doi:

DOI: 10.3724/SP.J.1084.2013.00414

Chinese Journal of Polar Research (极地研究) 2013/25:4 PP.414-424

SEVERAL IMPORTANT FACTORS CONCERNING THE CHEMICAL SEPARATION OF RE-OS ISOTOPES IN METEORITES


Abstract:
Some important conditions are discussed in this paper for the high-precision measurement of Re and Os in meteorites by means of the isotope dilution technique. We have measured the Re-Os system in whole rock samples from six ordinary chondrites and two iron meteorites. The result shows that 1 mol/L HCl can be used to remove rust from a metal surface. Additionally, a high digestion temperature is necessary for the digestion of meteorites. Under normal conditions, only about 30% of the Os in the meteorite samples can be dissolved out. However, even though microdistillation is not necessary after Re-Os separation by means of distillation technique, this secondary purification method can improve the stability and accuracy of the signal. In contrast with samples dissolved by HNO3, the intensity of Os in samples dissolved by reverse aqua regia is far stronger. When the concentration and quantity of spikes are adequate and there is a perfect equilibrium between samples and spikes, we generally can attain good data that are consistent with references. The minimum quantity of ordinary chondrites is 0.1 to 0.3 g or the absolute abundance of Os is 100 ng during digestion, with low blank levels (Re 4 to 77 pg, Os 0.5 pg to 2 ng) when the standard deviation of 187Os/188Os can be limited to ±4×10-6 (n=120, 2 SE).

Key words:meteorite, Re-Os, isotope dilution technique, TIMS

ReleaseDate:2014-07-21 16:59:42



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