Application of a High Throughput Microwave Digestion System for the Determination of Radionuclides in a Variety of Matrices

D. K. Mann and A.M. Likens, Lockheed Martin Energy Systems Inc, Analytical Chemistry Organization, 113C Union Valley Road, Oak Ridge, TN 37830, USA

The use of microwave digestion as a tool for the solubilization of a variety of matrices has become commonplace in the modern analytical laboratory. One drawback to the use of microwave technology has been the limited number of samples which can be done per batch. To overcome this limitation, a MARS 5 (CEM, Matthews, NC) microwave system was retrofitted with a High Throughput Carousel (HTC). The retrofitted MARS 5 system allowed the temperature controlled digestion of up to 52 samples in a single batch using disposable, self standing 50 ml centrifuge tubes (Corning Inc., Corning, NY). Use of the disposable centrifuge tubes allowed the same container to be used from sample collection, through digestion, to final dilution and analysis. The system was used to digest Health Physics smears for the determination of isotopic uranium, plutonium, neptunium and americium. Recoveries were the same or better than those reported for the traditional hot plate method, ranging from 60 to 95 percent. Digestion time was reduced from over 12 hours to under 1 hour. Cross contamination was virtually eliminated. The application of this system to other matrices, such as soils, solids, neodymium fluorides disks, and disposable quartz crucibles is discussed.

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