FLOW ELECTROANALYSIS OF METAL ALLOY-FILMS - APPLICATION TO THE COMPOSITIONAL ASSAY OF COPPER-NICKEL-ALLOYS

This article describes a how electroanalysis (FEA) alternative to the atomic absorption spectrometry (AAS) procedure commonly employed for t he compositional assay of Cu-Ni alloy thin films. Nine alloy film samp les were plated on polycrystalline Au foil by varying the deposition p otential and the concentration of Cu2+ ions in the plating bath to aff ord alloys varying in copper content from ca. 10 % to ca. 70 % (by mas s). The FEA technique is based on first chemically stripping the alloy components from the support into the flow stream. The Cu2+ ions are t hen analysed by differential pulse anodic stripping voltammetry (DPASV ) at a thin film mercury electrode. Since these Cu2+ ions interfere wi th nickel analyses by DPASV, they are removed from the flow stream at a ''filter'' cell containing a Hg-coated reticulated vitreous carbon e lectrode. The nickel content of the alloy can then be assayed at the d ownstream detector cell. The data from this twin-cell FEA procedure ar e compared with those obtained on the same alloy samples by the standa rd AAS technique.