Measurement of I-129 in environmental samples by ICP-CRI-QMS: possibilities and limitations

摘要

I-129 is preconcentrated from environmental samples and its accessibility is addressed for inductively coupled plasma quadrupole mass spectrometer with collision/reaction interface (ICP-CRI-QMS). By applying oxygen as CRI gas through skimmer cone, the signal of the interfering Xe-129 from the impurity of plasma gas can be eliminated while the formation of (IHH+)-I-127-H-1-H-1 can be partially removed. The improved ICP-QMS can be employed for investigation of I-129 in environmental samples with a I-129/I-127 ratio down to 10(-7). The detection capability was demonstrated by measuring I-129 in seaweed samples collected around the nuclear fuel reprocessing plant at La Hague. The abundant I-129 in the sample matrix causes a serious problem and degrades the detection capability of the instrument when the concentration of I-129 is larger than 10(5) g/g. Even combined with a sufficient pre-concentration procedure, ICP-QMS is not considered as a Suitable technique for the analysis of I-129 in uncontaminated environmental samples with I-129/I-127 ratio of less than 10(-7). Results are presented for seaweed samples collected around La Hague. In addition, time dependant I concentrations and ratios are given for colloids and water sampled from Lake Thun.