Determination of99Tc in rain and dry fallout by ICP-MS

Abstract

Due to the difficulty of99Tc analysis, data are insufficient for discussing its behavior in the environment. In this study, we focused on the determination of99Tc in rain and dry fallout samples. The samples were collected monthly at Nakaminato, Japan, from June 1993. They were concentrated by heating on a hot plate without any loss of Tc. The solution was filtrated and then a liquid-liquid extraction (LLX) with trioctylamine (TOA), which works as a liquid anion exchanger, was carried out. Technetium was extracted from 5% HNO3 solution into the organic phase with a high extractability. After being back-extracted from TOA/xylene into 1M K2CO3, LLX with cyclohexanone was used to remove ruthenium, which has a stable isotope of mass 99. Technetium was back-extracted into deionized water, and the solution was measured by inductively coupled plasma mass spectrometry (ICP-MS). The average recovery under the experimental conditions was 67% and the instrumental detection limit was 0.04 ppt (0.03 mBq/mL).