Automated extraction chromatographic separations of actinides using separation-optimized sequential injection techniques

Abstract

A sequential injection (SI) separation system has been developed for automated analytical separations of actinides using an actinide specific extraction chromatographic material (TRU-resin, Eichrom Industries, Inc., USA). On-line liquid scintillation counting was used to observe eluting species during method development, and fraction collection and alpha energy analysis were used for quantification. Several procedures for individual and group actinide elution are demonstrated and discussed, including elution of actinides as a single group; elution as groups based on valence state; selective separation of Pu using on-column redox chemistry; selective separation of Th; and various sequential actinide elution schemes. Eluent solution compositions and reagent chemistries were investigated with regard to elution peak shapes, selectivity, recoveries, carryover, and suitability for rapid automated procedures. The SI separation methods described serve as the basis for an automated actinide separation work station. An automated actinide separation procedure has been applied towards the analysis of Am, Cm, and Pu isotopes in three types of aged nuclear waste samples. Results from automated analytical separations followed by quantification by alpha spectroscopy were in good agreement with results obtained using manual separation techniques.