A Novel Ion-Selective Polymeric Membrane Sensor for Determining Thallium(I) with High Selectivity

The study developed a novel ion-selective polymeric membrane sensor using 4'-nitrobenzo-18-crown-6 as an ion carrier, polyvinylchloride as a matrix, and dioctylphthalate as a plasticizer to measure thallium (Tl+) cations in solutions. The sensor demonstrated a Nernstian response within a concentration range of 1.0 × 10−8 to 1.0 × 10−1 M, with a slope of 57.27 mV. While the electrode also responded to Cu2+, Ni2+, and Pb2+ cations, it showed a wider dynamic range and lower detection limit for Tl+ cations. The study investigated various parameters affecting the electrode's response, including pH, cation interferences, and the amounts of ionophore and polyvinylchloride. The electrode was successfully used in complexometric and precipitation titrations of Tl+ with EDTA and KBr, respectively.