JP6326473B2 - Ion selective electrode - Google Patents
Ion selective electrode Download PDFInfo
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- JP6326473B2 JP6326473B2 JP2016203062A JP2016203062A JP6326473B2 JP 6326473 B2 JP6326473 B2 JP 6326473B2 JP 2016203062 A JP2016203062 A JP 2016203062A JP 2016203062 A JP2016203062 A JP 2016203062A JP 6326473 B2 JP6326473 B2 JP 6326473B2
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Classifications
-
- 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
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/333—Ion-selective electrodes or membranes
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Description
この発明は、感応部の電気抵抗が小さく、応答精度に優れるとともに、機械的強度の向上が図れる上、感応部の形状の自由度が高く、製造が容易であるイオン選択性電極に関するものである。 The present invention relates to an ion-selective electrode that has a small electric resistance of a sensitive part, excellent response accuracy, can improve mechanical strength, has a high degree of freedom in the shape of the sensitive part, and is easy to manufacture. .
従来、pH電極等のイオン選択性電極としては、感応部に応答ガラス膜を備えたガラス電極が用いられている。このような応答ガラス膜には、アルカリ誤差や酸誤差が小さいこと、電気抵抗が小さいこと、応答性がよいこと、化学的耐久性が高いこと、電位勾配が理論値に近いこと、機械的強度が大きいこと、加工が容易であること等の諸性質が要求される。 Conventionally, as an ion selective electrode such as a pH electrode, a glass electrode provided with a response glass membrane in a sensitive part is used. Such response glass film has low alkali error and acid error, low electrical resistance, good response, high chemical durability, potential gradient close to the theoretical value, mechanical strength And various properties such as being easy to process are required.
これらの性質のうち、電気抵抗を小さくすることが可能となれば、応答性の向上、電気配線部分に高絶縁性が必要とされない、コネクタにフッ素系樹脂等の高価格材料を用いなくても済む、周囲の静電影響が少なくノイズが入らない、電気回路の簡素化によるpH計の小型化が図れる等の種々の効果を得ることが可能となる。 Of these properties, if it is possible to reduce the electrical resistance, the responsiveness is improved, high insulation is not required for the electrical wiring portion, and it is not necessary to use high-priced materials such as fluororesin for the connector. It is possible to obtain various effects such as a small influence on the surroundings, no noise, and the simplification of the electric circuit to reduce the size of the pH meter.
しかしながら、従来のガラス電極に用いられる応答ガラス膜の電気抵抗は、ρ=1×1010Ωcmと高く、依然として不充分なものである。 However, the electrical resistance of the response glass film used for the conventional glass electrode is as high as ρ = 1 × 10 10 Ωcm, which is still insufficient.
また、機械的強度に関しては、一般的な応答ガラス膜は、適切な粘度になるように加熱した応答ガラスをガラス製の支持管の開放端に融着させてから、この応答ガラスの塊をブロー成形によって膨出することにより形成される。 Regarding mechanical strength, a general response glass film is prepared by fusing a response glass heated to an appropriate viscosity to the open end of a glass support tube, and then blowing the mass of the response glass. It is formed by swelling by molding.
このような半球状の応答ガラス膜は、膜厚が略一定になるように、熟練した職人によって作製されるものであるが、ガラス電極の応答性を良くするためにはその面積はできるだけ大きく、その膜厚はできるだけ薄いことが好ましい。 Such a hemispherical response glass film is produced by a skilled craftsman so that the film thickness is substantially constant, but in order to improve the response of the glass electrode, its area is as large as possible, The film thickness is preferably as thin as possible.
しかしながら、膜厚が薄く応答性に優れた応答ガラス膜は、機械的強度が小さく、破損しやすいという問題を有している(特許文献1及び2参照)。 However, the response glass film having a thin film thickness and excellent responsiveness has a problem that it has a low mechanical strength and is easily damaged (see Patent Documents 1 and 2).
また、応答ガラス膜をブロー成形する場合、応答ガラスの性質等から加工が難しく、適切な強度を有し、かつ、応答性のよいガラス電極を製造するためには、高度な熟練を有する職人に頼らざるを得ず、このため、製造工程を自動化し生産性の向上を図ることが難しく、このことが製造コストを引き上げる要因となっている(特許文献3参照)。 In addition, when blow-molding a responsive glass film, it is difficult to process due to the nature of the responsive glass, etc., and in order to produce a glass electrode with appropriate strength and good responsiveness, a highly skilled craftsman is required. For this reason, it is difficult to automate the manufacturing process and improve productivity, which increases the manufacturing cost (see Patent Document 3).
そこで本発明は、感応部の電気抵抗が小さく、応答精度に優れるとともに、機械的強度の向上が図れる上、感応部の形状の自由度が高く、製造が容易であるイオン選択性電極を提供すべく図ったものである。 Therefore, the present invention provides an ion-selective electrode that has a small electrical resistance of the sensitive part, excellent response accuracy, can improve mechanical strength, has a high degree of freedom in the shape of the sensitive part, and is easy to manufacture. This is what I wanted.
本発明者が、従来のガラス電極の応答ガラス膜の代わりに、SUS等の電子伝導性材料からなる支持板に二酸化チタン(TiO2)や、二酸化ジルコニウム(ZrO2)等の遷移金属酸化物、又は、酸化アルミニウム(Al2O3)、二酸化ケイ素(SiO2)等の典型金属酸化物をコートしてなる感応部を使用して電極を作製し、イオン濃度の測定を行ったところ、予期せぬことに、このような電極は優れたイオン応答性を示すことが判明した。本発明は、このような新規な知見に基づき完成されたものである。 Instead of the conventional glass electrode responsive glass film, the present inventor uses a transition metal oxide such as titanium dioxide (TiO 2 ) or zirconium dioxide (ZrO 2 ) on a support plate made of an electron conductive material such as SUS, Alternatively, an electrode was prepared using a sensitive part coated with a typical metal oxide such as aluminum oxide (Al 2 O 3 ) or silicon dioxide (SiO 2 ), and the ion concentration was measured. In particular, it has been found that such an electrode exhibits excellent ion response. The present invention has been completed based on such novel findings.
すなわち本発明に係るイオン選択性電極は、内部電極と、前記内部電極に接する内部液と、前記内部液に接する面及び試料溶液に接する面を有する感応部とを備えたものであって、前記感応部が、電子伝導性支持体と、前記電子伝導性支持体上であって前記試料溶液と接する面に形成された金属酸化物を含有する膜とを備えており、前記金属酸化物が、二酸化チタン、二酸化ジルコニウム、酸化アルミニウム、及び、二酸化ケイ素からなる群より選ばれる少なくとも1種の化合物であることを特徴とする。 That is, an ion selective electrode according to the present invention includes an internal electrode, an internal liquid in contact with the internal electrode, and a sensitive part having a surface in contact with the internal liquid and a surface in contact with the sample solution, The sensitive part includes an electron conductive support, and a film containing a metal oxide formed on the surface of the electron conductive support that is in contact with the sample solution. It is at least one compound selected from the group consisting of titanium dioxide, zirconium dioxide, aluminum oxide, and silicon dioxide.
このようなものであれば、イオン選択性電極の感応部が、電子伝導性材料からなる支持体と、その上に形成された前記金属酸化物を含有する膜とから構成されるので、従来のガラス電極と比較して感応部の電気抵抗を減少させることが可能となり、これにより、感応部の応答精度の向上、応答時間の短縮をはじめとする種々の効果を得ることが可能となる。また、感応部の応答精度が向上することにより、電気回路が簡素で感度の低いpH計であっても、感応部に発生した電位差を良好に検知することが可能となる。 If it is such, since the sensitive part of an ion selective electrode is comprised from the support body which consists of an electron-conductive material, and the film | membrane containing the said metal oxide formed on it, since it is conventional, Compared with the glass electrode, it is possible to reduce the electric resistance of the sensitive part, and thereby various effects such as improvement of the response accuracy of the sensitive part and shortening of the response time can be obtained. Further, by improving the response accuracy of the sensitive part, it is possible to satisfactorily detect the potential difference generated in the sensitive part even if the electric circuit is simple and has a low sensitivity.
更に、本発明に係るイオン選択性電極を製造するには、従来の応答ガラス膜を製造する際に必要とされたような、熟練した職人によるブロー成形が不要であるので、製造工程の自動化も可能であり、製造コストを低減することが可能となる。 Furthermore, since the ion-selective electrode according to the present invention does not require blow molding by a skilled craftsman, which is necessary when manufacturing a conventional response glass membrane, the manufacturing process can be automated. This is possible, and the manufacturing cost can be reduced.
また、本発明に係るイオン選択性電極は、ブロー成形された半球状の薄い応答ガラス膜を感応部とする従来のガラス電極に比べて、感応部を破損しにくいものとすることができるとともに、感応部の形状の自由度も向上しうる。 In addition, the ion-selective electrode according to the present invention can make the sensitive part less likely to be damaged than a conventional glass electrode having a sensitive part made of a blown hemispherical thin response glass membrane, The degree of freedom of the shape of the sensitive part can also be improved.
更に、前記金属酸化物が、二酸化チタンや、二酸化ジルコニウムである場合、感応部に紫外線等を照射することにより、これらの金属酸化物に光触媒活性を発現させることができるので、感応部への汚れの付着を防止するとともに、付着した汚れを容易に除去することができるので、汚れに起因した不斉電位の発生を防止することができる。 Further, when the metal oxide is titanium dioxide or zirconium dioxide, the photocatalytic activity can be expressed in these metal oxides by irradiating the sensitive part with ultraviolet rays or the like. And the attached dirt can be easily removed, so that the generation of an asymmetric potential due to the dirt can be prevented.
二酸化チタン等の金属酸化物は負に帯電しやすいため、感応部の試料溶液と接する側の面だけに前記金属酸化物を含有する膜が形成されていると、この負の電荷に起因して不斉電位が生じ、イオン濃度の正確な測定が阻害される場合がある。しかしながら、前記感応部が、更に、前記電子伝導性支持体上であって前記内部液と接する面に形成された前記金属酸化物を含有する膜も備えていると、試料溶液と接する面と内部液と接する面との電荷が釣り合うことにより、感応部において不斉電位が生じにくくなる。また、感応部の内部液と接する面にも二酸化チタン等の前記金属酸化物を含有する膜が形成されていると、電子伝導性支持体が金属からなる場合であっても、電子伝導性支持体が酸化することに由来する酸化還元電位の発生や酸化膜(錆)の形成を防ぐことができるので、これによっても不斉電位の発生を防止することができる。 Since metal oxides such as titanium dioxide are likely to be negatively charged, if a film containing the metal oxide is formed only on the surface of the sensitive part that is in contact with the sample solution, it is caused by this negative charge. An asymmetric potential may be generated and accurate measurement of ion concentration may be hindered. However, when the sensitive part further includes a film containing the metal oxide formed on the surface that is in contact with the internal liquid on the electron conductive support, the surface in contact with the sample solution and the internal As the charges on the surface in contact with the liquid are balanced, an asymmetric potential is less likely to occur in the sensitive part. In addition, when a film containing the metal oxide such as titanium dioxide is formed on the surface of the sensitive part that contacts the internal liquid, the electron conductive support is supported even when the electron conductive support is made of metal. Since it is possible to prevent the generation of an oxidation-reduction potential and the formation of an oxide film (rust) derived from the oxidation of the body, it is also possible to prevent the generation of an asymmetric potential.
前記電子伝導性支持体の材料としては、例えば、金属、導電性高分子、電子伝導性ガラス等が挙げられるが、例えば、前記電子伝導性支持体が金属からなるものであると、感応部の機械的強度が向上し、破損しにくくなるとともに、感応部の形状を自由に選択することが可能となる。 Examples of the material for the electron conductive support include metals, conductive polymers, and electron conductive glass. For example, if the electron conductive support is made of a metal, The mechanical strength is improved and it becomes difficult to break, and the shape of the sensitive part can be freely selected.
また、前記金属のうち、例えば、一般にSUSと称されるステンレス鋼等の鉄を含む合金は、電気抵抗が数kΩ以下と小さく、また、コストや、機械的強度、成形の容易さ、取り扱いの容易さ、人体への無害さ等の点から好適に用いられる。 Further, among the metals, for example, an alloy containing iron such as stainless steel generally called SUS has an electric resistance as small as several kΩ or less, and is low in cost, mechanical strength, ease of forming, and handling. It is preferably used in terms of ease and harmlessness to the human body.
このような本発明に係るイオン選択性電極は、例えば、pH電極や、pNa電極として用いることができる。 Such an ion selective electrode according to the present invention can be used as, for example, a pH electrode or a pNa electrode.
本発明に係るイオン選択性電極は、独立型の電極に限定されず、比較電極とともに一体化した複合電極や、複合電極に更に温度補償電極を加えて一体化した一本電極であってもよい。 The ion-selective electrode according to the present invention is not limited to a stand-alone electrode, and may be a composite electrode integrated with a comparative electrode, or a single electrode integrated by adding a temperature compensation electrode to the composite electrode. .
また、本発明に係るイオン選択性電極の形状についても特に限定されず、管状であってもよく、シート状であってもよい。 Further, the shape of the ion selective electrode according to the present invention is not particularly limited, and may be tubular or sheet-like.
このように本発明によれば、応答精度が向上するとともに、製造が容易でコストの低減が可能となり、また、感応部を破損しにくいものとすることができる上に、感応部にセルフクリーニング機能を発現させることも可能となる。 As described above, according to the present invention, the response accuracy is improved, the manufacturing is easy and the cost can be reduced, the sensitive part can be made less likely to be damaged, and the self-cleaning function is provided in the sensitive part. Can also be expressed.
<第1実施形態>
以下に、本発明の第1実施形態について図面を参照して説明する。
<First Embodiment>
A first embodiment of the present invention will be described below with reference to the drawings.
本実施形態に係るpH電極1は、図1及び図2に示すように、長手方向に直交する断面が矩形状である筒状の支持管2と、その支持管2の先端部23近傍の側面に形成された矩形状の感応部3とを備えている。 As shown in FIGS. 1 and 2, the pH electrode 1 according to the present embodiment includes a cylindrical support tube 2 having a rectangular cross section perpendicular to the longitudinal direction, and a side surface in the vicinity of the tip 23 of the support tube 2. And a rectangular-shaped sensitive part 3 formed in the above.
支持管2は、内部電極4と内部液5とを収容するものであり、例えば、塩化ビニル、ポリエチレン、ポリプロピレン、ポリエチレンテレフタレート、アクリル、ポリテトラフルオロエチレン、ポリフッ化ビニリデン、ポリエーテルエーテルケトン等の有機高分子材料や、石英ガラス、パイレックス(登録商標)ガラス等のガラス、セラミックスの無機材料等からなるものである。 The support tube 2 accommodates the internal electrode 4 and the internal liquid 5 and is, for example, an organic material such as vinyl chloride, polyethylene, polypropylene, polyethylene terephthalate, acrylic, polytetrafluoroethylene, polyvinylidene fluoride, or polyetheretherketone. It is made of a polymer material, glass such as quartz glass or Pyrex (registered trademark) glass, a ceramic inorganic material, or the like.
支持管2の基端部24には、内部液5が支持管2の外に漏れ出ないように、基端部24に液密に接触するシールパッキン21と、そのシールパッキン21に覆い被さるキャップ22とが設けられており、一方、支持管2の先端部23近傍の側面には貫通孔が形成されており、当該貫通孔には感応部3が嵌め込まれている。 At the base end portion 24 of the support tube 2, a seal packing 21 that comes into liquid-tight contact with the base end portion 24 so that the internal liquid 5 does not leak out of the support tube 2, and a cap that covers the seal packing 21. On the other hand, a through hole is formed in the side surface of the support tube 2 in the vicinity of the distal end portion 23, and the sensitive portion 3 is fitted in the through hole.
内部電極4は、例えば、銀/塩化銀(Ag/AgCl)電極等からなり、リード線6が接続されている。当該リード線6は、支持管2の基端部24からシールパッキン21及びキャップ22を介して、外部に延出し図示しないpH計本体に接続されるようにしてある。内部液5は、例えば、pH7に調整した塩化カリウム(KCl)溶液等からなるものである。 The internal electrode 4 is made of, for example, a silver / silver chloride (Ag / AgCl) electrode, and the lead wire 6 is connected thereto. The lead wire 6 extends outside from the base end portion 24 of the support tube 2 via the seal packing 21 and the cap 22 and is connected to a pH meter main body (not shown). The internal liquid 5 is made of, for example, a potassium chloride (KCl) solution adjusted to pH 7.
感応部3は、電子伝導性材料からなる支持板31の両面に、二酸化チタンを含有する膜32(以下、二酸化チタン膜32ともいう。)が形成された矩形板状のものであり、支持管2の先端部23近傍の側面に形成された貫通孔に嵌め込まれている。 The sensitive portion 3 is a rectangular plate having a film 32 containing titanium dioxide (hereinafter also referred to as a titanium dioxide film 32) formed on both surfaces of a support plate 31 made of an electron conductive material. 2 is fitted into a through-hole formed in a side surface near the tip 23.
支持板31を構成する電子伝導性材料としては特に限定されず、例えば、鉄、銅、白金、銀、金、アルミニウム、タンタル、チタン、イリジウム、及び、それらを含有する合金等の金属;ポリアセチレン、ポリフェニレン、ポリピロール、ポリチオフェン等の導電性高分子;チタノリン酸ガラス等の混合電子価を有する電子伝導性ガラス等が挙げられる。このうち、機械的強度や成形の容易さの点から金属が好適に用いられ、例えば、一般にSUSと称されるステンレス鋼は、電気抵抗が10kΩ以下程度と小さく、また、コストや、機械的強度、成形の容易さ、取り扱いの容易さ、人体への無害さ等の点で優れている。 The electron conductive material constituting the support plate 31 is not particularly limited. For example, metals such as iron, copper, platinum, silver, gold, aluminum, tantalum, titanium, iridium, and alloys containing them; polyacetylene, Examples thereof include conductive polymers such as polyphenylene, polypyrrole, and polythiophene; and electron conductive glass having a mixed electron valence such as titanophosphate glass. Of these, metals are preferably used from the viewpoint of mechanical strength and ease of molding. For example, stainless steel, generally called SUS, has a small electrical resistance of about 10 kΩ or less, and has low cost and mechanical strength. It is excellent in terms of ease of molding, ease of handling, harmlessness to the human body, and the like.
二酸化チタン膜32は、二酸化チタンを含有するものであるが、二酸化チタンの結晶構造には、正方晶系のアナターゼ型、ルチル型、斜方晶系のブルッカイト型があり、また非晶質(アモルファス型)の二酸化チタンも知られている。本実施形態における二酸化チタン膜32は、いずれの結晶型の二酸化チタンを含有するものであってもよいが、アナターゼ型の二酸化チタンは、イオン官能基として機能するOH基が他の結晶型のものよりも多いので、イオン応答性に優れている。二酸化チタン膜32の膜厚としては、200〜600nmであるのが好ましく、より好ましくは200〜300nmであるが、膜厚が1000nm以上であると、感度が悪くなる傾向がある。 The titanium dioxide film 32 contains titanium dioxide. The crystal structure of titanium dioxide includes tetragonal anatase type, rutile type, orthorhombic brookite type, and amorphous (amorphous). Type) titanium dioxide is also known. The titanium dioxide film 32 in the present embodiment may contain any crystal type titanium dioxide, but the anatase type titanium dioxide has an OH group that functions as an ion functional group in another crystal type. Therefore, the ion responsiveness is excellent. The thickness of the titanium dioxide film 32 is preferably 200 to 600 nm, and more preferably 200 to 300 nm. However, when the film thickness is 1000 nm or more, the sensitivity tends to deteriorate.
二酸化チタン膜32は、膜構造を形成する二酸化チタンとは別個に二酸化チタン微粒子を含有していてもよい。二酸化チタン膜32中に二酸化チタン微粒子が分散していると、二酸化チタン膜32の光触媒活性を調節又は増強することが可能となる。また、例えば、二酸化チタン膜32がゾルゲル法により形成されたものである場合は、その焼成工程において、不純物が混入することがあるが、このような場合に別途二酸化チタン微粒子が配合されていると、光触媒活性を補完することができる。なお、配合する二酸化チタン微粒子の粒径や結晶密度は、pH電極1の用途に合わせて適宜選択することができるが、二酸化チタン微粒子の粒径としては、10〜100nmであるのが好ましく、より好ましくは20〜40nmである。粒径が10nm未満であると凝集しやすくなり、一方、粒径が100nmを超えると沈殿しやすくなる。 The titanium dioxide film 32 may contain fine titanium dioxide particles separately from the titanium dioxide forming the film structure. When titanium dioxide fine particles are dispersed in the titanium dioxide film 32, the photocatalytic activity of the titanium dioxide film 32 can be adjusted or enhanced. Further, for example, when the titanium dioxide film 32 is formed by a sol-gel method, impurities may be mixed in the firing step. In such a case, if titanium dioxide fine particles are separately added, , Can complement the photocatalytic activity. The particle diameter and crystal density of the titanium dioxide fine particles to be blended can be appropriately selected according to the use of the pH electrode 1, but the particle diameter of the titanium dioxide fine particles is preferably 10 to 100 nm, more Preferably it is 20-40 nm. When the particle size is less than 10 nm, aggregation tends to occur, while when the particle size exceeds 100 nm, precipitation tends to occur.
二酸化チタン膜32は、また、コバルト、ニッケル、タングステン等の遷移金属を含有していてもよい。これらの遷移金属を二酸化チタン膜32に配合することにより、二酸化チタン膜32のアルカリ誤差を減少したり、二酸化チタンの奏する光触媒活性を増強したりすることが可能となる。 The titanium dioxide film 32 may also contain a transition metal such as cobalt, nickel, or tungsten. By blending these transition metals into the titanium dioxide film 32, it is possible to reduce the alkali error of the titanium dioxide film 32 and enhance the photocatalytic activity exhibited by titanium dioxide.
二酸化チタン膜32は、更に、銅、白金、金、銀等の貴金属を含有していてもよい。これらの貴金属を二酸化チタン膜32に配合することにより、二酸化チタン膜32内に酸化還元サイトを形成し、二酸化チタンの奏する光触媒活性を増強することが可能となる。また、鉄等の遷移金属を配合することにより、二酸化チタンに可視光領域においてまで分解応答させることが可能となる。 The titanium dioxide film 32 may further contain a noble metal such as copper, platinum, gold, or silver. By blending these noble metals into the titanium dioxide film 32, redox sites can be formed in the titanium dioxide film 32, and the photocatalytic activity exhibited by titanium dioxide can be enhanced. In addition, by incorporating a transition metal such as iron, it is possible to cause titanium dioxide to decompose and respond to the visible light region.
支持板31の表面に二酸化チタン膜32を形成する方法としては特に限定されないが、例えば、ゾルゲル法を用いることができる。この場合は、まず、必要に応じて、コバルト等の金属、二酸化チタン微粒子等の付加的成分を添加したチタンアルコキシド溶液にアルコールを添加して混合溶液を調製し、次に、この混合溶液に加水分解に必要な水、触媒として硝酸等を加えて出発溶液を調製する。この出発溶液を一定温度で攪拌してアルコキシドの加水分解と重縮合反応とを行い、チタンの水酸化物微粒子を生成しチタニアゾルを作る。得られたチタニアゾルをディップコーティング法等を用いて支持板31表面に塗布した後、乾燥し、焼成することにより、支持板31表面上に二酸化チタン膜32を形成することができる。そして、ディップコーティング条件(速度、回数)や焼成条件(温度、時間)を制御することにより、二酸化チタン膜32を緻密なものにしたり多孔質にしたりすることができる。 A method for forming the titanium dioxide film 32 on the surface of the support plate 31 is not particularly limited, and for example, a sol-gel method can be used. In this case, first, if necessary, a mixed solution is prepared by adding alcohol to a titanium alkoxide solution to which additional components such as a metal such as cobalt and titanium dioxide fine particles have been added. A starting solution is prepared by adding water necessary for decomposition and nitric acid as a catalyst. The starting solution is stirred at a constant temperature to perform alkoxide hydrolysis and polycondensation reaction to produce titanium hydroxide fine particles to produce a titania sol. The obtained titania sol is applied to the surface of the support plate 31 using a dip coating method or the like, then dried and baked, whereby the titanium dioxide film 32 can be formed on the surface of the support plate 31. The titanium dioxide film 32 can be made dense or porous by controlling dip coating conditions (speed, number of times) and baking conditions (temperature, time).
支持管2の先端部23近傍の側面に感応部3を形成するには、まず、両面に二酸化チタン膜32が形成された支持板31を、支持管2の先端部23近傍の側面に形成された貫通孔に嵌め込んで、次いで、電気絶縁性を有する接合剤を用いた熱融着手段や、電気絶縁性を有する接着剤を用いて、支持管2の貫通孔に支持板31を接合し封止する。前記接合剤としては、例えば、ポリオレフィン系、シリコーンレジン系等のものが用いられ、前記接着剤としては、例えば、シランカップリング剤等を含むシリコーン系、エポキシ系、ウレタン系等の有機高分子接着剤等が用いられる。 In order to form the sensitive part 3 on the side surface of the support tube 2 in the vicinity of the tip 23, first, a support plate 31 having a titanium dioxide film 32 formed on both sides is formed on the side of the support tube 2 in the vicinity of the tip 23. Next, the support plate 31 is joined to the through hole of the support tube 2 by using a heat fusion means using a bonding agent having electrical insulation or an adhesive having electrical insulation. Seal. Examples of the bonding agent include polyolefin-based and silicone resin-based adhesives. Examples of the adhesive include silicone-based, epoxy-based, urethane-based organic polymer adhesives including silane coupling agents. An agent or the like is used.
このようにして得られた感応部3に対し、LED、水素放電管、キセノン放電管、水銀ランプ、ルビーレーザ、YAGレーザ、エキシマレーザ、色素レーザ等を光源として、紫外線等の光を照射すると、二酸化チタン等の光触媒活性が誘起され、その酸化作用により付着した有機物等が分解され、かつ、超親水作用により付着物が剥離しやすい状態になる、いわゆるセルフクリーニング機能が発現する。 When the sensitive part 3 thus obtained is irradiated with light such as ultraviolet rays using a LED, a hydrogen discharge tube, a xenon discharge tube, a mercury lamp, a ruby laser, a YAG laser, an excimer laser, a dye laser or the like as a light source, A photocatalytic activity such as titanium dioxide is induced, an organic matter or the like attached by the oxidation action is decomposed, and a so-called self-cleaning function is exhibited in which the attached matter is easily peeled off by a superhydrophilic action.
本実施形態に係るpH電極1を用いて試料溶液のpHを測定するには、pH電極1の感応部3を、pHを求めたい試料溶液に浸すと、感応部3に内部液5と試料溶液との間のpHの差に応じた起電力が生じる。この起電力を、図示しない比較電極を用いて、pH電極1の内部電極4と比較電極の内部電極の電位差(電圧)として測定してpHを算出する。この起電力は温度によって変動するため、温度素子を用い、この出力信号値をパラメータとして前記電位差を補正して、試料溶液のpHを算出しpH計本体に表示すればよい。 In order to measure the pH of the sample solution using the pH electrode 1 according to the present embodiment, when the sensitive part 3 of the pH electrode 1 is immersed in the sample solution whose pH is to be obtained, the internal solution 5 and the sample solution are placed in the sensitive part 3. An electromotive force is generated according to the difference in pH between the two. The electromotive force is measured as a potential difference (voltage) between the internal electrode 4 of the pH electrode 1 and the internal electrode of the comparative electrode using a comparative electrode (not shown), and the pH is calculated. Since this electromotive force varies depending on temperature, a temperature element is used, the potential difference is corrected using the output signal value as a parameter, the pH of the sample solution is calculated, and displayed on the pH meter body.
このように構成した本実施形態に係るpH電極1によれば、その感応部3が、電子伝導性材料からなる支持板31と、その上に形成された二酸化チタン膜32とから構成されるので、感応部3の電気抵抗を減少させることが可能となり、これにより、優れた感度でpHを検出することができるとともに、電気配線部分に高絶縁性が必要とされない、コネクタにフッ素系樹脂等の高価格材料を用いなくても済む等の種々の効果を得ることが可能となる。 According to the pH electrode 1 according to the present embodiment configured as described above, the sensitive portion 3 includes the support plate 31 made of an electron conductive material and the titanium dioxide film 32 formed thereon. In addition, it is possible to reduce the electrical resistance of the sensitive portion 3, thereby detecting pH with excellent sensitivity, and high electrical insulation is not required in the electrical wiring portion, and the connector is made of a fluorine resin or the like. It is possible to obtain various effects such as eliminating the need for expensive materials.
また、感応部3の応答精度が向上することにより、電気回路が簡素で感度の低いpH計であっても感応部3に発生した電位差を良好に検知することが可能となる。このため、本実施形態に係るpH電極1を用いることにより、電気回路の簡素化によるpH計の小型化も実現しうる。 Further, by improving the response accuracy of the sensitive unit 3, it is possible to satisfactorily detect the potential difference generated in the sensitive unit 3 even if the electric circuit is simple and the pH meter is low in sensitivity. For this reason, by using the pH electrode 1 according to the present embodiment, it is possible to reduce the size of the pH meter by simplifying the electric circuit.
更に、本実施形態の感応部3を形成するには、従来の応答ガラス膜を製造する際に必要とされたような、熟練した職人によるブロー成形が不要であるので、製造工程の自動化も可能であり、製造コストを低減することが可能となる。 Furthermore, since the sensitive part 3 of this embodiment is formed, it is not necessary to perform blow molding by skilled craftsmen as required when manufacturing a conventional response glass film, so that the manufacturing process can be automated. Thus, the manufacturing cost can be reduced.
また、本実施形態に係るpH電極1は、ブロー成形された半球状の薄い応答ガラス膜を感応部3とする従来のガラス電極に比べて破損しにくいものとすることができる。 Further, the pH electrode 1 according to the present embodiment can be made less likely to break than a conventional glass electrode having a sensitive hemispherical response glass film that is blow-molded as the sensitive part 3.
更に、本実施形態によれば、感応部3に紫外線等を照射して二酸化チタンに光触媒活性を発現させることにより、感応部3への汚れの付着を防止するとともに、付着した汚れを除去することができるので、汚れに起因した不斉電位の発生を防止することができる。 Furthermore, according to this embodiment, the sensitive part 3 is irradiated with ultraviolet rays or the like to cause the titanium dioxide to exhibit photocatalytic activity, thereby preventing the dirt from adhering to the sensitive part 3 and removing the adhered dirt. Therefore, the generation of an asymmetric potential due to contamination can be prevented.
また、二酸化チタンは負に帯電しやすいため、感応部3の試料溶液と接する側の面だけに二酸化チタン膜32が形成されていると、この負の電荷に起因して不斉電位が生じ、pHの正確な測定が阻害される場合があるが、本実施形態では、支持板31の両面に対称に二酸化チタン膜32が形成されているので、試料溶液と接する面と内部液5と接する面との電荷が釣り合うことにより、感応部3において不斉電位が生じにくくなる。また、感応部3の内部液5と接する面にも二酸化チタン膜32が形成されていることにより、支持板31がSUS等の金属からなる場合であっても、支持板31が酸化して酸化膜(錆)が形成されるのを防ぐことができるので、これによっても不斉電位の発生を防止することができる。 Further, since titanium dioxide is easily negatively charged, if the titanium dioxide film 32 is formed only on the surface of the sensitive portion 3 that is in contact with the sample solution, an asymmetric potential is generated due to this negative charge, Although accurate measurement of pH may be hindered, in this embodiment, since the titanium dioxide film 32 is formed symmetrically on both surfaces of the support plate 31, the surface in contact with the sample solution and the surface in contact with the internal liquid 5. As a result, the asymmetric potential is hardly generated in the sensitive part 3. Further, since the titanium dioxide film 32 is also formed on the surface of the sensitive portion 3 that contacts the internal liquid 5, even when the support plate 31 is made of a metal such as SUS, the support plate 31 is oxidized and oxidized. Since formation of a film (rust) can be prevented, the generation of an asymmetric potential can also be prevented by this.
更に、本実施形態における感応部3は電気抵抗が小さいので、支持管2に従来のガラス電極のような高い絶縁性は必要とされず、より安価な材料を使用することができる。このため、例えば、支持管2を塩化ビニルから構成し、支持板31としてSUSからなるものを用いれば、極めて安価にpH電極1を作製することができる。 Furthermore, since the sensitive part 3 in this embodiment has a small electrical resistance, the support tube 2 does not require high insulation as in the case of a conventional glass electrode, and a cheaper material can be used. For this reason, for example, if the support tube 2 is made of vinyl chloride and the support plate 31 made of SUS is used, the pH electrode 1 can be manufactured at a very low cost.
また、本実施形態では、支持管2の側面に感応部3が設けてあるので、底面(先端面)を実験台等の上に置いて起立させることも可能である。 Moreover, in this embodiment, since the sensitive part 3 is provided in the side surface of the support tube 2, it is also possible to stand by placing the bottom surface (tip surface) on an experimental table or the like.
<第2実施形態>
次に、本発明の第2実施形態について図面を参照して説明する。なお、以下においては、第1実施形態と異なる点を中心に説明する。
Second Embodiment
Next, a second embodiment of the present invention will be described with reference to the drawings. In the following, description will be made centering on differences from the first embodiment.
本実施形態に係るpH電極1は、図3及び図4に示すように、支持管2と感応部3との接合が機械的な機構(メカニカルシール)によるものである。本実施形態では、円筒状の支持管2の先端部23は、外径が小さくなっており、その先端部23の外周面には、後述する膜固定部24が螺合される雄ねじ部23aが設けられている。また、先端部23の先端面には、Oリング25を収容するための収容溝23bが、支持管2の中心軸と同心円上に設けられている。そして、その先端面に覆い被さるように、その直径が支持管2の先端面と略合致する大きさである円盤状に形成された感応部3が設けられている。 In the pH electrode 1 according to this embodiment, as shown in FIGS. 3 and 4, the support tube 2 and the sensitive portion 3 are joined by a mechanical mechanism (mechanical seal). In the present embodiment, the distal end portion 23 of the cylindrical support tube 2 has a small outer diameter, and a male screw portion 23a to which a membrane fixing portion 24 described later is screwed is formed on the outer peripheral surface of the distal end portion 23. Is provided. In addition, an accommodation groove 23 b for accommodating the O-ring 25 is provided on the distal end surface of the distal end portion 23 concentrically with the central axis of the support tube 2. And the sensitive part 3 formed in the disk shape whose diameter is the magnitude | size which substantially corresponds with the front end surface of the support tube 2 is provided so that the front end surface may be covered.
感応部3は、支持管2の先端面との間に弾性体であるOリング25を挟み込み、支持管2の先端面に膜固定部24によって固定されている。なお、Oリング25の材料としては、耐薬品性を有するフッ素系ゴムやフッ素系樹脂等が挙げられる。 The sensitive portion 3 is sandwiched between an O-ring 25 that is an elastic body between the front end surface of the support tube 2 and is fixed to the front end surface of the support tube 2 by a membrane fixing portion 24. Examples of the material of the O-ring 25 include chemical-resistant fluorine rubber and fluorine resin.
膜固定部24は、感応部3をその一部が外部に露出するように、支持管2の先端面に固定するためのものであり、円筒状をなすものである。その内周面には、先端部23の外周面に設けた雄ねじ部23aに螺合する雌ねじ部241と、その雄ねじ部23aと雌ねじ部241が螺合したときにOリング25を介して感応部3を支持管2の先端面に押圧する押圧面242とを備えている。そして、押圧面242は膜固定部24の内周面に設けられた、Oリング25を収容するための収容溝24bの底面に設けられている。 The membrane fixing part 24 is for fixing the sensitive part 3 to the distal end surface of the support tube 2 so that a part of the sensitive part 3 is exposed to the outside, and has a cylindrical shape. The inner peripheral surface has a female screw portion 241 screwed into a male screw portion 23a provided on the outer peripheral surface of the tip portion 23, and a sensitive portion via an O-ring 25 when the male screw portion 23a and the female screw portion 241 are screwed together. And a pressing surface 242 that presses 3 against the distal end surface of the support tube 2. The pressing surface 242 is provided on the bottom surface of the accommodation groove 24 b provided on the inner peripheral surface of the membrane fixing portion 24 for accommodating the O-ring 25.
本実施形態に係るpH電極1を組み立てるには、図4に示すように、先端部23の収容溝23bと膜固定部24の収容溝24bとにOリング25を嵌め込み、その後、感応部3が先端部23と膜固定部24との間に挟まれるように、膜固定部24に設けた雌ねじ部241を先端部23の外周面に設けた雄ねじ部23aに螺合させる。 In order to assemble the pH electrode 1 according to the present embodiment, as shown in FIG. 4, the O-ring 25 is fitted into the accommodation groove 23 b of the distal end portion 23 and the accommodation groove 24 b of the membrane fixing portion 24. The female screw portion 241 provided on the membrane fixing portion 24 is screwed into the male screw portion 23 a provided on the outer peripheral surface of the tip portion 23 so as to be sandwiched between the tip portion 23 and the membrane fixing portion 24.
このように構成した本実施形態に係るpH電極1によれば、感応部3が劣化した場合は、感応部3だけを取り外して取替えることができる。このため、コストを抑えつつ、高い精度の測定を継続して行うことができる。 According to the pH electrode 1 according to the present embodiment configured as described above, when the sensitive part 3 is deteriorated, only the sensitive part 3 can be removed and replaced. For this reason, it is possible to continuously perform measurement with high accuracy while suppressing cost.
<第3実施形態>
続いて、本発明の第3実施形態について図面を参照して説明する。なお、以下においては、第1実施形態及び第2実施形態と異なる点を中心に説明する。
<Third Embodiment>
Next, a third embodiment of the present invention will be described with reference to the drawings. In the following description, differences from the first embodiment and the second embodiment will be mainly described.
本実施形態に係るシート型複合電極10は、図5及び図6に示すように、pH電極と比較電極とが一体となったシート型のものであり、基板11と、基板11の上面に付着され、内部電極部121及びリード部122を備えた電極12と、基板11の上面に形成された支持層13と、支持層13に形成された孔131内に充填されたゲル状内部液14と、支持層13の上面に固着された平板状の感応部3及び液絡膜15とを備えている。 As shown in FIGS. 5 and 6, the sheet-type composite electrode 10 according to the present embodiment is a sheet-type electrode in which a pH electrode and a comparison electrode are integrated, and is attached to the substrate 11 and the upper surface of the substrate 11. The electrode 12 having the internal electrode part 121 and the lead part 122, the support layer 13 formed on the upper surface of the substrate 11, and the gel-like internal liquid 14 filled in the holes 131 formed in the support layer 13. The plate-shaped sensitive part 3 and the liquid junction film 15 fixed to the upper surface of the support layer 13 are provided.
基板11は、電気絶縁性を有する材料から構成されており、例えば、ポリエチレン、ポリプロピレン、ポリエチレンテレフタレート、アクリル、ポリテトラフルオロエチレン等の有機高分子材料や、石英ガラス、パイレックス(登録商標)ガラス等の無機材料等からなるものが挙げられる。 The substrate 11 is made of an electrically insulating material, such as an organic polymer material such as polyethylene, polypropylene, polyethylene terephthalate, acrylic, polytetrafluoroethylene, quartz glass, Pyrex (registered trademark) glass, or the like. The thing which consists of inorganic materials etc. is mentioned.
電極12は、その基板11の上面に内外2対が形成されており、例えば、電気良導体である銀、銅、金、白金、及び、その合金等のうちから選ばれた金属又はその金属を含むペーストや、IrO2、SnO2等の半導体を、真空蒸着法、CVD法等の物理的メッキ法、電解法、無電解法等の化学的メッキ法、シルクスクリー法、凸版法、平板法等の印刷法により付着形成したものである。なお、電極12を付着形成するまえに、必要に応じて、基板11の上面に、グラフト加工及びシランカップリング剤等を用いたアンカー処理を施してもよい。 The electrode 12 has two inner and outer pairs formed on the upper surface of the substrate 11, and includes, for example, a metal selected from silver, copper, gold, platinum, and alloys thereof, which are good electrical conductors, or the metal thereof. Paste and semiconductors such as IrO 2 and SnO 2 are applied to physical plating methods such as vacuum deposition and CVD, chemical plating methods such as electrolysis and electroless methods, silk screen methods, letterpress methods and plate methods. It is formed by adhesion by a printing method. Note that, before the electrode 12 is attached and formed, if necessary, the upper surface of the substrate 11 may be subjected to an anchoring process using a grafting process and a silane coupling agent.
なお、いずれの電極12においても、基板11の一端縁部に位置する基端部分はリード部122とされ、また、外側の一対の電極12における、基板11の略中央部に位置する略円形先端部分は、例えば、AgCl等の電極材料で被覆されて内部電極部121に形成され、内側の一対の電極12における基板11の略中央部に位置する先端部分間には、例えば、サーミスタ等の温度補償用電極部123が設けられている。 In any of the electrodes 12, a base end portion located at one end edge of the substrate 11 is a lead portion 122, and a substantially circular tip located at a substantially central portion of the substrate 11 in the pair of outer electrodes 12. The portion is covered with an electrode material such as AgCl, and is formed in the internal electrode portion 121. Between the front end portions of the pair of inner electrodes 12 located at the substantially central portion of the substrate 11, for example, the temperature of a thermistor or the like. A compensation electrode portion 123 is provided.
支持層13は、基板11の上面に形成されており、基板11と同様な電気絶縁性を有する材料からなり、かつ、両内部電極部121に対応する箇所に孔131を有するものである。支持層13は、全てのリード部122及びその周辺を露出させた状態で、基板11の上面に、例えば、スクリーン印刷法や、電気絶縁性を有する接合剤を用いた熱融着手段等を用いて形成されている。なお、この支持層13の上面にも、必要に応じて、グラフト加工及びシランカップリング剤等によるアンカー処理を施しておく。 The support layer 13 is formed on the upper surface of the substrate 11, is made of a material having the same electrical insulation as the substrate 11, and has holes 131 at locations corresponding to both internal electrode portions 121. The support layer 13 uses, for example, a screen printing method or a heat fusion means using a bonding agent having electrical insulation on the upper surface of the substrate 11 with all the lead portions 122 and the periphery thereof exposed. Is formed. Note that the upper surface of the support layer 13 is also subjected to grafting and anchor treatment with a silane coupling agent or the like as necessary.
ゲル状内部液14は、円盤形のゲル状体であり、支持層13に形成された両孔131内に充填されている。このゲル状内部液14は、例えば、AgCl過飽和の3.3NKClにリン酸緩衝液を加えたもの等に、ゲル化剤とゲル蒸発防止剤を添加して構成されたものであり、例えば、加熱によりペースト状とした上でスクリーン印刷法等により、自由状態においてその上面が支持層13の上面よりも若干突出する状態に充填されて、内部電極部121上に重ねて設けられている。前記ゲル化剤としては、例えば、寒天、ゼラチン、ニカワ、アルギン酸、各種アクリル系吸収性ポリマー等が用いられ、前記ゲル蒸発防止剤としては、例えば、グリセリン、エチレングリコール等が用いられる。 The gel-like internal liquid 14 is a disc-like gel-like body, and is filled in both holes 131 formed in the support layer 13. This gel-like internal liquid 14 is constituted by adding a gelling agent and a gel evaporation inhibitor to, for example, a phosphate buffer solution added to 3.3 NKCl with AgCl supersaturation. In the free state, the upper surface is filled in a state protruding slightly from the upper surface of the support layer 13 by a screen printing method or the like, and is provided on the internal electrode part 121 in an overlapping manner. Examples of the gelling agent include agar, gelatin, glue, alginic acid, various acrylic absorbent polymers, and examples of the gel evaporation inhibitor include glycerin and ethylene glycol.
更に、両孔131のうちの一方の孔131内におけるゲル状内部液14の上方においては、感応部3が、その下面がゲル状内部液14の上面に密着するとともに、ゲル状内部液14が孔131内に密封される状態に、電気絶縁性を有する接着剤を用いて、その周縁部において支持層13の上面に固着されて、pH電極10Pを構成している。 Further, in the upper part of the gel-like internal liquid 14 in one of the holes 131, the sensitive portion 3 has its lower surface in close contact with the upper surface of the gel-like internal liquid 14, and the gel-like internal liquid 14 is A pH electrode 10 </ b> P is configured by adhering to the upper surface of the support layer 13 at the peripheral edge thereof using an electrically insulating adhesive while being sealed in the hole 131.
液絡膜15は、KCl溶液を含浸させた無機焼結多孔体や有機高分子多孔体等からなるものであり、他方の孔131内におけるゲル状内部液14の上方に設けられて、感応部3と同様に、その下面がゲル状内部液14の上面に密着する状態に、その周縁部において支持層13の上面に固着されて、比較電極10Rを構成している。 The liquid junction film 15 is made of an inorganic sintered porous body or an organic polymer porous body impregnated with a KCl solution, and is provided above the gel-like internal liquid 14 in the other hole 131 to provide a sensitive part. 3, the lower surface is adhered to the upper surface of the support layer 13 at the peripheral edge so that the lower surface thereof is in close contact with the upper surface of the gel internal liquid 14, thereby constituting the comparison electrode 10 </ b> R.
上記のように構成されたシート型複合電極10は、その全体厚さが0.5mm程度のものであり、図7に示すように、pH電極10P及び比較電極10Rを上面側に露出し、かつ、リード部122が形成されている基板11の一端縁部を外側方に突出させる状態で、合成樹脂製のケーシング110内に収納されて、チップ状の測定電極ユニット100を構成している。 The sheet-type composite electrode 10 configured as described above has an overall thickness of about 0.5 mm, and as shown in FIG. 7, the pH electrode 10P and the comparison electrode 10R are exposed on the upper surface side, and The chip-shaped measurement electrode unit 100 is configured by being housed in a synthetic resin casing 110 in a state in which one end edge of the substrate 11 on which the lead portion 122 is formed protrudes outward.
チップ状測定電極ユニット100を構成するケーシング110は、試料溶液注入用凹部111を形成する上部枠体112と、その上部枠体112に対する底蓋113と、上部枠体112の一端縁部において揺動開閉自在に取り付けられた試料溶液注入用凹部111に対する上蓋114とからなり、更に、そのケーシング110(本実施形態では上部枠体112の部分)におけるリード部122が突出されている側の端縁からは、後述するpH計本体1000に対する係合用突片115が連設されている。 The casing 110 that constitutes the chip-shaped measurement electrode unit 100 swings at the upper frame 112 that forms the concave portion 111 for sample solution injection, the bottom lid 113 with respect to the upper frame 112, and one edge of the upper frame 112. An upper lid 114 for the sample solution injection recess 111 that can be freely opened and closed, and further, from the edge of the casing 110 (the portion of the upper frame body 112 in the present embodiment) on the side from which the lead portion 122 protrudes. Includes a protrusion 115 for engagement with a pH meter main body 1000 to be described later.
このようなシート型複合電極10を内蔵するチップ状測定電極ユニット100は、上蓋114を開けて、試料溶液注入用凹部111内に試料溶液を1〜数滴程度注入することにより、その底部に位置するpH電極10P及び比較電極10Rを充分に試料溶液に浸した上で、その上蓋114を閉じ、しかる後、図8に示すように、そのチップ状測定電極ユニット100を、カード電卓型に構成されたpH計本体1000の接着部1100へ、リード部122及び係合用突片115を差し込み接続し、試料溶液のpHを測定する。 The chip-shaped measurement electrode unit 100 incorporating such a sheet-type composite electrode 10 is located at the bottom by opening the upper lid 114 and injecting about one to several drops of the sample solution into the sample solution injection recess 111. After the pH electrode 10P and the comparison electrode 10R to be sufficiently immersed in the sample solution, the upper lid 114 is closed, and then the chip-like measurement electrode unit 100 is configured in a card calculator type as shown in FIG. The lead portion 122 and the engaging protrusion 115 are inserted and connected to the adhesive portion 1100 of the pH meter main body 1000, and the pH of the sample solution is measured.
このように構成した本実施形態に係るシート型複合電極10によれば、電極10をシート型に構成することにより、電極10の小型化が可能となり、また、シート型複合電極10の上面に露出したpH電極10P及び比較電極10Rの上に試料溶液を1〜数滴垂らせばpH測定を行うことができるので、試料溶液が少量である場合も良好に測定を行うことができる。 According to the sheet-type composite electrode 10 according to the present embodiment configured as described above, the electrode 10 can be reduced in size by configuring the electrode 10 to be a sheet-type, and exposed to the upper surface of the sheet-type composite electrode 10. Since the pH measurement can be performed by dropping one to several drops of the sample solution on the pH electrode 10P and the comparison electrode 10R, the measurement can be performed satisfactorily even when the amount of the sample solution is small.
<その他の変形実施形態>
なお、本発明は前記実施形態に限られるものではない。
<Other modified embodiments>
The present invention is not limited to the above embodiment.
例えば、第1実施形態において、感応部3の形成箇所は特に限定されず、図9に示すように、支持管2の先端開口部であってもよく、また、支持管2の形状も特に限定されず、例えば、円筒状であってもよい。更に、第1実施形態においても、感応部3は取り換え可能に構成してあってもよい。 For example, in the first embodiment, the position where the sensitive portion 3 is formed is not particularly limited, and may be the tip opening of the support tube 2 as shown in FIG. 9, and the shape of the support tube 2 is also particularly limited. For example, it may be cylindrical. Furthermore, also in the first embodiment, the sensitive unit 3 may be configured to be replaceable.
第2実施形態において、膜固定部24は支持管2の先端部23と螺合するように構成されているが、膜固定部24が支持管2の先端部23に嵌合するものであって、膜固定部24を支持管2の先端部23に嵌め込むことにより、膜固定部24が支持管2の先端部23に固定されるものであってもよい。 In the second embodiment, the membrane fixing portion 24 is configured to be screwed with the distal end portion 23 of the support tube 2, but the membrane fixing portion 24 is fitted to the distal end portion 23 of the support tube 2. Alternatively, the membrane fixing portion 24 may be fixed to the tip portion 23 of the support tube 2 by fitting the membrane fixing portion 24 into the tip portion 23 of the support tube 2.
また、前記の各実施形態において、二酸化チタンに代えて、二酸化ジルコニウム、酸化アルミニウム、二酸化ケイ素を用いてもよい。 In each of the above embodiments, zirconium dioxide, aluminum oxide, or silicon dioxide may be used instead of titanium dioxide.
その他、前述した実施形態や変形実施形態の一部又は全部を適宜組み合わせてもよく、本発明は、その趣旨を逸脱しない範囲で種々の変形が可能である。 In addition, a part or all of the above-described embodiments and modified embodiments may be appropriately combined, and the present invention can be variously modified without departing from the spirit thereof.
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。 The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.
SUS304基板に対し、ゾルゲル・ディップコーティング法を用いて両面にTiO2をコートした。コーティング溶液としては、[(CH3)2CHO]4Ti、CH3O(CH2)2OH、H2O、及び、HNO3からなる混合溶液を用いた。コーティング回数は1回、焼成は400℃、500℃又は600℃で10分+24時間行った。TiO2をコートしたSUS304基板を塩化ビニル製のセルに取り付け、pH電極を作製した。そして、作製したpH電極の電位測定を、pH7→pH4→pH9の順で3回行ない、3回目の測定開始から3分経過後の値を用いて、pH4−9間のpH感度と応答時間を求めた。この際、比較電極としては堀場製作所製(#2565)を使用した。得られた結果は図10及び図11に示した。なお、サンプル名は[基板名 焼成温度 − コーティング回数]で示した。 A SUS304 substrate was coated with TiO 2 on both sides using a sol-gel dip coating method. As the coating solution, a mixed solution composed of [(CH 3 ) 2 CHO] 4 Ti, CH 3 O (CH 2 ) 2 OH, H 2 O, and HNO 3 was used. The number of coatings was 1, and baking was performed at 400 ° C., 500 ° C. or 600 ° C. for 10 minutes + 24 hours. A SUS304 substrate coated with TiO 2 was attached to a cell made of vinyl chloride to produce a pH electrode. Then, the potential measurement of the prepared pH electrode is performed three times in the order of pH 7 → pH 4 → pH 9, and the pH sensitivity and response time between pH 4-9 are determined using the values after 3 minutes from the start of the third measurement. Asked. At this time, Horiba Seisakusho (# 2565) was used as a reference electrode. The obtained results are shown in FIGS. The sample name is indicated by [substrate name baking temperature−number of coatings].
図10には、TiO2をコートしたSUS304電極の焼成温度に伴うpH感度の変化を示した。TiO2をコートしたSUS304電極は、焼成温度によらず、いずれも80%以上のpH感度を示した。なかでも、500℃で焼成を行ったSUS304電極(SUS500−1)が最も高いpH感度(96.8%)を示した。市販のガラス電極の感度は97.5%以上であるため、SUS500−1電極はガラス電極とほぼ同程度のpH応答をすることが分かった。 FIG. 10 shows the change in pH sensitivity with the firing temperature of the SUS304 electrode coated with TiO 2 . The SUS304 electrode coated with TiO 2 showed a pH sensitivity of 80% or more regardless of the firing temperature. Among them, the SUS304 electrode (SUS500-1) fired at 500 ° C. showed the highest pH sensitivity (96.8%). Since the sensitivity of a commercially available glass electrode is 97.5% or more, it has been found that the SUS500-1 electrode has a pH response substantially the same as that of the glass electrode.
図11には、TiO2をコートしたSUS304電極の焼成温度に伴う応答時間の変化を示した。ガラス電極の応答時間は11秒であり、参考のためグラフ中に破線で示した。焼成温度を変えたSUS304電極間で、応答時間に差は見られず、いずれもガラス電極よりも応答時間が短いという結果を得ることができた。従って、TiO2をコートしたSUS304基板を電極の感応部として用いることにより応答速度の向上を図れることが判明した。 FIG. 11 shows the change in response time with the firing temperature of the SUS304 electrode coated with TiO 2 . The response time of the glass electrode is 11 seconds, and is indicated by a broken line in the graph for reference. There was no difference in the response time between the SUS304 electrodes with different firing temperatures, and the results were that the response time was shorter than that of the glass electrode. Accordingly, it has been found that the response speed can be improved by using a SUS304 substrate coated with TiO 2 as the sensitive part of the electrode.
これらの結果から、TiO2をコートしたSUS304基板を感応部とした電極は、ガラス電極に近い感度を示し、応答速度も向上することが明らかとなった。 From these results, it has been clarified that an electrode using a SUS304 substrate coated with TiO 2 as a sensitive part exhibits sensitivity close to that of a glass electrode and improves the response speed.
本発明によれば、応答精度が向上するとともに、製造が容易でコストの低減が可能となり、また、感応部を破損しにくいものとすることができる上に、感応部にセルフクリーニング機能を発現させたイオン選択性電極を提供することが可能となる。 According to the present invention, the response accuracy is improved, the manufacturing is easy and the cost can be reduced, the sensitive part can be made less likely to be damaged, and the self-cleaning function is expressed in the sensitive part. It is possible to provide an ion selective electrode.
1…pH電極
2…支持管
3…感応部
31…支持板
32…二酸化チタン膜
4…内部電極
5…内部液
6…リード線
DESCRIPTION OF SYMBOLS 1 ... pH electrode 2 ... Support tube 3 ... Sensing part 31 ... Support plate 32 ... Titanium dioxide film 4 ... Internal electrode 5 ... Internal liquid 6 ... Lead wire
Claims (5)
前記感応部が、金属からなる電子伝導性支持体と、前記電子伝導性支持体の前記試料溶液と接する面側の表面に形成された金属酸化物を含有する多孔質膜とを備えたことを特徴とするイオン選択性電極。 An ion selective electrode comprising an internal electrode, an internal liquid in contact with the internal electrode, and a sensitive part having a surface in contact with the internal liquid and a surface in contact with the sample solution,
Said sensing portion is provided with an electron conductive support made of a metal, and a porous film containing the metal oxide formed in said surface of the sample solution in contact with the surface side of the electronic conductive support Characteristic ion-selective electrode.
前記多孔質膜が前記電子伝導性支持体をコーティング溶液でコーティングして焼成する方法により形成されることを特徴とするイオン選択性電極の製造方法。 Sensitive part having a surface in contact with the surface and the sample solution in contact with the internal solution, the electron conductive support and, the electron conductive support said metal oxide formed on the surface of the side in contact with the sample solution comprising a metal A method for producing an ion-selective electrode comprising a porous membrane containing
The method for producing an ion-selective electrode, wherein the porous membrane is formed by a method in which the electron conductive support is coated with a coating solution and baked.
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DE2820475A1 (en) * | 1978-05-10 | 1979-11-15 | Fresenius Chem Pharm Ind | ION-SELECTIVE ELECTRODE |
JPS57203946A (en) * | 1981-06-11 | 1982-12-14 | Olympus Optical Co Ltd | Ion selective electrode |
JPS58172541A (en) * | 1982-04-02 | 1983-10-11 | Terumo Corp | Ion electrode substrate and ion electrode |
JPS60195445A (en) * | 1984-03-19 | 1985-10-03 | Horiba Ltd | Ph measuring electrode |
JPS63193053A (en) * | 1987-02-06 | 1988-08-10 | Toshiba Corp | Ph measuring apparatus for high temperature |
JPS6435356A (en) * | 1987-07-31 | 1989-02-06 | Shimadzu Corp | Ion sensor and its production |
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JP2999854B2 (en) * | 1991-05-18 | 2000-01-17 | 株式会社堀場製作所 | Method for producing metal thin film for hydrogen sensor, gas sensor or pH response |
DE10018750C2 (en) * | 1999-04-23 | 2003-03-27 | Kurt Schwabe Inst Fuer Mess Un | Fixed contact ion-selective glass electrode and process for its production |
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