Measuring the selectivity coefficients of a sodium sensor based on ceramic membrane

The paper describes the measurement of selectivity coefficients of a sodium sensor based on ceramic membrane. An acquisition subsystem is realized for this purpose with a high input impedance conditioner (>1000 GΩ). The system is then used to measure voltages from four differently realized sodium sensors, and to determine the selectivity coefficients for three interfering ions. The output voltages are plotted against time to show the evolution of the output signal for different cases. Potassium, calcium and lithium are the interfering ions that have been introduced into the analyzed solution. The four sensors with membranes sintered from 900°C to 1200°C have been characterized. The system is also used with a translating mechanical apparatus to study the evolution of the transient interference