Simultaneous determination of iron and ruthenium by preconcentration on sulfopropyl sephadex cation exchanger

Abstract

A new method for the simultaneous determination of iron and ruthenium at ultra-trace levels is proposed. The method is based on the formation of the iron and ruthenium complexes with 2,4,6-tri-(2-pyridil)-1,3,5-triazine (TPTZ) in the presence of hydroxylamine hydrochloride and buffer CH 2ClCOOH/CH 2ClCOONa (pH=3.0). The formation of the complexes and their retention on a cationic resin SP-Sephadex C25 were integrated in one step at 90 °C, with stirring for 90 min. Under these conditions a high preconcentration level was achieved for both analytes. The complexes retained on the solid phase were evaluated by second derivative spectrophotometry. The selected analytical wavelengths were 539.7 and 553.3 nm for the determination of ruthenium and iron, respectively, by using the zero crossing approach. The detection and quantification limits were 0.54 ng ml −1 and 1.79 ng ml −1 for ruthenium and 0.41 ng ml −1 and 1.38 ng ml −1 for iron. The proposed method was applied to the determination of both analytes in synthetic mixtures.