Automation of Extraction Chromatograhic and Ion Exchange Separations for Radiochemical Analysis and Monitoring
Radiochemical analysis, complete with the separation of radionuclides of interest from the sample matrix and from other interfering radionuclides, is often an essential step in the determination of the radiochemical composition of a nuclear sample or process stream. Although some radionuclides can be determined nondestructively by gamma spectroscopy, where the gamma rays penetrate significant distances in condensed media and the gamma ray energies are diagnostic for specific radionuclides, other radionuclides that may be of interest emit only alpha or beta particles. For these, samples must be taken for destructive analysis and radiochemical separations are required. For process monitoring purposes, the radiochemical separation and detection methods must be rapid so that the results will be timely. These results could be obtained by laboratory analysis or by radiochemical process analyzers operating on-line or at-site. In either case, there is a need for automated radiochemical analysis methods to provide speed, throughput, safety, and consistent analytical protocols. Classical methods of separation used during the development of nuclear technologies, namely manual precipitations, solvent extractions, and ion exchange, are slow and labor intensive. Fortunately, the convergence of digital instrumentation for preprogrammed fluid manipulation and the development of new separation materials for column-based isolation of radionuclides has enabled the development of automated radiochemical analysis methodology. The primary means for separating radionuclides in solution are liquid-liquid extraction and ion exchange. These processes are well known and have been reviewed in the past.1 Ion exchange is readily employed in column formats. Liquid-liquid extraction can also be implemented on column formats using solvent-impregnated resins as extraction chromatographic materials. The organic liquid extractant is immobilized in the pores of a microporous polymer material. Under suitable conditions, the analyte of interest partitions into the immobilized organic phase while other matrix speces and interferences are washed away in the mobile aqueous phase. After the wash step, retained analytes are rapidly released in one or more steps by changing the aqueous eluent, such that the analytes now partition back into the mobile phase. The development of solvent impregnated resins, their physical chemistry, technological applications for metal and radionuclide recovery, and analytical uses were described in detail in a previous chapter in this series by Cortina and Warshawsky. The extraction chromatographic approach is well suited for the isolation of radionuclides from complex sample matrixes in a rapid automated format. The development of automated radioanalytical methods is, in fact, closely coupled to the availability of such materials. In this review, we will focus on the application of radiochemical separations in automated fluidic formats for the analysis of alpha- and beta-emitting radionuclides.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 985017
- Report Number(s):
- PNNL-SA-58317; 30400; NN2001000; TRN: US1006056
- Resource Relation:
- Related Information: Ion Exchange and Solvent Extraction: A Series of Advances, Volume 19
- Country of Publication:
- United States
- Language:
- English
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