JP2004347366A

JP2004347366A - Calibrating method of residual chlorine concentration measuring instrument and residual chlorine concentration measuring instrument

Info

Publication number: JP2004347366A
Application number: JP2003142274A
Authority: JP
Inventors: Satoyuki Ikegaya; 智行池ヶ谷; Manabu Negishi; 学根岸
Original assignee: DKK TOA Corp
Current assignee: DKK TOA Corp
Priority date: 2003-05-20
Filing date: 2003-05-20
Publication date: 2004-12-09
Anticipated expiration: 2023-05-20
Also published as: JP4322555B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibrating method of a residual chlorine concentration measuring instrument and a residual chlorine concentration measuring instrument, for simply calibrating the output of an exposed-type residual chlorine electrode, in which a working electrode and a counter electrode make direct contact with test water, without using a standard solution containing residual chlorine or other analysis methods. <P>SOLUTION: This residual chlorine concentration measuring instrument comprises a detection electrode 10 equipped with the working electrode 13 and the counter electrode 14, and a current detection means 25 for detecting a current flowing across the working electrode 13 and the counter electrode 14. According to this calibrating method, the working electrode 13 and the counter electrode 14 are respectively, at least partly, brought into contact with the test water to detect residual chlorine reduction current flowing across the working electrode 13 and the counter electrode 14, thereby detecting the concentration of residual chlorine in the test water. Residual chlorine detection sensitivity of the detection electrode 10 with respect to the test water is found based on a detected oxygen reduction current flowing across the working electrode 13 and the counter electrode 14 when applying an oxygen reduction voltage across the working electrode 13 and the counter electrode 14 with respect to the test water saturated with dissolved oxygen. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、一般には、作用極と対極とを備えた検出電極を用いて残留塩素還元電流を検出し、試料液（検水）中の残留塩素の濃度を検出する、所謂、ポーラログラフ法を利用した残留塩素濃度測定装置の校正方法、及び該校正方法が適用される残留塩素濃度測定装置に関するものであり、特に、検出電極として隔膜を有しておらず作用極と対極とが直接検水に接触する露出型残留塩素電極を備えた残留塩素濃度測定装置の校正方法、及び該校正方法が適用される残留塩素濃度測定装置に関するものである。
【０００２】
【従来の技術】
従来、検水中の残留塩素濃度を検出するために、所謂、ポーラログラフ法を用いる検出電極、即ち、残留塩素電極にて、残留塩素の還元電流を測定することが行われている。
【０００３】
斯かる残留塩素電極を備えた残留塩素濃度測定装置は、例えばプール水、水道水（上水）中の残留塩素濃度測定に利用される。又、例えばカット野菜、果実などの食料品の洗浄、殺菌のために、次亜塩素酸ナトリウムを水道水又は地下水で希釈した塩素濃度の比較的濃い塩素殺菌液（約２００ｍｇ／Ｌ）が用いられるが、この洗浄、殺菌の前後においてシンクなどに入った洗浄、殺菌液の残留塩素を測定するために上記残留塩素濃度測定装置が利用される。
【０００４】
残留塩素電極としては、（ａ）作用極及び対極を隔膜によって検水から隔離して、電極内空間に電解液を満たしてこれに作用極と対極とを浸漬する隔膜型残留塩素電極と、（ｂ）作用極及び対極のそれぞれの少なくとも一部が検水に接する露出型残留塩素電極がある。
【０００５】
隔膜型残留塩素電極は、隔膜を透過したガスが電解液のｐＨを変化させるような場合には誤差を生じるが、基本的には検水のｐＨ、ＥＣ（電気伝導率）等の影響を受けないという利点を有している。しかし、隔膜型残留塩素電極には、次のような問題がある。（ｉ）定期的に電解液、隔膜の交換が必要であると共に、その際に電極内に気泡を入れぬよう熟練が必要であり、保守が煩雑である。（ｉｉ）隔膜を透過した残留塩素を測定するため、応答性が悪い。（ｉｉｉ）電極出力が安定するまで、半日程度放置する必要があり、保守後の応答性が悪い。（ｉｖ）物理的な汚れが隔膜に付着すると、ガスの透過量が落ちることにより誤差を生じ、しかも上記のように隔膜の交換は煩雑であり保守性が悪い。（ｖ）電解液を検水に流出させぬよう、隔膜部にシール構造が必要であり、構造が複雑である。
【０００６】
これに対して、露出型残留塩素電極は、次のような利点を有している。（ｉ）作用極と対極とが剥き出しになっているため洗浄が容易であり、保守が簡単である。（ｉｉ）残留塩素が直接作用極に到達するため、応答性が良い。（ｉｉｉ）保守（洗浄）後であっても直ぐに測定でき、保守後の応答性が良い。（ｉｖ）作用極又は対極に汚れが付着すると電気抵抗の変化のために誤差を生じることがあるが、上記のように洗浄が容易であり保守性が良い。（ｖ）実質的に作用極と対極だけで構成できるため、構造が簡単である。
【０００７】
このように、露出型残留塩素電極は、保守性、応答性、構造の簡易性等の点で、隔膜型電極に対して優れている。
【０００８】
ところで、通常、残留塩素電極は、使用することにより作用極及び／又は対極の消耗などによって、電極感度が変化する。そのため、従来、一般には、所定の濃度の残留塩素を含有する標準液を調製し、これに対する電極出力を測定することで電極の感度変化を求めて校正を行っている。
【０００９】
しかし、残留塩素は化学的に不安定な物質であり、常に一定濃度の標準液を調製することは困難である。従って、正確に校正を行うためには、調製した標準液の残留塩素濃度を決定する必要があるが、そのためには比色法などの他の分析法を用いなければならない。加えて、残留塩素は、濃度の経時変化が大きいため、標準液をまとめて調製して保管することが困難であり、校正の都度調製しなければならず、校正操作は極めて煩雑である。
【００１０】
特許文献１は、校正を容易とした残留塩素計を提案している。即ち、特許文献１は、所定の濃度の残留塩素を含む校正標準液を用いる代わりに、大気中の酸素濃度に基づいてスパン校正を行うことを開示している。しかし、斯かる先行技術は、隔膜型残留塩素電極に関するものであり、対極や電解液の消耗による感度変化を校正することを開示しているが、検水の水質（ｐＨ、ＥＣ、汚れ等）の影響による感度変化を校正することについては何ら示していない。
【００１１】
【特許文献１】
特開２００２−１１６１８２号公報
【００１２】
【発明が解決しようとする課題】
上述のように、露出型残留塩素電極は、隔膜型残留塩素電極と比較して、保守性、応答性、構造の簡易性の点で多くの利点を有しているが、以下のような問題点を有する。
【００１３】
露出型残留塩素電極は、隔膜を有しておらず、作用極と対極とが直接検水に接触するため、検水の水質（ｐＨ、ＥＣ、汚れ等）が変化すると、その影響が電極出力に現れる。
【００１４】
このため、作用極及び／又は対極の消耗、汚れの付着等によって電極感度が変化していなくても、検水の水質の影響で電極感度は変化する。
【００１５】
又、露出型残留塩素電極では、従来一般に行われているように残留塩素を含有する標準液を用いて感度校正を行うと、残留塩素の化学的な不安定さに起因する上述のような煩雑さ、正確性等における問題に加えて、検水の水質が標準液と異なっている場合に、斯かる標準液にて感度校正を行ったとしても検水の水質の影響により測定値に誤差を生じるという問題がある。
【００１６】
この問題に対処するには、検水と同じ水質条件の正確な標準液を調製することが考えられるが、このような標準液を調製することは極めて困難であり、現実的でない。
【００１７】
そこで、先ず、検水の残留塩素濃度を他の分析方法により測定して、この濃度に電極出力を合わせ込むことで検水の水質の影響をキャンセルし、その後の残留塩素濃度を電極の出力によって測定することが行われる。
【００１８】
しかし、このような方法によれば、正確な校正が可能ではあるが、操作が煩雑であるばかりでなく、校正に多大な時間を要する。そのため、様々な検水に即時対応可能であり、更には携帯性の良い簡易な装置を実現する上では問題である。
【００１９】
尚、上記特許文献１に開示される大気中の酸素濃度に基づいて電極感度をスパン校正する方法は、電極内に満たされた電解液で作用極と対極とが電気的に導通している隔膜型電極に対してのみ適用できるものであり、又、以上のような露出型残留塩素電極について固有の問題点を解決することはできない。
【００２０】
従って、本発明の目的は、作用極と対極とが直接検水に接触する露出型残留塩素電極の出力を、校正時に残留塩素を含有する標準液或いは他の分析方法を用いることなく、簡易に校正することのできる残留塩素濃度測定装置の校正方法及び残留塩素濃度測定装置を提供することである。
【００２１】
本発明の他の目的は、作用極と対極とが直接検水に接触する露出型残留塩素電極の感度の、検水の水質の影響による変化を簡易に校正することができると共に、作用極及び／又は対極の消耗、汚れの付着等による変動をも簡易に校正することのできる残留塩素濃度測定装置の校正方法及び残留塩素濃度測定装置を提供することである。
【００２２】
【課題を解決するための手段】
上記目的は本発明に係る残留塩素濃度測定装置の校正方法及び残留塩素濃度測定装置にて達成される。要約すれば、第１の本発明は、作用極及び対極を具備する検出電極と、前記作用極と前記対極との間に流れる電流を検出する電流検出手段と、を有し、前記作用極及び前記対極のそれぞれの少なくとも一部を検水に接触させて、前記作用極と前記対極との間の残留塩素還元電流を検出して検水中の残留塩素濃度を検出する残留塩素濃度測定装置の校正方法において、溶存酸素を飽和させた検水に対する、前記作用極と前記対極との間に酸素還元電圧を印加した際の前記作用極と前記対極との間の酸素還元電流を検出することに基づいて、検水に対する前記検出電極の残留塩素検出感度を求めることを特徴とする残留塩素濃度測定装置の校正方法である。
【００２３】
第１の本発明の好ましい一実施態様によると、残留塩素濃度測定装置の校正方法は、（ａ）予め求められた前記検出電極の残留塩素検出感度と溶存酸素検出感度との相関と、前記検出電極の当初の残留塩素検出感度と、に基づいて前記検出電極の当初の溶存酸素検出感度を求め；（ｂ）前記作用極と前記対極との間に酸素還元電圧を印加し、溶存酸素を飽和させた検水に対する前記作用極と前記対極との間の酸素還元電流を検出すると共に、検水の温度を検出し、飽和溶存酸素濃度と液温との関係から検水中の溶存酸素濃度を求めて検水に対する前記検出電極の溶存酸素検出感度を求め；（ｃ）前記検出電極の当初の溶存酸素検出感度と、検水に対する前記検出電極の溶存酸素検出感度と、の相関を求めて、該相関に基づいて前記検出電極の当初の残留塩素検出感度から検水に対する前記検出電極の残留塩素検出感度を求める；各段階を含む。
【００２４】
第１の本発明の一実施態様によると、残留塩素濃度測定装置の校正方法は更に、（ｉ）前記検出電極の残留塩素検出感度と溶存酸素検出感度との相関を示す情報、（ｉｉ）前記飽和溶存酸素濃度と液温との関係を示す情報、及び（ｉｉｉ）前記作用極と前記対極との間に残留塩素還元電圧を印加し、所定の濃度の残留塩素を含有する標準液に対する前記作用極と前記対極との間の残留塩素還元電流を検出して求めた前記検出電極の前記当初の残留塩素検出感度を示す情報を、前記残留塩素濃度測定装置が備える記憶手段に記憶させる段階を含む。
【００２５】
又、第１の本発明の一実施態様によると、残留塩素濃度測定装置の校正方法は更に、求められた前記検水に対する前記検出電極の残留塩素検出感度を示す情報を前記残留塩素濃度測定装置が備える記憶手段に記憶させる段階を含む。
【００２６】
第２の本発明によると、作用極及び対極を具備する検出電極と、前記作用極と前記対極との間に流れる電流を検出する電流検出手段と、を有し、前記作用極及び前記対極のそれぞれの少なくとも一部を検水に接触させて、前記作用極と前記対極との間の残留塩素還元電流を検出して検水中の残留塩素濃度を検出する残留塩素濃度測定装置において、前記作用極と前記対極との間に残留塩素還元電圧又は酸素還元電圧を選択的に印加する電圧印加手段と；溶存酸素を飽和させた検水に対する、前記作用極と前記対極との間に酸素還元電圧を印加した際の前記作用極と前記対極との間の酸素還元電流の検出値に基づいて、検水に対する前記検出電極の残留塩素検出感度を求める演算手段と；を有することを特徴とする残留塩素濃度測定装置が提供される。
【００２７】
第２の本発明の好ましい一実施態様によると、残留塩素濃度測定装置は更に、前記検出電極が接触する検水の温度を検出する温度検出手段と；前記検出電極の残留塩素検出感度と溶存酸素検出感度との相関を示す第１の情報、飽和溶存酸素濃度と液温との関係を示す第２の情報、及び前記検出電極の当初の残留塩素検出感度を示す第３の情報を記憶するための記憶手段と；を有し、前記演算手段は、前記第１の情報及び前記第３の情報に基づいて算出される前記検出電極の当初の溶存酸素検出感度と、前記作用極と前記対極との間の酸素還元電流の検出値、前記温度検出手段による検水温度の検出値、及び前記第２の情報に基づいて算出される検水に対する前記検出電極の溶存酸素検出感度と、の相関を求めて、該相関に基づいて、前記第３の情報から検水に対する前記検出電極の残留塩素検出感度を求める。
【００２８】
第２の本発明の一実施態様によると、残留塩素濃度測定装置は更に、前記記憶手段に対する情報の書き込み手段を有し、該書き込み手段は、前記演算手段が求めた検水に対する前記検出電極の残留塩素検出感度を示す情報を、前記記憶手段に記憶させる。そして、好ましい一実施態様によると、所望により、前記記憶手段に記憶された検水に対する前記検出電極の残留塩素検出感度を示す情報を用いて、検水中の残留塩素濃度が求められる。
【００２９】
第２の本発明の他の実施態様によると、前記検出電極は装置本体に対して着脱可能であり、前記残留塩素濃度測定装置は、前記記憶手段として、装置本体に取り付けられた第１の記憶手段と、前記検出電極又は前記検出電極を装置本体に対して接続するためのコネクタ若しくはケーブルに取り付けられた第２の記憶手段と、を有し、少なくとも前記第１の情報及び前記第２の情報は前記第１の記憶手段に記憶され、少なくとも前記第３の情報は前記第２の記憶手段に記憶される。そして、一実施態様では、残留塩素濃度測定装置は更に、前記第２の記憶手段に対する情報の書き込み手段を有し、該書き込み手段は、前記演算手段が求めた検水に対する前記検出電極の残留塩素検出感度を示す情報を、前記第２の記憶手段に記憶させる。好ましい一実施態様によると、所望により、前記第２の記憶手段に記憶された検水に対する前記検出電極の残留塩素検出感度を示す情報を用いて、検水中の残留塩素濃度が求められる。
【００３０】
【発明の実施の形態】
以下、本発明に係る残留塩素濃度測定装置の校正方法及び残留塩素濃度測定装置を図面に則して更に詳しく説明する。
【００３１】
図１に本発明を適用し得る残留塩素濃度測定装置の一実施例を示す。残留塩素濃度測定装置１は、ポーラログラフ法を用いる検出電極、即ち、残留塩素電極１０と、この残留塩素電極１０からの信号を処理し、表示する装置本体２０とを備え、残留塩素電極１０はケーブル１６を介してコネクタ１７にて装置本体２０に着脱自在に接続される。
【００３２】
図２をも参照すると、残留塩素電極１０がより詳しく示されており、本実施例では、残留塩素電極１０は、電極本体１１に保持された、検出部たる中空の概略細長円筒形状の電極支持体１２に作用極１３と対極１４とを有している。残留塩素電極１０は、露出型残留塩素電極であり、作用極１３及び対極１４は、その少なくとも一部が、電極支持体１２の外表面に露出し、検水に接触するようになっている。
【００３３】
本実施例では、作用極１３は金又は白金とされ、対極１４には、銀又は銀・塩化銀を使用する。作用極１３は、ロッド形状のものを電極支持体１２の外周壁に圧入して取り付けるか、或いは接着、注型により取り付けることができる。一方、対極１４は、例えば、線状電極部材を電極支持体１２の外周面に螺旋状に巻き付けることにより設けることができる。
【００３４】
作用極１３及び対極１４には、それぞれリード線１３ａ、１４ａの一端が接続され、これらリード線１３ａ、１４ａの他端は、電極支持体１２の中心穴１２ａ内を通って、電極本体１１内に設けられた配線用プリント基板（図示せず）に接続され、ケーブル１６、コネクタ１７の対応する接点１７ａを介して装置本体２０に接続される。
【００３５】
又、電極支持体１２の中心穴１２ａ内には、サーミスタや白金測温体のような温度検出手段たる温度測定素子１５が配置され、リード線１５ａにより上記配線用プリント基板（図示せず）に接続され、ケーブル１６、コネクタ１７の対応する接点１７ａを介して装置本体２０に接続される。
【００３６】
図３をも参照すると、本実施例の残留塩素濃度測定装置１の概略制御ブロックが示されている。装置本体２０は、装置動作を統括制御する本実施例ではマイクロコンピュータとされる演算制御手段２１、演算制御手段２１が従う後述の残留塩素濃度測定手順及び校正手順を示すプログラム、及び各種データを記憶するための第１の記憶手段２２、電源２３から電力が供給されて作用極１３と対極１４との間に演算制御手段２１の指示に従い所定の電圧を印加する電圧印加手段２４、作用極１３と対極１４との間に流れる電流を検出して検出信号を演算制御手段２１に入力する電流検出手段（電流計）２５、電流検知手段２５からの入力信号に応じて演算制御手段２１が演算処理することで求めた残留塩素濃度の測定結果、装置状態等を表示するための本実施例では液晶表示パネルとされる表示部２６、残留塩素濃度測定動作・校正動作の開始／停止、各種データの入力等を行うための入力手段たる操作部２７を有する。
【００３７】
本実施例では、電圧印加手段２４は、詳しくは後述するように、演算制御手段２１の指示により、作用極１３と対極１４との間に、残留塩素を測定できる印加電圧、即ち、所定の残留塩素還元電圧（測定用印加電圧；通常、−２００ｍＶ〜＋１００ｍＶ。本実施例では−１００ｍＶ）、又は溶存酸素を測定できる印加電圧、即ち、所定の酸素還元電圧（校正用印加電圧；通常、−４５０ｍＶ〜−６５０ｍＶ。本実施例では−５５０ｍＶ）を選択的に切り替えて印加できるようになっている。そして、電流検出手段２５は、作用極１３と対極１４との間に上記所定の残留塩素還元電圧を印加した際の残留塩素電極１０の出力（以下「残留塩素検出出力」という。）と、作用極１３と対極１４との間に上記所定の酸素還元電圧を印加した際の残留塩素電極１０の出力（以下「溶存酸素検出出力」という。）を、演算制御手段２１に入力する。
【００３８】
又、本実施例では、残留塩素電極１０には、後述するように残留塩素電極１０の感度校正のために必要なデータを記憶するための第２の記憶手段１８が設けられている。第２の記憶手段１８は、本実施例では、残留塩素電極１０を装置本体２０に接続するためのケーブル１６の先端に取り付けられたコネクタ１７内に設けられたメモリ回路とされる。別法として、第２の記憶手段１８は、図６に示すように、残留塩素電極１０の電極本体１１内で、例えば上記配線用プリント基板等の上に設けてもよい。
【００３９】
第２の記憶手段１８としては、ＥＥＰＲＯＭ、フラッシュメモリー、電池バックアップ突きＲＡＭ、ＥＰＲＯＭ、更にはワンタイムＲＯＭ等を使用することができる。
【００４０】
残留塩素電極１０が適正に装置本体２０に接続されると、装置本体２０に設けられた電圧印加手段２４、電流検出手段２５は、残留塩素電極１０の作用極１３、対極１４に接続されたリード線１３ａ、１４ａと接続される。又、同様に残留塩素電極１０が適正に装置本体２０に接続されると、温度測定素子１５に接続されたリード線１５ａは、装置本体２０が備えるインターフェイス（図示せず）を介して演算制御手段２１の入力に接続され、更に第２の記憶手段１８は演算制御手段２１と通信可能となる。本実施例では、装置本体２０は、第２の記憶手段１８に対する情報の読み込み／書き込み手段（図示せず）を備え、情報の読み込み／書き込みができるようになっている。
【００４１】
残留塩素濃度の測定時には、残留塩素電極１０を、例えばプール、池、或いはカット野菜などの食料品の洗浄、殺菌液の入ったシンク等の所望の測定箇所、或いはビーカーやバケツなどに採水された検水中に浸漬する。操作部２７に設けられた測定開始キーを押すと、演算制御手段２１の指示により、電圧印加手段２３から作用極１３と対極１４との間に所定の残留塩素還元電圧、本実施例では−１００ｍＶが印加される。そして、このとき作用極１３における検水中の残留塩素の還元反応、対極１４における銀の酸化反応により、検水の残留塩素濃度に応じて作用極１３と対極１４との間に流れる残留塩素還元電流を、電流検出手段２５によって検出する。演算制御手段２１は、電流検出手段２５から入力された検出電流値を、詳しくは後述するような、利用可能な検水に対する残留塩素電極１０の残留塩素濃度検出感度情報に基づいて検水中の残留塩素濃度を示す信号に変換する。そして、演算制御手段２１は、求めた残留塩素濃度を表示するための信号を表示部２６に送信し、表示部２６にて表示させる。又、測定結果は、装置本体２０が備えるか或いは装置本体２０に通信可能に接続されたプリンターを介して印字し出力してもよい。
【００４２】
前述のように、作用極１３と対極１４とが直接検水に接触する露出型残留塩素電極は、検水の水質（ｐＨ、ＥＣ、汚れ等）が変化すると、その影響が電極の出力に現れ、作用極１３及び／又は対極１４の消耗或いは汚れの付着等によって電極感度が変化していなくても、検水の水質の影響で電極感度が変化する。
【００４３】
従って、電極の感度校正を行う必要があるが、従来一般的に行われている所定の濃度の残留塩素を含有する標準液を用いた校正方法では、標準液の不安定さに起因する煩雑さ、正確性の問題に加えて、対象の検水と標準液とで水質が異なる場合に、測定値に誤差を生じるという問題がある。
【００４４】
そこで、本発明によれば、校正時に残留塩素電極１０によって検水の飽和溶存酸素濃度を測定することで、残留塩素検出感度に変換し、残留塩素電極１０の感度校正を行う。
【００４５】
図５を参照して説明すると、本発明者らは、多くの実験研究を通して、（ｉ）所定の濃度の残留塩素を含有する残留塩素標準液を用いて測定した残留塩素検出出力の検量線の傾き（即ち、残留塩素検出感度）Ａ［μＡ／ｍｇ／Ｌ］（図５（ａ））と、（ｉｉ）同標準液にエアバブリング（空気曝気）を行い溶存酸素を飽和させたものを用いて測定した溶存酸素検出出力の検量線の傾き（即ち、溶存酸素検出感度）Ｂ［μＡ／ｍｇ／Ｌ］（図５（ｂ））と、の間に略一定の比例関係（Ｂ＝αＡ；αは相関係数）が成立することを見出した。
【００４６】
このため、例えば製品工場出荷時に、残留塩素標準液に対する残留塩素電極１０の当初の残留塩素検出感度Ａ（図５（ａ））を測定しておけば、これに上記相関係数αを乗じることにより、残留塩素電極１０の計算上の当初の溶存酸素検出感度Ｂ（図５（ｂ））を求めることができる。
【００４７】
そして、残留塩素濃度の測定が所望される対象の検水に対する残留塩素電極１０の感度校正に際しては、検水（残留塩素濃度未知）にエアバブリングを行い溶存酸素を飽和させ、作用極１３と対極１４との間に所定の酸素還元電圧を印加して溶存酸素検出出力を測定すると共に、その検水の液温を測定してその液温から求められる飽和溶存酸素濃度を求め、検水に対する残留塩素電極１０の溶存酸素検出感度Ｃ［μＡ／ｍｇ／Ｌ］（図５（ｃ））を実測する。ここで求められた溶存酸素検出感度Ｃは、検水の水質（ｐＨ、ＥＣ、汚れ等）の影響を含んだ値となる。
【００４８】
これにより、残留塩素標準液に対する当初の残留塩素検出感度Ａから求めた計算上の当初の溶存酸素検出感度Ｂと、検水に対して実測した溶存酸素検出感度Ｃとから、これら感度ＢとＣとの相関、即ち、変化率β［％］を算出することができる（β＝Ｃ÷Ｂ×１００）。この変化率βは、検水の水質の影響度合いを意味することになる。
【００４９】
そして、上記変化率βを、工場出荷時に求めた当初の残留塩素検出感度Ａ（図５（ａ））に乗じることで、検水の水質の影響を補正した残留塩素検出感度Ｄ［μＡ／ｍｇ／Ｌ］（図５（ｄ））を求めることができる（Ｄ＝Ａ×β÷１００）。
【００５０】
このように、検水に対する溶存酸素検出出力を測定することにより、検水の水質条件（ｐＨ、ＥＣ、汚れ等）からの影響度合いを算出し、残留塩素濃度測定時の誤差要因を補正することができる。
【００５１】
即ち、本発明の一態様によると、本発明に係る残留塩素濃度測定装置１の校正方法は、次の各段階を含んで成る。
【００５２】
（ｉ）予め、残留塩素電極１０の残留塩素検出感度と溶存酸素検出感度との相関係数αを求める。
【００５３】
（ｉｉ）作用極１３と対極１４との間に残留塩素還元電圧を印加して、所定の濃度の残留塩素を含有する標準液に対する作用極１３と対極１４との間の残留塩素還元電流を検出し、残留塩素電極１０の当初の残留塩素検出感度Ａを求める。
【００５４】
（ｉｉｉ）上記相関係数αを示す情報と、残留塩素電極１０の当初の残留塩素検出感度Ａを示す情報と、に基づいて残留塩素電極１０の計算上の当初の溶存酸素検出感度Ｂを求める。
【００５５】
（ｉｖ）作用極１３と対極１４との間に酸素還元電圧を印加し、エアバブリングにより溶存酸素を飽和させた対象検水に対する作用極１３と対極１４との間の酸素還元電流を検出すると共に、検水温度を検出し、飽和溶存酸素濃度と液温との関係を示す既知の情報から検水中の溶存酸素濃度を求めて、検水に対する残留塩素電極１０の溶存酸素検出感度Ｃを求める。
【００５６】
（ｖ）残留塩素電極１０の計算上の当初の溶存酸素検出感度Ｂと、検水に対する実測による残留塩素電極１０の溶存酸素検出感度Ｃとの相関（変化率β）を求める。
【００５７】
（ｖｉ）上記変化率βを示す情報と、残留塩素電極１０の当初の残留塩素検出感度Ａを示す情報と、に基づいて検水に対する残留塩素電極１０の残留塩素検出感度Ｄを求める。
【００５８】
斯かる校正手順に従うことにより、検水に対する残留塩素電極１０の感度校正を行う際に、不安定で扱い難い残留塩素含有標準液や、他の分析方法を使用することなく、単に対象の検水にエアバブリングを行い溶存酸素を飽和させ、この検水に対する溶存酸素検出出力を測定するだけで、極めて簡易に残留塩素電極１０の感度校正を行うことができる。
【００５９】
又、予め求められている残留塩素電極１０の残留塩素検出感度と溶存酸素検出感度との相関（相関係数α）を用いることで、製品工場出荷時には、各電極毎に溶存酸素を飽和させた標準液に対する溶存酸素検出出力を測定しなくてよく、工場出荷時の工程数の削減、コスト低減を実現することができる。
【００６０】
以下、本実施例の残留塩素濃度測定装置１に即して、本発明に係る残留塩素濃度測定装置の校正方法を更に説明する。
【００６１】
図４をも参照して、本実施例では、装置本体２０の第１の記憶手段２２には、残留塩素濃度の測定手順、校正手順、相関係数α、飽和溶存酸素濃度と液温との関係を示す情報が、装置本体２０の製造時若しくは工場出荷時に専用の治具等を用いて予め記憶される。
【００６２】
表１は、所定の残留塩素標準液を用いて測定した残留塩素検出感度Ａと、同標準液にエアバブリングを行って溶存酸素を飽和させたものを用いて測定した溶存酸素検出感度Ｂとを、本実施例に従う実質的に同一の構成を有する複数の残留塩素電極１０について調べた結果を示す。
【００６３】
【表１】

【００６４】
表１に示すように、複数の残留塩素電極１０について、相関係数αは略一定であることが分かる。本実施例では、多くの実験を通して求めた値の平均値である、相関係数α＝５０を用いる。勿論、本発明は、これに限定されるものではない。本発明者らの多くの実験研究によると、通常、αは４０〜６５程度となる。
【００６５】
従って、本実施例では、計算上の当初の溶存酸素検出感度Ｂは、下記式、

のように算出することができる。本実施例では、これら相関係数α及び計算式は、校正手順（ソフト）に組み込んで第１の記憶手段２２に予め記憶される。そして、必要に応じて、演算制御手段２１が、この手順に従って当初の残留塩素検出感度Ａから計算上の当初の溶存酸素検出感度Ｂを算出する。
【００６６】
又、装置本体２０の第１の記憶手段２２に予め記憶させる飽和溶存酸素濃度と液温との関係を示す情報としては、例えば、文献にて既知のものを用いることができる。例えば、表２は、Ｇ．Ａ．Ｔｒｕｅｓｄａｌｅｅｔａｌ“ＴｈｅｓｏｌｕｂｉｌｉｔｙｏｆＯｘｙｇｅｎｉｎＰｕｒｅＷａｔｅｒａｎｄＳｅａ−ｗａｔｅｒ” Ｊ．Ａｐｐｌ．Ｃｈｅｍ．，Ｖｏｌ．５，Ｎｏ．２，Ｐ５３〜６２，１９５５に記載される飽和溶存酸素濃度と液温との関係の抜粋を示す。
【００６７】
【表２】

【００６８】
本実施例では、斯かる飽和溶存酸素濃度と液温との関係は、数式化して、校正手順に組み込んで第１の記憶手段２２に予め記憶させる。そして、必要に応じて演算制御手段２１が、検水の液温から飽和溶存酸素濃度を算出する。
【００６９】
一方、本実施例では、残留塩素電極１０のコネクタ１７に内蔵された第２の記憶手段１８には、工場出荷時に、実測した当初の残留塩素検出感度Ａ［μＡ／ｍｇ／Ｌ］が、専用の治具等を用いて記憶される。
【００７０】
尚、残留塩素電極１０の残留塩素検出出力、溶存酸素検出出力には、それぞれ下記表３に示すような温度特性がある。表３は、残留塩素検出感度、残留塩素検出感度について、２５℃での感度（検量線傾き）を基準としたときの変化率を示す。
【００７１】
【表３】

【００７２】
従って、斯かる温度特性を考慮して、当初の残留塩素検出感度Ａ、検水に対する溶存酸素検出感度Ｃを算出する。本実施例では、工場出荷時において、当初の残留塩素検出感度Ａは、基準温度２５℃に正規化されて第２の記憶手段１８に記憶される。
【００７３】
又、斯かる温度特性（温度係数）を示す情報は、本実施例では、装置本体２０の第１の記憶手段２２に予め記憶され（残留塩素電極１０の第２の記憶手段１８に記憶させてもよい。）、演算制御手段２１は、必要に応じて、温度測定素子１５で測定した検水の液温から、検水に対する溶存酸素検出感度Ｃを基準温度２５℃に正規化して算出する。更に、残留塩素の測定時においては、温度測定素子１５による検水の液温の測定値から、検水に対する残留塩素検出感度Ｄを補正して用い、残留塩素濃度を算出する。
【００７４】
さて、残留塩素電極１０の感度校正時には、
（１）先ず、適当なビーカーやバケツに採水された対象の検水をエアバブリングし、溶存酸素を飽和させる。
【００７５】
（２）そして、溶存酸素が飽和された検水中に残留塩素電極１０を浸漬して、残留塩素測定装置１の操作部２７に設けられた校正開始キー、或いは印加電圧選択キーを押すことにより、印加電圧を校正用印加電圧、即ち、酸素還元電圧（本実施例では−５５０ｍＶ）に切り替える。これにより、演算制御手段２１の指示によって電圧印加手段２４は作用極１３と対極１４との間に電圧を印加する。演算制御手段２１は、第１の記憶手段２２に記憶された校正手順に従って、電極出力の安定化の判断等を経て、溶存酸素検出出力を実測する。本実施例では、溶存酸素検出出力に関して、１０秒あたりの電流値変化が±１μＡであれば電流値が安定したと判断して、最終読み取り値（又は１０秒間の平均値）を安定値とする。ここでは、溶存酸素検出出力は、３４．５［μＡ、２５℃において］であったものとする。
【００７６】
（３）同時に、演算制御手段２１は、残留塩素電極１０に設けられた温度測定素子１５による検水の液温の検出信号を入力し、飽和溶存酸素濃度と液温との関係を示す既知の情報から、検水の飽和溶存酸素濃度を求める。ここでは、液温は２５℃であったものとし、このとき、検水の飽和溶存酸素濃度は、表２から８．１１ｍｇ／Ｌと求まる。
【００７７】
（４）これにより、演算制御手段２１は、上記（２）における溶存酸素を飽和させた検水に対する溶存酸素検出出力の実測値と、上記（３）におけるその検水の飽和溶存酸素濃度の計算値とから、下記式、

のように、校正手順に従って検水に対する溶存酸素検出感度Ｃを算出する。これは、一時、演算制御手段２１が備える記憶部に記憶される。
【００７８】
（５）一方、演算制御手段２１は、残留塩素電極１０の第２の記憶手段１８に記憶されている当初の残留塩素検出感度Ａを読み込む。ここでは、当初の残留塩素検出感度Ａは、０．１００［μＡ／ｍｇ／Ｌ］であったものとする。そして、上記式（１）に従って、下記式、

のように、計算上の当初の溶存酸素検出感度Ｂを算出する。これは、一時、演算制御手段２１が備える記憶部に記憶される。
【００７９】
（６）次いで、演算制御手段２１は、検水の水質の影響度合い、即ち、上記（５）における計算上の当初の溶存酸素検出感度Ｂと、上記（４）における検水に対する溶存酸素検出感度Ｃとの変化率βを、下記式、

のように、校正手順に従って算出する。
【００８０】
（７）そして、演算制御手段２１は、検水の水質の影響を補正した、検水に対する残留塩素検出感度Ｄを、下記式、

のように、校正手順に従って算出する。
【００８１】
こうして求められた、検水に対する残留塩素電極１０の残留塩素検出感度Ｄの情報は、本実施例では、演算制御手段２１が情報読み込み／書き込み手段を介して残留塩素電極１０のコネクタ１７に内蔵された第２の記憶手段１８に記憶させる。
【００８２】
そして、次に行われる残留塩素濃度の測定からは、この第２の記憶手段１８に記憶された検水に対する残留塩素検出感度Ｄを使用して、上述の残留塩素濃度の測定手順に従って、残留塩素濃度を算出し、表示部２６に表示させる。
【００８３】
ここで、残留塩素電極１０の第２の記憶手段１８に記憶できる検水に対する残留塩素検出感度（電極係数）Ｄを複数、例えば、１０個とし、所望時に操作者が操作部２７から指示するなどして、記憶されている残留塩素検出感度Ｄを表示部２６に表示したり、或いはプリンタ等で印字することによって、校正履歴を確認するのに役立てることができる。又、例えば、異なる複数の水質について測定をする場合に、各水質別に上述のようにして求めた残留塩素検出感度Ｄを、所定の水質の検水を指定可能な情報と関係付けて記憶させ、検水の水質が変わる毎に、複数記憶された残留塩素検出感度Ｄを、例えば操作者が操作部２７から選択することにより切り替えて用い、その所定の検水に対する残留塩素濃度を演算することができる。一具体例を挙げれば、水質の異なる複数のプール施設の残留塩素濃度を１台の残留塩素濃度測定装置１で測定する際に、プール施設毎に残留塩素電極１０に設けられた第２の記憶手段１８に記憶させた残留塩素検出感度Ｄを選択して（切り替えて）用いることで、各プール施設に応じて残留塩素濃度を測定することができる。
【００８４】
又、作用極１３及び／又は対極１４の消耗等による電極感度の変動を校正するために、所定の検水に対して定期的に上述のような校正動作を行うことも当然できる。この場合、残留塩素電極１０の第２の記憶手段１８に記憶されている所定の検水に対する残留塩素検出感度（電極係数）を書き換えてもよいし、別の記憶領域に区別して記憶させてもよい。
【００８５】
以上説明した如く、本発明によれば、残留塩素を含有する標準液や、他の分析方法を使用することなく、対象検水の水質（ｐＨ、ＥＣ、汚れ等）の影響を排除して、簡易に残留塩素電極１０の感度校正を行うことができる。
【００８６】
又、定期的に上述のような校正動作を行うことにより、作用極１３及び／又は対極１４の消耗、或いは作用極１３、対極１４への汚れの付着等による感度変動をも校正することができる。
【００８７】
更には、上記変化率βを求めることによって、残留塩素電極１０の残留塩素検出感度の変動を簡易に検知することができるので、例えば残留塩素電極１０の洗浄或いは交換が必要であるか否かを判断等するために、簡易に電極感度をチェックすることができる。このような用途のために、表示部２６に求めた変化率βを表示してもよい。
【００８８】
尚、本実施例のように、当初の残留塩素検出感度Ａ、検水に対する残留塩素検出感度Ｄを残留塩素電極１０が備える記憶手段に記憶させることによって、残留塩素電極１０の寿命による交換、或いは複数の電極をある装置本体２０に対して並行して交換使用するような場合を考えると、電極自体が残留塩素検出感度の情報を保持しているので極めて好都合である。しかし、本発明は、上述して具体的に説明した各種データの記憶態様に限定されるものではない。残留塩素電極１０、装置本体２０にそれぞれ設けられる記憶手段にいずれのデータを記憶させるかは、適宜選択することができ、又、全てのデータを残留塩素電極１０、装置本体２０のいずれかの記憶手段に記憶させてもよい。
【００８９】
又、上述のように、製品工場出荷時に、各残留塩素電極毎に溶存酸素を飽和させた標準液に対する溶存酸素検出出力を測定せず、予め求められた相関係数αを残留塩素濃度測定装置１が備える記憶手段に記憶させることで、工場出荷時の工程数の削減、コスト低減の点で極めて有効である。しかし、所望により、各残留塩素電極１０について、例えば製品工場出荷時に、残留塩素の標準液をエアバブリングしたものに対する溶存酸素検出出力と、その液温から求まる飽和溶存酸素濃度と、から当初の溶存酸素検出をも実測して、各残留塩素電極１０に対する実測による相関係数α又は実測による当初の溶存酸素検出感度Ｂ自体を残留塩素濃度測定装置１（残留塩素電極１０又は装置本体２０）が備える記憶手段に記憶させておいてもよい。そして、これらを上記校正手順におけるそれぞれの代わりに用いることによって、検水に対する残留塩素検出感度Ｄを求めることができる。
【００９０】
【発明の効果】
以上説明したように、本発明によれば、作用極及び対極を具備する検出電極と、作用極と対極との間に流れる電流を検出する電流検出手段と、を有し、作用極及び対極のそれぞれの少なくとも一部を検水に接触させて、作用極と対極との間の残留塩素還元電流を検出して検水中の残留塩素濃度を検出する残留塩素濃度測定装置の校正方法は、溶存酸素を飽和させた検水に対する、作用極と対極との間に酸素還元電圧を印加した際の作用極と対極との間の酸素還元電流を検出することに基づいて、検水に対する検出電極の残留塩素検出感度を求める構成とされるので、
（１）作用極と対極とが直接検水に接触する露出型残留塩素電極の出力を、校正時に残留塩素を含有する標準液或いは他の分析方法を用いることなく、簡易に校正することができる。
（２）作用極と対極とが直接検水に接触する露出型残留塩素電極の感度の、検水の水質の影響による変化を簡易に校正することができると共に、作用極及び／又は対極の消耗、汚れの付着等による変動をも簡易に校正することができる。
といった格別なる効果を奏し得る。
【図面の簡単な説明】
【図１】本発明を適用し得る残留塩素濃度測定装置の一実施例の概略構成図である。
【図２】図１の残留塩素濃度測定装置が備える残留塩素電極の一部切り欠き断面図である。
【図３】図１の残留塩素濃度測定装置の概略制御ブロック図である。
【図４】本発明に係る残留塩素濃度測定装置の校正方法に関する各種データの一記憶態様を説明するための模式図である。
【図５】本発明に係る残留塩素濃度測定装置の校正方法の概念図である。
【図６】本発明を適用し得る残留塩素濃度想定装置の他の実施例の概略構成図である。
【符号の説明】
１残留塩素濃度測定装置
１０残留塩素電極（検出電極）
１１電極本体
１２電極支持体（検出部）
１３作用極
１４対極
１５温度測定素子（温度検出手段）
１６ケーブル
１７コネクタ
１８第２の記憶手段（記憶手段）
２０装置本体
２１マイクロコンピュータ（演算制御手段）
２２第１の記憶手段（記憶手段）
２３電源
２４電圧印加手段
２５電流計（電流検出手段）
２６表示部
２７操作部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally uses a so-called polarographic method, which detects a residual chlorine reduction current using a detection electrode having a working electrode and a counter electrode, and detects the concentration of residual chlorine in a sample solution (water sample). The present invention relates to a calibration method for a residual chlorine concentration measuring device, and a residual chlorine concentration measuring device to which the calibration method is applied, particularly, the working electrode and the counter electrode do not have a diaphragm as a detection electrode and are directly used for water sampling. The present invention relates to a method for calibrating a residual chlorine concentration measuring device provided with an exposed residual chlorine electrode that comes into contact with the device, and a residual chlorine concentration measuring device to which the calibration method is applied.
[0002]
[Prior art]
Conventionally, in order to detect the residual chlorine concentration in a test water, a reduction electrode for residual chlorine is measured at a detection electrode using a so-called polarographic method, that is, a residual chlorine electrode.
[0003]
The residual chlorine concentration measuring device provided with such a residual chlorine electrode is used, for example, for measuring the residual chlorine concentration in pool water or tap water (tap water). For washing and sterilizing foodstuffs such as cut vegetables and fruits, for example, a chlorine sterilizing solution having a relatively high chlorine concentration (about 200 mg / L) obtained by diluting sodium hypochlorite with tap water or groundwater is used. However, the residual chlorine concentration measuring device is used to measure the residual chlorine in the cleaning and sterilizing solution that has entered a sink or the like before and after the cleaning and sterilization.
[0004]
As the residual chlorine electrode, (a) a working electrode and a counter electrode are separated from a sample by a diaphragm, and a diaphragm type residual chlorine electrode in which a space inside the electrode is filled with an electrolyte and the working electrode and the counter electrode are immersed therein, b) There is an exposed residual chlorine electrode in which at least a part of each of the working electrode and the counter electrode is in contact with the sample.
[0005]
The diaphragm-type residual chlorine electrode causes an error when the gas permeating the diaphragm changes the pH of the electrolytic solution, but is basically affected by the pH of the sample, EC (electric conductivity), and the like. There is no advantage. However, the diaphragm type residual chlorine electrode has the following problems. (I) It is necessary to periodically exchange the electrolyte and the diaphragm, and at that time, skill is required to prevent bubbles from entering the electrodes, and maintenance is complicated. (Ii) Responsiveness is poor because residual chlorine permeated through the diaphragm is measured. (Iii) Until the electrode output becomes stable, it is necessary to leave it for about half a day, and the response after maintenance is poor. (Iv) When physical dirt adheres to the diaphragm, an error occurs due to a decrease in the gas permeation amount, and as described above, replacement of the diaphragm is complicated and maintenance is poor. (V) A sealing structure is required in the diaphragm so that the electrolyte does not flow out to the test water, and the structure is complicated.
[0006]
On the other hand, the exposed residual chlorine electrode has the following advantages. (I) Since the working electrode and the counter electrode are exposed, cleaning is easy and maintenance is easy. (Ii) Responsiveness is good because residual chlorine directly reaches the working electrode. (Iii) Even after maintenance (washing), measurement can be performed immediately, and responsiveness after maintenance is good. (Iv) If dirt adheres to the working electrode or the counter electrode, an error may occur due to a change in electric resistance. However, as described above, cleaning is easy and maintainability is good. (V) The structure is simple because it can be constituted substantially only by the working electrode and the counter electrode.
[0007]
Thus, the exposed residual chlorine electrode is superior to the diaphragm electrode in terms of maintainability, responsiveness, simplicity of the structure, and the like.
[0008]
By the way, usually, the electrode sensitivity of the residual chlorine electrode changes due to the consumption of the working electrode and / or the counter electrode when used. Therefore, conventionally, in general, calibration is performed by preparing a standard solution containing a predetermined concentration of residual chlorine and measuring the electrode output with respect to the standard solution to determine the change in electrode sensitivity.
[0009]
However, residual chlorine is a chemically unstable substance, and it is difficult to always prepare a standard solution having a constant concentration. Therefore, in order to perform accurate calibration, it is necessary to determine the residual chlorine concentration of the prepared standard solution, but for that purpose, other analytical methods such as a colorimetric method must be used. In addition, since the concentration of residual chlorine greatly changes with time, it is difficult to prepare and store a standard solution at a time, and it must be prepared each time calibration is performed, and the calibration operation is extremely complicated.
[0010]
Patent Document 1 proposes a residual chlorine meter that facilitates calibration. That is, Patent Literature 1 discloses that span calibration is performed based on the oxygen concentration in the atmosphere instead of using a calibration standard solution containing a predetermined concentration of residual chlorine. However, such prior art relates to a diaphragm-type residual chlorine electrode, and discloses that the sensitivity change due to exhaustion of the counter electrode and the electrolyte is calibrated. However, the water quality (pH, EC, dirt, etc.) of the test sample is disclosed. It does not show anything about calibrating the sensitivity change due to the influence of.
[0011]
[Patent Document 1]
JP-A-2002-116182
[0012]
[Problems to be solved by the invention]
As described above, the exposed-type residual chlorine electrode has many advantages in terms of maintainability, responsiveness, and simplicity of the structure as compared with the diaphragm-type residual chlorine electrode, but has the following problems. Have a point.
[0013]
The exposed-type residual chlorine electrode does not have a diaphragm, and the working electrode and the counter electrode are in direct contact with the test water. Therefore, if the water quality (pH, EC, dirt, etc.) of the test water changes, the effect will be the electrode output. Appears in
[0014]
For this reason, even if the electrode sensitivity does not change due to wear of the working electrode and / or the counter electrode, adhesion of dirt, and the like, the electrode sensitivity changes due to the influence of the quality of the sample water.
[0015]
In the case of an exposed-type residual chlorine electrode, if sensitivity calibration is performed using a standard solution containing residual chlorine as is generally performed in the past, the above-mentioned complicated In addition, in addition to the problem of accuracy, etc., when the water quality of the sample is different from the standard solution, even if the sensitivity calibration is performed with such a standard solution, an error may occur in the measured value due to the influence of the water quality of the sample. There is a problem that occurs.
[0016]
To cope with this problem, it is conceivable to prepare an accurate standard solution under the same water quality conditions as the sample, but it is extremely difficult and not practical to prepare such a standard solution.
[0017]
Therefore, first, the residual chlorine concentration of the test water is measured by another analysis method, and the effect of the water quality of the test water is canceled by adjusting the electrode output to this concentration. Measuring is performed.
[0018]
However, according to such a method, although accurate calibration is possible, the operation is not only complicated but also requires a long time for calibration. Therefore, it is possible to immediately cope with various types of water detection, and it is a problem in realizing a simple device with good portability.
[0019]
The method for span calibration of the electrode sensitivity based on the oxygen concentration in the atmosphere disclosed in the above-mentioned Patent Document 1 is based on a diaphragm in which a working electrode and a counter electrode are electrically connected by an electrolyte filled in the electrode. It can be applied only to the mold electrode, and cannot solve the problems inherent in the above-mentioned exposed chlorine electrode.
[0020]
Therefore, an object of the present invention is to easily output the output of an exposed residual chlorine electrode in which a working electrode and a counter electrode are in direct contact with a sample without using a standard solution containing residual chlorine or another analysis method at the time of calibration. An object of the present invention is to provide a calibration method for a residual chlorine concentration measuring device and a residual chlorine concentration measuring device that can be calibrated.
[0021]
Another object of the present invention is to provide a working electrode and a counter electrode that can directly calibrate a change in sensitivity of an exposed residual chlorine electrode in direct contact with a sample due to the influence of the quality of the sample, and a working electrode and a counter electrode. An object of the present invention is to provide a calibration method of a residual chlorine concentration measuring device and a residual chlorine concentration measuring device which can easily calibrate fluctuations due to exhaustion of a counter electrode, adhesion of dirt, and the like.
[0022]
[Means for Solving the Problems]
The above object is achieved by a method for calibrating a residual chlorine concentration measuring device and a residual chlorine concentration measuring device according to the present invention. In summary, a first aspect of the present invention includes a detection electrode having a working electrode and a counter electrode, and current detecting means for detecting a current flowing between the working electrode and the counter electrode. Calibration of a residual chlorine concentration measuring device for contacting at least a part of each of the counter electrodes with a test water, detecting a residual chlorine reduction current between the working electrode and the counter electrode, and detecting a residual chlorine concentration in the test water. In the method, based on detecting an oxygen reduction current between the working electrode and the counter electrode when an oxygen reduction voltage is applied between the working electrode and the counter electrode with respect to the test water saturated with dissolved oxygen. And determining the residual chlorine detection sensitivity of the detection electrode with respect to the sample water.
[0023]
According to a preferred embodiment of the first present invention, the method for calibrating the residual chlorine concentration measuring device comprises the steps of: (a) determining a correlation between a previously determined residual chlorine detection sensitivity of the detection electrode and a dissolved oxygen detection sensitivity; Determining the initial dissolved oxygen detection sensitivity of the detection electrode based on the initial residual chlorine detection sensitivity of the electrode; and (b) applying an oxygen reduction voltage between the working electrode and the counter electrode to saturate the dissolved oxygen. Detecting the oxygen reduction current between the working electrode and the counter electrode for the sampled water, detecting the temperature of the sampled water, and determining the dissolved oxygen concentration in the sampled water from the relationship between the saturated dissolved oxygen concentration and the liquid temperature. (C) determining the correlation between the initial dissolved oxygen detection sensitivity of the detection electrode and the dissolved oxygen detection sensitivity of the detection electrode with respect to the test water; Of the detection electrode based on the correlation Determining residual chlorine detection sensitivity of the detecting electrode to the test water from the first residual chlorine detection sensitivity; includes the stages.
[0024]
According to one embodiment of the first present invention, the method for calibrating a residual chlorine concentration measuring device further comprises: (i) information indicating a correlation between a residual chlorine detection sensitivity of the detection electrode and a dissolved oxygen detection sensitivity; Information indicating the relationship between the saturated dissolved oxygen concentration and the liquid temperature; and (iii) a residual chlorine reduction voltage is applied between the working electrode and the counter electrode, and the effect on a standard solution containing a predetermined concentration of residual chlorine is applied. Storing information indicating the initial residual chlorine detection sensitivity of the detection electrode obtained by detecting a residual chlorine reduction current between a pole and the counter electrode in a storage unit provided in the residual chlorine concentration measuring device. .
[0025]
According to one embodiment of the first aspect of the present invention, the method for calibrating a residual chlorine concentration measuring apparatus further includes the step of transmitting the obtained information indicating the sensitivity of the detection electrode for detecting the residual chlorine to the test water using the residual chlorine concentration measuring apparatus. And storing the information in a storage means provided in the computer.
[0026]
According to the second aspect of the present invention, there is provided a detection electrode including a working electrode and a counter electrode, and a current detection unit configured to detect a current flowing between the working electrode and the counter electrode. A residual chlorine concentration measuring device for contacting at least a part of each of the test electrodes to detect a residual chlorine reduction current between the working electrode and the counter electrode to detect a residual chlorine concentration in the test water; Voltage applying means for selectively applying a residual chlorine reduction voltage or an oxygen reduction voltage between the working electrode and the counter electrode; and Calculating means for determining the residual chlorine detection sensitivity of the detection electrode for water detection based on a detected value of an oxygen reduction current between the working electrode and the counter electrode when applied. Provided by concentration measuring device It is.
[0027]
According to a second preferred embodiment of the present invention, the apparatus for measuring the concentration of residual chlorine further comprises a temperature detecting means for detecting a temperature of a sample to be brought into contact with the detecting electrode; a sensitivity of detecting the residual chlorine of the detecting electrode; To store first information indicating the correlation with the detection sensitivity, second information indicating the relationship between the saturated dissolved oxygen concentration and the liquid temperature, and third information indicating the initial residual chlorine detection sensitivity of the detection electrode. Storage means; and the calculation means comprises: an initial dissolved oxygen detection sensitivity of the detection electrode calculated based on the first information and the third information; and the working electrode and the counter electrode. Between the detected value of the oxygen reduction current, the detected value of the test water temperature by the temperature detecting means, and the dissolved oxygen detection sensitivity of the detection electrode to the test water calculated based on the second information. Then, based on the correlation, the third Determining residual chlorine detection sensitivity of the detecting electrode to the test water from the information.
[0028]
According to one embodiment of the second present invention, the residual chlorine concentration measuring device further includes a means for writing information to the storage means, wherein the writing means is provided for the detection electrode with respect to the water sample determined by the arithmetic means. Information indicating the residual chlorine detection sensitivity is stored in the storage means. Then, according to a preferred embodiment, the concentration of residual chlorine in the test water is obtained using information indicating the residual chlorine detection sensitivity of the detection electrode with respect to the test water stored in the storage means, if desired.
[0029]
According to another embodiment of the second invention, the detection electrode is detachable from the device main body, and the residual chlorine concentration measuring device is a first storage device attached to the device main body as the storage means. Means, and second storage means attached to a connector or a cable for connecting the detection electrode or the detection electrode to the apparatus main body, and at least the first information and the second information. Is stored in the first storage means, and at least the third information is stored in the second storage means. In one embodiment, the residual chlorine concentration measuring device further includes information writing means for writing information to the second storage means, wherein the writing means comprises: Information indicating the detection sensitivity is stored in the second storage means. According to a preferred embodiment, the concentration of residual chlorine in the test water is determined using information indicating the residual chlorine detection sensitivity of the detection electrode with respect to the test water stored in the second storage means, if desired.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for calibrating a residual chlorine concentration measuring apparatus and a residual chlorine concentration measuring apparatus according to the present invention will be described in more detail with reference to the drawings.
[0031]
FIG. 1 shows an embodiment of a residual chlorine concentration measuring apparatus to which the present invention can be applied. The residual chlorine concentration measuring device 1 includes a detection electrode using a polarographic method, that is, a residual chlorine electrode 10, and a device main body 20 that processes and displays a signal from the residual chlorine electrode 10, and the residual chlorine electrode 10 is a cable. The connector 16 is detachably connected to the apparatus main body 20 via the connector 16.
[0032]
Referring also to FIG. 2, the residual chlorine electrode 10 is shown in more detail. In the present embodiment, the residual chlorine electrode 10 is supported by an electrode main body 11 and has a hollow substantially elongated cylindrical electrode support serving as a detection unit. The body 12 has a working electrode 13 and a counter electrode 14. The residual chlorine electrode 10 is an exposed-type residual chlorine electrode, and at least a part of the working electrode 13 and the counter electrode 14 is exposed on the outer surface of the electrode support 12 and comes into contact with the sample.
[0033]
In this embodiment, the working electrode 13 is made of gold or platinum, and the counter electrode 14 is made of silver or silver / silver chloride. The working electrode 13 can be attached by pressing a rod-shaped one into the outer peripheral wall of the electrode support 12, or can be attached by bonding or casting. On the other hand, the counter electrode 14 can be provided by, for example, spirally winding a linear electrode member around the outer peripheral surface of the electrode support 12.
[0034]
One ends of

lead wires

13a and 14a are connected to the working electrode 13 and the counter electrode 14, respectively, and the other ends of these

lead wires

13a and 14a pass through the center hole 12a of the electrode support 12 and into the electrode body 11. It is connected to the provided printed circuit board for wiring (not shown), and is connected to the apparatus main body 20 via the corresponding contact 17a of the cable 16 and the connector 17.
[0035]
In the center hole 12a of the electrode support 12, a temperature measuring element 15 as a temperature detecting means such as a thermistor or a platinum temperature measuring element is arranged, and is connected to the printed wiring board (not shown) by a lead wire 15a. It is connected to the apparatus main body 20 via the corresponding contact 17a of the cable 16 and the connector 17.
[0036]
FIG. 3 also shows a schematic control block of the residual chlorine concentration measuring device 1 of the present embodiment. The apparatus main body 20 stores arithmetic and control means 21 which is a microcomputer in the present embodiment, which controls the apparatus in its entirety, a program indicating a residual chlorine concentration measurement procedure and a calibration procedure to be described later which the arithmetic and control means 21 follows, and various data. The first storage unit 22 for performing the operation, a voltage application unit 24 that is supplied with power from the power supply 23 and applies a predetermined voltage between the working electrode 13 and the counter electrode 14 according to the instruction of the arithmetic control unit 21, A current detection means (ammeter) 25 for detecting a current flowing between the counter electrode 14 and inputting a detection signal to the arithmetic control means 21, and the arithmetic control means 21 performs arithmetic processing according to an input signal from the current detection means 25. In the present embodiment, a display unit 26, which is a liquid crystal display panel, for displaying the measurement result of the residual chlorine concentration, the device state, etc. Start / stop, having an input unit serving the operation unit 27 for inputting of various data.
[0037]
In the present embodiment, the voltage application means 24 is an applied voltage capable of measuring residual chlorine between the working electrode 13 and the counter electrode 14, that is, a predetermined residual voltage, according to an instruction of the arithmetic control means 21, as described later in detail. Chlorine reduction voltage (applied voltage for measurement; usually -200 mV to +100 mV; -100 mV in this embodiment) or an applied voltage capable of measuring dissolved oxygen, that is, a predetermined oxygen reduction voltage (applied voltage for calibration; usually -450 mV) (-550 mV in this embodiment, -550 mV). Then, the current detecting means 25 outputs the output of the residual chlorine electrode 10 when the predetermined residual chlorine reduction voltage is applied between the working electrode 13 and the counter electrode 14 (hereinafter referred to as “residual chlorine detection output”) and the operation. The output of the residual chlorine electrode 10 when the above-described predetermined oxygen reduction voltage is applied between the electrode 13 and the counter electrode 14 (hereinafter referred to as “dissolved oxygen detection output”) is input to the arithmetic and control unit 21.
[0038]
Further, in this embodiment, the residual chlorine electrode 10 is provided with a second storage means 18 for storing data necessary for the sensitivity calibration of the residual chlorine electrode 10 as described later. In the present embodiment, the second storage means 18 is a memory circuit provided in a connector 17 attached to a distal end of a cable 16 for connecting the residual chlorine electrode 10 to the apparatus main body 20. Alternatively, as shown in FIG. 6, the second storage means 18 may be provided in the electrode main body 11 of the residual chlorine electrode 10, for example, on the printed circuit board for wiring.
[0039]
As the second storage unit 18, an EEPROM, a flash memory, a battery backup RAM, an EPROM, a one-time ROM, or the like can be used.
[0040]
When the residual chlorine electrode 10 is properly connected to the apparatus main body 20, the voltage applying means 24 and the current detecting means 25 provided on the apparatus main body 20 use the leads connected to the working electrode 13 and the counter electrode 14 of the residual chlorine electrode 10. Connected to

lines

13a and 14a. Similarly, when the residual chlorine electrode 10 is properly connected to the apparatus main body 20, the lead wire 15a connected to the temperature measuring element 15 is connected to the arithmetic control unit via an interface (not shown) provided in the apparatus main body 20. The second storage means 18 can communicate with the arithmetic control means 21. In the present embodiment, the apparatus main body 20 includes information reading / writing means (not shown) for reading / writing information from / to the second storage means 18 so as to read / write information.
[0041]
At the time of measuring the residual chlorine concentration, the residual chlorine electrode 10 is sampled at a desired measuring point such as a pool, a pond, a washing of foodstuffs such as cut vegetables, a sink containing a sterilizing solution, or a beaker or a bucket. Immersed in the test water. When a measurement start key provided on the operation unit 27 is pressed, a predetermined residual chlorine reduction voltage is applied between the working electrode 13 and the counter electrode 14 from the voltage applying unit 23 according to an instruction from the arithmetic control unit 21, and in this embodiment, −100 mV. Is applied. At this time, the residual chlorine reduction current flowing between the working electrode 13 and the counter electrode 14 according to the residual chlorine concentration of the sample water due to the reduction reaction of residual chlorine in the test water at the working electrode 13 and the oxidation reaction of silver at the counter electrode 14. Is detected by the current detecting means 25. The arithmetic control unit 21 determines the detected current value input from the current detection unit 25 based on the residual chlorine concentration detection sensitivity information of the residual chlorine electrode 10 with respect to the available test water, as described later in detail. Convert to a signal indicating chlorine concentration. Then, the arithmetic and control unit 21 transmits a signal for displaying the obtained residual chlorine concentration to the display unit 26 and causes the display unit 26 to display the signal. Further, the measurement result may be printed and output via a printer provided in the apparatus main body 20 or connected to the apparatus main body 20 in a communicable manner.
[0042]
As described above, the exposed residual chlorine electrode, in which the working electrode 13 and the counter electrode 14 are in direct contact with the water sample, has an effect on the output of the electrode when the water quality (pH, EC, dirt, etc.) of the water sample changes. Even if the electrode sensitivity does not change due to the consumption of the working electrode 13 and / or the counter electrode 14 or the attachment of dirt, the electrode sensitivity changes due to the influence of the quality of the sample water.
[0043]
Therefore, it is necessary to calibrate the sensitivity of the electrode, but the calibration method using a standard solution containing a predetermined concentration of residual chlorine, which is conventionally generally performed, is complicated by the instability of the standard solution. In addition to the problem of accuracy, there is a problem that an error occurs in the measured value when the water quality of the target sample differs from that of the standard solution.
[0044]
Therefore, according to the present invention, the saturation dissolved oxygen concentration of the test water is measured by the residual chlorine electrode 10 at the time of calibration to convert the concentration into the residual chlorine detection sensitivity, and the sensitivity of the residual chlorine electrode 10 is calibrated.
[0045]
Referring to FIG. 5, the present inventors have conducted (i) a calibration curve of a residual chlorine detection output measured using a residual chlorine standard solution containing a predetermined concentration of residual chlorine through many experimental studies. A gradient (that is, residual chlorine detection sensitivity) A [μA / mg / L] (FIG. 5 (a)) and (ii) a solution obtained by performing air bubbling (air aeration) on the same standard solution to saturate dissolved oxygen. Is approximately constant proportional to the slope of the calibration curve of the dissolved oxygen detection output (ie, the dissolved oxygen detection sensitivity) B [μA / mg / L] (FIG. 5 (b)). α is a correlation coefficient).
[0046]
Therefore, for example, if the initial residual chlorine detection sensitivity A of the residual chlorine electrode 10 with respect to the residual chlorine standard solution (FIG. 5 (a)) is measured at the time of shipment from the product factory, the above-mentioned correlation coefficient α is multiplied. Thereby, the calculated initial dissolved oxygen detection sensitivity B (FIG. 5B) of the residual chlorine electrode 10 can be obtained.
[0047]
When the sensitivity of the residual chlorine electrode 10 is to be calibrated with respect to the sample water of which measurement of the residual chlorine concentration is desired, air bubbling is performed on the sample water (residual chlorine concentration unknown) to saturate the dissolved oxygen, and the working electrode 13 and the counter electrode are calibrated. 14 and a predetermined oxygen reduction voltage is applied to measure the dissolved oxygen detection output, and the temperature of the sample is measured to determine the saturated dissolved oxygen concentration determined from the solution temperature. The dissolved oxygen detection sensitivity C [μA / mg / L] of the chlorine electrode 10 (FIG. 5C) is actually measured. The dissolved oxygen detection sensitivity C obtained here is a value including the influence of the water quality (pH, EC, dirt, etc.) of the test water.
[0048]
As a result, from the calculated initial dissolved oxygen detection sensitivity B obtained from the initial residual chlorine detection sensitivity A for the residual chlorine standard solution and the dissolved oxygen detection sensitivity C actually measured for the test water, these sensitivities B and C are obtained. , That is, the change rate β [%] can be calculated (β = C ÷ B × 100). This change rate β means the degree of influence of the water quality of the sampled water.
[0049]
The change rate β is multiplied by the initial residual chlorine detection sensitivity A (FIG. 5 (a)) obtained at the time of shipment from the factory, thereby correcting the effect of the water quality of the sample water to obtain a residual chlorine detection sensitivity D [μA / mg]. / L] (FIG. 5 (d)) (D = A × β ÷ 100).
[0050]
In this way, by measuring the dissolved oxygen detection output for the test water, the degree of influence from the water quality conditions of the test water (pH, EC, dirt, etc.) is calculated, and the error factor at the time of measuring the residual chlorine concentration is corrected. Can be.
[0051]
That is, according to one aspect of the present invention, the calibration method of the residual chlorine concentration measuring device 1 according to the present invention includes the following steps.
[0052]
(I) A correlation coefficient α between the residual chlorine detection sensitivity of the residual chlorine electrode 10 and the dissolved oxygen detection sensitivity is determined in advance.
[0053]
(Ii) A residual chlorine reduction voltage is applied between the working electrode 13 and the counter electrode 14 to detect a residual chlorine reduction current between the working electrode 13 and the counter electrode 14 for a standard solution containing a predetermined concentration of residual chlorine. Then, the initial residual chlorine detection sensitivity A of the residual chlorine electrode 10 is obtained.
[0054]
(Iii) The calculated initial dissolved oxygen detection sensitivity B of the residual chlorine electrode 10 is determined based on the information indicating the correlation coefficient α and the information indicating the initial residual chlorine detection sensitivity A of the residual chlorine electrode 10. .
[0055]
(Iv) An oxygen reduction voltage is applied between the working electrode 13 and the counter electrode 14 to detect an oxygen reduction current between the working electrode 13 and the counter electrode 14 with respect to the target test water in which dissolved oxygen is saturated by air bubbling. Then, the temperature of the test water is detected, the dissolved oxygen concentration in the test water is obtained from known information indicating the relationship between the saturated dissolved oxygen concentration and the liquid temperature, and the dissolved oxygen detection sensitivity C of the residual chlorine electrode 10 for the test water is obtained.
[0056]
(V) The correlation (change rate β) between the initially calculated dissolved oxygen detection sensitivity B of the residual chlorine electrode 10 and the dissolved oxygen detection sensitivity C of the residual chlorine electrode 10 by actual measurement with respect to the water sample is determined.
[0057]
(Vi) The residual chlorine detection sensitivity D of the residual chlorine electrode 10 with respect to the water sample is obtained based on the information indicating the change rate β and the information indicating the initial residual chlorine detection sensitivity A of the residual chlorine electrode 10.
[0058]
By following such a calibration procedure, when performing the sensitivity calibration of the residual chlorine electrode 10 with respect to the test water, simply use the test liquid of the target without using an unstable and difficult-to-handle residual chlorine-containing standard solution or other analysis methods. By simply performing air bubbling to saturate dissolved oxygen and measuring the dissolved oxygen detection output for this sample, the sensitivity calibration of the residual chlorine electrode 10 can be performed very easily.
[0059]
Further, by using the correlation (correlation coefficient α) between the residual chlorine detection sensitivity of the residual chlorine electrode 10 and the dissolved oxygen detection sensitivity determined in advance, the dissolved oxygen was saturated for each electrode when the product was shipped from the factory. It is not necessary to measure the dissolved oxygen detection output for the standard solution, and the number of steps at the time of shipment from the factory and the cost can be reduced.
[0060]
Hereinafter, the calibration method of the residual chlorine concentration measuring device according to the present invention will be further described with reference to the residual chlorine concentration measuring device 1 of the present embodiment.
[0061]
Referring to FIG. 4 as well, in the present embodiment, the first storage means 22 of the apparatus main body 20 stores the procedure for measuring the residual chlorine concentration, the calibration procedure, the correlation coefficient α, the saturated dissolved oxygen concentration and the liquid temperature. Information indicating the relationship is stored in advance using a dedicated jig or the like when the device main body 20 is manufactured or shipped from the factory.
[0062]
Table 1 shows the residual chlorine detection sensitivity A measured using a predetermined residual chlorine standard solution and the dissolved oxygen detection sensitivity B measured using a solution obtained by performing air bubbling on the standard solution to saturate dissolved oxygen. A result obtained by examining a plurality of residual chlorine electrodes 10 having substantially the same configuration according to the present embodiment is shown.
[0063]
[Table 1]

[0064]
As shown in Table 1, it can be seen that the correlation coefficient α is substantially constant for the plurality of residual chlorine electrodes 10. In this embodiment, a correlation coefficient α = 50, which is an average value obtained through many experiments, is used. Of course, the present invention is not limited to this. According to many experimental studies by the present inventors, α is usually about 40 to 65.
[0065]
Therefore, in the present embodiment, the calculated initial dissolved oxygen detection sensitivity B is given by the following equation:

Can be calculated as follows. In the present embodiment, the correlation coefficient α and the calculation formula are incorporated in a calibration procedure (software) and stored in the first storage unit 22 in advance. Then, if necessary, the arithmetic and control unit 21 calculates the calculated initial dissolved oxygen detection sensitivity B from the initial residual chlorine detection sensitivity A according to this procedure.
[0066]
Further, as information indicating the relationship between the saturated dissolved oxygen concentration and the liquid temperature stored in advance in the first storage means 22 of the apparatus main body 20, for example, information known in the literature can be used. For example, Table 2 shows that A. See Truesdale et al, "The solubility of Oxygen in Pure Water and Sea-water", J. Am. Appl. Chem. , Vol. 5, No. 2, P53-62, 1955 shows an extract of the relationship between the saturated dissolved oxygen concentration and the liquid temperature.
[0067]
[Table 2]

[0068]
In the present embodiment, the relationship between the saturated dissolved oxygen concentration and the liquid temperature is converted into a mathematical formula, incorporated into a calibration procedure, and stored in the first storage unit 22 in advance. Then, if necessary, the arithmetic and control unit 21 calculates the saturated dissolved oxygen concentration from the liquid temperature of the sampled water.
[0069]
On the other hand, in the present embodiment, the second storage means 18 built in the connector 17 of the residual chlorine electrode 10 stores the originally measured residual chlorine detection sensitivity A [μA / mg / L] at the time of shipment from the factory. Is stored using a jig or the like.
[0070]
The residual chlorine detection output and the dissolved oxygen detection output of the residual chlorine electrode 10 have temperature characteristics as shown in Table 3 below. Table 3 shows the rate of change of the residual chlorine detection sensitivity and the residual chlorine detection sensitivity based on the sensitivity at 25 ° C. (calibration curve slope).
[0071]
[Table 3]

[0072]
Therefore, in consideration of such temperature characteristics, the initial sensitivity A for detecting residual chlorine and the sensitivity C for detecting dissolved oxygen with respect to sample water are calculated. In this embodiment, at the time of shipment from the factory, the initial residual chlorine detection sensitivity A is normalized to the reference temperature of 25 ° C. and stored in the second storage means 18.
[0073]
In this embodiment, the information indicating the temperature characteristic (temperature coefficient) is stored in advance in the first storage unit 22 of the apparatus main body 20 (the information is stored in the second storage unit 18 of the residual chlorine electrode 10). The arithmetic and control means 21 may calculate the dissolved oxygen detection sensitivity C for the test water from the liquid temperature of the test water measured by the temperature measuring element 15 to a reference temperature of 25 ° C. as necessary. Further, when measuring the residual chlorine, the residual chlorine detection sensitivity D for the test water is corrected and used from the measured value of the liquid temperature of the test water by the temperature measuring element 15 to calculate the residual chlorine concentration.
[0074]
By the way, at the time of the sensitivity calibration of the residual chlorine electrode 10,
(1) First, the sample water sampled in an appropriate beaker or bucket is subjected to air bubbling to saturate dissolved oxygen.
[0075]
(2) Then, the residual chlorine electrode 10 is immersed in the test water saturated with dissolved oxygen, and the calibration start key or the applied voltage selection key provided on the operation unit 27 of the residual chlorine measuring device 1 is pressed. The applied voltage is switched to a calibration applied voltage, that is, an oxygen reduction voltage (−550 mV in this embodiment). As a result, the voltage application unit 24 applies a voltage between the working electrode 13 and the counter electrode 14 according to an instruction from the arithmetic control unit 21. The arithmetic control unit 21 actually measures the dissolved oxygen detection output according to the calibration procedure stored in the first storage unit 22, after determining whether or not the electrode output is stabilized. In this embodiment, if the change in the current value per 10 seconds with respect to the dissolved oxygen detection output is ± 1 μA, it is determined that the current value is stable, and the final read value (or the average value over 10 seconds) is set as a stable value. . Here, the dissolved oxygen detection output is assumed to be 34.5 [μA, at 25 ° C.].
[0076]
(3) At the same time, the arithmetic and control means 21 inputs a detection signal of the temperature of the sampled water by the temperature measuring element 15 provided on the residual chlorine electrode 10 and obtains a known signal indicating the relationship between the saturated dissolved oxygen concentration and the solution temperature. From the information, determine the saturated dissolved oxygen concentration of the test water. Here, it is assumed that the liquid temperature is 25 ° C. At this time, the saturated dissolved oxygen concentration of the test water is obtained from Table 2 as 8.11 mg / L.
[0077]
(4) Accordingly, the arithmetic and control unit 21 calculates the actual measured value of the dissolved oxygen detection output for the test water saturated with dissolved oxygen in (2) and the saturated dissolved oxygen concentration in the test water in (3). From the value, the following formula,

Then, the dissolved oxygen detection sensitivity C for the test water is calculated in accordance with the calibration procedure. This is temporarily stored in the storage unit provided in the arithmetic control unit 21.
[0078]
(5) On the other hand, the arithmetic control unit 21 reads the initial residual chlorine detection sensitivity A stored in the second storage unit 18 of the residual chlorine electrode 10. Here, it is assumed that the initial residual chlorine detection sensitivity A is 0.100 [μA / mg / L]. Then, according to the above equation (1), the following equation:

Then, the calculated initial dissolved oxygen detection sensitivity B is calculated as follows. This is temporarily stored in the storage unit provided in the arithmetic control unit 21.
[0079]
(6) Next, the arithmetic control means 21 determines the degree of influence of the water quality of the test water, that is, the calculated dissolved oxygen detection sensitivity B in the above (5) and the dissolved oxygen detection sensitivity to the test water in the above (4). The rate of change β with C is given by the following equation:

Is calculated according to the calibration procedure.
[0080]
(7) Then, the arithmetic and control unit 21 calculates the residual chlorine detection sensitivity D for the test water by correcting the influence of the water quality of the test water, by the following equation:

Is calculated according to the calibration procedure.
[0081]
In the present embodiment, the information on the residual chlorine detection sensitivity D of the residual chlorine electrode 10 with respect to the water sample obtained in this manner is stored in the connector 17 of the residual chlorine electrode 10 by the arithmetic control means 21 via the information reading / writing means. Stored in the second storage means 18.
[0082]
Then, from the measurement of the residual chlorine concentration to be performed next, using the residual chlorine detection sensitivity D for the water sample stored in the second storage unit 18, the residual chlorine concentration is measured according to the above-described residual chlorine concentration measurement procedure. The density is calculated and displayed on the display unit 26.
[0083]
Here, the residual chlorine detection sensitivity (electrode coefficient) D for the water sample that can be stored in the second storage means 18 of the residual chlorine electrode 10 is set to a plurality, for example, ten, and the operator gives an instruction from the operation unit 27 when desired. Then, by displaying the stored residual chlorine detection sensitivity D on the display unit 26 or by printing it with a printer or the like, it can be useful for confirming the calibration history. Also, for example, when measuring a plurality of different water qualities, the residual chlorine detection sensitivity D obtained as described above for each water quality is stored in association with information that can specify a water sample of a predetermined water quality, Each time the water quality of the test water changes, a plurality of stored residual chlorine detection sensitivities D are used, for example, by being selected by the operator from the operation unit 27 and used to calculate the residual chlorine concentration for the predetermined test water. it can. As one specific example, when the residual chlorine concentration of a plurality of pool facilities having different water qualities is measured by one residual chlorine concentration measuring device 1, the second storage provided in the residual chlorine electrode 10 for each pool facility. By selecting (switching) the residual chlorine detection sensitivity D stored in the means 18 and using it, the residual chlorine concentration can be measured according to each pool facility.
[0084]
In addition, in order to calibrate the fluctuation of the electrode sensitivity due to the consumption of the working electrode 13 and / or the counter electrode 14 or the like, the above-described calibration operation can be performed periodically for a predetermined water sample. In this case, the residual chlorine detection sensitivity (electrode coefficient) for a predetermined sample stored in the second storage means 18 of the residual chlorine electrode 10 may be rewritten, or may be stored separately in another storage area. Good.
[0085]
As described above, according to the present invention, the influence of the water quality (pH, EC, dirt, etc.) of the target test sample is eliminated without using a standard solution containing residual chlorine or other analysis methods. The sensitivity of the residual chlorine electrode 10 can be easily calibrated.
[0086]
In addition, by performing the above-described calibration operation periodically, it is also possible to calibrate sensitivity fluctuations due to wear of the working electrode 13 and / or the counter electrode 14 or adhesion of dirt to the working electrode 13 and the counter electrode 14. .
[0087]
Further, by obtaining the change rate β, a change in the residual chlorine detection sensitivity of the residual chlorine electrode 10 can be easily detected, so that, for example, it is determined whether the residual chlorine electrode 10 needs to be cleaned or replaced. The electrode sensitivity can be easily checked to make a determination or the like. For such an application, the determined change rate β may be displayed on the display unit 26.
[0088]
Note that, as in the present embodiment, the initial residual chlorine detection sensitivity A and the residual chlorine detection sensitivity D for the water sample are stored in the storage means provided in the residual chlorine electrode 10, so that the residual chlorine electrode 10 can be replaced according to its life, or Considering the case where a plurality of electrodes are exchanged and used for a certain apparatus main body 20 in parallel, it is extremely convenient because the electrodes themselves hold information on the sensitivity of detecting residual chlorine. However, the present invention is not limited to the various data storage modes specifically described above. Which data is stored in the storage means provided in each of the residual chlorine electrode 10 and the apparatus main body 20 can be appropriately selected, and all data can be stored in any of the residual chlorine electrode 10 and the apparatus main body 20. The information may be stored in the means.
[0089]
Also, as described above, at the time of shipment from a product factory, the dissolved oxygen detection output for the standard solution saturated with dissolved oxygen for each residual chlorine electrode is not measured, and the previously obtained correlation coefficient α is determined by the residual chlorine concentration measuring device. 1 is extremely effective in reducing the number of processes at the time of factory shipment and cost reduction. However, if desired, for each residual chlorine electrode 10, for example, at the time of shipment from a product factory, the dissolved oxygen detection output for the one obtained by air bubbling of a standard solution of residual chlorine and the saturated dissolved oxygen concentration obtained from the temperature of the solution can be used as the initial dissolved oxygen concentration. The residual chlorine concentration measuring apparatus 1 (the residual chlorine electrode 10 or the apparatus main body 20) is also provided with the actual measurement of the oxygen detection and the actual measured correlation coefficient α for each residual chlorine electrode 10 or the initial dissolved oxygen detection sensitivity B itself. It may be stored in a storage unit. Then, by using these in place of the above in the calibration procedure, the residual chlorine detection sensitivity D for the sample can be obtained.
[0090]
【The invention's effect】
As described above, according to the present invention, a detection electrode including a working electrode and a counter electrode, and a current detection unit for detecting a current flowing between the working electrode and the counter electrode, The calibration method of the residual chlorine concentration measurement device, in which at least a part of each is brought into contact with the test sample and the residual chlorine reduction current between the working electrode and the counter electrode is detected and the residual chlorine concentration in the test sample is detected, Based on detecting the oxygen reduction current between the working electrode and the counter electrode when the oxygen reduction voltage is applied between the working electrode and the counter electrode for the test water saturated with Since it is configured to obtain chlorine detection sensitivity,
(1) The output of the exposed residual chlorine electrode, in which the working electrode and the counter electrode are in direct contact with the sample, can be easily calibrated without using a standard solution containing residual chlorine or another analysis method at the time of calibration. .
(2) The sensitivity of the exposed-type residual chlorine electrode in which the working electrode and the counter electrode are in direct contact with the sample can be easily calibrated for changes due to the influence of the sample water quality, and the working electrode and / or counter electrode are consumed. Also, it is possible to easily calibrate the fluctuation due to the adhesion of dirt and the like.
Such a special effect can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a residual chlorine concentration measuring apparatus to which the present invention can be applied.
FIG. 2 is a partially cutaway sectional view of a residual chlorine electrode provided in the residual chlorine concentration measuring device of FIG.
FIG. 3 is a schematic control block diagram of the residual chlorine concentration measuring device of FIG.
FIG. 4 is a schematic diagram for explaining one storage mode of various data relating to the calibration method of the residual chlorine concentration measuring device according to the present invention.
FIG. 5 is a conceptual diagram of a calibration method of the residual chlorine concentration measuring device according to the present invention.
FIG. 6 is a schematic configuration diagram of another embodiment of a residual chlorine concentration estimation device to which the present invention can be applied.
[Explanation of symbols]
1 Residual chlorine concentration measurement device
10 Residual chlorine electrode (detection electrode)
11 Electrode body
12. Electrode support (detection unit)
13 Working electrode
14 Counter electrode
15 Temperature measuring element (temperature detecting means)
16 Cable
17 Connector
18 Second storage means (storage means)
20 Main unit
21 Microcomputer (arithmetic control means)
22 First storage means (storage means)
23 power supply
24 Voltage application means
25 Ammeter (current detection means)
26 Display
27 Operation section

Claims

A detection electrode having a working electrode and a counter electrode, and current detecting means for detecting a current flowing between the working electrode and the counter electrode, and at least a part of each of the working electrode and the counter electrode is sampled. In contact with, in the calibration method of the residual chlorine concentration measurement device to detect the residual chlorine concentration in the test water by detecting the residual chlorine reduction current between the working electrode and the counter electrode,
Based on detecting an oxygen reduction current between the working electrode and the counter electrode when an oxygen reduction voltage is applied between the working electrode and the counter electrode with respect to the test water saturated with dissolved oxygen, A method for calibrating a residual chlorine concentration measuring device, comprising: determining a residual chlorine detection sensitivity of the detection electrode with respect to water.

(A) Initial detection sensitivity of dissolved oxygen of the detection electrode based on the correlation between the detection sensitivity of residual chlorine and detection sensitivity of dissolved oxygen of the detection electrode obtained in advance and the initial detection sensitivity of residual chlorine of the detection electrode. ,
(B) applying an oxygen reduction voltage between the working electrode and the counter electrode to detect an oxygen reduction current between the working electrode and the counter electrode with respect to the test water saturated with dissolved oxygen; Detect the temperature, determine the dissolved oxygen concentration of the detection electrode for the test water to determine the dissolved oxygen concentration in the test water from the relationship between the saturated dissolved oxygen concentration and the liquid temperature,
(C) calculating the correlation between the initial dissolved oxygen detection sensitivity of the detection electrode and the dissolved oxygen detection sensitivity of the detection electrode with respect to water sample, and from the initial residual chlorine detection sensitivity of the detection electrode based on the correlation; Determine the residual chlorine detection sensitivity of the detection electrode for water detection,
2. The method for calibrating a residual chlorine concentration measuring apparatus according to claim 1, wherein the method includes steps.

Further, (i) information indicating the correlation between the detection sensitivity of residual chlorine and the detection sensitivity of dissolved oxygen of the detection electrode, (ii) information indicating the relationship between the saturated dissolved oxygen concentration and the liquid temperature, and (iii) the working electrode And a detection electrode obtained by detecting a residual chlorine reduction current between the working electrode and the counter electrode with respect to a standard solution containing a predetermined concentration of residual chlorine. 3. The method for calibrating a residual chlorine concentration measurement device according to claim 2, further comprising the step of storing the information indicating the initial residual chlorine concentration detection sensitivity in a storage means provided in the residual chlorine concentration measurement device.

4. The residual chlorine according to claim 2, further comprising the step of storing information indicating the sensitivity of the detection electrode for detecting the residual chlorine with respect to the sampled water in storage means provided in the residual chlorine concentration measuring device. How to calibrate the concentration measuring device.

A detection electrode having a working electrode and a counter electrode, and current detecting means for detecting a current flowing between the working electrode and the counter electrode, and at least a part of each of the working electrode and the counter electrode is sampled. In the residual chlorine concentration measuring device that detects the residual chlorine reduction current between the working electrode and the counter electrode to detect the residual chlorine concentration in the test water,
Voltage applying means for selectively applying a residual chlorine reduction voltage or an oxygen reduction voltage between the working electrode and the counter electrode,
Based on the detected value of the oxygen reduction current between the working electrode and the counter electrode when an oxygen reduction voltage is applied between the working electrode and the counter electrode for the test water saturated with dissolved oxygen, Calculating means for determining the residual chlorine detection sensitivity of the detection electrode with respect to
A residual chlorine concentration measuring device characterized by having:

Furthermore,
Temperature detection means for detecting the temperature of the water sample contacted by the detection electrode,
First information indicating the correlation between the sensitivity of detecting the residual chlorine of the detection electrode and the sensitivity of detecting dissolved oxygen, second information indicating the relationship between the saturated dissolved oxygen concentration and the liquid temperature, and detection of the initial residual chlorine of the detection electrode Storage means for storing third information indicating the sensitivity;
Has,
The calculation means includes an initial dissolved oxygen detection sensitivity of the detection electrode calculated based on the first information and the third information, and a detection value of an oxygen reduction current between the working electrode and the counter electrode. The correlation between the detection value of the sampled water temperature by the temperature detection means, and the dissolved oxygen detection sensitivity of the detection electrode with respect to the sampled water calculated based on the second information, and based on the correlation, 6. The residual chlorine concentration measuring device according to claim 5, wherein a residual chlorine detection sensitivity of the detection electrode with respect to the water sample is obtained from the third information.

Furthermore, it has information writing means for the storage means, and the writing means causes the storage means to store information indicating the residual chlorine detection sensitivity of the detection electrode with respect to the water sample obtained by the arithmetic means. The residual chlorine concentration measuring device according to claim 6, wherein

8. The residual chlorine concentration measuring apparatus according to claim 7, wherein, if desired, the residual chlorine concentration in the test water is determined by using information indicating the residual chlorine detection sensitivity of the detection electrode with respect to the test water stored in the storage means. .

The detection electrode is detachable from the apparatus main body, and the residual chlorine concentration measuring apparatus includes, as the storage means, first storage means attached to the apparatus main body, and the detection electrode or the detection electrode connected to the apparatus main body. A second storage unit attached to a connector or a cable for connecting to the storage unit, at least the first information and the second information are stored in the first storage unit, and at least the 7. The apparatus according to claim 6, wherein the third information is stored in the second storage unit.

Further, there is provided a means for writing information to the second storage means, wherein the writing means stores information indicating the residual chlorine detection sensitivity of the detection electrode with respect to the water sample obtained by the arithmetic means, in the second storage means. 10. The residual chlorine concentration measuring device according to claim 9, wherein the measured value is stored in a storage unit.

11. The residual chlorine concentration in a test water according to claim 10, wherein the information indicating the residual chlorine detection sensitivity of the detection electrode with respect to the test water stored in the second storage means is obtained as desired. Concentration measuring device.