Influence of key parameters on the lower detection limit and response function of solvent polymeric membrane ion-selective electrodes

The lower detection limit of conventional polymeric membrane ion-selective electrodes (ISEs) is given by the release of measuring ions from the sensor membrane into the aqueous sample. It can be greatly improved by using inner solutions of appropriate composition. Recently, steady-state model calculations have been used to predict the influence of various parameters on the response function and the lower detection limit. Among these, effects of the composition of the inner solution, the presence of interfering ions in the sample, the use of a flow-through cell, the polymer content and thickness of the ISE membrane, and the concentration of the membrane components have been investigated in the present work. All observed trends agree fully with the theoretically predicted ones.