Selective uranyl ion detection by polymeric ion-selective electrodes based on salphenH2 derivatives

The new ion-selective electrodes (ISEs) based on salphenH2 derivatives such as N,N′-(propylenedioxy)benzenebis(salicylideneimine) L1 and N,N′-4,5-(propylenedioxy)benzenebis(3,5-di-tert-butylsalicylideneimine) L2 as cation carriers are developed for a uranyl ion. The combination of these new ionophores with tris(2-ethylhexyl)phosphate (TEHP) as a plasticizer particularly shows near Nernstian slope in the wide concentration range (1.0 × 10−6 to 1.0 × 10−2 M) of UO22+ and is observed well in the pH range from 1.0 to 5.0 with a response time less than 20 s. Since the employed ionophores were confirmed to form well-defined stable 1:1 complexes with UO22+, the observed high selectivity for a uranyl ion over the other cations was attributed to the selective complexation as well as the lipophilic behavior of these ligands especially for L2. The proposed electrodes offered practically low detection limit of 6.5 × 10−7 M and reasonably good end-points within experimental error were obtained when the sensor was used as an indicator electrode for the potentiometric titration.