Solid-State Ion-Selective Electrodes Based on Ionic Liquid Solid at Room Temperature for Detecting Amino Acids

An ion-selective electrode based on tetraoctylammonium N-lauroyl sarcosinate ionic liquid, which is solid at room temperature, is responsive to anionic forms of amino acids. Preconditioning in copper sulfate solution and the introduction of more high-melting and hydrophobic ionic liquid (1,3-dihexade-cylimidasolium bromide) allowed the limit of detecting phenylalanine to be lowered by several times (cmin = 2.7 × 10–5 M) and significantly improves the service life of the ion-selective electrode. The possibility was shown for using two ionic liquids for designing ISE with one of them that serves as an inert solid matrix for immobilizing the second one, which in turn ensured the analyte binding and the generation of a potentiometric signal.