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DETERMINATION OF ENVIRONMENTAL PLATINUM POLLUTION BY INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

AUTHOR/S: ST. PALESSKIY, I. NIKOLAEVA, O. KOZMENKO
Sunday 1 August 2010 by Libadmin2010

10th International Multidisciplinary Scientific GeoConference - SGEM2010, www.sgem.org, SGEM2010 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 20-26, 2010, Vol. 2, 461-466 pp

ABSTRACT

The accurate determination of the platinum group elements (PGEs) in environmental
samples has become a particularly important in the past few years with the introduction
of new legislation regulating the fitting of catalytic converters to petrol vehicles [1]. The
emission of PGEs autocatalysts represents a potentially, highly mobile source of
environmental contamination. Pt, Pd and Rh from catalyst degradation are deposited
along roadways. Although inert in metallic form, platinum salts pose a real health risk.

This paper reports a simple analytical procedure for PGEs determination in geological
and environmental samples using microwave acid digestion, separation of the PGEs by
cation-exchange chromatography and analysis by isotope dilution inductively coupled
plasma mass-spectrometry (ID-ICP-MS). Geological reference materials with lowabundance
of PGEs were weighted into teflon vessels with spikes of PGEs. Acid
digestion of these samples was carried out in the mixture of sub-boiled concentrated
HCl and HNO3 (1:3) under the pressure (20 bar) and the temperature (200ºC) in
hermetic teflon vessels of microwave accelerated reactive system MARS-5. After full
spike-sample equilibration during sample digestion the obtained solutions were
centrifuged to remove the solid residue. Cation exchange columns filled with Dowex
AG50Wx8 resin (200-400 mesh) have been applied for PGE separation using 0.6M HCl
as the mobile phase. Elimination of such cations as Zr and Hf decreases spectral
interferences on PGE peaks in ICP-MS spectra. All ICP-MS isotopic analyses of spikes
and spike-sample mixtures were performed by high resolution ICP mass-spectrometer
ELEMENT Finnigan MAT with ultrasonic nebuliser U-5000AT+. Uncertainty of
isotopic ratio determination was about 0.2%. Concentrations of all elements were
calculated with the known ID formula. 195Pt was used as the internal standard to
calculate the abundances of monoisotope element Rh. Average total procedural blanks
were 10-20 pg for all elements. The obtained PGEs concentrations in low-abundance
reference materials – GP-13, UBN-1 and W-1 are compared with available data. The
new ID-ICP-MS data are in good agreement with previously published values of PGEs
in low-abundance reference materials.

The concentrations of PGEs in environmental samples (road-side dusts and soil from
Novosibirsk, Russia) were determined using proposed analytical procedure.

Keywords: environmental samples, platinum, palladium, rhodium, inductively coupled plasma mass-spectrometry, isotope dilution, catalytic converters