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Abstract
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Evolutionary factor analysis (EFA) and rank annihilation factor analysis (RAFA) were applied to resolve the two-way equilibrium spectrophotometric data for the determination of stability constants ofthe complexes of 1,8-bis(o-aminophenoxy)-3,6-dioxaoctane (BOAPD) with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+ and Hg2+ ions. The number of component species was determined by factor analysis of the absorbance data and then a hard model between the analytical concentrations ofthe ligand and metal ions, the equilibrium concentrations of all species present and the corresponding equilibrium constants was written. By knowing the equilibrium constants, the equilibrium concentrations of the species will be calculated at each metal to ligand mole ratio. The values of equilibrium constants were varied iteratively and, at each iteration, the ligand's information (i.e., the equilibrium concentration and spectral information) were annihilated from the original data matrix until the rank of the original data matrix was reduced by one. The results revealed that ligand forms ML complexes with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ and a ML2 adduct with Hg2+ ion. The equilibrium constants, the concentration and spectrum profiles of each complexed species were then calculated. The residual standard deviation (RSD) ofthe residual matrix after bilinearization ofthe background matrix is regarded as the evaluation function.
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