Thorium determination by liquid scintillation counting using an extractive cocktail

A simple procedure was developed for the determination of thorium in excretion samples for evaluating Th intakes. After coprecipitation and purification of Th by extraction into an organic phase and backextraction with HCl, the solution was taken to dryness and the residue dissolved in dilute sulfuric acid. Then, Th was extracted into a scintillation cocktail and measured by liquid scintillation counting. Alpha/beta separation was achieved through pulse shape analysis. The beta-emitting Th-234 was used to determine the chemical yield. The lower limit of detection was about 90 ng or 0.3 mBq per sample, comparable to alpha-spectrometry. Copyright (C) 1996 Elsevier Science Ltd.