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

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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

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