Rapid Method for Sodium Hydroxide Fusion of Asphalt Matrices Prior to Americium, Plutonium, Strontium, Radium, and Uranium Analyses Analyte(s) CAS RN® Americium-241 14596-10-2 Plutonium-238 13981-16-3 Plutonium-239 15117-48-3 Radium-226 13982-63-3 Strontium-90 10098-97-2 Uranium-234 13966-29-5 Uranium-235 15117-96-1 Uranium-238 7440-61-1 Analysis Purpose: Qualitative analysis Technique: Alpha spectrometry Method Developed for: Americium-241, plutonium-238, plutonium-239, radium-226, strontium-90, uranium-234, uranium-235 and uranium-238 in asphalt samples Method Selected for: SAM will list this method for qualitative analysis of americium-241, plutonium-238, plutonium-239, radium-226, strontium-90, uranium-234, uranium-235 and uranium-238 in asphalt matrices. Description of Method: The asphalt samples may be received as core samples, crushed samples or in pieces of various sizes. The term "asphalt" is used in the method to mean asphalt typically used for road surfaces. The precise particle size of the milled sample is not critical to subsequent processes, however milling the sample to smaller particle sizes (~ 600 micron particle size) and thorough mixing facilitates representative subsampling. Milling to a smaller particle size also facilitates a homogeneous dispersion of particles. The method is based on heating a representative, finely milled 1 to1.5 grams (g) aliquant asphalt sample to remove organic components present followed by rapid fusion using sodium hydroxide fusion at 600 °C. Plutonium (Pu), uranium (U), and americium (Am) are separated from the alkaline matrix using an iron/titanium hydroxide precipitation (enhanced with calcium phosphate precipitation) followed by a lanthanum fluoride matrix removal step. Strontium (Sr) is separated from the alkaline matrix using a phosphate precipitation, followed by a calcium fluoride precipitation to remove silicates. Radium (Ra) is separated from the alkaline matrix using a carbonate precipitation. The method is applicable to the sodium hydroxide fusion of asphalt samples, prior to the chemical separation procedures described in the following procedures: • U.S. EPA. Rapid Radiochemical Method for Americium-241 in Building Materials for Environmental Remediation Following Radiological Incidents (EPA 402-R14-007, April 2014) • U.S. EPA. Rapid Radiochemical Method for Plutonium-238 and Plutonium-239/240 in Building Materials for Environmental Remediation Following Radiological Incidents (EPA 402-R14-006, April 2014) • U.S. EPA. Rapid Radiochemical Method for Radium-226 in Building Materials for Environmental Remediation Following Radiological Incidents (EPA 402-R14-002, April 2014) • U.S. EPA. Rapid Radiochemical Method for Total Radiostrontium (Sr-90) in Building Materials for Environmental Remediation Following Radiological Incidents (EPA 402-R14-001, April 2014) • U.S. EPA. Rapid Radiochemical Method for Isotopic Uranium in Building Materials for Environmental Remediation Following Radiological Incidents (EPA 402-R14-005, April 2014) U.S. Environmental Protection Agency Office of Research and Development, Homeland Security Research Program EPA/600/S-16/281 September 2016 ------- Special Considerations: Asphalt samples with larger particle size may require a longer fusion time. Information regarding the elemental composition of the sample may be helpful to determine any native concentrations of uranium (U), radium (Ra), thorium (Th), strontium (Sr), or barium (Ba), all of which can have an effect on the chemical separations used following the fusion of the sample. In those samples where native constituents are present that could interfere with the determination of the chemical yield (e.g., strontium for 90Sr analysis) or with the creation of a sample test source (e.g., Ba for 226Ra analysis by alpha spectrometry), it may be necessary to determine the concentration of these native constituents in advance of chemical separation (using a separate aliquant of fused material) and make appropriate adjustments to the yield calculations or amount of carrier added. Matrix blanks for these matrices might not be practical to obtain. Efforts should be made to obtain independent, analyte-free materials that have similar composition as the samples to be analyzed. These blanks will serve as process monitors for the fusion, and as potential monitors for cross contamination during batch processing. Re-used zirconium crucibles should be cleaned very well using soap and water, followed by warm nitric acid, and a final water rinse. Blank measurements should be monitored to ensure effective cleaning. Additional information regarding potential interferences and procedures for addressing the interferences is provided in Section 4 of the method. Source: U.S. EPA, National Air and Radiation Environmental Laboratory (NAREL). "Rapid Method for Sodium Hydroxide Fusion of Asphalt Matrices Prior to Americium, Plutonium, Strontium, Radium, and Uranium Analyses." EPA 402-R16-001, Revision 0, August 2016. https://www.epa.gov/radiation/rapid- radiochemical-methods-selected-radionuclides U.S. Environmental Protection Agency Office of Research and Development, Homeland Security Research Program EPA/600/S-16/281 September 2016 ------- |