Local amperometric detection of K+ in aqueous solution using scanning electrochemical microscopy ion-transfer voltammetry |
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Institution: | 1. Cardiovascular Centre, ASUITS, Maggiore Hospital, Trieste, Italy;2. Villa Bianca Hospital, Department of Cardiology, Trento, Italy;3. Department of Cardiology, University of Trieste, Trieste, Italy;4. Department of Statistics, University of Trieste, Trieste, Italy;5. Department of Cardiology, University Hospital, Zurich, Switzerland;6. Spedali Civili, Department of Cardiology, Brescia, Italy;7. Department of Cardiology, University Hospital, Parma |
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Abstract: | A robust ultramicroelectrode (UME) probe is described for the amperometric determination of K+ ions in aqueous solution. The approach is based on ion-transfer voltammetry at the interface between two immiscible electrolyte solutions (ITIES), with a liquid ¦ liquid interface formed between a 1,2-dichloroethane solution, containing dibenzo-18-crown-6, in a glass capillary, which is placed in an aqueous K+ salt solution of interest (KCl in this study). The ITIES is externally polarised by applying a potential between silver electrodes in each phase. The UME probe has an inlaid disk geometry, making conventional ultramicroelectrode and scanning electrochemical microscopy (SECM) mass transport models applicable. Limiting current measurements of K+ in aqueous solution show a linear dependence on KCl concentration between 1 × 104 and 2.5 × 103 mol dm3. The K+ microprobe is shown to be particularly suitable for use in SECM, for both approach curve and imaging applications. |
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