JP2008164398A - pH-MEASURING DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pH-measuring device capable of accurately determining the pH value of a liquid to be inspected, by preventing the influence of temperature difference of replaced liquid to be inspected and influence due to leakage of potassium chloride solution from salt bridge. <P>SOLUTION: The heat capacity of a pH standard liquid storage cell 11 is set equal to that of liquid to be inspected storage cell 21, the heat capacity of a primary-side communication section 12 is set equal to that of a secondary-side communication section 22; and the potential difference between two cells 11b and 11c for primary-side measurement, measured by primary-side measuring electrodes 4a and 4b, is used for correcting the pH value of the liquid Q to be inspected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention measures the pH value of a secondary standard solution adjusted in accordance with an official measuring method according to regulations such as the measurement method and JIS, etc., with high accuracy, in particular for measuring an accurate pH value of a test solution. The present invention relates to a pH measuring device.

  The pH measurement by the glass electrode method is easy to operate as compared with the pH measurement by the hydrogen electrode method, and has a relatively high accuracy and reproducibility. This pH measurement by the glass electrode method is generally performed by a beaker measurement or a measurement method using a flow cell. However, for example, in the beaker measurement, since the measurement is performed in a state where the reference electrode and the pH electrode are immersed in the test solution in one beaker, (a) due to leakage of the internal solution (potassium chloride solution) of the comparison electrode, The pH value of the test solution itself fluctuates. (B) The carbon dioxide gas in the atmosphere dissolves in the test solution by stirring or the like, and the pH value of the test solution itself fluctuates. (C) Reference electrode reference There is a problem that the potential changes due to the stirring and flow effects of the test solution. For this reason, the pH value of the primary standard solution (which is an aqueous solution having a constant concentration obtained by dissolving a reagent whose purity has been determined by the national government, and the potential indicated by this aqueous solution serves as a reference for the pH value), and the secondary standard solution PH measurement that requires at least a high measurement accuracy of about 1/1000 pH, such as a pH value (adjusted by a company or the like so as to show the same pH value as that of the primary standard solution) Difficult to do. This problem also occurs in the fluidized cell method.

Therefore, the conventional glass electrode method pH measuring apparatus is configured separately from the reference electrode tank and the test liquid tank, and has the same composition as the test liquid in the salt bridge that electrically connects the liquid in each tank. The liquid is used. As a result, the reference potential of the comparison electrode is prevented from changing due to the stirring or flow effect of the test solution, and the internal solution of the comparison electrode is prevented from leaking into the test solution. In addition, the lid is completely shielded from the outside air by the lid, thereby preventing pH change due to dissolution of carbon dioxide in the atmosphere (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 61-30853

  However, when measuring both the pH value of the primary standard solution and the pH value of the secondary standard solution or measuring the pH values of a plurality of secondary standard solutions with the conventional pH measuring apparatus described above. The liquid used for the test solution tank and the salt bridge must be replaced. And if there is a temperature difference between the liquids before and after replacement, a measurement electrode having a temperature characteristic (for example, an electromotive force changes depending on the temperature) causes an error in the pH value due to the temperature change, so that high-precision measurement is performed. I can't.

  Therefore, the solution used for the salt bridge is a potassium chloride solution so that it does not need to be replaced, and only the test solution is replaced. It seems that it may be sufficient to wait until it disappears before measuring. However, if the time until the temperature difference disappears becomes long, the amount of the potassium chloride solution diffusing from the salt bridge increases, the pH value of the test solution fluctuates, and a highly accurate measurement result cannot be obtained.

  The present invention has been made paying attention to such a problem, the main purpose is to prevent the influence of the temperature difference of the test liquid to be replaced and the influence of leakage of the potassium chloride solution from the salt bridge, An object of the present invention is to provide a pH measuring device that can accurately determine the pH value of a test solution.

That is, the pH measurement device according to the present invention is provided between three pH standard solution storage cells that store pH standard solutions and adjacent pH standard solution storage cells, and is stored in each pH standard solution storage cell. Two primary side communication parts for communicating, two test liquid storage cells for storing the test liquid,
A secondary-side connecting portion that is provided between the two test solution storage cells and communicates with the test solution stored in each test solution storage cell, an electrolyte solution storage cell that stores an electrolyte solution, and the electrolyte solution The electrolyte solution in the storage cell, the pH standard solution in the cell used as the primary salt bridge cell in the pH standard solution storage cell, and the secondary salt bridge cell in the test solution storage cell A primary side salt bridge and a secondary side salt bridge that are electrically connected to a test solution in the cell, respectively, and a pH standard solution in two cells used as a primary side measurement cell among the pH standard solution containing cells. A measurement electrode for measuring the potential for determining the pH value of the pH standard solution by immersing each, and a reference electrode for immersing in the electrolyte solution to give a reference potential to the measurement electrode, the pH standard solution Storage cell and test liquid storage And the primary side connecting part and the secondary side connecting part are configured to have the same heat capacity, and the potential difference between the two primary side measurement cells measured by the measurement electrode is determined. It is used for correcting the pH value of the test solution.

  Here, in order to make the heat capacity of the pH standard solution storage cell and the test solution storage cell equal, it can be realized, for example, by making the shape and material of each cell the same. Moreover, in order to prevent the pH value of the pH standard solution and the pH value of the test solution from being affected by the influence of carbon dioxide in the air, the pH standard solution storage cell and the test solution storage cell are It is desirable to use a sealed type.

  If this is the case, on the secondary side, the secondary side salt bridge cell is connected to the secondary side salt bridge cell and the secondary side measurement cell by the secondary side connecting section. It is possible to prevent the electrolyte solution leaking inside from further leaking to the secondary side measurement cell. For this reason, even if there is a temperature difference between the test liquid after replacement and the test liquid before replacement, and it takes time to eliminate the temperature difference, the electrolyte that has flowed into the secondary salt bridge cell The solution can suitably prevent the pH value of the test solution in the secondary measurement cell from fluctuating.

  On the primary side, the primary side salt bridge cell and one of the primary side measurement cells (hereinafter referred to as the salt bridge side) are connected by the primary side linking section, so the same as in the secondary side It is possible to suitably prevent the pH value of the pH standard solution in the primary-side measurement cell on the salt bridge side from being fluctuated by the electrolyte solution flowing into the primary-side salt bridge cell.

  Thus, when the test solution is exchanged, even if there is a temperature difference between the test solutions before and after the exchange, the pH values of the pH standard solution and the test solution measured on the primary side and the secondary side respectively vary. Since this can be suitably prevented, the pH of the test solution can be measured with high accuracy.

  Next, considering the case where the electrolyte solution leaks into the secondary side measurement cell due to the reason that it takes time to eliminate the temperature difference, in this case, the primary side measurement cell and the secondary side on the salt bridge side Since the heat capacity of the measurement cell is equal and the heat capacity of the primary side communication part and the secondary side communication part are equal, the electrolyte solution is similarly applied to the primary side measurement cell of the salt bridge side. Leaks. At this time, the amount of change in the pH value of the test solution generated in the secondary measurement cell and the amount of change in the pH value of the pH standard solution generated in the primary measurement cell on the salt bridge side should be the same. It becomes equal by having.

  And even if such a leak exists in the primary side measurement cell of the salt bridge side, the other of the primary side measurement cell and the primary side measurement cell (hereinafter referred to as the anti-salt bridge side) Since the electrolyte solution leaked in the primary-side measurement cell on the salt bridge side can be prevented from further leaking to the primary-side measurement cell on the anti-salt bridge side. become. From this, the pH value of the pH standard solution measured in the primary-side measurement cell on the anti-salt bridge side is higher in reliability than the pH value of the pH standard solution measured in the primary-side measurement cell on the salt bridge side. Can be treated as.

  As a result, the pH value of the test solution can be obtained with high accuracy by using the potential difference between the two primary measurement cells measured with the measurement electrode for correcting the pH value of the test solution.

  As a desirable mode of the present invention, the primary measurement electrode immersed in the primary measurement cell adjacent to the primary salt bridge cell among the two measurement electrodes is accommodated from the primary measurement cell. Among the cells, there is a mobile type that is also used as a secondary measurement electrode that moves to a cell used as a secondary measurement cell and measures a potential for determining the pH value of the test solution.

  If this is the case, it is possible to prevent a measurement error from occurring due to a calibration error between the primary side measurement electrode and the secondary side measurement electrode, and it is possible to save the labor of those calibrations and the number of measurement electrodes. The cost of the entire apparatus can be reduced because only two are required.

  In general, the liquid junction of the measurement electrode is often provided on the lower end side of the measurement electrode. Therefore, if the primary side communication part is provided immediately below the liquid surface of the pH standard solution accommodated in the pH standard solution storage cell, the distance between the liquid junction part of the primary side measurement electrode and the primary side communication part is increased. The primary measurement electrode can be made less susceptible to electrolyte solution leakage. Similarly, in order to make it less susceptible to the leakage of the electrolyte solution in the secondary side measurement electrode, the secondary side communication part is provided immediately below the liquid surface of the test liquid stored in the test liquid storage cell. It is desirable.

  As described above, according to the pH measurement apparatus of the present invention, while preventing the influence of the temperature difference of the test liquid to be replaced or the leakage of the electrolyte solution from the salt bridge, it is based on the pH value of the pH standard solution. The pH value of the test solution can be determined with high accuracy.

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

  As shown in FIGS. 1 and 2, the pH measurement apparatus A according to the present embodiment includes three pH standard solution storage cells 11a, 11b, and 11c, two primary side communication parts 12a and 12b, and two test objects. Liquid storage cells 21a, 21b, secondary side communication section 22, electrolyte solution storage cell 3, primary side salt bridge 13 and secondary side salt bridge 23, two measurement electrodes 4a, 4b, and comparison electrode 5 The thermostat 6 and the pH value calculating means 7 are provided. In this embodiment, the pH standard solution P accommodated in the pH standard solution containing cells 11a to 11c is a primary standard solution, specifically, “a solution whose purity is determined by the country is dissolved into a constant concentration aqueous solution, On the other hand, as a test liquid Q to be stored in the test liquid storage cells 21a and 21b, a secondary standard solution, specifically, “primary standard solution By using `` adjusted by a business operator etc. to show the same pH value as the pH value '', the pH value of the secondary standard solution can be obtained accurately based on the pH value of the primary standard solution. Yes. For convenience of drawing, in FIG. 1, the connecting portions 12 a, 12 b and 22, the salt bridges 13 and 23, etc. are omitted as appropriate. Hereinafter, each part is demonstrated concretely.

The pH standard solution storage cells 11a, 11b, and 11c (hereinafter sometimes collectively referred to as the pH standard solution storage cell 11) have a bottomed cylindrical shape formed of a material (for example, glass) that is not affected by the liquid stored therein. The primary standard solution is accommodated inside as the pH standard solution P. In this embodiment, among these three pH standard solution storage cells 11, one cell 11a is used as a primary salt bridge cell, and the other two cells 11b and 11c are used as primary measurement cells. I am doing so. In addition, in this embodiment, a lid (not shown) is provided at the opening of the pH standard solution storage cell 11 so that the inside can be sealed with an inert gas (for example, N ₂ gas). . Furthermore, although the capacity | capacitance of the pH standard solution P accommodated in each pH standard solution accommodation cell 11 is 20 ml, respectively, it can change suitably according to an embodiment.

  The primary side communication parts 12a and 12b (hereinafter, may be collectively referred to as the primary side communication part 12) have a cylindrical shape formed of a material (for example, glass) that is not affected by the liquid accommodated therein, The pH standard solution P is provided between the adjacent pH standard solution storage cells 11 and communicates with the pH standard solution P stored in each pH standard solution storage cell 11. In this embodiment, this primary side communication part 12 is provided just under the liquid level of pH standard solution P accommodated in pH standard solution accommodation cell 11 (not shown).

The test liquid storage cells 21a and 21b (hereinafter sometimes collectively referred to as the test liquid storage cell 21) have a bottomed cylindrical shape made of a material that is not affected by the liquid stored therein, and The next standard solution is accommodated inside as the test solution Q. In the present embodiment, among these three test solution storage cells 21, one cell 21a is used as a secondary salt bridge cell, and the other cell 21b is used as a secondary measurement cell. ing. Further, in this embodiment, the cell shape and material of the test solution storage cell 21 are the same as those of the pH standard solution storage cell 11, so that the heat capacity of the test solution storage cell 21 and the pH standard solution storage cell are as follows. 11 heat capacity is made equal. In addition, in this embodiment, similarly to the pH standard solution storage cell 11, a lid (not shown) is provided at the opening of the test solution storage cell 21, and an inert gas (for example, N ₂ gas) is provided inside. It can be filled and sealed. Furthermore, although the capacity | capacitance of the test liquid Q accommodated in each test liquid accommodation cell 21 is 20 ml, respectively, it can change suitably according to an embodiment.

  The secondary side connecting portion 22 has a cylindrical shape made of a material that is not affected by the liquid stored therein, and is provided between the two test liquid storage cells 21. The test liquid Q contained in the container is communicated. And in this embodiment, by making the shape and material of this secondary side communication part 22 the same as that of the primary side communication part 12, the heat capacity of the secondary side communication part 22 and the heat capacity of the primary side communication part 12 Are made equal. In addition, in the present embodiment, the secondary side connecting portion 22 is provided directly below the liquid surface of the test liquid Q stored in the test liquid storage cell 21 (not shown).

The electrolyte solution storage cell 3 has a bottomed cylindrical shape formed of a material (for example, glass) that is not affected by the liquid stored therein, and stores the electrolyte solution R as an internal liquid. In the present embodiment, a potassium chloride solution is used as the electrolyte solution R, but the present invention is not limited to this, and “a concentrated solution of a salt related to a combination in which cation and anion mobility are substantially equal” may be used. it can. In addition, in this embodiment, similarly to the pH standard solution storage cell 11 and the like, a lid is provided at the opening of the electrolyte solution storage cell 3 and the inside can be sealed with an inert gas (for example, N ₂ gas). I am doing so.

  The primary side salt bridge 13 has an inverted U shape formed of a material (for example, glass) that is not affected by the electrolyte solution R accommodated therein, and the primary salt bridge 13 includes the electrolyte solution R in the electrolyte solution accommodation cell 3 and the primary solution. The pH standard solution P in the side salt bridge cell 11a is electrically connected.

  The secondary salt bridge 23 has an inverted U shape formed of a material (for example, glass) that is not affected by the electrolyte solution R accommodated therein, and the electrolyte solution R in the electrolyte solution accommodation cell 3; The test solution Q in the secondary salt bridge cell 21a is electrically connected. In this embodiment, the shape and material of the secondary side salt bridge 23 are the same as those of the primary side salt bridge 13, so that the heat capacity of the secondary side salt bridge 23 and the heat capacity of the primary side salt bridge 13 are as follows. Are made equal.

  The measurement electrodes 4a and 4b (hereinafter sometimes collectively referred to as the measurement electrode 4) include a pH-responsive electrode film, a highly insulating support tube that supports the electrode film, a glass electrode internal liquid (in this embodiment, A potassium chloride solution), an internal electrode (in this embodiment, silver chloride is used), a lead wire, a glass electrode terminal, and the like. In the present embodiment, the measurement electrodes 4a and 4b are both used as the primary measurement electrodes. Specifically, the measurement electrodes 4a and 4b are simultaneously immersed in the pH standard solution P in the primary measurement cells 11b and 11c, respectively, and the potential for determining the pH value of the pH standard solution P is measured. Used for. Of the two measurement electrodes 4a and 4b, the measurement electrode 4a is also used as a secondary measurement electrode. Specifically, after measuring the potential for determining the pH value of the pH standard solution P, the measurement electrode 4a moves immediately and is immersed in the test solution Q in the secondary measurement cell 21b. This is used to measure the potential for determining the pH value of the test solution Q.

  The reference electrode 5 includes a liquid junction, an internal liquid, a replenishing port, a comparative electrode support tube, a comparative electrode internal liquid (a potassium chloride solution is used in the present embodiment), an internal electrode (silver chloride in the present embodiment), not shown. And electrode lead wires. In the present embodiment, the reference electrode 5 is immersed in the electrolyte solution R in the electrolyte solution storage cell 3 so that a reference potential is applied to each measurement electrode 4. The reference electrode 5 is kept immersed in the electrolyte solution R in the electrolyte solution storage cell 3 and replaced with the pH standard solution P or the test solution Q in order to ensure the stability of the diffusion potential when the solution is replaced. The configuration is not allowed.

  The thermostatic chamber 6 controls the temperature of the three pH standard solution storage cells 11, the two primary side communication parts 12, and the electrolyte solution storage cell 3 with a heater (not shown) and a temperature sensor T in the bath. The liquid P, Q, R stored in each cell 11, 12, 3 can be kept at a predetermined temperature by holding it in the constant temperature water 61. is there.

  Although not shown in detail, the pH value calculation means 7 includes a pH meter 71 connected to the measurement electrodes 4a and 4b and the comparison electrode 5 and having a resolution of 1/1000 pH or less, a memory 721 and a calculation unit 722 (not shown), and the like. The information processing apparatus 72 is provided. Among these, the calculation unit 722 calculates the pH value of the test solution Q from the potential difference between the pH standard solution P and the test solution Q measured using the measurement electrodes 4 a and 4 b and the comparison electrode 5. In the present embodiment, the potential difference when the pH standard solutions P stored in the pH standard solution storage cell 11 are measured is used for correcting the pH value of the test solution Q.

  A method for measuring the pH value of the test solution Q using the pH measuring apparatus A configured as described above will be described.

  (1) Measurement of pH standard solution

  First, as shown in FIG. 3, the measurement electrodes 4a and 4b are simultaneously immersed in the pH standard solution P in the primary measurement cells 11b and 11c, respectively, and the reference electrode 5 is placed in the electrolyte solution containing cell 3 as an electrolyte. Immerse in solution R. Then, the potential of the measuring electrodes 4a and 4b with respect to the reference electrode 5 is measured by the pH meter 71, and the potential values of the pH standard solution P measured by these measuring electrodes 4a and 4b (referred to as E1 and E2, respectively). Is temporarily stored in the memory 721.

  (2) Measurement of test liquid

  Next, as shown in FIG. 4, the measurement electrode 4a is extracted from the pH standard solution storage cell 11 and immersed in the test solution Q in the secondary-side measurement cell 21b. Then, the potential of the measurement electrode 4 a with respect to the comparison electrode 5 is measured by the pH meter 71, and the value of the potential of the test solution Q (referred to as E 3) measured by the measurement electrode 4 a is temporarily stored in the memory 721.

  (3) Calculation of pH value of test solution

  Then, based on the potential value of the pH standard solution P temporarily stored in the memory 721 and the potential value of the test solution Q, the calculation unit 722 of the pH value calculation means 7 determines the pH value of the test solution Q. Is calculated. At this time, the potential values of the pH standard solution P measured by the measurement electrodes 4a and 4b are compared with each other. If they are not equal, the difference between these values is used for correcting the pH value of the test solution Q.

  Specifically, for example, due to leakage of the electrolyte solution R from the electrolyte solution storage cell 3, the potential equal to the pH standard solution P in the primary measurement cell 11b and the test solution Q in the secondary measurement cell 21b. Suppose there is a change. As shown in FIGS. 3 and 4, when the potential of the pH standard solution P measured by the measurement electrodes 4a and 4b is E1 and E2, and the potential of the test solution Q measured by the measurement electrode 4a is E3, 5. As shown in FIG. 6, by correcting the difference ΔE (= E1−E2) from E3, the pH value of the test solution Q can be obtained with high accuracy.

  (4) When measuring other test liquids

  When measuring another test liquid Q continuously, the test liquid Q stored in the test liquid storage cell 21 is replaced, and the measurement of the test liquid Q exchanged in the order of (2) and (3) above is performed. The pH value is calculated.

  According to the pH measuring apparatus A according to the present embodiment configured as described above, on the secondary side, the secondary side communication unit 22 establishes a gap between the secondary side salt bridge cell 21a and the secondary side measurement cell 21b. Since the connection is made, the electrolyte solution R leaking into the secondary salt bridge cell 21a can be prevented from further leaking into the secondary measurement cell 21b. For this reason, even if there is a temperature difference between the test liquid Q after replacement and the test liquid Q before replacement, and it takes time to eliminate the temperature difference, the secondary salt bridge cell 21a has a temperature difference. It is possible to suitably prevent the pH value of the test solution Q in the secondary measurement cell 21b from being changed by the electrolyte solution R that has flowed out.

  On the primary side, the primary side salt bridge cell 11a and the primary side measurement cell 11b on the salt bridge side are connected by the primary side connecting portion 12a, so that the primary side salt is the same as in the secondary side. It is possible to suitably prevent the pH value of the pH standard solution P in the primary measurement cell 11b on the salt bridge side from being changed by the electrolyte solution R flowing out into the bridge cell 11a.

  Thus, when the test liquid Q is replaced, even if there is a temperature difference between the test liquid Q before and after the replacement, the pH of the pH standard solution P and the test liquid Q that are measured on the primary side and the secondary side, respectively. Since the fluctuation of the value can be suitably prevented, the pH of the test liquid Q can be measured with high accuracy.

  Next, considering the case where the electrolyte solution R leaks into the secondary measurement cell 21b for reasons such as it takes time to eliminate the temperature difference, in this case, the salt bridge side primary measurement cell 11b and Since the heat capacity of the secondary side measurement cell 21b is configured to be equal and the heat capacity of the primary side communication unit 12a and the secondary side communication unit 22 is configured to be equal, the primary measurement cell 11b on the salt bridge side Similarly, the electrolyte solution R leaks. At this time, the amount of change in the pH value of the test solution Q generated in the secondary-side measurement cell 21b and the amount of change in the pH value of the pH standard solution P generated in the primary-side measurement cell 11b on the salt bridge are shapes. It becomes equal by making etc. the same.

  And even if such a leak exists in the primary side measurement cell 11b on the salt bridge side, the primary side measurement cell 11b on the salt bridge side and the primary side measurement cell 11c on the anti-salt bridge side are connected to the primary side. Since it is connected by the connecting portion 12b, it is possible to prevent the electrolyte solution R leaking into the primary-side measurement cell 11b on the salt bridge side from further leaking to the primary-side measurement cell 11c on the anti-salt bridge side. become. Thus, the pH value of the pH standard solution P measured in the primary side measurement cell 11c on the anti-salt bridge side is more reliable than the pH value of the pH standard solution P measured in the salt side primary measurement cell 11b. It can be handled as a highly specific value.

  As a result, by using the potential difference between the two primary measurement cells 11b and 11c measured with the primary measurement electrode to correct the pH value of the test solution Q, the pH value of the test solution Q can be accurately determined. It will be obtained.

  In addition, since the pH standard solution storage cell 11 and the test solution storage cell 21 are each filled with an inert gas so that they can be sealed, the liquid stored in each cell contains carbon dioxide gas in the air. It is possible to prevent such a problem that the pH value of each liquid fluctuates due to absorption.

  That is, the pH measurement device A that can accurately determine the pH value of the test solution Q by preventing the influence of the temperature difference of the test solution Q to be replaced and the effect of leakage of the potassium chloride solution from the salt bridge is provided. can do.

  The present invention is not limited to the above embodiment.

  For example, the shapes and materials of the pH standard solution storage cell 11 and the test solution storage cell 21 can be appropriately changed only when the heat capacities of the respective cells are the same. Further, the number of cells can be changed as appropriate. The shapes and materials of the primary side communication unit 12 and the secondary side communication unit 22 can be changed as appropriate only when the heat capacities of the respective communication units are the same.

  The pH standard solution stored in the pH standard solution storage cell 11 is not limited to the primary standard solution described above. The test liquid Q stored in the test liquid storage cell 21 is not limited to the secondary standard solution described above.

  As shown in FIG. 2 and the like, when the three pH standard solution storage cells 11, the two test solution storage cells 21, and the electrolyte solution storage cell 3 are viewed in plan, they are arranged in a lattice shape. However, the arrangement mode is not limited to this embodiment.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 is an overall schematic diagram showing a pH measurement apparatus according to an embodiment of the present invention. The figure which shows arrangement | positioning aspects, such as a pH standard solution accommodation cell in the same embodiment. The figure for demonstrating the measuring method with the pH measuring apparatus in the embodiment. The figure for demonstrating the measuring method with the pH measuring apparatus in the embodiment. The figure for demonstrating correction | amendment of the pH value of the test liquid in the embodiment (when the electric potential of a test liquid is higher than the electric potential of pH standard solution). The figure for demonstrating correction | amendment of the pH value of the test liquid in the same embodiment (when the electric potential of a test liquid is lower than the electric potential of a pH standard solution).

Explanation of symbols

P ... pH standard solution Q ... Test solution R ... Electrolyte solution 3 ... Electrolyte solution storage cell 4 ... Measurement electrodes 4a, 4b ... Primary measurement electrode 4a ················· Secondary electrode 5 ·············· Comparative electrode 11 ············· pH standard solution Containment cell 11a ············· pH standard solution storage cell (cell for primary side salt bridge)
11b, 11c ·········· pH standard solution storage cell (cell for primary side measurement)
12 (12a, 12b) ··· Primary side communication section 13 ············· Primary side salt bridge 21 ······················・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Test solution storage cell (secondary salt bridge cell)
21b ···················· Liquid sample storage cell (secondary side measurement cell)
22 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Secondary side communication part 23 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Secondary side salt bridge

Claims (4)

three pH standard solution storage cells for storing pH standard solutions;
Two primary side communication units that are provided between adjacent pH standard solution storage cells and communicate with pH standard solutions stored in each pH standard solution storage cell;
Two test liquid storage cells for storing the test liquid;
A secondary side communication unit that is provided between these two test liquid storage cells and connects the test liquid stored in each test liquid storage cell;
An electrolyte solution containing cell containing an electrolyte solution;
The electrolyte solution in the electrolyte solution storage cell, the pH standard solution in the cell used as the primary salt bridge cell in the pH standard solution storage cell, and the secondary salt bridge in the test solution storage cell A primary side salt bridge and a secondary side salt bridge that electrically connect the test solution in the cell used as a cell, respectively;
A measuring electrode for measuring the potential for determining the pH value of the pH standard solution by immersing each in a pH standard solution in two cells used as a primary side measurement cell among the pH standard solution containing cells;
A reference electrode that is immersed in the electrolyte solution and gives a reference potential to the measurement electrode;
While configuring the heat capacity of the pH standard solution storage cell and the test solution storage cell equally, and configuring the heat capacity of the primary side communication unit and the secondary side communication unit equally,
A pH measurement device that uses a potential difference between two primary measurement cells measured with the measurement electrode to correct the pH value of the test solution.   Of the two measurement electrodes, the primary side measurement electrode immersed in the primary side measurement cell adjacent to the primary side salt bridge cell is for measuring the secondary side of the test solution storage cell from the primary side measurement cell. The pH measuring device according to claim 1, wherein the pH measuring device is of a mobile type that is also used as a secondary measurement electrode that moves to a cell used as a cell and measures a potential for determining a pH value of the test solution.   The pH measuring device according to claim 1 or 2, wherein the primary side communication part is provided immediately below the surface of the pH standard solution stored in the pH standard solution storage cell.   The pH measuring device according to any one of claims 1 to 3, wherein the secondary side communication section is provided immediately below the liquid surface of the test liquid stored in the test liquid storage cell.