Determination of extremely low 236U/238U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry using high-efficiency sample introduction
Determination of extremely low 236U/238U isotope ratios in environmental samples by sector-field inductively coupled plasma mass spectrometry using high-efficiency sample introduction
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DOI：
10.1016/j.jenvrad.2005.12.007
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发表时间：
2006-01-01
影响因子：
2.3
通讯作者：
Heumann, KG
中科院分区：
文献类型：
--
作者：
Boulyga, SF;Heumann, KG
开发了一种电感耦合等离子体质谱法（ICP-MS），该方法可以测量土壤样品中浓度范围低至3 x 10（-14）g g（-1）的U-236和极低的U-236/U-238同位素比（10（-7））。通过使用高效溶液引入系统APEX与扇形场ICP-MS连接，实现了超过5000个fg（-1）铀计数的灵敏度。气溶胶去溶剂化装置的使用将铀氢化物离子UH+/ U+的形成速率降低到10（-6）的水平。在质量分辨率为4000时，观察到铀-236/铀-238同位素比测量的丰度灵敏度为3 × 10 - 7。与α能谱法相比，U-236的检出限和最低检出U-236/U-238同位素比值提高了两个数量级以上。对切尔诺贝利核电站附近土壤样品中铀的测定表明，与U-235/U-238同位素比相比，U-236/U-238同位素比是一种更为敏感和准确的乏铀环境污染标志。电感耦合等离子体质谱技术首次允许检测土壤样品中的辐照铀，即使在距离切尔诺贝利核电站以北200多公里的地方（莫吉廖夫地区）。铀-236在0-10厘米土层上层的浓度从切尔诺贝利核电站附近放射性点的2x 10（-9）克/克到距离切尔诺贝利200公里以上取样点的3x 10（-13）克/克不等。(c)2005爱思唯尔有限公司保留所有权利。
A method by inductively coupled plasma mass spectrometry (ICP-MS) was developed which allows the measurement of U-236 at concentration ranges down to 3 x 10(-14) g g(-1) and extremely low U-236/U-238 isotope ratios in soil samples of 10(-7). By using the high-efficiency solution introduction system APEX in connection with a sector-field ICP-MS a sensitivity of more than 5000 counts fg(-1) uranium was achieved. The use of an aerosol desolvating unit reduced the formation rate of uranium hydride ions UH+/ U+ down to a level of 10(-6). An abundance sensitivity of 3 x 10(-7) was observed for U-236/U-238 isotope ratio measurements at mass resolution 4000. The detection limit for U-236 and the lowest detectable U-236/U-238 isotope ratio were improved by more than two orders of magnitude compared with corresponding values by alpha spectrometry. Determination of uranium in soil samples collected in the vicinity of Chernobyl nuclear power plant (NPP) resulted in that the U-236/U-238 isotope ratio is a much more sensitive and accurate marker for environmental contamination by spent uranium in comparison to the U-235/U-238 isotope ratio. The ICP-MS technique allowed for the first time detection of irradiated uranium in soil samples even at distances more than 200 km to the north of Chernobyl NPP (Mogilev region). The concentration of U-236 in the upper 0-10 cm soil layers varied from 2 x 10(-9) g g(-1) within radioactive spots close to the Chernobyl NPP to 3 x 10(-13) g g(-1) on a sampling site located by > 200 km from Chernobyl. (c) 2005 Elsevier Ltd. All rights reserved.