Separation and preconcentration of La from monazite, followed by determination using nondestructive γ-ray spectrometry

A method was developed for separation, preconcentration, and determination of La by its radioactive isotope ¹³⁸La using an HPGe detector. The method was checked by comparison with ICP-MS. The detection limit (minimum detection activity) is 1.46 and 1.52 Bq kg^?1 at 788.4 and 1435.8 keV lines, respectively. The Th(IV) and U(VI) are separated by precipitation. To separate Ac(III), it is extracted jointly with REEs from 0.1 M HNO₃ with HDEHP and then stripped with 0.2 M HNO₃, with REEs remaining in the organic phase. Lanthanum in a mixture with REEs is determined by ??-ray spectrometry.