Theoretical analysis and determination of the heterogeneous stability constant of copper(II) humic acids complex at chemically modified carbon paste electrode

A theory for determining the heterogeneous stability constant of a metal co mplex system at the surface of a chemically modified carbon paste electrode was developed. The proposed theory has been applied to the studies of a co pper(II)-humic acids (Has) complex system. In an open circuit, copper(II) w as accumulated from a stirred preconcentration medium onto the HAs-CMCPE. T he subsequent electrochemical measurement was performed in a small Volume o f Britron-Robinson (B-R) buffer (pH 3.78). By means of cyclic voltammetry ( CV) and anodic stripping voltammetry (ASV), the determined average heteroge neous stability constant of copper(II)-HAs complex was 4.99 x 10(9).