Thallium (I) Selective Membrane Sensor Using Newly Synthesized Podand Derivative of Catechol and Quinoline

The podand chelate, 1,2-bis[2' -(8" -oxyquinoline)ethoxy]-benzene have been synthesized and used as a neutral ionophore to construct an ion selective electrode for the potentiometric determination of thallium ions. Due to the decisive role of solvent mediators, the membranes was fabricated with the plasticizers o-NPOE, DBP, DBBP, TEP, OA, DOP, CN respectively and anionic additive NaTPB. The best of the results were obtained with the membrane electrode composition of o-NPOE:PVC:Ionophore:NaTPB (58%:34%:5%:3%). This sensor exhibits Nernstian response with slope 58.7±0.3 mV decade-1 of activity in concentration range 2.0×10-9 to 1.0×10-1 M Tl(I), performs satisfactorily over wide pH range (2.5-12), with a fast response time (5 s). The sensor was also found to work satisfactorily in partially non-aqueous media up to 40% content of methanol, ethanol, acetone and acetonitrile solution. The Tl(I)-selective electrode was used as an indicator electrode for the titration of TlNO3 with EDTA and KI solution. The selectivity coefficients determined by using fixed interference method (FIM) indicate high selectivity for Tl (I).