WO2021039392A1 - Peracetic acid concentration meter - Google Patents

Peracetic acid concentration meter Download PDF

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Publication number
WO2021039392A1
WO2021039392A1 PCT/JP2020/030656 JP2020030656W WO2021039392A1 WO 2021039392 A1 WO2021039392 A1 WO 2021039392A1 JP 2020030656 W JP2020030656 W JP 2020030656W WO 2021039392 A1 WO2021039392 A1 WO 2021039392A1
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WO
WIPO (PCT)
Prior art keywords
peracetic acid
acid concentration
diaphragm
internal liquid
concentration meter
Prior art date
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PCT/JP2020/030656
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French (fr)
Japanese (ja)
Inventor
佳彦 川口
智子 甲斐
Original Assignee
株式会社堀場アドバンスドテクノ
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Application filed by 株式会社堀場アドバンスドテクノ filed Critical 株式会社堀場アドバンスドテクノ
Priority to JP2021542714A priority Critical patent/JP7489991B2/en
Publication of WO2021039392A1 publication Critical patent/WO2021039392A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems

Definitions

  • the present invention relates to a peracetic acid densitometer that measures the concentration of peracetic acid contained in a sample solution.
  • the peracetic acid concentration meter for example, there is a diaphragm type as described in Patent Document 1.
  • a diaphragm-type peracetic acid densitometer is provided with a diaphragm that selectively permeates peracetic acid, and the current change that occurs when the peracetic acid that has permeated the diaphragm undergoes a redox reaction on the surface of the working electrode. Is being measured.
  • the diaphragm that permeates peracetic acid also permeates hydrogen peroxide at the same time.
  • hydrogen peroxide permeates the diaphragm together with peracetic acid
  • hydrogen peroxide also reacts on the surface of the working electrode in the same manner as peracetic acid, so that there is a problem that an error occurs in the measurement of peracetic acid concentration.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a peracetic acid concentration meter capable of accurately measuring a peracetic acid concentration while suppressing an error due to hydrogen peroxide as small as possible. To do.
  • the peracetic acid concentration meter according to the present invention is a peracetic acid concentration meter of a diaphragm type for measuring the peracetic acid concentration of a sample solution, and the peracetic acid permeating the peracetic acid and the peracetic acid permeating the peracetic acid are dissolved. It is characterized by comprising an internal solution, an action electrode and a counter electrode immersed in the internal solution, and a catalyst for decomposing hydrogen peroxide in the internal solution.
  • the peracetic acid concentration meter configured in this way, since the catalyst for decomposing hydrogen peroxide in the internal liquid is provided, even if hydrogen peroxide permeates the diaphragm together with peracetic acid, it is contained in the internal liquid.
  • the concentration of hydrogen peroxide in the above can be suppressed sufficiently low. Therefore, the error caused by hydrogen peroxide contained in the internal liquid can be suppressed as small as possible, and the peracetic acid concentration can be measured more accurately than before.
  • the catalyst may be catalase.
  • the organic substance adheres to the surface of the diaphragm, or microorganisms propagate on the adhered organic substance to form a film, which adversely affects the measurement of peracetic acid concentration. May be given.
  • the cleaning of the diaphragm itself may be carried out because there is a risk of contamination of the sample solution by physical cleaning of a brush or the like or chemical contamination of the sample solution by chemical cleaning. It can be difficult.
  • a conductive mesh layer may be further provided on the surface of the diaphragm on the side in contact with the sample solution.
  • a predetermined voltage is applied to the conductive mesh layer, the organic matter adhering to the surface of the diaphragm can be decomposed and the growth of microorganisms can be suppressed.
  • the accuracy of peracetic acid concentration measurement can be further improved by decomposing and removing the peracetic acid remaining in the internal liquid.
  • a method of bringing the diaphragm into contact with zero water substantially free of peracetic acid for a predetermined time can be mentioned between the measurements.
  • the diaphragm while the diaphragm is in contact with zero water, peracetic acid does not enter the internal liquid, and the peracetic acid remaining in the internal liquid continues to be decomposed on the surface of the working electrode. .. Therefore, the peracetic acid concentration in the internal liquid can be reduced by providing a time for the diaphragm to be in contact with zero water. As a result, the measurement error due to the peracetic acid remaining in the internal liquid can be suppressed to a small value.
  • a light source for irradiating the peracetic acid concentration meter with ultraviolet rays In order to further improve the accuracy of the peracetic acid concentration measurement, it is preferable to provide a light source for irradiating the peracetic acid concentration meter with ultraviolet rays.
  • Ultraviolet rays decompose peroxides such as hydrogen peroxide to generate hydroxyl radicals. Hydroxyl radicals strongly decompose microorganisms and organic substances. Therefore, if a light source that irradiates the peracetic acid concentration meter with ultraviolet rays is provided, microorganisms and organic substances in the internal solution and the sample solution can be decomposed. As a result, for example, contamination of the working electrode surface and the diaphragm surface due to the adhesion of microorganisms and organic substances can be suppressed, and the measurement accuracy can be further improved.
  • the peracetic acid concentration measurement is provided with a peracetic acid concentration meter as described above and a flow path through which the sample solution flows, and the peracetic acid concentration of the sample solution flowing in the flow path is continuously measured using the peracetic acid concentration meter. It may be used as a device. In this case, a bypass flow path through which zero water flows may be provided separately from the main flow path through which the sample solution flows, and these may be switched at predetermined time intervals.
  • the error in the peracetic acid concentration measurement can be suppressed to a small value, and the peracetic acid concentration can be measured more accurately than before.
  • the schematic diagram of the peracetic acid concentration meter in one Embodiment of this invention. Schematic cross-sectional view of a peracetic acid densitometer according to an embodiment of the present invention. An enlarged cross-sectional view of an enlarged portion A of FIG. 3 in one embodiment of the present invention. An enlarged cross-sectional view of a portion A of FIG. 3 in another embodiment of the present invention.
  • the peracetic acid concentration meter in this embodiment is for immersing the peracetic acid concentration meter in a sample solution and measuring the peracetic acid concentration in the sample solution. Then, as shown in FIGS. 1 and 2, this peracetic acid concentration meter includes a container 1a for accommodating the internal liquid and a lid portion 1b for sealing the container 1a.
  • the container 1a has a hollow cylindrical shape with one end surface open and the other end surface closed, and when the lid portion 1b is attached so as to close the open end surface, the internal liquid 13 is accommodated therein. Space is formed. Further, a screw thread (not shown) for attaching the lid portion 1b is formed on the inner wall near the opening end.
  • a diaphragm 11 is provided on a part of the other end surface to allow a specific substance contained in the sample solution to permeate and penetrate into the container 1a.
  • the diaphragm 11 permeates peracetic acid, hydrogen peroxide, dissolved oxygen, residual chlorine, etc. in the sample solution, and is made of a material containing, for example, silicon, fluororesin, or polyethylene.
  • fluororesin for example, Teflon (registered trademark) or the like can be used.
  • film thickness of the diaphragm 11 for example, one having a thickness of 10 ⁇ m to 200 ⁇ m can be used.
  • the lid portion 1b seals the container 1a, and a holding member 16 for holding the working electrode 4 and the counter electrode 5 is provided so as to project from the substantially central portion on the container 1a side.
  • the holding member 16 is housed in a space formed between the container 1a and the lid 1b with the lid 1b attached to the container 1a. Further, on the opposite side of the container 1a side, a connector portion 6 to which a cable for connecting an external device is attached is provided.
  • the holding member 16 is made of an insulating material, and as shown in FIG. 3, surrounds the working pole 4 to hold the working pole 4, and winds and holds the counter electrode 5 around it. It is a thing. Further, the holding member 16 is provided with a spiral groove for attaching the lid portion 1b to the container 1a, and by fitting the lid portion 1b with a screw thread (not shown) provided on the container 1a side, the lid portion 1b can be fitted. It can be attached to the container 1a. Further, the holding member 16 is provided with an air hole 7 for discharging gas to the outside. A filter for separating gas and liquid is provided at one end of the opening of the air hole 7.
  • the working electrode 4 is made of a conductive material such as gold or platinum, and in the present embodiment, as shown in FIGS. 2 and 3, it has a rod shape, and one end thereof is shown in FIG. As described above, the holding member 16 is arranged so as to slightly protrude from the tip surface 10. Further, the surface of the working electrode 4 is provided with minute irregularities (not shown).
  • the counter electrode 5 is made of a conductive material such as platinum or silver-silver chloride (Ag / AgCl), and in the present embodiment, it is configured to have a linear shape.
  • the working electrode 4 and the counter electrode 5 are connected via a conducting wire 8, and a voltage is applied via the conducting wire 8 from an external power supply means (not shown). Further, the lead wire 8 is provided with an ammeter 9 for detecting the current flowing through the lead wire 8. The lead wire 8 and the ammeter 9 may be provided outside the lid portion 1b.
  • the internal liquid 13 is housed in the space formed between the lid portion 1b and the container 1a in a state where the lid portion 1b is attached to the container 1a.
  • the internal liquid 13 uses a buffer solution having a buffering action against the hydrogen ion concentration, and does not contain a substance that reacts with peracetic acid.
  • the internal liquid 13 is composed of only a buffer solution.
  • the buffer solution is not particularly limited as long as it is a buffer solution, and an acidic buffer solution, a neutral buffer solution, an alkaline buffer solution and the like can be used, but more preferably an acidic buffer solution and a neutral buffer solution are used. it can.
  • a phosphate buffer solution, an acetate buffer solution, a tris, a boric acid buffer solution, a citrate buffer solution and the like can be used.
  • An interlayer film 12 having a wettability with respect to the internal liquid 13 is laminated on the diaphragm 11 arranged inside the container 1a.
  • the interlayer film 12 is arranged so as to be sandwiched between the diaphragm 11 and the working electrode 4 with the container 1a attached to the lid portion 1b, and the working electrode 4 comes into contact with the diaphragm 11 via the interlayer film 12.
  • the wettability means that there is an affinity between the intermediate film 12 and the internal liquid 13, the internal liquid 13 stays in the intermediate film 12, wets the intermediate film 12, and the internal liquid is on the surface of the intermediate film 12. It is shown that it has a property of forming a liquid layer according to 13.
  • the film thickness of the interlayer film 12 one having a film thickness of 1 ⁇ m to 200 ⁇ m can be used.
  • a material having an elastic modulus larger than the elastic modulus of the diaphragm 11 can be used, for example, a material composed of a polymer or the like, particularly polyimide, polytetrafluoroethylene (PTFE).
  • PTFE polytetrafluoroethylene
  • a mixed resin in which polyethylene and polyimide are mixed, polyimide, cellulose and the like can be used.
  • the interlayer film 12 is composed of a porous film in which innumerable pores 12a having a pore size of 0.05 ⁇ m to 100 ⁇ m, which are sufficiently smaller than the size of bubbles (500 ⁇ m or more) such as oxygen, are provided.
  • a protective film 17 is laminated on the diaphragm 11 arranged on the outside of the container 1a, avoiding the region where the diaphragm 11 contacts the interlayer film 12.
  • the material constituting the protective film 17 is not particularly limited, and for example, polypropylene, PFA, PET and the like can be used. It is desirable that the protective film 17 has a relatively high hardness.
  • the peracetic acid concentration meter includes a catalyst for decomposing the peracetic acid in the internal liquid.
  • catalase which is an enzyme that decomposes hydrogen peroxide
  • the concentration of catalase in the internal liquid may be in the range of 0.01 U / mg or more and 50 U / mg or less in terms of activity value, and is preferably 0.1 U / mg or more and 5 U / mg or less.
  • 1U is a unit representing the amount of catalase that decomposes 1 micromol of hydrogen peroxide per minute at 25 ° C. Since catalase in the internal liquid is an enzyme, it is possible that the catalytic activity may decrease depending on the usage environment and the like. In such a case, the internal fluid may be replaced with a new one, or the internal fluid may be replenished with new catalase.
  • the operation of the peracetic acid concentration meter 1 of the present invention having the above-described configuration will be described below.
  • the working electrode 4 comes into contact with the diaphragm 11 via the interlayer film 12, as shown in FIG. Specifically, since the working pole 4 is arranged so as to protrude from the tip surface 10, the working pole 4 comes into press contact with the diaphragm 11 via the interlayer film 12.
  • the internal liquid 13 is sealed between the container 1a and the lid portion 1b. As shown in FIG. 4, the enclosed internal liquid 13 penetrates into a minute gap between the diaphragm 11 and the intermediate film 12 and a minute gap between the intermediate film 12 and the working electrode 4.
  • the interlayer film 12 has a wettability with respect to the internal liquid 13
  • a liquid layer of the internal liquid 13 is formed on the surface of the interlayer film 12.
  • the intermediate film 12 is a porous film
  • the internal liquid 13 invades the inside of the intermediate film 12 from the pores 12a provided in the intermediate film 12. Therefore, the working electrode 4 contacts the interlayer film 12 via this liquid layer, and the intermediate film 12 also contacts the diaphragm 11 via the liquid layer.
  • the liquid layer described above is a very thin layer, it acts.
  • the pole 4 can be considered to be in contact with the diaphragm 11 substantially via the interlayer membrane 12.
  • the peracetic acid contained in the sample solution permeates the diaphragm 11, and the peracetic acid permeating the diaphragm 11 is formed between the container 1a and the lid portion 1b. It dissolves in the internal solution 13 contained in the space. Then, when a voltage is applied between the working electrode 4 and the counter electrode 5 from a power supply means (not shown) via the lead wire 8, peracetic acid undergoes a redox reaction on the surface of the working electrode 4 and on the surface of the counter electrode 5. A redox reaction occurs. Since a current flows through the lead wire 8 by these reactions, peracetic acid can be detected by measuring this current value with an ammeter 9.
  • the connector portion 6 of the peracetic acid concentration meter 1 is connected to an external device via a cable or the like, an output signal indicating the current value measured by the ammeter 9 is transmitted to the external device, and the external device transmits the output signal.
  • the concentration of peracetic acid can also be calculated.
  • the internal liquid 13 contains a catalyst that decomposes hydrogen peroxide, even if hydrogen peroxide permeates through the diaphragm 11 together with peracetic acid and dissolves in the internal liquid 13, the hydrogen peroxide in the internal liquid 13 is dissolved. It can be disassembled and reduced. As a result, the measurement error due to the reaction of hydrogen peroxide on the surface of the working electrode 4 can be reduced, and the peracetic acid concentration can be measured accurately.
  • catalase which is an enzyme, is used as the catalyst, only hydrogen peroxide contained in the internal liquid can be more selectively decomposed as compared with the case where other catalysts are used. ..
  • the peracetic acid contained in the sample solution is used. Since it does not react with the buffer solution, the concentration of peracetic acid in the sample solution does not decrease, and the disinfectant / sterilizing action of the sample solution can be maintained. Further, as described above, catalase contained as a catalyst in the internal solution selectively decomposes only hydrogen peroxide, so that even if the internal solution leaks to the sample solution side, the peracetic acid in the sample solution remains. The concentration does not decrease.
  • the buffer solution does not have persistence like iodine and bromine and catalase contained as a catalyst is not toxic, it is assumed that the internal solution 13 leaks into the sample solution used in the medical field and the food field. However, the effect on the living body can be prevented. In addition, since the buffer solution does not generate a toxic gas like bromine, the psychological burden on the operator can be reduced.
  • acetic acid in the sample solution is changed to acetic acid on the surface of the working electrode 4 by the above reaction, acetic acid may increase in the internal liquid 13 as the reaction proceeds, and the internal liquid 13 may shift to acidic.
  • the internal solution 13 of the present embodiment is composed of a buffer solution, it is possible to prevent the internal solution 13 from shifting to acidity.
  • the interlayer film 12 has a wettability with respect to the internal liquid 13, and a liquid layer formed by the internal liquid 13 is formed on the surface of the intermediate membrane 12, so that the internal liquid is formed on the surface of the working electrode 4 from this liquid layer. A specific substance dissolved in 13 can be supplied.
  • the distance between the diaphragm 11 and the working electrode 4 is increased to improve the responsiveness of the sensor, and the reaction on the surface of the working pole 4 is prevented from being hindered to prevent the sensitivity of the sensor from deteriorating. be able to.
  • the surface of the working electrode 4 is provided with minute irregularities, and the specific surface area in contact with the internal liquid 13 is increased due to these minute irregularities, so that the responsiveness of the reaction on the surface of the working electrode 4 can be improved. It can be improved further.
  • the internal liquid 13 in which the specific substance is dissolved passes through the pores 12a provided in the interlayer film 12 and is supplied to the surface of the working electrode 4, until the specific substance reaches the surface of the working electrode 4.
  • the distance can be further shortened, and the responsiveness on the surface of the working electrode 4 can be further improved.
  • the internal liquid 13 can be supplied to the surface of the working electrode 4 through the pores 12a, a specific substance can be detected stably.
  • the pore diameter of the pores 12a of the porous membrane is 0.05 ⁇ m to 100 ⁇ m, even if bubbles are generated in the sensor, the bubbles are sufficiently larger than the pores 12a and are in the pores 12a. Does not remain in. Therefore, the internal liquid 13 can be supplied to the surface of the working electrode 4 through the pores 12a without being hindered by the bubbles, so that deterioration of the sensitivity of the sensor can be prevented.
  • the elastic modulus (bulk modulus) of the interlayer film 12 is larger than the elastic modulus of the diaphragm 11, it is less likely to be deformed than the diaphragm 11, and the interlayer film 12 itself. However, it is possible to surely prevent the contact with the surface of the working pole 4 and improve the responsiveness at the working pole 4.
  • the distance between the working pole 4 and the diaphragm 11 can be further shortened, and the responsiveness on the surface of the working pole 4 is further improved. can do.
  • the holding member 16 is provided with the air hole 7, the internal pressure applied when the lid portion 1b is attached to the container 1a can be released from the air hole 7, and as described above, the inside of the sensor Even when bubbles (gas) are generated, the bubbles can be released from the air holes 7 to prevent the sensor from malfunctioning.
  • the protective film 17 since the protective film 17 is provided on the surface of the diaphragm 11 in contact with the sample solution so as to exclude the region where the diaphragm 11 contacts the interlayer film 12, the protective film 17 prevents the diaphragm 11 from being damaged. It is possible to prevent the internal liquid 13 from leaking to the sample solution side. Since the protective film 17 has a relatively high hardness, damage to the diaphragm 11 can be prevented more reliably. Further, it is possible to prevent impurities and the like in the sample solution from entering the internal liquid 13 through the diaphragm 11, and the detection accuracy can be improved.
  • the responsiveness of the working electrode 4 can be further improved by using the interlayer film 12 made of a polymer or the like, particularly polycarbonate.
  • the catalyst is not limited to the above-mentioned catalase, and may be any catalyst that promotes the decomposition of hydrogen peroxide and does not decompose peracetic acid.
  • the catalyst may be a noble metal such as platinum, platinum alloy, or titanium.
  • the precious metal described above may be present in the internal liquid. Therefore, the shape of these noble metals and the method of attaching them to the peracetic acid concentration meter 1 are not particularly limited, and for example, these noble metals formed into a rod shape or a plate shape may be immersed in the internal liquid.
  • the internal solution 13 becomes contaminated by the growth of microorganisms, and the reaction of peracetic acid on the surface of the working electrode 4 is inhibited or measured. There is a risk that the result will be inaccurate.
  • irradiation with ultraviolet rays can be mentioned.
  • the light source L1 is arranged inside a casing that houses an internal liquid such as a container 1a or a lid 1b so that the internal liquid is irradiated with ultraviolet rays, the ultraviolet rays from the light source L1 are directly inside.
  • the liquid can be irradiated.
  • Ultraviolet rays decompose hydrogen peroxide in the internal liquid to generate hydroxyl radicals, and these hydroxyl radicals can suppress the growth of microorganisms in the internal liquid. Hydroxyl radicals can also decompose organic substances that cause contamination of the working electrode.
  • Examples of the light source L1 include an ultraviolet LED and the like. For example, as shown in FIG. 8, if a wireless power supply type LED or the like is used, the light source L1 can be arranged inside the casing with a simple configuration without worrying about wiring or the like.
  • a preservative for example, sodium citrate, potassium citrate, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, sodium nitrite, sodium nitrite and the like may be used, and silver, copper and zinc.
  • Metal ions such as, natural components extracted from plants and the like can be mentioned.
  • a casing for containing the internal liquid such as the container 1a and the lid 1b.
  • a material containing an antibacterial component may be used.
  • the antibacterial component include, but are not limited to, metals such as silver, copper, and zinc, and natural antibacterial components extracted from plants.
  • the peracetic acid permeation is inhibited by the adhesion of stains such as organic substances derived from the sample solution to the surface of the diaphragm 11 in contact with the sample solution, and the propagation of microorganisms to form a film.
  • the conductive mesh layer 18 may be laminated on the surface of the diaphragm 11 on the side in contact with the sample solution. Examples of the conductive mesh layer 18 include a mesh-shaped metal sheet having an opening degree that does not hinder peracetic acid permeation through the diaphragm.
  • the material of the conductive mesh layer 18 may be any material having conductivity, and is not particularly limited, but it is preferable to use a material such as silver or SUS. If silver, SUS, or the like is used as the material of the conductive mesh layer 18, hydrogen peroxide can be efficiently decomposed to generate hydroxyl radicals, and these hydroxyl radicals allow the growth of microorganisms on the diaphragm surface and organic substances. This is because adhesion can be suppressed.
  • irradiation of the diaphragm 11 with ultraviolet rays can be mentioned as a method of suppressing stains on the surface of the diaphragm 11 in contact with the sample solution and the growth of microorganisms.
  • the light source L2 for irradiating the diaphragm with ultraviolet rays may be the same as the light source L1 for irradiating the internal liquid with ultraviolet rays, or the surface of the diaphragm 11 on the side in contact with the sample solution is irradiated with ultraviolet rays from the outside.
  • the light source L2 may be provided separately.
  • the light source L2 may be attached to the casing described above, or may be independently provided outside the peracetic acid densitometer, for example, as shown in FIG.
  • the above-mentioned peracetic acid concentration meter 1 may be used in a batch-type measurement method such as immersing in a sample solution stored in a sample container such as a beaker to measure the peracetic acid concentration, or the peracetic acid concentration meter 1 may be used.
  • a sample may be supplied to the arranged flow path and used by incorporating it into the peracetic acid concentration measuring device 100 for continuously or intermittently measuring the peracetic acid concentration.
  • the peracetic acid concentration measuring device 100 for continuously or intermittently measuring the peracetic acid concentration for example, as shown in FIG. 6, the peracetic acid concentration meter 1 as described above and the peracetic acid concentration meter 1 are used.
  • a sample supply stream that separates a sample solution to be measured from a measurement cell 19 housed inside and a production line (not shown) that uses peracetic acid in the measurement cell 19, and supplies the sample solution to the measurement cell 19.
  • a path 20 and a sample lead-out flow path 21 for leading out a sample solution from the measurement cell 19 can be mentioned.
  • the peracetic acid that has passed through the diaphragm 11 and dissolved in the internal liquid at the time of measurement reacts on the surface of the working electrode 4 and is gradually decomposed, but is decomposed in the internal liquid 13.
  • Peracetic acid that has not been used may remain. If the measurement is continuously continued with the peracetic acid remaining in the internal liquid 13, there is a problem that the sensitivity of the sensor changes and that it takes time for the measurement current to stabilize. As a result, the peracetic acid concentration may not be measured accurately.
  • the peracetic acid concentration measuring device 100 supplies the zero water supply flow path 22 that further supplies a liquid containing no peracetic acid (hereinafter, also referred to as zero water) to the measuring cell 19, and zero water in the measuring cell 19.
  • a supply switching mechanism 23 that is switchably connected to the supply flow path 22 or the sample supply flow path 20 may be further provided.
  • the flow path connected to the measurement cell 19 is switched from the sample supply flow path 20 to the zero water supply flow path 22.
  • Zero water may be supplied to the diaphragm 11 of the peracetic acid concentration meter 1 in the measurement cell for a predetermined time.
  • the switching mechanism 23 switches between a supply switching valve 23V such as a three-way valve and a supply switching valve 23V for switchably connecting the sample supply flow path 20 or the zero water supply flow path 22 and the measurement cell 19. It is provided with a supply switching control unit that outputs a command signal such as timing.
  • the information processing circuit included in the peracetic acid concentration measuring device 100 fulfills the function of the supply switching control unit, for example.
  • the information processing circuit includes, for example, a digital circuit including a CPU, a memory, a communication circuit, etc. (not shown) and an analog circuit including an amplifier, an AD converter, and the like. Then, this one exerts a function as the supply switching control unit by cooperating with the CPU and its peripheral circuits according to a program stored in the memory in advance.
  • This information processing circuit may be provided in the above-mentioned external device that calculates the peracetic acid concentration based on the output signal from the ammeter 9.
  • the zero water may be a liquid that does not substantially contain peracetic acid (peracetic acid concentration is 100 ppm or less), and is preferably a liquid that does not contain peracetic acid at all, such as pure water or tap water.
  • the timing of supplying zero water and the time of supplying zero water can be appropriately changed depending on the purpose of measurement, etc., but it is preferable to continuously supply zero water for 5 minutes or more, and to supply zero water for 15 minutes or more. It is more preferable to supply.
  • Zero water can also be supplied by not supplying the sample solution to the measurement cell, discharging the sample solution in the measurement cell, and making the diaphragm of the peracetic acid concentration meter non-contact with the sample solution. You can get the same effect as. In this case, in order to replace the inside of the measurement cell for removing the sample solution adhering to the diaphragm with a gas containing no peracetic acid, a gas containing no peracetic acid may be supplied from the zero water supply channel. Good.
  • the peracetic acid enters the internal liquid 13 through the diaphragm 11 while the zero water is being supplied. Since it does not come, if the peracetic acid remaining in the internal liquid 13 is decomposed by the reaction on the surface of the working electrode 4 in this state, the concentration of the peracetic acid remaining in the internal liquid 13 can be reduced. At this time, if there is a catalyst that decomposes hydrogen peroxide in the internal liquid 13 as described above, the hydrogen peroxide generated by the decomposition of peracetic acid can be quickly decomposed, so that more peracetic acid can be decomposed. The decomposition efficiency of hydrogen peroxide can be improved.
  • the sample lead-out flow path 21 of the peracetic acid concentration measuring device 100 described above may be connected to a production line or the like for reuse of the sample solution after measurement.
  • a discharge flow path 24 and a discharge switching mechanism 25 branching from the sample lead-out flow path 21 may be further provided. ..
  • the discharge switching mechanism 25 includes, for example, a discharge switching valve 25V such as a three-way valve and a discharge switching control unit that controls the discharge switching valve 25V.
  • the information processing circuit described above fulfills the function of the discharge switching control unit, for example.
  • the discharge flow path It is not necessary to provide 24 and the discharge switching mechanism 25.
  • the sample supply flow path 20 and the zero water supply flow path 22 are connected to the measurement cell 19 via the same pipe, but the sample supply flow path 20 and the zero water supply flow path 22 are completely mutually complete.
  • Independent tubes may be used, and the flow paths 20 and 22 may be connected to the measurement cell from different directions.
  • the discharge flow path 24 may not be branched from the sample lead-out flow path 21, but may be provided independently as a flow path completely separate from the sample lead-out flow path 21.
  • the tip portion of the container 1a described above may cover the diaphragm 11 as a protective member so as to avoid the region where the diaphragm 11 contacts the interlayer film 12. ..
  • the internal solution is a buffer solution that does not react with peracetic acid, but the internal solution may be a diaphragm-type peracetic acid concentration meter containing iodine ions and bromide ions.
  • the peracetic acid concentration meter has the same shape and has a peracetic acid concentration meter having a catalyst in the internal liquid (Example 1) and a peracetic acid concentration meter having no catalyst in the internal liquid (Comparative Example 1). ) And the peracetic acid concentration was measured, and the measurement error of each was investigated.
  • Example 1 a peracetic acid densitometer containing catalase in the internal liquid, which was described in detail in the above embodiment, was used.
  • a phosphate buffer solution (pH 7.0) in which KCl was dissolved so as to be 1 mol / L was used as the internal solution, and catalase was added so as to be 0.2 U / mg.
  • a sample solution containing peracetic acid but not hydrogen peroxide and a sample solution containing peracetic acid and hydrogen peroxide were prepared.
  • a sample solution containing peracetic acid and hydrogen peroxide a sample solution in which the hydrogen peroxide concentration was variously changed in the range of 0.0% to 3.5% was prepared.
  • the peracetic acid concentration of each of these sample solutions was measured using the above-mentioned peracetic acid concentration meter.
  • the peracetic acid concentration of the same sample solution as that measured by the peracetic acid concentration meter was measured in parallel by the titration method.
  • the difference between the concentration indicated value measured by the peracetic acid densitometer and the concentration indicated value measured by the titration method for accurately measuring the peracetic acid concentration by neutralization titration was defined as the measurement error.
  • the peracetic acid concentration was measured by the titration method using COM-1700 manufactured by Hiranuma Sangyo. The experiment was performed twice.
  • the results of the first time are shown in FIG. 7 (a), and the results of the second time are shown in FIG. 7 (b).
  • the vertical axis of the graph of FIG. 7 represents the measurement error
  • the horizontal axis represents the concentration of hydrogen peroxide contained in the sample solution.
  • Comparative Example 1 In Comparative Example 1, the same peracetic acid concentration meter as that used in Example 1 was used except that the internal solution did not contain catalase. The measurement error was calculated by the same procedure as in Example 1. The experiment was performed twice. The results of the first time are shown in FIG. 7 (a), and the results of the second time are shown in FIG. 7 (b).
  • the peracetic acid concentration of the sample solution containing hydrogen peroxide can be determined as compared with the case without a catalyst. It was found that the measurement error when measuring can be significantly reduced.
  • the error in the peracetic acid concentration measurement can be suppressed to a small value, and the peracetic acid concentration can be measured more accurately than before.

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Abstract

Provided is a peracetic acid concentration meter with which it is possible to precisely measure the concentration of peracetic acid while minimizing errors from hydrogen peroxide. This peracetic acid concentration meter is of a diaphragm type for measuring peracetic acid concentration in a sample solution, and is characterized by being equipped with: a diaphragm pervious to peracetic acid; an internal liquid in which the peracetic acid that has passed the diaphragm is dissolved; a working electrode and a counter electrode that are immersed in the internal liquid; and a catalyst that decomposes hydrogen peroxide present in the internal liquid.

Description

過酢酸濃度計Peracetic acid concentration meter
本発明は、試料溶液に含まれる過酢酸の濃度を測定する過酢酸濃度計に関する。 The present invention relates to a peracetic acid densitometer that measures the concentration of peracetic acid contained in a sample solution.
　過酢酸濃度計としては、例えば特許文献１に記載されたような隔膜式のものがある。
　このような隔膜式の過酢酸濃度計は、過酢酸を選択的に透過する隔膜を備えており、この隔膜を透過した過酢酸が作用極の表面で酸化還元反応をするときに発生する電流変化を測定している。 As the peracetic acid concentration meter, for example, there is a diaphragm type as described in Patent Document 1.
Such a diaphragm-type peracetic acid densitometer is provided with a diaphragm that selectively permeates peracetic acid, and the current change that occurs when the peracetic acid that has permeated the diaphragm undergoes a redox reaction on the surface of the working electrode. Is being measured.
　しかしながら、過酢酸を透過させる隔膜は、過酸化水素をも同時に透過させてしまう。過酸化水素が過酢酸とともに隔膜を透過してしまうと、作用極表面で過酢酸と同様に過酸化水素も反応してしまうので、過酢酸濃度測定に誤差が生じてしまうという問題がある。 However, the diaphragm that permeates peracetic acid also permeates hydrogen peroxide at the same time. When hydrogen peroxide permeates the diaphragm together with peracetic acid, hydrogen peroxide also reacts on the surface of the working electrode in the same manner as peracetic acid, so that there is a problem that an error occurs in the measurement of peracetic acid concentration.
特開２０１５－２３０１７３号公報JP-A-2015-230173
　本発明は、上記課題に鑑みてなされたものであり、過酸化水素による誤差をできるだけ小さく抑えて、精度よく過酢酸濃度を測定することができる過酢酸濃度計を提供することを主な目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide a peracetic acid concentration meter capable of accurately measuring a peracetic acid concentration while suppressing an error due to hydrogen peroxide as small as possible. To do.
　すなわち、本発明に係る過酢酸濃度計は、試料溶液の過酢酸濃度を測定する隔膜式の過酢酸濃度計であって、過酢酸を透過する隔膜と、前記隔膜を透過した過酢酸が溶解する内部液と、前記内部液に浸漬する作用極及び対極と、前記内部液中の過酸化水素を分解する触媒とを具備することを特徴とする。 That is, the peracetic acid concentration meter according to the present invention is a peracetic acid concentration meter of a diaphragm type for measuring the peracetic acid concentration of a sample solution, and the peracetic acid permeating the peracetic acid and the peracetic acid permeating the peracetic acid are dissolved. It is characterized by comprising an internal solution, an action electrode and a counter electrode immersed in the internal solution, and a catalyst for decomposing hydrogen peroxide in the internal solution.
このように構成した過酢酸濃度計によれば、前記内部液中の過酸化水素を分解する触媒を備えているので、過酢酸とともに過酸化水素が前記隔膜を透過したとしても、前記内部液中の過酸化水素の濃度を十分に低く抑えることができる。
そのため、前記内部液中に含まれる過酸化水素に起因する誤差をできるだけ小さく抑えて、従来よりも精度よく過酢酸濃度を測定することができる。 According to the peracetic acid concentration meter configured in this way, since the catalyst for decomposing hydrogen peroxide in the internal liquid is provided, even if hydrogen peroxide permeates the diaphragm together with peracetic acid, it is contained in the internal liquid. The concentration of hydrogen peroxide in the above can be suppressed sufficiently low.
Therefore, the error caused by hydrogen peroxide contained in the internal liquid can be suppressed as small as possible, and the peracetic acid concentration can be measured more accurately than before.
　本発明に係る過酢酸濃度計の具体的な態様としては、前記触媒がカタラーゼであるものを挙げることができる。 As a specific embodiment of the peracetic acid concentration meter according to the present invention, the catalyst may be catalase.
　過酢酸濃度測定においては、前記内部液や前記隔膜の汚れによっても誤差や電位のふらつきなどが生じることがある。
　内部液の汚れの原因の一つとして、内部液に侵入した微生物などの繁殖を挙げることができる。
　そこで、前記内部液又は該内部液を収容するケーシングが防腐剤又は抗菌成分を含有するものとすれば、内部液中での微生物の繁殖を抑えて前記内部液や前記隔膜の汚れを抑制することができ、過酢酸濃度の測定精度をより向上させることができる。 In the measurement of peracetic acid concentration, errors and potential fluctuations may occur due to the contamination of the internal liquid and the diaphragm.
One of the causes of contamination of the internal liquid is the propagation of microorganisms that have invaded the internal liquid.
Therefore, if the internal liquid or the casing containing the internal liquid contains a preservative or an antibacterial component, it is possible to suppress the growth of microorganisms in the internal liquid and suppress the contamination of the internal liquid and the diaphragm. The measurement accuracy of the peracetic acid concentration can be further improved.
　また、前記隔膜が有機物を含有する試料溶液に接触すると、前記隔膜の表面に有機物が付着したり、付着した有機物上に微生物が繁殖して被膜を形成したりして、過酢酸濃度測定に悪影響を与えることがある。 In addition, when the diaphragm comes into contact with a sample solution containing an organic substance, the organic substance adheres to the surface of the diaphragm, or microorganisms propagate on the adhered organic substance to form a film, which adversely affects the measurement of peracetic acid concentration. May be given.
　このような前記隔膜表面の汚れは、ブラシや水圧等によって洗浄することが考えられているが、洗浄のために別途洗浄装置を設けなければいけないことや洗浄によってセンサ寿命が短くなってしまうなどの問題がある。また、強固な汚れの場合には、ブラシや水圧による洗浄だけでは不十分であり、洗浄力の強い薬液が必要な合もある。 It is considered that such stains on the surface of the diaphragm are cleaned with a brush, water pressure, etc. However, a separate cleaning device must be provided for cleaning, and the cleaning shortens the sensor life. There's a problem. Further, in the case of strong stains, cleaning with a brush or water pressure is not enough, and a chemical solution having strong detergency may be required.
　特に、医薬食品類の生産プロセスにおける過酢酸濃度測定においては、ブラシなどの物理的洗浄による試料溶液の汚染や、薬液洗浄による試料溶液の化学的汚染の恐れがあることから前記隔膜の洗浄そのものが難しい場合もある。 In particular, in the measurement of peracetic acid concentration in the production process of pharmaceutical foods, the cleaning of the diaphragm itself may be carried out because there is a risk of contamination of the sample solution by physical cleaning of a brush or the like or chemical contamination of the sample solution by chemical cleaning. It can be difficult.
　そこで、前記隔膜の試料溶液と接触する側の表面上に導電性メッシュ層をさらに備えるようにしてもよい。
　この導電性メッシュ層に所定の電圧を印加すれば、前記隔膜表面に付着している有機物を分解し、微生物の繁殖を抑えることができる。
　このように前記隔膜表面の汚れを抑えることにより、前記隔膜表面の汚れによる過酢酸透過の阻害を抑えて、測定電流を安定させることができる。その結果、過酢酸濃度測定の精度をより向上させることができる。 Therefore, a conductive mesh layer may be further provided on the surface of the diaphragm on the side in contact with the sample solution.
When a predetermined voltage is applied to the conductive mesh layer, the organic matter adhering to the surface of the diaphragm can be decomposed and the growth of microorganisms can be suppressed.
By suppressing the fouling of the diaphragm surface in this way, it is possible to suppress the inhibition of peracetic acid permeation due to the fouling of the diaphragm surface and stabilize the measurement current. As a result, the accuracy of peracetic acid concentration measurement can be further improved.
　ところで、試料溶液の過酢酸濃度を連続して測定する場合には、前回の測定時に隔膜を透過した過酢酸が内部液中に残存していると、この残存している過酢酸によって測定誤差が生じてしまう。
　そこで、内部液中に残存している過酢酸を分解して取り除くことによって、過酢酸濃度測定の精度をさらに向上させることができる。 By the way, when the peracetic acid concentration of the sample solution is continuously measured, if the peracetic acid that has permeated the diaphragm during the previous measurement remains in the internal liquid, the measurement error will be caused by the remaining peracetic acid. It will occur.
Therefore, the accuracy of peracetic acid concentration measurement can be further improved by decomposing and removing the peracetic acid remaining in the internal liquid.
　具体的な実施態様としては、測定と測定との間に、過酢酸を実質的に含有しないゼロ水に隔膜を所定時間接触させる方法を挙げることができる。 As a specific embodiment, a method of bringing the diaphragm into contact with zero water substantially free of peracetic acid for a predetermined time can be mentioned between the measurements.
　このようにすれば、前記隔膜がゼロ水に接触している間は、過酢酸が内部液中に入って来ず、さらに内部液中に残存している過酢酸が作用極表面で分解され続ける。そのため、前記隔膜をゼロ水に接触させる時間を設けることで、内部液中の過酢酸濃度を下げることができる。
　その結果、内部液中に残存している過酢酸による測定誤差を小さく抑えることができる。 In this way, while the diaphragm is in contact with zero water, peracetic acid does not enter the internal liquid, and the peracetic acid remaining in the internal liquid continues to be decomposed on the surface of the working electrode. .. Therefore, the peracetic acid concentration in the internal liquid can be reduced by providing a time for the diaphragm to be in contact with zero water.
As a result, the measurement error due to the peracetic acid remaining in the internal liquid can be suppressed to a small value.
　過酢酸濃度測定の精度をより向上させるためには、過酢酸濃度計に対して紫外線を照射する光源を備えるとよい。
　紫外線は過酸化水素等の過酸化物を分解し、ヒドロキシラジカルを発生させる。ヒドロキシラジカルは、微生物や有機物を強力に分解する。そこで、過酢酸濃度計に対して紫外線を照射する光源を備えておけば、内部液や試料溶液中の微生物や有機物を分解することができる。その結果、例えば、微生物や有機物の付着による作用極表面や隔膜表面の汚染を抑えて、測定精度をより向上させることができる。 In order to further improve the accuracy of the peracetic acid concentration measurement, it is preferable to provide a light source for irradiating the peracetic acid concentration meter with ultraviolet rays.
Ultraviolet rays decompose peroxides such as hydrogen peroxide to generate hydroxyl radicals. Hydroxyl radicals strongly decompose microorganisms and organic substances. Therefore, if a light source that irradiates the peracetic acid concentration meter with ultraviolet rays is provided, microorganisms and organic substances in the internal solution and the sample solution can be decomposed. As a result, for example, contamination of the working electrode surface and the diaphragm surface due to the adhesion of microorganisms and organic substances can be suppressed, and the measurement accuracy can be further improved.
　前述したような過酢酸濃度計と試料溶液が流れる流路とを備え、流路内を流れる試料溶液の過酢酸濃度を、前記過酢酸濃度計を使用して連続的に測定する過酢酸濃度測定装置としても良い。
　この場合には、試料溶液が流れる主流路とは別に、ゼロ水が流れるバイパス流路を別途設けておいて、これらを所定時間ごとに切り替えるようにしても良い。 The peracetic acid concentration measurement is provided with a peracetic acid concentration meter as described above and a flow path through which the sample solution flows, and the peracetic acid concentration of the sample solution flowing in the flow path is continuously measured using the peracetic acid concentration meter. It may be used as a device.
In this case, a bypass flow path through which zero water flows may be provided separately from the main flow path through which the sample solution flows, and these may be switched at predetermined time intervals.
　本発明に係る過酢酸濃度計及び過酢酸濃度測定装置によれば、過酢酸濃度測定における誤差を小さく抑えて、従来よりも精度よく過酢酸濃度を測定することができる。 According to the peracetic acid concentration meter and the peracetic acid concentration measuring device according to the present invention, the error in the peracetic acid concentration measurement can be suppressed to a small value, and the peracetic acid concentration can be measured more accurately than before.
本発明の一実施形態における過酢酸濃度計の全体模式図。The whole schematic diagram of the peracetic acid concentration meter in one Embodiment of this invention. 本発明の一実施形態における過酢酸濃度計の概略図。The schematic diagram of the peracetic acid concentration meter in one Embodiment of this invention. 本発明の一実施形態における過酢酸濃度計の概略断面図。Schematic cross-sectional view of a peracetic acid densitometer according to an embodiment of the present invention. 本発明の一実施形態において図３のＡ部分を拡大した拡大断面図。An enlarged cross-sectional view of an enlarged portion A of FIG. 3 in one embodiment of the present invention. 本発明の他の実施形態における図３のＡ部分を拡大した拡大断面図。An enlarged cross-sectional view of a portion A of FIG. 3 in another embodiment of the present invention. 本発明の一実施形態における過酢酸濃度測定装置の全体模式図。The whole schematic diagram of the peracetic acid concentration measuring apparatus in one Embodiment of this invention. 本発明の一実施例における測定誤差を示すグラフ。The graph which shows the measurement error in one Example of this invention. 本発明の他の実施形態における過酢酸濃度計の概略断面図。Schematic cross-sectional view of a peracetic acid densitometer according to another embodiment of the present invention. 本発明の他の実施形態における過酢酸濃度計の概略断面図。Schematic cross-sectional view of a peracetic acid densitometer according to another embodiment of the present invention.
１００　　過酢酸濃度測定装置
１　　　　過酢酸濃度計
４　　　　作用極
５　　　　対極
１１　　　隔膜
１２　　　中間膜
１３　　　内部液 100 Peracetic acid concentration measuring device 1 Peracetic acid concentration meter 4 Working pole 5 Counter pole 11 Septum 12 Intermediate membrane 13 Internal liquid
　以下、本発明に係る過酢酸濃度計及び過酢酸濃度測定装置の一実施形態について図面を参照しながら説明する。 Hereinafter, an embodiment of the peracetic acid concentration meter and the peracetic acid concentration measuring device according to the present invention will be described with reference to the drawings.
　本実施形態における過酢酸濃度計は、この過酢酸濃度計を試料溶液に浸漬させて該試料溶液中の過酢酸濃度を測定するものである。そして、この過酢酸濃度計は、図１及び図２に示すように、内部液を収容するため容器１ａと、容器１ａを密閉するための蓋部１ｂとを備える。 The peracetic acid concentration meter in this embodiment is for immersing the peracetic acid concentration meter in a sample solution and measuring the peracetic acid concentration in the sample solution. Then, as shown in FIGS. 1 and 2, this peracetic acid concentration meter includes a container 1a for accommodating the internal liquid and a lid portion 1b for sealing the container 1a.
　容器１ａは、一端面が開口するとともに他端面が閉塞された中空の円筒形状をなすものであって、開口端を塞ぐように蓋部１ｂを取り付けると、その内部に内部液１３を収容するための空間が形成されるものである。また、その開口端付近の内壁には、蓋部１ｂを取り付けるための図示しないねじ山が形成される。 The container 1a has a hollow cylindrical shape with one end surface open and the other end surface closed, and when the lid portion 1b is attached so as to close the open end surface, the internal liquid 13 is accommodated therein. Space is formed. Further, a screw thread (not shown) for attaching the lid portion 1b is formed on the inner wall near the opening end.
　そして、他端面の一部には、試料溶液に含まれる特定物質を透過させて、容器１ａ内に侵入させる隔膜１１が設けられている。 A diaphragm 11 is provided on a part of the other end surface to allow a specific substance contained in the sample solution to permeate and penetrate into the container 1a.
　隔膜１１は、試料溶液中の過酢酸、過酸化水素、溶存酸素、残留塩素等を透過させるものであって、例えばシリコン、フッ素樹脂又はポリエチレンを含む材料から構成されるものである。なお、フッ素樹脂としては、例えばテフロン（登録商標）等を用いることができる。また、隔膜１１の膜厚としては、例えば１０μｍ～２００μｍのものを用いることができる。 The diaphragm 11 permeates peracetic acid, hydrogen peroxide, dissolved oxygen, residual chlorine, etc. in the sample solution, and is made of a material containing, for example, silicon, fluororesin, or polyethylene. As the fluororesin, for example, Teflon (registered trademark) or the like can be used. Further, as the film thickness of the diaphragm 11, for example, one having a thickness of 10 μm to 200 μm can be used.
　蓋部１ｂは、容器１ａを密閉するものであって、容器１ａ側の略中央部には、作用極４及び対極５を保持する保持部材１６が突出するように設けられている。この保持部材１６は、蓋部１ｂが容器１ａに取り付けられた状態で、容器１ａと蓋部１ｂとの間に形成される空間に収容されるものである。また、容器１ａ側の反対側には、外部機器を接続するためのケーブルが取り付けられるコネクタ部６が設けられている。 The lid portion 1b seals the container 1a, and a holding member 16 for holding the working electrode 4 and the counter electrode 5 is provided so as to project from the substantially central portion on the container 1a side. The holding member 16 is housed in a space formed between the container 1a and the lid 1b with the lid 1b attached to the container 1a. Further, on the opposite side of the container 1a side, a connector portion 6 to which a cable for connecting an external device is attached is provided.
　保持部材１６は、絶縁性材料から構成されるものであって、図３に示すように、作用極４の周囲を囲んで作用極４を保持するとともに、対極５を周囲に巻回して保持するものである。また、保持部材１６には、蓋部１ｂを容器１ａに取り付けるための螺旋状の溝が設けられており、容器１ａ側に設けられた図示しないねじ山と嵌合させることで、蓋部１ｂを容器１ａに取り付けることができる。さらに、保持部材１６には、外部へ気体を排出するための空気孔７が設けられている。なお、この空気孔７の開口一端には、気液を分離するフィルタが設けられている。 The holding member 16 is made of an insulating material, and as shown in FIG. 3, surrounds the working pole 4 to hold the working pole 4, and winds and holds the counter electrode 5 around it. It is a thing. Further, the holding member 16 is provided with a spiral groove for attaching the lid portion 1b to the container 1a, and by fitting the lid portion 1b with a screw thread (not shown) provided on the container 1a side, the lid portion 1b can be fitted. It can be attached to the container 1a. Further, the holding member 16 is provided with an air hole 7 for discharging gas to the outside. A filter for separating gas and liquid is provided at one end of the opening of the air hole 7.
　作用極４は、例えば金や白金等の導電性材料から構成されるものであって、本実施形態では、図２及び図３に示すように、棒形状をなし、その一端が図４に示すように、保持部材１６の先端面１０よりもわずかに突出するように配置されている。また、この作用極４の表面には図示しない微小な凹凸が設けられている。 The working electrode 4 is made of a conductive material such as gold or platinum, and in the present embodiment, as shown in FIGS. 2 and 3, it has a rod shape, and one end thereof is shown in FIG. As described above, the holding member 16 is arranged so as to slightly protrude from the tip surface 10. Further, the surface of the working electrode 4 is provided with minute irregularities (not shown).
　対極５は、例えば白金や銀－塩化銀（Ａｇ／ＡｇＣｌ）等の導電性材料から構成されるものであって、本実施形態では、線形状をなすように構成されている。 The counter electrode 5 is made of a conductive material such as platinum or silver-silver chloride (Ag / AgCl), and in the present embodiment, it is configured to have a linear shape.
　作用極４及び対極５は、図３に示すように、導線８を介して接続されており、該導線８を介して外部に設けられた図示しない電力供給手段から電圧が印加される。また、導線８には、導線８を流れる電流を検知する電流計９が設けられている。なお、導線８や電流計９は蓋部１ｂの外部に設けられたものであってもよい。 As shown in FIG. 3, the working electrode 4 and the counter electrode 5 are connected via a conducting wire 8, and a voltage is applied via the conducting wire 8 from an external power supply means (not shown). Further, the lead wire 8 is provided with an ammeter 9 for detecting the current flowing through the lead wire 8. The lead wire 8 and the ammeter 9 may be provided outside the lid portion 1b.
　そして、図１及び図３に示すように、蓋部１ｂを容器１ａに取り付けた状態で、蓋部１ｂと容器１ａとの間に形成される空間には内部液１３が収容される。
　この内部液１３は、水素イオン濃度に対して緩衝作用を有する緩衝液が用いられるものであって、過酢酸と反応する物質を含まないものである。本実施形態では、内部液１３が緩衝液のみで構成される。この緩衝液は、緩衝液であれば特に限定されず、酸性緩衝液、中性緩衝液、アルカリ性緩衝液等を用いることができるが、さらに好ましくは酸性緩衝液、中性緩衝液を用いることができる。本実施形態では、例えばリン酸緩衝液や酢酸緩衝液、トリス、ホウ酸緩衝液、クエン酸緩衝液等を用いることができる。 Then, as shown in FIGS. 1 and 3, the internal liquid 13 is housed in the space formed between the lid portion 1b and the container 1a in a state where the lid portion 1b is attached to the container 1a.
The internal liquid 13 uses a buffer solution having a buffering action against the hydrogen ion concentration, and does not contain a substance that reacts with peracetic acid. In the present embodiment, the internal liquid 13 is composed of only a buffer solution. The buffer solution is not particularly limited as long as it is a buffer solution, and an acidic buffer solution, a neutral buffer solution, an alkaline buffer solution and the like can be used, but more preferably an acidic buffer solution and a neutral buffer solution are used. it can. In this embodiment, for example, a phosphate buffer solution, an acetate buffer solution, a tris, a boric acid buffer solution, a citrate buffer solution and the like can be used.
　容器１ａの内側に配置する隔膜１１には、内部液１３に対してぬれ性を有する中間膜１２が積層されている。この中間膜１２は、容器１ａを蓋部１ｂに取り付けた状態で隔膜１１と作用極４との間に挟まれるように配置されて、作用極４をこの中間膜１２を介して隔膜１１に接触させるものである。ここで、ぬれ性とは、中間膜１２と内部液１３との間に親和性があり、中間膜１２に内部液１３が留まり、中間膜１２を濡れさせて、中間膜１２の表面に内部液１３による液層を形成する性質を有することを示す。この中間膜１２の膜厚としては、１μｍ～２００μｍのものを用いることができる。 An interlayer film 12 having a wettability with respect to the internal liquid 13 is laminated on the diaphragm 11 arranged inside the container 1a. The interlayer film 12 is arranged so as to be sandwiched between the diaphragm 11 and the working electrode 4 with the container 1a attached to the lid portion 1b, and the working electrode 4 comes into contact with the diaphragm 11 via the interlayer film 12. It is something to make. Here, the wettability means that there is an affinity between the intermediate film 12 and the internal liquid 13, the internal liquid 13 stays in the intermediate film 12, wets the intermediate film 12, and the internal liquid is on the surface of the intermediate film 12. It is shown that it has a property of forming a liquid layer according to 13. As the film thickness of the interlayer film 12, one having a film thickness of 1 μm to 200 μm can be used.
　また、中間膜１２に用いられる材料としては、隔膜１１の弾性率よりも大きい弾性率を有する材料を用いることができ、例えばポリマー等から構成されたもの、特にポリカーボネイト、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリエチレンとポリイミドを混合した混合樹脂、ポリイミド、セルロース等を用いることができる。
　そして、この中間膜１２は酸素等の気泡の大きさ（５００μｍ以上）よりも十分小さい孔径０．０５μｍ～１００μｍの細孔１２ａが無数に設けられ多孔質膜で構成されている。 Further, as the material used for the interlayer film 12, a material having an elastic modulus larger than the elastic modulus of the diaphragm 11 can be used, for example, a material composed of a polymer or the like, particularly polyimide, polytetrafluoroethylene (PTFE). , A mixed resin in which polyethylene and polyimide are mixed, polyimide, cellulose and the like can be used.
The interlayer film 12 is composed of a porous film in which innumerable pores 12a having a pore size of 0.05 μm to 100 μm, which are sufficiently smaller than the size of bubbles (500 μm or more) such as oxygen, are provided.
　また、容器１ａの外側に配置する隔膜１１には、隔膜１１が中間膜１２と接触する領域をさけて保護膜１７が積層されている。この保護膜１７を構成する材料としては特に限定されず、例えばポリプロピレン、ＰＦＡ、ＰＥＴ等を用いることができる。なお、この保護膜１７は、比較的硬度が高いことが望ましい。 Further, a protective film 17 is laminated on the diaphragm 11 arranged on the outside of the container 1a, avoiding the region where the diaphragm 11 contacts the interlayer film 12. The material constituting the protective film 17 is not particularly limited, and for example, polypropylene, PFA, PET and the like can be used. It is desirable that the protective film 17 has a relatively high hardness.
　しかして、本実施形態に係る過酢酸濃度計は、前記内部液中の過酢酸を分解する触媒を備えている。
　本実施形態では、過酸化水素を分解する酵素であるカタラーゼが前記内部液に添加されている。内部液中のカタラーゼの濃度は、活性値で０．０１U／mg以上５０U／mg以下の範囲であればよく、０．１U／mg以上５U／mg以下であることが好ましい。ここで、１Ｕは、２５℃で毎分１マイクロモルの過酸化水素を分解するカタラーゼの量を表す単位である。
　内部液中のカタラーゼは酵素であるので、使用環境等により触媒活性が低下することも考えられる。このような場合には、内部液を新しいものに取り替えたり、内部液中に新しいカタラーゼを補充したりすればよい。 Therefore, the peracetic acid concentration meter according to the present embodiment includes a catalyst for decomposing the peracetic acid in the internal liquid.
In the present embodiment, catalase, which is an enzyme that decomposes hydrogen peroxide, is added to the internal liquid. The concentration of catalase in the internal liquid may be in the range of 0.01 U / mg or more and 50 U / mg or less in terms of activity value, and is preferably 0.1 U / mg or more and 5 U / mg or less. Here, 1U is a unit representing the amount of catalase that decomposes 1 micromol of hydrogen peroxide per minute at 25 ° C.
Since catalase in the internal liquid is an enzyme, it is possible that the catalytic activity may decrease depending on the usage environment and the like. In such a case, the internal fluid may be replaced with a new one, or the internal fluid may be replenished with new catalase.
　上述した構成を備える本発明の過酢酸濃度計１の動作について以下に説明する。
　容器１ａに蓋部１ｂを取り付けると、作用極４は、図４に示すように、中間膜１２を介して隔膜１１に接触する。具体的には、作用極４は先端面１０から突出するように配置されているので、作用極４は、中間膜１２を介して隔膜１１と押圧接触する。 The operation of the peracetic acid concentration meter 1 of the present invention having the above-described configuration will be described below.
When the lid portion 1b is attached to the container 1a, the working electrode 4 comes into contact with the diaphragm 11 via the interlayer film 12, as shown in FIG. Specifically, since the working pole 4 is arranged so as to protrude from the tip surface 10, the working pole 4 comes into press contact with the diaphragm 11 via the interlayer film 12.
　また、容器１ａと蓋部１ｂとの間には、内部液１３が封入される。この封入された内部液１３は、図４に示すように、隔膜１１と中間膜１２との微小な隙間及び中間膜１２と作用極４との微小な隙間に侵入する。ここで、中間膜１２は、内部液１３に対してぬれ性を有するので、中間膜１２の表面には内部液１３の液層が形成される。また、中間膜１２は多孔質膜であるので、中間膜１２に設けられた細孔１２ａから中間膜１２の内部に内部液１３が侵入する。そのため、作用極４はこの液層を介して中間膜１２に接触するとともに、中間膜１２も液層を介して隔膜１１と接触するが、上述した液層は非常に薄い層であるので、作用極４は、実質的に中間膜１２を介して隔膜１１に接触しているものとみなすことができる。 Further, the internal liquid 13 is sealed between the container 1a and the lid portion 1b. As shown in FIG. 4, the enclosed internal liquid 13 penetrates into a minute gap between the diaphragm 11 and the intermediate film 12 and a minute gap between the intermediate film 12 and the working electrode 4. Here, since the interlayer film 12 has a wettability with respect to the internal liquid 13, a liquid layer of the internal liquid 13 is formed on the surface of the interlayer film 12. Further, since the intermediate film 12 is a porous film, the internal liquid 13 invades the inside of the intermediate film 12 from the pores 12a provided in the intermediate film 12. Therefore, the working electrode 4 contacts the interlayer film 12 via this liquid layer, and the intermediate film 12 also contacts the diaphragm 11 via the liquid layer. However, since the liquid layer described above is a very thin layer, it acts. The pole 4 can be considered to be in contact with the diaphragm 11 substantially via the interlayer membrane 12.
　そして、作用極４も内部液１３に浸漬されるとともに、対極５も内部液１３に浸漬されるので、内部液１３を介して作用極４と対極５とが電気的に接続される。 Then, since the working electrode 4 is also immersed in the internal liquid 13 and the counter electrode 5 is also immersed in the internal liquid 13, the working electrode 4 and the counter electrode 5 are electrically connected via the internal liquid 13.
　上述した隔膜式センサ１を、試料溶液に浸漬すると、試料溶液中に含まれる過酢酸が隔膜１１を透過し、隔膜１１を透過した過酢酸は、容器１ａと蓋部１ｂとの間に形成された空間に収容された内部液１３に溶解する。そして、作用極４と対極５との間に図示しない電力供給手段から導線８を介して電圧が印加されると、作用極４の表面で過酢酸が酸化還元反応するとともに、対極５の表面で酸化還元反応が生じる。これらの反応によって、導線８に電流が流れるので、この電流値を電流計９で測定すれば、過酢酸を検知することができる。 When the above-mentioned diaphragm type sensor 1 is immersed in the sample solution, the peracetic acid contained in the sample solution permeates the diaphragm 11, and the peracetic acid permeating the diaphragm 11 is formed between the container 1a and the lid portion 1b. It dissolves in the internal solution 13 contained in the space. Then, when a voltage is applied between the working electrode 4 and the counter electrode 5 from a power supply means (not shown) via the lead wire 8, peracetic acid undergoes a redox reaction on the surface of the working electrode 4 and on the surface of the counter electrode 5. A redox reaction occurs. Since a current flows through the lead wire 8 by these reactions, peracetic acid can be detected by measuring this current value with an ammeter 9.
　なお、例えば、過酢酸濃度計１のコネクタ部６をケーブル等を介して外部機器に接続して、外部機器に電流計９で測定された電流値を示す出力信号を送信して、外部機器で過酢酸の濃度を算出することもできる。 For example, the connector portion 6 of the peracetic acid concentration meter 1 is connected to an external device via a cable or the like, an output signal indicating the current value measured by the ammeter 9 is transmitted to the external device, and the external device transmits the output signal. The concentration of peracetic acid can also be calculated.
　上述したように構成した過酢酸濃度計１によれば、以下のような効果を奏することができる。 According to the peracetic acid concentration meter 1 configured as described above, the following effects can be obtained.
　前記内部液１３が過酸化水素を分解する触媒を含有しているので、過酸化水素が過酢酸とともに隔膜１１を透過して内部液１３に溶解したとしても、内部液１３中の過酸化水素を分解して減らすことができる。
　その結果、過酸化水素が作用極４の表面で反応することによる測定誤差を減らして、過酢酸濃度を精度よく測定することができる。
　本実施形態では、前記触媒として酵素であるカタラーゼを使用しているので、他の触媒を使用する場合に比べて、内部液中に含まれる過酸化水素だけをより選択的に分解することができる。 Since the internal liquid 13 contains a catalyst that decomposes hydrogen peroxide, even if hydrogen peroxide permeates through the diaphragm 11 together with peracetic acid and dissolves in the internal liquid 13, the hydrogen peroxide in the internal liquid 13 is dissolved. It can be disassembled and reduced.
As a result, the measurement error due to the reaction of hydrogen peroxide on the surface of the working electrode 4 can be reduced, and the peracetic acid concentration can be measured accurately.
In the present embodiment, since catalase, which is an enzyme, is used as the catalyst, only hydrogen peroxide contained in the internal liquid can be more selectively decomposed as compared with the case where other catalysts are used. ..
　内部液１３に、水素イオン濃度に対して緩衝作用を有する緩衝液が用いられるので、たとえ過酢酸濃度を測定中に内部液１３が試料溶液側に漏出したとしても、試料溶液に含まれる過酢酸と緩衝液とは反応しないので、試料溶液中の過酢酸の濃度が低下することはなく、試料溶液の消毒・滅菌作用を保つことができる。
　また、内部液中に触媒として含まれているカタラーゼは、前述したように、過酸化水素だけを選択的に分解するので、内部液が試料溶液側に漏出したとしても試料溶液中の過酢酸の濃度が低下することはない。
　また、緩衝液にヨウ素や臭素のような残留性はなく、触媒として含有されているカタラーゼにも毒性がないので、ので、内部液１３が医療分野や食品分野で用いられる試料溶液に漏出したとしても、生体への影響を防ぐことができる。　加えて、緩衝液は臭素のように有毒なガスが発生するものではないので、作業者の心理的な負担を軽減することができる。 Since a buffer solution having a buffering action against the hydrogen ion concentration is used as the internal solution 13, even if the internal solution 13 leaks to the sample solution side while measuring the peracetic acid concentration, the peracetic acid contained in the sample solution is used. Since it does not react with the buffer solution, the concentration of peracetic acid in the sample solution does not decrease, and the disinfectant / sterilizing action of the sample solution can be maintained.
Further, as described above, catalase contained as a catalyst in the internal solution selectively decomposes only hydrogen peroxide, so that even if the internal solution leaks to the sample solution side, the peracetic acid in the sample solution remains. The concentration does not decrease.
Further, since the buffer solution does not have persistence like iodine and bromine and catalase contained as a catalyst is not toxic, it is assumed that the internal solution 13 leaks into the sample solution used in the medical field and the food field. However, the effect on the living body can be prevented. In addition, since the buffer solution does not generate a toxic gas like bromine, the psychological burden on the operator can be reduced.
　また、試料溶液中の過酢酸は、上述した反応によって作用極４の表面で酢酸に変化するので、反応が進むにつれて内部液１３中に酢酸が増加して、内部液１３が酸性に移行するおそれがあるが、本実施形態の内部液１３は緩衝液で構成されるので、内部液１３が酸性に移行することを防ぐことができる。 Further, since peracetic acid in the sample solution is changed to acetic acid on the surface of the working electrode 4 by the above reaction, acetic acid may increase in the internal liquid 13 as the reaction proceeds, and the internal liquid 13 may shift to acidic. However, since the internal solution 13 of the present embodiment is composed of a buffer solution, it is possible to prevent the internal solution 13 from shifting to acidity.
　作用極４が中間膜１２を介して隔膜１１と接触しているので、作用極４と隔膜１１との距離を近づけながら、中間膜１２によって作用極４と隔膜１１とが隙間なく密着することを防ぐことができる。また、この中間膜１２は内部液１３に対してぬれ性を有し、中間膜１２の表面には内部液１３による液層が形成されるので、この液層から作用極４の表面に内部液１３に溶解した特定物質を供給することができる。そのため、隔膜１１と作用極４との距離を近づけてセンサの応答性を向上しながら、作用極４の表面での反応が阻害されることを防止して、センサの感度が悪化することを防ぐことができる。 Since the working pole 4 is in contact with the diaphragm 11 via the interlayer film 12, the working pole 4 and the diaphragm 11 are brought into close contact with each other by the interlayer film 12 while keeping the distance between the working pole 4 and the diaphragm 11 close. Can be prevented. Further, the interlayer film 12 has a wettability with respect to the internal liquid 13, and a liquid layer formed by the internal liquid 13 is formed on the surface of the intermediate membrane 12, so that the internal liquid is formed on the surface of the working electrode 4 from this liquid layer. A specific substance dissolved in 13 can be supplied. Therefore, the distance between the diaphragm 11 and the working electrode 4 is increased to improve the responsiveness of the sensor, and the reaction on the surface of the working pole 4 is prevented from being hindered to prevent the sensitivity of the sensor from deteriorating. be able to.
　また、本実施形態では作用極４の表面に微小な凹凸が設けられており、この微小な凹凸によって内部液１３と接触する比表面積が大きくなるので、作用極４表面での反応の応答性をより向上させることができる。 Further, in the present embodiment, the surface of the working electrode 4 is provided with minute irregularities, and the specific surface area in contact with the internal liquid 13 is increased due to these minute irregularities, so that the responsiveness of the reaction on the surface of the working electrode 4 can be improved. It can be improved further.
　さらに、特定物質が溶解した内部液１３が、中間膜１２に設けられた細孔１２ａを通過して作用極４の表面に供給されるので、特定物質が作用極４の表面に到達するまでの距離をさらに縮めることができ、作用極４の表面での応答性をより向上させることができる。また、細孔１２ａを通じて内部液１３を作用極４の表面に供給することができるので、安定的に特定物質を検知することができる。 Further, since the internal liquid 13 in which the specific substance is dissolved passes through the pores 12a provided in the interlayer film 12 and is supplied to the surface of the working electrode 4, until the specific substance reaches the surface of the working electrode 4. The distance can be further shortened, and the responsiveness on the surface of the working electrode 4 can be further improved. Further, since the internal liquid 13 can be supplied to the surface of the working electrode 4 through the pores 12a, a specific substance can be detected stably.
　また、多孔質膜の細孔１２ａの孔径が、０．０５μｍ～１００μｍであるので、センサ内に気泡が生じた場合であっても、この気泡は細孔１２ａよりも十分大きく、細孔１２ａ内に残存することがない。そのため、気泡によって阻害されることなく、作用極４の表面に細孔１２ａを通じて内部液１３を供給することができるので、センサの感度の悪化を防止することができる。 Further, since the pore diameter of the pores 12a of the porous membrane is 0.05 μm to 100 μm, even if bubbles are generated in the sensor, the bubbles are sufficiently larger than the pores 12a and are in the pores 12a. Does not remain in. Therefore, the internal liquid 13 can be supplied to the surface of the working electrode 4 through the pores 12a without being hindered by the bubbles, so that deterioration of the sensitivity of the sensor can be prevented.
　また、本実施形態における隔膜式センサ１では、中間膜１２の弾性率（体積弾性率）が隔膜１１の弾性率よりも大きいものであるので、隔膜１１に比べて変形し難く、中間膜１２自体が、作用極４の表面に密着することを確実に防いで、作用極４での応答性を向上することができる。 Further, in the diaphragm type sensor 1 of the present embodiment, since the elastic modulus (bulk modulus) of the interlayer film 12 is larger than the elastic modulus of the diaphragm 11, it is less likely to be deformed than the diaphragm 11, and the interlayer film 12 itself. However, it is possible to surely prevent the contact with the surface of the working pole 4 and improve the responsiveness at the working pole 4.
　さらに、作用極４が、中間膜１２を介して隔膜１１に押圧接触しているので、作用極４と隔膜１１との距離をより縮めることができ、作用極４表面での応答性をより向上することができる。 Further, since the working pole 4 is in pressure contact with the diaphragm 11 via the interlayer film 12, the distance between the working pole 4 and the diaphragm 11 can be further shortened, and the responsiveness on the surface of the working pole 4 is further improved. can do.
　加えて、保持部材１６に空気孔７が設けられているので、容器１ａに蓋部１ｂを取り付けた際にかかる内圧をこの空気孔７から逃がすことができるとともに、上述したように、センサ内に気泡（ガス）が生じた場合であっても、この気泡をこの空気孔７から逃がすことができ、センサの故障を防ぐことができる。 In addition, since the holding member 16 is provided with the air hole 7, the internal pressure applied when the lid portion 1b is attached to the container 1a can be released from the air hole 7, and as described above, the inside of the sensor Even when bubbles (gas) are generated, the bubbles can be released from the air holes 7 to prevent the sensor from malfunctioning.
　また、隔膜１１が中間膜１２と接触する領域を除くように、隔膜１１の試料溶液と接触する面に保護膜１７が設けられているので、保護膜１７によって隔膜１１が破損することを防ぎ、内部液１３が試料溶液側に漏出することを防ぐことができる。そして、保護膜１７が比較的硬度が大きいものを用いているので、隔膜１１の破損をより確実に防ぐことができる。また、試料溶液中の不純物等が隔膜１１を介して内部液１３内に侵入することを防ぐことができ、検知精度を高めることができる。 Further, since the protective film 17 is provided on the surface of the diaphragm 11 in contact with the sample solution so as to exclude the region where the diaphragm 11 contacts the interlayer film 12, the protective film 17 prevents the diaphragm 11 from being damaged. It is possible to prevent the internal liquid 13 from leaking to the sample solution side. Since the protective film 17 has a relatively high hardness, damage to the diaphragm 11 can be prevented more reliably. Further, it is possible to prevent impurities and the like in the sample solution from entering the internal liquid 13 through the diaphragm 11, and the detection accuracy can be improved.
　さらに、中間膜１２をポリマー等で構成する、特にポリカーボネイトを用いることで、作用極４の応答性をより向上させることができる。 Furthermore, the responsiveness of the working electrode 4 can be further improved by using the interlayer film 12 made of a polymer or the like, particularly polycarbonate.
　本発明は、その趣旨に反しない範囲で様々な変形が可能であり、前述の実施形態に限られない。
　例えば、前記触媒は前述したカタラーゼに限らず、過酸化水素の分解を促進するものであって、過酢酸を分解しないものであればよい。
　具体的には、前記触媒が、白金、白金合金、チタンなどの貴金属であっても良い。この場合には、前述した貴金属が内部液中に存在すればよい。
　そのため、これら貴金属の形状や過酢酸濃度計１への取り付け方は特に限定されず、例えば、棒状や板状に成形したこれら貴金属を内部液中に浸漬するなどしても良い。 The present invention can be modified in various ways without contrary to the gist thereof, and is not limited to the above-described embodiment.
For example, the catalyst is not limited to the above-mentioned catalase, and may be any catalyst that promotes the decomposition of hydrogen peroxide and does not decompose peracetic acid.
Specifically, the catalyst may be a noble metal such as platinum, platinum alloy, or titanium. In this case, the precious metal described above may be present in the internal liquid.
Therefore, the shape of these noble metals and the method of attaching them to the peracetic acid concentration meter 1 are not particularly limited, and for example, these noble metals formed into a rod shape or a plate shape may be immersed in the internal liquid.
　前述の実施形態のように、内部液１３に緩衝液を使用している場合には、内部液１３が微生物の繁殖によって汚れてしまい、作用極４表面における過酢酸の反応が阻害されたり、測定結果に誤差が生じてしまったりする恐れがある。
　内部液中での微生物の繁殖による測定結果への悪影響を抑える方法として、紫外線の照射を挙げることができる。例えば、容器１ａや蓋部１ｂなどの内部液を収容するケーシングの内部に前記光源Ｌ１を配置して、内部液に対して紫外線を照射するようにしておけば、光源Ｌ１からの紫外線を直接内部液に照射することができる。紫外線は、内部液中の過酸化水素を分解してヒドロキシラジカルを発生させるので、このヒドロキシラジカルによって内部液中での微生物の繁殖を抑えることができる。また、ヒドロキシラジカルによって、作用極の汚れの原因となる有機物を分解することもできる。
　前記光源Ｌ１としては、例えば、紫外LEDなどを挙げることができる。例えば、図８に示すように、ワイヤレス給電式のLED等を使用すれば、配線などを気にせず簡単な構成で前記ケーシングの内部に光源Ｌ１を配置することができる。 When a buffer solution is used as the internal solution 13 as in the above-described embodiment, the internal solution 13 becomes contaminated by the growth of microorganisms, and the reaction of peracetic acid on the surface of the working electrode 4 is inhibited or measured. There is a risk that the result will be inaccurate.
As a method of suppressing the adverse effect on the measurement result due to the propagation of microorganisms in the internal liquid, irradiation with ultraviolet rays can be mentioned. For example, if the light source L1 is arranged inside a casing that houses an internal liquid such as a container 1a or a lid 1b so that the internal liquid is irradiated with ultraviolet rays, the ultraviolet rays from the light source L1 are directly inside. The liquid can be irradiated. Ultraviolet rays decompose hydrogen peroxide in the internal liquid to generate hydroxyl radicals, and these hydroxyl radicals can suppress the growth of microorganisms in the internal liquid. Hydroxyl radicals can also decompose organic substances that cause contamination of the working electrode.
Examples of the light source L1 include an ultraviolet LED and the like. For example, as shown in FIG. 8, if a wireless power supply type LED or the like is used, the light source L1 can be arranged inside the casing with a simple configuration without worrying about wiring or the like.
　内部液中での微生物の繁殖による測定結果への悪影響を抑える他の方法として、例えば、内部液１３に防腐剤を添加することを挙げることができる。
　前記防腐剤としては、例えば、クエン酸ナトリウム、クエン酸カリウム、安息香酸、安息香酸ナトリウム、ソルビン酸、ソルビン酸カリウム、亜硫酸塩、亜硝酸ナトリウム等を使用してもよいし、銀、銅、亜鉛などの金属イオン、植物等から抽出された天然成分などを挙げることができる。 As another method of suppressing the adverse effect on the measurement result due to the propagation of microorganisms in the internal liquid, for example, addition of a preservative to the internal liquid 13 can be mentioned.
As the preservative, for example, sodium citrate, potassium citrate, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, sodium nitrite, sodium nitrite and the like may be used, and silver, copper and zinc. Metal ions such as, natural components extracted from plants and the like can be mentioned.
　内部液１３中の微生物の繁殖を抑えるには、内部液１３に紫外線を照射したり、防腐剤を添加したりする以外にも、例えば、容器１ａや蓋部１ｂ等の内部液を収容するケーシングの素材に抗菌成分を含有するものを使用してもよい。この抗菌成分としては、例えば、銀、銅、亜鉛などの金属や、植物から抽出された天然の抗菌成分等を挙げることができるが、これらに限られない。 In order to suppress the growth of microorganisms in the internal liquid 13, in addition to irradiating the internal liquid 13 with ultraviolet rays and adding a preservative, for example, a casing for containing the internal liquid such as the container 1a and the lid 1b. A material containing an antibacterial component may be used. Examples of the antibacterial component include, but are not limited to, metals such as silver, copper, and zinc, and natural antibacterial components extracted from plants.
　さらに、隔膜１１の試料溶液と接触する表面に、試料溶液由来の有機物などの汚れが付着したり、微生物が繁殖して被膜を形成したりすることによって、過酢酸の透過が阻害されることを防ぐために、例えば、図５に示すように、隔膜１１の試料溶液と接触する側の表面に導電性メッシュ層１８を積層しても良い。
　この導電性メッシュ層１８としては、過酢酸の隔膜透過を阻害しない程度の開口度を有するメッシュ状の金属シート等を挙げることができる。
　この導電性メッシュ層１８に電圧を印加すれば、隔膜１１の試料溶液側の表面に付着している有機物などの汚れを分解することができる。例えば、導電性メッシュ層１８への電圧印加を一定時間毎に行うようにすれば、隔膜１１の汚れをより効果的に抑制することができる。
　導電性メッシュ層１８の素材は導電性を有するものであればよく、特に限定されないが、銀やＳＵＳ等の素材を使用することが好ましい。導電性メッシュ層１８の素材として、銀やＳＵＳ等を使用すれば、過酸化水素を効率よく分解してヒドロキシラジカルを発生させることができ、このヒドロキシラジカルによって隔膜表面での微生物の繁殖や有機物の付着を抑えることができるからである。 Furthermore, the peracetic acid permeation is inhibited by the adhesion of stains such as organic substances derived from the sample solution to the surface of the diaphragm 11 in contact with the sample solution, and the propagation of microorganisms to form a film. In order to prevent this, for example, as shown in FIG. 5, the conductive mesh layer 18 may be laminated on the surface of the diaphragm 11 on the side in contact with the sample solution.
Examples of the conductive mesh layer 18 include a mesh-shaped metal sheet having an opening degree that does not hinder peracetic acid permeation through the diaphragm.
By applying a voltage to the conductive mesh layer 18, dirt such as organic substances adhering to the surface of the diaphragm 11 on the sample solution side can be decomposed. For example, if the voltage is applied to the conductive mesh layer 18 at regular intervals, the dirt on the diaphragm 11 can be suppressed more effectively.
The material of the conductive mesh layer 18 may be any material having conductivity, and is not particularly limited, but it is preferable to use a material such as silver or SUS. If silver, SUS, or the like is used as the material of the conductive mesh layer 18, hydrogen peroxide can be efficiently decomposed to generate hydroxyl radicals, and these hydroxyl radicals allow the growth of microorganisms on the diaphragm surface and organic substances. This is because adhesion can be suppressed.
　隔膜１１の試料溶液と接する表面の汚れや微生物の繁殖を抑制する方法としては、前述した以外にも、隔膜１１に紫外線を照射することを挙げることができる。
　前記隔膜に紫外線を照射する光源Ｌ２は、前述した内部液に紫外線を照射する場合の光源Ｌ１と同じものであっても良いし、隔膜１１の試料溶液に接する側の面に外側から紫外線を照射する光源Ｌ２を別途設けても良い。この光源Ｌ２は、前述したケーシングに取り付けられていても良いし、例えば、図９に示すように、前記過酢酸濃度計の外部に独立して設けられていても良い。 In addition to the above, irradiation of the diaphragm 11 with ultraviolet rays can be mentioned as a method of suppressing stains on the surface of the diaphragm 11 in contact with the sample solution and the growth of microorganisms.
The light source L2 for irradiating the diaphragm with ultraviolet rays may be the same as the light source L1 for irradiating the internal liquid with ultraviolet rays, or the surface of the diaphragm 11 on the side in contact with the sample solution is irradiated with ultraviolet rays from the outside. The light source L2 may be provided separately. The light source L2 may be attached to the casing described above, or may be independently provided outside the peracetic acid densitometer, for example, as shown in FIG.
　前述した過酢酸濃度計１は、ビーカーなどの試料容器に貯留した試料溶液に浸漬して過酢酸濃度を測定するようなバッチ式の測定方法に使用しても良いし、過酢酸濃度計１を配置した流路に試料を供給して過酢酸濃度を連続的又は断続的に測定する過酢酸濃度測定装置１００に組み込んで使用してもよい。
　過酢酸濃度を連続的又は断続的に測定する過酢酸濃度測定装置１００の例としては、例えば、図６に示すように、前述したような過酢酸濃度計１と、該過酢酸濃度計１を内部に収容する測定セル１９と、該測定セル１９に例えば、過酢酸を使用している図示しない生産ライン等から測定対象である試料溶液を分取して前記測定セル１９に供給する試料供給流路２０と、前記測定セル１９から試料溶液を導出する試料導出流路２１とを備えたものを挙げることができる。 The above-mentioned peracetic acid concentration meter 1 may be used in a batch-type measurement method such as immersing in a sample solution stored in a sample container such as a beaker to measure the peracetic acid concentration, or the peracetic acid concentration meter 1 may be used. A sample may be supplied to the arranged flow path and used by incorporating it into the peracetic acid concentration measuring device 100 for continuously or intermittently measuring the peracetic acid concentration.
As an example of the peracetic acid concentration measuring device 100 for continuously or intermittently measuring the peracetic acid concentration, for example, as shown in FIG. 6, the peracetic acid concentration meter 1 as described above and the peracetic acid concentration meter 1 are used. A sample supply stream that separates a sample solution to be measured from a measurement cell 19 housed inside and a production line (not shown) that uses peracetic acid in the measurement cell 19, and supplies the sample solution to the measurement cell 19. A path 20 and a sample lead-out flow path 21 for leading out a sample solution from the measurement cell 19 can be mentioned.
　このような過酢酸濃度測定装置１００の場合、測定時に隔膜１１を透過して内部液に溶解した過酢酸は作用極４の表面で反応して少しずつ分解されるが、内部液１３中に分解されないままの過酢酸が残留してしまうことがある。
　内部液１３中に過酢酸が残留したまま連続して測定を続けると、センサの感度が変化してしまうという問題や、測定電流が安定するまでに時間がかかってしまうという問題がある。その結果、過酢酸濃度が精度良く測定できない可能性がある。 In the case of such a peracetic acid concentration measuring device 100, the peracetic acid that has passed through the diaphragm 11 and dissolved in the internal liquid at the time of measurement reacts on the surface of the working electrode 4 and is gradually decomposed, but is decomposed in the internal liquid 13. Peracetic acid that has not been used may remain.
If the measurement is continuously continued with the peracetic acid remaining in the internal liquid 13, there is a problem that the sensitivity of the sensor changes and that it takes time for the measurement current to stabilize. As a result, the peracetic acid concentration may not be measured accurately.
　そのため、過酢酸濃度の測定精度をより向上するには、内部液中に残留している過酢酸を取り除くことが好ましい。
　そこで、前記過酢酸濃度測定装置１００が、さらに過酢酸を含有しない液体（以下、ゼロ水ともいう。）を前記測定セル１９に供給するゼロ水供給流路２２と、前記測定セル１９をゼロ水供給流路２２又は前記試料供給流路２０に切り替え可能に接続する供給切替機構２３とをさらに具備するようにしてもよい。 Therefore, in order to further improve the measurement accuracy of the peracetic acid concentration, it is preferable to remove the peracetic acid remaining in the internal liquid.
Therefore, the peracetic acid concentration measuring device 100 supplies the zero water supply flow path 22 that further supplies a liquid containing no peracetic acid (hereinafter, also referred to as zero water) to the measuring cell 19, and zero water in the measuring cell 19. A supply switching mechanism 23 that is switchably connected to the supply flow path 22 or the sample supply flow path 20 may be further provided.
　その上で、測定と測定との間に、例えば定期的にタイミングを設定して、前記測定セル１９に接続する流路を、前記試料供給流路２０から前記ゼロ水供給流路２２に切り替えて、前記測定セル内の過酢酸濃度計１の隔膜１１にゼロ水を所定時間の間供給するようにすればよい。
　前記切替機構２３は、例えば、試料供給流路２０又はゼロ水供給流路２２と測定セル１９とを切替可能に接続する、３方弁などの供給切替バルブ２３Ｖと、該供給切替バルブ２３Ｖに切替タイミングなどの指令信号を出力する供給切替制御部とを備えるものである。
　前記供給切替制御部は、例えば、前記過酢酸濃度測定装置１００が備える情報処理回路がその機能を果たすものである。該情報処理回路は、例えば図示しないＣＰＵ、メモリ、通信回路等からなるデジタル回路と、増幅器、ＡＤコンバータ等からなるアナログ回路とからなるものである。そしてこのものは、前記メモリに予め記憶させたプログラムにしたがってＣＰＵやその周辺回路が協動することにより前記供給切替制御部としての機能を発揮する。
　この情報処理回路は、電流計９からの出力信号に基づいて過酢酸濃度を算出する前述した外部機器に備えられているものであっても良い。
　前記ゼロ水は、実質的に過酢酸を含有しない液体（過酢酸濃度が１００ｐｐｍ以下）であればよく、例えば、純水や水道水などの過酢酸を全く含まない液体であることが好ましい。
　ゼロ水を供給するタイミングやゼロ水を供給する時間は、測定の目的等によって適宜変更することができるが、連続して５分以上ゼロ水を供給し続けることが好ましく、１５分以上ゼロ水を供給することがより好ましい。
　また、測定セルに試料溶液を供給しないようにして、測定セル中の試料溶液を排出し、過酢酸濃度計の隔膜を試料溶液と非接触の状態にすることによっても、ゼロ水を供給するのと同じ効果を得ることができる。
　この場合には、隔膜に付着した試料溶液を除去する測定セル内を過酢酸を含まない気体で置換するために、ゼロ水供給流路から、過酢酸を含まない気体を供給するようにしてもよい。 Then, for example, by periodically setting a timing between measurements, the flow path connected to the measurement cell 19 is switched from the sample supply flow path 20 to the zero water supply flow path 22. , Zero water may be supplied to the diaphragm 11 of the peracetic acid concentration meter 1 in the measurement cell for a predetermined time.
The switching mechanism 23 switches between a supply switching valve 23V such as a three-way valve and a supply switching valve 23V for switchably connecting the sample supply flow path 20 or the zero water supply flow path 22 and the measurement cell 19. It is provided with a supply switching control unit that outputs a command signal such as timing.
The information processing circuit included in the peracetic acid concentration measuring device 100 fulfills the function of the supply switching control unit, for example. The information processing circuit includes, for example, a digital circuit including a CPU, a memory, a communication circuit, etc. (not shown) and an analog circuit including an amplifier, an AD converter, and the like. Then, this one exerts a function as the supply switching control unit by cooperating with the CPU and its peripheral circuits according to a program stored in the memory in advance.
This information processing circuit may be provided in the above-mentioned external device that calculates the peracetic acid concentration based on the output signal from the ammeter 9.
The zero water may be a liquid that does not substantially contain peracetic acid (peracetic acid concentration is 100 ppm or less), and is preferably a liquid that does not contain peracetic acid at all, such as pure water or tap water.
The timing of supplying zero water and the time of supplying zero water can be appropriately changed depending on the purpose of measurement, etc., but it is preferable to continuously supply zero water for 5 minutes or more, and to supply zero water for 15 minutes or more. It is more preferable to supply.
Zero water can also be supplied by not supplying the sample solution to the measurement cell, discharging the sample solution in the measurement cell, and making the diaphragm of the peracetic acid concentration meter non-contact with the sample solution. You can get the same effect as.
In this case, in order to replace the inside of the measurement cell for removing the sample solution adhering to the diaphragm with a gas containing no peracetic acid, a gas containing no peracetic acid may be supplied from the zero water supply channel. Good.
　このように測定と測定との間に、過酢酸濃度計１にゼロ水を供給するようにすれば、ゼロ水を供給している間は隔膜１１を介して過酢酸が内部液１３に入って来ないので、この状態で内部液１３中に残留している過酢酸を作用極４表面での反応によって分解すれば、内部液１３中に残留する過酢酸の濃度を下げることができる。
　この時、前述したように内部液１３中の過酸化水素を分解する触媒が存在していれば、過酢酸が分解することによって発生する過酸化水素を素早く分解することができるので、より過酢酸の分解効率を向上させることができる。 If zero water is supplied to the peracetic acid concentration meter 1 between the measurements in this way, the peracetic acid enters the internal liquid 13 through the diaphragm 11 while the zero water is being supplied. Since it does not come, if the peracetic acid remaining in the internal liquid 13 is decomposed by the reaction on the surface of the working electrode 4 in this state, the concentration of the peracetic acid remaining in the internal liquid 13 can be reduced.
At this time, if there is a catalyst that decomposes hydrogen peroxide in the internal liquid 13 as described above, the hydrogen peroxide generated by the decomposition of peracetic acid can be quickly decomposed, so that more peracetic acid can be decomposed. The decomposition efficiency of hydrogen peroxide can be improved.
　前述した過酢酸濃度測定装置１００の試料導出流路２１が、測定後の試料溶液の再利用等のために生産ライン等に接続されていることがある。このような場合であって、ゼロ水が生産ライン等に混入することを防ぎたい場合には、前記試料導出流路２１から分岐する排出流路２４及び排出切替機構２５等をさらに設けてもよい。このようにしておけば、測定セル１９に供給されたゼロ水をこの排出流路２４から外部へ排出することができる。なお、前記排出切替機構２５は、例えば、３方弁などの排出切替バルブ２５Ｖと、該排出切替バルブ２５Ｖを制御する排出切替制御部とを備えるものである。該排出切替制御部は、例えば、前述した情報処理回路がその機能を果たす。
　一方で、ゼロ水が試料導出流路２１から生産ライン等に混入しても問題がない場合や、前記試料導出流路２１がそもそも生産ライン等に接続されていない場合などには、排出流路２４及び排出切替機構２５を設ける必要はない。 The sample lead-out flow path 21 of the peracetic acid concentration measuring device 100 described above may be connected to a production line or the like for reuse of the sample solution after measurement. In such a case, if it is desired to prevent zero water from being mixed into the production line or the like, a discharge flow path 24 and a discharge switching mechanism 25 branching from the sample lead-out flow path 21 may be further provided. .. By doing so, the zero water supplied to the measurement cell 19 can be discharged to the outside from the discharge flow path 24. The discharge switching mechanism 25 includes, for example, a discharge switching valve 25V such as a three-way valve and a discharge switching control unit that controls the discharge switching valve 25V. The information processing circuit described above fulfills the function of the discharge switching control unit, for example.
On the other hand, if there is no problem even if zero water is mixed into the production line or the like from the sample lead-out flow path 21, or if the sample lead-out flow path 21 is not connected to the production line or the like in the first place, the discharge flow path It is not necessary to provide 24 and the discharge switching mechanism 25.
　図６では、試料供給流路２０とゼロ水供給流路２２とが同一の管を経て測定セル１９に接続されているが、試料供給流路２０と、ゼロ水供給流路２２とは互いに完全に独立した管を使用しているものであっても良く、これら流路２０、２２が測定セルに対して互いに互いに異なる方向から接続されていても良い。
　また、前記排出流路２４が、前記試料導出流路２１から分岐するのではなく、前記試料導出流路２１とは全く別の流路として独立して設けられていても良い。 In FIG. 6, the sample supply flow path 20 and the zero water supply flow path 22 are connected to the measurement cell 19 via the same pipe, but the sample supply flow path 20 and the zero water supply flow path 22 are completely mutually complete. Independent tubes may be used, and the flow paths 20 and 22 may be connected to the measurement cell from different directions.
Further, the discharge flow path 24 may not be branched from the sample lead-out flow path 21, but may be provided independently as a flow path completely separate from the sample lead-out flow path 21.
　隔膜を保護する保護膜１７を別途設けずに、例えば、前述した容器１ａの先端部分が、保護部材として隔膜１１が中間膜１２と接触する領域をさけるように、隔膜１１を覆うものとしても良い。 Without separately providing the protective film 17 for protecting the diaphragm, for example, the tip portion of the container 1a described above may cover the diaphragm 11 as a protective member so as to avoid the region where the diaphragm 11 contacts the interlayer film 12. ..
　前記実施形態では、内部液が過酢酸と反応しない緩衝液であるものを挙げたが、内部液がヨウ素イオンや臭化物イオンを含有する隔膜式過酢酸濃度計であってもよい。 In the above embodiment, the internal solution is a buffer solution that does not react with peracetic acid, but the internal solution may be a diaphragm-type peracetic acid concentration meter containing iodine ions and bromide ions.
　以下に実施例を掲げて本発明を更に詳細に説明するが、本発明はこれら実施例のみに限定されるものではない。
　この実施例では、同一形状の過酢酸濃度計であり、内部液中に触媒を備えた過酢酸濃度計（実施例１）と内部液中に触媒を備えていない過酢酸濃度計（比較例１）とを用いて過酢酸濃度測定を行い、それぞれの測定誤差を調べた。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
In this example, the peracetic acid concentration meter has the same shape and has a peracetic acid concentration meter having a catalyst in the internal liquid (Example 1) and a peracetic acid concentration meter having no catalyst in the internal liquid (Comparative Example 1). ) And the peracetic acid concentration was measured, and the measurement error of each was investigated.
＜実施例１＞
　実施例１では、前記実施形態で詳しく説明した、内部液中にカタラーゼを含有する過酢酸濃度計を使用した。本実施例では、内部液としてＫＣｌを１ｍｏｌ／Ｌとなるように溶解したリン酸緩衝液（ｐＨ７．０）に、カタラーゼを０.２Ｕ／ｍｇとなるように添加したものを使用した。
　測定対象として、過酢酸は含有するが過酸化水素を含有しない試料溶液と過酢酸と過酸化水素とを含有する試料溶液とを用意した。過酢酸と過酸化水素とを含有する試料溶液としては、０．０％から３．５％までの範囲で過酸化水素濃度を様々に変化させた試料溶液を用意した。
　これら各試料溶液の過酢酸濃度を、前述した過酢酸濃度計を使用して測定した。
　過酢酸濃度計で測定したものと同じ試料溶液の過酢酸濃度を並行して滴定法で測定した。過酢酸濃度計で測定された濃度指示値と、中和滴定により過酢酸濃度を正確に測定する滴定法で測定した濃度指示値との差を測定誤差とした。滴定法での過酢酸濃度測定は、平沼産業製ＣＯＭ－１７００を用いて行った。実験は２回行った。１回目の結果を図７(a)に、２回目の結果を図７(b)にそれぞれ示す。図７のグラフの縦軸は測定誤差を表し、横軸は試料溶液に含有される過酸化水素の濃度を表している。 <Example 1>
In Example 1, a peracetic acid densitometer containing catalase in the internal liquid, which was described in detail in the above embodiment, was used. In this example, a phosphate buffer solution (pH 7.0) in which KCl was dissolved so as to be 1 mol / L was used as the internal solution, and catalase was added so as to be 0.2 U / mg.
As measurement targets, a sample solution containing peracetic acid but not hydrogen peroxide and a sample solution containing peracetic acid and hydrogen peroxide were prepared. As a sample solution containing peracetic acid and hydrogen peroxide, a sample solution in which the hydrogen peroxide concentration was variously changed in the range of 0.0% to 3.5% was prepared.
The peracetic acid concentration of each of these sample solutions was measured using the above-mentioned peracetic acid concentration meter.
The peracetic acid concentration of the same sample solution as that measured by the peracetic acid concentration meter was measured in parallel by the titration method. The difference between the concentration indicated value measured by the peracetic acid densitometer and the concentration indicated value measured by the titration method for accurately measuring the peracetic acid concentration by neutralization titration was defined as the measurement error. The peracetic acid concentration was measured by the titration method using COM-1700 manufactured by Hiranuma Sangyo. The experiment was performed twice. The results of the first time are shown in FIG. 7 (a), and the results of the second time are shown in FIG. 7 (b). The vertical axis of the graph of FIG. 7 represents the measurement error, and the horizontal axis represents the concentration of hydrogen peroxide contained in the sample solution.
＜比較例１＞
　比較例１では、内部液にカタラーゼが含有されていない点以外は、実施例１で使用したものと全く同じ過酢酸濃度計を使用した。実施例１と同様の手順で測定誤差を算出した。実験は２回行った。１回目の結果を図７(a)に、２回目の結果を図７(b)にそれぞれ示す。 <Comparative example 1>
In Comparative Example 1, the same peracetic acid concentration meter as that used in Example 1 was used except that the internal solution did not contain catalase. The measurement error was calculated by the same procedure as in Example 1. The experiment was performed twice. The results of the first time are shown in FIG. 7 (a), and the results of the second time are shown in FIG. 7 (b).
　図７のグラフを見ればすぐにわかるように、内部液に過酸化水素を分解する触媒を添加することによって、過酢酸濃度計による過酢酸濃度の測定誤差が大幅に低減されることが分かった。
　比較例１では、試料溶液中に過酸化水素が含まれていると測定誤差が生じ、過酸化水素の濃度が高くなるにつれて測定誤差が非常に大きくなってしまうことがわかる。
　これに対して、内部液中に過酸化水素を分解する触媒を備えている実施例１では、測定誤差を試料溶液中の過酸化水素濃度に関わらず最大でも７０ｐｐｍ未満に抑えることができた。この測定誤差は、滴定法による過酢酸濃度の測定誤差も考慮すれば、ほとんど測定誤差がないといえる。
　また、前述した比較例の過酢酸濃度計では、過酢酸を含有しない試料溶液の次に過酢酸を含有する試料溶液を測定した場合、指示値がだらだらと上昇する現象が観察されたが、前記実施例の過酢酸濃度計ではこのよう場合であっても指示値が素早く安定することが分かった。この結果から、内部液に過酸化水素を分解する触媒を添加して、過酸化水素による過酢酸測定の指示値への影響を抑えることにより、過酢酸濃度測定の応答速度をも改善できることが分かった。 As can be seen immediately from the graph of FIG. 7, it was found that the error in measuring the peracetic acid concentration by the peracetic acid concentration meter was significantly reduced by adding the catalyst that decomposes hydrogen peroxide to the internal liquid. ..
In Comparative Example 1, it can be seen that if hydrogen peroxide is contained in the sample solution, a measurement error occurs, and the measurement error becomes very large as the concentration of hydrogen peroxide increases.
On the other hand, in Example 1 in which the catalyst for decomposing hydrogen peroxide in the internal solution was provided, the measurement error could be suppressed to less than 70 ppm at the maximum regardless of the concentration of hydrogen peroxide in the sample solution. It can be said that there is almost no measurement error in this measurement error, considering the measurement error of the peracetic acid concentration by the titration method.
Further, in the peracetic acid densitometer of the comparative example described above, when the sample solution containing peracetic acid was measured next to the sample solution containing no peracetic acid, the phenomenon that the indicated value gradually increased was observed. In the peracetic acid concentration meter of the example, it was found that the indicated value quickly became stable even in such a case. From this result, it was found that the response speed of peracetic acid concentration measurement can also be improved by adding a catalyst that decomposes hydrogen peroxide to the internal liquid to suppress the influence of hydrogen peroxide on the indicated value of peracetic acid measurement. It was.
　以上の結果から、内部液中に過酸化水素を分解する触媒を備えている過酢酸濃度計によれば、触媒を備えない場合に比べて、過酸化水素を含有する試料溶液の過酢酸濃度を測定する場合の測定誤差を大幅に削減できることが分かった。 From the above results, according to the peracetic acid concentration meter equipped with a catalyst that decomposes hydrogen peroxide in the internal liquid, the peracetic acid concentration of the sample solution containing hydrogen peroxide can be determined as compared with the case without a catalyst. It was found that the measurement error when measuring can be significantly reduced.
　本発明に係る過酢酸濃度計及び過酢酸濃度測定装置によれば、過酢酸濃度測定における誤差を小さく抑えて、従来よりも精度よく過酢酸濃度を測定することができる。 According to the peracetic acid concentration meter and the peracetic acid concentration measuring device according to the present invention, the error in the peracetic acid concentration measurement can be suppressed to a small value, and the peracetic acid concentration can be measured more accurately than before.

Claims (7)

  1. 　試料溶液の過酢酸濃度を測定する隔膜式の過酢酸濃度計であって、
    　過酢酸を透過する隔膜と、
    　前記隔膜を透過した過酢酸が溶解する内部液と、
    　前記内部液に浸漬する作用極及び対極と、
    　前記内部液中に含まれる過酸化水素を分解する触媒とを具備することを特徴とする過酢酸濃度計。     A diaphragm-type peracetic acid concentration meter that measures the peracetic acid concentration of a sample solution.
    A diaphragm that permeates peracetic acid and
    The internal liquid in which the peracetic acid that has passed through the diaphragm dissolves,
    The working electrode and the counter electrode immersed in the internal liquid,
    A peracetic acid concentration meter comprising a catalyst for decomposing hydrogen peroxide contained in the internal liquid.
  2. 　前記触媒がカタラーゼであることを特徴とする請求項１記載の過酢酸濃度計。 The peracetic acid concentration meter according to claim 1, wherein the catalyst is catalase.
  3. 前記内部液が、水素イオン濃度に対して緩衝作用を有する緩衝液であり、
    　前記内部液又は該内部液を収容するケーシングが、防腐剤又は抗菌成分を含有するものである請求項１又は２記載の過酢酸濃度計。     The internal solution is a buffer solution having a buffering action against hydrogen ion concentration.
    The peracetic acid concentration meter according to claim 1 or 2, wherein the internal liquid or a casing containing the internal liquid contains a preservative or an antibacterial component.
  4. 　前記隔膜における試料溶液と接触する側の表面に導電性メッシュ層をさらに備える請求項１乃至３のいずれか一項に記載の過酢酸濃度計。 The peracetic acid densitometer according to any one of claims 1 to 3, further comprising a conductive mesh layer on the surface of the diaphragm on the side in contact with the sample solution.
  5. 　請求項１乃至４のいずれか一項に記載の過酢酸濃度計と、
    　前記過酢酸濃度計に対して紫外線を照射する光源とを備える過酢酸濃度測定装置。     The peracetic acid concentration meter according to any one of claims 1 to 4.
    A peracetic acid concentration measuring device including a light source that irradiates the peracetic acid concentration meter with ultraviolet rays.
  6. 　請求項１乃至４のいずれか一項に記載の過酢酸濃度計と、
    　該過酢酸濃度計を内部に収容する測定セルと、
    　該測定セルに測定対象である試料溶液を供給する試料供給流路と、
    　過酢酸を含有しない液体又は気体を前記測定セルに供給するゼロ水供給流路と、
    　これら試料供給流路及びゼロ水供給流路を前記測定セルに切り替え可能に接続する切替機構とを備えている過酢酸濃度測定装置。     The peracetic acid concentration meter according to any one of claims 1 to 4.
    A measuring cell containing the peracetic acid concentration meter inside,
    A sample supply flow path for supplying the sample solution to be measured to the measurement cell,
    A zero water supply channel that supplies a liquid or gas containing no peracetic acid to the measurement cell,
    A peracetic acid concentration measuring device including a switching mechanism for connecting the sample supply flow path and the zero water supply flow path to the measurement cell in a switchable manner.
  7. 　請求項１乃至４のいずれか一項に記載の過酢酸濃度計を用いて過酢酸濃度を測定する方法であって、
    　過酢酸濃度測定を終了した後、次の過酢酸濃度測定を開始する前に、前記過酢酸濃度計の前記隔膜に、過酢酸を含有しない液体又は気体を所定時間の間供給することを特徴とする過酢酸濃度測定方法。     A method for measuring a peracetic acid concentration using the peracetic acid concentration meter according to any one of claims 1 to 4.
    After the peracetic acid concentration measurement is completed and before the next peracetic acid concentration measurement is started, the peracetic acid-free liquid or gas is supplied to the diaphragm of the peracetic acid concentration meter for a predetermined time. Peracetic acid concentration measurement method.
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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS593345A (en) * 1982-06-30 1984-01-10 Hitachi Ltd Dissolved oxygen meter equipped with electrode for removing interfering component
JPH0445798A (en) * 1990-06-08 1992-02-14 Hiranuma Sangyo Kk Fractional determination of hydrogen peroxide and peracetic acid
JPH04346063A (en) * 1991-05-24 1992-12-01 Hitachi Ltd Oxygen sensor and analysis device using it
US5770039A (en) * 1996-05-03 1998-06-23 Ecolab Inc. Method and apparatus for measuring and controlling active oxygen concentration in a bleach environment
JP2001235443A (en) * 2000-02-22 2001-08-31 Matsushita Electric Ind Co Ltd Ph sensor and ion water generator with the same
JP2006078260A (en) * 2004-09-08 2006-03-23 Horiba Ltd Residual chlorine meter and water-supply terminal monitor using it
JP2008026313A (en) * 2006-06-21 2008-02-07 Horiba Ltd Reference electrode, and composite electrode
JP2009069025A (en) * 2007-09-13 2009-04-02 Dkk Toa Corp Diaphragm type hydrogen peroxide electrode
JP2015230173A (en) * 2014-06-03 2015-12-21 株式会社 堀場アドバンスドテクノ Peracetic acid concentration meter
JP2015230172A (en) * 2014-06-03 2015-12-21 株式会社 堀場アドバンスドテクノ Membrane-type sensor and liquid analyzer

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4346063B2 (en) 2002-12-03 2009-10-14 大日本印刷株式会社 Transfer mask blank, transfer mask, and transfer method using the transfer mask

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS593345A (en) * 1982-06-30 1984-01-10 Hitachi Ltd Dissolved oxygen meter equipped with electrode for removing interfering component
JPH0445798A (en) * 1990-06-08 1992-02-14 Hiranuma Sangyo Kk Fractional determination of hydrogen peroxide and peracetic acid
JPH04346063A (en) * 1991-05-24 1992-12-01 Hitachi Ltd Oxygen sensor and analysis device using it
US5770039A (en) * 1996-05-03 1998-06-23 Ecolab Inc. Method and apparatus for measuring and controlling active oxygen concentration in a bleach environment
JP2001235443A (en) * 2000-02-22 2001-08-31 Matsushita Electric Ind Co Ltd Ph sensor and ion water generator with the same
JP2006078260A (en) * 2004-09-08 2006-03-23 Horiba Ltd Residual chlorine meter and water-supply terminal monitor using it
JP2008026313A (en) * 2006-06-21 2008-02-07 Horiba Ltd Reference electrode, and composite electrode
JP2009069025A (en) * 2007-09-13 2009-04-02 Dkk Toa Corp Diaphragm type hydrogen peroxide electrode
JP2015230173A (en) * 2014-06-03 2015-12-21 株式会社 堀場アドバンスドテクノ Peracetic acid concentration meter
JP2015230172A (en) * 2014-06-03 2015-12-21 株式会社 堀場アドバンスドテクノ Membrane-type sensor and liquid analyzer

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