Determination of actinides in environmental materials using extraction chromatography

The determination of actinides at low level in environmental materials has always been a time-consuming and difficult task. The trivalent actinides in particular require lengthy separation methods that often use large amounts of hazardous materials, producing a waste disposal problem. In the last 10 years extraction chromatography (reversed phase partition chromatography) of the actinides has undergone considerable development. The technique uses an inert polymeric support which is impregnated with a selective extractant to form a solid sorbent in the extraction column. Extractants have been developed by Horowitz and co-workers to give very specific adsorption of actinides in the presence of other elements. These resins are now commercially available, making possible their use in routine analysis. The difficulty in applying this technique to environmental sample analysis is that, as the materials are expensive, only small columns are used. This means that preconcentration techniques must be used to allow the sample to be presented to the extraction column in a sufficiently small volume. The preconcentration steps used, must be chosen to lower the concentration of interfering elements to an acceptable level while giving a high yield of the required analyte and not making the method unduly long. This paper describes the methods used in our laboratories and current operating experience of them.