ION-SELECTIVE ELECTRODES BASED ON P-1-ADAMANTYLCALIX[8] ARENE IONOPHORES FOR THE DETERMINATION OF AMINO-COMPOUNDS

The 'lower rim' functionalized derivatives of p-1-adamantylcalix[8]are ne (octa(trifluoroacetyl-), L(1), and octa(ethoxycarbonylmethoxy-), L( 2), were used as ionophores in PVC membranes of ion-selective electrod es (ISEs). The responses of electrodes towards primary amines (n-octyl amine, 2-phenylethylamine) and amino acid esters are reported. The hos t L(1) failed as ionophore, while the L(2)-based ISE exhibited quasi-N ernstian function (with detection limits at 10(-5) M level) for n-octy lamine and 2-phenylethylamine, as well as for methyl eaters of phenyla lanine and phenylglycine. Addition of lipophilic ionic associate tetra phenylborate-analyte was found to be useful for the enhancing of opera tion stability. Alkali metals and some amines practically do not affec t potentiometric determination of n-octylamine and amino acid esters. In agreement with the concept of H-bonding in the host-guest complex, the interference increases in the following order: tertiary < secondar y < primary amines. Ail ISEs studied exhibit extremely short response time (5-10 s) in wide pH and analyte concentration ranges.