Development of Potentiometric Lead Ion Sensors Based on Ionophores Bearing Oxygen/Sulfur-Containing Functional Groups

Potentiometric Pb2+ sensors based on ionophores bearing oxygen/sulfur-containing functional groups, which include anthraquinone, aromatic carboxylic acids, carboxylates, phosphates, and macrocyclic compounds containing amide or thioamide groups, are systematically summarized. Anthraquinone is found to be quickly responsive to lead ions, with the shortest response time of two seconds. Aromatic carboxylic acids with a sulfur atom as an ionophore in an asymmetric membrane respond sensitively to lead ions, with the lowest detection limit of 6.0 × 10−10 M. Phosphate has the advantage of better anti-interference ability, with a logarithmic selectivity coefficient, logK, smaller than −3.0. Macrocyclic amides, after assembly into microelectrodes, have been used as ionophores for the analysis of samples confined in cells of volume 3 μL, with a superior lower detection limit of 2.7 × 10−9 M.