Automated radiochemical separation

Extraction chromatographic methods generally provide columns with high capacities, tolerate high levels of potential interferences and a variety of sample matrixes, allow flexibility in sample loading conditions, and work at low pressures. These are the features that are well suited for radiochemical separations in general and automated radiochemical separations in particular. 

Grate, J. W. and Egorov, O. B., Automated radiochemical separation, analysis, and sensing, in Handbook of Radioactivity Analysis, 2nd ed., L Annunziata, M. F., Ed., Elsevier, Academic Press San Diego, 2003,1129-1164. 

Laboratory robotics represents an attractive approach for the automation of sample preparation and separation steps in radiochemical analysis, and for many years, such methods have been routinely used by laboratories serving the analytical needs of the International Atomic Energy Association.64 68-72 However, there are currently a limited number of published studies containing technical details on the radiochemical separations and how they were automated. Accordingly, the remainder of this chapter will focus on fluidic approaches. 

By the late 1990s and into the 2000s, a number of additional groups became involved in automated fluidic separations for radiochemical analysis, especially as a front end for ICP-MS. Published journal articles on fluidic separations for radio-metric or mass spectrometric detection are summarized in Tables 9.1 through 9.5. The majority of such studies have used extraction chromatographic separations, and these will be the main focus of the remainder of this chapter. Section 9.4 describes methods that combine separation and detection. Section 9.5 describes a fully automated system that combines sample preparation, separation, and detection. 

Conventional radiochemical analysis of nuclear process or waste samples in the laboratory entails three primary activities sample preparation, radiochemical separation, and detection. Each of these activities may entail multiple steps. The automated fluidic methods described above, typically also carried out in the laboratory, link separation and detection. Sample preparation has, in many cases, been carried out first by manual laboratory methods. 

Scientists at PNNL have developed an automated radiochemical sample preparation-separation-detection system for the determination of total "Tc in nuclear-waste process streams.46 85 86 144145 This analyzer was designed to support a technetium removal process planned as part of the development of a nuclear-waste processing plant. The process stream composition is both complex and variable, with a high pH, high salt matrix. Depending on the source of the feed, the total base content, the concentration of organics, and complexant concentrations will vary, as will the aluminum, nitrate, nitrite, dichromate, and radionuclide composition. 

The development of solvent-impregnated resins and extraction-chromatographic procedures has enabled the automation of radiochemical separations for analytical radionuclide determinations. These separations provide preconcentration from simple matrices like groundwater and separation from complex matrixes such as dissolved sediments, dissolved spent fuel, or nuclear-waste materials. Most of the published work has been carried out using fluidic systems to couple column-based separations to on-line detection, but robotic methods also appear to be very promising. Many approaches to fluidic automation have been used, from individual FI and SI systems to commercial FI sample-introduction systems for atomic spectroscopies. 

Instead, an automated radiochemical process monitor is required that takes a sanple aliquot from the process, adjusts die sample matrix and the analyte speciation, separates the analyte from interfering species, and finally quantifies... 

Although Meinke (603) points out that automation in analytical chemistry is most desirable to remove the drawbacks of radiochemical separations in activation analysis, many other analysts who use activation analysis for trace element determinations in biological materials continue effective research on separation systems for a single element or a small group of elements with similar chemical characteristics for example, the methods and techniques in the publication by Gorsuch (338) have been used by many analysts in their activation analysis determinations of trace elements. Other successful microchemical techniques used in activation analysis have been described by Pijck and Hoste (713), Sion, Hoste, and Gillis (858), Girardi and Merlini (331), and Smales and Mapper (864). 

Separation by extraction chromatographic materials appears as the most suitable technique to develop automated radiochemical methodologies followed by LLE. There are a large number of selective resins for radionuclides determination, e.g. Ra, Ni, Pb, Th, U, Np, Pu, Am, Cm, Sr, Tc, H, Fe and Pa [4], which have been largely included in protocols with online separation [5—8]. Automatic separation exploiting flow systems can also be carried out by LLE which involves the formation of complexes between several organic compounds and radionuclides [9—11]. 

Meyer, R.A. Rapid automated batchwize radiochemical separation techniques. J. Radioanal. Nucl. Chem. Art. 142, 135-144 (1990)... 

Many laboratories employ radiochemical separation techniques to isolate groups of elements from the sample after irradiation. The combination of simple group separations and high-resolution gamma-ray spectroscopy reduces substantially the analysis time and analytical costs, and makes the technique nearly a true multielement method. Additional effort is being expended to automate these group separations to further decrease analytical costs. 

Q Automation of Extraction Chromatographic and Ion Exchange Separations for Radiochemical Analysis and Monitoring... 

TLRC can be used for animal, human, and plant metabolism analysis radiochemical purity and stability assessment toxicology and biochemical studies and separation, detection, and quantification of separated radioactive zones of all compound classes. Traditional film autoradiography and LSC continue to be widely used, but phosphor imaging and layer scanners are being increasingly applied. The instruments for these methods are highly automated and... 

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