A Polymeric Membrane Electrode Based on p-tert-butyl-thiacalix[4]arene Derivative for Thorium Determination

The aim of this study was to construct and characterize an ion selective electrode for the potentiometric determination of thorium ions. On hand study we introduced a new calixarene molecule p-tert-butyl-thiacalix[4]arene derivative as ionophore for thorium(IV) selective polymeric membrane electrode. Due to the decisive role of solvent mediators, we fabricated membranes with the plasticizers DBP, DBBP, TEP, OA, DOP, 1-CN respectively and anionic additive NaTPB. The best of the results were obtained with the membrane electrode composition of DBP:PVC:Ionophore:NaTPB (57%:35%:6%:2%). Electrode sensor shows excellent discrimination towards Th4+ ion in presence of other common cations. The resulting data clarified that the electrode shows a Nernstian slope of 14.9±0.6 mV per decade for Th(IV) ions over a broad working concentration range of 8.0×10-8 to 1.0×10-1 mol/L. Our electrode gives the potential response in 7 sec for whole concentration range and this sensor can be used for seven months. Electrode has been successfully applied for many environmental and biological samples of thorium (IV) and as an indicator in potentiometric titration.