Electrochemical properties and analytical advantages of potassium-selective sensor with tungsten trioxide solid contact

A novel solid contact material: tungsten trioxide is proposed for all-solid-state potassium-selective electrode with a typical poly(vinyl chloride) based membrane, intended for potentiometric and coulometric applications. On the contrary to the properties of recently preferred highly hydrophobic solid contact types, hydrophilicity of tungsten trioxide is advantageous from the point of view of both thin water layer effect mitigation and enhanced electroactivity. The proposed sensor offers excellent analytical parameters with wide linear response range, low detection limit and high selectivity. The low frequency capacitance of the solid contact is higher than that of a 'coated wire sensor', moreover, it is advantageously not diminished compared to the solid contact layer not covered by the membrane.