Novel potentiometric and optical silver ion-selective sensors with subnanomolar detection limits

摘要

Ten Ag⁺-selective ionophores have been characterized in terms of their potentiometric selectivities and complex formation constants in solvent polymeric membranes. The compounds with π-coordination show much weaker interactions than those with thioether or thiocarbamate groups as the coordinating sites. Long-term studies with the best ionophores show that the lower detection limit of the best Ag⁺ sensors can be maintained in the subnanomolar range for at least one month. The best ionophores have also been characterized in fluorescent microspheres. The so far best lower detection limits of 3× 10⁻¹¹M (potentiometrically) and 2 × 10⁻¹¹M Ag⁺ (optically) are found with bridged thiacalixarenes.