Determination of Rh, Pd and Pt in environmental silica containing matrices: capabilities and limitations of ICP-SFMS

Quantification of three platinum group elements most relevant to environmen tal monitoring, ie. Pt, Rh and Pd, was performed in road dust, exploiting t he high mass resolution capabilities of ICP-SFMS (ELEMENT, Finnigan MAT, Br emen, Germany). Sample preparation,involved complete microwave assisted aci d digestion of the silicate matrix with HNO3-HCl-HF mixtures. A USN6000AT() ultrasonic nebulizer (Cetac Technologies, Omaha, NE, USA) incorporating a membrane desolvation unit was used as the introduction system. For Pt the Hf oxide interference could be eliminated effectively by membrane desolvati on alone. For Ph and Pd, interferences, which could not be eliminated by ma ss resolution, were evaluated carefully by standard addition of the concomi tant ions. It could be shown that no mathematical correction of the result was necessary for Rh, provided that membrane desolvation was employed. Pd i n turn could not be measured interference free with this instrumental set-u p. A mathematical correction procedure was developed for Sr. Concentrations of 63 ng g(-1) Pt, 9 ng g(-1) Ph and 17 ng g(-1) Pd were found in the road dust samples. The limits of detection were 0.4 ng g(-1) for Pt, 0.1 ng g(- 1) for Rh and 0.5 for Pd. The overall method precision determined for six s amples ranged from 6% (Pt) to 13% (Pd).