Blank membranes versus ionophore-based membranes for the selective determination of H+.

A pH electrode for the selective determination of H+ was introduced. Both phosphorated calix[6]arene and a N,N'-bisethoxycarbonyl-1,10-diaza-4,7,13,16-tetraoxacyclo-octadecane (DZCE) were used as new H+-ionophores. The calibration graphs of the obtained electrodes exhibits satisfactory Nernstian slopes. The electrodes were compared to blank membranes (without any ionophoric substances) for the first time. Selectivity coefficients of the studied electrodes towards several inorganic cations were calculated. The relative selectivity coefficient (RSC) was applied for evaluating the selectivity properties of H+-electrode using a mathematical equation. The electrodes were applied for the determination of different inorganic and organic acids.