| The trace precious metals in ores were collected by minified lead fire assay using 5mg Te as protective agent and cupellation retain lead of about 50 mg. The lead alloy was first dissolved in (1+1)HNO3, and then added HCl to form aqua regia to enhance dissolution capability. The lead matrix was separated as PbCl2 precipitate to eliminate interference in the following ICP-MS measurements. The relative standard deviations(n=6) of national standard materials were 4.6%, 8.7%, 4.5%, 9.2%, 6.1% and 5.8% for Au, Pt, Pd, Rh, Ir and Ru, respectively. The determination results of national standard materials and black shale samples were consistent with the recommended value. |
