A rapid separation method for the determination of Tc-99 in environmental waters by ICP-MS

Technetium-99 is an artificial radionuclide with a long half-life of 2.1 x 105 y. The main sources of environmental 99Tc are nuclear weapons tests and nuclear industries such as nuclear fuel processing plants and waste disposal facilities. Due to its high mobility in the terrestrial environment, it is one of the most important radionuclides for does assessment. In this study, the authors propose a separation procedure for Tc in environmental waters using a resin, after which samples can be measured by ICP-MS. Tracer experiments were carried out to determine a suitable concentration of HNO3 for separation of Tc from Ru in environmental waters on TECA·Spectrademark resin. This was necessary, because, with a common procedure, a small amount of Ru was found in the eluate of 12 M HNO3 solution. Ruthenium has an isotopic abundance of 12.7% at mass 99 which interferes with Tc counting by ICP-MS. Most of the Ru sorbed on the resin was desorbed by 40 mL of 2 M HNO3. Sorbed Tc was readily recovered using 4 mL of 8 M HNO3. No Ru was found in the eluate of 9 M HNO3 solution. The authors also checked the concentrations of major elements, such as Mg, Na and Ca, in the eluates passing through the resin column by ICP=AES. It was clear that most of the major elements in the environmental waters, adjusted to 0.1 M HNO3, passed through the resin column and, subsequently, concentration of each coexisting element in the strip solution by 8 M HNO3 was lower than 20 ppm. The procedure was applied to 2 L each for both river water and seawater. The recoveries of Tc for both waters in 4 mL of the strip solution by 8 M HNO3 were more than 98% and the detection limit of 99Tc by this procedure with ICP-MS measurement was 0.3 mB1 L-1