Determination of eight lanthanides in apatites by ICP-AES, XRF, and NAA

In the present work eight rare-earth elements (REEs), Hf, and Th were determined in eight apatite samples from San Luis, Argentina. The determinations were carried out by three methods: inductively coupled argon plasma atomic emission spectrometry (ICP-AES), neutron activation analysis (NAA), and X-ray fluorescence spectrometry (XRF). A new support for a small amount of sample was employed in the determination of La, Ce, and Nd by using XRF technique. The same procedure has proved reliable for the determination of major elements by using small amounts of apatite samples. For the ICP-AES determination, a group separation of the REEs from accompanying elements was required. This was achieved by ion- exchange chromatography and sequential acid elution. For the determination by NAA, a nondestructive instrumental technique (thermal neutron activation) was applied. Conditions of irradiation, decay, and measurements for the determination are described. Good correlation is obtained by these three methods.