Polymeric membrane sodium ion-selective electrodes based on calix[4]arene triesters

New lipophilic triesters of calix[4]arene and calix[4]quinone are investiga ted as sodium ion-selective ionophores in poly(vinyl chloride) membrane ele ctrodes. For an ion selective electrode based on calix[4]arene triester I, the linear response is 1 x 10(-3.5) to 1 x 10(-1) M of Na+ concentrations. The selectivity coefficients for sodium ion over alkali metal and ammonium ions are determined. The detection limit (loga(Na+) = -4.50) and the select ivity coefficient (logK(Na+),(pot)(K+) = -1.86) are obtained for polymeric membrane electrode containing calix[4]arene triester I.