Rare earth element determinations at ultratrace abundance levels in geologic materials

Abstract

The geochemically very important group of rare earth elements (REE) has frequently been analyzed with activation techniques. The importance of easy and quick techniques which are able to provide reliable data at very low abundance levels has been frequently discussed. We present three different methods using activation techniques yielding REE data at very low abundance levels in geologic materials. With proper selection of counting conditions and irradiations it is possible to use pure instrumental neutron activation analysis at ppb abundance levels (depending on the type of the material). A second method involves group separation of the REE's before irradiation, which yields data for all REE's, but is rather time consuming. The best results were obtained with a group separation after activation and several counting cycles, giving data for 8 REE's. This method has the advantage of providing results even in the sub-ppb range.