Microwave-assisted digestion procedure for the determination of palladium in road dust

The present publication describes a microwave-assisted digestion procedure for the subsequent trace and ultra-trace analysis of palladium in road dust of varying origin. Digestion reagents are nitric acid, hydrogen peroxide and hydrofluoric acid. Boric acid is used as masking agent for fluoride ions to avoid removal of excess hydrofluoric acid by vaporization. After the three-step digestion procedure, a colorless and residue-free solution is obtained in which the determination of palladium can be directly performed using a recently developed highly selective on-line pre-concentration system, coupled with graphite furnace atomic absorption spectrometry (GF-AAS). Dust samples of varying origin (tunnel dust, road dust, filter dust from Frankfurt, Munich and Japan) and sampling dates (1987-2001) were investigated and characterized in detail with respect to matrix composition and palladium content. Validation of the analytical results was performed by recovery experiments.