Rapid derivative spectrophotometric method for the determination of platinum in Pt-Ru/C catalyst using iodide media

A rapid spectrophotometric method for the determination of platinum in 20% Pt-Ru (Pt:Ru (1:1)) carbon-supported catalyst has been developed. The sampl es of catalyst (0.85 - 12.60 mg) have been digested 1) in aqua regia after preliminary separation of carbon by burning or 2) directly in aqua regia in the presence of carbon. The detection of platinum was carried out in the o btained solutions after conversion of the metal into the iodide complex. Th e interfering effect of ruthenium on the detection of platinum was eliminat ed by the use of derivative spectrophotometry. Platinum was selectively det ermined by numerical calculation of the 4th-order-derivative absorption spe ctrum of the mixture of iodide complexes of both metals.