The major and trace element contents in three iron-based ore reference materials were investigated using two methods of k0-based neutron activation analysis (k0-NAA): instrumental (k0-INAA) and radiochemical (k0-RNAA). To avoid interferences from iron in the determination of elements present at trace levels, a method using radiochemical separation was applied (k0-RNAA). Determination of the investigated elements by k0-RNAA in the aqueous phase from hydrochloric acid solution was performed after extraction of iron by diisopropyl ether (DIPE). It was found that Fe elimination lowered the limit of detection for some elements, thus enabling the determination of their content. The distribution of 39 elements (with intermediate/medium and long half-life radionuclides) present in the studied materials after Fe removal was investigated.