| 其他摘要 | Platinum group elements (PGE), gold and silver together, are called precious metals. Chemical analysis of the precious metals has attracted considerable interest of researchers in many fields, such as petrochemistry, metallurgy, geochemistry, materials science, environmental science, electronics, biology, medicine, etc. in this thesis, one of Chinese reference materials, GPt-5, was used to evaluate analytical methods applied. PGE were enriched by anion exchange resin and Te coprecipitation respectively, and the optimal experimental factors and mechanisms were studied. Samples were digested by alkali fusion, and acid leaching prior to alkali fusion respectively, and some modifications were made. Based on the work above, a method was presented for determination of PGE with inductively coupled plasma-mass spectrometer (ICP-MS), which provides a way of quantitative analysis of PGE in geochemical samples, and a good basis for further work on PGE analysis in future. The conclusions of the thesis are as follows: 1. Te coprecipitation was widely applied to enrich trace or ultra-trace level PGE because of its excellent recoveries, wonderful separation efficiencies for PGE from. the base metals, and convenient handling. 2. Anion exchange resin can strongly adsorb Au, Pt, Pd, and Os, except for Ru, especially for Rh, A modified method can elevate the adsorption efficiencies of Ru and Rh, by adding SnCl2 in sample solution. 3. Alkali fusion has several advantages that are (1) 'easy attack of the; refractory samples and PGE minerals; (2) simple handling; (3) low cost; (4) better accuracy of Ru analysis with a modified alkali fusion, nafriely, sarriple and flux added in sequence while analyses of Rh, Pd, Ir, Pt weren't affected. Acid leachirig-alkali fusion is suitable to large samples and PGE minerals that are difficult to be digested completely. The analyses of Au, Pt and Pd were better than those of Ru, especially of Ir, which were lower than the certified values. Moreover, it was more difficultly handled than alkali fusion, 4. ICP-MS can determine PGE rapidly and precisely. Rh and Au are usually determined with internal calibration, while Pt, Pd, Ru and Ir are measured with isotope dilution. 5. Through Te coprecipitation, the precious metals are converted to the products that can be dissolved by concentrated nitric acid and aqua regia. Most of Au is changed to simple element, and Pt and Pd are changed to their tellurides. Further research is needed for other PGE during Te coprecipitation. |
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