A neutron activation method is described for the analysis of small concentrations of Cu, Cd, Mn, Co, Cr and Zn contaminants
in thorium and zirconium compounds used for telecommunication and reactor techniques. The thorium matrix is separated from
the contaminants by pre-irradiation paper chromatography and the233Pa is isolated after irradiation by extraction into methyl isobutyl ketone and precipitation with cupferron. For the analysis
of the contaminant in zirconium compounds only precipitation with cupferron is used after irradiation. The individual impurities
are determined by γ-spectrometry following separation.