Americium and plutonium separation by extraction chromatography for determination by accelerator mass spectrometry

A simple method was developed to separate Pu and Am using single column extraction chromatography employing N,N,N',N'-tetra-n-octyldiglycolamide (DGA) resin. Isotope dilution measurements of Am and Pu were performed using accelerator mass spectrometry (AMS) and alpha spectrometry. For maximum adsorption Pu was stabilized in the tetra valent oxidation state in 8 M HNO3 with 0.05 M NaNO2 before loading the sample onto the resin. Am(III) was adsorbed also onto the resin from concentrated HNO3, and desorbed with 0.1 M HCl while keeping the Pu adsorbed. The on-column reduction of Pu(IV) to Pu(III) with 0.02 M TiCl3 facilitated the complete desorption of Pu. Interferences (e.g. Ca2+, Fe3+) were washed off from the resin bed with excess HNO3. Using NdF3, micro-precipitates of the separated isotopes were prepared for analysis by both AMS and alpha spectrometry. The recovery was 97.7 +/- 5.3% and 95.5 +/- 4.6% for Am-241 and Pu-242 respectively in reagents without a matrix. The recoveries of the same isotopes were 99.1 +/- 6.0 and 96.8 +/- 5.3% respectively in garden soil. The robustness of the method was validated using certified reference materials (IAEA 384 and IAEA 385). The measurements agree with the certified values over a range of about 1-100 Bq kg(-1). The single column separation of Pu and Am saves reagents, separation time, and cost. (c) 2014 Elsevier B. V. All rights reserved.