Radiochemistry analysis of 99Tc in environmental samples

Full text: Measurement of 99Tc with ICP-MS is feasible due to low determination limit. When compared to classical method beta counting the modern ICP-MS instruments reach even three orders of magnitude lower determination limits. However, for efficient analysis the sample needs to be free of interfering agents such as isotopes of other elements and polyatomics. The main interferences in the mass spectra of 99Tc are 99Ru and, to some extent, 98MoH, 59Co40Ar, 87Sr12C, 87Rb12C, 43Ca16O40Ar, 40Ar218OH and 40Ca18OH40 can be removed in the chemical separation procedure, for example, by using TEVA resin, but when working with large samples and using large amounts of reagents, absolute clean up can be difficult. The amount of Ru in the sample can be calculated from its relatively undisturbed isotope 101Ru, however, this decreases the determination limit of 99Tc which is problematic with samples of low 99Tc concentration. Large amounts of Mo in samples create a problem for measurement of Tc via the interference of 98Mo-hydride. Another issue with Mo is the interference of 97Mo isotope when 97Tc is used as yield tracer. In this work HPLC pump and ion chromatography column has been applied in the separation chain for aiming to separate Tc from Mo and Ru and thus yield a pure Tc fraction for measurement with ICP-MS. Different complexing agents have been applied to study the separation efficiency of Tc in the column both in reduced and oxidized form. This talk will give an overview of radioanalytical methods used in our laboratory for Tc as well as the results obtained with the applied chromatographic experiments. (author)