Rapid Method for ICP-MS Analysis of Plutonium in Sediment Samples
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5DSLG0HWKRGIRU,&306$QDO\VLVRI3OXWRQLXPLQ6HGLPHQW6DPSOHV Christina Greis1, Anders Düker1, Håkan Pettersson2, Stefan Karlsson1 and Bert Allard1 Man-Technology-Environment Research Centre, Örebro Univ., SE-701 82 Örebro, SWEDEN 2 Department of Radiation Physics, Linköping Univ., SE-581 85 Linköping, SWEDEN
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$%675$&7 A rapid and reliable method for quantification of transuranium elements in environmental samples is required from the aspect of emergency preparedness. Determination of these elements in e.g. sediment samples includes three steps: sample dissolution, chemical separation and measurement. Different acids were used for leaching of plutonium, americium and neptunium from contaminated sediment (during heating or microwave digestion). Chemical separation was performed by co-precipitation (with Fe(OH)3 or NdF3), by anion exchange or by liquid-liquid extraction (with tributylphosphate, trioctylamine and thenoyl trifluoroacetone, respectively). The following radioisotopes were quantified by quadrupole ICP-MS equipped with an ultrasonic nebulizer (USN): 237Np, 239Pu, 240Pu, 241Pu, 242Pu and 241Am. Data are only given for 239Pu and 240 Pu in this paper. Plutonium was also measured by alpha spectrometry in some samples, as well as 137Cs and 241Am by gamma spectrometry. The agreement between concentrations of plutonium obtained by ICP-MS and alpha spectrometry was good, which demonstrates that a simple and rapid procedure for analysis of plutonium by quadrupole ICP-MS is feasible. ,1752'8&7,21 Plutonium is present in ultra-trace amounts in nature as 239Pu in uranium ores, originating from the capture of cosmic neutrons by 238U [1]. The main source of plutonium in the environment is, however, from nuclear weapons testing. Atmospheric tests during the 1950s and 1960s resulted in significant depositions almost world-wide. Local discharges related to nuclear power production represent possible future sources. The importance of establishing techniques for reliable determination of transuranium elements, including plutonium, in various environmental samples is obvious. Improved techniques for rapid determination is of particular concern from the aspect of emergency preparedness. Procedures for such analyses must be rapid and easy to perform at many laboratories without a too high level of sophistication. Tracing the source from measurements of the isotopic composition of a particular element is another important aspect to take into consideration. Alpha spectrometry has been widely used but has disadvantages. The low concentrations of transuranium elements in environmental samples combined with long half-lives result in long counting times. Due to similar alpha energies the technique can not distinguish between e.g. 239Pu and 240Pu. High resolution ICP-MS offers fast analyses with high mass resolution at acceptable detection limits. For emergency preparedness under Swedish conditions, however, the limited abundance of high-resolution ICP-MS instruments limits the practical use. Quadrupole ICP-MS is more
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