Sodium ion-selective electrode based on crown ether-phosphotungstic acid precipitates

Abstract

A sodium ion-selective PVC membrane electrode based on 12-crown-4-phosphotungstic acid precipitates was prepared with dipentyl phthalate as a plasticiser. The electrode gave a linear response with a Nernstian slope (59 mV decade^–1) within the concentration range 10^–1–10^–4M NaCl. The electrode exhibited comparatively good selectivity for sodium with respect to other alkali and alkaline earth metal ions. The effects of the pH of the testing solution, the concentration of the internal solution in the electrode and the composition of the membrane are discussed.