Determination of light rare earth elements in apatite by x-ray fluorescence spectrometry after anion exchange extraction

The results of an investigation, the purpose of which was to study the feasibility of analysis of La, Ce, Pr, and Nd in apatite minerals, utilizing x-ray fluorescence spectrometry (XRF), are discussed. After sample dissolution in HNO3, rare-earth elements (REEs) are separated by a mixed solvent anion exchange using the batch extraction technique. The anion exchanger employed is the strongly basic resin Dowex 1X8, 100 to 200 mesh (nitrate form). REEs are fixed on the resin from a medium consisting of 95% CH3OH-5% 7 M HNO3 (v/v). The dried resin is uniformly spread over a disk of self-adhesive foil backed with a cellulose support. The thin resin film formed is then used for XRF analysis. Synthetic standards prepared following the same procedure are employed for calibration. Analytical results of two apatite samples are presented. Good correlation is obtained between XRF and neutron activation analysis data. Limits of detection, precision, and accuracy of the results are discussed