JP7455249B1 - Electrochemical measurement method, electrochemical measurement device, and program - Google Patents

Abstract

[Problem] To provide an electrochemical measurement method and an electrochemical measurement device capable of measuring the concentration of a test substance in a test liquid with high accuracy using an electrochemical sensor equipped with a working electrode having an electrode film made of a material containing diamond. [Solution] An electrochemical measurement method for measuring the concentration of a test substance in a test liquid, comprising the steps of: mounting an electrochemical sensor equipped with at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material on an electrochemical measurement device; and carrying out electrochemical measurement of the concentration of the test substance with the working electrode and the counter electrode in contact with the test liquid, and if a predetermined condition is met, further comprising the step of carrying out a pretreatment once or a plurality of times before the step of carrying out the electrochemical measurement, in which a potential exceeding the oxidation-reduction potential of the test substance is applied to the working electrode with at least the working electrode and the counter electrode in contact with a treatment liquid containing the test substance, thereby causing an electrochemical reaction on the surface of the working electrode. [Selected Figure] Figure 4

Description

The present disclosure relates to an electrochemical measurement method, an electrochemical measurement device, and a program.

Conventionally, there has been an electrochemical measurement method in which an electrochemical sensor equipped with a working electrode having an electrode film made of a material containing diamond is attached to an electrochemical measuring device to measure the concentration of a test substance in a test liquid. has been proposed (see, for example, Patent Document 1).

International Publication No. 2020/091033

However, when the concentration of the analyte in the test liquid is measured by electrochemical measurement using an electrochemical sensor equipped with a working electrode having an electrode film made of a material containing diamond, the concentration of the analyte cannot be measured. Measurement accuracy may be reduced.

An object of the present disclosure is to provide an electrochemical measurement method capable of measuring the concentration of a test substance in a test liquid with high precision using an electrochemical sensor equipped with a working electrode having an electrode film made of a material containing diamond. and to provide an electrochemical measuring device.

According to one aspect of the present disclosure,
An electrochemical measurement method for measuring the concentration of a test substance in a test liquid, the method comprising:
Attaching an electrochemical sensor to the electrochemical measuring device, the method comprising at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material;
carrying out electrochemical measurement of the concentration of the test substance with the working electrode and the counter electrode in contact with the test liquid,
If at least one of the following (1) to (4) applies, at least the working electrode and the pair are added to the treatment liquid containing the test substance before the step of performing the electrochemical measurement. A step of applying a potential exceeding the oxidation-reduction potential of the test substance to the working electrode while the electrodes are in contact with each other, and performing pretreatment once or multiple times to cause an electrochemical reaction on the surface of the working electrode. An electrochemical measurement method is provided, further comprising:
(1) When performing the step of performing the electrochemical measurement for the first time after performing the step of attaching the electrochemical sensor to the electrochemical measurement device; (2) When the step of performing the electrochemical measurement is performed first; In the case where the step of performing the electrochemical measurement is repeatedly performed using the same electrochemical sensor without removing the sensor, a predetermined period of time has elapsed since the time when the step of performing the previous electrochemical measurement was performed. (However, this excludes cases where the step of performing the pretreatment is performed after the previous step of performing the electrochemical measurement.)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measuring device, the electrochemical (However, this excludes cases where the step of performing the electrochemical measurement is performed after the previous step of performing the pretreatment)
(4) In the case where the step of performing the electrochemical measurement using the same electrochemical sensor is repeated without removing the electrochemical sensor from the electrochemical measuring device, the previous electrochemical measurement is repeated. When performing electrochemical measurement of the concentration of a test substance different from the test substance measured in the process to be carried out.

According to other aspects of the disclosure:
An electrochemical measuring device for measuring the concentration of a test substance in a test liquid,
At least, the electrochemical sensor is configured such that it can be attached to an electrochemical sensor including a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material,
A preset potential is applied to the working electrode while at least the working electrode and the counter electrode of the electrochemical sensor attached to the electrochemical measurement device are in contact with the treatment liquid containing the analyte. a function of performing a pretreatment a preset number of times to cause an electrochemical reaction on the surface of the working electrode;
a function of performing electrochemical measurement of the concentration of the test substance while the working electrode and the counter electrode are in contact with the test liquid;
If at least one of the following (1) to (3) applies, a function to prompt the implementation of the pretreatment before performing the electrochemical measurement;
An electrochemical measurement device with
(1) When performing the electrochemical measurement for the first time after installing the electrochemical sensor in the electrochemical measurement device, (2) When performing the electrochemical measurement for the first time without removing the electrochemical sensor from the electrochemical measurement device, In the case where the electrochemical measurement is repeatedly performed using the electrochemical sensor, when the electrochemical measurement is performed after a predetermined time has elapsed from the time when the previous electrochemical measurement was performed (provided that , except when the pretreatment is performed after the previous electrochemical measurement)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measuring device, the electrochemical (Excluding cases where the electrochemical measurement is performed after the previous pretreatment)

According to still other aspects of the present disclosure,
An electrochemical measuring device for measuring the concentration of a test substance in a test liquid,
At least, the electrochemical sensor is configured such that it can be attached to an electrochemical sensor including a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material,
comprising a display section that displays the concentration of the test substance,
A function of selecting a calibration curve based on input information from the measuring person when the measuring person inputs in advance instructions for the test substance to be measured;
A preset potential is applied to the working electrode while at least the working electrode and the counter electrode of the electrochemical sensor attached to the electrochemical measurement device are in contact with the treatment liquid containing the analyte. a function of performing a pretreatment a preset number of times to cause an electrochemical reaction on the surface of the working electrode;
a function of carrying out electrochemical measurement of a current value corresponding to the concentration of the test substance in a state in which at least the working electrode and the counter electrode are in contact with the test liquid;
a function of calculating the concentration of the test substance from the measured current value using the selected calibration curve;
a function of displaying the calculated concentration of the test substance on the display section;
If at least one of the following (1) to (4) applies, a function that prompts the implementation of the pretreatment before performing the electrochemical measurement;
An electrochemical measurement device having:
(1) When performing the electrochemical measurement for the first time after installing the electrochemical sensor in the electrochemical measurement device, (2) When performing the electrochemical measurement for the first time without removing the electrochemical sensor from the electrochemical measurement device, In the case where the electrochemical measurement is repeatedly performed using the electrochemical sensor, when the electrochemical measurement is performed after a predetermined time has elapsed from the time when the previous electrochemical measurement was performed (provided that , except when the pretreatment is performed after the previous electrochemical measurement)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measurement device, the electrochemical (Excluding cases where the electrochemical measurement is performed after the previous pretreatment)
(4) In the case where the electrochemical measurement is repeatedly carried out using the same electrochemical sensor without removing the electrochemical sensor from the electrochemical measurement device, the electrochemical measurement that was measured in the previous electrochemical measurement When carrying out the electrochemical measurement of the concentration of another test substance different from the test substance.

According to still other aspects of the present disclosure,
It has at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material, and is attached to an electrochemical measuring device for measuring the concentration of a test substance in a test liquid. a step of performing electrochemical measurement of the concentration of the test substance in a state where the working electrode and the counter electrode of the electrochemical sensor are in contact with the test liquid;
If at least one of the following (1) to (4) applies, at least the working electrode and the electrode are added to the treatment solution containing the test substance before the electrochemical measurement procedure. A procedure of applying a potential exceeding the redox potential of the test substance to the working electrode while the electrodes are in contact with each other, and performing pretreatment once or multiple times to cause an electrochemical reaction on the surface of the working electrode. and,
A program is provided that is configured to cause a computer to execute.
(1) When the electrochemical sensor is attached to the electrochemical measurement device, when the procedure for performing the electrochemical measurement is first performed (2) When the electrochemical sensor is removed from the electrochemical measurement device In the case where the procedure for performing the electrochemical measurement is repeatedly performed using the same electrochemical sensor without any interruption, after a predetermined period of time has elapsed from the time when the procedure for performing the previous electrochemical measurement was performed. , when causing the procedure for performing the electrochemical measurement to be executed (however, excluding the case where the procedure for performing the pretreatment is executed after the previous procedure for performing the electrochemical measurement)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measuring device, the electrochemical (However, this excludes cases where the procedure for performing the electrochemical measurement is executed after the previous procedure for performing the pretreatment)
(4) In the case where the procedure for performing the electrochemical measurement using the same electrochemical sensor is repeatedly performed without removing the electrochemical sensor from the electrochemical measurement device, the electrochemical measurement performed previously When performing electrochemical measurement of the concentration of another test substance different from the test substance measured by the procedure of

According to the present disclosure, an electrochemical measurement method is capable of measuring the concentration of a test substance in a test liquid with high precision using an electrochemical sensor equipped with a working electrode having an electrode film made of a material containing diamond. and an electrochemical measuring device.

1 is an example of a schematic perspective view of an electrochemical sensor attached to an electrochemical measurement device in one embodiment of the present disclosure. 2 is a sectional view taken along line AA of the electrochemical sensor shown in FIG. 1. FIG. FIG. 1 is a block configuration diagram of an electrochemical measurement device according to one aspect of the present disclosure. FIG. 2 is a diagram illustrating an example of an operation flow of an electrochemical device (measurement flow of an electrochemical side method) in one embodiment of the present disclosure. FIG. 2 is a schematic diagram showing a state in which an electrode group of an electrochemical sensor attached to an electrochemical measuring device according to an embodiment of the present disclosure is brought into contact with a test liquid containing a test substance.

<Findings obtained by the inventors>
Conventionally, the concentration of an analyte in a test liquid containing a analyte (e.g., ozone (O ₃ )) at a predetermined concentration has been conventionally determined using an electrochemical sensor in which at least the working electrode is a chip-shaped diamond electrode. It is proposed to measure A diamond electrode is an electrode that includes a conductive substrate and an electrode film formed on the conductive substrate and made of polycrystalline diamond. In order to increase the measurement sensitivity of diamond electrodes, various techniques have been proposed for performing various surface treatments on the working electrode. However, an electrochemical sensor in which the working electrode is a diamond electrode has a problem in that the concentration of an analyte cannot be measured electrochemically with good reproducibility. The present inventors have conducted extensive research on this subject. As a result, even if various surface treatments have been performed on the working electrode, the storage conditions of the working electrode (electrochemical sensor) after the surface treatment, the time elapsed since the surface treatment, etc. It was found that the surface of the working electrode (the surface that contributes to electrochemical measurements) changes, resulting in a decrease (deterioration) in the sensitivity of the sensor. Even in the case of an electrochemical sensor with reduced sensitivity in this way, the working electrode is subjected to measurement pretreatment (herein simply referred to as "pretreatment") under predetermined conditions before electrochemical measurements are performed. We have discovered that by performing the following steps, the sensitivity of the sensor can be restored and the concentration of the analyte can be measured with high precision and reproducibility by electrochemical measurement. This is a new finding discovered by the present inventors.

The present disclosure has been made based on the above-mentioned problems and findings obtained by the present inventors.

<One aspect of the present disclosure>
One aspect of the present disclosure will be described below with reference to FIGS. 1 to 4.

(1) Structure of electrochemical sensor An example of an electrochemical sensor 10 (hereinafter also referred to as "sensor 10") that can be detached from electrochemical measuring device 100 (hereinafter also referred to as "measuring device 100") according to the present embodiment , will be explained with reference to FIGS. 1 and 2.

The sensor 10 is configured as a three-electrode sensor equipped with a working electrode, a counter electrode, and a reference electrode. Note that the sensor 10 may be a two-electrode sensor equipped with a working electrode and a counter electrode. In this aspect, an example in which the sensor 10 is configured as a three-electrode sensor will be described.

As shown in FIGS. 1 and 2, the sensor 10 includes a support base material 11 (hereinafter also referred to as "base material 11"). The base material 11 is a substrate-like member that supports a working electrode 15, a counter electrode 16, a reference electrode 17, etc., which will be described later. The base material 11 is configured as a sheet-like (plate-like) member. The base material 11 can be formed of an insulating material such as a composite resin, ceramic, glass, or plastic having insulating properties, for example. The base material 11 is preferably made of, for example, glass epoxy resin or polyethylene terephthalate (PET). Further, the base material 11 may be a semiconductor substrate or a metal substrate configured such that the surface on which the working electrode 15, the counter electrode 16, the reference electrode 17, etc. are provided has insulating properties. The planar shape of the base material 11 can be, for example, rectangular. The base material 11 has a predetermined physical strength and mechanical strength, such as strength that will not bend or break during electrochemical measurements.

On one of the two main surfaces of the base material 11 (hereinafter also referred to as the "upper surface of the base material 11"), there is a surface extending from one end to the other end in the longitudinal direction of the base material 11. Three wires (electrical wires) 12, 13, and 14 are arranged apart from each other. The materials for forming the wirings 12 to 14 include various noble metals such as copper (Cu), gold (Au), platinum (Pt), silver (Ag), and palladium (Pd), aluminum (Al), iron (Fe), and nickel. Examples include various metals such as (Ni), chromium (Cr), and titanium (Ti), alloys containing these noble metals or metals as main components, oxides of the above noble metals, metals, or alloys, and carbon. The wirings 12 to 14 may be formed using the same material, or may be formed using different materials. The wirings 12 to 14 can be formed by a subtractive method, a semi-additive method, or the like. Further, the wirings 12 to 14 can also be formed by a printing method such as screen printing, gravure printing, offset printing, or inkjet printing, or a vapor deposition method.

A working electrode 15 is electrically connected to one end of the wiring 12 via a conductive bonding material 18 (see FIG. 2). A counter electrode 16 is electrically connected to one end of the wiring 13 via a conductive bonding material 18 . A reference electrode 17 is electrically connected to one end of the wiring 14 via a conductive bonding material 18 . As the bonding material 18, a conductive paste (conductive adhesive), a conductive tape, or the like can be used.

The working electrode 15, the counter electrode 16, and the reference electrode 17 are diamond electrodes each having an electrode film made of a material containing diamond, specifically, an electrode film made of boron-doped polycrystalline diamond. This is a diamond electrode (hereinafter also referred to as a "BDD electrode") having a diamond electrode. The BDD electrode is a chip-shaped electrode (electrode tip) that includes an electrode film 21 made of polycrystalline diamond or the like and a conductive substrate 22 that supports the electrode film 21. In this specification, the working electrode 15, the counter electrode 16, and the reference electrode 17 may be collectively referred to as an electrode group 30. Details of the working electrode 15, counter electrode 16, and reference electrode 17 will be described later.

An insulating resin 19 (see FIG. 2 (see). The insulating resin 19 can be made of thermosetting resin or ultraviolet curable resin. As the thermosetting resin or ultraviolet curable resin, epoxy-based insulating resin, novolac-based insulating resin, etc. can be used. The insulating resin 19 is, for example, a liquid insulating resin (hereinafter also referred to as "liquid resin") before hardening that is applied around each bonding material 18 and to each of the working electrode 15, counter electrode 16, and reference electrode 17. It can be provided by applying the liquid resin to the surrounding area and curing the liquid resin by heating or irradiating with ultraviolet rays. Note that the application and curing of the liquid resin involves electrically connecting the working electrode 15 and the wiring 12, electrically connecting the counter electrode 16 and the wiring 13, and electrically connecting the reference electrode 17 and the wiring 14. It is done after. For example, the liquid resin is applied so as to cover the bonding material 18, the side surface of the working electrode 15, the side surface of the counter electrode 16, and the side surface of the reference electrode 17 without exposing them. Further, the liquid resin is applied so as not to adhere to the surface of the working electrode 15, the counter electrode 16, and the reference electrode 17. Note that "the surface of the working electrode 15,""the surface of the counter electrode 16," and "the surface of the reference electrode 17" each refer to the surface of the electrode film of each electrode. Of the two main surfaces, it refers to the surface opposite to the surface in contact with the conductive substrate 22. “Surface of working electrode 15,” “surface of counter electrode 16,” and “surface of reference electrode 17” are surfaces (detection surfaces) that contribute to the detection of the test substance (for example, O ₃ ) in the test liquid. You can say that.

The wirings 12 to 14 are arranged so that when the electrode group 30 is brought into contact with a test liquid or processing liquid (hereinafter also referred to as "test liquid, etc."), the test liquid etc. comes into contact with the wirings 12 to 14. It is covered with a waterproof member 20 made of an insulating material or the like so that there is no leakage. Note that the waterproof member 20 is configured to expose an end different from the end connected to each electrode among the two ends each of the wirings 12 to 14 has.

As described above, the working electrode 15, counter electrode 16, and reference electrode 17 all include the electrode film 21 and the conductive substrate 22 (hereinafter also referred to as "substrate 22") that supports the electrode film 21. This is the BDD electrode provided. The BDD electrode is configured as a vertical electrode that conducts from the back surface of the substrate 22. The "back surface of the substrate 22" herein refers to the surface opposite to the surface on which the electrode film 21 is provided, of the two main surfaces that the substrate 22 has.

The electrode film 21 is made of polycrystalline diamond. Specifically, the electrode film 21 is a polycrystalline film (polycrystalline diamond film) made of a diamond crystal containing boron (B) as a dopant, that is, a diamond crystal having p-type conductivity. A diamond crystal is a crystal in which carbon (C) atoms are arranged in a pattern called a diamond crystal structure. Further, the electrode film 21 may be a diamond-like carbon (DLC) film doped with B. The B concentration in the electrode film 21 can be measured by secondary ion mass spectrometry (SIMS), and can be set to, for example, 5×10 ¹⁹ cm ⁻³ or more and 5×10 ²¹ cm ⁻³ or less. SIMS is a method of measuring the concentration of a predetermined substance by detecting ions (secondary ions) generated when the surface of the electrode film 21 is irradiated with a beam of ions (primary ions) using a mass spectrometer. .

The electrode film 21 can be grown (deposited, synthesized) by a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, or the like. Examples of the CVD method include a hot filament CVD method using a tungsten filament, a plasma CVD method, and the like, and examples of the PVD method include an ion beam method, an ionized vapor deposition method, and the like. The thickness of the electrode film 21 can be, for example, 0.5 μm or more and 10 μm or less, preferably 1 μm or more and 6 μm or less, and more preferably 2 μm or more and 4 μm or less.

As the substrate 22, a flat substrate made of a low resistance material is used. As the substrate 22, a substrate that is composed of silicon (Si) as a main element and contains a p-type dopant such as boron (B) at a predetermined concentration, such as a p-type single crystal Si substrate, can be used. As the substrate 22, a p-type polycrystalline Si substrate can also be used. The B concentration in the substrate 22 is, for example, 5×10 ¹⁸ cm ⁻³ or more and 1.5×10 ²⁰ cm ⁻³ or less, preferably 5×10 ¹⁸ cm ⁻³ or more and 1.2×10 ²⁰ cm ^{−3 or} less. I can do it. By setting the B concentration in the substrate 22 within the above range, it is possible to reduce the specific resistance of the substrate 22 while avoiding a decrease in manufacturing yield or performance deterioration of the substrate 22.

The thickness of the substrate 22 can be, for example, 350 μm or more. This makes it possible to use a commercially available single-crystal Si substrate with a diameter of 6 inches or 8 inches as the substrate 22 without back-lapping and adjusting the thickness. As a result, it becomes possible to increase the productivity of BDD electrodes and reduce manufacturing costs. Although the upper limit of the thickness of the substrate 22 is not particularly limited, the thickness of a Si substrate generally available on the market at present is about 775 μm for a single crystal Si substrate with a diameter of 12 inches. Therefore, the upper limit of the thickness of the substrate 22 in the current technology can be, for example, about 775 μm.

As the substrate 22, a substrate other than a substrate composed of Si as a main element (Si substrate) can also be used. For example, as the substrate 22, a substrate configured using a Si compound such as a silicon carbide substrate (SiC substrate) can also be used.

Note that it is also possible to use a metal substrate composed of niobium (Nb), molybdenum (Mo), titanium (Ti), or the like as a main element as the substrate 22. However, when a metal substrate is used, leakage current is likely to occur, so it is preferable to use a Si substrate or a substrate made of a Si compound as the substrate 22.

It is preferable that at least the working electrode 15 is subjected to a surface treatment to increase sensor sensitivity. Specifically, for the working electrode 15, a current peak corresponding to the concentration of the test substance (for example, O ₃ ) in the test liquid is observed in a voltammogram obtained by linear sweep voltammetry (LSV) measurement. It is preferable that such a surface treatment is applied. For example, when the test substance is dissolved ozone in water, the electrode group 30 (i.e., the working electrode 15, the counter electrode 16, and the reference electrode 17) is placed in a solution containing O ₃ at a high concentration (for example, a concentration of 10 ppm or more). A treatment is applied to the working electrode 15 to cause a predetermined electrochemical reaction on the surface (detection surface) of the working electrode 15 by applying a potential exceeding the oxidation-reduction potential of O ₃ to the working electrode 15 while in contact with the working electrode 15 . preferable. Thereby, the sensitivity of the sensor 10 can be increased to, for example, saturation sensitivity (the maximum sensitivity that the sensor 10 has). As a result, when LSV measurement (electrochemical measurement) is performed using the sensor 10 having the working electrode 15, in the obtained voltammogram, even if the reference electrode 17 is a diamond electrode, the O ₃ concentration in the test liquid is The current peak corresponding to can be observed.

Here, the saturation sensitivity of the sensor 10 is determined by crystal characteristics such as the crystal grain size and orientation of the BDD crystal constituting the electrode film 21 of each electrode of the sensor 10, the amount of dopant doped in the electrode film 21, the electrode size, Since it is determined by the specifications of the sensor 10 (for example, the arrangement of each electrode), it may differ slightly from sensor to sensor 10. Note that the "sensitivity of the sensor 10" in this specification is defined by the slope of the calibration curve created using the sensor 10, and simply, the "sensitivity of the sensor 10" is defined as the current density peak value corresponding to the concentration of a certain test substance. It can be defined as the slope of the straight line connecting to the origin. The "current density peak value" herein refers to the value obtained by dividing the current peak value obtained by LSV measurement using the sensor 10 by the planar area of the working electrode 15 and the concentration of the test substance in the test liquid (= It is the absolute value of current peak value/(planar area of working electrode 15/concentration of test substance)).

The outer shape (planar shape) of the working electrode 15, counter electrode 16, and reference electrode 17 is each formed into a rectangular shape, for example, a rectangular shape when viewed from above in a direction perpendicular to the main surface of the substrate 22. ing. Note that the working electrode 15, the counter electrode 16, and the reference electrode 17 may be formed into the same planar shape, or may be formed into different planar shapes.

The plane area of the working electrode 15 is, for example, 1 mm ² or more and 100 mm ² or less. Although the planar area of the counter electrode 16 and the planar area of the reference electrode 17 are not particularly limited, they are each, for example, 1 mm ² or more and 100 mm ² or less. Note that the planar area of the working electrode 15, the planar area of the counter electrode 16, and the planar area of the reference electrode 17 refer to the planar area of each electrode when viewed from above in a direction perpendicular to the main surface of the substrate 22. It is the area. Since the electrode film 21 is provided over the entire crystal deposition surface of the substrate 22, the planar area of each electrode contributes to the planar area of the electrode film 21 of each electrode, that is, the detection of O ₃ in the test liquid. This is the area of the surface.

By setting the working electrode 15, counter electrode 16, and reference electrode 17 to have a planar area of 1 mm ² or more, respectively, it is possible to suppress deterioration in handling properties and mounting stability of each electrode. Furthermore, when the working electrode 15 has a planar area of 1 mm ² or more, it becomes easy to obtain a sensor 10 having the sensitivity necessary for measuring the concentration of a test substance with high precision by electrochemical measurement. Furthermore, it is possible to prevent the current flowing during electrochemical measurement from becoming too small, and as a result, it is possible to avoid a decrease in the S/N ratio (=ratio of current flowing through the working electrode 15 (signal current)/noise current). Further, since the working electrode 15, the counter electrode 16, and the reference electrode 17 each have a planar area of 100 mm ² or less, it is possible to avoid increasing the size of the sensor 10.

Note that the working electrode 15, the counter electrode 16, and the reference electrode 17 may each have the same planar area, or may have different planar areas as long as they are within the range of the above-mentioned planar area. It's okay. FIG. 1 shows an example in which the working electrode 15, counter electrode 16, and reference electrode 17 have the same planar area.

(2) Configuration of electrochemical measurement device The electrochemical measurement device 100 according to this embodiment will be described with reference to FIG. 3. The measuring device 100 according to this embodiment is a device that measures the concentration of a test substance in a test liquid, and specifically, uses linear sweep voltammetry (LSV) measurement (or cyclic voltammetry) as an electrochemical measurement. CV) measurement) to measure the concentration of a test substance. The test substance is not particularly limited, and various known substances can be measured. Examples of the test substance include ozone (O ₃ ), citric acid, caffeine, and chlorine.

The measuring device 100 is configured such that the above-described sensor 10 can be attached or detached (installed and removed). Furthermore, the measuring device 100 has a function as, for example, a potentiostat. Further, the measuring device 100 (measuring device main body) has water resistance (waterproofing) performance that complies with, for example, JIS standards. Further, the attachment/detachment portion of the sensor 10 in the measuring device 100 is configured so that liquid such as the test liquid does not flow into the inside of the measuring device 100 when the sensor 10 is attached.

FIG. 3 shows a block diagram of the measuring device 100 according to this embodiment. As shown in FIG. 3, the measuring device 100 includes a CPU (Central Processing Unit) 101a, a RAM (Random Access Memory) 101b, a storage section 101c, an input section 101d configured as, for example, a touch panel, a display, a touch panel type display, It is configured as a computer (smartphone, tablet, PC, etc.) including an output section (display section) 101e configured as a lamp, buzzer, etc., and a communication section 101f using wireless or wired communication. Note that the output unit 101e may be configured to also function as the input unit 101d by using a touch panel as a GUI (Graphical User Interface), for example. In this aspect, an example will be described in which the output section 101e also functions as the input section 101d. The CPU 101a, the RAM 101b, the storage section 101c, the input section 101d, the output section 101e, and the communication section 101f are configured to be able to exchange data with each other via the internal bus 101g.

The storage unit 101c is composed of a non-volatile memory device such as a flash memory or an HDD (Hard Disk Drive). The storage unit 101c is configured as a computer-readable recording medium. A control program for controlling the operation of the measuring device 100, a data file used for the operation, and the like are readably stored in the storage unit 101c. Hereinafter, the control program, data file, etc. will be collectively referred to as simply a program. The RAM 101b is configured as a memory area (work area) in which programs, data, etc. read by the CPU 101a are temporarily held.

When the CPU 101a executes the control program read from the storage unit 101c, the measuring device 100 has a detection function 100a, a selection function 100b, a determination function 100c, a preprocessing function 100d, a measurement function 100e, a calculation function 100f, and an energization test function 100g. , output function 100h, etc. are realized. These functions are realized by the cooperative operation of the above-mentioned program and hardware resources such as the CPU 101a, the RAM 101b, the storage section 101c, the input section 101d, the output section 101e, and the communication section 101f. Hereinafter, these functions realized by the measuring device 100 will be explained in order.

(Detection function)
The detection function 100a is configured to detect attachment and detachment (attachment and detachment) of the sensor 10 to the measurement device 100. Further, the detection function 100a is configured to record the attachment time (attachment date and time) of the sensor 10 upon detecting attachment of the sensor 10 to the measuring device 100, and store information on the attachment time in a readable manner in the storage unit 101c. has been done. Further, the detection function 100a may be configured to record the removal time of the sensor 10 when detecting the removal of the sensor 10 from the measuring device 100, and store information on the removal time in a readable manner in the storage unit 101c. good. Further, when the detection function 100a detects the attachment/detachment of the sensor 10, it operates an output function 100h, which will be described later, so as to output a message indicating that "detachment has been detected", information on the time of attachment, etc. to the output unit 101e. may be configured.

(selection function)
When the measurer inputs instructions such as the type of test substance to be measured this time through the input section 101d, the selection function 100b stores the information in advance in the storage section 101c in response to the command from the input section 101d. From among the multiple calibration curves, multiple pretreatment conditions, and multiple measurement conditions provided, the operator selects the calibration curve, pretreatment condition, and measurement condition that correspond to the test substance input. It is configured. The calibration curve, pretreatment conditions, and measurement conditions can be prepared according to the specifications of the sensor 10 used and the type of test substance that can be measured, and stored in advance in the storage unit 101c. Note that the "pretreatment conditions" in this specification are the conditions for performing the below-described pretreatment, such as the applied potential conditions when performing the pretreatment, the number of times the pretreatment is performed, and the like. Furthermore, "measurement conditions" in this specification are conditions for performing electrochemical measurements, which will be described later, such as applied voltage range conditions, sweep speed conditions, etc. when performing electrochemical measurements.

Further, the selection function 100b may be configured to allow the measurer to further select a measurement range when the approximate concentration of the test substance to be measured this time can be predicted. For example, the measuring person may be configured to be able to select measurement conditions, a calibration curve to be used, etc. in more detail.

Further, the selection function 100b is configured to readably store information input by the measuring person (information on the type of test substance, information on input date and time, etc.) in the storage unit 101c.

Further, the selection function 100b may be configured to operate an output function 100h, which will be described later, to output information on the selected calibration curve and measurement conditions to the output unit 101e.

(judgment function)
The determination function 100c is configured to determine whether preprocessing is necessary, specifically, whether at least one of the following conditions 1 to 4 applies.
(Condition 1) When LSV measurement is performed for the first time after the sensor 10 is attached to the measurement device 100 (Condition 2) LSV measurement is repeatedly performed using the same sensor 10 without removing the sensor 10 from the measurement device 100 In this case, when LSV measurement is performed after a predetermined period of time has elapsed from the time when the previous LSV measurement was performed (excluding cases where the preprocessing described below is performed after the previous LSV measurement).
(Condition 3) When the same sensor 10 is used without removing the sensor 10 from the measuring device 100, when LSV measurement is performed after a predetermined time has elapsed from the time when the last preprocessing was performed (however, when performing LSV measurement (Excluding cases where LSV measurement was performed after pretreatment)
(Condition 4) When LSV measurements are repeatedly performed using the same sensor 10 without removing the sensor 10 from the measurement device 100, the concentration of another test substance different from the test substance measured in the previous LSV measurement When performing LSV measurement of

For example, the determination function 100c determines (a) the time when the sensor 10 was attached to the measuring device 100, (b) the time when the previous LSV measurement was performed, and (c) the time when the previous (last) preprocessing was performed. Based on this, it is configured to determine whether at least one of (Condition 1) to (Condition 3) applies.

Specifically, the determination function 100c further has a function of reading the above-mentioned times (a) to (c) from the storage unit 101c, and extracting the most recent time among the times (a) to (c). Further, the determination function 100c is configured to determine that (condition 1) is satisfied when the latest time is time (a). Further, the determination function 100c further has a function of calculating the time from time (b) or (c) to the extraction time when the latest time is time (b) or (c). Further, the determination function 100c determines that the most recent time is time (b), and the time from time (b) to the time of extraction exceeds a predetermined time (for example, 2 hours, preferably 1 hour, more preferably 30 minutes). If so, it is determined that (Condition 2) is met. Further, the determination function 100c determines that the latest time is time (c), and the time from time (c) to the time of extraction exceeds a predetermined time (for example, 2 hours, preferably 1 hour, more preferably 30 minutes). If so, it is determined that (Condition 3) is satisfied.

In addition, the determination function 100c determines the type of test substance measured in the previous LSV measurement (hereinafter also referred to as "previous measurement substance") and the type of test substance measured in the current electrochemical measurement (hereinafter referred to as "previous measurement substance"). It is configured to determine whether (Condition 4) is satisfied based on information on the current measurement substance (also referred to as "current measurement substance").

For example, the determination function 100c is configured to read information on the previous measurement substance from the storage unit 101c and determine whether the information matches the current measurement substance. Further, the determination function 100c is configured to determine that (condition 4) is met if the previous measurement substance and the current measurement substance do not match.

If the determination function 100c determines that at least one of (Condition 1) to (Condition 4) applies, the determination function 100c issues a warning to the measurer that "pretreatment is necessary" (a function that prompts the implementation of pretreatment). )have. For example, when at least one of (Condition 1) to (Condition 4) applies, the determination function 100c uses the output function 100h, which will be described later, to display a message or issue an alarm urging implementation of preprocessing. configured to operate.

Further, the determination function 100c is configured to operate the energization test function 100g if it is determined that none of (Condition 1) to (Condition 4) apply.

In addition, the determination function 100c determines whether at least one of (Condition 1) to (Condition 4) is met, information on read times (a) to (c), information on the most recent time, information on the most recent The output function 100h, which will be described later, is configured to output information on the time when the time was extracted, information on the time from time (b) or (c) to the time when the most recent time was extracted, information on the substance to be measured last time, etc. to the output unit 101e. It may be configured to operate.

(Pre-processing function)
If the determination function 100c determines that at least one of (conditions 1) to (conditions 4) applies, the preprocessing function 100d performs the preprocessing a preset (defined) number of times (one or more times). It is configured as follows. Note that the number of times the preprocessing is performed is set in the preprocessing conditions stored in advance in the storage unit 101c. In this specification, "pretreatment" refers to pretreatment conditions corresponding to the test substance selected by the selection function 100b, with at least the working electrode 15 and the counter electrode 16 in contact with a treatment solution containing the test substance. Based on this, a potential exceeding the redox potential of the test substance (for example, O ₃ ) is applied to the working electrode 15 to cause an electrochemical reaction on the surface (detection surface) of the working electrode 15. The treatment liquid used in the pretreatment is preferably the same (similar) liquid as the test liquid used in the concentration measurement process described below, which is performed subsequent to the pretreatment. That is, when the test liquid is tap water containing O ₃ at a predetermined concentration, it is preferable that the treatment liquid is also tap water containing O ₃ at a predetermined concentration. Moreover, it is more preferable that the treatment liquid is a liquid sampled from a test liquid used in the concentration measurement process described below. In the following, an example in which the processing liquid is a liquid sampled from a test liquid will be described.

Further, the pretreatment function 100d is configured to perform the above-mentioned pretreatment and measure the value of the current flowing between the working electrode 15 and the counter electrode 16 due to the electrochemical reaction occurring in the pretreatment. Good too. In addition, the preprocessing function 100d automatically determines whether to re-execute the preprocessing according to the rate of change in the measured current value and the presence or absence of a current peak, and varies the number of times the preprocessing is performed. may be configured.

Furthermore, even if the determination function 100c determines that none of (Condition 1) to (Condition 4) apply, the preprocessing function 100d is configured to accept preprocessing instructions from the measurer via the input unit 101d. When an instruction is received, it may be configured to perform preprocessing in response to a command from the input unit 101d.

Further, the preprocessing function 100d is configured to record the execution time of the preprocessing and store this time information in a readable manner in the storage unit 101c. The "preprocessing implementation time" here can be the "preprocessing start time" or the "preprocessing completion time," and is more preferably the "preprocessing completion time."

The preprocessing function 100d also controls an output function 100h, which will be described later, to output a message indicating that "preprocessing has been completed", information on the execution time of the preprocessing, etc. to the output unit 101e when the preprocessing is completed. It may be configured to operate.

Note that the concentration of the test substance to be measured is likely to have changed in the treatment liquid used for pretreatment, so before performing the concentration measurement process described below, replace the treatment liquid with a new test liquid. Needs to be replaced. For this reason, it is preferable that the preprocessing function 100d has a function of issuing a warning to the measurer that "the test liquid needs to be replaced" after the preprocessing is completed. For example, it is preferable that the preprocessing function 100d is configured to operate an output function 100h, which will be described later, to display a message or issue an alarm to prompt replacement of the test liquid when the preprocessing is completed.

(Electricity test function)
The energization test function 100g is configured to perform an energization test before the measurement function 100e performs the LSV measurement, preferably immediately before the LSV measurement. Note that the term "current test" in this specification refers to checking the connection between the measuring device 100 and the sensor 10, or checking the presence or absence of dirt or deterioration on the surface of each electrode 15 to 17 of the sensor 10. It is a test to For example, the energization test function 100g is configured to measure the energization resistance (resistivity) between arbitrary electrodes using the AC two-electrode method with the electrode group 30 in contact with a test liquid or the like. The current conduction resistance between any electrodes is, for example, within the range of a minute voltage before an electrochemical reaction occurs on the surface of the working electrode 15 (for example, within the range of 0.01V to 0.1V when the test substance is _O3 ). It is preferable to measure by applying an alternating current voltage (sin wave) of a predetermined frequency between arbitrary electrodes and measuring the impedance between arbitrary electrodes. This makes it possible to prevent the test substance in the test liquid from being consumed by the current test, especially by measuring the current resistance within the range of a minute voltage before an electrochemical reaction occurs on the surface of the working electrode 15. .

The energization test function 100g is preferably configured to perform the energization test before (preferably immediately before) the LSV measurement, but it is preferable that the energization test is performed before the determination function 100c performs the determination process. may be configured.

Further, the energization test function 100g may be configured to operate an output function 100h, which will be described later, so as to output the measured energization resistance value to the output section 101e.

Further, the energization test function 100g is configured to operate the measurement function 100e when the measured energization resistance is less than or equal to a predetermined value set in advance.

In addition, the energization test function 100g has a function that issues a warning to the measurer that "maintenance or replacement of the sensor 10 is required" if the measured energization resistance exceeds a preset value. may have. For example, the energization test function 100g may be configured to operate an output function 100h, which will be described later, to display a message or issue an alarm to prompt maintenance of the sensor 10 or replacement of the sensor 10. Note that "maintenance of the sensor 10" in this specification includes cleaning the sensor 10 and cleaning the electrode contacts.

(Electrochemical measurement function)
The electrochemical measurement function 100e (hereinafter also simply referred to as the "measurement function 100e") performs LSV measurement (electrochemical measurement) and measure the concentration of the test substance. For example, the measurement function 100e determines the distance between the working electrode 15 and the counter electrode 16 based on the measurement conditions corresponding to the test substance selected by the selection function 100b, with at least the electrode group 30 in contact with the test liquid. By applying a voltage to the electrode and sweeping the potential of the working electrode 15 based on the potential of the reference electrode 17, an electrochemical reaction is caused on the surface of the working electrode 15. It is configured to electrochemically measure the value of the current flowing between the electrode 15 and the counter electrode 16, which corresponds to the concentration of the test substance.

Further, the measurement function 100e is configured to record data on the measured current value and the time at which the electrochemical measurement was performed, and to readably store this information in the storage unit 101c. The "time at which electrochemical measurement is performed" here can be defined as "time at which electrochemical measurement is started" or "time at which electrochemical measurement is completed."

Further, the measurement function 100e may be configured to operate an output function 100h, which will be described later, so as to output data on the measured current value and information on the recorded time to the output unit 101e.

In addition, after the determination function 100c issues a warning indicating that "preprocessing is necessary", the measurement function 100e performs the preprocessing until the preprocessing function performs the preprocessing one or more times, or a predetermined number of times. It may further have a function of not performing LSV measurement until then.

(calculation function)
The calculation function 100f is configured to calculate the concentration of the test substance from (the peak value of) the current value measured by the measurement function 100e using the calibration curve selected by the selection function 100b. Further, the calculation function 100f may be configured to readably store the calculated concentration data in the storage unit 101c. Further, the calculation function 100f may be configured to operate an output function 100h, which will be described later, so as to output the calculated concentration data to the output unit 101e.

(output function)
The output function 100h outputs to the output unit 101e a message requesting the measurer to input an instruction to start measurement and perform preprocessing (input an instruction to start preprocessing (command for operating the preprocessing function 100d)). It is configured in such a way that it is possible.

Further, the output function 100h is configured to be able to output a warning from the determination function 100c, a warning from the preprocessing function 100d, and a warning from the energization test function 100g to the output unit 101e. The output function 100h also includes information on the attachment/detachment of the sensor 10 detected by the detection function 100a, information on the calibration curve, preprocessing conditions, and measurement conditions selected by the selection function 100b, information on the determination result by the determination function 100c, and information on the determination result by the determination function 100c. It is configured such that information on the current value measured by the energizing current value measured by the calculation function 100e, information on the concentration of the test substance calculated by the calculation function 100f, etc. can be read from the storage unit 101c and output (displayed) on the output unit 101e. There is.

Further, the output function 100h may be configured to be able to display a message prompting preparation for measurement. For example, the output function 100h may be configured to output a message to the output unit 101e prompting the preparation of a test liquid to be measured and the setting of the sensor 10. Note that "a set of sensors 10" in this specification means that at least the electrode group 30 of the sensor 10 attached to the measuring device 100 is brought into contact with the test liquid (or treatment liquid).

Further, the output function 100h may be configured to be able to display a message prompting re-preparation for measurement after performing pre-processing or after maintenance or replacement of the sensor 10. For example, the output function 100h may be configured to output a message to the output unit 101e that prompts replacement of the test liquid or reset of the sensor 10.

In addition, the output function 100h includes a message requesting the measurer to input a command to "confirm that the sample liquid has been replaced immediately" before displaying a message requesting input of a command to start measurement. may be configured to be output to the output unit 101e.

In addition, when measuring the concentration of a test substance in a test liquid whose concentration decreases over time, such as ozonated water, the measurement function 100e can be used immediately after sampling the test liquid. It is preferable to start LSV measurement. For this reason, the output function 100h may be configured to be able to display a message or issue an alarm immediately before the measurement function 100e performs the LSV measurement. .

(3) Electrochemical measurement method Next, using the above-mentioned measuring device 100, the O ₃ concentration in a test liquid containing O ₃ as a test substance at a predetermined concentration is measured, specifically, using tap water as raw water. An example of a method for measuring the dissolved ozone concentration in ozone water produced using a commercially available ozone water generator will be described with reference to FIGS. 4 and 5. In the following description, various functions such as the determination function 100c, the preprocessing function 100d, and the measurement function 100e are realized by reading out programs stored in the storage unit 101c and executing them by the CPU 101a.

(Setting of calibration curve, pretreatment conditions, and measurement conditions)
As shown in FIG. 4, first, a calibration curve, pretreatment conditions, and measurement conditions are set (setting of calibration curve, etc.). Specifically, the measurer inputs the type of test substance to be measured via the input section 101d. When a test substance is input by the measurer, the selection function 100b selects a plurality of calibration curves and a plurality of pre-processings stored in advance in the storage unit 101c based on the information of the test substance input by the measurer. A calibration curve, pretreatment conditions, and measurement conditions are each set (selected) according to the test substance from among the conditions and a plurality of measurement conditions. In addition, when the approximate concentration of the test substance in the test liquid can be predicted, the measurer may further select the measurement range and select the measurement conditions and the calibration curve to be used in more detail. . Further, the selection function 100b stores information (information on the type of test substance, information on input date and time, etc.) inputted by the measuring person via the input unit 101d in a readable manner in the storage unit 101c. At this time, the selection function 100b may operate the output function 100h so as to output information on the selected calibration curve, preprocessing conditions, and measurement conditions to the output unit 101e.

(Installation of sensor)
A measuring person attaches the sensor 10 to the measuring device 100. When the detection function 100a detects attachment of the sensor 10 to the measurement device 100, it stores information on the attachment time of the sensor 10 to the measurement device 100 in the storage unit 101c in a readable manner. At this time, the detection function 100a may operate the output function 100h so as to output a message or the like indicating that "wearing of the sensor 10 has been detected" to the output unit 101e. Additionally, information such as a serial number is attached to the sensor 10 using a bar code, a two-dimensional code, etc., and when the sensor 10 is attached to the measuring device 100, the information regarding the attached sensor 10 can be read by the measuring device 100. The data may be readably stored in the storage unit 101c.

Note that the sensor 10 may be attached at any timing before, after, or during (simultaneously with) setting of the calibration curve, etc.

(Preparation for measurement)
After setting of the calibration curve and the like and mounting of the sensor 10 are completed, the output function 100h outputs a message urging preparation for measurement to the output unit 101e. When a message prompting preparation for measurement is displayed, the measurer samples the test liquid (preparation of the test liquid), and as shown in FIG. 5, attaches the electrode group 30 of the sensor 10 to the sampled test liquid. contact (setting of sensor 10).

After displaying a message urging preparation for measurement, the output function 100h outputs a message requesting the measurer to input an instruction to start measurement to the output unit 101e. When a message requesting input of a command to start measurement is displayed, the measurer inputs an instruction to start measurement via the input unit 101d.

(Determination process)
When an instruction to start measurement is received from the measurement person via the input unit 101d, the determination function is activated while keeping the electrode group 30 in contact with the test liquid (without removing the electrode group 30 from the test liquid). 100c determines whether preprocessing is necessary in response to a command from input unit 101d. That is, the determination function 100c determines whether at least one of the above-mentioned (Condition 1) to (Condition 4) is met.

Specifically, the determination function 100c reads the above-mentioned times (a) to (c) from the storage unit 101c, and extracts (determines) the most recent time among the times (a) to (c). Then, the determination function 100c determines that (condition 1) is met when the latest time is (a). If the latest time is (b), the determination function 100c further calculates the time from the time (b) to the time of extraction, and if the calculated time exceeds a predetermined time, it determines that (condition 2) is met. judge. Further, when the latest time is (c), the determination function 100c further calculates the time from the time of (c) to the time of extraction, and if the calculated time exceeds a predetermined time, (condition 3) is applied. It is determined that this applies.

Further, the determination function 100c reads out information on the previous measurement substance from the storage unit 101c, and determines whether the information matches the current measurement substance. The determination function 100c determines that (condition 4) is met if these measurement substances do not match.

If the determination function 100c determines that at least one of (Condition 1) to (Condition 4) applies, it issues a warning to the measurer indicating that "pre-processing is required" as a determination result. For example, the determination function 100c operates the output function 100h to display a message or issue an alarm to prompt implementation of preprocessing. Note that even if one of (Condition 1) to (Condition 3) and (Condition 4) apply, the determination function 100c issues a warning indicating that "preprocessing is required." It is only necessary to issue the message to the person taking the measurement once. Further, the output function 100h outputs a message requesting the measurer to perform pre-processing to the output unit 101e, following the warning that "pre-processing is required".

If the determination function 100c determines that none of (Condition 1) to (Condition 4) apply, that is, if it determines that "preprocessing is unnecessary", the determination function 100c performs the preprocessing described below. The energization test function 100g is activated so that the energization test is performed without performing the energization test.

(Preprocessing)
When a message requesting the implementation of pretreatment is displayed, the measurer, while keeping the electrode group 30 in contact with the test liquid (without removing the electrode group 30 from the test liquid), presses the input unit 101d. Input instructions to start preprocessing via . When receiving an instruction to start preprocessing from the measurement person via the input unit 101d, the preprocessing function 100d performs the above-mentioned preprocessing a specified number of times in response to the command from the input unit 101d. Note that even if the determination function 100c determines that none of (Condition 1) to (Condition 4) apply, the preprocessing function 100d accepts the preprocessing request from the measurer via the input unit 101d. Upon receiving the instruction, the preprocessing function 100d may perform the above-mentioned preprocessing a specified number of times in response to a command from the input unit 101d.

As the treatment liquid used for pretreatment, the test liquid prepared for measurement can be used as is. Therefore, when inputting an instruction to start pretreatment, the electrode group 30 of the sensor 10 may remain in contact with the test liquid prepared for concentration measurement.

The preprocessing function 100d stores the time at which the preprocessing was performed in a readable manner in the storage unit 101c. At this time, the preprocessing function 100d may operate the output function 100h so as to output the time at which the preprocessing was performed to the output unit 101e.

By performing such pretreatment, the surface (detection surface) of the working electrode 15 is changed to a surface suitable for LSV measurement, for example, a surface suitable for detection of the substance to be measured (i.e., O ₃ ), and the sensor 10 sensitivity can be restored. That is, the surface of the working electrode 15 changes depending on the history of the sensor 10 (storage conditions, elapsed time since surface treatment, etc.) after surface treatment during electrode manufacturing (before shipping), and the surface of the sensor 10 changes. Even if the sensitivity decreases, by performing the above-mentioned pretreatment, the surface of the working electrode 15 can be changed to a surface suitable for measuring the current measurement substance, and the sensitivity of the sensor 10 can be restored. . Thereby, concentration measurement processing (LSV measurement), which will be described later, can be performed using the sensor 10 in a highly sensitive state.

Note that "recovering the sensitivity of the sensor 10" refers to increasing the sensitivity of the sensor 10 to a sensitivity close to the sensitivity immediately after surface treatment was performed on the working electrode 15 during electrode manufacture (for example, the saturated sensitivity of the sensor 10). It means to raise again.

Preferably, the pretreatment is performed continuously a predetermined number of times (preferably multiple times, more preferably three or more times). Thereby, the surface of the working electrode 15 can be reliably changed to a surface suitable for detecting the current measurement substance, and the sensitivity of the sensor 10 can be reliably restored.

By performing the pretreatment even once, the surface of the working electrode 15 can be changed to a surface suitable for detecting the substance to be measured this time, and the sensitivity of the sensor 10 can be restored to some extent. However, by performing the pretreatment multiple times, the surface of the working electrode 15 can be reliably changed to a surface suitable for detecting the substance to be measured this time, and the sensitivity of the sensor 10 can be reliably restored. For this reason, it is preferable to perform the pretreatment multiple times.

Note that the preprocessing may be performed a predetermined number of times, and the measurer may be asked to perform the preprocessing again, or may be set to be performed a predetermined number of times. Further, the pretreatment function 100d performs the pretreatment and measures the current value (for example, O ₃ reduction current value) flowing between the working electrode 15 and the counter electrode 16 due to the electrochemical reaction occurring in the pretreatment. However, the number of times the preprocessing is performed may be varied by automatically determining whether to perform the preprocessing again depending on the rate of change in the current value or the presence or absence of a current peak.

When the pretreatment is performed, the test substance present around the electrode group 30 is gradually consumed as the electrochemical reaction progresses, and is eventually exhausted. For this reason, it is preferable to perform the pretreatment while the treatment liquid is flowing with respect to the electrode group 30. When performing pretreatment multiple times with the treatment solution still, replace the treatment solution each time you perform pretreatment, or perform the next pretreatment after one pretreatment is completed. It is preferable to stir the treatment solution before carrying out the treatment. As a result, the surface of the working electrode 15 can be reliably changed to a surface suitable for detecting the current measurement substance, and the sensitivity of the sensor 10 can be reliably restored.

Preferably, the treatment liquid used in the pretreatment is the same liquid as the test liquid used in the concentration measurement process described below, which is performed following the pretreatment, so that sampling from the test liquid used in the concentration measurement process described later is preferable. By using such a liquid, the surface of the working electrode 15 of the sensor 10 can be reliably changed to a surface suitable for measuring the concentration of the substance to be measured this time. Further, when the test substance is O ₃ , it is more preferable that the treatment liquid contains O ₃ at a concentration of, for example, 0.1 ppm or more. Thereby, the surface of the working electrode 15 can be changed more reliably to a surface suitable for measuring the concentration of dissolved ozone.

After the preprocessing is completed, the preprocessing function 100d may operate the output function 100h to output a message or the like indicating that "preprocessing has been completed" to the output unit 101e.

By performing pretreatment, the test substance in the test solution (processing solution) is consumed and the concentration of the test substance in the test solution changes. Before performing the concentration measurement process, it is necessary to replace the processing liquid with a new test liquid for concentration measurement. Therefore, after the preprocessing is completed, the preprocessing function 100d issues a warning to the measurer indicating that "the test liquid needs to be replaced." For example, the preprocessing function 100d operates the output function 100h to display a message or issue an alarm to prompt replacement of the test liquid.

(Re-preparation for measurement)
The output function 100h outputs a message urging re-preparation for measurement to the output unit 101e, following the warning that "the test liquid needs to be replaced." When a message urging re-preparation for measurement is displayed, the measurer replaces the processing liquid with a new test liquid (test liquid replacement) and replaces at least the electrode group 30 of the sensor 10 attached to the measuring device 100. Contact with the subsequent test liquid (resetting the sensor 10).

Further, when the test liquid is replaced and the sensor 10 is reset, a predetermined time may have passed since the pretreatment was performed, or not only the test liquid but also the sensor 10 may have been replaced. For this reason, it is preferable that the output function 100h outputs a message requesting the measurer to input an instruction to start measurement to the output unit 101e again, following the message requesting re-preparation for measurement. When a message requesting input of a command for instructing to start measurement is displayed, the measurer inputs a command for instructing to start measurement. When an instruction to start measurement is received from the measurement person via the input unit 101d, the determination function is activated while keeping the electrode group 30 in contact with the test liquid (without removing the electrode group 30 from the test liquid). 100c performs the above-described determination process again.

(Electricity test)
When the determination function 100c determines that "pre-processing is unnecessary", the determination function 100c operates the energization test function 100g, as described above. While maintaining the electrode group 30 in contact with the test liquid (without removing the electrode group 30 from the test liquid), the current conduction test function 100g performs a current conduction test to measure the current conduction resistance between arbitrary electrodes. do. At this time, the energization test function 100g may operate the output function 100h so as to output the measured energization resistance value to the output section 101e.

If the measured energization resistance is less than or equal to a predetermined value, the energization test function 100g operates the measurement function 100e to perform concentration measurement processing. In addition, if the current carrying resistance value is extremely low (near zero), there is a possibility that the circuit is short-circuited, so the current carrying test function 100g will display an error message ("Sensor 10 needs to be checked"). The output function 100h may be operated to display a message).

If the measured current carrying resistance exceeds a predetermined value, there is a possibility that one of the wirings 12 to 14 is disconnected (there is a possibility that there is no electrical connection between the measuring device 100 and the sensor 10), or the sensor There is a possibility that the surface of at least one of the electrodes 15 to 17 included in the electrode 10 is dirty. Therefore, if the current conduction resistance exceeds a predetermined value, the current conduction test function 100g issues a warning to the measurer indicating that "maintenance or replacement of the sensor 10 is required." For example, the energization test function 100g operates the output function 100h to display a message or issue an alarm to prompt maintenance or replacement of the sensor 10. When a message prompting maintenance or replacement of the sensor 10 is displayed, the measurer performs maintenance on the sensor 10 or replaces the sensor 10 with a new (other) sensor 10.

After displaying a message prompting maintenance or replacement of the sensor 10, the output function 100h outputs a message requesting the measurer to input a command to the effect that "maintenance or replacement of the sensor 10 has been completed" to the output unit 101e. . When the maintenance or replacement of the sensor 10 is completed, the measurer inputs a command to the effect that "maintenance or replacement of the sensor 10 has been completed."

After confirming the input of a command from the measurement person stating that "maintenance or replacement of the sensor 10 has been completed," the output function 100h outputs a message urging re-preparation for measurement to the output unit 101e. The measurement re-preparation procedure performed after maintenance or replacement of the sensor 10 can be similar to the measurement re-preparation procedure described above that is performed after performing pre-processing. Furthermore, when re-preparing for measurement after maintenance or replacement of the sensor 10, a message requesting the measurer to input an instruction to start measurement is again output to the output unit 101e, following a message prompting re-preparation for measurement. It is preferable. When a message requesting input of a command to instruct to start measurement is displayed, the measurer inputs a command to instruct to start measurement, and in response to the command from the input unit 101d, the determination function 100c performs the above-described determination process. Execute again.

(Concentration measurement processing)
If the current conduction resistance measured in the current conduction test is less than or equal to a predetermined value, the current conduction test function 100g operates the measurement function 100e, as described above. The measurement function 100e then performs a process of electrochemically measuring the O ₃ concentration in the test liquid (concentration measurement process). In the concentration measurement process, an electrochemical measurement step and a concentration calculation step are performed in order.

Note that the concentration measurement process is preferably carried out within a predetermined time (for example, within 2 hours, preferably within 1 hour, more preferably within 30 minutes) after the pretreatment is completed. Thereby, the LSV measurement can be performed while the sensitivity of the sensor 10 is high, that is, before the sensitivity of the sensor 10 decreases again, and the O ₃ concentration can be measured with high accuracy.

<Electrochemical measurement step>
When the measurement function 100e is operated, the measurement function 100e performs LSV measurement. For example, the measurement function 100e applies a voltage between the working electrode 15 and the counter electrode 16 by controlling the applied voltage to each electrode of the sensor 10, and applies the voltage to the working electrode based on the potential of the reference electrode 17. LSV measurement is performed by sweeping the potential of 15 and measuring the value of the current flowing between the working electrode 15 and the counter electrode 16 at that time. Then, the measurement function 100e stores the measured current value together with the measurement time (the time at which the LSV measurement is performed) in the storage unit 101c in a readable manner. At this time, the measurement function 100e may operate the output function 100h so as to output the measured current value and the measurement time to the output unit 101e.

Note that the test liquid used in this step (concentration measurement process) can be the same as the test liquid used in the energization test. Note that the sequence may be interrupted after the energization test is completed, and the test liquid may be replaced with a newly sampled test liquid.

LSV measurement is performed with the electrode group 30 in contact with the test liquid in a stationary state. In this specification, "the static state of the test liquid" means "the degree of electrochemical reaction occurring on the surface of the working electrode 15 is determined by the amount of O ₃ that diffuses through the test liquid and reaches the surface of the electrode group 30". ``a state in which one is substantially controlled by a person.'' When LSV measurement is started with the test liquid in a stationary state, the applied current gradually increases as the voltage is applied, and then the O ₃ present around the electrode group 30 increases as the electrochemical reaction progresses. The O ₃ concentration is gradually determined by the amount of O ₃ consumed in the electrode group 30 and the amount of O ₃ supplied by diffusion from the periphery of the electrode group 30. The current will change to correspond to the current. Therefore, in a graph (voltammogram) obtained by plotting the applied current values, a predetermined peak corresponding to the O ₃ concentration of the test liquid appears as time passes after the start of LSV measurement. Note that if you start LSV measurement when the test liquid is not stationary (the test liquid is flowing), the test liquid around the electrode group 30 will be replaced and O ₃ will flow around the electrode group 30. will be newly added. Therefore, the applied current does not decrease, and a predetermined peak no longer appears in a graph obtained by plotting the applied current values.

As described above, if at least one of (Condition 1) to (Condition 4) applies, preprocessing is performed before performing LSV measurement. Therefore, it is possible to perform LSV measurement using the sensor 10 in a highly sensitive state. This makes it possible to detect O ₃ in the test liquid with high sensitivity. As a result, for example, in a voltammogram obtained by LSV measurement, a current peak corresponding to the O ₃ concentration (for example, a peak of O ₃ reduction current) can be reliably observed.

In this specification, "a current peak is observed in the voltammogram" means that in the voltammogram, there is a top that protrudes convexly toward either the positive side or the negative side. When a BDD electrode is used as the reference electrode and the test liquid is a liquid containing O ₃ , the potential of the working electrode 15 is changed from the potential of the reference electrode 17 with the electrode group 30 in contact with the test liquid in a stationary state. In the voltammogram obtained when performing LSV measurement at a predetermined speed (for example, 0.1 V/sec), the current peak is, for example, between -0.3 V and -0.9 V (vs. reference electrode 17). observed within the potential range.

<Concentration calculation step>
Once the electrochemical measurement step is completed, the measurement function 100e operates the calculation function 100f to calculate the O ₃ concentration. Then, the calculation function 100f uses the calibration curve selected by the selection function 100b to calculate the concentration of O ₃ in the test liquid from (the peak value of) the current value measured by the measurement function 100e. The calculation function 100f also operates the output function 100h to output the calculated O ₃ concentration data to the output unit 101e. At this time, the calculation function 100f may store the calculated O ₃ concentration together with the calculation date and time in the storage unit 101c so as to be readable.

(repeated measurement)
After the concentration measurement process is completed, the test liquid may be replaced and a new concentration measurement process may be performed without removing the sensor 10 from the measurement device 100. In this case, the setting of a calibration curve, preparation for measurement, determination processing, pretreatment if necessary, and concentration measurement processing are repeatedly performed in this order. Note that this set may include an energization test.

(Removal of sensor)
After the concentration measurement process is completed, the person measuring the sensor 10 may remove the sensor 10 from the measuring device 100. When the detection function 100a detects the removal of the sensor 10 from the measurement device 100, it may operate the output function 100h so as to output a message or the like indicating that "removal of the sensor 10 has been detected" to the output unit 101e. . Further, the detection function 100a may readably store information on the time when the sensor 10 is removed from the measuring device 100 in the storage unit 101c.

(4) Effects According to this aspect, one or more of the following effects can be obtained.

(a) If at least one of the above (conditions 1) to (conditions 4) is met, preprocessing is performed before performing LSV measurement. This makes it possible to perform LSV measurement using the sensor 10 in a highly sensitive state. As a result, the concentration of the test substance in the test liquid, especially when the test substance is O ₃ , can be detected with high sensitivity, and the concentration of the test substance can be calculated with high precision and good reproducibility.

(b) The processing liquid used in the pretreatment is the same as the test liquid used in the LSV measurement, preferably a liquid sampled from the test liquid used in the LSV measurement, and the working electrode is 15 can be reliably changed to a surface suitable for electrochemical measurements.

(c) In the concentration measurement process, when measuring the concentration of dissolved ozone in ozone water prepared using water as raw water, the treatment liquid used in the pretreatment contains _O3 at a concentration of 0.1 ppm or more. can be reliably changed to a surface suitable for measuring dissolved ozone concentration.

(d) By performing pretreatment as necessary before performing LSV measurement, even if the working electrode 15, counter electrode 16, and reference electrode 17 are all composed of BDD electrodes, , the current peak can be reliably observed in the voltammogram obtained by LSV measurement. As a result, when the test substance is ozone, even if the reference electrode is a BDD electrode, the fluctuation in potential becomes small, and the concentration of the test substance can be measured (calculated) with high precision and good reproducibility.

(e) A calibration curve, pretreatment conditions, and measurement conditions are prepared for each type of test substance that can be measured, and stored in advance in the storage unit 101c. Then, the selection function 100b selects a plurality of calibration curves, a plurality of preprocessing conditions, and a plurality of The calibration curve, pretreatment conditions, and measurement conditions according to the test substance are selected from among the measurement conditions. As a result, by performing preprocessing before performing LSV measurement, it becomes possible to continuously measure a wide variety of test substances with the same sensor 10. For example, after one sensor 10 is attached to the measuring device 100 and an electrochemical measurement of O ₃ concentration is performed, the chlorine concentration is continuously measured without removing the sensor 10 from the measuring device 100. It becomes possible to implement the following.

(f) Since the pretreatment of this embodiment is carried out within the electrochemical measurement system, there is no need to separately prepare a system for carrying out the pretreatment.

(g) Since the energization test of this embodiment is automatically carried out prior to the concentration measurement process of the test substance, there may be a connection failure between the measuring device 100 and the sensor 10, an initial failure of the sensor 10, etc. Problems such as dirt and deterioration on the surfaces of the electrodes 15 to 17 can be reliably detected. As a result, the inclusion of abnormal values due to poor measurement can be avoided.

(h) By using the measuring device 100 of this embodiment, maintenance and replacement of the sensor 10 and pretreatment of the sensor 10 can always be performed at appropriate timing. As a result, it becomes possible to always measure the concentration of the test substance in the test liquid with high accuracy and good reproducibility, regardless of the skill of the measurer.

(5) Modifications This aspect can be modified as in the following modifications. In addition, in the following description of the modified example, the same reference numerals are given to the same components as in the above-mentioned aspect, and the description thereof will be omitted. Moreover, the above-mentioned aspects and the following modified examples can be arbitrarily combined.

(Modification 1)
For example, the concentration measurement process may be a process for creating a calibration curve.

In this modification, the measuring device 100 further has a calibration curve creation function. The calibration curve creation function is configured to create a calibration curve showing the correlation between the current value and the concentration of the test substance based on the (peak value) of the current value measured by the measurement function 100e.

In this modification, a measurer attaches the sensor 10 to the measuring device 100, similarly to the above-described embodiment. Once the sensor 10 has been installed, similarly to the above-described embodiment, setting of a calibration curve, determination processing, pre-processing if necessary, energization test, and concentration measurement processing are performed in this order. In this modification, when performing the concentration measurement process, a liquid (standard solution) in which the concentration of the test substance is known is prepared as the test liquid. Furthermore, in this modification, the selection function 100b does not need to select a calibration curve. Other procedures and conditions in each of the above-mentioned treatments and tests can be the same as those in each of the treatments and tests in the above embodiments.

In this modification, a set of determination processing, preprocessing, and concentration measurement processing is repeated a predetermined number of times while changing the standard solution (the concentration of the test substance in the standard solution). Note that this set may include the setting of a calibration curve, etc., and the energization test.

After repeating a set including at least a determination process, a preprocess, and a concentration measurement process a predetermined number of times, the calibration curve creation function performs Create a calibration curve showing the correlation between the current value and the concentration of the test substance.

Note that the calibration curve creation function may be configured to create a simple calibration curve connecting the measurement point and the origin using only the current value measured using one standard solution.

Also in this modification, if at least one of (Condition 1) to (Condition 4) applies, LSV measurement is performed using the sensor 10 in a high sensitivity state by performing preprocessing. becomes possible. Thereby, an accurate calibration curve can be created, and as a result, errors are less likely to occur in the concentration of the test substance calculated using the calibration curve.

By performing LSV measurement using the sensor 10 in a highly sensitive state, the current peak can be reliably observed in the obtained voltammogram. As a result, an accurate calibration curve can be created based on the measured current peak value. The present inventors have determined that the current peak value obtained by LSV measurement using the sensor 10 in which all of the electrodes 15 to 17 are BDD electrodes has a constant relationship with the O ₃ concentration in the test liquid. It has been confirmed that there is a correlation.

(Modification 2)
Further, for example, the concentration measurement process may be a process for calibration.

In this modification, the measuring device 100 further has a calibration function. The calibration function calculates a correction coefficient for comparison with past measured values based on the current value (peak value) measured by the measurement function 100e and the concentration of the test substance calculated by the calculation function 100f. is configured to do so. Further, in this modification, the calculation function 100f may be configured to take the calculated correction coefficient into consideration when calculating the concentration of the test substance.

In this modification, a measurer attaches the sensor 10 to the measuring device 100, similarly to the above-described embodiment. Once the sensor 10 has been installed, similarly to the above-described embodiment, setting of a calibration curve, determination processing, pre-processing if necessary, energization test, and concentration measurement processing are performed in this order. In this modification, when performing the concentration measurement process, a liquid (standard solution) in which the concentration of the test substance is known is prepared as the test liquid. Further, in this modification, the selection function 100b selects a past calibration curve of the same substance. Other procedures and conditions in each of the above-mentioned treatments and tests can be the same as those in each of the treatments and tests in the above embodiments.

After setting the calibration curve, judgment processing, pre-processing as necessary, energization test, and concentration measurement processing, the calibration function calculates the energization current corresponding to the concentration of the test substance in the standard solution measured by the measurement function 100e. A correction coefficient is calculated from the value (the peak value) and the current value based on the past calibration curve corresponding to the same concentration. The correction coefficient can be calculated by calculating the coefficient by comparing the slope of the simple calibration curve mentioned above with the slope of the past calibration curve, or by calculating the coefficient by comparing the measured current value and the past exposure to the same concentration. An example is a method (zero point adjustment) of comparing the applied current value measured with a test solution and assuming that the slope of the calibration curve does not change and determining a constant for adjustment.

Once the correction coefficient has been calculated (after the correction coefficient has been determined), prepare a new test liquid to be measured, and perform the following steps in the same way as above: setting the calibration curve, attaching the sensor, preparing for measurement, processing the judgment, etc. as necessary. Accordingly, pretreatment, energization test, and concentration measurement processing are performed to measure the concentration of the test substance in the test liquid. At this time, when calculating the concentration of the test substance in the concentration calculation step, the calculation function 100f calculates the concentration of the test substance using the calculated correction coefficient, and calculates the corrected concentration of the test substance in the test liquid. The concentration of the test substance. Further, the calculation function 100f may operate the output function 100h so as to output only the corrected concentration to the output unit 101e as data on the calculated concentration of the test substance. The output function 100h may be operated to output to the output unit 101e. The procedures and conditions for each of the other treatments and tests can be the same as those for each treatment and test in the above embodiment. Thereby, even if the sensitivity of the sensor 10 changes due to replacement of the sensor 10 or the like, it becomes easy to compare with past measured values. It also becomes possible to compare and examine data on multiple concentrations of the same test substance measured using different sensors 10.

Also in this modification, if at least one of (Condition 1) to (Condition 4) applies both during calibration and measurement, the sensor 10 in a highly sensitive state is used by performing preprocessing. It becomes possible to perform LSV measurement using Thereby, calibration and measurement can be performed accurately, and as a result, errors are less likely to occur in the concentration of the test substance calculated by the calculation function 100f. That is, it becomes possible to calculate the concentration of the test substance with higher accuracy.

(Modification 3)
In the above-described aspect, when the measuring person inputs the type of test substance to be measured this time through the input section 101d, the selection function 100b selects the selection function according to the command from the input section 101d. Although an example has been described in which the calibration curve, preprocessing conditions, and measurement conditions corresponding to the test substance input by the measurer are selected, the present invention is not limited thereto. For example, the measurement device 100 may be configured to perform only electrochemical measurements of a specific substance (eg, O ₃ ).

In this modification, only the calibration curve, preprocessing conditions, and measurement conditions that correspond to a predetermined test substance need be stored in the storage unit 101c. Therefore, in this modification, the measuring device 100 does not need to have the selection function 100b.

In this modification, a measurer attaches the sensor 10 to the measuring device 100, similarly to the above-described embodiment. Once the sensor 10 has been installed, similarly to the above-described embodiment, the following processes and tests are performed in order: determination processing, pre-processing if necessary, energization test, and concentration measurement processing. In the determination processing of this modification, the determination function 100c may determine whether at least one of the above-mentioned (conditions 1) to (conditions 3) is applicable. That is, it is not necessary to determine whether or not the above-mentioned (condition 4) is met. If the determination function 100c determines that at least one of the above conditions (condition 1) to (condition 3) is met, the preprocessing function 100d performs preprocessing. Other procedures and conditions in each of the above-mentioned treatments and tests can be the same as those in each of the treatments and tests in the above-described embodiments and modifications.

Also in this modification, if at least one of (Condition 1) to (Condition 3) applies, LSV measurement can be performed using the sensor 10 in a highly sensitive state by performing preprocessing. It becomes possible. Thereby, concentration calculation, preparation of a calibration curve, and calibration can be performed accurately, and effects similar to those of the above-mentioned embodiment and the above-described modification can be obtained.

(Modification 4)
In the above embodiments and modifications, an energization test may be further performed after the concentration measurement process is completed, preferably immediately after the concentration measurement process is completed. For example, an energization test may be further performed after (immediately) the electrochemical measurement step is completed. By further carrying out the energization test at this timing, it becomes possible to confirm whether or not the electrochemical measurement was performed normally.

(Modification 5)
For example, the measurement device 100 measures the concentration of a test substance in a test liquid sampled from the same test liquid using a plurality of different sensors 10, and compares the measurement results. It may also have a function of determining the correlation of sensor sensitivities between 10 sensors. For example, when replacing the sensor 10, the concentration of the test substance in the test liquid sampled from the same test liquid is measured using the sensor 10 before and after replacement, and the correlation between the sensor sensitivities before and after replacement is determined. You can do it like this.

(Modification 6)
The electrochemical measurement is not limited to LSV measurement (or CV measurement), and may be, for example, chronoamperometry (CA) measurement. Further, the electrochemical measurement may be performed with the test liquid stationary, or may be performed with the test liquid flowing. When performing LSV measurement (or CV measurement) while the test liquid is flowing, no current peak appears in the resulting voltammogram, but the concentration of the test substance can be determined by reading the current value at a predetermined applied voltage. Measurement is possible. Also in this modification, by performing the above-mentioned determination process and, if necessary, the above-mentioned pre-processing before implementing the concentration measurement process (electrochemical measurement), the sensor 10 can be electrically It becomes possible to carry out chemical measurements. That is, this modification also provides the same effects as the above embodiments and modifications.

(Modification 7)
In the above-mentioned embodiments and modifications, an example has been described in which all of the electrodes mounted on the sensor 10, that is, all of the working electrode 15, the counter electrode 16, and the reference electrode 17 are BDD electrodes. Not limited. At least the working electrode 15 may be a BDD electrode, and the counter electrode 16 and the reference electrode 17 may be electrodes formed using any known material in addition to the BDD electrode. The counter electrode 16 can be, for example, an electrode made of metal such as Pt, Au, Cu, Pd, Ni, Ag, or a carbon electrode. The reference electrode 17 is, for example, an electrode made of a metal such as Pt, Au, Cu, Pd, Ni, or Ag, a carbon electrode, a silver/silver chloride (Ag/AgCl) electrode, a standard hydrogen electrode, a reversible hydrogen electrode, or a palladium electrode. - Hydrogen electrodes, saturated calomel electrodes, etc. can also be used. When the counter electrode 16 or the reference electrode 17 is an electrode made of the metal described above, the counter electrode 16 or the reference electrode 17 may be formed integrally with the wiring 14 by a subtractive method, a semi-additive method, or the like. Also in this modification, by performing the above-mentioned determination process and pre-processing as necessary before implementing the concentration measurement process, the sensor 10 in a highly sensitive state is used to perform the concentration measurement process (electrochemical measurement).

(Modification 8)
In the above-mentioned embodiments and modified examples, an example in which the BDD electrode is a vertical electrode, that is, an example in which conduction is established from the back surface of the BDD electrode has been described, but the present invention is not limited to this. A conductive wiring may be connected to the surface of the electrode film 21 using solder, silver paste, or the like to establish conduction from the surface of the BDD electrode. Further, when establishing conduction from the surface of the BDD electrode, a ceramic substrate or a substrate made of a high-resistance material may be used instead of the conductive substrate 22 as the substrate supporting the electrode film 21.

Note that when establishing continuity from the surface of the electrode film 21, it is necessary to cover the solder or silver paste with thermosetting resin or ultraviolet curable resin to prevent the solder or silver paste from coming into contact with the test liquid during LSV measurement. be. However, since the resin before curing is liquid (paste), the surface of the electrode film 21 that contributes to O ₃ detection (i.e., the surface that is not covered with thermosetting resin or ultraviolet curable resin) It is difficult to adjust the area of the surface of the part to a predetermined area. For this reason, errors tend to occur in the current peak values obtained by LSV measurement between the plurality of sensors 10. From the viewpoint of reducing variations in measurement accuracy among the plurality of sensors 10, it is preferable that the BDD electrode be configured as a vertical electrode that conducts from the back surface of the substrate 22 as described above.

<Other aspects>
Aspects and modifications of the present disclosure have been specifically described above. However, the present disclosure is not limited to the above-described embodiments and modifications, and various changes can be made without departing from the spirit thereof.

<Preferred embodiments of the present disclosure>
Preferred embodiments of the present disclosure will be additionally described below.

(Additional note 1)
According to one aspect of the present disclosure,
An electrochemical measurement method for measuring the concentration of a test substance in a test liquid, the method comprising:
Attaching an electrochemical sensor to the electrochemical measuring device, the method comprising at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material;
carrying out electrochemical measurement of the concentration of the test substance with the working electrode and the counter electrode in contact with the test liquid,
If at least one of the following (1) to (4) applies, at least the working electrode and the pair are added to the treatment liquid containing the test substance before the step of performing the electrochemical measurement. A step of applying a potential exceeding the oxidation-reduction potential of the test substance to the working electrode while the electrodes are in contact with each other, and performing pretreatment once or multiple times to cause an electrochemical reaction on the surface of the working electrode. An electrochemical measurement method is provided, further comprising:
(1) When performing the step of performing the electrochemical measurement for the first time after performing the step of attaching the electrochemical sensor to the electrochemical measurement device; (2) When the step of performing the electrochemical measurement is performed first; In the case where the step of performing the electrochemical measurement is repeatedly performed using the same electrochemical sensor without removing the sensor, a predetermined period of time has elapsed since the time when the step of performing the previous electrochemical measurement was performed. (However, this excludes cases where the step of performing the pretreatment is performed after the previous step of performing the electrochemical measurement.)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measuring device, the electrochemical (However, this excludes cases where the step of performing the electrochemical measurement is performed after the previous step of performing the pretreatment)
(4) In the case where the step of performing the electrochemical measurement using the same electrochemical sensor is repeated without removing the electrochemical sensor from the electrochemical measuring device, the previous electrochemical measurement is repeated. When performing electrochemical measurement of the concentration of a test substance different from the test substance measured in the process to be carried out.

(Additional note 2)
The measuring method according to Supplementary note 1, preferably,
As the electrochemical sensor, a two-electrode sensor in which the working electrode and the counter electrode are mounted, or a three-electrode sensor in which the working electrode, the counter electrode, and a reference electrode are mounted is used.

(Additional note 3)
The measuring method according to appendix 2, preferably,
All of the electrodes mounted on the electrochemical sensor (i.e., when the electrochemical sensor is a two-electrode sensor, the working electrode and the counter electrode; when the electrochemical sensor is a three-electrode sensor, the above-mentioned The working electrode, the counter electrode, and the reference electrode are diamond electrodes each having an electrode film made of boron-doped diamond polycrystal on its surface.

(Additional note 4)
The measuring method according to any one of Supplementary Notes 1 to 3, preferably,
The electrochemical measurement is one of linear sweep voltammetry, cyclic voltammetry, and chronoamperometry.

(Appendix 5)
The measuring method according to any one of Supplementary Notes 1 to 4, preferably,
The treatment liquid is the same as the test liquid.

(Appendix 6)
The measuring method according to any one of Supplementary Notes 1 to 5, preferably,
The treatment liquid used in the step of performing the pretreatment and the test liquid used in the step of performing the electrochemical measurement subsequent to the step of performing the pretreatment are the same test liquid. These are the liquids sampled separately from each.

(Appendix 7)
The measuring method according to any one of Supplementary Notes 1 to 6, preferably,
The test substance is dissolved ozone in water.

(Appendix 8)
The measuring method according to any one of Supplementary Notes 1 to 7, preferably,
The test substance is dissolved ozone in water,
As the working electrode, an electrode is used that has been subjected to a surface treatment such that a current peak corresponding to the ozone concentration in the test liquid is observed in a voltammogram obtained by linear sweep voltammetry measurement.

(Appendix 9)
The measuring method according to any one of Supplementary Notes 1 to 8, preferably,
The test substance is dissolved ozone in water,
In the step of performing the pretreatment, a potential exceeding the redox potential of ozone is applied to the working electrode while the working electrode and the counter electrode are in contact with the treatment liquid containing ozone at a concentration of 0.1 ppm or more. Apply.

(Appendix 10)
According to other aspects of the disclosure:
An electrochemical measuring device for measuring the concentration of a test substance in a test liquid,
At least, the electrochemical sensor is configured such that it can be attached to an electrochemical sensor including a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material,
Before causing an electrochemical reaction on the surface of the working electrode by applying a preset potential to the working electrode while at least the working electrode and the counter electrode are in contact with the treatment solution containing the analyte. A function to perform processing a preset number of times,
a function of performing electrochemical measurement of the concentration of the test substance while the working electrode and the counter electrode are in contact with the test liquid;
If at least one of the following (1) to (3) applies, a function to prompt the implementation of the pretreatment before performing the electrochemical measurement;
An electrochemical measuring device is provided having the following.
(1) When performing the electrochemical measurement for the first time after installing the electrochemical sensor in the electrochemical measurement device, (2) When performing the electrochemical measurement for the first time without removing the electrochemical sensor from the electrochemical measurement device, In the case where the electrochemical measurement is repeatedly performed using the electrochemical sensor, when the electrochemical measurement is performed after a predetermined time has elapsed from the time when the previous electrochemical measurement was performed (provided that , except when the pretreatment is performed after the previous electrochemical measurement)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measuring device, the electrochemical (Excluding cases where the electrochemical measurement is performed after the previous pretreatment)

(Appendix 11)
According to still other aspects of the present disclosure:
An electrochemical measuring device for measuring the concentration of a test substance in a test liquid,
At least, the electrochemical sensor is configured such that it can be attached to an electrochemical sensor including a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material,
comprising a display section that displays the concentration of the test substance,
A function of selecting a calibration curve based on input information from the measuring person when the measuring person inputs in advance instructions for the test substance to be measured;
A preset potential is applied to the working electrode while at least the working electrode and the counter electrode of the electrochemical sensor attached to the electrochemical measurement device are in contact with the treatment liquid containing the analyte. a function of performing a pretreatment a preset number of times to cause an electrochemical reaction on the surface of the working electrode;
a function of carrying out electrochemical measurement of a current value corresponding to the concentration of the test substance in a state in which at least the working electrode and the counter electrode are in contact with the test liquid;
a function of calculating the concentration of the test substance from the measured current value using the selected calibration curve;
a function of displaying the calculated concentration of the test substance on the display section;
If at least one of the following (1) to (4) applies, a function that prompts the implementation of the pretreatment before performing the electrochemical measurement;
An electrochemical measuring device is provided having the following.
(1) When performing the electrochemical measurement for the first time after installing the electrochemical sensor in the electrochemical measurement device, (2) When performing the electrochemical measurement for the first time without removing the electrochemical sensor from the electrochemical measurement device, In the case where the electrochemical measurement is repeatedly performed using the electrochemical sensor, when the electrochemical measurement is performed after a predetermined time has elapsed from the time when the previous electrochemical measurement was performed (provided that , except when the pretreatment is performed after the previous electrochemical measurement)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measurement device, the electrochemical (Excluding cases where the electrochemical measurement is performed after the previous pretreatment)
(4) In the case where the electrochemical measurement is repeatedly carried out using the same electrochemical sensor without removing the electrochemical sensor from the electrochemical measurement device, the electrochemical measurement that was measured in the previous electrochemical measurement When carrying out the electrochemical measurement of the concentration of another test substance different from the test substance.

(Appendix 12)
The measuring device according to appendix 10 or 11, preferably,
a function of recording the time when the electrochemical sensor was attached to the electrochemical measurement device, the time when the electrochemical measurement was performed, and the time when the pretreatment was performed;
(a) the time when the electrochemical sensor was attached to the electrochemical measurement device; (b) the time when the previous electrochemical measurement was performed; and (c) the time when the previous pretreatment was performed. A function to extract the latest time,
If the extracted time is (a), a function of issuing a warning to the measurer that the pre-processing is necessary;
If the extracted time is (b) or (c), and the time from the time (b) or (c) to the time of extraction exceeds a predetermined time, the preprocessing is necessary. function to issue a warning to the measurer,
The method further includes a function of not performing the electrochemical measurement until the pretreatment is performed a preset number of times after issuing the warning.

(Appendix 13)
The measuring device according to any one of appendices 10 to 12, preferably,
The electrochemical sensor is a two-electrode sensor in which the working electrode and the counter electrode are mounted, or a three-electrode sensor in which the working electrode, the counter electrode, and a reference electrode are mounted.

(Appendix 14)
The measuring device according to any one of Supplementary Notes 10 to 13, preferably,
The working electrode, the counter electrode, and the reference electrode are each a diamond electrode having an electrode film made of boron-doped diamond polycrystal on its surface.

(Appendix 15)
The measuring device according to any one of appendices 10 to 14, preferably,
The electrochemical measurement is one of linear sweep voltammetry, cyclic voltammetry, and chronoamperometry.

(Appendix 16)
The measuring device according to any one of Supplementary Notes 10 to 15, preferably,
The test substance is dissolved ozone in water.

(Appendix 17)
The measuring device according to any one of appendices 10 to 16, preferably,
Before carrying out the electrochemical measurement, a function of carrying out a current conduction test (for example, a function of measuring the resistivity between arbitrary electrodes by an AC two-electrode method);
A function that prompts maintenance or replacement of the sensor if the current conduction resistance between any electrodes measured by the current conduction test exceeds a predetermined value;
a function of performing the electrochemical measurement when the current carrying resistance is less than or equal to a predetermined value;
has.

(Appendix 18)
The measuring device according to any one of Supplementary Notes 11 to 17, preferably,
A screen prompting implementation of the pre-processing is displayed on the display unit.

(Appendix 19)
The measuring device according to appendix 17, preferably,
A screen prompting maintenance or replacement of the sensor is displayed on the display unit.

(Additional note 20)
The measuring device according to appendix 10, preferably,
further comprising a display section,
A screen prompting implementation of the pre-processing is displayed on the display unit.

(Additional note 21)
The measuring device according to any one of appendices 10 to 20, preferably,
It further includes an input section,
The preprocessing is performed in response to a command from the input section.

(Additional note 22)
The measuring device according to any one of appendices 10 to 21, preferably,
It further has a function of detecting attachment and detachment of the electrochemical sensor from the electrochemical measuring device.

(Additional note 23)
The measuring device according to any one of appendices 11 to 22, preferably,
Further equipped with a storage section,
The storage unit stores in advance the calibration curve, the conditions for performing the electrochemical measurement, and the conditions for performing the pretreatment, which correspond to various test substances.

(Additional note 24)
The measuring device according to any one of appendices 10 to 23, preferably,
The main body of the measuring device has water resistance.

(Additional note 25)
The measuring device according to appendix 17, preferably,
The concentration of the test substance in the test liquid sampled from the same test liquid is measured using the sensor before and after replacement, and the measurement results are compared to determine the correlation between the sensor sensitivities before and after replacement. Has a function.

(Additional note 26)
According to still other aspects of the present disclosure,
It has at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material, and is attached to an electrochemical measuring device for measuring the concentration of a test substance in a test liquid. a step of performing electrochemical measurement of the concentration of the test substance in a state where the working electrode and the counter electrode of the electrochemical sensor are in contact with the test liquid;
If at least one of the following (1) to (4) applies, at least the working electrode and the electrode are added to the treatment solution containing the test substance before the electrochemical measurement procedure. A procedure of applying a potential exceeding the redox potential of the test substance to the working electrode while the electrodes are in contact with each other, and performing pretreatment once or multiple times to cause an electrochemical reaction on the surface of the working electrode. and,
A program configured to cause a computer to execute the program or a computer-readable recording medium recording the program is provided.
(1) When the electrochemical sensor is attached to the electrochemical measurement device, when the procedure for performing the electrochemical measurement is first performed (2) When the electrochemical sensor is removed from the electrochemical measurement device In the case where the procedure for performing the electrochemical measurement is repeatedly performed using the same electrochemical sensor without any interruption, after a predetermined period of time has elapsed from the time when the procedure for performing the previous electrochemical measurement was performed. , when causing the procedure for performing the electrochemical measurement to be executed (however, excluding the case where the procedure for performing the pretreatment is executed after the previous procedure for performing the electrochemical measurement)
(3) In the case where the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measuring device, the electrochemical (However, this excludes cases where the procedure for performing the electrochemical measurement is executed after the previous procedure for performing the pretreatment)
(4) In the case where the procedure for performing the electrochemical measurement using the same electrochemical sensor is repeatedly performed without removing the electrochemical sensor from the electrochemical measurement device, the electrochemical measurement performed previously When performing electrochemical measurement of the concentration of another test substance different from the test substance measured by the procedure of

10 Electrochemical sensor 15 Working electrode 16 Counter electrode 21 Electrode film 100 Electrochemical measuring device

Claims (18)

An electrochemical measurement method for measuring the concentration of dissolved ozone in a test liquid,
Attaching an electrochemical sensor to the electrochemical measuring device, the method comprising at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material;
carrying out electrochemical measurement of the concentration of dissolved ozone with the working electrode and the counter electrode in contact with the test liquid,
If at least one of the following (1) to (4) applies, at least the above action is applied to the treatment liquid containing ozone at a concentration of 0.1 ppm or more before the step of performing the electrochemical measurement. With the electrode and the counter electrode in contact, a potential exceeding the redox potential of ozone is applied to the working electrode to cause an electrochemical reaction on the surface of the working electrode. Pretreatment is performed once or multiple times. An electrochemical measurement method further comprising a step.
(1) When performing the step of performing the electrochemical measurement for the first time after performing the step of attaching the electrochemical sensor to the electrochemical measurement device; (2) When the step of performing the electrochemical measurement is performed first; Where the step of performing the electrochemical measurement is repeated using the same electrochemical sensor without removing the sensor , and the pretreatment is performed after the step of performing the previous electrochemical measurement. When carrying out the step of carrying out the electrochemical measurement after a predetermined period of time has elapsed from the time when the previous step of carrying out the electrochemical measurement was carried out, in the case where the step of carrying out the electrochemical measurement has not been carried out.
( 3) When the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measurement device , and the electrochemical measurement is performed after the previous step of performing the pretreatment. When carrying out the step of carrying out the electrochemical measurement after a predetermined period of time has elapsed from the time when the last pretreatment was carried out, in the case where the step of carrying out the electrochemical measurement is not carried out.
( 4) When carrying out the step of electrochemically measuring the concentration of dissolved ozone using the same electrochemical sensor without removing the electrochemical sensor from the electrochemical measuring device, When performing electrochemical measurement of the concentration of a test substance different from ozone in chemical measurement The electrochemical sensor according to claim 1, wherein a two-electrode sensor in which the working electrode and the counter electrode are mounted, or a three-electrode sensor in which the working electrode, the counter electrode, and a reference electrode are mounted is used. Electrochemical measurement method. 3. The electrochemical measurement method according to claim 2, wherein all of the electrodes mounted on the electrochemical sensor are diamond electrodes having an electrode film made of boron-doped diamond polycrystal on the surface. The electrochemical measurement method according to any one of claims 1 to 3, wherein the electrochemical measurement is any one of linear sweep voltammetry, cyclic voltammetry, and chronoamperometry. The electrochemical measurement method according to any one of claims 1 to 3, wherein the treatment liquid is the same as the test liquid. The treatment liquid used in the step of performing the pretreatment and the test liquid used in the step of performing the electrochemical measurement subsequent to the step of performing the pretreatment are the same test liquid. The electrochemical measurement method according to any one of claims 1 to 3, wherein the liquids are sampled separately from each other. Claims 1 to 3, wherein the working electrode is an electrode that has been subjected to a surface treatment such that a current peak corresponding to the ozone concentration in the test liquid is observed in a voltammogram obtained by linear sweep voltammetry measurement. The electrochemical measurement method according to any one of the above. An electrochemical measuring device having a function of measuring the concentration of dissolved ozone in a test liquid,
At least, the electrochemical sensor is configured such that it can be attached to an electrochemical sensor including a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material,
At least the working electrode and the counter electrode of the electrochemical sensor attached to the electrochemical measurement device are set in advance on the working electrode in a state in which they are in contact with a treatment liquid containing ozone at a concentration of 0.1 ppm or more. a function of applying a preset potential to cause an electrochemical reaction on the surface of the working electrode a preset number of times;
a function of electrochemically measuring the concentration of dissolved ozone while the working electrode and the counter electrode are in contact with the test liquid;
If at least one of the following (1) to (3) applies, a function to prompt the implementation of the pretreatment before performing the electrochemical measurement;
An electrochemical measurement device having:
(1) When performing the electrochemical measurement for the first time after installing the electrochemical sensor in the electrochemical measurement device, (2) When performing the electrochemical measurement for the first time without removing the electrochemical sensor from the electrochemical measurement device, In the case where the electrochemical measurement is repeatedly performed using the electrochemical sensor and the pretreatment is not performed after the previous electrochemical measurement , the previous electrochemical measurement is performed repeatedly. When carrying out the electrochemical measurement after a predetermined period of time has elapsed from the time at which it was carried out.
( 3) When the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measurement device , and the electrochemical measurement is not performed after the previous pretreatment. , when performing the electrochemical measurement after a predetermined period of time has passed since the last time the pretreatment was performed. An electrochemical measuring device having a function of measuring the concentration of dissolved ozone in a test liquid,
At least, the electrochemical sensor is configured such that it can be attached to an electrochemical sensor including a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material,
comprising a display section that displays at least the measurement result of the concentration of dissolved ozone ,
A function that selects a calibration curve based on the input information from the measurer when the measurer inputs in advance an instruction that the measurement target is dissolved ozone ;
At least the working electrode and the counter electrode of the electrochemical sensor attached to the electrochemical measurement device are brought into contact with a treatment solution containing ozone at a concentration of 0.1 ppm or more , and a preset ozone A function of applying a redox potential of
A function of carrying out electrochemical measurement of a current value corresponding to the concentration of dissolved ozone in a state in which at least the working electrode and the counter electrode are in contact with the test liquid;
a function of calculating the concentration of the dissolved ozone from the measured current value using the selected calibration curve;
a function of displaying the calculated concentration of dissolved ozone on the display section;
If at least one of the following (1) to (4) applies, a function that prompts the implementation of the pretreatment before performing the electrochemical measurement;
An electrochemical measurement device having:
(1) When performing the electrochemical measurement for the first time after installing the electrochemical sensor in the electrochemical measurement device, (2) When performing the electrochemical measurement for the first time without removing the electrochemical sensor from the electrochemical measurement device, In the case where the electrochemical measurement is repeatedly performed using the electrochemical sensor and the pretreatment is not performed after the previous electrochemical measurement , the previous electrochemical measurement is performed repeatedly. When carrying out the electrochemical measurement after a predetermined period of time has elapsed from the time at which it was carried out.
( 3) When the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measurement device , and the electrochemical measurement is not performed after the previous pretreatment. , when performing the electrochemical measurement after a predetermined time has elapsed from the time when the last pretreatment was performed.
( 4) In the case where the electrochemical measurement of the concentration of dissolved ozone is carried out using the same electrochemical sensor without removing the electrochemical sensor from the electrochemical measuring device, the previous electrochemical When conducting electrochemical measurements of the concentration of a test substance different from ozone . a function of recording the time when the electrochemical sensor was attached to the electrochemical measurement device, the time when the electrochemical measurement was performed, and the time when the pretreatment was performed;
(a) the time when the electrochemical sensor was attached to the electrochemical measurement device; (b) the time when the previous electrochemical measurement was performed; and (c) the time when the previous pretreatment was performed. A function to extract the latest time,
If the extracted time is (a), a function of issuing a warning to the measurer that the pre-processing is necessary;
If the extracted time is (b) or (c), and the time from the time (b) or (c) to the time of extraction exceeds a predetermined time, the preprocessing is necessary. function to issue a warning to the measurer,
The electrochemical measurement device according to claim 8 or 9 , further comprising a function of not performing the electrochemical measurement until the pretreatment is performed a preset number of times after issuing the warning. The electrochemical sensor is a two-electrode sensor in which the working electrode and the counter electrode are mounted, or a three-electrode sensor in which the working electrode, the counter electrode, and a reference electrode are mounted. The electrochemical measuring device described. The electrochemical measurement device according to claim 8 or 9 , wherein the electrochemical measurement is one of linear sweep voltammetry, cyclic voltammetry, and chronoamperometry. A function of carrying out an energization test before carrying out the electrochemical measurement;
A function that prompts maintenance or replacement of the sensor if the current conduction resistance between any electrodes measured by the current conduction test exceeds a predetermined value;
a function of performing the electrochemical measurement when the current carrying resistance is less than or equal to a predetermined value;
The electrochemical measurement device according to claim 8 or 9 , comprising: The electrochemical measuring device according to claim 9 , wherein a screen prompting implementation of the pretreatment is displayed on the display unit. It further includes an input section,
The electrochemical measurement device according to claim 8 or 9 , wherein the pretreatment is performed in response to a command from the input section. The electrochemical measuring device according to claim 8 or 9 , further having a function of detecting attachment and detachment of the electrochemical sensor from the electrochemical measuring device. Further equipped with a storage section,
The storage unit stores in advance at least the calibration curve, the conditions for performing the electrochemical measurement, and the conditions for performing the pretreatment, according to the measurement of the concentration of dissolved ozone . Item 9. Electrochemical measurement device according to item 9 . It has at least a working electrode having an electrode film made of a material containing diamond and a counter electrode made of an arbitrary material, and is attached to an electrochemical measuring device for measuring the concentration of dissolved ozone in a test liquid. a step of performing electrochemical measurement of the concentration of dissolved ozone with the working electrode and the counter electrode of the electrochemical sensor in contact with the test liquid;
If at least one of the following (1) to (4) applies, at least the above action is applied to the treatment liquid containing ozone at a concentration of 0.1 ppm or more before the step of performing the electrochemical measurement. With the electrode and the counter electrode in contact, a potential exceeding the redox potential of ozone is applied to the working electrode to cause an electrochemical reaction on the surface of the working electrode. Pretreatment is performed once or multiple times. steps and
A program that is configured to cause a computer to run.
(1) When the electrochemical sensor is attached to the electrochemical measurement device, when the procedure for performing the electrochemical measurement is first performed (2) When the electrochemical sensor is removed from the electrochemical measurement device A step in which the step of performing the electrochemical measurement using the same electrochemical sensor is repeated without any interruption, and the step of performing the pretreatment after performing the step of performing the previous electrochemical measurement. When the procedure for carrying out the electrochemical measurement is executed after a predetermined period of time has elapsed from the time when the procedure for carrying out the electrochemical measurement was previously executed, in the case where the procedure for carrying out the electrochemical measurement has not been carried out.
( 3) When the same electrochemical sensor is used without removing the electrochemical sensor from the electrochemical measurement device , and the electrochemical measurement is performed after performing the previous procedure for performing the pretreatment. When the procedure for performing the electrochemical measurement is performed after a predetermined period of time has elapsed since the last time the pretreatment was performed, in the case where the procedure for performing the electrochemical measurement is not performed.
( 4) In the case where the procedure for electrochemically measuring the concentration of dissolved ozone using the same electrochemical sensor without removing the electrochemical sensor from the electrochemical measuring device, When performing electrochemical measurement of the concentration of a test substance different from ozone in the procedure for performing electrochemical measurement.

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