A potassium-ion selective electrode with valinomycin based poly(vinyl chloride) membrane and a poly(vinyl ferrocene) solid contact

The construction of an ion-selective electrode for potassium, employing valinomycin as carrier in a poly(vinyl chloride) membrane and a poly(vinyl ferrocene) solid contact between the membrane and the metallic substrate, is described. The performance of this electrode is compared to electrodes in the coated-wire configuration and the conventional electrode with an aqueous internal reference electrolyte. Nernstian responses were obtained for the three types of electrodes and the selectivities and the detection limits are very similar for all electrodes. The stabilities of these electrodes were investigated over the first 20 days of use. The solid-contact electrode showed a significant improvement for stability compared to the coated-wire electrode and it approaches the performance of the conventional one.