Electrochemical co-detection of As(III), Hg(II) and Pb(II) on a bismuth modified exfoliated graphite electrode

The applicability of a bismuth modified exfoliated graphite (EG) electrode for the co-detection of heavy metal ions -As(III), Hg(II) and Pb(II)-in water samples using square wave anodic stripping voltammetry (SWASV) is reported. Bismuth nanoparticles were deposited on an EG electrode potentiostatically at -1000mV for 300s to form EG-Bi electrode. The Bi modified EG electrode was characterised in 5mM ferrocene and used to as an electrochemical sensor for Pb(II) and Hg(II) individually in 0.1M acetate buffer solution (pH 5) with detection limits (LODs) of 0.83μgL(-1)., 0.46μgL(-1) and limit of quantification of 2.8μgL(-1) and 1.5μgL(-1) respectively. Simultaneous detection of Pb(II), As(III) and Hg(II) was also performed with LODs of 0.053μgL(-1), 0.014μgL(-1), 0.081μgL(-1) and LOQs of 0.18μgL(-1), 0.047μgL(-1) and 0.27μgL(-1) for Pb(II), As(III) and Hg(II) respectively. All the detections were performed under optimised experimental conditions. The stability of the EG-Bi sensor was tested and the electrode was applied to environmental samples. The results found with this method were comparable with those obtained with inductively coupled plasma - optical emission spectrometric technique.