Determination of individual rare earth elements in Vietnamese monazite by radiochemical neutron activation analysis

Radiochemical neutron activation analysis (RNAA) has been applied for determination of rare earth elements (REE) in Vietnamese monazite. The chemical separation procedure used is based on the chromatographic elution of rare earth groups, after the separation of²³³Pa(Th) in irradiated monazite samples by coprecipitation with MnO₂, the rare earth elements were retained by Biorad AG1×8 resin column in 10% 15.4M HNO₃-90% methanol solution. The elution of heavy rare earth (HREE) and middle rare earth (MREE) groups was carried out with 10% 1M HNO₃-90% methanol and 10% 0.05M HNO₃-90% methanol solution, respectively; while the light rare earths (LREE) were eluted from the column by 0.1M HNO₃ solution. The accuracy of the method was checked by the analysis of granodiorite GSP-I and the rare earth values were in good agreement.