Simultaneous Spectrophotometric Determination of Iron, Cobalt and Copper by Partial Least-Squares Calibration Method in Micellar Medium

Iron, cobalt and copper are metals, which appear together in many real samples, both natural and artificial. Recently a classical univariate micellar colorimetric method has been developed for determination of these metal ions. The organized molecular assemblies such as micelles are used in spectroscopic measurements due to their possible effects on the systems of interest. The ability of micellar systems to solublize slightly insoluble or even very insoluble complexes and/or ligands has been used to enhance the analytical merit of the given methods. The ability of micelles to solublize complexes in aqueous solutions can eliminate the need for non-aqueous extraction step in a given analysis. The simultaneous determination of Fe, Co and Cu was carried out as 1-nitroso-2-naphtolcomplexes in presence of aqueous solution of nonionic surfactant of Triton-X100. A partial least-squares multivariate calibration method for the analysis of ternary mixtures of Fe, Co and Cu was developed. For individual determinations, molar absorptivities and the limit of detection were obtained, respectively. The total relative standard error for applying the method on synthetic samples was 2.02%. The proposed method was also successfully when applied to the determination of Fe, Co and Cu in several synthetic alloy solutions.