Simultaneous potentiometric determination of cations and anions in multiionic solutions using PD-sensors based on MF-4SC and Nafion membranes nanomodified with zirconia and silica

The sensitivity of potentiometric PD-sensors (sensors whose analytical signal is the Donnan potential) based on gradient-modified MF-4SC and Nafion membranes to K+, NH 4 + , CH3COCOO−, HS−, and OH− ions simultaneously present in aqueous solutions has been studied. Hydrated silica and zirconia were used as the dopants. For the simultaneous determination of K+ and NH 4 + cations and CH3COCOO− and HS− anions in alkaline solutions, pairs of cross-sensitive PD-sensors with membranes modified with various dopant concentrations have been used, one of which provides the lowest sensitivity and the other the highest sensitivity of sensor to anions. The best repeatability and reproducibility of the results of determining ion concentrations have been obtained when PD-sensors based on the Nafion membranes doped with ZrO2 where used, which can be explained by the denser and more uniform structure of these membranes when compared to MF-4SC.