www.epa.gov/radiation
May 2017
EPA 402-S17-001
Revision 0
Rapid Radiochemical Method for Curium-
244 in Water Samples for Environmental
Remediation Following Radiological
Incidents
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Radiation and Indoor Air
National Analytical Radiation Environmental Laboratory
Montgomery, AL 36115
Office of Research and Development
National Homeland Security Research Center
Cincinnati, OH 45268
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Rapid Radiochemical Method for Curium-244 in Air Particulate Filters, Swipes and Soils
Revision History
Revision 0 Original release. 05-01-2016
This report was prepared for the National Analytical Radiation Environmental Laboratory of the Office of
Radiation and Indoor Air and the National Homeland Security Research Center of the U.S. Environmental
Protection Agency's (EPA) Office of Research and Development. It was prepared by Environmental
Management Support, Inc., of Silver Spring, Maryland, under contract EP-W-13-016, task order 014,
managed by Dan Askren. This document has been reviewed in accordance with EPA policy and approved
for publication. Note that approval does not signify that the contents necessarily reflect the views of the
Agency. Mention of trade names, products, or services does not convey EPA approval, endorsement, or
recommendation.
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Rapid Radiochemical Method for Curium-244 in Water Samples
Rapid Radiochemical Method for Cm-244 in Water Samples for
Environmental Remediation Following Radiological Incidents
1. Scope and Application
1.1. This method provides for the rapid determination of 244Cm in water samples.
1.2. The method uses radiochemical separation techniques to rapidly isolate curium from a
243
water matrix using Am tracer as a yield monitor.
1.3. A sample test source is prepared by microprecipitation. The test source is counted by
alpha spectrometry for 244Cm.
1.3.1. Cm-243 emits alpha particles that are isoenergetic with 244Cm. Alpha
spectrometry measurements that show activity in the region of interest for
2 4Cm should be reported as 244/243Cm.
1.4. This method is capable of achieving a required method uncertainty for 244Cm of 2.0
pCi/L at an analytical action level of 15 pCi/L. To attain the stated measurement
quality objectives (MQOs), a sample volume of approximately 0.2 L and count time
of at least 4 hours are recommended. Sample count times may vary based on
differences in instrument parameters such as detection efficiency and background.
1.5. The 244Cm method was single-laboratory evaluated following the guidance presented
for "Level E Method Validation: Adapted or Newly Developed Methods, Including
rapid methods" in Method Validation Guide for Qualifying Methods Used by
Radiological Laboratories Participating in Incident Response Activities (Reference
16.1) and Chapter 6 of the Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP, Reference 16.2).
1.5.1. Since californium and americium track closely with curium through the
chemical separation, it may be possible to determine isotopes of
241
californium, as well as isotopes of americium (e.g., Am) that may be
present in the sample test source. The specific method performance (yield,
required method uncertainty [«mr], minimum detectable activity, and critical
level) for other isotopes of californium, americium, or curium (e.g., 249Cf
241 Am, or 244/243Cm must be validated by the laboratory prior to performing
determinations for these radionuclides).
1.5.2. The sample turnaround time and throughput may vary based on additional
project MQOs, the time for analysis of the sample test source, and initial
sample weight / volume.
1.5.3. The method must be validated prior to use following the protocols provided
in Method Validation Guide for Qualifying Methods Used by Radiological
Laboratories Participating in Incident Response Activities (Reference 16.1).
2. Summary of Method
2.1. This method is based on the use of extraction chromatography resins (TEVA® + DGA
Resins) to isolate and purify curium by removing interfering radionuclides and other
matrix components and prepare the curium fraction for counting by alpha
spectrometry. The method utilizes vacuum-assisted flow to improve the speed of the
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Rapid Radiochemical Method for Curium-244 in Water Samples
243
separations. An Am tracer is equilibrated with the water sample and used as a yield
monitor. Following chemical separation of Cm and Am, the sample test source (STS)
is prepared by microprecipitation with cerium fluoride (CeF3). The alpha emissions
from the source are measured using an alpha spectrometer and used to calculate the
activity of 244Cm in the sample.
3. Definitions, Abbreviations, and Acronyms
3.1. Analytical Protocol Specifications (APS). The output of a directed planning process
that contains the project's analytical data needs and requirements in an organized,
concise form.
3.2. Analytical Action Level (AAL). The term "analytical action level" is used to denote
the value of a quantity that will cause the decision-maker to choose one of the
alternative actions.
3.3. 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 (|im range).
3.4. Multi-Agency Radiological Analytical Laboratory Protocols Manual (MARLAP)
provides guidance for the planning, implementation, and assessment phases of those
projects that require the laboratory analysis of radionuclides (Reference 16.2).
3.5. Measurement Quality Objective (MQO). MQOs are the analytical data requirements of
the data quality objectives and are project- or program-specific. They can be
quantitative or qualitative. MQOs serve as measurement performance criteria or
objectives of the analytical process.
3.6. Required Method Uncertainty (wMr)- The required method uncertainty is a target value
for the individual measurement uncertainties and an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method
uncertainty is applicable below an AAL.
3.7. Required Relative Method Uncertainty ((Pmr). The required relative method uncertainty
is the wmr divided by the AAL and is typically expressed as a percentage. It is
applicable above the AAL.
3.8. Sample Test Source (STS). This is the final form of the sample that is used for nuclear
counting. This form is usually specific for the nuclear counting technique used in the
method such as a solid deposited on a filter for alpha spectrometry analysis.
4. Interferences
4.1. Radiological
4.1.1. The alpha emissions from 243Cm fall in the same region as 244Cm and cannot
be differentiated from those of 244Cm using alpha spectrometric
determinations.
4.1.1.1. Although the 244Cm and 243Cm alpha emissions overlap,
monitoring the region of the spectrum between 5.8 and 6.0 MeV
for less intense emissions of 2 3Cm may qualitatively indicate the
presence of 243Cm in a sample.
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Rapid Radiochemical Method for Curium-244 in Water Samples
4.1.1.2. Alpha spectrometry measurements that show activity in the region
of interest for 244Cm should be reported as 244/243Cm.
4.1.2. Americium and californium are chemical analogs of curium in the
separations scheme used for this analysis. Several isotopes of californium or
americium emit alpha particles within the region of interest for 244Cm. These
249 251
include Cf and Cf. If high levels of californium could be present in
samples, alpha spectrometry results should be monitored for other isotopes
of californium.
4.1.3. Americium 243 may be present in certain sources that contain 244Cm. In
243 241
cases where Am is observed or suspected to be present in samples, Am
243
may be used in place of Am as the yield tracer. Although there is no
reason to expect different performance, the approach should be validated by
the laboratory prior to implementing.
4.1.4. Radionuclides of other elements (or their short-lived progeny) that emit
alpha particles that are isoenergetic with 244Cm (e.g., 27Th or 225Ac at 5.8
MeV) must be chemically separated to prevent positive interference with the
measurement. This method separates these radionuclides effectively. For
example, a thorium removal rinse is performed on DGA Resin in the event
that thorium passes through TEVA® Resin onto DGA Resin.
4.1.5. Curium present as a solid (e.g., in DRPs) will not be chemically available
and will not be determined unless it is dissolved prior to chemical
separation.
4.1.6. Vacuum box lid and holes should be cleaned frequently to prevent cross-
contamination of samples.
4.2. Non-Radiological:
4.2.1. Anions that can complex curium and americium, including fluoride and
phosphate, may lead to depressed yields. Aluminum in the load solution will
complex both fluoride and residual phosphate.
4.2.2. High levels of calcium can have an adverse impact on curium and
americium retention on DGA Resin. Calcium retention is minimized and
curium and americium affinity enhanced by increasing nitrate
concentrations in the load and initial rinse solutions. A dilute nitric acid
rinse is performed on DGA Resin to remove calcium that could otherwise
end up in the sample test source as the fluoride. For samples containing
elevated concentrations of calcium, it may be advisable to increase the
volume of this rinse step slightly to better remove calcium ions and possibly
improve alpha peak resolution. This modification must be validated by the
laboratory prior to use with samples.
5. Safety
5.1. General
5.1.1. Refer to your safety manual for concerns of contamination control, personal
exposure monitoring, and radiation dose monitoring.
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Rapid Radiochemical Method for Curium-244 in Water Samples
5.1.2. Refer to your laboratory's chemical hygiene plan (or equivalent) for general
safety rules regarding chemicals in the workplace.
5.2. Radiological
5.2.1. Hot particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles" (DRPs),
are small, usually much smaller than 1 mm. Typically, DRPs are
not evenly distributed in the media and their radiation emissions
are anisotropic (i.e., not uniform in all directions).
5.2.1.2. Samples containing measureable activity of 244Cm may have
DRPs. If suspended solids are removed by filtration, they may be
checked for potential radioactivity.
5.2.2. For samples with detectable activity concentrations of these radionuclides,
labware should be used only once due to potential for cross contamination.
5.3. Procedure-Specific Non-Radiological Hazards: Particular attention should be paid to
the use of hydrofluoric acid (HF). HF is an extremely dangerous chemical used in the
preparation of some of the reagents and in the microprecipitation procedure.
Appropriate personal protective equipment (PPE) must be used in strict accordance
with the laboratory safety program specification.
6. Equipment and Supplies
6.1. Alpha spectrometer calibrated for use over a range that at minimum includes 4.5 and
7.0 MeV.
_2
6.2. Analytical balance with minimum 10 g readability.
6.3. Centrifuge tubes, 225-milliliter (mL), 50-mL capacity, or equivalent.
6.4. Centrifuge, to accommodate centrifuge tubes.
6.5. Heat lamp.
6.6. Hot Plate.
6.7. Laboratory ware of plastic, glass, or Teflon; 150-, 250-, 500- and 1,000-mL capacities,
as needed.
6.8. Pipettor, electronic, and appropriate plastic tips, 1-10 mL as needed.
6.9. Pipettors and appropriate plastic tips, 100-microliter (|jL), 200-[xL, 500-[xL and 1-mL,
or equivalent, as needed.
6.10. Sample test source mounts:
6.10.1. Polypropylene filter, 0.1 micrometer ([j,m) pore size, 25-mm diameter, or
equivalent.
6.10.2. Stainless steel planchets, adhesive backed disks (e.g., Environmental
Express, Inc., Charleston, SC, part number R2200) or equivalent, calibrated
for 25-mm filter geometry.
6.11. Tweezers.
6.12. Vacuum box system
6.12.1. Vacuum box/rack (e.g., Eichrom Technologies, Inc., Lisle, IL, part number
AC-24-BOX), or equivalent.
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Rapid Radiochemical Method for Curium-244 in Water Samples
6.12.2. Cartridge reservoirs, 10 or 20 mL syringe style with locking device, or
columns (e.g., empty Luer-lock tip, Image Molding, Denver, CO part
number CC-10-M) plus 12 mL reservoirs (e.g., Image Molding, Denver,
CO, part number CC-06-M), or equivalent.
6.12.3. Vacuum box tips, white inner tubes, Eichrom Technologies, Inc., Lisle, IL,
part number AC-1000-TUBE-PE, or perfluoroalkoxy (PFA) 5/32" x y4"
heavy-wall tubing connectors, natural, Cole Parmer Instrument Company,
LLC, Vernon Hills, IL, part number 00070EE, cut to 1 inch, or equivalent.
6.12.4. Vacuum box tips, yellow outer, Eichrom Technologies, Inc., Lisle, IL, part
number AC-IOOO-OT, or equivalent.
6.12.5. Laboratory vacuum source.
6.13. Vortex mixer.
7. Reagents and Standards
Note: All reagents are American Chemical Society (ACS) reagent grade or equivalent unless otherwise
specified.
Note: Unless otherwise indicated, all references to water should be understood to mean Type I Reagent
water (ASTM D1193, Reference 16.4). All solutions used in microprecipitation should be prepared with
water filtered through a 0.45 jim (or better) filter.
Note: Low-levels of uranium are typically present in A1(N03)3.
7.1. Aluminum nitrate solution, 2 M: Add 750 g of aluminum nitrate (A1(N03)3 9 H20) to
-500 mL of water and dilute to 1 liter with water.
243
7.2. Americium-243 tracer solution: 10-40 disintegrations per minute (dpm) of Am per
aliquant.
7.3. Ammonium hydrogen phosphate, 3.2 M: Dissolve 106 g of (NH4)2HP04 in 200 mL of
water, heat gently to dissolve and dilute to 250 mL with water.
7.4. Ammonium hydroxide, 15 M: Concentrated NH4OH.
7.5. Ascorbic acid, 1.5 M: Dissolve 66 g CeHgOe in 200 mL of water, warming gently to
dissolve, and dilute to 250 mL with water. Shelf life is 30 days or less.
7.6. Calcium nitrate, 1.25 M: Dissolve 73.8 g of Ca(N03)2'4 H20 in 100 mL of water and
dilute to 250 mL with water.
7.7. Cerium carrier, 0.5 mg Ce/mL: dissolve 0.16 g Ce(N03)3' 6 H2O in 50 mL water and
dilute to 100 mL with water.
7.8. Curium-244 standard solution: 10-40 dpm of 244Cm per aliquant.
7.9. DGA Resin, normal, 2-mL cartridge, 50- to 100-|j,m mesh size, Eichrom Technologies,
Inc., Lisle, IL, part number DN-R50-S, or equivalent.
7.10. Ethanol, 95%: Reagent C2H5OH, or mix 95 mL 100% ethanol and 5 mL water.
7.11. Hydrochloric acid, 12 M: Concentrated HC1.
7.11.1. Hydrochloric acid, 0.25 M: Add 21 mL of concentrated HC1 to 500 mL of
water and dilute with water to 1 L.
7.11.2. Hydrochloric acid, 4 M: Add 333 mL of concentrated HC1 to 500 mL of
water and dilute with water to 1 L.
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Rapid Radiochemical Method for Curium-244 in Water Samples
7.12. Hydrofluoric acid, 28M: Concentrated HF
7.13. Hydrogen peroxide, 30 weight percent (wt. %) (H2O2).
7.14. Iron carrier, 4 mg/mL: Dissolve 14 g of ferric nitrate (Fe(NC>3)3 • 9 H2O) in 300 mL
water and dilute to 500 mL with water.
7.15. Nitric acid, 16 M: Concentrated HNO3.
7.15.1. Nitric acid, 0.1 M: Add 6.3 mL of concentrated HNO3 to 700 mL of water
and dilute to 1 L with water.
7.15.2. Nitric acid, 3 M: Add 190 mL of concentrated HNO3 to 700 mL of water
and dilute to 1 L with water.
7.15.3. Nitric acid, 6 M: Add 380 mL of concentrated HNO3 to 500 mL of water
and dilute to 1 L with water.
7.16. Nitric acid 3 M - Aluminum nitrate solution 1 M: Add equal volumes of 6 M HNO3
and2M A1(N03)3.
7.17. Nitric acid, 3 M - hydrofluoric acid, 0.25 M: Add 8.9 mL of concentrated HF and 190
mL of concentrated HNO3 to 700 mL of water. Dilute to 1 liter with water and mix
well.
7.18. Phenolphthalein indicator solution, 0.5 wt. % (C20H14O4): Dissolve 0.5 g in 100 mL
ethanol (95%).
7.19. Sodium nitrite solution, 3.5 M: Dissolve 6.1 g of NaNC>2 in 25 mL of water. Prepare
fresh daily.
7.20. Sulfamic acid solution, 1.5 M: Dissolve 72.8 g of H3NSO3 in 400 mL of water and
dilute to 500 mL with water.
7.21. TEVA® Resin, 2-mL cartridge, 50- to 100-|j,m mesh size, Eichrom Technologies, Inc.,
Lisle, IL, part number TE-R50-S and TE-R200-S, or equivalent.
8. Sample Collection, Preservation, and Storage
8.1. Water samples:
8.1.1. No sample preservation is needed if sample analysis is initiated within three
days of sample collection.
8.1.2. If sample analysis is not started within three days of sample collection, add
concentrated HN03 to achieve a pH<2 and then store for at least 16 hours prior
to analysis.
8.1.3. If the concentration of americium in the dissolved fraction is sought, the
insoluble fraction must be removed by filtration before preserving with acid.
9. Quality Control
9.1. Batch quality control results shall be evaluated and meet applicable Analytical
Protocol 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 manual
and procedures shall be used to determine acceptable performance for this method.
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Rapid Radiochemical Method for Curium-244 in Water Samples
9.1.1. A Laboratory Control Sample (LCS) 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.
9.1.2. One method blank shall be run with each batch of samples. The laboratory
blank should consist of demineralized water.
9.1.3. One laboratory duplicate shall be run with each batch of samples. The
laboratory duplicate is prepared by removing an aliquant from the original
sample container.
9.1.4. A matrix spike sample is not required as a chemical yield tracer is used in
each sample.
9.2. The source preparation method should produce a sample test source in which the full
width-at-half-maximum (FWHM) for the tracer peak is less than 100 keV.1
9.2.1. Review each spectrum for evidence of peaks that overlap or evidence of
non-analyte activity that interferes with tracer or analyte peaks.
9.2.2. The sample test source may require reprocessing to remove interfering mass
if the FWHM limit cannot be achieved and peak overlap or non-analyte
peaks impact the quantification of 244Cm.
10. Calibration and Standardization
10.1. Set up the alpha spectrometry system according to the manufacturer's
recommendations consistent with ASTM Standard Practice D7282, Section 9.3,
"Alpha Spectrometry Initial Instrument Set-up" (Reference 16.3). The energy range
of the spectrometry system should, at minimum, include the range that encompasses
4.5 and 7.0 MeV.
10.2. Establish initial instrument quality controls as described in ASTM Standard Practice
D7282, Sections 10-15, "Initial Instrument Quality Control Testing" (Reference 16.3)
10.3. Calibrate each detector used to count samples according to ASTM Standard Practice
D7282, Section 18, "Alpha Spectrometry Instrument Calibrations" (Reference 16.3).
10.4. Perform Continuing Instrument Quality Control Testing according to ASTM Standard
Practice D7282, Sections 20, 21, and 24, "Continuing Instrument Quality Control
Testing" and "Quality Control for Alpha Spectrometry Systems" (Reference 16.3).
11. Procedure
11.1. Rapid Curium Separation using TEVA® and DGA Resins
Note: This method addresses the analysis of soluble curium only. Solid material, if present, must be
removed from the sample prior to aliquanting by filtering the unpreserved sample aliquant through a
0.45-jim filter. The solid material may be screened for radioactivity or saved for potential future analysis.
11.1.1. Aliquanting and Preparation
11.1.1.1. Aliquant 200 mL of sample into a 225-mL centrifuge tube.
1 This helps minimize interference from alpha-emitting isotopes with potentially overlapping energies.
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Rapid Radiochemical Method for Curium-244 in Water Samples
Aliquant a second 200 mL portion of one sample into a 225-mL
centrifuge tube as a sample duplicate.
Add 200 mL reagent water to an empty 225-mL centrifuge tube
as a reagent blank
Add 200 mL reagent water to an empty 225-mL centrifuge tube
for the LCS.
Acidify each sample with concentrated HNO3 to a pH of less
than 2.0 by adding HNO3. This usually requires about 0.5 mL of
HNO3.
Add 10-40 dpm 244Cm standard solution to the LCS centrifuge
tube, following laboratory protocol.
243
Add 10-40 dpm Am tracer to the blank, LCS, and sample and
sample duplicates, following laboratory protocol.
Add 1 mL of 1.5 M Ca(N03)2, 3 mL of 3.2 M (NH4)2HP04
solution and 2-3 drops of phenolphthalein indicator to each
centrifuge tube.
Slowly add concentrated NH4OH to each centrifuge tube with a
squeeze bottle. Add enough NH4OH to reach a dark pink
phenolphthalein end point and form Ca3(PC>4)2 precipitate. Cap
and mix tubes and centrifuge at 2000 revolutions per minute
(rpm) or more for ~5 minutes.
Note: If a sample aliquant larger than 200 mL is needed, the aliquant may be added to
a large beaker, heated on a hot plate to near boiling with reagents added, and allowed
to cool and settle. After pouring off enough of the supernate, the precipitate may be
transferred to a 225 mL tube, rinsing the beaker well with water, and centrifuged.
11.1.1.10. Decant supernatant solution and discard to waste.
11.1.2. Preparation of the Load Solution
11.1.2.1. Dissolve the calcium phosphate precipitate with 15 mL of 3 M
HNO3 - 1.0 M A1(N03)3. If the residue volume is large, or if
residual solids remain, an additional 5 mL may be needed to
obtain complete dissolution.
11.1.2.2. Add 0.5 mL of 1.5 M sulfamic acid to each sample. Swirl to mix.
Note: If elevated levels of 237Np are potentially present in the sample, also add 0.5 mL
of 4 mg/mL iron carrier to enhance neptunium (Np) reduction to Np4+. The addition of
ascorbic acid in the next step will convert Fe3+ to Fe2+ and ensure removal of Np on
TEVA® Resin.
11.1.2.3. Add 1.25 mL of 1.5 M ascorbic acid to each sample. Swirl to
mix. Wait 3 minutes.
Note: Plutonium (Pu), if present, will be adjusted to Pu4+ to ensure retention and
removal on TEVA® Resin. A small amount of brown fumes results from nitrite
reaction with sulfamic acid. The solution should clear with swirling. If the solution
does not clear (is still dark) an additional small volume of sodium nitrite may be
added to clear the solution.
11.1.1.2.
11.1.1.3.
11.1.1.4.
11.1.1.5.
11.1.1.6.
11.1.1.7.
11.1.1.8.
11.1.1.9.
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11.1.2.4. Add 1 mL of 3.5 M NaNC>2 to each sample. Swirl to mix.
Note: The load solution nitrate concentration is increased after valence adjustment to
provide greater retention of Am and more effective elution of calcium ions on DGA
Resin.
11.1.2.5. Add 1.5 mL concentrated HNO3 to each sample and swirl to mix.
Note: The steps in this section were optimized for a commercially available filtration
system. Other vacuum systems may be substituted here. The cartridges may be set up
and conditioned with nitric acid so that they are ready for column loading just prior
to completion of the valence adjustment steps. More than one vacuum box may be
used to increase throughput.
11.1.3. Set up TEVA® and DGA cartridges on the vacuum box system.
11.1.3.1. Place the inner centrifuge tube rack (supplied with vacuum box)
into the vacuum box with the centrifuge tubes in the rack. Place
the lid on the vacuum box system.
11.1.3.2. Place the yellow outer tips into all 24 openings of the lid of the
vacuum box. Fit an inner white tip into each yellow tip.
11.1.3.3. For each sample, assemble a TEVA® and a DGA cartridge and
lock these onto the inner white tip (DGA cartridge below
TEVA®).
11.1.3.4. Place reservoirs on the top end of the TEVA® cartridge.
11.1.3.5. Seal unused openings on the vacuum box by inserting yellow
caps included with the vacuum box into unused white tips to
achieve a good seal during the separation. Alternately, plastic
tape can be used to seal the unused lid holes.
11.1.3.6. Turn the vacuum on and ensure proper fitting of the lid.
11.1.3.7. Add 5 mL of 3 M HNO3 to the column reservoir to precondition
the TEVA® cartridges.
11.1.3.8. Adjust the vacuum to achieve a flow-rate of ~1 mL/min.
IMPORTANT: Unless the method specifies otherwise, use a flow rate of ~ 1 mL/min
for load and strip solutions and ~ 2 -3 mL/min for rinse solutions.
11.1.4. TEVA® and DGA Resin Separation
11.1.4.1. Transfer each solution from Step 11.1.2.5 into the appropriate
reservoir. Allow solution to pass through the stacked TEVA® +
DGA cartridge at a flow rate of ~1 mL/min.
11.1.4.2. Add 5 mL of 6 M HNO3 to each tube/beaker as a rinse and
transfer each solution into the appropriate reservoir (the flow rate
can be adjusted to ~2 mL/min).
11.1.4.3. Add a 5 mL rinse of 6 M HNO3 to each column (the flow rate
can be adjusted to ~2 mL/min).
11.1.4.4. Turn off vacuum, discard rinse solutions and remove reservoirs
and TEVA® cartridges and discard. Place new reservoirs on the
DGA cartridges.
11.1.4.5. Add a 20 mL rinse of 0.1 M HNO3 to each reservoir (flow rate
-1-2 mL/min).
Note: The rinses with dilute nitric acid remove uranium while curium
and americium are retained. Precipitation of uranium during
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microprecipitation is inhibited by adding hydrogen peroxide to ensure
uranium is present as U022+.
11.1.4.6. Add 15 mL of 3 M HNO3-O.25 M HF to each reservoir at -1-2
mL/min to complex and remove Th from the DGA Resin.
11.1.4.7. Add 3 mL of 4 M HC1 to each reservoir at ~l-2 mL/min to rinse
column of residual fluoride. Once the HC1 has passed through the
column, quickly pulse the vacuum two or three times to
minimize the amount of residual HC1 in the column prior to
proceeding.
11.1.4.8. Ensure that clean, labeled plastic tubes are placed in the tube
rack under each cartridge. For maximum removal of
interferences during elution, also change connector tips prior to
Cm/Am elution.
11.1.4.9. Add 10 mL of 0.25 M HC1 solution to elute curium and
americium from each cartridge, reducing the flow rate to ~1
mL/min (or slightly slower).
11.1.4.10. Set the curium fraction in the plastic tube aside for cerium
fluoride coprecipitation, Step 11.2.
11.1.4.11. Discard the DGA cartridge.
11.2. Preparation of the Sample Test Source
Note: Instructions below describe preparation of a single sample test source (STS). Several
STSs can be prepared simultaneously if a multi-channel vacuum manifold system is available.
11.2.1. Pipet 100 |iL of the cerium carrier solution into each tube.
11.2.2. Pipet 0.5 mL 30 wt. % H2O2 into each tube to prevent residual uranium from
precipitating.
11.2.3. Pipet 1 mL of concentrated HF into each tube.
11.2.4. Cap the tube and mix. Allow samples sit for ~ 15 minutes before filtering.
11.2.5. Set up a filter apparatus to accommodate a 0.1-micron, 25-mm membrane
filter on a microprecipitation filtering apparatus.
Caution: Following deposition of the microprecipitate, there is no visible difference
between the two sides of the filter.
11.2.6. If a hydrophobic filter is used, add a few drops of 95% ethanol to wet each
filter and apply vacuum. Ensure that there are no leaks along the sides
before proceeding.
11.2.7. While vacuum is applied, add 2-3 mL of filtered Type I water to each filter
and allow the liquid to drain.
11.2.8. Add the sample to the reservoir, rinsing the sample tubes with ~3 mL of
water and transfer this rinse to filter apparatus. Allow to drain.
11.2.9. Wash each filter with -2-3 mL of water and allow to drain.
11.2.10. Wash each filter with -1-2 mL of 95% ethanol to displace water.
11.2.11. Allow to drain completely before turning the vacuum off.
11.2.12. Mount the filter on a labeled adhesive mounting disk (or equivalent)
ensuring that the filter is not wrinkled and is centered on the mounting disk.
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Rapid Radiochemical Method for Curium-244 in Water Samples
11.2.13. Place the filter under a heat lamp for approximately 5 minutes or longer
until it is completely dry.
11.2.14. Count filters for an appropriate period of time by alpha spectrometry.
11.2.15. Discard the filtrate to waste for future disposal. If the filtrate is to be
retained, it should be stored in a plastic container since glass will be
attacked by HF.
Note: Other methods for STS preparation, such as electrodeposition or
microprecipitation with neodymium fluoride, may be used in lieu of the cerium
fluoride microprecipitation, but any such substitution must be validated as described
in Step 1.5.
12. Data Analysis and Calculations
12.1. Equations for activity concentration, combined standard uncertainty, and
radiochemical yield (if required):
12.1.1. The activity concentration of the analyte and its combined standard
uncertainty are calculated using the following equations:
AC _AtxRaxDtxIt
a Fax^xZ)ax/a
42xA2x/t2 , ,n2Ju\A) , u2(VJ , u\Rt)
uB(AC.)= u*(R.)xrr2\2 t'r2+AC,
xzr x/a \ 4* v; r;
+—v^+-
)2
J
o
A=e
D=q ^
Where
ACa = activity concentration of the analyte at time of collection (or other
specified reference time), in picocuries per liter (pCi/L)
At = activity of the tracer added to the sample aliquant on the tracer
solution reference date/time (pCi)
Ra = net count rate of the analyte in the defined region of interest (ROI),
in counts per second (see 12.1.2)
Rt = net count rate of the tracer in the defined ROI, in counts per second
(see 12.1.2)
Fa = volume of the sample aliquant (L)
Dt = correction factor for decay of the tracer from its reference date and
time to the midpoint of the counting period
Da = correction factor for decay of the analyte from the time of sample
collection (or other reference time) to the midpoint of the counting
period
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It = probability of a emission in the defined ROI per decay of the tracer
(Table 17.1)
/a = probability of a emission in the defined ROI per decay of the analyte
(Table 17.1)
uc(ACa) = combined standard uncertainty of the activity concentration of the
analyte (pCi/L)
u(At) = standard uncertainty of the activity of the tracer added to the sample
(pCi)
u(Ra) = standard uncertainty of the net count rate of the analyte (s ') (see
12.1.2)
u(Rt) = standard uncertainty of the net count rate of the tracer (s ') (see
12.1.2)
w(Va) = standard uncertainty of the size of the sample aliquant volume (L)
Xt = decay constant for the tracer radionuclide (s see Table 17.1),
Xa = decay constant for the analyte radionuclide (s see Table 17.1),
tt = time elapsed between the activity reference date for the tracer and
the midpoint of the sample count (s).
ta = time elapsed between the activity reference date for the sample (e.g.,
collection date) and the midpoint of the sample count (s).
Note: The uncertainties of the decay-correction factors and of the probability of decay
factors are assumed to be negligible.
Note: The equation for the combined standard uncertainty (//c(ACa)) calculation is arranged to
eliminate the possibility of dividing by zero if Ra = 0.
Note: The standard uncertainty of the activity of the tracer added to the sample must reflect the
uncertainty associated with the activity of the standard reference material and any other
significant sources of uncertainty such as those introduced during the preparation of the tracer
solution (e.g., weighing or dilution factors) and during the process of adding the tracer to the
sample.
12.1.2. The net count rate of an analyte or tracer and its standard uncertainty are
calculated using the following equations:
C C
R^ - x bx
K
and
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Rapid Radiochemical Method for Curium-244 in Water Samples
4 = sample count time (s)
Cbx = background counts in the same ROI as for x
tb = background count time (s)
u(Rx) = standard uncertainty of the net count rate of tracer or analyte, in
counts per second2
If the radiochemical yield of the tracer is requested, the yield and its combined
standard uncertainty can be calculated using the following equations:
0.037 xAtxDtxItxs
and
= RY x
\ 4 s
where:
RY
radiochemical yield of the tracer, expressed as a fraction
Rx
net count rate of the tracer, in counts per second
At
activity of the tracer added to the sample (pCi)
A
correction factor for decay of the tracer from its reference date and
time to the midpoint of the counting period
It
probability of a emission in the defined ROI per decay of the tracer
(Table 17.1)
£ =
detector efficiency, expressed as a fraction
II
s
o
5S
combined standard uncertainty of the radiochemical yield
u(Rt)
standard uncertainty of the net count rate of the tracer, in counts per
second
u(At)
standard uncertainty of the activity of the tracer added to the sample
(pCi)
u(s) =
standard uncertainty of the detector efficiency
12.1.3. If the critical level concentration (Lc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
"3
calculated using the following equations:
2 For methods with very low counts, MARLAP Section 19.5.2.2 recommends adding one count each to the gross
counts and the background counts when estimating the uncertainty of the respective net counts. This minimizes
negative bias in the estimate of uncertainty and protects against calculating zero uncertainty when a total of zero
counts are observed for the sample and background.
3 The formulations for the critical level and minimum detectable concentration are based on the Stapleton
Approximation as recommended in MARLAP Section 20A.2.2, Equations 20.54 and 20A.3.2, and Equation 20.74,
respectively (EPA 2004). The formulations presented here assume an error rate of a = 0.05, /; = 0.05 (with z, „ =
z, {; = 1.645) and d = 0.4. For methods with very low numbers of counts, these expressions provide better estimates
than do the traditional formulas for the critical level and MDC.
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Rapid Radiochemical Method for Curium-244 in Water Samples
=
0.4x
A
-1
+ 0.677 x
A
1 + -
+1.645 x
V lb )
{RbJb +0.4)x —x
x 4 x A x 11
t xV xR,xD x I
s a t a a
MDC=
2.71:
V J
+ 3.29
ba s
At x Dt x It
/.xF.x^xfl.x/,
where:
i?ba = background count rate for the analyte in the defined ROI, in counts
per second
12.2. Results Reporting
12.2.1. The following data should be reported for each result: volume of sample
used; yield of tracer and its uncertainty; and FWHM of each peak used in
the analysis.
12.2.2. The following conventions should be used for each result:
12.2.2.1. Result in scientific notation ± combined standard uncertainty.
13. Method Performance
13.1. Method validation results performed prior to analyzing samples are to be documented
and reported as required.
13.2. Expected processing time per batch of 10-20 samples plus QC:
13.2.1. For an analysis of a 0.2 L sample aliquant, precipitation and preparation of
load solution takes ~1 h.
13.2.2. Purification and separation using cartridges and vacuum box system should
take ~2 h.
13.2.3. The sample test source preparation step takes -0.75 h.
13.2.4. A four-hour counting time should be sufficient to meet the MQOs listed in
Step 1.4, assuming detector efficiency of 0.15-0.3, and radiochemical yield
of at least 0.5. A different counting time may be necessary to meet these
MQOs if any of the relevant parameters are significantly different.
13.2.5. Data should be ready for reduction -8-9 h after beginning of analysis.
14. Pollution Prevention: The method utilizes small volume (2 mL) extraction chromatographic
resin columns. This approach leads to a significant reduction in the volumes of load, rinse
and strip solutions, as compared to classical methods using ion exchange resins to separate
and purify the curium fraction.
15. Waste Management
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15.1. Types of waste generated per sample analyzed
15.1.1. Approximately 210 mL basic waste from the initial sample
preconcentration.
15.1.2. Approximately 65 mL of acidic waste from loading and rinsing the two
extraction columns will be generated.
15.1.3. Approximately 25 mL of acidic waste from the microprecipitation method
for source preparation will be generated. The waste contains 1 mL of HF
and ~ 5 mL of ethanol.
15.1.4. TEVA® cartridge - ready for appropriate disposal.
15.1.5. DGA cartridge - ready for appropriate disposal.
243
15.1.6. These waste streams may contain low levels of Am (added as tracer),
244Cm (added to LCS) and other radionuclides as present in samples.
15.2. Evaluate all waste streams according to disposal requirements by applicable
regulations.
16. References
Cited References
16.1. EPA 2009. Method Validation Guide for Radiological Laboratories Participating in
Incident Response Activities. Revision 0. Office of Air and Radiation, Washington,
DC. EPA 402-R-09-006, (June 2009). Available here.
16.2. EPA 2004. Multi-Agency Radiological Laboratory Analytical Protocols Manual
(MARLAP). 2004. EPA 402-B-1304 04-001A, July. Volume I, Chapters 6, 7, 20,
Glossary; Volume II and Volume III, Appendix G. Available here
16.3. ASTM D7282 "Standard Practice for Set-up, Calibration, and Quality Control of
Instruments Used for Radioactivity Measurements," ASTM Book of Standards 11.02,
current version, ASTM International, West Conshohocken, PA.
16.4. ASTM D1193, "Standard Specification for Reagent Water," ASTM Book of Standards
11.02, current version, ASTM International, West Conshohocken, PA.
Other References
16.5. EPA 2012. Rapid Radiochemical Methodfor Americium-241 in Building Materials
for Environmental Remediation Following Radiological Incidents. Office of Air and
Radiation, Washington, DC. Available here.
16.6. Maxwell, S., Culligan, B. and Noyes, G. 2010. Rapid Separation Method for Actinides
in Emergency Soil Samples, Radiochimica Acta. 98(12): 793-800.
16.7. Maxwell, S., Culligan, B., Kelsey-Wall, A. and Shaw, P. 2011. "Rapid Radiochemical
Method for Determination of Actinides in Emergency Concrete and Brick Samples,"
Analytica Chimica Acta. 701(1): 112-8.
16.8. VBS01, Rev. 1.4, "Setup and Operation Instructions for Eichrom's Vacuum Box
System (VBS)," Eichrom Technologies, LLC., Lisle, Illinois (January 2014).
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17. Tables, Diagrams, Flow Charts, and Validation Data
17.1. Tables
Table 17.1 Alpha Particle Energies and Abundances of Importance^11
Nuclide
Half-Life
(Years)
I
(s_1)
Abundance
a Emission Energy
in kilo electron volts
244Cm
18.11
1.213xlO-09
0.7690
5805
0.2310
5763
0.0150
6066
0.047
6058
0.010968
6010
243Cm
29.1
7.55 xlO-10
0.0568
5992
0.0069797
5876
0.730
5785
0.115
5742
0.015954
5686
0.0019942
5682
0.0013959
5639
2«/2«cm (combined)
18.11
1.213X10"09
1.000
5805
^Cm
0.4462
4.923 xlOHI8
0.2592
6113
0.7408
6069
0.0058
5529
0.0083
5489
245Cm
8.50xl03
2.58xl0-12
0.0045
5370
0.9320
5361
0.5000
5304
0.0032
5234
246Cm
4.76xl03
4.61xl0-12
0.822
5387
0.178
5344
0.138
5267
0.057
5212
247Cm
1.560xl07
1.408xl0"15
0.0120
5147
0.0200
4985
0.0160
4943
0.710
4870
0.047
4820
0.0016
5349
0.0016
5321
243Am
7.370xl03
2.980xl0-12
0.871
5275
0.112
5233
0.0136
5181
243Am (combined)
7.370xl03
2.980xl0-12
0.9998
5275
0.0037
5545
0.00225
5512
241 Am
432.6
5.078xl0-11
0.848
5486
0.131
5443
0.01660
5388
[1] Particle energies with abundances less than 0.1% have been omitted unless they are contiguous with the
radionuclide region of interest.
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Data were queried from the NUD AT 2 Decay Radiation database at the Brookhaven National Laboratory National
Nuclear Data Center, (http://www.nndc.bnl.gov/nudat2/indx dec.isp) on 9/19/2014.
Table 17.2 Alpha Emissions Sorted by Decreasing Energy
Half-Life
X
a Emission
Nuclide
(years)
(s"1)
Energy (keV)[11
Abundance
242Cm
0.4462
4.923 x 10""8
6113
0.7408
242Cm
0.4462
4.923 x 10""8
6069
0.2592
243Cm
29.1
7.55 x 10"1"
6066
0.0150
243Cm
29.1
7.55 x 10"1"
6058
0.047
243Cm
29.1
7.55 x 10"1"
6010
0.010968
243Cm
29.1
7.55 x 10"1"
5992
0.0568
243Cm
29.1
7.55 x 10"1"
5876
0.0069797
wCm
18.11
1.213x 10""9
5805
0.7690
243Cm
29.1
7.55 x 10"1"
5785
0.730
wCm
18.11
1.213x 10""9
5763
0.2310
243Cm
29.1
7.55 x 10"1"
5742
0.115
243Cm
29.1
7.55 x 10"1"
5686
0.015954
243Cm
29.1
7.55 x 10"1"
5682
0.0019942
243Cm
29.1
7.55 x 10"1"
5639
0.0013959
241 Am
4.326* 102
5.078xl0_n
5545
0.0037
245Cm
8.50xl03
2.58x 10"12
5529
0.0058
241 Am
4.326xl02
5.078xl0_n
5512
0.00225
245Cm
8.50xl03
2.58x 10"12
5489
0.0083
241 Am
4.326* 102
5.078x10-"
5486
0.848
241 Am
4.326xl02
5.078x10""
5443
0.131
241 Am
4.326x 102
5.078x10-"
5388
0.01660
246Cm
4.76xl03
4.61xl0"12
5387
0.822
245Cm
8.50xl03
2.58x 10"12
5370
0.0045
245Cm
8.50xl03
2.58x 10"12
5361
0.9320
243Am
7.370x 103
2.980x 10"12
5349
0.0016
246Cm
4.76xl03
4.61xl0"12
5344
0.178
243Am
7.370x 103
2.980x 10"12
5321
0.0016
245Cm
8.50xl03
2.58x 10"12
5304
0.5000
243Am
7.370x 103
2.980x 10"12
5275
0.871
247Cm
1.560xl07
1.408x 10"15
5267
0.138
245Cm
8.50xl03
2.58x 10"12
5234
0.0032
243Am
7.370x 103
2.980x 10"12
5233
0.112
247Cm
1.560xl07
1.408x 10"15
5212
0.057
247Cm
1.560xl07
1.408x 10"15
5147
0.0120
247Cm
1.560xl07
1.408x 10"15
4985
0.0200
247Cm
1.560xl07
1.408x 10"15
4943
0.0160
247Cm
1.560xl07
1.408x 10"15
4870
0.710
247Cm
1.560xl07
1.408x 10"15
4820
0.047
[1]Particle energies with abundances less than 0.1% have been omitted unless they would be contiguous with the
radionuclide region of interest.
Data were queried from the NUD AT 2 Decay Radiation database at Brookhaven National Laboratory National
Nuclear Data Center, (http://www.nndc.bnl.gov/nudat2/indx dec.isp) on 9/19/2014.
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Ingrowth Curves and Ingrowth Factors
This section intentionally left blank
17.2. Spectrum from a Processed Sample
140
105
70
Counts
35
3052.00
4296.00
5539.00
6783.00
8026.00
Energy (keV)
17.3. Decay Scheme
Curium-244 Spectrum
244
Cm
240
Pu
a V
<—
= 6.561x10 y
243
Cm
239
Pu
a V
<—
tv= 2.411x10 y
239
Pu
243
Am
V
P
=61.9m
239
Np
a V
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17.4. Flowchart
Separation Scheme and Timeline for the
Determination of 244Cm in Water Samples
Continue with Step 11.1.4.5
Discard TEVA® cartridge, and load
and rinse solutions (11.1.4.4)
Place fresh reservoirs above each
cartridge (11.1.4.4)
Vacuum box setup
• Assemble TEVA® +
DGA cartridges on
vacuum box (11.1.3.1 -
Condition cartridges with
3M HNO3 and adjust
flowto ~1 mL/min
Load sample onto TEVA® & DGA cartridges
Load sample @1 mL/min (11.1.4.1)
Add 5 mL6M HNO3 tuberinse to column @ ~2 mL/min (11.1.4.2)
Rinse column with 5 mL 6 MHN03 @ ~2 mL/min (11.1.4.3)
Calcium phosphate preconcentration
• Add 1 mL 1.5M Ca(N03)2, 3 mL 3.2M (NH4)2HP04,
and 2-3 drops phenolphthalein indicator (11.1.1.8)
• Add 15M NH4OH to pink phenolphthalein endpoint to
precipitate Ca3(P04)2 and centrifuge (11.1.1.9)
• Decant supernate to waste (11.1.1.10)
Aliquant preparation batch
• Aliquant 200 mL of each sample and QC sample into
centrifuge tubes (11.1.1.1 -11.1.1.4)
• Acidify with HN03to pH < 2 (11.1.1.5)
• Add 244Cm to LCS and 243Am tracer to all samples
Prepare load solution I adjust Pu to Pu4+
• Dissolve Ca3(P04)2 with 15 mL HN03/AI(N03)3 (11.1.2.1)
• Add 0.5 mL 1.5M sulfamic acid and swirl to mix (11.1.2.2)
• Add 1.25 mL 1.5M ascorbic acid and swirl to mix, and
wait 3 minutes (11.1.2.3)
• Add 1 mL3.5M sodium nitrite and swirl to mix (11.1.2.4)
• Add 1.5 mL concentrated nitric acid and swirl to mix
(11.1.2.5)
Elapsed Time
3A hour
1 hour
,2 hours
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Separation Scheme and Timeline for the
Determination of 244Cm in Water Samples (cont.)
Elapsed Time
2 hours
33A hours
8 hours
Continue from Step 11.1.4.4
Discard filtrates and
rinses(11.2.15)
Count sample test sources (STS)
by alpha spectrometry for244Cm and 243Am for
four hours oras needed to meet MQOs
(11.2.14)
Cm separation on DGA Resin
Rinse column with 20 mL 0.1 M HN03 @~1-2 mL/min (11.1.4.5)
• Rinse column with 15 mL 3M HNO3-0.25M HF @~1-2 mL/min (11.1.4.6)
Rinse column with 3 mL 4M HCI @~1-2 mL/min; remove excess HCI from
column (11.1.4.7)
Place fresh connectortips under each column and tubes under each column to
catch Cm (11.1.4.8)
• EluteCm with 10 mL 0.25M HCI @~1 mL/min (11.1.4.9)
Remove tubes for microprecipitation and continue with Step 11.2 (11.1.4.10)
Microprecipitation and sample test source preparation
Add 100 |jL (50 |jg) Ce carrier to each sample (11.2.1)
• Add 0.5 mL 30 wt% H202 (11.2.2)
Add 1 mL concentrated HF into each sample (11.2.3)
Cap tube, mix and wait 15 min (11.2.4)
Set up filtering apparatus (11.2.5 -11.2.7)
Filtersample onto 25-mm 0.1-|jm membrane filter(11.2.8)
Rinse with ~2-3 mL water and allow to drain (11.2.9)
Rinse with ~1-2 mL alcoholto displace water (11.2.10-11.2.11)
Mountfilterforcounting (11.2.12)
Place filter under heat lamp undergentle heat for~5 min (11.2.13)
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Appendix A:
Composition of Test Samples Used for Validation
Metals by ICP-MS
Concentration (jig/L)&
Be
0.015 (J)
Na
3,400
Mg
1,500
A1
15 (J)
K
1,500
Ca
17,000
V
0.30 (J)
Cr
0.075 (J)
Mn
6.3
Fe
26 (J)
Co
0.047 (J)
Ni
0.69 (J)
Cu
59
Zn
8.0
As
0.27 (J)
Se
0.11 (J)
Mo
<0.41 (U)
Ag
<0.0082 (U)
Cd
0.010 (J)
Sb
0.060 (J)
Ba
20
T1
0.054 (J)
Pb
0.23 (J)
U
0.010 (J)
Radionuclide
Activity Concentration (pCi/L)
244Cm
0.012 ± 0.050 #
252/250q?
0.001 ± 0.044 #
241 Am
0.20 ± 0.29 #
232Th
0.003 ± 0.034 &
:'Th
0.052 ±0.081 &
228Th
0.31 ± 0.12 &
238u
0.18 ± 0.12 &
235u
0.219 ±0.095 &
234u
0.232 ± 0.096 &
226Ra
0.049 ± 0.024 &
Qualifiers:
(U) - Result is less than the Instrument Detection Limit (IDL) per
SW846 Method 6020A
(J) - Result falls between the IDL and the reporting limit
&Mean ± 2 standard deviations of triplicate analyses of each of two Montgomery,
Alabama, tap water
# Mean ± 2 standard deviations of replicate analysis of seven samples of
Montgomery, Alabama, tap water
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