Loss of osmium during fusion of geological materials

Recently a procedure was reported for the determination of noble metals in geological samples in which the sample is exposed to neutron activation followed by fusion with Na2O2 and NaOH. In an examination of this procedure quantitative determinations of the Os present could not be made. In a tracer technique study of the procedure it was determined that Os tends to oxidize to the volatile OsO4 during the fusion/dissolution step. More serious losses occurred however when the dissolved melt was boiled with HNO3 to destroy the peroxide. The effect on the analytical results if total procedural volatilization losses for Os standard samples are different from losses for geological Os samples is considered. (U.S.)