PAN-INCORPORATED NAFION-MODIFIED SPECTROSCOPIC GRAPHITE-ELECTRODES FOR VOLTAMMETRIC STRIPPING DETERMINATION OF LEAD

A mercury-free Nafion-modified graphite electrode incorporated with th e neutral chelating agent 1-(2-pyridylazo)-2-naphthol (PAN) for voltam metric stripping determination of Pb(II) has been explored. The electr ode was fabricated by spin-coating the PAN-containing Nafion polymer o nto spectroscopic graphite. The modified electrode exhibited a signifi cantly increased sensitivity and selectivity for Pb(II) compared with a bare spectroscopic graphite electrode. The electrode thus modified a lso showed some improvement in sensitivity and selectivity for Pb(II) over Cu(II), compared with the electrode modified with pure Nafion. Th e response of the modified electrode is pH-dependent with the optimum pH bring 3.5-4.0. The electrode can be renewed with HCl solution. The effect of surfactants sodium dodecyl sulfate (SDS) and Triton X-100 on the voltammetric response of the electrodes was also investigated. Th e modified electrodes were less susceptible to peak depression than th e bare electrode in the presence of SDS. Triton X-100 was found to gre atly depress the voltammetric response at the bare electrode. At the m odified electrodes, however, the presence of Triton X-100 resulted in an increase in the voltammetric response, which may be attributed to c omplexation between Pb(II) and the surfactant. (C) 1998 Elsevier Scien ce B.V. All rights reserved.