Potentiometric Aqueous Layer Testing

PANI based SC-ISEs has improved potentiometric characteristics and short-term stability, while underneath the ion selective membrane an aqueous layer had been formed affecting the long-term stability. The formation of these layer was investigated by Pretsch group^{35 (link)} introducing potentiometric aqueous layer test. This test was done to detect the potential drift upon the changing happened from an ALF solution (1.0 × 10⁻³ mol L⁻¹) to the highly concentration interfering ion solution, Antazoline HCl (1.0 × 10⁻² mol L⁻¹) and back then to ALF solution (1.0 × 10⁻³ mol L⁻¹). If the aqueous layer accumulated underneath the ion sensing membrane, potential drift would result from changing the aqueous layer ionic composition.