Analytical Determination and Bio-Monitoring of Platinum Group Elements in Roadside Grass Using Microwave Assisted Digestion and Electrothermal Atomic Absorption Spectrometry

Abstract

The analytical conditions that enable the determination of traffic related platinum group elements (PGEs) in roadside grass using microwave digestion and electrothermal atomic absorption spectrometry were evaluated as an alternative to the biomonitoring of traffic related PGEs and Pb levels in urban areas. To optimize the analytical conditions and account for matrix effects that could import error in the analysis, method optimization was based on matrix simulation through analyte recovery from spiked unpolluted samples against a matrix blank. A mixture of nitric and hydrofluoric acid under progressively increasing microwave irradiation was optimized to afford the quantitative extraction of platinum group elements from plant matrix. Due to the low levels of platinum group elements in real samples, preconcentration was accomplished using sample evaporation followed by dissolution in dilute nitric acid prior to deliverance to the atomic detector. Quantitation limits below 1 ng g⁻¹ for Pd and Rh and lower than 2 ng g⁻¹ for Pt, were accomplished, enabling the monitoring of platinum group elements bioaccumulation in roadside grass with satisfactory recoveries, as determined from the analysis of spiked samples. The results from method application in an annual monitoring survey of PGEs and Pb levels in urban flora and other roadside media are presented and discussed.

Keywords:

• Atomic absorption spectrometry
• Microwave digestion
• Platinum group elements
• Roadside grass
• Urban pollution

Acknowledgments

This paper is part of a special issue organized by Dr. Nikolaos Thomaidis and Dr. Antony C. Calokerinos from research presented at the Aegean Analytical Chemistry Days Conference in Lesvos, Greece on 29 September–3 October 2010.

Notes

Each value represents the average of nine specimens from the same sampling grid. Concentrations are the average of triplicate measurements (n = 3) and are expressed as ng g⁻¹ ± SD for Pt, Pd, and Rh and as µg g⁻¹ ± SD for Pb.