Bis(benzo-15-crown-5) is a potassium selective ionophore. Its potassium ion selectivity is almost equal to that of valinomycin, which is a wellknown neutral carrier for the potassium ion in nature. This reagent, combined with NPOE as a plasticizer, is the most recommended ionophore for potassium-selective PVC membrane electrodes. This ionophore also forms a thallium complex, so it can be used for thallium sensors.
Ion selectivity: LogKt(K/Na):-3.6, LogKpot(K/Rb):-0.7, LogKpot(K/NH4):-2.0, LogKpot(K/Cs):-2.0
Formulation: Ionophore: 2.7%, NPOE: 70%, TFPB: 50 mol% of ionophore/PVC, THF
1. H. Tamura, et al., Thallium(I)-selective PVC Membrane Electrodes Based on Bis(crown ether)s. J Electroanal Chem. 1980;115:115-121.
2. H. Tsukube, et al., Biomimetic Application of Natural Valinomycin and Nonactine Ionophores to Artificial Transport of Amino Acid Salts. Bull Chem Soc Jpn. 1986;59:2021-2022.
3. Y. Yamashoji, et al., Polymer Membrane Thallium(I)-selective Electrodes Based on Dibenzo-crown-6 Ethers. Anal Sci. 1991;7:485-486.