Unbiased Selectivity Coefficients of Potentiometric Sensors Using Thin Membrane Layers

Solid‐contact ion‐selective electrodes with thin membranes can more easily achieve complete ion exchange at the sample‐membrane interface, giving unbiased selectivity coefficients. The calculated reconditioning rate corresponds well to experimental data. Alternatively, the redox state of the conducting polymer may be electrochemically switched resulting in primary ion expulsion from the membrane and interfering ion uptake from the sample. Both approaches were tested for tetrabutylammonium‐selective electrodes. The approach's limitations are identified, which includes primary ions impurities in interfering ion salts and an interaction between primary ion and redox polymer. These limitations are visualized with ionophore‐based sodium‐ and silver‐selective electrodes.