Construction and characterization of a lead(II) ion selective electrode with 1-furoil-3,3-diethylthiourea as neutral carrier

Abstract

Lead(II) ion selective electrode, ISE, based on plasticized PVC membranes with 1-furoyl 3,3 diethyl thiourea as ionophore and tributylphosphate as plasticizer have been developed. The membrane was applied on a conducting epoxy resin support. Some parameters of evaluation of the electrode are presented in this work. The ISE have linear response in the concentration range of the 10(-6)-10(-3) mol/dm(3), with slope of 29.61 mV/decade. The static response time obtained was less than 20 seconds. The ISE is useful for more than one month. The selectivity coefficients (K-AB(Pot)) for Cu2+, Cd2+ and Ca2+ ions were calculated by employing the mixed solutions method and the pH dependence of the potential was analyzed. Scanning electron microscopy (SEM) of the membranes was registered at different time of the use of the ISE. The SEM images showed morphological changes of the membrane surface probably due to both the reaction between the Pb2+ and the ionophore and/or loss of the membrane components by exudation.