Potentiometric behavior of N,N,N′,N′-tetrabenzylmethylenediamine-based hydrogen ion-selective electrodes

H+-ion selective electrodes (H+-ISE) based on N,N,N′,N′-tetrabenzylalkylenediamine (alkylene: methylene, ethylene, propylene, hexylene) are prepared. We are compared with their response potentials to carbon numbers between diamino groups. They were showed linear selective to hydrogen ion in the range of pH 1.5–9.0, 2.5–9.0, 3.5–9.0 and 4.0–9.0, and their Nernstian slopes were 57.3, 53.5, 57.4 and 56.1 mV pH−1 at 20±0.2°C (theoretical value: 58.2 mV pH−1), respectively. The interference effect on the cations were measured to alkali metal ions, alkaline earth metals ions. Selectivity coefficients were measured by the mixed-solution method. Among all electrodes the N,N,N′,N′-tetrabenzylmethylenediamine (TBMDA)-based electrode has shown the best selectivity in acidic solution.