Potassium-ion selective solid contact microelectrode based on a novel 1,3-(di-4-oxabutanol)-calix[4]arene-crown-5 neutral carrier

The development of novel potassium-ion selective microelectrodes using microfabrication technologies and electrochemical polymerization is described. The microelectrode is based on electropolymerized polypyrrole films, doped with cobaltabis(dicarbollide) ions ([3,3′-Co(1,2-C2B9H11)2]), as an internal solid contact layer between the platinum surface and the polymeric sensing membrane. The ion selective membranes, which are based on a plasticized PVC membrane, contain 1,3-(di-4-oxabutanol)-calix[4]arene-crown-5 as a novel potassium ionophore, and are deposited on top of a layer of the conducting PPy[3,3′-Co(1,2-C2B9H11)2]. The response of the microelectrode was linear with a Nernstian slope of 51 ± 2 mV decade−1 over a K+ ion concentration range of 6 × 10−6 to 1 × 10−1 M, with a detection limit of 1.8 × 10−6 M. The microelectrode is suitable for use within the pH range of 3–11. The electrode could be used for at least one month without a considerable alteration in its potential.