Analytical Sciences

Abstract − Analytical Sciences, 27(1), 1 (2011).

Rapid and Precise Coulometric Determination and Separation of Redox Inert Ions Based on Electrolysis for Ion Transfer at the Aqueous|Organic Solution Interface
Sorin KIHARA* and Megumi KASUNO**
*Kyoto Institute for Interesting Chemistry, 40-5 Sakuradani Kamikazan, Yamashina, Kyoto 607-8466, Japan
**Department of Materials Chemistry, Faculty of Science and Technology, Ryukoku University, Otsu, Shiga 520-2194, Japan
Flow systems for precise and accurate coulometric determinations of ions that were developed on the basis of electrolytic ion transfer at the aqueous|organic solution (W|O) interface are reviewed. The electrolysis cell in the system is composed of a porous poly(tetrafluoroethylene) tube (1.0 mm inner diameter), a metal wire (0.8 mm diameter) inserted into the tube, O into which the tube is immersed, a reference electrode in O and a platinum wire counter electrode in O. The electrolysis is carried out by forcing W containing a species of interest to flow through the narrow gap between the tube and the metal wire. The coulometric determination can be performed with an efficiency of more than 99% and a precision of better than 0.2% based on the ion transfer under an optimum condition, even if the ion is redox inert such as Na+, K+, Mg2+, Ca2+, ClO4, picrate or alkylsulfonates. The system can be applied to selective electrolytic solvent extraction of ions.