Determination of Precise 135Cs/137Cs Ratio in Environmental Samples Using Sector Field Inductively Coupled Plasma Mass Spectrometry
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- 作者：Ben C. Russell ; Ian W. Croudace ; Phil E. Warwick ; J. Andy Milton
- 刊名：Analytical Chemistry
- 出版年：2014
- 出版时间：September 2, 2014
- 年：2014
- 卷：86
- 期：17
- 页码：8719-8726
- 全文大小：369K
- ISSN：1520-6882
文摘
Recent advances in sector field inductively coupled plasma mass spectrometry (ICP-SFMS) have led to significant sensitivity enhancements that expand the range of radionuclides measurable by ICP-MS. The increasing capability and performance of modern ICP-MS now allows analysis of medium-lived radionuclides previously undertaken using radiometric methods. A new generation ICP-SFMS was configured to achieve sensitivities up to 80鈥?00 counts per second for a 1 ng/L 133Cs solution, providing a detection limit of 1 pg/L. To extend this approach to environmental samples it has been necessary to develop an effective chemical separation scheme using ultrapure reagents. A procedure incorporating digestion, chemical separation and quantification by ICP-SFMS is presented for detection of the significant fission product radionuclides of cesium (135Cs and 137Cs) at concentrations found in environmental and low level nuclear waste samples. This in turn enables measurement of the 135Cs/137Cs ratio, which varies with the source of nuclear contamination, and can therefore provide a powerful dating and forensic tool compared to radiometric detection of 137Cs alone. A detection limit in sediment samples of 0.05 ng/kg has been achieved for 135Cs and 137Cs, corresponding to 2.0 脳 10鈥? and 160 mBq/kg, respectively. The critical issue is ensuring removal of barium to eliminate isobaric interferences arising from 135Ba and 137Ba. The ability to reliably measure 135Cs/137Cs using a high specification laboratory ICP-SFMS now enables characterization of waste materials destined for nuclear waste repositories as well as extending options in environmental geochemical and nuclear forensics studies.