Evaluation of methods for the radiometric measurement of americium-241 in environmental samples

The presence of substantial amounts of manganese in a series of soil samples (about 7000 p.p.m.) led to the failure of an established method for the determination of 241Am in soils and environmental samples. A review of alternative approaches led to the development and optimisation of a more robust technique. After acid dissolution, solvent extraction of iron and anion-exchange separation of plutonium isotopes, manganese is removed by cation exchange. Rare earth elements and americium are coprecipitated on Fe(OH)3, separated by anion exchange in nitric acid-methanol and the remaining impurities removed by anion exchange in nitric acid. Chemical yields are greatly improved and analysis of reference materials gives satisfactory results.