the configuration of the comparison electrode 506 is also omitted.

  Next, the electrode device 507 will be described. In this electrode device 507, the measurement electrode 504 and the comparison electrode 506 are spaced apart from each other. However, like the electrode device 307 described above, the tube 358 and the second flow path 64 of the comparison electrode 506 are connected to each other. The measurement liquid 9 is connected by a pipe 382 and supplied to the comparison electrode 506 from the measurement electrode 504. Since the connection configuration of the measurement electrode 504 and the comparison electrode 506 in the connection pipe 382 is the same as that in the measurement electrode 404 and the comparison electrode 406, a specific description thereof is omitted.

  Since the electrode device 507 is configured in this way, bubbles generated around the tube 358 disposed below the first internal liquid chamber 352 of the measurement electrode 504 due to pH measurement are generated in the first internal liquid chamber 352. To the upper side (in the direction of the lid 354e). As a result, the bubbles do not adhere to the tube 358, and a reduction in measurement accuracy due to the bubbles can be prevented.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, when it is desired to measure not only the hydrogen ion concentration but also the concentration of sodium ions, potassium ions, etc., for example, a plurality of measurement electrodes may be provided in parallel according to the type of ions to be measured. Then, the measurement liquids flowing out from the measurement electrodes may be joined together so that the reference electrode is shared. Alternatively, a plurality of measurement electrodes are provided in series so that hydrogen ions, sodium ions, potassium ions, etc. are measured in order, and a comparison electrode is also provided in series, so that the comparison electrodes are shared. Also good. If it is such, a measurement system can be made compact and the density | concentration of several ion etc. can be measured simultaneously.

100 ... Measuring system 4, 304, 404, 504 ... Measuring electrode 6, 306, 406, 506 ... Comparative electrode 7, 307, 407, 507 ... Electrode device 10 ... Distribution pump 17. .... Replenishment port 18 ... refill pump 36 ... second internal liquid chamber 40 ... liquid junction 41 ... conducting member 42 ... second body 45 ... opening 52 ... first 1 internal liquid chamber 54... First body

Claims (6)

A body including an internal liquid chamber in which the internal liquid is stored, and a liquid junction disposed in the internal liquid chamber so that the internal liquid and the measurement liquid to be measured are in contact with each other;
An internal electrode disposed in the internal liquid chamber,
The liquid junction is formed from a conductive member formed of a porous or fibrous member, and an opening formed in the body so that the internal liquid and the measurement liquid are in contact with each other. And
A comparative electrode, wherein the opening is formed so as to be adjacent to the conducting member.   2. The comparative electrode according to claim 1, wherein the conductive member is arranged such that the size of the opening is larger than the size of the fine hole of the conductive member.   In the conducting member, the end portion that comes into contact with the measurement liquid is disposed so as to be substantially flush with the opening or so as to protrude to the measurement liquid side from the opening. The reference electrode according to claim 1 or 2.   The comparative electrode according to claim 1, wherein the conducting member is provided so as to extend in the inner pole direction. When the measurement liquid is further accommodated in the measurement liquid container , and the measurement liquid flows in one direction in the measurement liquid container , the opening is downstream of the flow of the measurement liquid from the conduction member. The comparative electrode according to claim 1, wherein the comparative electrode is disposed on a side. The measurement liquid storage unit is located above the internal liquid chamber, is above the upper end of the internal electrode, and the cross-sectional area of the internal liquid chamber from the upper end of the internal liquid chamber to a predetermined distance is the predetermined area. The internal liquid chamber is formed so as to be smaller than the cross-sectional area below the position in the distance,
The comparative electrode according to claim 5, wherein the conducting member is disposed between the predetermined distance from an upper end portion of the internal liquid chamber.