Nickel hexacyanoferrate membrane as a coated wire cation-selective electrode

Nickel hexacyanoferrates containing alkali metal cations as counter ions we re used to prepare ion-selective electrodes for potentiometric sensing of i ntercalated species in the coated wire electrode (CWE) configuration. All t he electrodes developed display a quasi-Nernstian response towards potassiu m ion, whereas the highest sensitivity is generally achieved when Cs+ is th e counter cation in the sensing material. The selectivity constants of the electrodes were calculated by the matched potential method considering K+ a s the primary ion. The selectivity order is Cs+ > K+ > Na+ > Li+ and reflec ts the effective dimension of the hydrated cations.