Preparation of Geochemical Standard Reference Black Shale Samples for Trace Platinum Group Element Analysis

A geochemical certified reference black shale sample for trace platinum group elements (PGEs) analysis was prepared. The original black shale sample was collected from Huangjiawan in Guizhou province. The sample was prepared to grain size of 74 μm through the primary crushing and fine grinding. The samples which had passed through the granularity examination, the homogeneity examination and the stable examination were distributed to 11 national authority geological laboratories for six PGEs (Pt, Pd, Ru, Os, Rh, Ir) analysis based on the basic requirements of ISO GUIDE 34, ISO GUIDE 35 and 《The National Technical Specifications for Preparation of Primary Standard Reference Materials》. Six analytical methods with different principles were used for the certification. In the certification, each set of the data from the laboratories was regarded as the smallest statistical unit. Grubbs criteria and Dixon's method were used for analytical data processing and Shapiro-Wilk method was used for testing the normality of the element distribution. The results from the tests showed that 100% of certified values of six PGEs presented the normal distribution or near-normal distribution and were in accordance with the quality requirements of the standards.