Determination Of Iodine 129 By Icp-Qms In Environmental Samples

The potential of inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) was studied as an alternative to X-ray spectrometry for the measurement of Iodine 129 in environmental samples. Although ICP-MS exhibits attractive features for the measurement of this radionuclide, the occurrence of natural iodine ((127)I) at substantial levels in the solutions recovered after dissolution and extraction steps was shown to induce an interference on the 1291 signal, likely due to the formation of a polyatomic IH(2) species, as well as a substantial matrix effect for quantitative analyses. These difficulties could be overcome by analyzing diluted solutions and using (133)Cs as an internal standard. The use of ICP-MS after sample pre-treatment allowed us to reach detection limits for 1291 in the range of 10(-4) Bq/g (10(-11) g/g). The accuracy of the measurements was estimated in comparison with results obtained on the same samples by X-ray spectrometry.