Potentiometric Sensor Selectivity Evaluation

In presence of some interfering ions (K⁺, Na⁺, Ca²⁺, and Mg²⁺) and ALF degradation product was measured to study the sensor selectivity and to determine the extent of foreign substance and its effect on the electrode it was calculated by means of the potentiometric selectivity coefficients (log K_AB). Following IUPAC guidelines evaluating the selectivity coefficients by the use of separate solutions method (SSM)⁵⁹ applying the following equation (eqn (1)), where E_A is the potential measured in 1.0 × 10⁻³ mol L⁻¹ solution of interferent ion and E_B is the potential measured in 1.0 × 10⁻³ mol L⁻¹ solution of primary ion solution. Z is the net charge, F is the Faraday constant, R is the universal gas constant, T is the temperature in Kelvins and a_A is activity of interferent ion A.