Determination of Chemical Species of Platinum, Palladium and Rhodium in Roadside Surface Soil with a Modified BCR Method

Pt, Pd and Rh as the main ingredients in automotive catalytic converters, effectively reduce automobile exhaust pollution, but continuously emit into the environment. The migration, conversion and circulation in groundwater of these elements potentially generate new environmental pollution problems. In this paper the improved BCR sequential extraction method was applied to the chemical species analysis of platinum group elements (PGEs). Combined with the nature of the PGEs, the chemical species of Pt, Pd and Rh in roadside surface soil were divided into four fractions: acid soluble, reducible, oxidisable and residual. The original BCR leaching conditions were optimized and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) was used to measure various chemical species of Pt, Pd and Rh. The precisions and detection limits of all the chemical species all met the monitoring requirements of the testing quality management for geological laboratories (DZ/T 0130—2006). All the recoveries were from 95.3% to 110.0%, which indicated the established method had good accuracy and reproducibility. The analysis results for actual samples of the surface soil samples on both sides of the road demonstrated the contents of PGEs in non-residual fraction were in order as Pd(57.23%-58.03%)>Rh(22.64%-25.80%)>Pt(17.91%-20.57%) and the probabilities for PGEs entering the biosphere were Pd> Rh> Pt.