Novel Thallium(I)-Selective Membrane Electrode Based on a Podal Ligand

A PVC-based membrane electrode for thallium(I) ions based on 1,21,23,25-tetramethyl-2,20: 3,19-dimetheno- [H, 2] H, 23H, 25H-bis-[1,3] dioxocino[5,4-i:5',4'-i] benzo [1,2-d: 5.4-d'] bis [1,3] benzodioxocin(II) has been prepared. The electrode displays a linear dynamic range of 1.0 x 10^-1-1.0 x 10^-5 M, with a Nernstian slope of 59.8 ± 0.2 mV decad^-1, and a detection limit 5.0 x 10^-6 M. It has a very fast response time of <10 s and can be used for at least ten weeks without a considerable divergence in potentials. This electrode revealed comparatively good selectivity with respect to alkali, alkaline earth, and some transition and heavy metal ions and was effective in a pH range of 2.0-10.0. It was used as an indicator electrode in potentiometric titration of thallium ion with sulfide ion