| Abstrakt: |
A fast and simple method for the direct determination of low concentrations of Os, Ir, Ru, Pt and Re from the same sample aliquot has been developed. It exploits the superior mass resolution capabilities of a double focussing sector field mass spectrometer (Finnigan MAT Element), in combination with a highly sensitive, high TDS tolerant teflon® Microflow nebulizer. Samples are spiked with an Os isotopic tracer, and digested in inverse aqua regia in sealed Carius tubes for 24 hours at 240 °C. Osmium is subsequently separated from the matrix (which contains the other PGEs) in a previously developed solvent extraction step, and measured in low resolution mode. The remaining sample solution is dried, redissolved in 2% HCl and analyzed directly for Ir, Ru, Pt and Re using the method of standard addition, in high resolution mode. Procedural blanks are <0.009 ppb for all PGEs except Pt (~0.046 ppb) and Rh (~0.0143 ppb). Instrumental detection limits based on the 3σ criterion for background are 0.0009 ppb for Re, 0.0048 ppb for Os, 0.002 ppb for Ru, and 0.003 and 0.01 ppb for Ir and Pt, respectively. The accuracy of the analytical method has been verified by comparing the results obtained in this study for three PGE reference materials (komatiite WITS1, komatiite KAL1, and peridotite GP13) with those reported in the literature. |
