Abstract
A new spectroelectroanalytical method for the simultaneous determination of iron and copper is presented in terms of the spectroelectrochemical properties of complexes of iron and copper with 2, 2′-bipyridine. By using long optical pathlength thin-layer cells, the differences in the absorbance after complete potential-controlled redox reactions of the two complexes (ΔA) were proportional to the investigated concentration over ranges from 2×10-7M to 5×10-5M for iron and from 4×10-7M to 1×10-4M for copper, respectively. The proposed method offers a higher selectivity than conventional spectrophotometry. In addition, a preconcentration proceudre for copper was taken in 0.2M NH3•H2O-NH4Cl for 1min; the deposited copper was then dissolved into a solution containing 2, 2′-bipyridine as a chromogenic reagent; ΔA, recorded as before, was used as the analytical signal to determine trace copper. The apparent molar absorptivity obtained was ca. 6times that without electrodeposition. Iron and copper in aluminum alloys and pig serum were satisfactorily determined by the proposed methods.
