SIMULTANEOUS SPECTROPHOTOMETRIC DETERMINATION OF IRON, COBALT, AND NICKEL BY PARTIAL LEAST SQUARES CALIBRATION METHOD IN MICELLAR MEDIUM

Abstract

The simultaneous determination of Fe, Co and Ni was carried out as 2-aminocyclo-1-pentene dithiocarboxylic acid (ACDA) complexes in the presence of an aqueous solution of cationic surfactant of cetyl trimethylammonium bromide (CTAB). The presence of micellar systems allows one to eliminate the previous solvent extraction step that is necessary for the determination of metal-ACDA complexes in the absence of micelles. This reduces the cost and toxicity of the method. A partial least-squares multivariate calibration method for the analysis of ternary mixtures of Fe, Co and Ni was developed. For individual determinations, molar absorptivities of 8.46 × 10³ (Fe, 650 nm), 4.76 × 10⁴ (Co, 458 nm) and 2.61 × 10⁴ (Ni, 538 nm), were obtained, the limit of detection being 0.11, 0.04 and 0.04 μg/ml, for Fe, Co and Ni, respectively. The total relative standard error for applying the method on 15 synthetic samples in the concentration ranges of 0.2–3.0 μg/ml Fe, 0.05–2 μg/ml Co and 0.05–2.5 μg/ml was 2.02%. The proposed method was also successfully applied to the determination of Fe, Co and Ni in several synthetic alloy solutions.

ACKNOWLEDGMENTS

The authors wish to acknowledge the support of this work by Shiraz University Research Council for the support of this work.