A new method to isolate americium from environmental samples using Diphonix resins

The Aquatic Radioactivity Laboratory of Ciemat has been performing transuranic analyses in different types of matrices such as soils, marine sediments and biota for a good number of years. Analysing americium in large size/volume samples by employing ionic-exchange resins becomes a long and tedious process, usually resulting in low chemical recoveries. A new procedure to isolate americium from environmental samples has been developed by concentrating americium in a Diphonix resin. This resin is then destroyed by calcination at 550°C and further digestion with HNO3 and H2O2 in a microwave oven programmed with increasing pressure stages, reaching 175 psi. Isolation is completed with TRU-Spec and TEVA-Spec columns. Americum is finally quantified by high resolution alpha spectrometry. Analyses carried out with various reference IAEA materials proved that this new method produces higher radiochemical yields, thus allowing treatment of smaller environmental samples.