Synopsis : Evaluation of trace elements in a pure iron and a pure aluminum was performed. The definitive analysis methods of steels and aluminums such as gravity , titrimetry and coulometry are applicable only for high concentration range of elements. In order to develop the definitive methods for low concentration ranges, a study group with national laboratories and steel maker laboratories was organized. The round robin tests showed that the found value by ID-ICP-MS (Isotope Dilution

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... ly Coupled Plasma Mass Spectrometry) have good accuracy and good coincidence with the certified values. The found values by ICP-MS have good coincidence with certified values and/or with the found values by NAA (Neutron Activation Analysis). Trace elements less than 1 ppm could be determined by ICP-MS, however the precision should be improved by standardizing the method. The found values by both ID-ICP-MS and ICP-MS have good repeatability. Oxygen in pure iron was evaluated by round robin test using the inert gas fusion method and CPAA (Charged Particle Activation Analysis) method. Evaluation of surface-oxygen at pure iron was investigated.