JP2010151749A - Automatic titrator and ph calibration method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic titrator hardly generating an error during titration of sample liquid after water washing, even if the number of times of water washing is small, and to provide its pH calibration method. <P>SOLUTION: In this method, an acid side calibration process is performed, which includes: a storage step B1 for introducing acid standard solution into a titration vessel, storing pH of the acid standard solution and a potential of a pH electrode, and then discharging the solution; the first cleaning step B2 performed once or more times for introducing cleaning water into the titration vessel after the storage step B1, and then discharging the solution; a neutralization step B3 for introducing the cleaning water into the titration vessel after the first cleaning step B2, neutralizing the cleaning water with titration liquid, and then discharging the solution; and the second cleaning step B4 performed once or more times for introducing the cleaning water into the titration vessel after the neutralization step B3, and then discharging the solution. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an automatic titration apparatus that can be used for food acidity, salinity measurement, plating solution concentration control, and the like, and a pH calibration method thereof.

Titration, in which a titrant is added to a sample solution little by little and reacted with the substance to be measured in the sample solution, is an effective and versatile analytical method for measuring the concentration of chemical components. It is used in various industrial fields such as salinity measurement and plating solution concentration management (for example, Patent Document 1).
In particular, neutralization titration type automatic titration apparatuses that add an acidic or basic titrant to a sample solution are most widely used.
In the neutralization titration method, pH during titration is detected by a pH electrode, and this is used as a titration index value to automatically determine the end point. Since the pH electrode requires periodic standard solution calibration, calibration work using the pH standard solution is also performed in the automatic titration apparatus. In the calibration work, it is necessary to introduce a pH standard solution into a titration container for titration. Therefore, at the end of the calibration operation, the pH standard solution is drained from the titration container, and the inside is washed with water (for example, Patent Document 2).
JP-A-3-137562 JP-A-6-265510

However, even if water washing is performed, if even a small amount of the pH standard solution remains in the titration container, an error occurs during the subsequent titration of the sample solution. In particular, as the pH standard solution, since a solution having a normal buffering action is used, the influence due to the residual was large.
Therefore, at the end of the calibration work, it is necessary to repeat the water cleaning many times, the consumption of water used for the cleaning is large, and the time required for the cleaning is also long.
The present invention has been made in view of the above circumstances, and provides an automatic titration apparatus that is less likely to cause an error during subsequent titration of a sample liquid even when the number of water washings is small, and a pH calibration method thereof. This is the issue.

In order to achieve the above object, the present invention employs the following configuration.
[1] A pH calibration method of an automatic titration apparatus that titrates a sample solution with a basic titrant while detecting pH with a pH electrode inserted in the titration vessel, and an acid side calibration in which calibration is performed with an acidic standard solution The acidic calibration process includes a storage step of introducing an acidic standard solution into the titration vessel, storing the pH of the acidic standard solution and the potential of the pH electrode, and then draining the solution, and a titration vessel after the storage step. One or more first washing steps for introducing and draining the washing water, and neutralization for introducing the washing water into the titration vessel after the first washing step, neutralizing the washing water with the titration liquid, and then draining it. A pH calibration method for an automatic titration apparatus, comprising: a step; and one or more second washing steps of introducing and draining washing water into the titration container after the neutralization step.
[2] The pH calibration method for an automatic titration apparatus according to [1], wherein the acidic side calibration step is the final step in the total pH calibration step.

[3] A pH calibration method for an automatic titration apparatus that titrates a sample solution with an acidic titrant while detecting the pH with a pH electrode inserted in the titration vessel, the basic side calibrating with a basic standard solution A calibration step, wherein the basic side calibration step introduces a basic standard solution into the titration vessel, stores the pH of the basic standard solution and the potential of the pH electrode, and then drains, and after the storage step One or more first washing steps for introducing and draining the washing water into the titration container, and introducing the washing water into the titration container after the first washing step, neutralizing the washing water with the titration liquid and then discharging A pH calibration method for an automatic titration apparatus, comprising: a neutralization step for leaching; and one or more second washing steps for introducing and draining washing water into the titration vessel after the neutralization step.
[4] The pH calibration method for an automatic titration apparatus according to [3], wherein the basic side calibration step is the final step in the total pH calibration step.

[5] A titration vessel in which a sample solution is titrated with a basic titrant, a pH electrode inserted into the titration vessel, a storage unit for storing the relationship between the potential detected by the pH electrode and pH, and titration An acidic standard solution introduction mechanism that introduces an acidic standard solution into a container, a burette that supplies a basic titrant to a titration vessel, a wash water introduction mechanism that introduces wash water into a titration vessel, and a drain from the titration vessel A drainage mechanism and a calculation control device for controlling the whole are provided, and the automatic control is performed by the calculation control device so as to perform an acid side calibration step having the following steps (1) to (4) in order. Titration device.
(1) A storage step of introducing an acidic standard solution into a titration vessel by an acidic standard solution introduction mechanism, storing the pH of the acidic standard solution and the potential of the pH electrode in a storage unit, and then discharging the solution by a draining mechanism.
(2) One or more first washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.
(3) Neutralization step of introducing wash water into the titration vessel by the wash water introduction mechanism and neutralizing the wash water by adding a basic titrant with a burette and then draining by the drainage mechanism.
(4) One or more second washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.

[6] A titration container in which a sample solution is titrated with an acidic titrant, a pH electrode inserted into the titration container, a storage unit for storing a relationship between a potential detected by the pH electrode and pH, and a titration container A basic standard solution introduction mechanism for introducing a basic standard solution into a tublet, a burette for supplying an acidic titrant to a titration vessel, a washing water introduction mechanism for introducing washing water into a titration vessel, and draining from the titration vessel A drainage mechanism and a calculation control device for controlling the whole are provided, and the calculation control device is controlled to perform a basic side calibration step having the following steps (1) to (4) in order. Automatic titrator.
(1) A storage step of introducing a basic standard solution into a titration vessel by a basic standard solution introducing mechanism, storing the pH of the basic standard solution and the potential of the pH electrode in a storage unit, and then discharging the solution by a draining mechanism. .
(2) One or more first washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.
(3) A neutralization step of introducing washing water into the titration vessel by the washing water introduction mechanism and neutralizing the washing water by adding an acidic titrant with a burette and then draining the solution by the drainage mechanism.
(4) One or more second washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.

According to the present invention, even if the number of times of water washing in the calibration operation is small, an error hardly occurs during the subsequent titration of the sample liquid. Therefore, the consumption of cleaning water is reduced and the time required for water cleaning can be easily shortened.
In addition, since the present invention does not require new equipment, reagents, etc., it can be carried out without causing an increase in cost.

<First Embodiment>
[Device configuration]
The automatic titration apparatus according to the first embodiment of the present invention will be described. As shown in FIG. 1, the automatic titration apparatus of the present embodiment contains a measurement liquid F containing a sample liquid S and performs titration with the titration liquid, and a measurement in the sample liquid S in the titration container 1. It is obtained from the burette 2 that supplies the titrant R that reacts with the target substance, the pH electrode 3 that detects the pH corresponding to the supply amount of the titrant R (hereinafter referred to as “titrate”), and the pH electrode 3. An arithmetic control device 4 to which a pH value to be input is input, a storage unit 5, a sampling mechanism for introducing the sample liquid S into the titration vessel 1, a zero standard solution introduction mechanism for introducing the zero standard solution BU1 into the titration vessel 1, An acidic standard solution introduction mechanism for introducing the span standard solution BU2 into the titration vessel 1, a washing water introduction mechanism for introducing the washing water W into the titration vessel 1, a drainage mechanism for draining liquid from the titration vessel, a measurement solution F, etc. From the stirring device 70 for stirring the It is.

The burette 2 includes a nozzle 2 a inserted into the titration container 1 and a pipe 2 b inserted into a titrant liquid tank TR that stores the titrant R. The nozzle 2a is inserted into the titration container 1 so as to be below the liquid level of the measurement liquid F. The titrant R is basic, and for example, an aqueous solution such as sodium hydroxide or potassium hydroxide can be used.
The pH electrode 3 is disposed such that the detection unit is inserted into the measurement liquid F.
The arithmetic and control unit 4 controls the operation of the entire automatic titration apparatus. Further, the end point is obtained based on the pH obtained from the pH electrode 3, and the concentration of the substance to be measured in the sample liquid S is calculated from the titration amount at the end point.
The storage unit 5 stores the relationship between the potential detected by the pH electrode 3 and the pH.

The sampling mechanism includes a sample liquid measuring unit 10, a pipe L 1 for supplying the sample liquid S together with the dilution water D from the sample liquid measuring unit 10 to the titration container 1, and a sample liquid from the sample liquid inlet 20 to the sample liquid measuring unit 10. A pipe L2 for guiding S, a sample liquid supply tank 21 provided in the pipe L2, a pipe L3 for guiding the dilution water D from the dilution water inlet 30 to the sample liquid measuring unit 10, and a pipe L3 provided in order from the upstream side It is composed of a dilution water metering pipe 31 and a liquid feed pump P1, a pipe L4 for guiding excess sample water S from the sample liquid metering unit 10 to the drain port 40, and a liquid feed pump P2 provided in the pipe L4. .
The sample liquid measuring unit 10 includes a three-way valve 11, a three-way valve 12, and a sample liquid measuring tube 13 provided between common ports (ports indicated by white and black triangles) of these valves.
The pipe L1 is connected to the normally closed port (port indicated by a black triangle) of the three-way valve 11, and the pipe L2 is connected to the normally open port (port indicated by a white triangle) of the three-way valve 11. A pipe L3 is connected to the 12 normally closed ports (ports indicated by black triangles), and a pipe L4 is connected to the normally open port (port indicated by the white triangles) of the three-way valve 12.
The sample liquid S contains or may contain an acidic component that reacts with the basic titrant R.

The zero standard solution introduction mechanism includes a standard solution tank T1 in which the zero standard solution BU1 is accommodated, a pipe L5 led from the standard solution tank T1 to the titration container 1, and a liquid feed pump P3 provided in the pipe L5. ing. As the zero standard solution BU1, a buffer solution having a pH around pH 7, for example, a phosphate buffer solution is used.
The acidic standard solution introduction mechanism includes a standard solution tank T2 in which the span standard solution BU2 is accommodated, a pipe L6 led from the standard solution tank T2 to the titration vessel 1, and a liquid feed pump P4 provided in the pipe L6. ing. As the span standard solution BU2, an acidic buffer solution, for example, a phthalate pH standard solution exhibiting a pH around pH 4 is used.
The cleaning water introduction mechanism is configured by a pipe L7 that guides the cleaning water W from the cleaning water inlet 50, and a two-way valve 51 provided in the pipe L7. As the cleaning water W, pure water, tap water or the like is used.
The pipes L1, L5, L6, and L7 are inserted into the titration container 1 so that the tips are arranged in a space above the liquid level of the measurement liquid F so that none of the pipes L1, L5, L6, and L7 touch the measurement liquid F.

The drainage mechanism is composed of a pipe L8 led from the titration vessel 1 to the drainage port 60, and a drainage trap 61 and an air pump P5 provided in the pipe L8 sequentially from the upstream side. The pipe L8 is inserted to the deepest position below the liquid surface of the measurement liquid F.
The stirring device 70 is always driven while the titration vessel 1 is filled with the measurement liquid F, the standard liquid, the cleaning liquid, and the like.

[PH calibration process]
The automatic titration apparatus of this embodiment performs a pH calibration process at a predetermined timing stored in the storage unit 5 or when a calibration command is input to the arithmetic control device 4 by key input or the like.
The pH calibration process performed by the automatic titration apparatus of the present embodiment includes a zero calibration process A and an acid side calibration process B performed subsequent to the zero calibration process A, as shown in FIG.

In the zero calibration step A, the zero standard solution BU1 is introduced into the titration vessel 1, the pH of the zero standard solution BU1 and the potential of the pH electrode 3 are stored in the storage unit 5, and then drained, and the storage step A1. And a washing step A2 for introducing the washing water W into the subsequent titration vessel 1 and draining it.
In the storage step A1, the liquid feeding pump P3 is operated to the titration vessel 1, the zero standard solution BU1 is supplied from the pipe L5, and the detected potential obtained from the pH electrode 3 for the supplied zero standard solution BU1 is set to the zero standard solution BU1. In the storage unit 5 in association with the pH. After that, the air pump P5 is operated to discharge the zero standard solution BU1 from the pipe L8.
In the cleaning step, the two-way valve 51 is opened and the cleaning water W is supplied from the pipe L7. Then, the cleaning water W supplied by the stirring device 70 is stirred to clean the inside of the titration container 1, and then the air pump P5 is operated to discharge the cleaning water W from the pipe L8. The washing step may be repeated multiple times as necessary.

  The acid side calibration step B includes a storage step B1 in which the span standard solution BU2 is introduced into the titration vessel 1 and the pH of the span standard solution BU2 and the potential of the pH electrode 3 are stored in the storage unit 5 and then discharged. The first washing step B2 for introducing and draining the washing water W into the titration container 1 after B1, and the washing water W is introduced into the titration container 1 after the first washing step B2, and this washing water W is used as the titrant R And neutralizing step B3 for discharging after neutralization, and a second cleaning step B4 for discharging the cleaning water W into the titration vessel 1 after the neutralizing step B3 for draining.

In the storage step B1, the liquid feeding pump P4 is operated to the titration vessel 1, the span standard solution BU2 is supplied from the pipe L6, and the detected potential obtained from the pH electrode 3 for the supplied span standard solution BU2 is determined as the span standard solution BU2. In the storage unit 5 in association with the pH. After that, the air pump P5 is operated to discharge the span standard solution BU2 from the pipe L8.
In the first cleaning step B2, the two-way valve 51 is opened and the cleaning water W is supplied from the pipe L7. Then, the cleaning water W supplied by the stirring device 70 is stirred to clean the inside of the titration container 1, and then the air pump P5 is operated to discharge the cleaning water W from the pipe L8. The first cleaning step B2 may be repeated a plurality of times as necessary.

In the neutralization step B3, the two-way valve 51 is opened and the cleaning water W is supplied to the titration vessel 1 from the pipe L7. Then, while stirring with the stirring device 70, the burette 2 is operated to supply the titrant R to the titration vessel 1 and neutralize the washing water W.
Since the amount of the titrant R required for neutralization is very small, the operation of the burette 2 is controlled so as to be injected in small amounts intermittently. Neutralization is performed until the value detected by the pH electrode 3 reaches around pH 7. When neutralization is completed, the air pump P5 is operated to discharge the neutralized wash water W from the pipe L8.

In the second cleaning step B4, the two-way valve 51 is opened and the cleaning water W is supplied from the pipe L7. Then, the cleaning water W supplied by the stirring device 70 is stirred to clean the inside of the titration container 1, and then the air pump P5 is operated to discharge the cleaning water W from the pipe L8. The first cleaning step B2 may be repeated a plurality of times as necessary.
Through the pH calibration step, the arithmetic and control unit 4 can recognize the detection potential obtained from the pH electrode 3 by converting it to pH.

[Sample solution measurement process]
The automatic titration apparatus of the present embodiment measures the sample solution S at a predetermined timing stored in the storage unit 5 or when a measurement command is input to the arithmetic control device 4 by key input or the like. The sample solution measurement step can be performed after the pH calibration step.
In the sample liquid measurement process performed by the automatic titration apparatus of the present embodiment, the sampling step C1, the titration step C2, the concentration calculation step C3, the output step C4, and the washing step C5 are sequentially performed.

In the sampling step C1, first, the liquid feed pump P2 is operated with the normally open port of the three-way valve 11 and the normally open port of the three-way valve 12 in the sample liquid measuring unit 10 open, and the sample liquid S is measured from the pipe L2. It flows to the pipe L4 via the pipe 13.
Next, the liquid feed pump P1 is operated by switching the normally closed port of the three-way valve 11 and the normally closed port of the three-way valve 12 to open, and the diluted water D previously measured by the diluted water measuring pipe 31 is supplied from the pipe L3 to the sample liquid. It flows to the pipe L1 via the measuring pipe 13. As a result, a fixed amount of the sample solution S filled in the sample solution measuring tube 13 is supplied to the titration container 1 together with a fixed amount of dilution water D.

A titration step C2 is performed after the sampling step C1. In the titration step C2, the pH corresponding to the titration amount is detected by the pH electrode 3 while operating the burette 2 to supply the titrant R to the titration vessel 1.
The operation of the burette 2 is appropriately controlled by the arithmetic control device 4. For example, the titration liquid R is continuously injected at the beginning of titration, and after reaching the pH in the vicinity of the end point, control is performed so as to inject a small amount intermittently.
Then, the end point is obtained from the detected pH by the arithmetic and control unit 4. There is no limitation on how to obtain the end point, and a known method can be employed. For example, a method of setting the end point when the maximum value of the differential value of pH is obtained, and a method of setting the end point when the pH reaches a certain value can be adopted.
When the end point is obtained, the titration is finished. It should be noted that the titration is also terminated when the end point cannot be obtained even if the titration amount significantly exceeds the normally assumed amount.

After the titration step C2, concentration calculation is performed as a concentration calculation step C3. As is well known, the concentration of the measurement target component in the sample liquid S is calculated from the volume of the sample liquid supplied to the titration vessel 1, the concentration of the component reacting with the measurement target component in the titration liquid, and the titration amount at the end point. it can. Note that the volume of the sample solution (in this embodiment, the amount filled in the sample solution measuring tube 13 of the sample solution measuring unit 10) can be accurately obtained by titrating standard data with a known concentration in advance.
If the end point is not obtained in the titration step C2, the concentration calculation step C3 is omitted.

After the density calculation step C3, an output step C4 is performed. In the output step C4, when the end point is not obtained in the concentration of the measurement target component in the sample liquid S obtained in the concentration calculation step C3, and in the titration step C2, that fact is output. Further, other information such as titration amount, temperature, time, etc. is output as necessary.
The output method is not limited, and examples thereof include main transmission to a computer or the like disposed in a control center, print output by a printer, display output by a display, and the like. These output methods may be used in combination.

  A cleaning step C5 is performed after the output step C4. In the washing step C5, the two-way valve 51 is opened and the washing water W is supplied from the pipe L7. Then, the cleaning water W supplied by the stirring device 70 is stirred to clean the inside of the titration container 1, and then the air pump P5 is operated to discharge the cleaning water W from the pipe L8. The washing step may be repeated multiple times as necessary.

In the present embodiment, since the span standard solution BU2 remaining in the cleaning water W is neutralized by the neutralization step B3, the first cleaning step B2 and the second cleaning step B4 in the acid side calibration step B are performed a small number of times. For example, the standard solution BU2 can be accurately removed from the titration container 1 even once. Therefore, the usage-amount of the washing water W in a pH calibration process can be suppressed.
In addition, since the neutralization step B3 is performed by operating the same burette 2 used in the sample solution measuring process and adding a small amount of the same titrant R used in the sample solution measuring process, a new apparatus or reagent can be used. Therefore, the present invention can be implemented at low cost.
In addition, since the acid side calibration process B having the neutralization step B3 is the final process of the pH calibration process, in the sample liquid measurement process performed first after the pH calibration process, due to the influence of the acidic span standard solution BU2. Measurement errors can be avoided.

<Second Embodiment>
[Device configuration]
An automatic titration apparatus according to a second embodiment of the present invention will be described. The automatic titration apparatus according to the second embodiment is provided with a basic standard solution introduction mechanism instead of the acidic standard solution introduction mechanism, and the automatic titration according to the first embodiment is different except that the properties of the sample S and the titrant R are different. Since it is the same as the apparatus, it demonstrates using FIG. Detailed description of the same configuration as that of the automatic titration apparatus according to the first embodiment is omitted.
That is, the automatic titration apparatus according to the second embodiment includes a titration container 1, a burette 2, a pH electrode 3, an arithmetic control device 4, a storage unit 5, a sampling mechanism, a zero standard solution introduction mechanism, as shown in FIG. A basic standard solution introduction mechanism for introducing the span standard solution BU2 into the titration vessel 1, a washing water introduction mechanism for introducing the washing water W into the titration vessel 1, a drainage mechanism for draining from the titration vessel, and a measuring solution It basically comprises a stirring device 70 for stirring F and the like.

The titrant R supplied to the titration vessel 1 by the burette 2 is acidic, and for example, an aqueous solution such as hydrochloric acid or sulfuric acid can be used.
The sample liquid S contains or may contain a basic component that reacts with the acidic titrant R.
The basic quasi-liquid introduction mechanism includes a standard liquid tank T2 in which the span standard liquid BU2 is accommodated, a pipe L6 led from the standard liquid tank T2 to the titration container 1, and a liquid feed pump P4 provided in the pipe L6. Has been. As the span standard solution BU2, a basic buffer solution, for example, a borate pH standard solution having a pH of around pH 9 is used.

[PH calibration process]
The automatic titration apparatus of this embodiment performs a pH calibration process at a predetermined timing stored in the storage unit 5 or when a calibration command is input to the arithmetic control device 4 by key input or the like.
The pH calibration process performed by the automatic titration apparatus of this embodiment includes a zero calibration process A and a basic side calibration process D performed subsequent to the zero calibration process A, as shown in FIG.
The zero calibration process A is the same as the zero calibration process A of the first embodiment.

The basic side calibration process D includes a storage step D1, a first cleaning step D2, a neutralization step D3, and a second cleaning step D4.
The storage step D1 is the same as the storage step B1 of the first embodiment except that a basic buffer is used as the span standard solution BU2. The first cleaning step D2 is the same as the first cleaning step B2 of the first embodiment.
The neutralization step D3 is the same as the neutralization step B3 of the first embodiment except that an acidic titrant is used as the titrant R.
The second cleaning step D4 is the same as the second cleaning step B4 of the first embodiment.

[Sample solution measurement process]
The automatic titration apparatus of the present embodiment measures the sample solution S at a predetermined timing stored in the storage unit 5 or when a measurement command is input to the arithmetic control device 4 by key input or the like. The sample solution measurement step can be performed after the pH calibration step. The sample liquid measurement process is the same as that of the first embodiment except that the properties of the sample liquid S are different.

In this embodiment, since the span standard solution BU2 remaining in the cleaning water W is neutralized by the neutralization step D3, the first cleaning step D2 and the second cleaning step D4 in the basic side calibration step D are performed a small number of times. For example, the standard solution BU2 can be accurately removed from the titration vessel 1 even once. Therefore, the usage-amount of the washing water W in a pH calibration process can be suppressed.
In addition, the neutralization step D3 can be performed by operating the same burette 2 used in the sample solution measuring process and adding a small amount of the same titrant R used in the sample solution measuring process. Therefore, the present invention can be implemented at low cost.
In addition, since the basic side calibration step D having the neutralization step D3 is the final step of the pH calibration step, the basic span standard solution BU2 in the sample solution measurement step performed first after the pH calibration step. Measurement errors due to the influence can be avoided.

It is a schematic block diagram of the automatic titration apparatus which concerns on 1st Embodiment and 2nd Embodiment of this invention. It is a flowchart of the operation | movement procedure of the automatic titration apparatus which concerns on 1st Embodiment of this invention. It is a flowchart of the operation | movement procedure of the automatic titration apparatus which concerns on 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Titration container, 2 ... Bullet, 3 ... pH electrode, 4 ... Calculation control apparatus, 5 ... Memory | storage part

Claims (6)

A pH calibration method for an automatic titration device that titrates a sample solution with a basic titrant while detecting pH with a pH electrode inserted in the titration vessel,
It has an acid side calibration process to calibrate with an acid standard solution.
The acid side calibration process introduces an acidic standard solution into the titration vessel, stores the pH of the acidic standard solution and the potential of the pH electrode and then drains it, and introduces wash water into the titration vessel after the storage step. One or more first washing steps for draining, a neutralizing step for introducing washing water into the titration vessel after the first washing step, neutralizing the washing water with the titration liquid, and then draining, A pH calibration method for an automatic titration apparatus, comprising one or more second washing steps for introducing washing water into a titration container after the sum step and draining it.   The pH calibration method for an automatic titration apparatus according to claim 1, wherein the acid side calibration step is the final step in the total pH calibration step. A pH calibration method for an automatic titration apparatus that titrates a sample solution with an acidic titrant while detecting pH with a pH electrode inserted in the titration vessel,
It has a basic calibration process to calibrate with a basic standard solution.
The basic calibration process includes a storage step of introducing a basic standard solution into the titration vessel, storing the pH of the basic standard solution and the potential of the pH electrode, and then draining, and washing the titration vessel after the storage step. One or more first washing steps for introducing and draining water, and a neutralizing step for introducing the washing water into the titration vessel after the first washing step, neutralizing the washing water with the titration liquid and then draining And a pH calibration method for an automatic titration apparatus, comprising one or more second washing steps for introducing washing water into the titration container after the neutralization step and draining it.   The pH calibration method for an automatic titration apparatus according to claim 3, wherein the basic side calibration step is the final step in the total pH calibration step. A titration vessel in which a sample solution is titrated with a basic titrant, and
A pH electrode inserted into the titration vessel;
a storage unit for storing the relationship between the potential detected by the pH electrode and the pH;
An acidic standard solution introduction mechanism for introducing an acidic standard solution into the titration vessel;
A burette for supplying a basic titrant to the titration vessel;
A washing water introduction mechanism for introducing washing water into the titration vessel;
A drainage mechanism for draining from the titration vessel;
It is equipped with a calculation control device that controls the whole,
An automatic titration apparatus controlled to perform an acid side calibration step having the following steps (1) to (4) in order by an arithmetic and control unit.
(1) A storage step of introducing an acidic standard solution into a titration vessel by an acidic standard solution introduction mechanism, storing the pH of the acidic standard solution and the potential of the pH electrode in a storage unit, and then discharging the solution by a draining mechanism.
(2) One or more first washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.
(3) Neutralization step of introducing wash water into the titration vessel by the wash water introduction mechanism and neutralizing the wash water by adding a basic titrant with a burette and then draining by the drainage mechanism.
(4) One or more second washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism. A titration vessel in which the sample solution is titrated with an acidic titrant,
A pH electrode inserted into the titration vessel;
a storage unit for storing the relationship between the potential detected by the pH electrode and the pH;
A basic standard solution introduction mechanism for introducing a basic standard solution into a titration vessel;
A burette for supplying an acidic titrant to the titration vessel;
A washing water introduction mechanism for introducing washing water into the titration vessel;
A drainage mechanism for draining from the titration vessel;
It is equipped with a calculation control device that controls the whole,
An automatic titration apparatus controlled to perform a basic side calibration step having the following steps (1) to (4) in order by an arithmetic and control unit.
(1) A storage step of introducing a basic standard solution into a titration vessel by a basic standard solution introducing mechanism, storing the pH of the basic standard solution and the potential of the pH electrode in a storage unit, and then discharging the solution by a draining mechanism. .
(2) One or more first washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.
(3) A neutralization step of introducing washing water into the titration vessel by the washing water introduction mechanism and neutralizing the washing water by adding an acidic titrant with a burette and then draining the solution by the drainage mechanism.
(4) One or more second washing steps in which washing water is introduced into the titration vessel by the washing water introduction mechanism and then drained by the drainage mechanism.

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