Separation Procedure for the Determination of Technetium-99 in Soil by ICP-MS

Abstract

A simple method for determination of "Tc in soil by ICP-MS is reported. The procedures involved are as follows: 1) Technetium is volatilized in a combustion apparatus for 3 hours at 950°C and trapped in a K2CO3 Solution. 2) After addition of H2O2, technetium is extracted into cyclohexanone to remove Ru which has also an isotope of mass 99. 3) Tc in the organic layer is back-extracted into deionized water. 4) The Solution is acidified with HNO3, and ^'Tc is measured by inductively coupled plasma mass spectrometry (ICP-MS). The chemical recovery in the whole procedure is 52-64%. The temperature at which '®Tc in soil begins to evaporate was also investigated with the combustion apparatus. The technetium-99 concentration and the ®'Tc/'^''Cs ratio were determined in soil samples collected in Japan.

Determination of technetium-99 in environmental samples: A review

“…This is a very critical step in the analysis of solid samples for 99 Tc, because incomplete decomposition of organic matters and volatile loss of 99 Tc in this stage will cause an insufficient leaching of 99 Tc from the samples and poor yield of 99 Tc. Some reports suggest that 99 Tc losses occur at a temperature around 550 0 C [8,83], whereas others reported an insignificant loss of 99 Tc even at as much as 800 0 C [84,85]. It has been reported that the loss of 99 Tc can be reduced if the samples are wetted with concentrated HCl before ashing [5].…”

“…Oxidizing combustion methods can also be used for releasing 99 Tc from solid samples [85,94]. This method is based on the volatility of Tc in oxidative medium and at high temperature.…”

“…The 99 Tc in sample is converted to volatile Tc 2 O 7 and released from the sample, which is transported by the gas flow and trapped in alkaline solution or just water [85,94]. Compared with alkali fusion, the combustion method can be used to treat large samples using a big tube oven, and most of the matrix components as well as many interfering radionculides and stable elements can be directly removed from the 99 Tc because of their lesser volatility in the combustion conditions.…”

“…Tc was first synthesized and isolated by Perrier et al in 1937 as a product from the bombardment of molybdenum with deuterons or neutrons [1]. So far 45 isotopes of Tc, ranging from 85 Tc to 117 Tc, have been synthesized, and most of them are short-lived isotopes with half lives of less than one hour. Table 1 lists the isotopes of Tc with half lives exceeding one hour.…”

The use of 99mTc as a tracer in the determination of 99Tc by ICP-mass spectrometry

“…2±4 Nevertheless, some environmental issues still remain unexplored for 99 Tc and only the recent use of mass spectrometry has enabled the scienti®c community to meet the experimental challenge of 99 Tc determination at very low levels. ICP-MS, 5 RIMS 6 and even accelerator mass spectrometry (AMS) 7 have been used to determine 99 Tc in a variety of environmental samples. Comparisons between radiometric and non-radiometric methods have also been carried out.…”