Neutron activation determination of lanthanum in praseodymium oxide near the detection limit. Comparison of various procedures

Trace amounts of lanthanum in spectrally pure praseodymium oxide have been determined by four independent methods: (1) non-destructive Ge(Li) spectrometry, (2) spectrometry of slow γ-γ coincidences, (3) radiochemical separation of¹⁴⁰La from macro amounts of¹⁴²Pr and other interfering activities (mainly^192,194Ir and^152,154Eu) with∼100% yield, by several ion-exchange steps followed by NaI(Tl) spectrometry, (4) method of standard additions using the same procedure as in method (3). Near the detection limit only the two last methods gave accurate results.