Construction of a modified carbon paste electrode for the highly selective simultaneous electrochemical determination of trace amounts of mercury(II) and cadmium(II)

A new chemically modified electrode was synthesized for rapid, simple accurate and highly selective simultaneous determination of mercury and cadmium using square wave anodic stripping voltammetry (SWASV). The electrode was prepared by incorporation of the recently synthesized phosphorous ylide nitro benzoyl diphenylmethylenphosphorane (N-BDMP) in carbon paste electrode. The cations Cd2+ and Hg2+ were preconcentrated on the surface of the modified electrode at −0.900 V vs. Ag/AgCl. They formed complex with N-BDMP and reduced to zero valent metals, and are then reoxidized in stripping step. The limit of detection was found to be 6.6 μg L−1 for Cd(II) and 8.2 μg L−1 for Hg(II) ions. The effects of different cations and anions on the simultaneous determination of Cd2+ and Hg2+ were investigated and found that the electrode is highly selective. The proposed chemically modified electrode was used to the simultaneous determination of Cd2+ and Hg2+ in fish tissue, several plant foodstuffs and water samples.