DETERMINATION OF RARE-EARTH ELEMENTS IN THE BIOLOGICAL REFERENCE MATERIALS PINE NEEDLES AND SPRUCE NEEDLES BY NEUTRON-ACTIVATION ANALYSIS

Instrumental neutron activation analysis was applied to determine La C e, Nd, Sm, Eu, Tb, Yb, Lu and Sc in two biological reference materials : NIST 1575 Pine Needles and BCR-CRM 101 Spruce Needles. The purpose w as to contribute to the reference data for these two reference materia ls. The results were obtained with a good precision (relative standard deviations less than 15%). For the Pine Needles reference material th ere are already some proposed values and our results showed, in genera l, a good agreement with the data published. The contribution of urani um fission products to La, Ce, Nd and Sm was evaluated and considered in the determination of these elements. Interferences in the determina tion of rare earth elements in biological materials are also discussed .