ADSORPTIVE STRIPPING VOLTAMMETRIC BEHAVIOR OF COLLOIDAL GOLD AND IMMUNOGOLD ON CARBON-PASTE ELECTRODE

A new adsorptive stripping voltammetric method (ASV) for the determina tion of colloidal gold is investigated. The method also allows the mea surement of the average diameter of the particle size and it is based on the previous metal accumulation onto a carbon paste surface electro de followed by an oxidation process of the adsorbed colloid to an Au(I II)-chloro complex which is then electrochemically reduced to Au(0). U sing differential pulse voltammetry (DPV), a linear calibration range of concentrations between 5.08 X 10(-8) and 4.06 X 10(-6) M can be cov ered and a detection limit of 1.78 X 10(-8) M (S/N = 3) was found. Whe n a goat anti-human IgG is labelled with colloidal gold, the different ial pulse adsorptive stripping voltammetric method (DPASV) allows the determination of antibodies in a range of concentrations from 2.77 X 1 0(-10) to 1.86 X 10(-8) M (relative standard deviation = 5%). The prop osed method seems to be an excellent analytical approach for the deter mination of any protein or macromolecule which can be labelled with mi croparticles of colloidal gold and offers a potential new path to immu noelectroanalytical assay.