Role of membrane media in potentiometric selectivity of anion carrier-based ion-selective electrodes

Abstract Effect of membrane media on potentiometric selectivity of two metalloporphyrin anion carriers, manganese(III) and molybdenum(V) complexes of tetraphenylporphyrin, is studied by using liquid membrane cell assemblies. Nitrobenzene, 1,2-dichloroethane, and chloroform are used as liquid membrane media. Anion selectivities of the two metalloporphyrins in nitrobenzene and 1,2-dichloroethane liquid membranes are somewhat different from those of corresponding classical anion exchanger-based liquid membranes, but both solvents cannot induce their anti-Hofmeister behavior. On the other hand, both metalloporphyrins show clear anti-Hofmeister anion selectivity sequences in the less polar chloroform membranes, indicating important roles of membrane media in selective recognition of some anions by the metalloporphyrin anion carriers.