Determination of Trace Amounts of Platinum, Palladium, Rhodium and Iridium in High Purity Iron by ICP-OES and ICP-MS after Separation by Coprecipitation with Tellurium

Trace amounts of Pt, Pd, Rh and Ir in an iron solution sample were separated by a reductive co-precipitation process using Te and tin(II) chloride, and determined by ICP-OES and ICP-MS. The recovery test of Pt, Pd, Rh and Ir added in the solution sample was carried out after co-precipitation. The recovery of Pt, Pd and Rh added in the solution sample (100 ng each) were almost 100% under the following conditions: the concentration of hydrochloric acid was adjusted to 0.5 mol.l-1, and 2.0 mg Te as a co-precipitant and 2.5 g tin(II) chloride as a reductant were added. The suitable standing time for the co-precipitation was 3 hours. On the other hand, the recovery of Ir was about 90%. After co-precipitation with Te, the detection limits by ICP-OES are 0.085 μg.g-1 for Pt, 0.32 μg.g-1 for Pd, 0.099 μg.g-1 for Rh and 0.094 μg.g-1 for Ir, and those by ICP-MS are 3.9 ng.g-1 for Pt, 5.0 ng.g-1 for Pd, 1.6 ng.g-1 for Rh and 1.0 ng.g-1 for Ir.