Microchemical Journal 73 (2002) 317–324 0026-265X/02/$ - see front matter  2002 Elsevier Science B.V. All rights reserved. PII:S0026-265X Ž 02 . 00103-0 Simultaneous determination of iron and ruthenium by preconcentration on sulfopropyl sephadex cation exchanger M. Ines Toral *, Carolina Paipa , Jessica Narvaez , Pablo Richter a, a a b,c ´ ´ Laboratory of Analytical Chemistry, Department of Chemistry, Faculty of Sciences, University of Chile, P.O. Box 653, Santiago, a Chile National Environmental Center (CENMA), University of Chile, Av. Larrain 9975, La Reina, Santiago, Chile b Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, c P.O. Box 233, Santiago, Chile Received 1 April 2002; accepted 26 June 2002 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 ClCOOHyCH ClCOONa (pHs3.0). The formation 2 2 of the complexes and their retention on a cationic resin SP-Sephadex C25 were integrated in one step at 90 8C, 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 and 1.79 ng ml for ruthenium and y1 y1 0.41 ng ml and 1.38 ng ml for iron. The proposed method was applied to the determination of both analytes in y1 y1 synthetic mixtures.  2002 Elsevier Science B.V. All rights reserved. Keywords: Iron and ruthenium determination; Preconcentration in solid phase 1. Introduction Different studies have been carried out regarding the preparation of materials containing Fe–Ru. Due to their electrochemical and thermoelectric properties w1–6x, such types of materials have shown potential catalytic, analytical and technolog- *Corresponding author. Tel.: q56-2-6787262; fax: q56-2- 2713888. E-mail address: analitic@uchile.cl (M.I. Toral). ical applications. For example, Fe–Ru catalysts have been used for NH synthesis w1x, pyridine 3 hydrodenitrogenation w2x, water gas shift reaction w3x, and n-butanol conversion w4x. The use of these kinds of catalysts in industrial processes could cause iron and ruthenium contamination in aquatic systems which necessitates the development of analytical methods for the simultaneous determi- nation of these metals in waters at ultra-trace levels.