Title: Investigations in Technetium Quantitation
Nell Carver and Robert Jump
Technetium-99 (99Tc) is a long-lived (T_=2.13x105 y) beta-emitting radionuclide (Emax=0.29 MeV). 99Tc can enter the environment from various sources, including nuclear power production, nuclear weapons testing, nuclear waste storage and radiopharmaceutical use. In aqueous solutions that do not contain reducing agents, Tc exists predominantly in anionic form as pertechnetate (TcO4-). Due to its long half-life and high mobility Tc in this form can be a significant environmental concern. Pertechnetate can be separated from most other sample constituents with TEVA® resin in preparation for sample analysis. Results of several investigations into 99Tc sample preparation and analysis are presented. Observations show 99Tc was not volatile in 12 N HNO3 when heated to dryness at temperatures up to 200 °C. Furthermore, volatilization of 99Tc in soil was not observed when heated at temperatures up to 600 °C in a muffle furnace. However, dry ashing should only be employed on problematic soils high in organic matter. Our studies confirm the similar behavior of Re and Tc with TEVA® resin as previously reported. Therefore, Re would appear to be a suitable tracer for 99Tc in water samples and other aqueous solutions. When leaching soil in dilute nitric acid, however, significantly more 99Tc was lost from solution than Re in several cases. Although 99Tc and Re have many chemical similarities the two elements do not always react with soil in an identical manner. Therefore, chemical yields via Re tracer may not be accurate when analyzing 99Tc in soil due to fractionation between Re and 99Tc.
This abstract is submitted for poster format. Abstract topic to fall under:Applications of Radiochemistry to Chemical Problems.