Radiochemical neutron activation analysis determination of rare earth elements in geological materials with ppb sensitivity

Rare earth elements are determined, with ppb sensitivity, by radiochemical activation analysis using a fusion dissolution process and a quantitative group separation scheme, followed by radioassaying. Spectral interference is avoided, or corrected for, by repeating the counting operation with a delay of four to six weeks. This allows for the decay of shorter lived interfering isotopes such as¹⁵⁵Eu on¹⁶⁰Tb and¹⁷⁵Yb on¹⁴¹Ce. The scheme is rapid, sensitive and uses standard radiochemical laboratory facilities and counters. It has been applied to a wide range of rocks and minerals and data for eleven rare earths (La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Tm, Yb and Lu) is presented here and compared with literature values.