Rapid Radiochemical Method for Total Radiostrontium (Sr-90) In Building Materials for Environmental Remediation Following Radiological Incidents

September 2014 Update: EPA has validated and published a rapid method for building material
matrices for analysis of strontium-89 and strontium-90. The method is summarized and accessible
through the link provided below.
Rapid Radiochemical Method for Total Radiostrontium (Sr-90) In Building Materials for
Environmental Remediation Following Radiological Incidents
Analyte(s)
CAS RN
Strontium-89
14158-27-1
Strontium-90
10098-97-2
Analysis Purpose: Qualitative analysis
Technique: Beta counting
Method Developed for: Strontium-89 and strontium-90 in building materials
Method Selected for: SAM lists this method for qualitative analysis of strontium-89 and strontium-90 in
concrete or brick building materials
Description of Method: Strontium is collected and purified from concrete or brick matrix samples using
sodium hydroxide fusion, and purified from potentially interfering radionuclides and matrix constituents
using a strontium-specific, rapid chemical separation method. The sample is equilibrated with strontium
carrier, and preconcentrated by strontium/calcium carbonate coprecipitation from the alkaline fusion
matrix. The carbonate precipitate is dissolved in hydrochloric acid and strontium is precipitated with
calcium fluoride to remove silicates. The strontium fluoride precipitate is dissolved in strong nitric acid
and the solution is passed through a Sr Resin extraction chromatography column. The sample test source
is promptly counted on a gas flow proportional counter to determine the beta emission rate, which is used
to calculate the total radiostrontium activity. The method is capable of satisfying a method uncertainty for
strontium-90 (total strontium-90) of 0.31 pCi/g at an analytical action level of 2.4 pCi/g. To attain the
stated measurement quality objectives (MQOs), a sample weight of 1.5 g and a count time of
approximately 1.5 hours are recommended.
If differentiating between strontium-89 and strontium-90 is needed, then the same prepared sample can be
recounted after -10 days. If the initial and second counts agree (based on the expected ingrowth of
yttrium-90) then strontium-89 is not present in significant amounts relative to strontium-90.
Computational methods are available for resolving the concentration of strontium-89 and strontium-90
from two sequential counts of the sample (see Appendix B of the method). If significant amounts of
strontium-89 are suspected, it can be determined more rapidly using Cerenkov counting; however, the
minimum detectable activity levels will be higher than that of determination with gas proportional
counting and may or may not meet measurement quality objectives.
Special Considerations: Count results should be monitored for detectable alpha activity and appropriate
corrective actions should be taken when observed. Failure to address the presence of alpha emitters in the
sample test source may lead to high bias in the results, due to alpha-to-beta crosstalk.
Elevated levels of radioisotopes of tetravalent plutonium, neptunium, cerium, and ruthenium in the
sample may hold up on the column and co-elute with strontium. The method employs an oxalic acid rinse
that should address low to moderate levels of these interferences. Significant levels of strontium-90 will
interfere with the total radiostrontium analysis (see Appendix B of the method for an alternative approach
should this situation arise). High levels of lead-210 may interfere with low level strontium analysis due
to ingrowth of short-lived bismuth-210 during chemical separations, where lead is retained by the Sr
Resin, but is not eluted. If lead-210 is known to be present in samples, minimizing the time between the
U.S. Environmental Protection Agency
Office of Research and Development, Homeland Security Research Program
EPA/600/F-14/282
September 2014

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final rinse and the elution of strontium to less than 15 minutes will minimize the levels of interfering
bismuth-210.
Source: U.S. EPA, National Air and Radiation Environmental Laboratory (NAREL). April 2014. Rev
0 "Rapid Radiochemical Method for Total Radiostrontium (Sr-90) In Building Materials for
Environmental Remediation Following Radiological Incidents," EPA 402-R14-001.
http://www.epa.gov/sam/pdfs/EPA-4Q2-R14-001 .pdf
U.S. Environmental Protection Agency
Office of Research and Development, Homeland Security Research Program
EPA/600/F-14/282
September 2014

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