Electrolytic analysis

Chemical analysis using electrolysis can be broadly divided into electrolytic separation, which separates and analyzes the test substance or interfering substance in the sample by electrolysis, and coulometric analysis, which determines the amount of electrolyzed substance from the amount of electricity flowing during electrolysis. Electrolytic separation methods include electrogravimetric analysis, which deposits the metal to be measured on an electrode and measures the increase in the mass of the electrode, constant potential electrolysis, internal electrolysis, which uses the difference in ionization tendency without applying an external voltage, and electrograph, which uses an electric current to dissolve ions from a conductive solid sample onto paper soaked in an electrolyte solution and detect them. In some cases, electrolytic separation was limited to electrogravimetric analysis in the early days. Not only metal deposition but also the phenomenon of metal dissolution into a solution is used as an electrolytic phenomenon.

On the other hand, coulometric analysis includes constant-potential coulometric analysis, in which electrolysis is performed at a constant potential, constant-current coulometric analysis, in which the electrolysis current is constant, and coulometric titration, in which a reagent is generated by electrolysis, which is reacted with the test substance, and the amount of reagent generated by the end of the reaction is calculated from the amount of electricity required for electrolysis.

[Takada Takeo]

"Taichiro Fujinaga, Tonoyoshi Nagai, and Soichiro Musha, 'Electrotitration and Electrochemical Analysis' (1967, Kyoritsu Publishing)" ▽ "Shigetaka Suzuki and Takayoshi Yoshimori, 'Electrochemical Analysis - Electrochemical Analysis and Voltammetry' (1987, Kyoritsu Publishing)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

電気分解を利用する化学分析で、試料中の被検物質または妨害物質を電気分解によって分離分析する電解分離法と、電気分解の際に流れた電気量から電解された物質の量を求める電量分析法とに大別できる。電解分離法には、測定すべき金属を電極に析出させ、その電極の質量の増加を測定する電解重量分析法や定電位電解法、外部から電圧をかけずに、イオン化傾向の差を利用する内部電解法、電導性固体試料から電流により電解質溶液をしみ込ませた紙にイオンを溶出させ検出するエレクトログラフ法などがある。初期には電解重量分析のみに限っていた場合もある。電解現象としては金属の析出のみならず、金属を溶液中に溶出させる現象も利用される。

　一方、電量分析法には、定電位で電解を行う定電位電量分析法と、電解電流を一定とする定電流電量分析法、電解によって試薬を発生させ、これと被検物質とを反応させ、反応の終了までに発生した試薬の量を電解に要した電気量から算出する電量滴定法などがある。

［高田健夫］

『藤永太一郎・永井外代士・武者宗一郎著『電気滴定と電解分析』（1967・共立出版）』▽『鈴木繁喬・吉森孝良著『電気分析法――電解分析・ボルタンメトリー』（1987・共立出版）』

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