Determination of platinum and rhodium in dust and plant samples using microwave-assisted sample digestion and ICP-MS

The platinum group elements (PGEs), particularly platinum, palladium and rhodium, are nowadays increasingly emitted into the environment from automotive catalytic converters. Thus, a method for the determination of PGEs (especially platinum and rhodium) in dust and plant samples was developed. The developed method was based on microwave-assisted sample digestion and inductively coupled plasma mass spectrometric (ICP-MS) determination. Spectral interferences in ICP-MS determination were corrected using mathematical correction equations based on signal ratio measurement. In addition, platinum and rhodium concentrations in the digested dust samples were also determined after Te coprecipitation without correction of the interferences. The results for platinum and rhodium in reference materials (NIST SRM 2557, recycled monolith autocatalyst and BCR-723, road dust) were in good agreement with the certified values. Preliminary results for the anthropogenic platinum and rhodium emissions in Oulu, northern Finland, based on dust and plant samples, indicated a common traffic-related source of these metals.