富钴结壳铂族元素超细标准物质的研制

Preparation and Study of Two Seamount Co-rich Crust PGEs Ultra-fine Reference Materials:MCPt-1 and MCPt-2

2个富钴结壳铂族元素(PGEs)标准物质MCPt-1和MCPt-2的原样分别由中国和俄罗斯取自中太平洋海山和西太平洋麦哲伦海山区。样品经风干、选配,先经球磨制备成74μm(200目)粉体样品,再用气流磨将其进一步加工成具有超细粒度的均匀样品。采用激光粒度仪检测样品的粒度分布,其平均粒度分别为1.8和1.5μm(约2 000目)。采用高精度的X射线荧光光谱法(XRF)和电子探针方法分别检验了6个主、次元素在mg和μg取样量水平上的均匀性,用LA-ICP-MS检验了包括Pt在内的40多个痕量元素在μg量水平上的均匀性。样品采用锍镍火试金和Carius管预富集和酸溶消解,除Rh外均采用同位素稀释电感耦合等离子体质谱测定(ID-ICP-MS),确定了MCPt-1和MCPt-2中6个铂族元素的标准值;采用XRF和ICP-AES、ICP-MS方法相结合给出了62个主、次和痕量元素的信息值。最小取样量分别为1 g(测定PGEs)和2mg(测定其他元素)。

Two Co-rich seamount crust reference materials （MCPt - 1 and MCPt -2 ） for platinum group elements（PGEs） with ultra-fine particle size were prepared. The raw samples of these two ref- erence materials collected from Magellan seamounts in the Western Pacific Ocean and the seamounts in the Central Pacific Ocean, respectively, were ground by a ball mill to -200 mesh powder, then further by a jet mill to ultra-fine homogenous powder. The particle size distributions of the samples were tested by a laser particle analyzer, and the average particle size were 1.8 and I. 5 μm （ about 2 000 mesh）, respectively. The homogeneities of six major and minor elements in these two materials were tested using mg levels of sampling mass by high-precision wavelength dispersive X-ray： fluorescence（WD-XRF） and μg level of sampling mass by electron probe micro-analyzer（ EPMA）, respectively. The homogeneities of more than 40 trace elements, including Pt, were tested using μg levels of sampling mass by laser ablation inductively coupled plasma mass spectrometry （ LA - ICP -MS）. PGEs in the sample were preconcentrated with the nickel sulphide fire assay and digested with the Carius tube technique. Except for Rh, the elements were determined by isotope dilution（ID） - ICP - MS. The certified values of 6 PGE （ Pt, Pd, Rh, Ir, Os and Ru） in MCPt - 1, and MCPt - 2 were obtained, and the information values of 62 major, minor and trace elements were obtained by XRF, ICP - AES and ICP - MS, respectively. The minimum sampling mass for the determination of PGEs was 1 g, while that for the determination of the other elements was 2 mg.