Nanomolar determination of Pb(II) ions using a selective templated electrode

A polypyrrole-modified electrode, prepared by electro-polymerization of pyrrole in the presence of methyl red as a dopant, was templated with respect to Pb2+ and applied for the kotentiometric and voltammetric detection of this ion. The templating process improved the analytical response characteristics of the electrode, especially its selectivity with respect to Pb2+. The improvement depended on both the incorporated ligand (dopant) and the templating process, with the latter being more vital. The potentiometric response of the electrode was linear within the Pb2+ concentration range of 2.0x10(-6) to 5.0x10(-2) M with a near-Nernstian slope of 28.6 mV dec(-1) and a detection limit of 7.0x10(-7) M. The electrode was also used for pre-concentration differential pulse anodic stripping voltammetry (DPASV) and the results showed that the peak currents for the incorporated lead species were dependent on the metal ion concentration in the range 1.0x10(-8) to 1.0x10(-3) M. The detection limit of the DPASV method was 3.5x10(-9) M. The selectivity of the electrode with respect to some transition metal ions was investigated. The modified-templated electrode was used for the successful assay of lead in two standard reference material samples.