Uranyl Selective Polymeric Membrane Sensor Based on P-Tert-Butyl-Biscalix[4]Arene

In recent years, the monitoring and evaluation of Uranyl (UO2 2+) has received growing attention from both nutritional and toxological points of view. In this experimental study, we revealed that an electroactive material p-tert-butyl-biscalix[4]arene can be used as an ionophore in the preparation of PVC based ion selective electrode and we found that itshows ionophoric binding property for uranyl cation. This electrode shows excellent selectivity for UO2 2+ with respect to most of the common cations including inner transition and heavy metal ions. The proposed membrane sensor with p-tert-butyl-biscalix[4]arene based receptor exhibits wide linear range, with the slope of 29.30±1.0 mV per decade over the concentration range of 8.1×10-8 M-1.0×10-1 M, and membrane sensor shows a lowest detection limit of 8.0×10-8 M of UO2 2+. This sensor satisfactorily works in aqueous media and in non-aqueous media it works upto 40% (water-ethanol, water-methanol, water-acetone and water-acetonitrile). This electrode shows independent response within the pH range of 1.0-5.5 and its fastest response time is 10 s. The proposed membrane electrode was applied successfully for the determination of UO2 2+ in the presence of other cations (binary mixtures) by direct potentiometry and in tap and sea-water samples.