Lead selective electrodes based on thioamide functionalized calix[4]arenes as ionophores

Lead selective electrodes based on a di- and tetrathioamide functionalized calix [4] arene as ionophores were investigated. The Pb(II)-response functions exhibited almost theoretical Nernstian slopes in the activity range 10−6–10−2M of lead ions. For both ionophores a preference for lead over other cations was observed. The best results were obtained for membranes containing the tetrathioamide derivative (ionophore 1), potassium tetrakis(4-chlorophenyl) borate and o-nitrophenyl octyl ether as a plasticizer. This electrode showed greatly improved selectivity over copper, zinc and cadmium ions as compared with commercial solid-state lead selective electrodes.