Determination of platinum and ruthenium in Pt and Pt-Ru catalysts with carbon support by direct and derivative spectrophotometry

Platinum and ruthenium in carbon supported Pt and Pt-Ru catalysts were dete rmined by direct and derivative spectrophotometric methods. Complexes of pl atinum and ruthenium with SnCl3- ligands (tin(II) chloride in HCl) were use d to determine both metals in solutions obtained after digestion of the sam ples of the catalysts. Platinum in the Pt/C catalyst can be determined in s olutions obtained by digestion of the samples in aqua regia. Derivative spe ctrophotometry was used to determine both metals in the presence of each ot her in solutions obtained after digestion of samples of the Pt-Ru/C catalys t in the mixture of HCl + HNO3 (6:1). The first derivative at 377 nm ('zero -crossing' point of ruthenium) and the second-derivative values at 495 nm ( 'zero-crossing' point of platinum) were used to estimate the concentration of platinum and ruthenium, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.