Use of combustion apparatus for low-level {sup 99}Tc separations from soil samples

Analysis data of global fallout {sup 99}Tc in environmental samples should give useful information for predicting the nuclide's behavior. However, due to its low concentration and analytical difficulties with environmental samples, there are not many data. The authors improved a simple separation method, which had been previously reported for Tc in soil samples and used a combustion apparatus. In this study, two fundamental experiments were performed; one clarified the possibility of using deionized water for a trap solution instead of an alkaline solution, and the other checked for differences in Tc volatilities between 1-y-aged {sup 99}Tc and freshly added {sup 95m}Tc in a soil sample. The results showed that deionized water can trap volatilized Tc as well as alkaline solution, and the volatilities of aged {sup 99}Tc and freshly added {sup 95m}Tc from the soil sample do not differ. The procedure proposed is as follows: Tc in a soil sample is volatilized in a combustion apparatus for 3 h at 1000{degree}C and trapped in deionized water. Then the trap solution is passed through an extraction chromatographic resin (TEVA {center{underscore}dot} Spec{trademark} resin). After the eluate (ca. 8 M HNO{sub 3}) is evaporated to dryness and dissolved in a 2% HNO{sub 3}more » solution, the {sup 99}Tc concentration in the solution is measured by inductively coupled plasma mass spectrometry (ICP-MS). This method was employed to measure three environmental soil samples collected in Japan. The recoveries and {sup 99}Tc concentrations were 62--73% and 5--30 mB1/kg dry basis, respectively.« less