Analysis of mixtures containing Al(III) and Fe(III) ions as eriochrome cyanine R complexes by partial least squares regression

A spectrophotometric method for simultaneous determination of Fe(III) and Al(III) using Eriochrome Ciyanine R (ECR) as a reagent was developed. The parameters controlling behavior of the system were investigated and optimum conditions were selected. The analytes formed stable complexes with acetate buffered medium at pH 6.0 İn the presence of CTAB and CPC, the absorbance of the Al(III)-ECR and Fe(III)-ECR complexes decreased.Multivariate regression procedures: Multiple linear regression (MLR), Principal component regression (PCR), Principle Components Analysis(PCA), Partial least squares regression (PLS) and Uniquevariation Calibration (UC) are tested as calibration methods for the spectrophotometric determination of the mixtures containing Al(III) and Fe(III) ions. The experimental calibration set was composed of 10 standart solutions in the ranges of 0,20?0,38 ?g/ml of Al(III) and 0,20?0,80 ?g/ml of Fe(III) and the absorption spectra of these solutions were recorded from 400 to 600 nm.The results obtained by the application of the different chemometric calibration methods were compared those obtained by with atomic absorption spectrometry (AAS) method. For Fe(III) ion ; PCR and PLS methods provided better obtained by with AAS method results than those obtained by UC and MLR. For Al(III) metal ion; UC, PCR and PLS provided slightly better obtained by with AAS method results than those obtained by MLR. These methods were applied to simultaneous determination of these metal ions in Portland cement.