DETERMINATION OF IRON AND COPPER BY SPECTROELECTROCHEMISTRY

A new spectroelectroanalytical method for the simultaneous determinati on of iron and copper is presented in terms of the spectroelectrochemi cal properties of complexes of iron and copper with 2,2'-bipyridine. B y using long optical pathlength thin-layer cells, the differences in t he absorbance after complete potential-controlled redox reactions of t he two complexes (Delta A) were proportional to the investigated conce ntration over ranges from 2x10(-7) M to 5x10(-5) M for iron and from 4 x10(-7) M to 1x10(-4) M for copper, respectively. The proposed method offers a higher selectivity than conventional spectrophotometry. In ad dition, a preconcentration proceudre for copper was taken in 0.2 M NH3 . H2O-NH4Cl for 1 min; the deposited copper was then dissolved into a solution containing 2,2'-bipyridine as a chromogenic reagent; Delta A , recorded as before, was used as the analytical signal to determine t race copper. The apparent molar absorptivity obtained was ca. 6 times that without electrodeposition. Iron and copper in aluminum alloys and pig serum were satisfactorily determined by the proposed methods.