A novel uranyl ion-selective PVC membrane sensor based on 5,6,7,8-tetrahydro-8-thioxopyrido[4′,3′,4,5]thieno [2,3-d]pyrimidine-4(3H)one

5,6,7,8-Tetrahydro-8-thioxopyrido[4',3',4,5]thieno[2,3-d]pyrimidine-4(3H)one (TTPTP) is used as a novel ionophore in plasticized poly(vinyl chloride) (PVC) matrix membrane sensor for uranyl ions. The sensor displays a rapid and linear response for uranyl ions over the concentration range 1.0 x 10(-1) to 2.0 x 10(-5) mol l(-1) uranyl ion with a Nernstian slope of 30 mV per decade. The sensor response is stable for at least 2 months and exhibits good selectivity for uranyl ion over many inorganic cations and some anions. The TTPTP-based sensor works well in the pH range 2.0-3.5 and successfully employed for determining uranyl ions in 10% non-aqueous medium. The sensor is used for the determination of uranium as uranyl ions in mixtures. The results are compared with those obtained by X-ray fluorescence method. (C) 2003 Elsevier B.V. All rights reserved.