A routine method for the determination of low caesium-137 activities in biological samples

Abstract

A routine method for the determination of low fall-out activities of caesium-137 in biological materials is described. Radiocaesium is extracted by adsorption on ammonium molybdophosphate. The usual radiochemical purification of the alkaline ammonium molybdophosphate solution by anion exchange is omitted and caesium precipitated directly with bismuth tri-iodide in the presence of citric acid as complexing agent. A caesium chloroplatinate source is prepared for β-counting.