Electrodeposition of lead on to a graphite probe for electrothermal atomic absorption spectrometry

A simple system for controlled potential electrodeposition on to a graphite probe electrode is described. Totally pyrolytic graphite was found to be better for electrodeposition than microporous glassy carbon or electrographite coated with pyrolytic graphite. Lead can be deposited by anodic and cathodic processes as PbO₂ and Pb, respectively. Potentials of + 1.2 to + 2.0 V were best for anodic deposition and – 0.8 to– 2.0 V were best for cathodic deposition. With an electrodeposition time of 120 s, AAS sensitivity gains of × 9 and × 3.5 were achieved for anodic and cathodic deposition, respectively, in comparison with the results obtained by direct injection of 20 1 sample volumes on to the probe. The lead cathodic process was unaffected by NaCl concentrations up to 10^–2 M, but only 10^–3 M NaCl could be tolerated by anodic deposition.