Facilitated cation transfer at a three-phase junction and its applicability for ionophore evaluation

• Published in: Electrochimica acta Vol. 307; pp. 326 - 333
• Main Authors: Podrażka, Marta, Maciejewska, Julia, Adamiak, Wojciech, Witkowska Nery, Emilia, Jönsson-Niedziółka, Martin
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.06.2019; Elsevier BV
• Subjects: Buckminsterfullerene; Cations; Droplets; Electrodes; Facilitated ion-transfer; Fullerene C60; Fullerenes; Interface between two immiscible electrolyte solutions (ITIES); Pencil graphite electrode; Phase boundaries; Plasticizers; Potassium; Selectivity; Three-phase electrode; Interface between two immiscible electrolyte solutions (ITIES); Three-phase electrode; Pencil graphite electrode; Facilitated ion-transfer; Fullerene C60
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.03.201

Although many redox probes have been used for anion transfer studies in three-phase electrode setups, only a few molecules have been applied for cation transfer. In this work we show that the fullerene C60 is an efficient redox system for this application. We performed ionophore assisted ion-transfer studies in a droplet system, a disposable setup with a cylindrical electrode, as well as a novel paper-based device. The disposable setup is easy to assemble and thanks to the cylindrical electrode creates a more stable and reproducible phase boundary than the standard droplet setup. With this new setup we were able to measure both assisted and unassisted cation-transfer at the three-phase boundary. Additionally, the proposed system was applied to compare the performances of three popular potassium ionophores: Valinomycin, dibenzo-18-crown-6 ether (DB18C6) and Potassium Ionophore III (BME-44). Here, ionophores, normally applied in ion-selective electrodes (ISE), can be easily evaluated and compared without the influence of other components of the ISE membrane such as plasticizers or lipophilic salts. Three-phase ion-transfer voltammetry is a convenient mean to assess the effect of each ionophore on both the selectivity and Gibbs energy of transfer. [Display omitted]