Simultaneous spectrophotometric determination of copper(II) and nickel(II) as complexes with sodium diethyldithiocarbamate in an anionic micellar medium using partial least-squares regression

A spectrophotometric method for the simultaneous determination of copper and nickel by the use of diethyldithiocarbamate (DDTC) as a chelating agent in the presence of aqueous anionic micellar medium of sodium dodecyl sulfate (SDS) was developed. The presence of micellar systems allow one to eliminate the solvent extraction step necessary for the determination of metal-DDTC complexes in the absence of micelles. This reduces the cost and toxicity of the method. The influence of chemical variables affecting the analytical reaction was evaluated. A partial least-squares procedure was used to access data obtained from the calibration solutions. The ensuing method was validated by applying it to the analysis of synthetic mixtures over the concentration ranges 0-286 mu mol Cu/ml and 0-619 mu mol Ni/ml. The relative errors in determinations were less than 5% in most cases. The proposed method was applied to the determination of Cu and Ni in metal alloys. (C) 1999 Academic Press.