Ion-selective electrodes based on l-tryptophan and l-tyrosine

Novel ion-selective electrodes (ISEs) based on amino acids have been developed. l-Tryptophan and l-tyrosine, which are amino acids, are employed as ionophores for solvent polymeric membrane electrodes. The proposed ISEs show rapid Nernstian responses for the Cu2+ ion over the concentration ranges of 3.0 × 10−4–1.0 × 10−1 M. These ISEs exhibit comparatively good selectivity with respect to alkaline, alkaline earth, and some transition and heavy metal ions and the ammonium ion. The ISE based on tryptophan also indicates the Nernstian response for the benzylammonium ion.