PAN-incorporated Nafion-modified spectroscopic graphite electrodes for voltammetric stripping determination of lead Original Research Article

A mercury-free Nafion-modified graphite electrode incorporated with the neutral chelating agent 1-(2-pyridylazo)-2-naphthol (PAN) for voltammetric stripping determination of Pb(II) has been explored. The electrode was fabricated by spin-coating the PAN-containing Nafion polymer onto spectroscopic graphite. The modified electrode exhibited a significantly increased sensitivity and selectivity for Pb(II) compared with a bare spectroscopic graphite electrode. The electrode thus modified also showed some improvement in sensitivity and selectivity for Pb(II) over Cu(II), compared with the electrode modified with pure Nafion. The response of the modified electrode is pH-dependent with the optimum pH being 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. The modified electrodes were less susceptible to peak depression than the bare electrode in the presence of SDS. Triton X-100 was found to greatly depress the voltammetric response at the bare electrode. At the modified electrodes, however, the presence of Triton X-100 resulted in an increase in the voltammetric response, which may be attributed to complexation between Pb(II) and the surfactant.