JP3851389B2

JP3851389B2 - Liquid junction member for comparison electrode and comparison electrode using the same

Info

Publication number: JP3851389B2
Application number: JP27718096A
Authority: JP
Inventors: 恵和岩本; 伸二武市; 浩美大川
Original assignee: Horiba Ltd
Current assignee: Horiba Ltd
Priority date: 1996-09-28
Filing date: 1996-09-28
Publication date: 2006-11-29
Anticipated expiration: 2016-09-28
Also published as: JPH10104193A

Description

【０００１】
【発明の属する技術分野】
本発明はｐＨ測定用等に用いられる比較電極用液絡部材およびこれを用いた比較電極に関する。
【０００２】
【発明が解決しようとする課題】
従来、例えば図５に示されるようなｐＨ計等の比較電極ａ用の液絡部材ｂの素材として、多孔質セラミックが用いられることが多い。しかし、このような液絡部材ｂでは、内部液（Ａｇ／ＡｇＣｌ）ｃに溶解したＡｇ⁺やＡｇＣｌ₂ ^-の錯体がセラミックとサンプル接触界面にてＡｇＣｌを析出し詰まり易いという難点があった。これにより、内部液ｃの洩出が緩慢になり液間電位差が発生しやすくなり、その液間電位差の発生によりイオン濃度測定値に誤差が生じていた。なお、図５中、符号ｄは比較電極内極である。
【０００３】
また、その液絡部材ｂは、サンプルを吸収しやすく、液置換時においても液間電位差が発生しやすく、サンプル履歴により、電位変動が大になることもあった。
【０００４】
しかも、液絡部材ｂを構成するセラミック自体の品質特性にバラツキがあることが多く、その場合には、内部液ｃの洩出量（流速）にバラツキが生じ、これを低減化するのは一般に困難であった。
【０００５】
本発明はこのような実情に鑑みてなされ、比較電極の電位安定が速く、液間電位差の発生が少なく、長期にわたり、液詰まりが生じにくい液絡部材およびこれを用いた比較電極を提供することを目的としている。
【０００６】
【課題を解決するための手段】
本発明は上述の課題を解決するための手段を以下のように構成している。
すなわち、本発明の比較電極用液絡部材は、ＺｒＯ ₂ が主な成分であるセラミックまたはガラスを素材とし、内部液側と試料液側とにわたって貫通する直線的な微細径の貫通孔を有し、前記貫通孔の内面に撥水処理を施したことを特徴としている（請求項１）。
【０００７】
内部液側と試料液側とにわたって貫通する直線的な微細径の貫通孔が設けられていることにより、内部液の試料液側への洩出時の流速が速くなるとともに、サンプル接液界面における拡散電位の安定性が良好となり、液間電位の発生が少なくなる。また、液詰まりも少なくなる。
その上、貫通孔の内面に撥水処理が施されているので、内部液の洩出時の流速がより一層速くなり、また、液詰まりもさらに少なくなる。
【０００８】
また、本発明の比較電極用液絡部材は、ＺｒＯ ₂ が主な成分であるセラミックまたはガラスを素材とし、内部液側と試料液側とにわたって貫通する直線的な微細径の貫通孔を有し、前記貫通孔の内面に撥水処理を施してあり、また、前記貫通孔は単一部材に複数形成されたものでもよい（請求項２）。
【０００９】
【００１０】
そして、前記貫通孔の長さを調整することにより、内部液の試料液側への洩出時の抵抗を調整するようにしてもよい（請求項３）。
貫通孔の長さを調整することにより、内部液の洩出時の抵抗を調整することができるので、洩出時間の調整が可能となり、液詰まりが生じにくいようにすることが容易となる。
【００１１】
さらに、本発明の比較電極は、請求項１〜３のいずれかに記載の液絡部材を備えてなることを特徴としている（請求項４）。
【００１２】
【発明の実施の形態】
以下に本発明の比較電極用液絡部材の実施形態につき図面を参照しつつ説明する。
図１は比較電極１の断面図で、２は鉛ガラスよりなる支持管、３はその支持管２の先端部に嵌装された液絡部材でＺｒＯ₂ を主な成分とするセラミックまたはガラスキャピラリー等よりなり、１０〜１００μｍ程度のストレートな単孔状の貫通孔３１を有している。４はＫＣｌよりなる内部液、５はＡｇ／ＡｇＣｌよりなる内部電極である。
【００１３】
上述の液絡部材３の拡大断面は図２に示され、その貫通孔３１は内部液４に対する接液面側３２と試料液（図示省略）に対する接液面側３３とにわたって貫通して開設され、その内壁面には、シリコンやフッ素化合物等の撥水剤３１１がコーティング（１０・厚程度）されており、これにより、従来の多孔質セラミック電極やスリーブ形電極に比べて内部液４の洩出時の流速が速くなるため、サンプル接液界面における拡散電位の安定性が良好となり液間電位差の発生が少なくなる。
【００１４】
また、上述のような撥水剤３１１のコーティングにより、直接内部液４が接する貫通孔３１の内壁面の品質特性が均一化されるため、内部液４の洩出流速がバラツキなく安定化され、信頼性が向上すると共に、液詰まりが発生しにくくなり、長期にわたり安定した性能特性を維持することができるようになる。なお、その貫通孔３１は複数設けられてもよいのはいうまでもない（図４参照）。
【００１５】
ＺｒＯ₂ セラミックは熱膨張率が鉛ガラスとほぼ等しく、バーナー加工によってその液絡部材３を支持管２に容易に熱融着させることができる。この場合、液絡部３が支持管２と一体で成形されているのではなく、別体として成形し、後に一体化させるので、液絡部３を適切な材質で構成することが容易となり、また、内部液が洩出する際の流通の調整も行いやすくなる。なお、上述のような貫通孔３１を有するＺｒＯ₂ セラミックとしては、例えば、パイロットプレシジョン社製のものがある。
【００１６】
ちなみに、ＺｒＯ₂ セラミックの貫通孔（直径２０μｍ、長さ２〜３ｍｍ）３１に撥水処理を施した液絡部材３を用いた本発明の比較電極１と従来の多孔質セラミックを用いた比較電極の液間電位差を比較した結果を表１に示す。
【００１７】
【表１】

【００１８】
この場合、比較電極内極としてＡｇ／ＡｇＣｌ、内部液として３．３ｍｏｌ／ｌＫＣｌ溶液を用いており、また、Ｂ−７，Ｂ−４，Ｂ−９はそれぞれ２５℃において９．１８ｐＨ、４．０１ｐＨ、６．８６ｐＨのバッファ標準液を示す。表１より、本発明の場合ｐＨ１〜ｐＨ１３の範囲内において液間電位差のずれが２ｍＶ以内で安定であり、特に、ＮａＯＨとＨＣｌ間における液間電位差の変動が従来の１／３以下となっている。
【００１９】
また、上述の本発明の液絡部材３を用いた比較電極１における液間電位差の応答性については、図３に示されるように、Ｂ４→Ｂ９→ＮａＯＨ→Ｂ２→ＨＣｌ→Ｂ７の順に順次測定対象液を置換した場合、酸、アルカリ置換時にも３０秒以内に液間電位差が安定することが確認されている。なお、この場合、比較電極内極Ａｇ／ＡｇＣｌ、内部液として３．３３ｍｏｌ／ｌＫＣｌ溶液を用いている。
【００２０】
【００２１】
【発明の効果】
以上説明したように、請求項１に記載の発明によれば、内部液側と試料液側とにわたり貫通する微細径の貫通孔を有するので、内部液の洩出流速が速く、比較電極の電位安定性が良好となり、液間電位差の発生が少なくなり、かつ、液詰まりが生じにくく、長期にわたり高い信頼性を維持することが可能となる。
【００２２】
また、請求項１に記載の発明によれば、貫通孔の内面に撥水処理を施しているので、内部液の洩出流速がより一層速くなり、また、液詰まりもさらに少なくなる。
【００２３】
そして、請求項３に記載の発明によれば、貫通孔の長さを調整することにより、内部液の試料液側への洩出時の抵抗を調整するようにしたので、洩出時間の調整が可能となり、液詰まりを生じさせないようにすることができる。
【図面の簡単な説明】
【図１】本発明の比較電極用液絡部材の一実施形態を示す断面図である。
【図２】前記液絡部材の縦断面図である。
【図３】前記液絡部材を用いた比較電極における液間電位差応答例を示すグラフである。
【図４】本発明の比較電極用液絡部材の他の実施形態における横断面図である。
【図５】従来の比較電極の断面図である。
【符号の説明】
３…液絡部材、３１…貫通孔。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid junction member for a comparative electrode used for pH measurement and the like, and a comparative electrode using the same.
[0002]
[Problems to be solved by the invention]
Conventionally, for example, a porous ceramic is often used as a material for a liquid junction member b for a comparative electrode a such as a pH meter as shown in FIG. However, in such a liquid junction member b, internal solution (Ag / AgCl) Ag was dissolved in c ⁺ and AgCl ₂ ^- had the complex to precipitate AgCl in ceramic and the sample contacting surface drawback easily clogged. As a result, the leakage of the internal liquid c becomes slow and an inter-liquid potential difference is easily generated, and an error occurs in the ion concentration measurement value due to the generation of the inter-liquid potential difference. In FIG. 5, the symbol d is the reference electrode inner pole.
[0003]
In addition, the liquid junction member b easily absorbs the sample, easily causes an inter-liquid potential difference even when the liquid is replaced, and the potential fluctuation may become large due to the sample history.
[0004]
In addition, there are many variations in the quality characteristics of the ceramic itself constituting the liquid junction member b. In this case, the amount of leakage (flow velocity) of the internal liquid c varies, and this is generally reduced. It was difficult.
[0005]
The present invention has been made in view of such a situation, and provides a liquid junction member in which the potential of the reference electrode is fast, the potential difference between liquids is small, and liquid clogging does not easily occur for a long time, and a reference electrode using the same. It is an object.
[0006]
[Means for Solving the Problems]
In the present invention, means for solving the above-described problems are configured as follows.
That is, the liquid junction member for a comparative electrode of the present invention is ZrO ₂ Is a material of ceramic or glass is the main component, has a linear fine diameters of the through-hole penetrating across the internal liquid side and the sample liquid side, and this was subjected to a water repellent treatment on the inner surface of the through hole It is characterized (claim 1).
[0007]
By providing a linear fine-diameter through-hole penetrating the internal liquid side and the sample liquid side, the flow rate when the internal liquid leaks to the sample liquid side is increased, and at the sample wetted interface The stability of the diffusion potential is improved, and the generation of the liquid junction potential is reduced. Moreover, liquid clogging is reduced.
Moreover, since the water-repellent treatment is applied to the inner surface of the through hole, the flow rate at the time of demonstration of the internal fluid becomes more one layer faster, The liquid clogging becomes even less.
[0008]
Moreover, the liquid junction member for a reference electrode of the present invention is ZrO _2. Is made of ceramic or glass, which is the main component, has a through hole with a linear fine diameter that penetrates through the inner liquid side and the sample liquid side, and has been subjected to water repellent treatment on the inner surface of the through hole, A plurality of the through holes may be formed in a single member (claim 2).
[0009]
[0010]
Then, the by adjusting the length of the through-holes may be adjusted to the resistance at the time of demonstration of the sample liquid side of the internal solution (請Motomeko 3).
By adjusting the length of the through hole, the resistance at the time of leakage of the internal liquid can be adjusted, so that the leakage time can be adjusted, and it becomes easy to prevent liquid clogging.
[0011]
Furthermore, reference electrode of the invention is characterized in that it comprises a liquid junction member according to claim 1 (請Motomeko 4).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a liquid junction member for a comparative electrode according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a comparative electrode 1, 2 is a support tube made of lead glass, 3 is a liquid junction member fitted at the tip of the support tube 2, and is a ceramic or glass capillary containing ZrO ₂ as a main component. Etc., and has a straight single-hole through-hole 31 of about 10 to 100 μm. 4 is an internal solution made of KCl, and 5 is an internal electrode made of Ag / AgCl.
[0013]
An enlarged cross section of the liquid junction member 3 is shown in FIG. 2, and the through hole 31 is opened through the liquid contact surface side 32 for the internal liquid 4 and the liquid contact surface side 33 for the sample liquid (not shown). The inner wall surface is coated with a water repellent 311 such as silicon or a fluorine compound (about 10 · thickness), so that the internal liquid 4 leaks as compared with a conventional porous ceramic electrode or sleeve type electrode. Since the flow rate at the time of discharge becomes faster, the stability of the diffusion potential at the sample-wetted interface is improved, and the occurrence of an inter-liquid potential difference is reduced.
[0014]
Moreover, since the quality characteristics of the inner wall surface of the through-hole 31 with which the internal liquid 4 is in direct contact are made uniform by the coating of the water repellent 311 as described above, the leakage flow rate of the internal liquid 4 is stabilized without variation, Reliability is improved, liquid clogging is less likely to occur, and stable performance characteristics can be maintained over a long period of time. Needless to say, a plurality of through holes 31 may be provided (see FIG. 4).
[0015]
ZrO ₂ ceramic has a thermal expansion coefficient substantially equal to that of lead glass, and the liquid junction member 3 can be easily heat-sealed to the support tube 2 by burner processing. In this case, the liquid junction 3 is not molded integrally with the support tube 2, but is formed as a separate body and later integrated, so that it becomes easy to configure the liquid junction 3 with an appropriate material, Moreover, it becomes easy to adjust the flow when the internal liquid leaks. As the ZrO ₂ ceramic having through-holes 31 as described above, for example, those of the pilot Precision Corporation.
[0016]
Incidentally, the comparative electrode 1 of the present invention using the liquid junction member 3 in which the water-repellent treatment is performed on the ZrO ₂ ceramic through hole (diameter 20 μm, length 2 to 3 mm) 31 and the comparative electrode using the conventional porous ceramic Table 1 shows the result of comparison of the potential difference between the two liquids.
[0017]
[Table 1]

[0018]
In this case, Ag / AgCl is used as the inner electrode of the reference electrode, and 3.3 mol / l KCl solution is used as the inner solution, and B-7, B-4, and B-9 are 9.18 pH and 4. A buffer standard solution of 01 pH and 6.86 pH is shown. From Table 1, in the case of the present invention, the deviation of the liquid potential difference is stable within 2 mV within the range of pH 1 to pH 13, and in particular, the fluctuation of the liquid potential difference between NaOH and HCl is 1/3 or less of the conventional. Yes.
[0019]
Further, as shown in FIG. 3, responsiveness of the liquid-potential difference in the comparison electrode 1 using the liquid junction member 3 of the present invention described above is sequentially measured in the order of B4 → B9 → NaOH → B2 → HCl → B7. When the target liquid is replaced, it has been confirmed that the liquid potential difference is stabilized within 30 seconds even when the acid or alkali is replaced. In this case, a reference electrode inner electrode Ag / AgCl and a 3.33 mol / l KCl solution are used as the inner solution.
[0020]
[0021]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the fine-diameter through-hole penetrates between the internal liquid side and the sample liquid side, the leakage flow rate of the internal liquid is high, and the potential of the reference electrode is high. Stability is improved, the potential difference between the liquids is reduced, liquid clogging hardly occurs, and high reliability can be maintained over a long period of time.
[0022]
Further, according to the first aspect of the present invention, the water repellent treatment is applied to the inner surface of the through hole, so that the leakage speed of the internal liquid is further increased and the liquid clogging is further reduced.
[0023]
According to the invention described in claim 3, since the resistance at the time of leakage of the internal liquid to the sample liquid side is adjusted by adjusting the length of the through hole, the leakage time is adjusted. It is possible to prevent clogging.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a liquid junction member for a comparative electrode of the present invention.
FIG. 2 is a longitudinal sectional view of the liquid junction member.
FIG. 3 is a graph showing an example of an inter-liquid potential difference response in a reference electrode using the liquid junction member.
FIG. 4 is a cross-sectional view of another embodiment of a liquid junction member for a reference electrode according to the present invention.
FIG. 5 is a cross-sectional view of a conventional comparison electrode.
[Explanation of symbols]
3 ... Liquid junction member, 31 ... Through-hole.

Claims

ZrO ₂₂ It is made of ceramic or glass, which is the main component, has a through hole with a linear fine diameter that penetrates through the internal liquid side and the sample liquid side, and water repellent treatment is applied to the inner surface of the through hole. A liquid junction member for a reference electrode.

ZrO ₂₂ Is made of ceramic or glass, which is the main component, has a through hole with a linear fine diameter that penetrates through the inner liquid side and the sample liquid side, and has been subjected to water repellent treatment on the inner surface of the through hole, A liquid junction member for a comparative electrode, wherein a plurality of the through holes are formed in a single member.

The liquid junction member for a comparative electrode according to claim 1 or 2, wherein the resistance at the time of leakage of the internal liquid to the sample liquid side is adjusted by adjusting the length of the through hole.

A comparison electrode comprising the liquid junction member for comparison electrode according to claim 1.