Direct separation of plutonium by thermochromatography from environmental samples

A thermochromatographic separation was performed on plutonium from environmental soil samples. This procedure was investigated with the goal to measure low concentrations of plutonium by inductively coupled plasma-mass spectrometry (ICP-MS). The soil sample was chlorinated by thionylchloride as reactive gas at a temperature of 1400 K. The volatile chlorides were separated chromatographically and deposited in a temperature gradient tube filled with quartz grains. Results about the deposition behaviour of the elements were obtained. Two different formalisms based on the thermodynamic functions are used to describe the experimental data. One formula is used to describe the deposition behaviour of microscopic amounts of plutonium (adsorption), the other formula for macroamounts of the main matrix elements (desublimation). The calculated values are in a reasonable agreement with the experimental data. A determination of plutonium content was successfully made for a referenced sea sediment (IAEA-135) after the thermochromatographic sample preparation for ICP-MS.