Spectrophotometric determination of mixtures of iron(III) and manganese(II) by complexation with 3-indolylacetohydroxamic acid and principal component regression multivariate calibration

Abstract

The use of principal component regression (PCR) for the multicomponent analysis of complex mixtures offers considerable advantages over conventional multiple linear regression in ultraviolet–visible spectrophotometry. PCR provides a sensitive and accurate technique for the analysis of complex mixtures with severely overlapping spectra. A method for the simultaneous determination of Fe³⁺ and Mn²⁺ is described based on the measurement of the absorbance of the complexes formed by both ions with 3-indolylacetohydroxamic acid. The complexes were extracted with a solution of methyltrioctylammonium chloride in toluene. The application of the PCR multivariate calibration method allowed the resolution of the overlapping of the spectra of the respective Fe³⁺ and Mn²⁺ complexes with the hydroxamic acid derivative. The method was applied satisfactorily to the determination of Fe³⁺ and Mn²⁺ in several multivitamin preparations.