Urea-functionalized calix[4]arenes as carriers for carbonate-selective electrodes

A new PVC membrane electrode for CO32− anion based on urea-functionalized calix[4]arenes (I-IV) as neutral ionophores is prepared. Of the various membranes prepared, the membrane based on bis-urea calix[4]arene I exhibits a linear stable response over a concentration range (5.0 × 10−4 to 1.0 × 10−1) with a slope of −29.2 mV per decade and a detection limit of 1.2 × 10−4 M, and the best selectivity for CO32− anion [KTCO2Jpot=1.9×10−2(sal−)and2.1×10−2(I−)] over salicylate and iodide.