Voltammetric determination of heavy metals in natural waters and biological samples by using a chemically modified carbon paste electrode

Abstract

The behaviour of copper, lead and cadmium was studied with a new chemically modified carbon paste electrode, with different supporting electrolytes (HCl, HClO4, H2SO4, NH3-NH4Cl). The optimum conditions for the determination of the above mentioned metals were studied either separately or simultaneously in mixtures of 2 or 3 of them. The method for their simultaneous determination was more sensitive after deposition of a mercury film "in situ" after addition of Hg(II). Detection limits are 5.00 µg l−1, 7.00 µg l−1, 2.00 µg l−1 for copper, cadmium and lead, respectively. The relative standard deviation at a concentration level of 6.00–7.50 ppb, varies within the range 5.00–8.00 % for 90 sec of preconcentration time. Copper, cadmium and lead were determined in synthetic as well as in natural samples by anodic stripping voltammetry (ASV).