Pre-concentration of actinide elements from soils and large volume water samples using extraction chromatography

The analysis of environmental samples for low levels of U, Pu, Am and other actinide elements is often hampered by sample-dependent problems involving the composition and/or mineralogy of specific samples. While relatively small samples (1-2 g of soil or 1-2 l of water) are required to reach the extremely low detection limits occasionally mandated for environmental monitoring. One approach to avoid the troublesome and often inexplicable problems collectively referred to as 'matrix effects' is to pre-concentrate actinides into a common form that would then behave uniformly and predictably during a subsequent separation scheme. Recently, a new extraction chromatographic resin based on diphosphonate chemistry was developed at Argonne National Laboratory. This resin commercialized as Eichrom's Actinide Resin, exhibits extremely high affinity for actinide elements even in the presence of high concentrations of salts. We have measured the uptake of actinides by the DipexR extractant from natural waters and natural matrix soil standards. Water samples have been analyzed for gross α-activities and gave results that compared favorably to the traditional approach. In addition, we have obtained good recoveries and excellent separations for soil samples as judged by resolution on the α-spectra and the complete absence of interfering energies. (author)