EPA-600-R-12-640
www.epa.gov/narel
August 2012
Revision 0
Rapid Method for Sodium Carbonate Fusion of
Soil and Soil-Related Matrices Prior to
Strontium-90 Analyses for Environmental
Remediation Following Radiological Incidents
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Radiation and Indoor Air
National Air and Radiation Environmental Laboratory
Montgomery, AL 36115
Office of Research and Development
National Homeland Security Research Center
Cincinnati, OH 45268
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Rapid Method for Sodium Carbonate Fusion of Soil and Soil Related Matrices Prior to Strontium-90 Analysis
Revision History
Revision 0 I Revision 0 I 08-31-2012
This report was prepared for the National Air and Radiation Environmental Laboratory of the Office of
Radiation and Indoor Air and the National Homeland Security Research Center of the Office of Research
and Development, United States Environmental Protection Agency. It was prepared by Environmental
Management Support, Inc., of Silver Spring, Maryland, under contract EP-W-07-037, work assignments I-
41 and 2-43, both managed by Dan Askren. Mention of trade names or specific applications does not
imply endorsement or acceptance by EPA.
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RAPID METHOD FOR SODIUM CARBONATE FUSION OF SOIL AND SOIL RELATED MATRICES
PRIOR TO STRONTIUM-90 ANALYSIS
1. Scope and Application
1.1. The method is applicable to the fusion digestion of soil and soil related matrices (e.g.,
sediments, dry deposition samples, loam, etc.).
1.2. This is a general method for soil samples, dry particulate deposition samples, and
sediments collected following a radiological or nuclear incident.
1.3. Alternative rapid methods exist for sodium carbonate fusion of americium, plutonium,
or isotopic uranium (see Reference 16.2), and radium-226 (see Reference 16.3) in soil
matrices. These fusion methods lead into analyses using the published rapid methods
for radionuclides in water (see Reference 16.5).
1.4. The dissolution by fusion of soils, or related matrices, by this method is expected to
take approximately 2-3 hours per batch of 20 samples. This assumes the laboratory
starts with a representative, finely ground, 1-g aliquant of dried sample.l An initial
sample combustion at 600 °C is necessary for removal of any organic matter prior to
fusion, unless it has been established that the amount of organic matter present will not
interfere with the analytical separations.
1.5. Soil samples must be dried and ground to at least 50-100 mesh size prior to fusion. A
Rapid Technique for Milling and Homogenizing Soil Samples is included as Appendix
A to this method.
1.6. This method combines the sample preparation by fusion, strontium separation, and
sample test source preparation in one method. The method differs from the previously
published method for strontium in water, "Rapid Radiochemical Method for Total
Radiostrontium (Sr-90) in Water for Environmental Restoration Following Homeland
Security Events (see Reference 16.5)," due to unique separation issues that arose during
method validation. However, Step 11.25 of this method merges into and proceeds with
Step 11.11 of the water method.
1.7. Application of this method by any laboratory should be validated by the laboratory
using the protocols provided in Method Validation Guide for Qualifying Methods Used
by Radioanalytical Laboratories Participating in Incident Response Activities (see
Reference 16.1), or the protocols published by a recognized standards organization for
method validation.
1.7.1. In the absence of project-specific guidance, measurement quality objectives
(MQOs) for soil samples may be based on the Analytical Action Levels (AALs)
and Required Method Uncertainties (MMR and ^MR) found in the Radiological
Sample Analysis Guide for Incident Response — Radionuclides in Soil, (see
Reference 16.4).
1 The laboratory should have a separate method for achieving sub-sampling of the sample based on grinding, mixing
and sizing the sample to achieve aliquant uniformity.
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2. Summary of Method
2.1. The method is based on the complete fusion of a representative, finely ground 1-g
aliquant of dried sample with no insoluble residue remaining after dissolution of the
fused melt in acid.
2.2. For media composed of organic soil matrices, the sample is dry-ashed at 600 °C in an
appropriate vessel prior to fusion.
3. Definitions, Abbreviations and Acronyms
3.1. Discrete Radioactive Particles (DRPs or "hot particles"). Particulate matter in a sample
of any matrix where a high concentration of radioactive material is present as a tiny
particle (um range).
3.2. Multi-Agency Radiological Analytical Laboratory Protocol (MARLAP) Manual (see
Reference 16.5).
3.3. The use of the term soil throughout this method is not intended to be limiting or
prescriptive, and the method described herein refers to all soil related materials such as
sand, humic/fulvic soils, peat, loam, sediment, etc. In cases where the distinction is
important, the specific issues related to a particular sample type will be discussed.
4. Interferences and Limitations
NOTE: Large amounts of extraneous debris (pebbles larger than Vi", non-soil related debris, plant
roots, etc.) are not generally considered to be part of a soil matrix. When consistent with DQOs,
these should be removed from the sample prior to drying. It is recommended, that this be verified
with incident command before discarding any materials.
4.1. Soils with high silica content may require either additional fusing reagent and boric
acid or a longer fusion melt during Step 11.11.
4.2. Soil and soil-related matrices contain a wide variety of elements in the ppm and higher
concentration range. As much information regarding the elemental composition of the
sample should be obtained as possible. For example some soils may have native
concentrations of uranium, thorium, strontium or barium, all of which may have an
effect on the chemical separations used following the fusion of the sample. It is
recommended that elemental analysis of the digest for strontium prior to chemical
separations be performed to determine native concentrations of strontium present in the
sample.
4.3. Matrix blanks for these soil and soil-related matrices may 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 will serve as process monitors for the
fusion, and as potential monitors for cross contamination during batch processing.
4.4. Samples with elevated activity or samples that require multiple analyses from a single
soil sample may need to be split after dissolution. In these cases the initial digestate and
the split fractions should be carefully measured to ensure that the sample aliquant for
analysis is accurately determined.
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4.4.1. Tracer or carrier amounts (added for yield determination) may be increased
where the split allows for the normal added amount to be present in the
subsequent aliquant. For very high activity samples, the addition of the tracer or
carrier may need to be postponed until following the split, in which case special
care must be taken to ensure that the process is quantitative until isotopic
exchange with the yield monitor is achieved. This deviation from the method
should be thoroughly documented and reported in the case narrative.
4.5. The analytical results for this method are reported directly in units of pCi/g.
4.6. In the preparation of blank samples, LCSs and duplicates, care should be taken to create
these QC samples as early in the process as possible, and to follow the same
tracer/carrier additions, digestion process, and sample splitting used for the field
samples. In the case of this method, QC samples should be initiated at the point samples
are aliquanted into crucibles for the fusion.
4.7. Platinum crucibles are required to withstand the harsh conditions of the digestion and
fusion processes used in this method.
4.7.1. The laboratory must develop effective processes for cleaning crucibles. The
effectiveness of the cleaning process should be demonstrated through measures
such as measurements of fusion blanks.
4.7.2. Segregation of crucibles used for low and high activity samples is recommended
to minimize the risk of cross-contamination while maximizing the efficient use
of crucibles. See Rapid Method for Sodium Hydroxide Fusion of Concrete
Matrices prior to Am, Pu, Sr, Ra, and U Analyses (see Reference 16.6) and
RapidRadiochemicalMethodfor Total Radiostrontium (Sr-90) in Building
Materials for Environmental Remediation Following Radiological Incidents
(see Reference 16.7).
5. Safety
5.1. General
5.1.1. Refer to your laboratory safety manual for concerns of contamination control,
personal exposure monitoring and radiation dose monitoring.
5.1.2. Refer to the laboratory chemical hygiene plan (or equivalent) for general safety
rules regarding chemicals in the workplace.
5.2. Radiological
5.2.1. Discrete Radioactive Particles (DRPs or Hot Particles)
5.2.1.1. Hot particles will be small, on the order of 1 mm or less. DRPs are
typically not evenly distributed in the media and their radiation
emissions are not uniform in all directions (anisotropic).
5.2.1.2. Soil media should be individually surveyed using a thickness of the solid
sample that is appropriate for detection of the radionuclide decay
particles.
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5.2.2. The sample size initially dried and homogenized should be of adequate size to
conduct all required measurements but not too large as to cause a potential for
generating airborne contamination.
NOTE: The information regarding DRPs should accompany the samples during processing as well
as be described in the case narrative that accompanies the sample results.
5.3. Procedure-Specific Non-Radiological Hazards:
5.3.1. This procedure employs molten salts generated at high temperatures (~ 1,000
°C) in an open flame. The operator should exercise extreme care when using the
burners and when handling the hot crucibles. Thermal protection gloves and a
face shield are recommended when performing this part of the procedure. The
entire fusion process should be carried out in a laboratory fume hood.
6. Equipment and Supplies
NOTE: For samples with elevated activity concentrations of these radionuclides, labware should be used
only once due to potential for cross contamination unless the cleaning process is demonstrated to be
effective in removing residual contamination. The laboratory quality manual should provide guidance for
making these decisions.
6.1. Adjustable temperature laboratory hotplates.
6.2. Balance, top loading or analytical, readout display of at least ± 0.01 g.
6.3. Beakers, 250 mL capacity.
6.4. Crucibles, minimum capacity, 50 mL, platinum.
6.5. Dispensing pipette, 10 mL delivery volume. Alternately, a bottle-top dispenser, small
volume graduated cylinder, or any other device for delivering nominal 10 mL volumes
of reagent into a beaker or disposable cup.
6.6. Fisher blast burner or Meeker burner.
NOTE: Ordinary Bunsen burners will not achieve the high temperatures needed for fusion.
6.7. Ring stand with ceramic triangle (optional).
6.8. Drying oven.
6.9. Programmable muffle furnace capable of reaching at least 600 °C
6.10. Teflon spatula or glass rod.
6.11. Tongs for handling crucibles, platinum tipped.
6.12. Ten (10) mL transfer pipette.
6.13. Tweezers or forceps.
NOTE: See appendix for a method for ball-milling and homogenization of soils.
6.14. Sample size reduction equipment (ball mill, paint shaker, etc) and screens. The
necessary equipment will be based on a laboratory's specific method for the process of
producing a dry uniformly ground sample from which to procure an aliquant.
6.15. Filters, 0.45 micron, Environmental Express Flipmate filters or equivalent.
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6.16. Plastic backed absorbent paper.
7. Reagents and Standards
NOTE: Unless otherwise indicated, all references to water should be understood to mean Type I Reagent
water (ASTM D1193; see Reference 16.9).
NOTE: All reagents are American Chemical Society (ACS) grade or equivalent unless otherwise specified.
7.1. Sodium Carbonate, Na2CO3, anhydrous. Note that anhydrous sodium carbonate is to be
stored in a desiccator.
7.2. Potassium Carbonate, K2CO3, anhydrous. Note that anhydrous potassium carbonate is
to be stored in a desiccator.
7.3. Boric Acid, H3BO3. Stored in a desiccator to eliminate any moisture uptake.
7.4. Nitric Acid (8 M), HNO3. Carefully add 500 mL of concentrated nitric acid to about
500 mL of water.
7.5. Hydrofluoric acid (28M): Concentrated HF, available commercially.
7.6. Dry flux mix. Dry each reagent separately at 105 °C to remove moisture. Mix equal
weights of sodium carbonate, potassium carbonate and boric acid and store in a
desiccator.
7.7. Calcium carrier solution,100 mg/mL Ca: Dissolve 37.8 g of CaCl2»2H2O in 100 mL of
water
7.8. Na2CO3 solution, 2 M: Dissolve 212 g of dry Na2CO3 in 200 mL of water and dilute to
1 liter
7.9. Na2CO3 solution, 0.05 M: Dissolve 5.3 g of Na2CO3 in 1 L of water
7.10. NaOH solution, 10 M: 40 g of NaOH in 100 mL of water
7.11. Phenolphthalein
7.12. Radioactive tracers/carriers (used as yield monitors) and spiking solutions. Refer to the
strontium in water method (see Reference 16.5)
NOTE: In those samples where native constituents are present that could interfere with the
determination of the chemical yield (e.g., strontium for 90Sr analysis) 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.
8. Sample Collection, Preservation, and Storage
Not Applicable.
9. Quality Control
9.1. Where the subsequent chemical separation technique requires the addition of carriers
and radioactive tracers for chemical yield determinations, these are to be added prior to
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Rapid Method for Sodium Carbonate Fusion of Soil and Soil Related Matrices Prior to Strontium-90 Analysis
beginning the fusion procedure (or prior to charring of organic matter when applicable),
unless there is good technical justification for doing otherwise.
9.2. Batch quality control results shall be evaluated and meet applicable analytical project
specifications (APS) prior to release of unqualified data. In the absence of project-
defined APS or a project-specific quality assurance project plan (QAPP), the quality
control sample acceptance criteria defined in the laboratory's Quality Manual and
procedures shall be used to determine acceptable performance for this method.
9.2.1. An exception to this may need to be taken for samples of exceptionally high
activity where human safety may be involved.
9.3. Quality Control samples are generally specified in the laboratory's Quality Manual or
in a project's analytical protocol specifications. At the very minimum the following are
suggested:
9.3.1. A laboratory control sample (LCS), which consists solely of the reagents used in
this procedure and a known quantity of radionuclide spiking solution, shall be
run with each batch of samples. The concentration of the LCS should be at or
near the action level or level of interest for the project.
9.3.2. One reagent blank shall be run with each batch of samples. The reagent blank
should consist solely of the reagents used in this procedure (including tracer or
carrier from the analytical method added prior to the fusion process).
9.3.3. A sample duplicate that is equal in size to the original aliquant should be
analyzed with each batch of samples. This provides assurance that the
laboratory's sample size reduction and sub-sampling processes are reproducible.
10. Calibration and Standardization.
10.1. Refer to the individual chemical separation and analysis methods for calibration and
standardization protocols.
11. Procedure
11.1. In accordance with the DQOs and sample processing requirements stated in the
project plan documents remove extraneous materials from the soil using clean forceps
or tweezers.
11.2. Samples should be heated in an oven at 105 °C until dry (i.e., constant weight).
11.3. Homogenize the sample so that a representative finely ground sample aliquant can be
removed.
11.4. Weigh 2-g aliquants into separate crucibles. Add 5.0 mg of strontium carrier being
used to each of the sample aliquants in the batch.
11.5. For samples containing sufficient organic matter to cause concerns with the
subsequent fusion process, the samples should be further heated in a muffle furnace
with temperature programming (using temperature hold points to ensure sample
ignition does not occur) up to 600 °C to ensure combustion of all organic matter.
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NOTE: Combustion of the organic matter in the sample can usually be accomplished over the
course of 1-2 hours for 1-g samples of soil where the material is spread into a thin layer (up to
about 0.4 cm thick).
11.6. Add 30 mL of concentrated hydrofluoric acid and evaporate to dryness on a hotplate
at medium to high heat (-300 °C). The evaporation should be complete in
approximately 90 minutes.
11.7. Add 6 g of dry flux mix (Step 7.6).
11.8. Warm the crucible slowly over the low flame of a Meeker or Fisher blast burner. The
initial heating may produce a vigorous reaction, which may last approximately 5
minutes. The crucible may be held over the flame with tongs or supported on a ring
stand with a ceramic triangle.
11.9. After the initial reaction has subsided, increase the heat gradually over 5 minutes until
the burner is at full flame.
11.10. Heat until the crucible glows bright red.
11.11. Continue heating over full flame for 5 minutes until no visible reaction is observed
and the melt is completely liquid and homogeneous.
11.12. Remove the crucible from the flame and swirl the contents so that the melt solidifies
on the sides of the crucible, approximately half-way up the sides. This will facilitate
the rapid dissolution of the cooled melt.
11.13. The crucible should be allowed to cool to the point so that addition of 8 M HNOs will
not create a violent reaction. Usually this is cool enough to touch.
11.14. When the crucible is moderately cool carefully add approximately 10 mL 8 M HNOs
by using a clean transfer pipette to wash the solid fusion cake down the inside walls
of the crucible. The reaction of the acid with the fused carbonate material may be
vigorous and care must be taken to avoid frothing the sample over the top of the
crucible. It may be necessary to place a lid on the crucible during the acid reaction to
avoid sample cross-contamination.
11.15. If necessary, heat the crucible gently on a hotplate and occasionally swirl the sample
to facilitate the dissolution of the fusion cake. Ensure that the entire fusion cake is
dissolved and that no solid material remains on the sides of the crucible.
11.16. If necessary, add additional 8 M HNCb in small (~ 1 mL) increments to facilitate the
complete dissolution of the fusion cake.
11.17. Transfer the dissolved sample to an appropriately sized beaker, rinsing the crucible
with 8 M HNOs to ensure a quantitative transfer of material.
11.18. Add 1 mL of 100 mg/mL calcium to the diluted, dissolved fusion cake
11.19. Add ~ 0.5 mL of 0.1% phenolphthalein indicator and adjust pHto > 8.3 by adding 10
M NaOH while stirring continuously. The sample will become pinkish-orange due to
the indicator color change and the formation of hydroxide precipitate.
11.20. Add 30 mL of 2 M Na2CO3. Heat and stir for ~ 30 minutes.
11.21. Remove from heat and allow precipitate to settle for at least 30 minutes.
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11.22. Decant supernatant and transfer precipitate to 50 mL centrifuge tube.
11.23. Rinse precipitate with 40 mL of 0.05 M Na2CC>3. Re-suspend the precipitate in the
0.05 M Na2CC>3 then centrifuge and decant.
11.24. Dissolve precipitate with 4 mL of concentrated HNOs. Add water to bring volume to
8 mL. This is the column load solution (nitrate concentration is ~ 8 M). If more
concentrated HNOs is needed to dissolve a larger precipitate add water to bring the
volume to twice the volume of the added acid.
11.25. Perform strontium resin separation as described in "Rapid Radiochemical Method for
Total Radiostrontium (Sr-90) in Water for Environmental Restoration Following
Homeland Security Events" (see Reference 16.5) beginning at Step 11.11 (the load
solution is the solution produced in Step 17 above).
NOTE: Step 11.19.3 of the rapid water method for strontium-90 (see Reference 16.5) describes
evaporation of the strontium eluate on a hotplate or under a heat lamp. Evaporation of the
eluate should be done on a hotplate set at ~ 300 °C (digital display) in order to determine
gravimetric chemical yields accurately. Initial drying is done at ~ 180 °C to avoid spattering and
then the temperature is increased to ~ 300 °C for about 15 minutes.
11.26. Continue following the rapid water method for strontium-90 (Reference 16.5) to
prepare sample test source, count, and perform data analysis and calculations.
12. Data Analysis and Calculations
12.1. Equations for determination of final result, combined standard uncertainty and
radiochemical yield (if required) are found in the corresponding chemical separation
and analysis methods, with the exception that the sample size is calculated as
described below, with the units being provided by the incident command, rather than
liters of water.
12.2. In cases where samples have elevated activity, aliquants should be removed carefully,
first measuring the mass or volume of the entire final digestate. The mass or volume
of the aliquants removed must also be carefully measured to ensure that the sample
aliquant size used for analysis is accurately determined. The creation of multiple
aliquants of a sample should be thoroughly documented and reported in the case
narrative.
For a single split the effective size of sample is calculated:
v a s Y) Equation 1
Where:
Vs = original sample size, in the units designated by the incident command
(e.g., 1 g, etc.)
Ds = mass or volume of the entire final digestate, created in Step 11.13 of this
procedure (e.g., 100 g, 50 mL, etc.).
Da = mass or volume of the aliquant of digestate used for the individual
analyses, as described in the various parts of Step 11.14-11.17 of this
procedure (e.g., 25 g, 5.0 mL, etc.). Note that the values for Da must be in
the same units used in Ds.
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Va = sample aliquant size, used for analysis, in the units designated by the
incident command (e.g., kg, g, etc.).
NOTE: For higher activity samples, additional dilution may be needed. In such cases, Equation 1
should be modified to reflect the number of splits and dilutions performed. It is also important to
measure the masses or volumes, used for aliquanting or dilution, to enough significant figures so
that their uncertainties have an insignificant impact on the final uncertainty budget.
12.2.1. In cases where the sample will not be split prior to analysis, the sample aliquant
size is simply equal to the original sample size, in the same units requested by
the incident commander.
13. Method Performance
13.1. Method validation results should be archived by the laboratory.
13.2. Expected turnaround time per sample.
13.2.1. For representative, finely ground, 1-g aliquant of dried sample where
combustion to remove organic^ is required, combustion of the sample and the
subsequent fusion should add approximately 5 hours per batch to the time
specified in the individual chemical separation methods.
13.2.2. In some cases, it may not be necessary to perform combustion to remove
organic matter. For representative, finely ground, 1-g aliquant of dried sample
where combustion to remove organics is not required, the fusion should add
approximately 2 hours per batch to the time specified in the individual chemical
separation methods.
NOTE: Turnaround times for the subsequent chemical separation methods are given in those
methods for batch preparations.
14. Pollution Prevention
With the exception of minute quantities of combustion products, this method inherently
produces no significant pollutants. The sample and fusion reagents are retained in the final
product and are carried into the ensuing chemical separation techniques, which marginally
increases the salt content of the effluent waste. It is noted that if the sampled particulates
include radionuclides which may be volatile under the fusion conditions, these constituents
will be exhausted through fume hood system.
15. Waste Management
15.1. Refer to the appropriate chemical separation methods for waste disposal information.
16. References
16.1. U.S. Environmental Protection Agency (EPA). 2009. Method Validation Guide for
Qualifying Methods Used by Radiological Laboratories Participating in Incident
Response Activities. Revision 0. Office of Air and Radiation, Washington, DC. EPA
402-R-09-006, June. Available at: www.epa.gov/narel/incident guides.html.
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Rapid Method for Sodium Carbonate Fusion of Soil and Soil Related Matrices Prior to Strontium-90 Analysis
16.2. U.S. Environmental Protection Agency (EPA). 2012. Rapid Method for Sodium
Carbonate Fusion of Soil and Soil-Related Matrices Prior to Americium, Plutonium,
and Uranium Analyses for Environmental Remediation Following Radiological.
Revision 0. Office of Air and Radiation, National Air and Radiation Environmental
Laboratory. Available at: www.epa.gov/narel/incident_guides.html.
16.3. U.S. Environmental Protection Agency (EPA). 2012. Rapid Method for Radium in Soil
Incorporating the Fusion of Soil and Soil-Related Matrices with the Radioanalytical
Counting Method for Environmental Remediation Following Radiological Incidents.
Revision 0. Office of Air and Radiation, National Air and Radiation Environmental
Laboratory. Available at: www.epa.gov/narel/incident guides.html.
16.4. U.S. Environmental Protection Agency (EPA). 2012. Radiological Sample Analysis
Guide for Incident Response — Radionuclides in Soil. Revision 0. Office of Air and
Radiation, Washington, DC. EPA 402-R-12-006, September. Available at:
www.epa.gov/narel/incident guides.html.
16.5. MARLAP. 2004. Multi-Agency Radiological Laboratory Analytical Protocols Manual.
Volumes 1-3. Washington, DC: EPA 402-B-04-001A-C, NUREG 1576, NTIS
PB2004-105421. July. Available at: www.epa.gov/radiation/marlap/.
16.6. U.S. Environmental Protection Agency (EPA). 2010. "Radiostrontium (Sr-90) in
Water: Rapid Method for High-Activity Samples." Revision 0. In, Rapid Radiochemical
Methods for Selected Radionuclides in Water for Environmental Restoration Following
Homeland Security Events, EPA 402-R-10-001, February. Office of Air and Radiation,
National Air and Radiation Environmental Laboratory. Revision 0.1 of rapid methods
issued October 2011. Available at: www.epa.gov/narel/incident_guides.html.
16.7. U.S. Environmental Protection Agency (EPA). 2012. "Rapid Method for Sodium
Hydroxide Fusion of Concrete Matrices Prior to Am, Pu, Sr, Ra, and U Analyses. "
Revision 0. Office of Air and Radiation, National Air and Radiation Environmental
Laboratory. Available at: www.epa.gov/narel/incident_guides.html.
16.8. U.S. Environmental Protection Agency (EPA). 2012. "Rapid Radiochemical Method
for Total Radiostrontium (Sr-90) in Building Materials for Environmental Remediation
Following Radiological Incidents." Revision 0. Office of Air and Radiation, National
Air and Radiation Environmental Laboratory. Available at:
www.epa.gov/narel/incident guides.html.
16.9. ASTM Dl 193, "Standard Specification for Reagent Water" ASTM Book of Standards
11.01, current version, ASTM International, West Conshohocken, PA.
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17. Flowchart
17.1. Flow Chart for Separation
Steps 11.1-11.3
Remove detritus,
add tracer, dry,
homogenize, and
aliquant
Step 11.4
Add Sr carrier
Step 11.5
Muffle combustion
needed?
Combustion
at600°C
Step 11.6
Digestwith HF
and evaporate to
dryness
Steps 11.7-11.13
Fusion using
Na2C03
Steps 11.14-11.17
Dissolve fused
cake using 3 M
nitric acid
v
Steps 11.18-11.24
Add Ca, re-
precipitate SrC03,
re-dissolve in nitric
acid
Proceed to the
Rapid Method for
Strontium in
Water, Step 11.11,
load solution for
separation
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Appendix A:
Rapid Technique for Milling and Homogenizing Soil Samples
Al. Scope and Application
ALL The method describes one approach for the rapid, gross preparation of soil samples
to yield dried, representative 1-2-g aliquant for radiochemical analysis of non-
volatile radionuclides. The method addresses steps for splitting, drying, and milling
of 50-2,000-g soil samples.
Al .2. This rapid milling method is designed to be used as a preparatory step for the
fusion of soils for Am, Pu, U, 90Sr, and 226Ra. It may also be applied to other
matrices whose physical form is amenable to pulverization in the ball mill. It is not
amenable to radionuclides that are volatile at 110 °C or below.
A1.3. The use of the term soil is not intended to be limiting or prescriptive. The method
described applies to soil-related materials such as sand, humic/fulvic soils, peat,
loam, sediment, etc.
Al .4. If the levels of activity in the sample are low enough to permit safe radiological
operations, up to 2 kg of soil can be processed.
A2. Summary of Method
A2.1. This method uses only disposable equipment to contact the sample minimizing the
risk of contamination and cross-contamination and eliminating concerns about
adequate cleaning of equipment.
A2.2. Extraneous material, such as vegetation, biota, or rocks or debris may be removed
prior to processing the sample unless the project requires that they be processed as
part of the sample.
NOTE: The sample mass is generally used for measuring the size of solid samples. The initial
process of acquiring a representative aliquant uses the volume of the sample, as the total
sample size is generally based on a certain volume of soil (e.g., 500 mL).
A2.3. The entire sample as received is split by coning and quartering until -75-150 mL of
soil are available for subsequent processing. If less than -450 mL of soil are
received, the entire sample is processed.
A2.4. The soil is transferred to a paint can and dried. Percent solids are determined, if
required.
A2.5. Grinding media (stainless-steel or ceramic balls or rods) are added, and the sample
is milled to produce a finely-ground, well-homogenized, powder with predominant
particle size less than 300 um.
A2.6. If the sample may contain discreet radioactive particles (DRPs), particles larger
than a nominal size of 150 um are screened for radioactivity, and further milled, or
processed with another appropriate method to ensure that they will be chemically
available for subsequent processing.
A2.7. The resulting milled sample is stored in, and aliquanted directly from, the container
used for drying and pulverization.
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A3. Definitions, Abbreviations, and Acronyms
A3.1. Discrete Radioactive Particles (DRPs or "hot particles"). Particulate matter in a
sample of any matrix where a high concentration of radioactive material is
contained in a tiny particle (um range).
A3.2. Multi-Agency Radiological Analytical Laboratory Protocol (MARLAP) Manual
(see Reference 16.8).
A4. Interferences
A4.1. Radi ol ogi cal Interference s
A4.1.1. Coning and quartering provides a mechanism for rapidly decreasing the
overall size of the sample that must be processed while optimizing the
representativeness of the subsampling process. By decreasing the time
and effort needed to prepare the sample for subsequent processing,
sample throughput can be significantly improved. Openly handling large
amounts of highly contaminated materials, however, even within the
containment provided by a fume hood, may pose an unacceptable risk of
inhalation of airborne contamination and exposure to laboratory
personnel from radioactive or other hazardous materials. Similarly, it
may unacceptably increase the risk of contamination of the laboratory.
A4.1.2. In such cases, coning and quartering process may be eliminated in lieu
of processing the entire sample. The time needed to dry the sample will
increase significantly, and the container size and the number and size of
grinding media used will need to be adjusted to optimize the milling
process. See ASTM C999 (see Reference A16.3) for an approach for
homogenization and milling of larger soil samples.
A4.2. The precise particle size of the milled sample is not critical to subsequent
processes. However, milling the sample to smaller particle sizes, and thorough
mixing, both facilitate representative sub-sampling by minimizing the amount of
sample that is not pulverized to fine mesh and must be discarded. Additionally,
subsequent fusion and digestion processes are more effective when performed on
more finely milled samples.
A4.3. This method assumes that radioactivity in the sample is primarily adsorbed onto the
surface of particles, as opposed to being present as a hot particle (see discussion of
DRPs below). Thus, nearly all of the activity in a sample will be associated with
sample fines. By visually comparing the sample to a qualitative standard of -50-
100 mesh size particles, it is possible to rapidly determine whether the sample is
fine enough to facilitate the subsequent fusion or digestion. This method assumes
that when greater than 95% of the sample is as fine or finer than the 50-100 mesh
sample, bias imparted from losses of larger particles will be minimal.
A4.4. If the sample was collected near the epicenter of an radiological dispersal device
(RDD) or improvised nuclear device (IND) explosion, it may contain millimeter- to
micrometer-sized particles of contaminant referred to as "discrete radioactive
particles," or DRPs. DRPs may consist of small pieces of the original radioactive
source and thus may have very high specific activity. They may also consist of
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chemically intractable material and present special challenges in the analytical
process. Even when size reduced to less than 50-100 mesh, these particles may
resist fusion or digestion of the solids into ionic form which can be subjected to
chemical separations.
A4.5. When DRPs may be present, this method isolates larger particles by passing the
sample through a disposable 50 mesh screen after which they can be reliably
checked for radioactivity. DRPs may reliably be identified by their very high
specific activity which is readily detectable since they show high count rates using
hand-held survey equipment such as a thin-window Geiger-Muller (G-M) probe.
A4.6. When present, DRPs may be further milled and then recombined with the original
sample. Alternatively, the particles, or the entire sample may need to be processed
using a different method capable of completely solubilizing the contaminants such
that the radionuclides they contain are available for subsequent chemical
separation.
A5. Safety
A5.1. General
A5.1.1. Refer to your safety manual for concerns of contamination control,
personal exposure monitoring and radiation dose monitoring.
A5.1.2. Refer to the laboratory chemical hygiene plan for general chemical
safety rules
A5.2. Radiological
A5.2.1. Refer to your radiation safety manual for direct on working with known
or suspected radioactive materials.
A5.2.2. This method has the potential to generate airborne radioactive
contamination. The process should be carefully evaluated to ensure that
airborne contamination is maintained at acceptable levels. This should
take into account the activity level, and physical and chemical form of
contaminants possibly present, as well as other engineering and
administrative controls available.
A5.2.3. Hot Particles (DRPs)
A5.2.3.1. Hot particles will usually be small, on the order of 1 mm or
less. Typically, DRPs are not evenly distributed in the media,
and their radiation emissions are not uniform in all directions
(anisotropic). Filtration using a 0.45-um filter or smaller may
be needed following subsequent fusion to identify the
presence of smaller DRPs.
A5.2.3.2. Care should be taken to provide suitable containment for
filter media used in the pretreatment of samples that may
have DRPs, because the particles become highly statically
charged as they dry out and will "jump" to other surfaces
potentially creating contamination-control issues.
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A5.3. Method-Specific Non-Radiological Hazards
A5.3.1. This method employs a mechanical shaker and should be evaluated for
personnel hazards associated with the high kinetic energy associated
with the milling process.
A5.3.2. This method employs a mechanical shaker and involves vigorous
agitation of steel or ceramic balls inside steel cans. The process should
be evaluated to determine whether hearing protection is needed to
protect the hearing of personnel present in the area in which the
apparatus is operated.
A6. Equipment and supplies
A6.1. Balance, top-loading, range to accommodate sample size encountered, readability
to ±1%.
A6.2. Drying oven, at 110±10 °C.
A6.3. Steel paint cans and lids (pint, quart, 2-quart, 1-gallon, as needed).
A6.4. Steel or ceramic grinding balls or rods for ball milling, ~15-mm diameter. The size
and number of grinding media used should be optimized to suit the types of sand or
soil, the size of the can, and the volume of soil processed.
A6.5. Wire cloth - nominal 48 mesh size (-300 um).
A6.6. Sieves, U.S. Series No. 50 (300-um or 48 mesh) and U.S. Series No. 100 (ISO-pin
or 100 mesh).
A6.7. Red Devil 5400 mechanical paint shaker, or equivalent mechanical.
A6.8. Disposable scoop, scraper, tongue depressor or equivalent.
A7. Reagents and Standards
No reagents needed.
A8. Sample Collection, Preservation and Storage
A8.1. Samples should be collected in appropriately sized plastic, metal or glass
containers.
A8.2. No sample preservation is required. If samples are to be held for an extended period
of time, refrigeration may help minimize bacterial growth in the sample.
A8.3. Default sample collection protocols generally provide solid sample volumes
equivalent to approximately 500 mL of sample. Such samples will require two
splits to obtain a -100 mL sample.
A9. Quality Control
A9.1. Batch quality control results shall be evaluated and meet applicable Analytical
Project Specifications (APS) prior to release of unqualified data. In the absence of
project-defined APS or a project-specific quality assurance project plan (QAPP),
the quality control sample acceptance criteria defined in the laboratory quality
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manual and procedures shall be used to determine acceptable performance for this
method.
A9.2. Quality control samples should be initiated as early in the process as possible.
Since the risk of cross-contamination using this process is relatively low, initiating
blanks and laboratory control samples at the start of the chemical separation
process is acceptable. If sufficient sample is available, a duplicate sample should be
prepared from the two discarded quarters of the final split of the coning and
quartering procedure.
A10. Procedure
NOTE: This method ensures that only disposable equipment comes in contact with sample materials to
greatly minimize the risk sample cross-contamination and concerns about adequate cleaning of
equipment.
A10.1. Estimate the total volume of sample, as received.
If the sample is dry, the risk of resuspension and inhalation of the solids may be determined
to be unacceptable. In such cases, the entire sample may be processed in a larger can. The
drying and milling time will be increased, and more grinding media will be required to obtain
a satisfactory result
The next step uses absorbent paper in the reverse fashion for the normal use of this type of
paper; it allows for a smooth division of the sample and control of contamination.
Al 0.1.1. Spread a large piece of plastic backed absorbent paper, plastic side up in
a hood.
A10.1.2. If the sample volume is less than -450 mL, there is no benefit to coning
and quartering.
A10.1.2.1. Carefully pour the sample onto the paper.
A10.1.2.2. Remove extraneous material, such as vegetation, biota, or
rocks or debris unless the project requires that such material
be processed as part of the sample. Continue with Step
A10.1.6.
A10.1.2.3. If the sample volume is greater than -450 mL, carefully pour
the entire sample into a cone onto the paper.
Remove extraneous material, such as vegetation, biota, or
rocks or debris unless the project requires that such material
be processed as part of the sample.
A10.1.3. If levels of gross activity in the sample permit, the sample is split at
least twice using the coning and quartering steps that follow.
NOTE: Unused quarters are considered representative of the original sample and
may be reserved for additional testing. The process should be carried out
expediently to minimize loss of volatile components in the sample, especially
volatile components or percent solids are to be determined.
See IUPAC Gold Book, Coning and Quartering in Analytical Chemistry, available at:
goldbook.iupac.org/C01265.html
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A10.1.4. Spread the material into a flat circular cake of soil using a tongue
depressor or other suitable disposable implement. Divide the cake
radially and return two opposing quarters to the original sample
container.
A10.1.5. Reshape the remaining two quarters into a smaller cone, and repeat Step
A10.1.3 until the total volume of the remaining material is
approximately 100-150 mL.
NOTE: Tare the can and lid together. Do not apply an adhesive label rather label
the can with permanent marker since the can will be placed in a drying oven. The
lid should be labeled separately since it will be removed from the can during
drying
A10.1.6. Transfer the coned and quartered sample to a tared and labeled 1-pint
paint can. If the total volume was less than -450 mL, transfer the entire
sample to a tared and labeled 1-quart paint can.
NOTE: Constant mass may be determined by removing the container from the
oven and weighing repeatedly until the mass remains constant with within 1% of
the starting mass of the sample. This may also be achieved operationally by
observing the time needed to ensure that 99% of all samples will obtain constant
mass.
A10.2. Place the can (without lid) in an oven at 110 ± 10 °C and dry the soil to constant
mass.
A10.3. Weigh the combined mass of the can, sample, and lid. If the percent solids are
required see Step A12.1 calculations.
A10.4. Add five 1.5-cm stainless-steel or ceramic balls or rods to the can. Replace the lid
and seal well.
A10.5. Shake the can and contents for 5-15 minutes, or longer, as needed to produce a
finely-milled, well-homogenized, sample.
NOTE: Although the precise particle size of the milled sample is not critical, complete
pulverization and fine particle size facilitates representative sub-sampling and subsequent
fusion or digestion processes. A qualitative standard can be prepared by passing quartz sand
or other milled material through a 50-mesh and then a 100-mesh screen. The portion of the
sample retained in the 100 mesh screen can be used as a qualitative visual standard to
determine if samples have been adequately pulverized.
A10.6. Visually compare the resulting milled sample to a qualitative 50-100 mesh
pulverized sample (~150-300-um or 50-100 mesh using the Tyler screen scale).
The process is complete once 95% of the sample (or greater) is as fine, or finer,
than the qualitative standard. If, by visual estimation, more than -5% of total
volume of the particles in the sample appear to be larger than the particle size in the
standard, return the sample to the shaker and continue milling until the process is
complete.
A10.7. Following milling, a small fraction of residual larger particles may remain in the
sample.
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A10.7.1. If the sample was collected close to the epicenter of an RDD or IND
explosion, it may also contain particles of contaminant referred to as
"discrete radioactive particles" or DRPs. In such a case, the larger
particles should be isolated by passing through a disposable 48 mesh
screen and checked for radioactivity. DRPs are readily identified by
their very high specific activity which is detectable using hand-held
survey equipment such as a thin-window G-M probe held within an inch
of the particles.
A10.7.1.1. If radioactivity is clearly detected, the sieved material is
returned to the can and ball milled until the desired mesh is
obtained. In some cases, these materials may be resistant to
further pulverization and may need to be processed
according to a method specially designed to address highly
intractable solids.
A10.7.1.2. If the presence of DRPs is of no concern, the larger particles
need not be included in subsequent subsamples taken for
analysis. It may be possible to easily avoid including them
during aliquanting with a disposable scoop. If not, however,
they should be removed by sieving through a nominal 50
mesh screen (disposable) prior to further subsampling for
subsequent analyses.
A10.8. Sample fines may be stored in, and aliquanted directly from, the container used for
drying and pulverization.
All. Calibration and Standardization
Balances used shall be calibrated using National Institute of Standards and Technology
(NIST)-traceable weight according to the process defined by the laboratory's quality
manual.
A12. Data Analysis and Calculations
A12.1. The percent solids (dry-to-as-received mass ratio) for each sample is calculated
from data obtained during the preparation of the sample as follows:
% Solids = Mdiy'Mtare x 100
"^-asrec " -'-"tare
Where:
= mass of dry sample + labeled can + lid (g)
= tare mass of labeled can + lid (g)
= mass of sample as received + labeled can + lid (g)
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A12.2. If requested, convert the equivalent mass of sample, as received, to dry mass as
follows:
% Solids
Dry SampleEquivalent = Mtotal.asrec x — — —
Where:
i-as rec.
c. = total mass of sample, as received (g)
A 12. 3. Results Reporting
The result for percent solids and the approximate total mass of sample as received
should generally be reported for each result.
A13. Method Performance
A13.1. Results of method validation performance are to be archived and available for
reporting purposes.
A13.2. Expected turnaround time is about 3 hours for an individual sample and about 4
hours per batch.
A14. Pollution Prevention.
Not applicable.
A15. Waste Management.
All radioactive and other regulated wastes shall be handled according to prevailing
regulations.
A16. References
A16.1. A. D. McNaught and A. Wilkinson, Coning and Quartering in Analytical
Chemistry, IUPAC Compendium of Chemical Terminology, The Gold Book,
Second Edition, Blackwell Science, 1997 (online edition).
A16.2. ALS Environmental, Fort Collins, SOP 736.
A16.3. ASTM C 999-05, Standard Practice for Soil Sample Preparation for the
Determination of Radionuclides, Volume 12.01, ASTM, 2005.
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A17. Tables, Diagrams, and Flow Charts
A17.1. Homogenization
Steps A10.1.1-A10.1.2
Estimate Sample volume,
remove detritus
StepsA10.2-A10.3
Dry at 110 °C to constant
mass
StepAlO.1.3
Cone and quarter, transfer
aliquantto tared container
StepsA10.-A10.5
Add ceramic or steel balls
and mix
Steps 10.6-A10.7 Visual
inspection for homogeneity
and particle size
StepAlO.8
Aliquant sample and store
residual
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