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United States
Environmental Protection
Agency
Office of Radiation and Indoor Air
National Air and Radiation
Environmental Laboratory
EPA 402-R-10-001
February 2010
www.epa.gov/narel
Rapid Radiochemical Methods for Selected
Radionuclides in Water for Environmental
Restoration Following Homeland
Security Events
228Ra
**° 30V*
B&^l
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EPA 402-R-10-001
www.epa.gov/narel
February 2010
Revision 0
Rapid Radiochemical Methods
for Selected Radionuclides in Water
for Environmental Restoration Following
Homeland Security Events
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 Radiochemical Methods for Selected Radionuclides in Water
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 contracts 68-W-03-038, work assignment
43, and EP-W-07-037, work assignments B-41 and 1-41, all managed by David Carman. Mention of trade
names or specific applications does not imply endorsement or acceptance by EPA.
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Rapid Radiochemical Methods for Selected Radionuclides in Water
Preface
This compendium provides rapid radioanalytical methods for selected radionuclides in an
aqueous matrix. These new methods were developed to expedite the analytical turnaround time
necessary to prioritize sample processing while providing quantitative results that meet measure-
ment quality objectives applicable to the intermediate and recovery phases of a nuclear or
radiological incident of national significance, such as the detonation of an improvised nuclear
device or a radiological dispersal device. It should be noted that these methods were not
developed for compliance monitoring of drinking water samples, and they should not be
considered as having EPA approval for that or any other regulatory program.
This is the first issue of rapid methods for amercium-241, plutonium-238 and plutonium-
239/240, isotopic uranium, radiostrontium (strontium-90), and radium-226. They have been
single-laboratory validated in accordance with the guidance in Method Validation Guide for
Qualifying Methods Used by Radiological Laboratories Participating in Incident Response
Activities., Validation and Peer Review of U.S. Environmental Protection Agency Radiochemical
Methods of Analysis, and Chapter 6 of Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP). Depending on the availability of resources, EPA plans to
perform multi-laboratory validations on these methods.
These methods are capable of achieving a required relative method uncertainty of 13% at or
above a default analytical action level based on conservative risk or dose values for the
intermediate and recovery phases. The methods also have been tested to determine the time
within which a batch of samples can be analyzed. For these radionuclides, results for a batch of
samples can be provided within a turnaround time of about 8 to 38 hours instead of the days to
weeks required by some previous methods.
The need to ensure adequate laboratory infrastructure to support response and recovery actions
following a major radiological incident has been recognized by a number of federal agencies.
The Integrated Consortium of Laboratory Networks (ICLN), created in 2005 by 10 federal
agencies,1 consists of existing laboratory networks across the federal government. The ICLN is
designed to provide a national infrastructure with a coordinated and operational system of
laboratory networks that provide timely, high-quality, and interpretable results for early detection
and effective consequence management of acts of terrorism and other events requiring an
integrated laboratory response. It also designates responsible federal agencies (RFAs) to provide
laboratory support across response phases for chemical, biological, and radiological agents. To
meet its RFA responsibilities for environmental samples, EPA has established the Environmental
Response Laboratory Network (ERLN) to address chemical, biological, and radiological threats.
For radiological agents, EPA is the RFA for monitoring, surveillance, and remediation, and will
share responsibility for overall incident response with the U.S. Department of Energy (DOE). As
part of the ERLN, EPA's Office of Radiation and Indoor Air is leading an initiative to ensure
that sufficient environmental radioanalytical capability and competency exist across a core set of
laboratories to carry out EPA's designated RFA responsibilities.
1 Departments of Agriculture, Commerce, Defense, Energy, Health and Human Services, Homeland Security,
Interior, Justice, and State, and the U.S. Environmental Protection Agency.
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Rapid Radiochemical Methods for Selected Radionuclides in Water
EPA's responsibilities, as outlined in the National Response Framework, include response and
recovery actions to detect and identify radioactive substances and to coordinate federal
radiological monitoring and assessment activities. This document was developed to provide
guidance to those radioanalytical laboratories that will support EPA's response and recovery
actions following a radiological or nuclear incident of national significance.
As with any technical endeavor, actual radioanalytical projects may require particular methods or
techniques to meet specific measurement quality objectives. Sampling and analysis following a
radiological or nuclear incident will present new challenges in terms of types of matrices, sample
representativeness, and homogeneity not experienced with routine samples. A major factor in
establishing measurement quality objectives is to determine and limit the uncertainties associated
with each aspect of the analytical process.
These methods supplement guidance in a planned series designed to present radioanalytical
laboratory personnel, Incident Commanders (and their designees), and other field response
personnel with key laboratory operational considerations and likely radioanalytical requirements,
decision paths, and default data quality and measurement quality objectives for samples taken
after a radiological or nuclear incident, including incidents caused by a terrorist attack.
Documents currently completed or in preparation include:
• Radiological Laboratory Sample Analysis Guide for Incidents of National Significance -
Radionuclides in Water (EPA 402-R-07-007, January 2008)
• Radiological Laboratory Sample Analysis Guide for Incidents of National Significance -
Radionuclides in Air (EPA 402-R-09-007, June 2009)
• Radiological Laboratory Sample Screening Analysis Guide for Incidents of National
Significance (EPA 402-R-09-008, June 2009)
• Method Validation Guide for Qualifying Methods Used by Radiological Laboratories
Participating in Incident Response Activities (EPA 402-R-09-006, June 2009)
• Guide for Laboratories — Identification, Preparation, and Implementation of Core
Operations for Radiological or Nuclear Incident Response (EPA 402-R-10-002, June 2010)
• A Performance-Based Approach to the Use of Swipe Samples in Response to a Radiological
or Nuclear Incident (in preparation)
• Guide for Radiological Laboratories for the Control of Radioactive Contamination and
Radiation Exposure (in preparation)
• Radiological Laboratory Sample Analysis Guide for Radiological or Nuclear Incidents -
Radionuclides in Soil (in preparation)
Comments on this document, or suggestions for future editions, should be addressed to:
Dr. John Griggs
U.S. Environmental Protection Agency
Office of Radiation and Indoor Air
National Air and Radiation Environmental Laboratory
540 South Morris Avenue
Montgomery, AL 36115-2601
(334) 270-3450
Griggs.John@epa.gov
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Rapid Radiochemical Methods for Selected Radionuclides in Water
Acknowledgments
These methods were developed by the National Air and Radiation Environmental Laboratory
(NAREL) of EPA's Office of Radiation and Indoor Air (ORIA) in cooperation with and funding
from the National Homeland Security Research Center (NHSRC) of the Office of Research and
Development. Dr. John Griggs was the project lead for this document. Several individuals
provided valuable support and input to this document throughout its development. Special
acknowledgment and appreciation are extended to Kathy Hall, of NHSRC. We also wish to
acknowledge the valuable suggestions provided by Cynthia White and her colleagues at Sanford
Cohen & Associates' Southeastern Laboratory and Stephen Workman and his colleagues of
ALS-Paragon Laboratories, who conducted the method-validation studies. Dr. Keith McCroan,
of NAREL, provided significant assistance with the equations used to calculate minimum
detectable concentrations and critical levels. A special thank you is extended to Dan Mackney,
also of NAREL, for his review and comments. Numerous other individuals, both inside and
outside of EPA, provided comments and criticisms of these methods, and their suggestions
contributed greatly to the quality, consistency, and usefulness of the final methods. Technical
support was provided by Dr. N. Jay Bassin, Dr. Anna Berne, Mr. David Burns, Dr. Carl V.
Gogolak, Dr. Robert Litman, Dr. David McCurdy, Mr. Robert Shannon, and Ms. M. Leca
Buchan of Environmental Management Support, Inc.
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Rapid Radiochemical Methods for Selected Radionuclides in Water
CONTENTS
Acronyms, Abbreviations, Units, and Symbols v
Radiometric and General Unit Conversions vii
Americium-241 in Water: Rapid Method for High-Activity Samples 241 Am - Page 1
Plutonium-238 and Plutonium-239/240 in Water: Rapid Method for High-Activity
Samples 238'239/240Pu - Page 1
Radium-226 in Water: Rapid Method Technique for High-Activity Samples 2226Ra - Page 1
Total Radiostrontium (Sr-90) in Water: Rapid Method for High-Activity Samples ....90Sr - Page 1
Isotopic Uranium in Water: Rapid Method for High-Activity Samples U-nat - Page 1
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Rapid Radiochemical Methods for Selected Radionuclides in Water
Acronyms, Abbreviations, Units, and Symbols
a probability of a Type I decision error
AAL analytical action level
ACS American Chemical Society
ADL analytical decision level
APS analytical protocol specification
ft probability of a Type II decision error
Bq becquerel
Ci curie
cm centimeter (1CT2 meter)
cpm counts per minute
cps counts per second
CRM certified reference material (see also SRM)
CSU combined standard uncertainty
d day
dpm disintegrations per minute
DOE Department of Energy
dps disintegrations per second
DRP discrete radioactive particle
EPA U.S. Environmental Protection Agency
FWHM full width at half maximum
g gram
GPC gas-flow proportional counter
h hour
ICP-AES inductively coupled plasma - atomic emission spectrometry
ICLN Integrated Consortium of Laboratory Networks
ID [identifier] [identification number]
ID inside diameter
IND improvised nuclear device
keV kiloelectronvolts (103 electronvolts)
L liter
LCS laboratory control sample
m meter
M molar
MARLAP Multi-Agency Radiological Laboratory Analytical Protocols Manual
MDC minimum detectable concentration
MeV megaelectronvolts (106 electronvolts)
min minute
mg milligram (1CT3 gram)
mL milliliter (1CT3 liter)
mm millimeter (1CT3 meter)
MQO measurement quality obj ective
NAREL EPA's National Air and Radiation Environmental Laboratory, Montgomery, AL
NHSRC EPA's National Homeland Security Research Center, Cincinnati, OH
NIST National Institute of Standards and Technology
NRC U.S. Nuclear Regulatory Commission
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Rapid Radiochemical Methods for Selected Radionuclides in Water
ORIA U.S. EPA Office of Indoor Air and Radiation
^MR required relative method uncertainty
pCi picocurie (1CT9 curie)
PPE personal protective equipment
ppm parts per million
QA quality assurance
QAPP quality assurance proj ect plan
QC quality control
RDD radiological dispersal device
RFA responsible federal agencies
ROI region of interest
SDWA Safe Drinking Water Act
s second
STS sample test source
MMR required method uncertainty
ug microgram (!CT6gram)
um micrometer (1CT6 meter)
uL microliter (1CT6 liter)
WCS working calibration source
y year
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Rapid Radiochemical Methods for Selected Radionuclides in Water
Radiometric and General Unit Conversions
To Convert
years (y)
disintegrations per
second (dps)
Bq
Bq/kg
Bq/m3
Bq/m3
microcuries per
milliliter (^iCi/mL)
disintegrations per
minute (dpm)
cubic feet (ft3)
gallons (gal)
gray (Gy)
roentgen equivalent
man (rem)
To
seconds (s)
minutes (min)
hours (h)
days (d)
becquerels (Bq)
picocuries (pCi)
pCi/g
pCi/L
Bq/L
pCi/L
(iCi
pCi
cubic meters (m3)
liters (L)
rad
sievert (Sv)
Multiply by
3.16xl07
5.26xl05
8.77xl03
3.65xl02
1
27.0
2.70xl(T2
2.70xl(T2
io-3
109
4.50xlO~7
4.50XKT1
2.83xl(T2
3.78
IO2
io-2
To Convert
s
min
h
d
Bq
pCi
pCi/g
pCi/L
Bq/L
pCi/L
pCi
na
m3
L
rad
Sv
To
y
dps
Bq
Bq/kg
Bq/m3
Bq/m3
(iCi/mL
dpm
ft3
gal
Gy
rem
Multiply by
3.17xl(T8
1.90xl(T6
1.14xl(T4
2.74xl(T3
1
3.70xl(T2
37.0
37.0
IO3
io-9
2.22
2.22xl06
35.3
0.264
io-2
IO2
NOTE: Traditional units are used throughout this document instead of the International System of
Units (SI). Conversion to SI units will be aided by the unit conversions in this table.
02/23/2010
vn
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February 2010
Revision 0
Rapid Radiochemical Method for
Americium-241 in Water
for Environmental Restoration Following
Homeland Security Events
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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AMERiciUM-241 IN WATER:
RAPID METHOD FOR HIGH-ACTIVITY SAMPLES
1. Scope and Application
1.1. The method will be applicable to samples where radioactive contamination is either
from known or unknown origins. If any filtration of the sample is performed prior to
starting the analysis, those solids should be analyzed separately. The results from the
analysis of these solids should be reported separately (as a suspended activity
concentration for the water volume filtered), but identified with the filtrate results.
1.2. The method is specific for 241Am in drinking water and other aqueous samples.
However, if any isotopes of curium are present in the sample, they will be carried with
americium during the analytical separation process and will be observed in the final
alpha spectrum.
1.3. The method uses rapid radiochemical separation techniques for determining americium
in water samples following a radiological or nuclear incident. Although the method can
detect concentrations of 241Am on the same order of magnitude as methods used for the
Safe Drinking Water Act (SDWA), the method is not a substitute for SDWA-approved
methods for 241 Am.
1.4. The method is capable of achieving a required method uncertainty for 241 Am of 1.9
pCi/L at an analytical action level of 15 pCi/L. To attain the stated measurement quality
objectives (MQOs) (see Sections 9.3 and 9.4), a sample volume of approximately 200
mL and count time of at least 1 hour are recommended. The sample turnaround time
and throughput may vary based on additional project MQOs, the time for analysis of
the final counting form, and initial sample volume. 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 (EPA 2009, reference 16.5).
1.5. The method is intended to be used for water samples that are similar in composition to
drinking water. The rapid 241 Am method was 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 (EPA 2009,
reference 16.5) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP 2004, reference 16.6). The matrix used for the
determination of 241Am was drinking water from Atlanta, GA. See the appendix for a
listing of the chemical constituents of the water.
1.6. Multi-radionuclide analysis using sequential separation may be possible using this
method in conjunction with other rapid methods.
1.7. The method is applicable to the determination of soluble 241 Am. The method is not
applicable to the determination of 241Am in highly insoluble particulate matter possibly
present in water samples contaminated as a result of a radiological dispersion device
(ROD) event.
2. Summary of Method
2.1. The method is based on a sequence of two chromatographic extraction resins used to
concentrate, isolate, and purify americium by removing interfering radionuclides as
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Americium-241 in Water: Rapid Method for High-Activity Samples
well as other components of the water matrix in order to prepare the americium fraction
for counting by alpha spectrometry. The method utilizes vacuum-assisted flow to
improve the speed of the separations. Prior to the use of the extraction resins, the water
sample is filtered as necessary to remove any insoluble fractions, equilibrated with
243Am tracer, and concentrated by evaporation or calcium phosphate precipitation. The
sample test source (STS) is prepared by microprecipitation with NdF3. Standard
laboratory protocol for the use of an alpha spectrometer should be used when the
sample is ready for counting.
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 decisionmaker to choose one of the alternative
actions.
3.3. Analytical Decision Level (ADL). The analytical decision level refers to the value that
is less than the AAL and based on the acceptable error rate and the required method
uncertainty.
3.4. 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).
3.5. Multi-Agency Radiological Laboratory Analytical Protocols Manual (See Reference
16.6.).
3.6. 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.
3.7. Radiological Dispersal Device (ROD), i.e., a "dirty bomb." This is an unconventional
weapon constructed to distribute radioactive material(s) into the environment either by
incorporating them into a conventional bomb or by using sprays, canisters, or manual
dispersal.
3.8. Required Method Uncertainty (MMR). The required method uncertainty is a target value
for the individual measurement uncertainties, and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method uncertainty
is applicable below an AAL.
3.9. Required Relative Method Uncertainty (^R). The required relative method uncertainty
is the WMR divided by the AAL and typically expressed as a percentage. It is applicable
above the AAL.
3.10. 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: Alpha-emitting radionuclides with irresolvable alpha energies, such as
241 Am (5.48 MeV)), 238Pu (5.50 MeV), and 228Th (5.42 MeV), must be chemically
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Americium-241 in Water: Rapid Method for High-Activity Samples
separated to enable radionuclide-specific measurements. This method separates these
radionuclides effectively. The significance of peak overlap will be determined by the
individual detector's alpha energy resolution characteristics and the quality of the final
precipitate that is counted.
4.2. Non-Radiological: Very high levels of competing higher valence anions (greater than
divalent such as phosphates) will lead to lower yields when using the evaporation
option due to competition with active sites on the resin. If higher valence anions are
present, the phosphate precipitation option may need to be used initially in place of
evaporation. If calcium phosphate coprecipitation is performed to collect americium
(and other potentially present actinides) from large-volume samples, the amount of
phosphate added to coprecipitate the actinides (in Step 11.1.4.3) should be reduced to
accommodate the sample's high phosphate concentration.
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.
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. Hot Particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles" (DRPs), will
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 or finer filter
will minimize the presence of these particles.
5.2.1.2. 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 causing contamination.
5.2.1.3. Filter media should be individually surveyed for the presence of these
particles, and this information should be reported with the final sample
results.
5.2.2. For samples with detectable activity concentrations of this radionuclide, 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. Analytical balance with a 0.01-g readability or better.
6.2. Cartridge reservoirs, 10- or 20-mL syringe style with locking device, or equivalent.
6.3. Centrifuge able to accommodate 250-mL flasks.
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Americium-241 in Water: Rapid Method for High-Activity Samples
6.4. Centrifuge flasks, 250-mL capacity.
6.5. Filter with 0.45-um membrane.
6.6. Filter apparatus with 25-mm-diameter polysulfone filtration chimney, stem support, and
stainless steel support. A single-use (disposable) filter funnel/filter combination may be
used, to avoid cross-contamination.
6.7. 25-mm polypropylene filter, 0.1 -um pore size, or equivalent.
6.8. Stainless steel planchets or other sample mounts able to hold the 25 mm filter.
6.9. Tweezers.
6.10. 100-uL pipette or equivalent and appropriate plastic tips.
6.11. 10-mL plastic culture tubes with caps.
6.12. Tips, white inner, Eichrom part number AC-1000-IT, or equivalent.
6.13. Tips, yellow outer, Eichrom part number AC-1000-OT, or equivalent.
6.14. Vacuum box, such as Eichrom part number AC-24-BOX, or equivalent.
6.15. Vortex mixer.
6.16. Vacuum pump or laboratory vacuum system.
6.17. Miscellaneous laboratory ware, plastic or glass, 250 mL and 350 mL.
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 laboratory water should be understood to mean Type I
Reagent water. All solutions used in microprecipitation should be prepared with water filtered through a
0.45-um (or better) filter.
7.1. Am-243 tracer solution: 6-10 dpm of 243Am per aliquant, activity added known to at
least 5% (combined standard uncertainty < 5%).
7.2. Ammonium hydrogen phosphate (3.2 M): Dissolve 106 g of ammonium hydrogen
phosphate ((NH4)2FIPO4) in 200 mL of water, heat gently to dissolve, and dilute to 250
mL with water.
7.3. Ammonium hydroxide (15 M): Concentrated NH4OH, available commercially.
7.4. Ammonium thiocyanate indicator (1 M): Dissolve 7.6 g of ammonium thiocyanate
(NH4SCN) in 90 mL of water and dilute to 100 mL with water. An appropriate quantity
of sodium thiocyanate (8.1 g) or potassium thiocyanate (9.7 g) may be substituted for
ammonium thiocyanate.
7.5. Ascorbic acid (1 M): Dissolve 17.6 g of ascorbic acid (CeHgOe) in 90 mL of water and
dilute to 100 mL with water. Prepare weekly.
7.6. Calcium nitrate (0.9 M): Dissolve 53 g of calcium nitrate tetrahydrate (Ca(NO3)2'4H2O)
in 100 mL of water and dilute to 250 mL with water.
7.7. Ethanol, 100%: Anhydrous C2H5OH, available commercially.
7.7.1. Ethanol (-80% v/v): Mix 80 mL 100% ethanol and 20 mL water.
7.8. Ferrous sulfamate (0.6 M): Add 57 g of sulfamic acid (NH2SO3H) to 150 mL of water,
heat to 70°C. Slowly add 7 g of iron powder (< 100 mesh size) while heating and
stirring with a magnetic stirrer until dissolved (may take as long as two hours). Filter
the hot solution using a qualitative filter, transfer to flask, and dilute to 200 mL with
water. Prepare fresh weekly.
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Americium-241 in Water: Rapid Method for High-Activity Samples
7.9. Hydrochloric acid (12 M): Concentrated HC1, available commercially.
7.9.1. Hydrochloric acid (9 M): Add 750 mL of concentrated HC1 to 100 mL of water
and dilute to 1 L with water.
7.9.2. Hydrochloric acid (4 M): Add 333 mL of concentrated HC1 to 500 mL of water
and dilute to 1 L with water.
7.9.3. Hydrochloric acid (1 M): Add 83 mL of concentrated HC1 to 500 mL of water
and dilute to 1 L with water.
7.10. Hydrofluoric acid (28 M): Concentrated HF, available commercially.
7.10.1. Hydrofluoric acid (0.58 M): Add 20 mL of concentrated HF to 980 mL of
filtered demineralized water and mix. Store in a plastic bottle.
7.11. Neodymium standard solution (1000 ug/mL): May be purchased from a supplier of
standards for atomic spectroscopy.
7.12. Neodymium carrier solution (0.50 mg/mL): Dilute 10 mL of the neodymium standard
solution (7.11) to 20.0 mL with filtered demineralized water. This solution is stable.
7.13. Neodymium fluoride substrate solution (10 |ig/mL): Pipette 5 mL of neodymium
standard solution (7.11) into a 500-mL plastic bottle. Add 460 mL of 1-M HC1 to the
plastic bottle. Cap the bottle and shake to mix. Measure 40 mL of concentrated HF in a
plastic graduated cylinder and add to the bottle. Recap the bottle and shake to mix
thoroughly. This solution is stable for up to six months.
7.14. Nitric acid (16 M): Concentrated HNO3, available commercially.
7.14.1. Nitric acid (3 M): Add 191 mL of concentrated HNO3 to 700 mL of water and
dilute to 1 L with water.
7.14.2. Nitric acid (2 M): Add 127 mL of concentrated HNO3 to 800 mL of water and
dilute to 1 L with water.
7.14.3. Nitric acid (0.5 M): Add 32 mL of concentrated HNO3 to 900 mL of water and
dilute to 1 L with water.
7.15. Nitric acid (2M) - sodium nitrite (0.1 M) solution: Add 32 mL of concentrated HNO3
(7.14) to 200 mL of water and mix. Dissolve 1.7 g of sodium nitrite (NaNCh) in the
solution and dilute to 250 mL with water. Prepare fresh daily.
7.16. Nitric acid (3 M) - aluminum nitrate (l.OM) solution: Dissolve 213 g of anhydrous
aluminum nitrate (A1(NO3)3) in 700 mL of water. Add 190 mL of concentrated HNO3
(7.14) and dilute to 1 L with water. An appropriate quantity of aluminum nitrate
nonahydrate (375 g) may be substituted for anhydrous aluminum nitrate.
7.17. Phenolphthalein solution: Dissolve 1 g of phenolphthalein in 100 mL 95% isopropyl
alcohol and dilute with 100 mL of water.
7.18. TRU Resin: 2-mL cartridge, 50- to 100-|j,m mesh size, Eichrom part number TR-R50-S
and TR-R200-S, or equivalent.
7.19. UTEVA Resin: 2-mL cartridge, 50- to 100-|j,m mesh size, Eichrom part number UT-
R50-S and UT-R200-S, or equivalent.
Sample Collection, Preservation, and Storage
8.1. No sample preservation is required if sample is delivered to the laboratory within 3
days of sampling date/time.
8.2. If the dissolved concentration of americium is sought, the insoluble fraction must be
removed by filtration before preserving with acid.
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Americium-241 in Water: Rapid Method for High-Activity Samples
8.3. If the sample is to be held for more than 3 days, concentrated HNOs shall be added to
achieve a pH<2.
9. Quality Control
9.1. 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 manual and
procedures shall be used to determine acceptable performance for this method.
9.1.1. A laboratory control sample (LCS) shall be run with each batch of samples. The
concentration of the LCS shall 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 laboratory 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 may be included as a batch quality control sample if
there is concern that matrix interferences may compromise chemical yield
measurements or overall data quality.
9.2. The source preparation method should produce a sample test source whose spectrum
shows the full width at half maximum (FWHM) of-60-80 keV for each peak in the
spectrum. Precipitate reprocessing should be considered if this range of FWHM cannot
be achieved.
9.3. This method is capable of achieving a WMR of 1.9 pCi/L at or below an action level of 15
pCi/L. This may be adjusted in the event specific MQOs are different.
9.4. This method is capable of achieving a ^MR 13% above 15 pCi/L. This may be adjusted if
the event specific MQOs are different.
9.5. This method is capable of achieving a required minimum detectable concentration
(MDC)of 1.5pCi/L.
10. Calibration and Standardization
10.1. Set up the alpha spectrometry system according to the manufacturer's
recommendations. The energy range of the spectrometry system should at least
include the region between 3 and 8 MeV.
10.2. Calibrate each detector used to count samples according to ASTM Standard Practice
D7282, Section 18, "Alpha Spectrometry Instrument Calibrations" (see Reference
16.3).
10.3. Continuing Instrument Quality Control Testing shall be performed according to
ASTM Standard Practice D7282, Sections 20, 21, and 24.
11. Procedure
11.1. Water Sample Preparation
11.1.1. As required, filter the 100- to 200-mL sample aliquant through a 0.45-um
filter and collect the sample in an appropriate size beaker.
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Americium-241 in Water: Rapid Method for High-Activity Samples
11.1.2. Acidify the sample with concentrated HNOs to a pH of less than 2.0 by
adding enough HNOs. This usually requires about 2 mL of HNOs per 1000
mL of sample.
11.1.3. Add 6-10 dpm of 243Am as atracer, following laboratory protocol.
Note: For a sample approximately 100 mL or less, the evaporation option is
recommended. Proceed to Step 11.1.5. Otherwise, go to Step 11.1.4.
11.1.4. Calcium phosphate coprecipitation option
11.1.4.1. Add 0.5 mL of 0.9-M Ca(NO3)2 to each beaker. Place each
beaker on a hot plate, cover with a watch glass, and heat until
boiling.
11.1.4.2. Once the sample boils, take the watch glass off the beaker and
lower the heat.
11.1.4.3. Add 2-3 drops of phenolphthalein indicator and 200 |jL of 3.2 M
(NH4)2HPO4 solution.
11.1.4.4. Add enough concentrated NH4OH with a squeeze bottle to reach
the phenolphthalein end point and form Ca3(PO4)2 precipitate.
NH4OH should be added very slowly. Stir the solution with a
glass rod. Allow the sample to heat gently to digest the
precipitate for another 20-30 minutes.
11.1.4.5. If the sample volume is too large to centrifuge the entire sample,
allow precipitate to settle until solution can be decanted (30
minutes to 2 hours) and go to Step 11.1.4.7.
11.1.4.6. If the volume is small enough to centrifuge, go to Step 11.1.4.8.
11.1.4.7. Decant supernatant solution and discard to waste.
11.1.4.8. Transfer the precipitate to a 250-mL centrifuge tube, completing
the transfer with a few milliliters of water, and centrifuging the
precipitate for approximately 10 minutes at 2000 rpm.
11.1.4.9. Decant supernatant solution and discard to waste.
11.1.4.10. Wash the precipitate with an amount of water approximately
twice the volume of the precipitate. Mix well using a stirring rod,
breaking up the precipitate if necessary. Centrifuge for 5-10
minutes at 2000 rpm. Discard the supernatant solution.
11.1.4.11. Dissolve precipitate in approximately 5 mL concentrated HNOs
Transfer solution to a 100-mL beaker. Rinse centrifuge tube with
2-3 mL of concentrated HNO3 and transfer to the same beaker.
Evaporate solution to dryness and go to Step 11.2.
11.1.5. Evaporation option to reduce volume and to digest organic components
11.1.5.1. Evaporate sample to less than 50 mL and transfer to a 100-mL
beaker.
Note: For some water samples, CaSO4 formation may occur during
evaporation. If this occurs, use the Ca3(PO4)2 precipitation option in Step
11.1.4.
241
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11.1.5.2. Gently evaporate the sample to dryness and redissolve in
approximately 5 mL of concentrated HNOs.
11.1.5.3. Repeat Step 11.1.5.2 two more times, evaporate to dryness, and
go to Step 11.2.
11.2. Actinide Separations Using Eichrom Resins
11.2.1. Redissolve Ca3(PO4)2 residue or evaporated water sample
11.2.1.1. Dissolve either residue with 10 mL of 3-M HNO3 - 1.0-M
A1(N03)3.
Note: An additional 5 mL may be necessary if the residue volume is large.
11.2.1.2. Add 2 mL of 0.6-M ferrous sulfamate to each solution. Swirl to
mix.
Note: If the additional 5 mL was used to dissolve the sample in Step
11.2.1.1, add a total of 3 mL of ferrous sulfamate solution.
11.2.1.3. Add 1 drop of 1 -M ammonium thiocyanate indicator to each
sample and mix.
Note: The color of the solution turns deep red, due to the presence of
soluble ferric thiocyanate complex.
11.2.1.4. Add 1 mL of 1-M ascorbic acid to each solution, swirling to mix.
Wait for 2-3 minutes.
Note: The red color should disappear, which indicates reduction of Fe+3
to Fe+2. If the red color still persists, then additional ascorbic acid solution
has to be added drop-wise with mixing until the red color disappears.
Note: If particles are observed suspended in the solution, centrifuge the
sample. The supernatant solution will be transferred to the column in
Step 11.2.3.1. The precipitates will be discarded.
11.2.2. Setup of UTEVA and TRU cartridges in tandem on the vacuum box system
Note: Steps 11.2.2.1 to 11.2.2.5 deal with a commercially available filtration system.
Other vacuum systems developed by individual laboratories may be substituted here
as long as the laboratory has provided guidance to analysts in their use.
11.2.2.1. Place the inner tube rack (supplied with vacuum box) into the
vacuum box with the centrifuge tubes in the rack. Fit the lid to
the vacuum system box.
11.2.2.2. Place the yellow outer tips into all 24 openings of the lid of the
vacuum box. Fit in the inner white tip into each yellow tip.
11.2.2.3. For each sample solution, fit in a TRU cartridge on to the inner
white tip. Ensure the UTEVA cartridge is locked into the top end
of the TRU cartridge.
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Americium-241 in Water: Rapid Method for High-Activity Samples
11.2.2.4. Lock syringe barrels (funnels/reservoirs) to the top end of the
UTEVA cartridge.
11.2.2.5. Connect the vacuum pump to the box. Turn the vacuum pump on
and ensure proper fitting of the lid.
IMPORTANT: The unused openings on the vacuum box should be
sealed. Yellow caps (included with the vacuum box) can be used to plug
unused white tips to achieve good seal during the separation.
11.2.2.6. Add 5 mL of 3-M HNOs to the funnel to precondition the
UTEVA and TRU cartridges.
11.2.2.7. Adjust the vacuum pressure to achieve a flow-rate of ~1 mL/min.
IMPORTANT: Unless otherwise specified in the procedure, use a flow
rate of ~1 mL/min for load and strip solutions and ~3 mL/min for rinse
solutions.
11.2.3. Preliminary purification of the americium fraction using UTEVA and TRU
resins
11.2.3.1. Transfer each solution from Step 11.2.1.4 into the appropriate
funnel by pouring or by using a plastic transfer pipette. Allow
solution to pass through both cartridges at a flow rate of ~1
mL/min.
11.2.3.2. Add 5 mL of 3-MHNO3 to each beaker (from Step 11.2.1.4) as a
rinse and transfer each solution into the appropriate funnel (the
flow rate can be adjusted to ~3 mL/min).
11.2.3.3. Add 5 mL of 3-M HNOs into each funnel as a second column
rinse (flow rate ~3 mL/min).
11.2.3.4. Separate UTEVA cartridge from TRU cartridge. Discard
UTEVA cartridge and the effluent collected so far. Place new
funnel on the TRU cartridge.
11.2.4. Final americium separation using TRU cartridge
Note: Steps 11.2.4.1 to 11.2.4.3 may be omitted if the samples are known not to contain
plutonium
11.2.4.1. Pipette 5 mL of 2-M HNO3 into each TRU cartridge from Step
11.2.3.4. Allow to drain.
11.2.4.2. Pipette 5 mL of 2-M HNO3 - 0.1-M NaNO2 directly into each
cartridge, rinsing each cartridge reservoir while adding the 2-M
HNO3-0.1-MNaNO2.
IMPORTANT: The flow rate for the cartridge should be adjusted to ~1
mL/min for this step.
Note: Sodium nitrite is used to oxidize any Pu+3 to Pu+4 and enhance the
Pu/Am separation.
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Americium-241 in Water: Rapid Method for High-Activity Samples
11.2.4.3. Allow the rinse solution to drain through each cartridge.
11.2.4.4. Add 5 mL of 0.5-M HNO3 to each cartridge and allow it to drain.
Note: 0.5-M HNO3 is used to lower the nitrate concentration prior to
conversion to the chloride system.
11.2.4.5. Discard the load and rinse solutions to waste.
11.2.4.6. Ensure that clean, labeled tubes (at least 25-mL capacity) are
placed in the tube rack.
11.2.4.7. Add 3 mL of 9-M HC1 to each cartridge to convert to chloride
system. Collect eluate.
11.2.4.8. Add 20 mL of 4-M HC1 to elute americium. Collect eluate in the
same tube.
11.2.4.9. Transfer the combined eluates from Steps II.2 A.I and 11.2.4.8
to a 50-mL beaker.
11.2.4.10. Rinse tube with a few milliliters of water and add to the same
beaker.
11.2.4.11. Evaporate samples to near dryness.
Important: Do not bake the residue.
11.2.4.12. Allow the beaker to cool slightly and then add a few drops of
concentrated HC1 followed by 1 mL of water.
11.2.4.13. Transfer the solution from Step 11.2.4.12 to a 10-mL plastic
culture tube. Wash the original sample vessel twice with 1-mL
washes of 1M HC1. Transfer the washings to the culture tube.
Mix by gently swirling the solution in the tube.
11.2.4.14. Proceed to neodymium fluoride microprecipitation in Step 11.3.
11.2.4.15. Discard the TRU cartridge.
11.3. Preparation of the Sample Test Source
Note: Instructions below describe preparation of a single Sample Test Source. Several STSs can
be prepared simultaneously if a multi-channel vacuum box (whale apparatus) is available.
11.3.1. Add 100 jiL of the neodymium carrier solution to the tube from Step
11.2.4.14 with a micropipette. Gently swirl the tube to mix the solution.
11.3.2. Add 10 drops (0.5 mL) of concentrated HF to the tube and mix well by
gentle swirling.
11.3.3. Cap the tube and place it in a cold-water bath for at least 30 minutes.
11.3.4. Insert the polysulfone filter stem in the 250-mL vacuum flask. Place the
stainless steel screen on top of the fitted plastic filter stem.
11.3.5. Place a 25-mm polymeric filter face up on the stainless steel screen. Center
the filter on the stainless steel screen support and apply vacuum. Wet the
filter with 100% ethanol, followed by filtered Type I water.
241
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Caution: There is no visible difference between the two sides of the filter. If the filter is
turned over accidentally, it is recommended that the filter be discarded and a fresh
one removed from the container.
11.3.6. Lock the filter chimney firmly in place on the filter screen and wash the
filter with additional filtered Type I water.
11.3.7. Pour 5.0 mL of neodymium substrate solution down the side of the filter
chimney, avoiding directing the stream at the filter. When the solution
passes through the filter, wait at least 15 seconds before the next step.
11.3.8. Repeat Step 11.3.7 with an additional 5.0 mL of the substrate solution.
11.3.9. Pour the sample from Stepl 1.3.3 down the side of the filter chimney and
allow the vacuum to draw the solution through.
11.3.10. Rinse the tube twice with 2 mL of 0.58 M HF, stirring each wash briefly
using a vortex mixer, and pouring each wash down the side of the filter
chimney.
11.3.11. Repeat rinse using 2 mL of filtered Type I water once.
11.3.12. Repeat rinse using 2 mL of 80% ethyl alcohol once.
Note: Steps 11.3.10 and 11.3.12 were shown to improve the FWHM in the alpha
spectrum, providing more consistent peak resolution.
11.3.13. Wash any drops remaining on the sides of the chimney down toward the
filter with a few milliliters of 80% ethyl alcohol.
Caution: Directing a stream of liquid onto the filter will disturb the distribution of the
precipitate on the filter and render the sample unsuitable for a-spectrometry
resolution.
11.3.14. Without turning off the vacuum, remove the filter chimney.
11.3.15. Turn off the vacuum to remove the filter. Di scard the filtrate to waste for
future disposal. If the filtrate is to be retained, it should be placed in a plastic
container to avoid dissolution of the glass vessel by dilute HF.
11.3.16. Place the filter on a properly labeled mounting disc. Secure with a mounting
ring or other device that will render the filter flat for counting.
11.3.17. Let the sample air-dry for a few minutes and when dry, place in a container
suitable for transfer and submit for counting.
Note: Other methods for STS preparation, such as electroplating or
microprecipitation with cerium fluoride, may be used in lieu of the neodymium
fluoride microprecipitation, but any such substitution must be validated as described
in Section 1.4.
12. Data Analysis and Calculations
12.1. Equation for determination of final result, combined standard uncertainty, and
radiochemical yield (if requested):
The activity concentration of an analyte and its combined standard uncertainty are
calculated using the following equations:
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Americium-241 in Water: Rapid Method for High-Activity Samples
VaxRtxDaxIa
and
= )x .
2222
.
V2xR2xD2xI2 a A2 V2 R2
a i a a V t « t
where:
= activity concentration of the analyte at time of count, (pCi/L)
^4t = activity of the tracer added to the sample aliquant at its reference
date/time, (pCi)
Ra = net count rate of the analyte in the defined region of interest (ROI),
in counts per second
Rt = net count rate of the tracer in the defined ROI, in counts per second
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
Z)a = correction factor for decay of the analyte from the time of sample
collection (or other reference time) to the midpoint of the counting
period, if required
/t = 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(ACz) = combined standard uncertainty of the activity concentration of the
analyte (pCi/L)
u(Ai) = standard uncertainty of the activity of the tracer added to the
sample (pCi)
w(Fa) = standard uncertainty of the volume of sample aliquant (L)
u(Ra) = standard uncertainty of the net count rate of the analyte in counts
per second
u(Rt) = standard uncertainty of the net count rate of the tracer in counts per
second
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 (uc(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
that 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.
Note: The alpha spectrum of americium isotopes should be examined carefully and the ROI
reset manually, if necessary, to minimize the spillover of 241Am peak into the 243Am peak
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12.1.1. The net count rate of an analyte or tracer and its standard uncertainty can
be calculated using the following equations:
_ Cx Cbx
and
1C +1 Ch +1
- bx
where:
Rx = net count rate of analyte or tracer, in counts per second
Cx = sample counts in the analyte or the tracer ROI
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 second1
If the radiochemical yield of the tracer is requested, the yield and its combined
standard uncertainty can be calculated using the following equations:
RY =
and
0.037x4
where:
RY = radiochemical yield of the tracer, expressed as a fraction
Rt = net count rate of the tracer, in counts per second
At = activity of the tracer added to the sample (pCi)
Dt = correction factor for decay of the tracer from its reference date and
time to the midpoint of the counting period
/t = probability of a emission in the defined ROI per decay of the tracer
(Table 17.1)
s = detector efficiency, expressed as a fraction
uc(RY) = combined standard uncertainty of the radiochemical yield
1 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.
241
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u(Ri) = 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
12.1.2. If the critical level concentration (Sc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations:2
S =
0.4x -^-1 +0.677x 1 + ^- +1.645x
AtxDtx It
tsxVaxRtxDax!a
MDC =
2.71x
+ 3.29X
txVxRxDxI
x Dt x It
where:
Rba =
background count rate for the analyte in the defined ROI, in counts
per second
12.2. Results Reporting
12.2. 1 . The following items should be reported for each result: volume of sample
used; yield of tracer and its uncertainty; and full width at half maximum
(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.
12.2.2.2. If solid material was filtered from the solution and analyzed
separately, the results of that analysis should be reported separately
as pCi/L of the original volume from which the solids were filtered
if no other guidance is provided on reporting of results for the
solids. For example:
1 Am for Sample 12-1-99:
Filtrate Result: 12.8 ± 1.5 pCi/L
Filtered Residue Result: 2.5 ± 0.3 pCi/L
241
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. The formulations presented here assume an error rate of a = 0.05, ft = 0.05 (with z\-a = 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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13. Method Performance
13.1. Method validation results are to be reported as an attachment.
13.1.1. Expected turnaround time per batch of 14 samples plus QC, assuming
microprecipitations for the whole batch are performed simultaneously using
a vacuum box system:
13.1.2. For an analysis of a 200-mL sample aliquant, sample preparation and
digestion should take 3.5 h.
13.1.3. Purification and separation of the americium fraction using cartridges and
vacuum box system should take 2.5 h.
13.1.4. Sample evaporation to near dryness should take ~ 30 minutes.
13.1.5. The last Stepof source preparation takes ~1 h.
13.1.6. A 1-3 h counting time is sufficient to meet the MQOs listed in 9.3 and 9.4,
assuming detector efficiency of 0.2-0.3, and radiochemical yield of at least
0.5. Longer counting time may be necessary to meet these MQOs if detector
efficiency is lower.
13.1.7. Data should be ready for reduction between 8.5 and 10.5 h after beginning
of analysis.
14. Pollution Prevention: This 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 americium fraction.
15. Waste Management
15.1. Types of waste generated per sample analyzed
15.1.1. If Ca3(PC>4)2 coprecipitation is performed, approximately 100-1000 mL of
decanted solution that is pH neutral are generated.
15.1.2. Approximately 35 mL of acidic waste from loading and rinsing the two
extraction columns are generated.
15.1.3. Approximately 35 mL of acidic waste from microprecipitation method for
source preparation, contains 1 mL of HF and ~ 8 mL ethanol.
15.1.4. Unless processed further, the UTEVA cartridge may contain isotopes of
uranium, neptunium, and thorium, if any of these were present in the sample
originally.
15.1.5. Unless processed further, the TRU cartridge may contain isotopes of
plutonium if any of them were present in the sample originally.
15.2. Evaluate all waste streams according to disposal requirements by applicable
regulations.
16. References
16.1. ACW03 VBS, Rev. 1.6, "Americium, Plutonium, and Uranium in Water (with
Vacuum Box System)," Eichrom Technologies, Inc., Lisle, Illinois (February 2005).
16.2. G-03, V. 1 "Microprecipitation Source Preparation for Alpha Spectrometry," HASL-
300, 28th Edition, (February 1997).
241
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Americium-241 in Water: Rapid Method for High-Activity Samples
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. VBS01, Rev.1.3, "Setup and Operation Instructions for Eichrom's Vacuum Box
System (VBS)," Eichrom Technologies, Inc., Lisle, Illinois (January 2004).
16.5. U.S. Environmental Protection Agency (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.
Available at: www.epa.gov/narel/incident_guides.html.
16.6. 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 at: www.epa.gov/radiation/
marlap/index.html.
16.7. ASTM Dl 193, "Standard Specification for Reagent Water" ASTM Book of
Standards 11.01, current version, ASTM International, West Conshohocken, PA.
241
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17. Tables, Diagrams, Flow Charts, and Validation Data
17.1. Tables [including major radiation emissions from all radionuclides separated]
Table 17.1 Alpha Particle Energies and Abundances of Importance
[i]
Nuclide
241Am
243Am
Half-Life
(Years)
432.6
7.37xl03
>,
(s")
5.077x10""
2.98xlO~12
Abundance
0.848
0.131
0.0166
0.871
0.112
0.0136
a Energy
(MeV)
5.486
5.443
5.388
5.275
5.233
5.181
[ ]Only the most abundant particle energies and abundances have been noted here.
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Americium-241 in Water: Rapid Method for High-Activity Samples
17.2. Ingrowth Curves and Ingrowth Factors
This section intentionally left blank
17.3. Spectrum from a Processed Sample
110 •
100 -
90
« 70 -
I 60 -
50 •
40 -
30 -
20 •
10 •
Am-243
Am-241
3011 3311 3611 3911 4211 4511 4811 5111 5411 5711 8011 6311 6611 6911 7211 7511 7811
Energy (keV)
17.2 Decay Scheme
241 Am and 243Am Decay Scheme
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17.4. Flowchart
Sample preparation (Step 11.1)
1. Add 243Am tracer
2. Digestion or calcium phosphate
co-precipitation (2—3 hours)
Preparation for cartridge (Step 11.2.1)
1. Dissolve phosphate
2. Add sulfamate, thiocyanate, ascorbic
acid (5 minutes)
Set up of UTEVA and TRU cartridges
in tandem using VBS (Step 11.2.2)
1. Assembly
2. Prep with 5 ml 3 M HNO3 @ 1 mL/min
Load the cartridge (Step 11.2.3)
Sample: 20 ml @ 1 mL/min
Rinse: 5 ml 3 M HNO3 @ 3 mL/min
2nd rinse: 5mL3M HNO3
(~ 25 minutes)
Separate cartridges (Step 11.2.3.4)
I
UTEVA cartridge to waste
Effluent to waste
(Step 11.2.3.4)
TRU cartridge for processing
Attach fresh funnel to the cartridge
Elapsed
time
-3.5 hours
~6 hours
Separation scheme and timeline for determination of Am in water samples
Parti
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Am -Page 19
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+
Discard load and rinse
effluents (Step 11. 2. 4. 5)
*
Discard TRU cartridge
(Step 11. 2. 4. 15)
Caution: may contain Pu
*
Discard filtrates and washes
(Step 11. 3. 15)
Convert Pu '3 to PIT" (Steps 11.2.4.1-3)
1 . 5 ml 2 M HNO 3 @ 3 mUmin
2. 5mL2MHN03+0.1 MNaN02@1 m Urn in
3. 5 mL 0.5 M HNO 3 @ 1 m Urn in
1
1
/
Strip Am+3 from the cartridge (Steps 1 1.2.4.6-14
1 . Add 3 mL 9 M HCI @ 1 m Urn in
2. Add 20 ml 4 M HCI @ 1 mUmin
3. Evaporate eluate and re dissolve
~ 1 hour
I
1
Microprecipitation (Step 11.3)
1 . Add NdF3 carrier and wait 30 min
2. Filter, dry. mount
(1 hour)
|
\
rs^p ifptT]
) riot
A^ present _J
T Count sample test source (STS) "1
LX^__^OM::3hqU[S _sS
6.5 hours hours
-7.5 hours
8.5 to 10.5 hours
Separation scheme and timeline for determination of 2* Am in water samples
Part 2
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Americium-241 in Water: Rapid Method for High-Activity Samples
Appendix
Composition of Atlanta Drinking Water Used for this Study
Metals by ICP-AES
Silicon
Aluminum
Barium
Calcium
Iron
Magnesium
Potassium
Sodium
Inorganic Anions
Chloride
Sulfate
Nitrogen, Nitrate (as N)
Carbon Dioxide
Bicarbonate Alkalinity
Carbonate Alkalinity
Radionuclide
Uranium 234, 235, 238
Plutonium 238, 239/240
Americium 24 1
Strontium 90
Radium 226***
Concentration (mg/L)*
3.18
<0.200
0.0133
9.38
<0.100
<0.500
<0.500
<0.500
12.7
15.6
1.19
23.8
<3.00
Concentration (pCi/L)**
<0.01,<0.01,<0.01
<0.02, <0.02
<0.02
<0.3
0.11 ±0.27
-0.30 ±0.45
Note: Analyses conducted by independent laboratories.
* Values below the reporting level are presented as less than (<) values.
No measurement uncertainty was reported with values greater than the "Reporting
Level."
** Reported values represent the calculated minimum detectable concentration (MDC)
for the radionuclide(s).
*** Two samples analyzed.
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www.epa.gov
February 2010
Revision 0
Rapid Radiochemical Method for
Plutonium-238 and Plutonium-239/240
in Water
for Environmental Restoration Following
Homeland Security Events
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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PLUTONIUM-238 AND PLUTONIUM-239/240 IN WATER:
RAPID METHOD FOR HIGH-ACTIVITY SAMPLES
1. Scope and Application
1.1. The method will be applicable to samples where contamination is either from known or
unknown origins. If any filtration of the sample is performed prior to starting the
analysis, those solids should be analyzed separately. The results from the analysis of
these solids should be reported separately (as a suspended activity concentration for the
water volume filtered), but identified with the filtrate results.
1.2. The method is specific for 238Pu and 239/240Pu in drinking water and other aqueous
samples.
1.3. The method uses rapid radiochemical separation techniques for determining alpha-
emitting plutonium isotopes in water samples following a nuclear or radiological
incident. Although the method can detect concentrations of 238Pu and 239/240Pu on the
same order of magnitude as methods used for the Safe Drinking Water Act (SDWA),
this method is not a substitute for SDWA-approved methods for isotopic plutonium.
OIQ Ozin
1.4. The method cannot distinguish between Pu and Pu and any results are reported as
the total activity of the two radionuclides.
1.5. The method is capable of achieving a required method uncertainty for 238Pu or 239/240pu
of 1.9 pCi/L at an analytical action level of 15 pCi/L. To attain the stated measurement
quality objectives (MQOs) (see Sections 9.3 and 9.4), a sample volume of
approximately 200 mL and count time of at least 1 hour are recommended. The sample
turnaround time and throughput may vary based on additional project MQOs, the time
for analysis of the final counting form and initial sample volume. 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 (EPA 2009, reference 16.5).
1.6. The method is intended to be used for water samples that are similar in composition to
drinking water. The rapid plutonium method was 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 (EPA 2009,
reference 16.5) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP 2004, reference 16.6). The matrix used for the
determination of plutonium was drinking water from Atlanta, GA. See table in the
01£
appendix for a listing of the chemical constituents of the water. Although only Pu
was used, the method is valid for 239/240pu as well, as they are chemically identical and
there are no differences in the method that would be used to determine these isotopes.
Note that this method cannot distinguish between 239Pu and 240Pu and only the sum of
the activities of these two isotopes can be determined.
1.7. Multi-radionuclide analysis using sequential separation may be possible using this
method in conjunction with other rapid methods.
1.8. This method is applicable to the determination of soluble plutonium. This method is not
applicable to the determination of plutonium isotopes contained in highly insoluble
paniculate matter possibly present in water samples contaminated as a result of a
radiological dispersion device (RDD) or IND event. Solid material filtered from
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
solutions to be analyzed for plutonium should be treated separately by a method that
can dissolve high-temperature-fired plutonium oxides such as a solid fusion technique.
2. Summary of Method
2.1. This method is based on the sequential use of two chromatographic extraction resins to
isolate and purify plutonium by removing interfering radionuclides as well as other
components of the matrix in order to prepare the plutonium fraction for counting by
alpha spectrometry. The method utilizes vacuum-assisted flow to improve the speed of
the separations. Prior to using the extraction resins, a water sample is filtered as
necessary to remove any insoluble fractions, equilibrated with 242Pu tracer, and
concentrated by either evaporation or Ca3(PO/t)2 coprecipitation. The sample test source
(STS) is prepared by microprecipitation with NdF3. Standard laboratory protocol for the
use of an alpha spectrometer should be used when the sample is ready for counting.
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 decisionmaker to choose one of the alternative
actions.
3.3. Analytical Decision Level (ADL). The analytical decision level refers to the value that
is less than the AAL and based on the acceptable error rate and the required method
uncertainty.
3.4. 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).
3.5. Multi-Agency Radiological Analytical Laboratory Protocols Manual (MARL AP) (see
Reference 16.6.)
3.6. 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.
3.7. Radiological Dispersal Device (RDD), i.e., a "dirty bomb." This is an unconventional
weapon constructed to distribute radioactive material(s) into the environment either by
incorporating them into a conventional bomb or by using sprays, canisters, or manual
dispersal.
3.8. Required Method Uncertainty (WMR). The required method uncertainty is a target value
for the individual measurement uncertainties, and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method uncertainty
is applicable below an AAL.
3.9. Relative Required Method Uncertainty (
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
3.10. 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: Alpha-emitting radionuclides with irresolvable alpha energies, such as
238Pu (5.50 MeV), 241Am (5.48 MeV), and 228Th (5.42 MeV), that must be chemically
separated to enable measurement. This method separates these radionuclides
effectively. The significance of peak overlap will be determined by the individual
detector's alpha energy resolution characteristics and the quality of the final precipitate
that is counted.
4.2. Non-Radiological: Very high levels of competing higher valence anions (greater than
divalent such as phosphates) will lead to lower yields when using the evaporation
option due to competition with active sites on the resin. If higher valence anions are
present phosphate, the precipitation may need to be used initially in place of
evaporation. If calcium phosphate coprecipitation is performed to collect plutonium
(and other potentially present actinides) from large-volume samples, the amount of
phosphate added to coprecipitate the actinides (in Step 11.1.4.3) should be reduced to
accommodate the sample's high phosphate concentration.
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.
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. Hot particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles" (DRPs), will
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 or finer filter
will minimize the presence of these particles.
5.2.1.2. 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 causing contamination.
5.2.1.3. Filter media should be individually surveyed for the presence of these
particles, and this information should be reported with the final sample
results.
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.
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Appropriate personal protective equipment (PPE) must be used in strict accordance
with the laboratory safety program specification.
6. Equipment and Supplies
6.1. Analytical balance with 0.01-g readability, or better.
6.2. Cartridge reservoirs, 10- or 20-mL syringe style with locking device, or equivalent.
6.3. Centrifuge able to accommodate 250-mL flasks.
6.4. Centrifuge flasks, 250-mL capacity.
6.5. Filter with 0.45-|im membrane.
6.6. Filter apparatus with 25-mm-diameter polysulfone filtration chimney, stem support, and
stainless steel support. A single-use (disposable) filter funnel/filter combination may be
used, to avoid cross-contamination.
6.7. 25-mm polypropylene filter, 0.1-um pore size, or equivalent.
6.8. Stainless steel planchets or other sample mounts able to hold the 25-mm filter.
6.9. Tweezers.
6.10. 100-uL pipette or equivalent and appropriate plastic tips.
6.11. 10-mL plastic culture tubes with caps.
6.12. Vacuum pump or laboratory vacuum system.
6.13. Tips, white inner, Eichrom part number AC-1000-IT, or equivalent.
6.14. Tips, yellow outer, Eichrom part number AC-1000-OT, or equivalent.
6.15. Vacuum box, such as Eichrom part number AC-24-BOX, or equivalent.
6.16. Vortex mixer.
6.17. Miscellaneous laboratory ware of plastic or glass; 250- and 500-mL capacities.
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. All solutions used in microprecipitation should be prepared with water filtered through a 0.45-um
(or better) filter.
7.1. Ammonium hydrogen oxalate (0.1M): Dissolve 6.3 g of oxalic acid (H2C2O4-2H2O)
and 7.1 g of ammonium oxalate ((NH4)2C2O4-H2O) in 900 mL of water and dilute to 1
L with water.
7.2. Ammonium hydrogen phosphate (3.2 M): Dissolve 106 g of (NH4)2HPO4 in 200 mL of
water, heat gently to dissolve and dilute to 250 mL with water.
7.3. Ammonium hydroxide: Concentrated NH/tOH, available commercially.
7.4. Ammonium thiocyanate indicator (1 M): Dissolve 7.6 g of ammonium thiocyanate
(NFLSCN) in 90 mL of water and dilute to 100 mL with water. An appropriate amount
of sodium thiocyanate (8.1 g) or potassium thiocyanate (9.7 g) may be substituted for
ammonium thiocyanate.
7.5. Ascorbic acid (1 M) - Dissolve 17.6 g of ascorbic acid (CeHgOe) in 90 mL of water and
dilute to 100 mL with water. Prepare weekly.
7.6. Calcium nitrate (0.9M): Dissolve 53 g of calcium nitrate tetrahydrate (Ca(NO3)2'4H2O)
in 100 mL of water and dilute to 250 mL with water.
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7.7. Ethanol, 100%: Anhydrous C2H5OH, available commercially.
7.7.1. Ethanol (-80% v/v): Mix 80 mL 100% ethanol and 20 mL water.
7.8. Ferrous sulfamate (0.6M): Add 57 g of sulfamic acid (NH2SO3H) to 150 mL of water,
heat to 70°C, slowly add 7 g of iron powder (< 100 mesh size) while heating and
stirring (magnetic stirrer should be used) until dissolved (may take as long as two
hours). Filter the hot solution (using a qualitative filter), transfer to flask and dilute to
200 mL with water. Prepare fresh weekly.
7.9. Hydrochloric acid (12 M): Concentrated HC1, available commercially.
7.9.1. Hydrochloric acid (4 M): Add 333 mL of concentrated HC1 to 500 mL of water
and dilute to 1 L with water
7.9.2. Hydrochloric acid (1 M): Add 83 mL of concentrated HC1 to 500 mL of water
and dilute with water to 1 L.
7.9.3. Hydrochloric acid (9 M): Add 750 mL of concentrated HC1 to 100 mL of water
and dilute to 1 L with water.
7.10. Hydrochloric acid (4 M) - hydrofluoric acid (0.1 M): Add 333 mL of concentrated HC1
and 3.6 mL of concentrated HF to 500 mL of water and dilute to 1 L with water.
Prepare fresh daily.
7.11. Hydrofluoric acid (28M): Concentrated HF, available commercially.
7.11.1. HF (0.58M): Add 20 mL of concentrated HF to 980 mL of filtered
demineralized water and mix. Store in a plastic bottle.
7.12. Neodymium standard solution (1000 ug/mL) may be purchased from a supplier of
standards for atomic spectroscopy.
7.13. Neodymium carrier solution (0.50 mg/mL): Dilute 10 mL of the neodymium standard
solution (7.12) to 20.0 mL with filtered demineralized water. This solution is stable.
7.14. Neodymium fluoride substrate solution (10 jig/mL): Pipette 5 mL of neodymium
standard solution (7.12) into a 500-mL plastic bottle. Add 460 mL of 1 M HC1 to the
plastic bottle. Cap the bottle and shake to mix. Measure 40 mL of concentrated HF acid
in a plastic graduated cylinder and add to the bottle. Recap the bottle and shake to mix
thoroughly. This solution is stable for up to six months.
7.15. Nitric acid (16 M): Concentrated HNO3, available commercially.
7.15.1. Nitric acid (0.5 M): Add 32 mL of concentrated HNO3 to 900 mL of water and
dilute to 1 L with water.
7.15.2. Nitric acid (2 M): Add 127 mL of concentrated HNO3 to 800 mL of water and
dilute to 1 L with water.
7.15.3. Nitric acid (3 M): Add 191 mL of concentrated HNO3 to 700 mL of water and
dilute to 1 L with water.
7.16. Nitric acid (2M) - sodium nitrite (0.1 M) solution: Add 32 mL of concentrated HNO3
(7.15) to 200 mL of water and mix. Dissolve 1.7 g of sodium nitrite (NaNC^) in the
solution and dilute to 250 mL with water. Prepare fresh daily.
7.17. Nitric acid (3 M) - aluminum nitrate (1.0 M) solution: Dissolve 213 g of anhydrous
aluminum nitrate (A1(NO3)3) in 700 mL of water, add 190 mL of concentrated HNO3
(7.15) and dilute to 1 L with water. An appropriate quantity of aluminum nitrate
nonahydrate (375 g) may be substituted for anhydrous aluminum nitrate.
7.18. Phenolphthalein solution: Dissolve 1 g phenolphthalein in 100 mL 95% isopropyl
alcohol and dilute with 100 mL of water.
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
7.19. Plutonium-242 tracer solution - 6-10 dpm of 242Pu per aliquant, activity added known
to at least 5% (combined standard uncertainty of no more than 5%).
Note: If it is suspected that 242Pu may be present in the sample, 236Pu tracer would be an acceptable
substitute.
7.20. TRU Resin - 2-mL cartridge, 50- to 100-|j,m mesh size, Eichrom part number TR-R50-
S and TR-R200-S, or equivalent.
7.21. UTEVA Resin - 2-mL cartridge, 50- to 100-|j,m mesh size, Eichrom part number UT-
R50-S and UT-R200-S, or equivalent.
8. Sample Collection, Preservation, and Storage
8.1. Samples should be collected in 1-L plastic containers.
8.2. No sample perseveration is required if sample is delivered to the laboratory within 3
days of sampling date/time.
8.3. If the dissolved concentration of plutonium is sought, the insoluble fraction must be
removed by filtration before preserving with acid.
8.4. If the sample is to be held for more than three days, HNOs shall be added until pH<2.
9. Quality Control
9.1. 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 manual and
procedures shall be used to determine acceptable performance for this method.
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 laboratory 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 may be included as a batch quality control sample if
there is concern that matrix interferences may compromise chemical yield
measurements or overall data quality.
9.2. The source preparation method should produce a sample test source that produces a
spectrum with the full width at half maximum (FWHM) of 50-100 keV for each peak in
the spectrum. Precipitate reprocessing should be considered if this range of FWHM
cannot be achieved.
9.3. This method is capable of achieving a UMR of 1.9 pCi/L at or below an action level of 15
pCi/L. This may be adjusted if the event specific MQOs are different.
9.4. This method is capable of achieving a required ^MR of 13% above 15 pCi/L. This may
be adjusted if the event specific MQOs are different.
9.5. This method is capable of achieving a required minimum detectable concentration
(MDC)of 1.5pCi/L.
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10. Calibration and Standardization
10.1. Set up the alpha spectrometry system according to the manufacturer's
recommendations. The energy range of the spectrometry system should at least include
the region between 3 and 8 MeV.
10.2. Calibrate each detector used to count samples according to ASTM Standard Practice
D7282, Section 18, "Alpha Spectrometry Instrument Calibrations" (see reference 16.3).
10.3. Continuing Instrument Quality Control Testing shall be performed according to ASTM
Standard Practice D7282, Sections 20, 21, and 24.
1 1 . Procedure
11.1. Water Sample Preparation:
11.1.1. As required, filter the 100-200 mL sample aliquant through a 0.45-|im filter and
collect the sample in an appropriate size beaker.
1 1.1.2. Acidify the sample with concentrated HNOs, to a pH of < 2.0 by adding enough
HNOs. This usually requires about 2 mL of concentrated HNOs per 1000 mL of
sample.
1 1.1.3. Add 6-10 dpm of 242Pu as a tracer, following laboratory protocol. The tracer
should be added right before you are planning to proceed to Step 1 1 . 1 .4 or
11.1.5. If the sample solution with the added tracer is not processed right away,
isotopic exchange may be compromised and the analytical results will be
incorrect.
Note: For a sample approximately 100 mL or less, the evaporation option is recommended.
Proceed to Step 11.1.5. Otherwise go to Step 11.1.4.
11.1.4. Calcium phosphate coprecipitation option
11.1.4.1. Add 0.5 mL of 0.9-M Ca(NO3)2 to each beaker. Place each beaker on
a hot plate, cover with a watch glass, and heat until boiling.
11.1 .4.2. Once the sample boils, take the watch glass off the beaker and lower
the heat.
11.1.4.3. Add 2-3 drops of phenolphthalein indicator and 200 \\L of 3 .2-M
(NH4)2HPO4 solution.
11.1 .4.4. Add enough concentrated NiLiOH with a squeeze bottle to reach the
phenolphthalein end point and form Ca3(PO4)2 precipitate. NH/tOH
should be added very slowly. Stir the solution with a glass rod.
Allow the sample to heat gently to digest the precipitate for another
20-30 minutes.
11.1 .4.5. If the sample volume is too large to centrifuge the entire sample,
allow precipitate to settle until solution can be decanted (30 minutes
to 2 hours) and go to Step 1 1 . 1 .4.7.
11.1 .4.6. If the volume is small enough to centrifuge, go to Step 1 1 . 1 .4.8.
1 1 . 1 .4.7. Decant supernatant solution and discard to waste.
11.1.4.8. Transfer the precipitate to a 250-mL centrifuge tube (rinsing the
original container with a few milliliters of water to complete the
precipitate transfer) and centrifuge the precipitate for approximately
10 minutes at 2000 rpm.
11.1 .4.9. Decant supernatant solution and discard to waste.
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11.1.4.10. Wash the precipitate with an amount of water approximately twice
the volume of the precipitate. Mix well using a stirring rod, breaking
up the precipitate if necessary. Centrifuge for 5-10 minutes at 2000
rpm. Discard the supernatant solution.
11.1.4.11. Dissolve precipitate in approximately 5 mL of concentrated HNOs.
Transfer solution to a 100-mL beaker. Rinse centrifuge tube with 2-
3 mL of concentrated HNOs and transfer to the same beaker.
Evaporate solution to dryness and go to Step 11.2.
11.1.5. Evaporation option to reduce volume and to digest organic components
11.1.5.1. Evaporate sample to less than 50 mL and transfer to a 100-mL
beaker.
Note: For some water samples, CaSO4 formation may occur during
evaporation. If this occurs, use the Ca3(PO4)2 precipitation option in Step
11.1.4.
11.1.5.2. Gently evaporate the sample to dryness and redissolve in
approximately 5 mL of concentrated HNOs.
11.1.5.3. Repeat Step 11.1.5.2 two more times, evaporate to dryness, and go to
Step 11.2.
11.2. Actinide Separations using Eichrom resins
11.2.1. Redissolve Ca3(PO/t)2 residue or evaporated water sample:
11.2.1.1. Dissolve either residue with 10 mL of 3 M HNO3-1.0 M A1(NO3)3.
Note: An additional 5 mL may be necessary if the residue volume is large.
11.2.1.2. Add 2 mL of 0.6-M ferrous sulfamate to each solution. Swirl to mix.
Note: If the additional 5 mL was used to dissolve the sample in Step 11.2.1.1,
add a total of 3 mL of ferrous sulfamate solution.
11.2.1.3. Add 1 drop of 1 -M ammonium thiocyanate indicator to each sample
and mix.
Note: The color of the solution turns deep red due to the formation of a
soluble ferric thiocyanate complex.
11.2.1.4. Add 1 mL of 1-M ascorbic acid to each solution, swirling to mix.
Wait for 2-3 minutes.
Note: The red color should disappear, which indicates reduction of Fe+3 to
Fe+2. If the red color persists, then additional ascorbic acid solution is added
drop-wise with mixing until the red color disappears.
Note: If particles are observed suspended in the solution, centrifuge the
sample. The supernatant solution will be transferred to the column in Step
11.2.3.1. The precipitates will be discarded.
11.2.2. Set up of UTEVA and TRU cartridges in tandem on the vacuum box system
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Note: Steps 11.2.2.1 to 11.2.2.5 deal with a commercially available filtration system. Other
vacuum systems developed by individual laboratories may be substituted here as long as
the laboratory has provided guidance to analysts in their use.
11.2.2.1. Place the inner tube rack (supplied with vacuum box) into the
vacuum box with the centrifuge tubes in the rack. Fit the lid to the
vacuum box system.
11.2.2.2. Place the yellow outer tips into all 24 openings of the lid of the
vacuum box. Fit in the inner white tip into each yellow tip.
11.2.2.3. For each sample solution, fit in the TRU cartridge on to the inner
white tip. Ensure the UTEVA cartridge is locked to the top end of
the TRU cartridge.
11.2.2.4. Lock syringe barrels (funnels/reservoirs) to the top end of the
UTEVA cartridge.
11.2.2.5. Connect the vacuum pump to the box. Turn the vacuum pump on
and ensure proper fitting of the lid.
IMPORTANT: The unused openings on the vacuum box should be sealed.
Yellow caps (included with the vacuum box) can be used to plug unused white
tips to achieve good seal during the separation.
11.2.2.6. Add 5 mL of 3-M HNO3 to the funnel to precondition the UTEVA
and TRU cartridges.
11.2.2.7. Adjust the vacuum pressure to achieve a flow-rate of ~1 mL/min.
IMPORTANT: Unless otherwise specified in the procedure, use a flow rate of
~ 1 mL/min for load and strip solutions and ~ 3 mL/min for rinse solutions.
11.2.3. Preliminary purification of the plutonium fraction using UTEVA and TRU
resins
11.2.3.1. Transfer each solution from Step 11.2.1.4 into the appropriate funnel
by pouring or by using a plastic transfer pipette. Allow solution to
pass through both cartridges at a flow rate of ~1 mL/min.
11.2.3.2. Add 5 mL of 3-MHNO3 to each beaker (from Step 11.2.1.4) as a
rinse and transfer each solution into the appropriate funnel (the flow
rate can be adjusted to ~3 mL/min).
11.2.3.3. Add 5 mL of 3-M FINOs into each funnel as second column rinse
(flow rate ~3 mL/min).
11.2.3.4. Separate UTEVA cartridge from TRU cartridge. Discard UTEVA
cartridge and the effluent collected so far. Place new funnel on the
TRU cartridge.
11.2.4. Final plutonium separation using TRU cartridge
11.2.4.1. Pipette 5 mL of 2-M HNO3 into each TRU cartridge from Step
11.2.3.4. Allow to drain.
11.2.4.2. Pipette 5 mL of 2-M HNO3-0.1-M NaNO2 directly into each
cartridge, rinsing each cartridge reservoir while adding the 2 M
HNO3-0.1-MNaNO2.
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IMPORTANT: The flow rate for the cartridge should be adjusted to ~1
mL/min for this step.
Note: Sodium nitrite is used to oxidize any Pu+3 to Pu+4 and optimize the
separation from other trivalent actinides possibly present in the sample.
11.2.4.3. Allow the rinse solution to drain through each cartridge.
11.2.4.4. Add 5 mL of 0.5-M HNOs to each cartridge and allow it to drain
(flow rate left at ~1 mL/min).
Note: 0.5 M HNO3 is used to lower the nitrate concentration prior to
conversion to the chloride system.
Note: Steps 11.2.4.5 and 11.2.4.6 may be omitted if the samples are known not
to contain americium.
11.2.4.5. Add 3 mL of 9-M HC1 to each cartridge to convert to chloride
system.
11.2.4.6. Add 20 mL of 4-M HC1 to remove americium.
11.2.4.7. Rinse the cartridge with 25 mL of 4-M HC1-0.1-M HF. Discard all
the eluates collected so far to waste (for this step, the flow rate can
be increased to ~3 mL/min).
Note: 4-M HC1 - 0.1-M HF rinse selectively removes any residual Th that
may still be present on the TRU cartridge. The plutonium remains on the
cartridge.
11.2.4.8. Ensure that clean, labeled plastic tubes are placed in the tube rack
under each cartridge.
11.2.4.9. Add 10 mL of 0.1-M ammonium bioxalate (MLJK^C^) to elute
plutonium from each cartridge, reducing the flow rate to ~1 mL/min.
11.2.4.10. Set plutonium fraction in the plastic tube aside for neodymium
fluoride coprecipitation, Step 11.3.
11.2.4.11. Discard the TRU cartridge.
11.3. Preparation of the Sample Test Source
Note: Instructions below describe preparation of a single Sample Test Source. Several STSs can be
prepared simultaneously if a multi-channel vacuum box (whale apparatus) is available.
11.3.1. Add 100 jiL of the neodymium carrier solution to the tube with a
micropipette. Gently swirl the tube to mix the solution.
11.3.2. Add 1 mL of concentrated HF to the tube and mix well by gentle swirling.
11.3.3. Cap the tube and place it in a cold-water bath for at least 30 minutes.
11.3.4. Insert the polysulfone filter stem in the 250-mL vacuum flask. Place the
stainless steel screen on top of the fitted plastic filter stem.
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
11.3.5. Place a 25-mm polymeric filter face up on the stainless steel screen. Center
the filter on the stainless steel screen support and apply vacuum. Wet the filter
with 100% ethanol, followed by filtered Type I water.
Caution: There is no visible difference between the two sides of the filter. If the filter is
turned over accidentally, it is recommended that the filter be discarded and a fresh one
removed from the box.
11.3.6. Lock the filter chimney firmly in place on the filter screen and wash the filter
with additional filtered Type I water.
11.3.7. Pour 5.0 mL of neodymium substrate solution down the side of the filter
chimney, avoiding directing the stream at the filter. When the solution passes
through the filter, wait at least 15 seconds before the next step.
11.3.8. Repeat Step 11.3.7 with an additional 5.0 mL of the substrate solution.
11.3.9. Pour the sample from Step 11.3.3 down the side of the filter chimney and
allow the vacuum to draw the solution through.
11.3.10. Rinse the tube twice with 2 mL of 0.58-M HF, stirring each wash briefly using
a vortex mixer, and pouring each wash down the side of the filter chimney.
11.3.11. Repeat rinse, using 2 mL of filtered Type I water once.
11.3.12. Repeat rinse using 2 mL of 80% ethyl alcohol once.
11.3.13. Wash any drops remaining on the sides of the chimney down toward the filter
with a few milliliters of 80% ethyl alcohol.
Caution: Directing a stream of liquid onto the filter will disturb the distribution of the
precipitate on the filter and render the sample unsuitable for a-spectrometry resolution.
11.3.14. Without turning off the vacuum, remove the filter chimney.
11.3.15. Turn off the vacuum to remove the filter. Discard the filtrate to waste for
future disposal. If the filtrate is to be retained, it should be placed in a plastic
container to avoid dissolution of the glass vessel by dilute HF.
11.3.16. Place the filter on a properly labeled mounting disc, secure with a mounting
ring or other device that will render the filter flat for counting.
11.3.17. Let the sample air-dry for a few minutes and when dry, place in a container
suitable for transfer and submit for counting.
Note: Other methods for STS preparation, such as electroplating or microprecipitation
with cerium fluoride, may be used in lieu of the neodymium fluoride microprecipitation,
but any such substitution must be validated as described in Section 1.5
12. Data Analysis and Calculations
12.1. Equation for determination of final result, combined standard uncertainty and
radiochemical yield (if required):
The activity concentration of an analyte and its combined standard uncertainty are
calculated using the following equations:
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_AtxRaxDtxIt
and
where:
ACn = activity concentration of the analyte at time of count, in picocuries per liter
(pCi/L)
At = activity of the tracer added to the sample aliquant at its reference date/time
(pCi)
RH = net count rate of the analyte in the defined region of interest (ROI), in
counts per second
Rt = net count rate of the tracer in the defined ROI, in counts per second
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
(if required)
/t = 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)
w(Fa) = standard uncertainty of the volume of sample aliquant (L)
u(Ra) = standard uncertainty of the net count rate of the analyte (s^1)
u(Rt) = standard uncertainty of the net count rate of the tracer (s^1)
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 (wc(y4Ca)) 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 that
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.
12.1.1. The net count rate of an analyte or tracer and its standard uncertainty are
calculated using the following equations:
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
and
C +1 C+l
where:
Rx = net count rate of analyte or tracer, in counts per second
Cx = sample counts in the analyte or the tracer ROI
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 second1
If the radiochemical yield of the tracer is requested, the yield and its combined standard
uncertainty can be calculated using the following equations:
RY= ^
0.037x4 xDtx!txs
and
where:
RY = radiochemical yield of the tracer, expressed as a fraction
Rt = net count rate of the tracer, in counts per second
At = activity of the tracer added to the sample (pCi)
Dt = correction factor for decay of the tracer from its reference date and
time to the midpoint of the counting period
/t = probability of a emission in the defined ROI per decay of the tracer
(Table 17.1)
e = detector efficiency, expressed as a fraction
uc(RY) = 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)
1 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.
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u(s) = standard uncertainty of the detector efficiency
12.1.2. If the critical level concentration (Sc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations: 2
s=±
(t "1 ( t
0.4x -^--1 +0.677x 1 + ^-
L u J I **
"I If t ( O
+ 1.645x 1(7?. ^, +0.4)x^-x 1 + ^-
) V ^ I rJJ
x At x Dt x It
tsxVaxRtxDax!a
MDC = ^
2.71xfl + ^] + 3.29x K./.xfl + ^l
v 'by V v 'by
x ^4t x Z)t x 7t
txVxRxDxI
where:
= 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.
12.2.2.2. If solid material was filtered from the solution and analyzed
separately, the results of that analysis should be reported separately as
pCi/L of the original volume from which the solids were filtered if no
other guidance is provided on reporting of results for the solids. For
example:
239/240Pu for Sample 12-1-99:
Filtrate Result: 12.8 ± 1.5 pCi/L
Filtered Residue Result: 2.5 ± 0.3 pCi/L
13. Method Performance
13.1. Method validation results are to be reported.
13.2. Expected turnaround time per batch 14 samples plus QC, assuming microprecipitations
for the whole batch are performed simultaneously using a vacuum box system:
13.2.1. For an analysis of a 200 mL sample aliquant, sample preparation and digestion
should take -3.5 h.
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. The formulations presented here assume an error rate of a = 0.05, ft = 0.05 (with z\-a = 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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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
13.2.2. Purification and separation of the plutonium fraction using cartridges and
vacuum box system should take ~2 h.
13.2.3. The sample test source preparation step takes ~1 h.
13.2.4. A one-hour counting time should be sufficient to meet the MQOs listed in 9.3
and 9.4, assuming detector efficiency of 0.2-0.3, 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 -7.5 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 plutonium fraction.
15. Waste Management
15.1. Types of waste generated per sample analyzed
15.1.1. If Ca3(PC>4)2 coprecipitation is performed, 100-1000 mL of decanted solution
that is pH neutral will be generated
15.1.2. Approximately 45 mL of acidic waste from loading and rinsing the two
extraction columns will be generated. These solutions may contain an unknown
quantity of 241Am, if this radionuclide was present in the sample originally. If
the presence of 241Am is suspected, combined eluates from Steps 11.2.4.5 and
11.2.4.6 should be collected separately from other rinses, to minimize quantity
of mixed waste generated.
15.1.3. Approximately 45 mL of acidic waste from the microprecipitation method for
source preparation will be generated. The waste contains 1 mL of HF and ~ 8
mL of ethanol.
15.1.4. Unless processed further, the UTEVA cartridge may contain isotopes of
uranium, neptunium, and thorium, if any of these were present in the sample
originally.
15.1.5. TRU cartridge - ready for appropriate disposal.
15.2. Evaluate all waste streams according to disposal requirements by applicable
regulations.
16. References
16.1. ACW03 VBS, Rev. 1.6, "Americium, Plutonium, and Uranium in Water (with Vacuum
Box System)," Eichrom Technologies, Inc., Lisle, Illinois (February 2005).
16.2. G-03, V.I "Microprecipitation Source Preparation for Alpha Spectrometry", HASL-
300, 28th Edition, (February 1997).
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. VBS01, Rev.1.3, "Setup and Operation Instructions for Eichrom's Vacuum Box
System (VBS)," Eichrom Technologies, Inc., Lisle, Illinois (January 2004).
16.5. U.S. Environmental Protection Agency (EPA). 2009. Method Validation Guide for
Radiological Laboratories Participating in Incident Response Activities. Revision 0.
02/23/2010 238'239/240Pu-Pagel5 Revision 0
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
Office of Air and Radiation, Washington, DC. EPA 402-R-09-006, June. Available at:
www.epa.gov/narel/incident_guides.html.
16.6. 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 at: www.epa.gov/radiation/marlap/index.
html.
16.7. ASTM Dl 193, "Standard Specification for Reagent Water," ASTM Book of Standards
11.02, current version, ASTM International, West Conshohocken, PA.
17. Tables, Diagrams, Flow Charts, and Validation Data
17.1. Tables
Table 17.1 Alpha Particle Energies and Abundances of Importance
Nuclide
238Pu
239/240Pu(Total)[3]
239Pu
240Pu
242pu
Half-Life
(Years)
87.7
2.411xl04
2.411xl04
6.561xl03
3.735xl05
•k
(s")
2.50xl(T10
9.110xl(T13
9.110xl(T13
3.348xl(T12
5.881xl(T14
Abundance'21
0.7091
0.2898
0.9986
0.7077
0.1711
0.1194
0.7280
0.2710
0.7649
0.2348
a Energy
(MeV)
5.499
5.456
(All at same peak)
5.157
5.144
5.105
5.168
5.124
4.902
4.858
[1] Only the most abundant particle energies and abundances have been noted here.
[2] Unless individual plutonium isotopes are present, the alpha emissions for 239/240pu or separately for 238Pu, should
use an abundance factor of 1.0.
[3] Half-life and 1 are based on 239Pu.
17.2. Ingrowth Curves and Ingrowth Factors
This section intentionally left blank
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
17.3. Spectrum from a Processed Sample
Plutonium Spectrum
110 •
100 -
90 -
80 -
tn 70 •
§ 60 •
SO -
40 -
30 -
20 -
10 -
0 -
Pu-2
I
I
!
I
I
12
,
i
pij-2
JPl
19
1
r
I
\
&
u2
1
K
3023 3323 3523 3923 4223 4523
4823 5123 S423 $723 6023 6323 6623 6923 7223 7523 7823
Energy (teV)
17.4. Decay Scheme
2.46x105y
Plutonium Decay Scheme
87.7 y 2.41x104 y
7.04x108y
2.34x1 CFy
6.56x103 y
3.74x105y
4.47x109y
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
17.5. Flow chart
Analytical Flow Chart for Plutonium
Sample preparation (step 11.1)
1. Add 242Pu tracer
2. Evaporation or Ca3(PO4)2
coprecipitation(1-2 hours)
Set up of UTEVA and TRU cartridges
in tandem using vacuum box (step 11.2.2)
1. Assembly
2. Prep with 5 ml 3 M HNO3@ 1 mL/min
Preparation for cartridge (step 11.2.1)
1. Dissolve phosphate.
2. Add sulfamate, thiocyanate, ascorbic
acid (5 minutes)
Load the cartridge (step 11.2.3)
Sample: 20 ml @ 1 mL/min
Rinse: 5 ml 3 M HNO3, @ 3 mL/min
2nd rinse: 5 ml 3 M HNO3, @ 3 mL/min
(-25 minutes)
Separate cartridges (step 11.2.3.4)
UTEVA cartridge to waste
Effluent to waste
TRU cartridge for processing
Attach fresh funnel to the cartridge
Elapsed
Time
3.5 hours
Separation scheme and timeline for determination of alpha emitting Pu isotopes in water samples
Parti
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
Convert PiT3 to PiT4 (steps 11.2.4.1-4)
1. 5 ml 2 M HNO3 @ 3 mL/min
2. 5 ml 2M HN03+0.1 M NaNO2 @ 1 mL/min
3. 5 ml 0.5 M HNO3 @ 1 mL/min
Discard effluents to waste
(Step 11.2.4.7)
Caution: may contain Am
Discard TRU cartridge
(Step 11.2.4.11)
Strip Am from the cartridge (steps 11.2.4.5-6)
1.3mL9M HCI@ 1 mL/min
2. 20mL4MHCI@1 mL/min
~ 25 minutes
1
Rinse Th from the TRU cartridge (step 11.2.4.7)
25mL4MHCI-0.1 m HF
@ 3 mL/min
~ 10 minutes
Strip Pu from the TRU cartridge (step 11.2.4.8-9)
10 mL 0.1 M ammonium bioxalate
@ 1 mL/min
(10min)
Microprecipitation (step 11.3)
1. Add NdF3 carrier and wait 30 min
2. Filter, dry, mount
(1 hour)
Discard filtrates and washes
(Step 11.3.16)
Count sample test source (STS)
I for at least one hour
5.5 hours
6.5 hours
7.5 hours
Separation scheme and timeline for determination of alpha emitting Pu isotopes in water samples
Part 2
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Plutonium-238,239/240 in Water: Rapid Radiochemical Method for High-Activity Samples
Appendix
Table Al - Composition of Atlanta Drinking Water Used for this Study
Metals by ICP-AES
Silicon
Aluminum
Barium
Calcium
Iron
Magnesium
Potassium
Sodium
Inorganic Anions
Chloride
Sulfate
Nitrogen, Nitrate (as N)
Carbon Dioxide
Bicarbonate Alkalinity
Carbonate Alkalinity
Radionuclide
Uranium 234, 235, 238
Plutonium 238, 239/240
Americium 24 1
Strontium 90
Radium 226***
Concentration (mg/L)*
3.18
<0.200
0.0133
9.38
<0.100
<0.500
<0.500
<0.500
12.7
15.6
1.19
23.8
<3.00
Concentration (pCi/L)**
<0.01,<0.01,<0.01
<0.02, <0.02
<0.02
<0.3
0.11 ±0.27
-0.30 ±0.45
Note: Analyses conducted by independent laboratories.
* Values below the reporting level are presented as less than (<) values.
No measurement uncertainty was reported with values greater than the "Reporting
Level."
** Reported values represent the calculated minimum detectable concentration (MDC)
for the radionuclide(s).
*** Two samples analyzed.
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www.epa.gov
February 2010
Revision 0
Rapid Radiochemical Method for
Radiurn-226 in Water
for Environmental Restoration Following
Homeland Security Events
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
-------
-------
RADiUM-226 IN WATER:
RAPID METHOD TECHNIQUE FOR HIGH-ACTIVITY SAMPLES
1 Scope and Application
1.1. The method will be applicable to samples where contamination is either from known or
unknown origins. If any filtration of the sample is performed prior to starting the
analysis, filterable solids should be analyzed separately. The results from the analysis
of these solids should be reported separately (as a suspended activity concentration for
the water volume filtered), but identified with the filtrate results.
1.2. This method uses rapid radiochemical separations techniques for the isotopic
determination of 226Ra in water samples following a nuclear or radiological incident.
Although the method can detect 226Ra concentrations on the same order of magnitude as
methods used for the Safe Drinking Water Act (SDWA), this method is not a substitute
for SDWA-approved methods for 226Ra.
1.3. The method is specific for 226Ra and uses MnO2 fixed on a resin bed (MnO2 resin) to
separate radium from interfering radionuclides and matrix constituents with additional
separation using Diphonix® resin1 to improve selectivity by removing radioactive
impurities.
1.4. The method is capable of satisfying a required method uncertainty for 226Ra of 0.65
pCi/L at an analytical action level of 5 pCi/L. To attain the stated measurement quality
objectives (MQOs) (see Sections 9.3, 9.4, and 9.5), a sample volume of approximately
200 mL and count time of 4 hours are recommended. Application of the method must
be validated by the laboratory using the protocols provided in Method Validation Guide
for Qualifying Methods Used by Radiological Laboratories Participating in Incident
Response Activities (EPA 2009, reference 16.3). The sample turnaround time and
throughput may vary based on additional project MQOs, the time for analysis of the
final counting form and initial sample volume.
1.5. This method is intended to be used for water samples that are similar in composition to
drinking water. The rapid 226Ra method was 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 (EPA 2009,
reference 16.3) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP 2004, reference 16.4). The matrix used for the
determination of 226Ra was drinking water from Atlanta, GA. See Appendix A for a
listing of the chemical constituents of the water.
1.6. Multi-radionuclide analysis using sequential separation techniques may be possible.
2 Summary of Method
T? S
2.1. A known quantity of Ra is used as the yield determinant in this analysis. Since the
source of the suspected contamination may not be known, the sample is initially
digested using concentrated nitric acid, followed by volume reduction and conversion
to the chloride salt using concentrated hydrochloric acid. The solution is adjusted to a
1 A polyfunctional cation exchange resin containing diphosphonic and sulfonic acid functional groups bonded to a
polystyrene/divinylbenzene spherical bead. (Available commercially from Eichrom Technologies, LLC, Lisle, IL,
60561).
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neutral pH and batch equilibrated with MnC>2 resin to separate radium from some
radioactive and non-radioactive matrix constituents. Further selectivity is achieved
using a column which contains Diphonix® resin. The radium (including 226Ra) eluted
from the column is prepared for counting by microprecipitation with BaSO4.
2.2. Low-level measurements are performed by alpha spectrometry. The activity measured
in the 226Ra region of interest is corrected for chemical yield based on the observed
activity of the alpha peak at 7.07 MeV (217At, the third progeny of 225Ra). See Table
17.1 for a list of alpha particle energies of the radionuclides that potentially may be
seen in the alpha spectra.
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 decisionmaker to choose one of the alternative
actions.
3.3. Analytical Decision Level (ADL). The analytical decision level refers to the value that
is less than the AAL based on the acceptable error rate and the required method
uncertainty.
3.4. 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 (micron range).
3.5. Multi-Agency Radiological Analytical Laboratory Protocols Manual (MARL AP) (see
Reference 16.4).
3.6. Measurement Quality Objective (MQO). The analytical data requirements of the data
quality objectives that are project- or program-specific and can be quantitative or
qualitative. These analytical data requirements serve as measurement performance
criteria or objectives of the analytical process.
3.7. Radiological Dispersal Device (RDD), i.e., a "dirty bomb." This is an unconventional
weapon constructed to distribute radioactive material(s) into the environment either by
incorporating them into a conventional bomb or by using sprays, canisters, or manual
dispersal.
3.8. Required Method Uncertainty (WMR). The required method uncertainty is a target value
for the individual measurement uncertainties and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method uncertainty
as an absolute value is applicable at or below an AAL.
3.9. Relative Required Method Uncertainty (^MR). The relative required method uncertainty
is the WMR divided by the AAL and is typically expressed as a percentage. It is
applicable above the action level.
3.10. 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 in the
method, such as a solid deposited on a filter for alpha spectrometry analysis.
4 Interferences
4.1. Radiological:
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
4.1.1. All radium isotopes in addition to 226Ra are retained on MnC>2, as are thorium
isotopes. Unless other radium isotopes are present in concentrations greater than
approximately three times the 226Ra activity concentration, interference from
other radium alphas will be resolved when using alpha spectrometry. Method
performance may be compromised if samples contain high levels of radium
isotopes due to ingrowth of interfering decay progeny. Samples should be pre-
screened prior to aliquanting and appropriate limits established to control the
amount of activity potentially present in the aliquant.2
4.1.2. Decay progeny from the 225Ra tracer will continue to ingrow as more time
elapses between the separation of radium and the count of the sample. Delaying
the count significantly longer than a day may introduce a possible positive bias
in results near the detection threshold. When MQOs require measurements close
to detection levels, and coordinating sample processing and counting schedules
is not conducive to counting the sample within -36 hours of the separation of
radium, the impact of tracer progeny tailing into the 226Ra may be minimized
by reducing the activity of the 225Ra tracer that is added to the sample. This will
aid in improving the signal-to-noise ratio for the 226Ra peak by minimizing the
amount of tailing from higher energy alphas of the 225Ra progeny.
4.1.2.1. The amount of 225Ra added to the samples may be decreased, and the
time for ingrowth between separation and counting increased, to
ensure that sufficient 225Ac, 221Fr, and 217At are present for yield
corrections at the point of the count. Although this detracts from the
rapidity of the method, it does not detract from the potential for high
throughput.
4.1.2.2. The size of the sample aliquant can be increased without changing the
amount of tracer added.
4.1.3. Optimally, a purified 225Ra tracer solution3 should be used when performing this
method.
4.1.3.1. When using a purified source of 225Ra, the beginning of decay for
225Ra is the activity reference date established during standardization
of the 225Ra solution.
4.1.3.2. When a purified 225Ra tracer solution is not available, a solution
containing 225Ra in equilibrium with 229Th may be used as a tracer. In
this case, the 225Ra activity is supported only until thorium is removed
using Diphonix® resin during processing of the sample. When using
this variation of the method, the beginning of 225Ra decay is the point
when the sample has passed through the Diphonix® column.
NOTE: Recording the point in time of the beginning of 225Ra decay to within Vz
hour will introduce a maximum bias of 0.1% for this measurement.
2 For very elevated levels of radium isotopes, it is recommended that laboratories use "The Determination of
Radium-226 and Radium-228 in Drinking Water by Gamma-ray Spectrometry Using HPGE or Ge(Li) Detectors,"
Revision 1.2, December 2004. Available from the Environmental Resources Center, Georgia Institute of
Technology, 620 Cherry Street, Atlanta, GA 30332-0335, USA, Telephone: 404-894-3776.
3 Using a purified 225Ra tracer is the approach recommended for this method. See Appendix B for a method for
purification and standardization of 225Ra tracer from 229Th solution.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
4.1.4. Every effort should be made to use the purified 225Ra as a tracer. It is also
possible to use 225Ra in equilibrium with 229Th, which may be added to each
sample as a tracer.4 This approach requires complete decontamination of a
relatively high activity of 229Th by the Diphonix® column later in the method,
however, since the spectral region of interest (ROI) for 229Th slightly overlaps
that of 226Ra. Inadequate decontamination of 229Th will lead to high bias in the
226Ra result especially when the levels of 226Ra in the sample are below 1 pCi/L.
The spectral region above 226Ra corresponding to 229Th should be monitored as
a routine measure to identify samples where 229Th interference may impact
compliance with project MQOs. If problematic levels of 229Th are identified in
spectra, measures must be taken to address the interference. These might
include:
4.1.4.1. Separating 225Ra from 229Th prior to its use as a tracer. Using purified
225Ra tracer is the default approach recommended for running this
method since it will completely address any potential for interference
by removing the source of the problem.
4.1.4.2. Increasing the sample aliquant size without changing the amount of
tracer added will increase analyte signal and reduce the relative impact
of the interference to levels that may be amenable with project MQOs.
4.1.4.3. The absolute amount of 229Th added to the samples may be decreased,
as long as the time for ingrowth between separation and counting is
increased to ensure that sufficient 217At is present for yield corrections
at the point of the count. Although this detracts from the rapidity of the
method, it allows more flexibility in the timing of the count and does
not detract from the potential for high throughput.
4.1.4.4. Developing spill-down factors (peak overlap corrections) to correct for
the interference and account for additional uncertainty in the analytical
results. This is not a trivial determination and should be validated prior
to use.
4.1.5. When a solution containing 225Ra in equilibrium with 229Th is used as a tracer,
thorium is removed later in the processing of the sample. The equilibrium
between the 225Ra and 229Th is maintained only until the sample is loaded onto
the Diphonix® column. At this point, thorium and actinium are retained on the
column and the 225Ra activity in the eluate is unsupported and begins to decay.
4.2. Non-radiological:
4.2.1. Low conductivity water (<100 uS cm"1) may cause low-yield issues with some
samples. This may be partially corrected for by increasing the conductivity with
calcium standard solution.
4.2.2. Concentrations of non-radioactive barium present significantly in excess of the
amount of barium carrier added for microprecipitation may severely degrade the
resolution of alpha spectra. The quality of spectra should be monitored for
evidence of decreased resolution. A decreased sample size (i.e., smaller) may
4 The single-laboratory validation for this method was performed successfully by adding 225Ra in secular equilibrium
with 229Th tracer. Using purified 225Ra will provide better method performance since it will eliminate any concern
about breakthrough of the high levels of 229Th added to each sample. See Appendix B of this method for a method
for separating (and standardizing) 225Ra tracer from 229Th solution.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
need to be selected or the barium carrier decreased or m omitted if the presence
of these interferences leads to unacceptably degraded method performance.
4.2.3. High concentrations of non-radioactive calcium, magnesium or strontium in the
sample may not only overwhelm the ability of the MnO2 resin to effectively
exchange radium isotopes but also may degrade the alpha spectrometry peaks
and increase analytical uncertainty. A decreased sample size (i.e., smaller) may
need to be selected when the presence of these interferences leads to degraded
method performance. If it is anticipated that these elements or barium (see Step
4.2.2) are present in quantities exceeding a small fraction of the mass of calcium
or barium added in Steps 11.2.3 and 11.1.3, respectively, an analytical
determination may need to be performed separately so that the interference can
be accommodated.
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.
5.1.2. Refer to the laboratory chemical hygiene plan for general chemical safely rules.
5.2. Radiological
5.2.1. Hot Particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles" (DRPs), will
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 or finer filter
will minimize the presence of these particles.
5.2.1.2. 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 causing contamination.
5.2.1.3. Filter media should be individually surveyed for the presence of these
particles, and this information reported with the final sample results.
5.2.2. For samples with detectable activity concentrations of these radionuclides,
labware should be used only once due to the potential for cross contamination.
5.3. Procedure-Specific Non-Radiological Hazards:
5.3.1. Solutions of 30% H2O2 can rapidly oxidize organic materials and generate
significant heat. Do not mix large quantities of peroxide solution with solutions
of organic solvents as the potential for conflagration exists.
6 Equipment and supplies
6.1. Alpha spectrometer calibrated for use over the range of ~3.5-10 MeV.
6.2. Centrifuge tubes, polypropylene, 50 mL, disposable; or equivalent.
6.3. Chromatography columns, polypropylene, disposable:
6.3.1. 1.5 cm ID. x 15 cm, with funnel reservoir; or equivalent.
6.3.2. 0.8 cm ID. x 4 cm; or equivalent.
6.4. Filter stand and filter funnels.
6.5. Filter, 0.1 micron, ~25-mm diameter (suitable for microprecipitation).
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
6.6. Membrane filter, 0.45 micron, ~47-mm diameter.
6.7. Vacuum filtration apparatus.
6.8. Heat lamp, 250-300 watt, with reflectors mounted -25 cm above the base.
6.9. Petri dish or other suitable container for storing sample test sources.
6.10. Stainless steel planchets or suitable holders/backing for sample test sources - able to
accommodate a 25-mm diameter filter.
6.11. Glass beaker, 600-mL capacity.
6.12. Stirring hot plate.
6.13. Magnetic stir bar (optional).
6.14. Centrifuge bottle, polypropylene, 250 mL, disposable; or equivalent (optional).
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). For microprecipitation, all solutions used in microprecipitation should be
prepared with water filtered through a 0.45 um (or smaller) filter.
7.1. Ammonium sulfate, solid (NH/t^SO/t, available commercially.
7.2. Barium carrier (nominally 0.5 mg/mL as Ba2+). May be purchased as an atomic
absorption standard and diluted, or prepared by dissolving 0.45 g reagent grade
barium chloride, dihydrate (BaQ2-2H2O) in water and diluting to 500 mL with water.
7.3. Bromthymol blue indicator solution: Dissolve 0.1 g of bromthymol blue in 16 mL of
0.01 M NaOH. Dilute to 250 mL with water.
7.4. Calcium nitrate solution (1000 ppm as calcium). May be purchased as an atomic
absorption standard and diluted or prepared by dissolving 2.5 g of calcium carbonate
(CaCOs) in 70 mL of concentrated nitric acid and diluting to 1 L with water.
7.5. Diphonix® resin, 100-200-um mesh size [available from Eichrom Technologies,
Lisle, IL].
7.6. Ethanol, reagent 95 % (C2HsOH), available commercially.
7.7. Hydrochloric acid (12 M): Concentrated HC1, available commercially.
7.7.1. Hydrochloric acid (2M): Add 170 mL of concentrated HC1 to 800 mL of
water and dilute to 1.0 L with water.
7.7.2. Hydrochloric acid (1M): Add 83 mL of concentrated HC1 to 800 mL of water
and dilute to 1.0 L with water.
7.8. Hydrogen peroxide, H2O2 (30 % w/w), available commercially.
7.9. Isopropanol, 2-propanol, (CsHyOH), available commercially.
7.9.1. Isopropanol (2-propanol), 20 % (v/v) in water: Mix 20 mL of isopropanol
with 80 mL of water.
7.10. Methanol (CH3OH), available commercially.
7.11. MnO2 resin, 75-150 |j,m MnO2 particle size on non-functionalized polystyrene resin
beads of 100-200 mesh [available commercially from Eichrom Technologies, Lisle,
IL].
7.12. MnO2 stripping reagent: Add 2 mL of 30 % H2O2 per 100 mL of 2 M HC1. Prepare
fresh for each use.
7.13. Nitric acid (16 M): Concentrated HNOs, available commercially.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
7.14. Sodium hydroxide (1 M): Dissolve 4 g of sodium hydroxide (NaOH) in 50 mL of
water and dilute the solution to 100 mL.
7.15. Ra-225 tracer in 1-M HC1 solution in a concentration amenable to accurate addition
of about 180 dpm per sample (generally about 150-600 dpm/mL).
7.15.1. Ra-225 may be purified and standardized using a 229Th / 225Ra generator as
described in Appendix B of this method.
7.15.2. Th-229 containing an equilibrium concentration of 225Ra has been
T? S
successfully used without prior separation of the Ra. However, this
approach may be problematic due to the risk of high result bias (see
discussion in Steps 4.1.4 - 4.1.5).
8 Sample Collection, Preservation and Storage
8.1. Samples should be collected in 1-L plastic containers.
8.2. No sample preservation is required if sample analysis is initiated within 3 days of
sampling date/time.
8.3. If the sample is to be held for more than three days, HNO3 shall be added until the
solution pH is less than 2.0.
8.4. If the dissolved concentration of radium 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
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 manual
and procedures shall be used to determine acceptable performance for this method.
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 a 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 may be included as a batch quality control sample if
there is concern that matrix interferences, such as the presence of elemental
barium in the sample, may compromise chemical yield measurements, or
overall data quality.
9.2. Sample-specific quality control measures
9.2.1. Limits and evaluation criteria shall be established to monitor each alpha
spectrum to ensure that spectral resolution and peak separation is adequate
to provide quantitative results. When 229Th / 225Ra solution is added directly
to the sample, the presence of detectable counts between -5.0 MeV and the
T7£\
upper boundary established for the Ra ROI generally indicates the
T7Q 00^
presence of Th in the sample, and in the Ra ROI. If the presence of
229Th is noted and the concentration of 226Ra is determined to be an order of
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
magnitude below the action limit or the detection threshold of the method,
take corrective actions to ensure that MQOs have not been compromised
(e.g., clean-up 225Ra tracer before adding, or re-process affected samples and
associated QC samples. See interferences sections Steps 4.1.4 - 4.1.5. for
discussion).
9.3. This method is capable of achieving a MMR of 0.65 pCi/L at or below an action level of
5.0 pCi/L. This may be adjusted in the event specific MQOs are different.
9.4. This method is capable of achieving a ^MR 13% above 5 pCi/L. This may be adjusted
if the event specific MQOs are different.
9.5. This method is capable of achieving a required minimum detectable concentration
(MDC)of l.OpCi/L.
10 Calibration and Standardization
10.1. Set up, operate, calibrate and perform quality control for alpha spectrometry units in
accordance with the laboratory's quality manual and standard operating procedures
and consistent with ASTM Standard Practice D7282, Sections 7-13, 18, and 24 (see
reference 16.5).
Note: The calibrated energy range for the alpha spectrometer for this method should be from
-3.5 to 10 MeV
10.2. If 225Ra is separated and purified from 229Th for use as a tracer, the activity reference
date established during standardization of the tracer is used as the 225Ra activity
reference date (see Appendix B of this method).
10.3. When using 229Th containing an equilibrium concentration of 225Ra, the time of most
recent separation / purification of the 229Th standard solution must be known in order
to determine the extent of secular equilibrium between 229Th and its 225Ra progeny.
Verify the date of purification by examining the Certificate of Analysis, or other
applicable documentation, for the standard.
10.4. When using 229Th containing an equilibrium concentration of 225Ra, 225Ra is separated
from its 229Th parent as the solution passes through the Diphonix column. This is the
beginning of 225Ra decay and the date and time used for decay correction of the
tracer.
10.4.1. If the purification date of the 229Th is not documented, at least 100 days must
OOQ
have elapsed between separation and use to ensure that Th, and its
progeny 225Ra are in full secular equilibrium (i.e., >99%. See Table 17.3).
11 Procedure
11.1. Initial Sample Treatment
11.1.1. For each sample in the batch, aliquant 0.2 L of raw or filtered water into a
beaker.
Note: Smaller or larger aliquants may be used if elevated sample activity is present or
as needed to meet detection requirements or MQOs. Method validation must be
conducted using approximately the same volume as that to be used in sample analysis^
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
11.1.2. To each aliquant, add 10 mL of concentrated nitric acid per 100 mL of
sample.
11.1.3. To each sample aliquant, add 100 uL of 0.5 mg/mL (nominal) barium carrier
solution and approximately 180 dpm of 225Ra tracer solution. The initial
amount of 225Ra added as a tracer should be high enough so that the
resultant counting uncertainty of the 217At activity ingrown from the tracer is
five percent (5 %) or less during the allotted sample count time.
Note: The activity of 217At present at the midpoint of the count is used to calculate the
chemical yield for radium by back-calculating the activity of 225Ra recovered. The
initial amount of 225Ra added as tracer may need to be varied to accommodate
planned differences in the time that will elapsed between chemical separation and the
count, but the activity should be sufficient, and the count time long enough, to ensure
that the resultant counting uncertainty for the 217At peak is five (5 %) percent or less.
See the calculation for At, in Step 12.2 for calculation of ingrowth factor for 217At and
Table 17.2 for typical ingrowth factors for a series of ingrowth times.
11.1.4. Reduce the sample volume to -20% of the original volume by bringing the
solution to a gentle boil and evaporating.
11.1.5. Following this digestion, add 10 mL of concentrated hydrochloric acid, and
carefully evaporate the solution to incipient dryness.
11.1.6. Reconstitute the sample by adding 100 mL of 1-M HC1. The sample may be
gently heated if necessary to facilitate dissolution of residual salts.
11.2. Water Sample Preparation and Pre-concentration of Radium on MnO2 resin:
11.2.1. Add 100 mL of 1-MNaOHto each sample.
11.2.2. If particulate material is visible at this time, filter the sample through a 0.45-
|im filter. (Do not rinse the filter). The filter should be saved for possible
analysis for DRPs.
11.2.3. Add enough 1000 ppm calcium solution to the filtrate from Step 11.2.2 to
ensure that the final calcium concentration is about 10 ppm. For waters that
naturally have calcium in them above 10 ppm this step will be unnecessary.
11.2.4. Add a few drops of bromthymol blue indicator solution and adjust each
sample to neutral pH by carefully adding 1-M NaOH until the color changes
from yellow to blue-green.
Note: Adding too much base will overshoot the blue-green endpoint (indicated by blue
color). The amount of NaOH added in Step 11.2.4 may be adjusted by carefully
adding a small quantity of 1-M HC1 and 1-M NaOH as needed to reach a blue-green
endpoint.
11.2.5. The sample is equilibrated with -1.0 g MnO2 resin for 0.5-1.5 hours. Two
options are provided:
11.2.5.1. Option 1: Add -1.0 g MnO2 resin to a beaker containing the
neutralized sample. Cover with a watch glass and stir on a
magnetic stirrer for at least 30 minutes.
11.2.5.2. Option 2: Transfer the neutralized sample to a 250 mL centrifuge
bottle which contains -1.0 g MnO2 resin. Agitate the bottle gently
on a shaker or in a tumbler for at least 30 minutes.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
Note: Two options are provided for contacting the sample with MnO2 resin.
The contact time noted above (30 minutes) is to be understood as a
minimum. Higher radium yields may be obtained with somewhat longer
contact times (up to 90 minutes). Excessive agitation of the resin may lead
to abrasion and loss of some MnO2 from the resin and result in degraded
chemical yields. Although sample quantitation is not significantly impacted
since a 225Ra yield tracer is used, uptake on the resin during this step should
be reasonably optimized by evaluating the process and time used and
choosing a default optimal conditions corresponding to a minimum of 80-
85% uptake from a clean water matrix.
11.2.6. Pour the suspension into a 1.5-cm ID. x 15-cm column fitted with a
reservoir funnel. Allow sample to pass through column. Rinse the walls of
the funnel reservoir and column with demineralized water. The combined
column effluent from this step may be discarded.
11.2.7. Place a clean 50 mL centrifuge tube under each MnC>2 column. Add 10 mL
of freshly made MnC>2 Stripping Reagent to the MnC>2 column to elute
radium and other elements. Catch the column eluate containing radium and
retain for subsequent processing.
Note: Effervescence will be noted upon addition of the MnO2 Stripping Reagent.
Gently tapping the column to dislodge any bubbles that form will help minimize
channeling and may improve radium recovery. The resin bed will become light yellow
in color as MnO2 dissolves.
11.3. Actinium and Thorium Removal Using Diphonix® resin:
11.3.1. Prepare a Diphonix® resin column for each sample to be processed as
follows:5
11.3.1.1. Slurry -1.0 gram Diphonix® resin per column in water.
11.3.1.2. Transfer the resin to the 0.8-cm ID. x 4-cm columns to obtain a
uniform resin bed of-1.4-1.6 mL (bed height -26-30 mm). A top
column barrier (e.g., frit, glass wool, beads) may be used to
minimize turbulence that may disrupt the resin bed when adding
solution to the column.
11.3.2. Precondition the column by passing 20 mL of 2-M HC1 through the column
discarding the column effluent.
11.3.3. Place a clean 50-mL centrifuge tube under each Diphonix® column.
11.3.4. Swirl the solution retained in Step 11.2.7 to remove bubbles and carefully
load onto the column taking care to minimize disturbing the resin bed.
Collect column effluents in the 50-mL centrifuge tube. Allow the solution to
flow by gravity.
11.3.5. When the load solution has stopped flowing (or is below the top of the resin
bed), rinse the column with two 5-mL volumes of 2-M HC1. Collect the
rinse solutions in the same 50-mL centrifuge tube (the total volume will be
approximately 20 mL).
5 Commercially supplied pre-packed columns may be used here. When packing columns using bulk resin, excessive
resin fines should be removed by rinsing the resin one or more times with an excess of water and decanting the
water containing the fines prior to transferring the material to the column.
226
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
11.3.6. Record the date and time of the last rinse (Step 11.3.5) as the date and time
of separation of radium from parent and progeny. This is also the beginning
of ingrowth of 225Ac (and 221Fr and 217At).
Note: If purified 225Ra tracer is added to the sample (see Step 10.2 and Appendix B),
the 225Ra activity was unsupported before the tracer solution was added to the sample.
The activity reference date and time established during standardization of the 225Ra
tracer is used as the reference date for the 225Ra solution.
Note: If 225Ra at some degree of secular equilibrium with 229Th is added as tracer in
the initial step, the activity of 225Ra is dependent upon the total amount of time
between the last 229Th purification and Stepll.3.6. The decay of 225Ra starts at Step
11.3.6.
®
Note: The Diphonix resin contains thorium, actinium and possibly other
radionuclides present in the sample and should be disposed of according to applicable
laboratory procedures.
11.4. Barium sulfate micro-precipitation of 226Ra
11.4.1. Add ~3.0 g of (NH4)2SO4 to the 20 mL of 2M HC1 solution collected from
the Diphonix® column in Steps 11.3.3 - 11.3.5. Mix gently to completely
dissolve the salt (dissolves readily).
11.4.2. Add 5.0 mL of isopropanol and mix gently (to avoid generating bubbles).
11.4.3. Place in an ultrasonic bath filled with cold tap water (ice may be added) for
at least 20 minutes.
11.4.4. Pre-wet a 0.1-micron filter using methanol or ethanol. Filter the suspension
through the filter using vacuum. The precipitate will not be visually
apparent.
11.4.5. Rinse the sample container and filter apparatus with three 2-mL portions of
20% isopropanol solution to dissolve residual (NH4)2SO4. Allow each rinse
to completely pass through filter before adding the subsequent rinse.
11.4.6. Rinse the filter apparatus with about 2 mL of methanol or ethanol to
facilitate drying. Turn off vacuum.
11.4.7. Carefully remove the filter and place it face-side up in a Petri dish. Carefully
dry under a heating lamp for few minutes. Avoid excessive heat which may
cause the filter to curl or shrink.
11.4.8. Mount the dried filter on a support appropriate for the counting system to be
used.
11.4.9. Store the filter for at least 24 hours to allow sufficient 217At (third progeny
of 225Ra) to ingrow into the sample test source allowing a measurement
uncertainty for the 217At of < ~5 %.
11.4.10. Count by alpha spectrometry. The count times should be adjusted to meet
the uncertainties and detection capabilities identified in Steps 9.3, 9.4, and
9.5.
12 Data Analysis and Calculations
12.1. The final sample test source (filter mounted on a planchet) will need to have at least a
24-hour ingrowth for 225Ac (and 221Fr and 217At) to meet Analytical Protocol
Specifications for chemical yield with a counting time of 4 hours. At-217 (third
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
progeny of 225Ra) has a single, distinct alpha peak with a centroid at 7.067 MeV and
is used for determining the yield.
Note: Actinium 225 and other decay progeny from the 225Ra (e.g., 217At) tracer will continue to
ingrow as time elapses between separation and the count of the sample. Delaying the count
significantly longer than a day may introduce a possible positive bias in results near the detection
threshold. When sample counting will be delayed longer than 36 hours, and MQOs foresee
decisions being made close to detection levels, the impact of tracer progeny tailing should be
minimized. Possible approaches for accomplishing this may include improving the signal to noise
ratio by: 1) Processing a larger sample aliquant; 2) Decreasing the tracer activity added to a level
that will still provide adequate statistics ~400-1500 net counts at the time of the analysis but will
minimize spilldown into the 226Ra ROI.
12.2. While the radiochemical yield is not directly used to determine the 226Ra activity of
the sample, the following equation can be used to calculate the radiochemical yield
(see Reference 16.6), if required:
RY =
s x At x It
Where:
RY = Fractional radiochemical yield based on 225Ra (from ingrown 217At
at 7.07 MeV)
Rt = Total count rate beneath the 217At peak at 7.07 MeV, cpm
R\, = Background count rate for the same region, cpm
e = Efficiency for the alpha spectrometer
Note: If 225Ra is separated from 229Th for use as a purified tracer, the 225Ra activity is
unsupported and begins to decay at the point of separation from 229Th, and not in Stepll.3.6.
Instead, the reference date and time established when the tracer is standardized is used for decay
correction of the 225Ra activity. If 229Th solution (with 225Ra in full secular equilibrium) is added
to the sample, the 225Ra activity is equal to the 229Th activity added and only begins to decay at
the point of separation of 225Ra from 229Th in Step 11.3.6.
At = The activity of 217At at midpoint of the count (the target value that
should be achieved for 100% yield), in dpm.
= 3.0408 (/tK5
A22SRa = Activity in dpm of 225Ra tracer added to the sample in Step 11.1.3
decay corrected to the date and time of radium separation in
Stepll.3.6.6
6 When separated 225Ra tracer is added to the sample, its initial activity, yl225Ra-imtiai, must be corrected for decay from
the reference date established during standardization of the tracer to the point of separation of 225Ra and 225Ac as
follows:
Ra \ Ra-initial
where: h\ = decay constant for 225Ra (0.04652 d~:); and dt = time elapsed between the activity reference date for the
225Ra tracer solution added to the sample and the separation of 225Ra and 225Ac in Step 11.3.6 (days).
When 229Th containing ingrown 225Ra is added directly to the sample, the amount of 225Ra ingrown since purification
of the 229Th solution is calculated as:
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d = Elapsed ingrowth time for 225Ac [and the progeny 217At], in days
from the date and time of Ra separation to the midpoint of the
sample count
AI = 0.04652 d'1 (decay constant for 225Ra - half-life = 14.9 days)
A2 = 0.06931 d'1 (decay constant for 225Ac) - half-life = 10.0 days)
/t = Fractional abundance for the 7.07 MeV alpha peak counted (=
0.9999)
3.0408 = A2 /\A2 A^} [a good approximation as the half lives of 221Fr and
217At are short enough so that secular equilibrium with 225Ac is
ensured]
12.3. The activity concentration of an analyte and its combined standard uncertainty are
calculated using the following equations:
AC=.
VaxRnixDaxIax2.22
«.HC.) = )x , , ,
^ "• *"* 2 2 2 L
where:
ACa = activity concentration of the analyte at time of count, (pCi/L)
At = the theoretical activity of 217At at midpoint of the count that should
be achieved for 100% yield, in dpm (see Step 12.2 for detailed
calculation)
Rna = net count rate of the analyte in the defined region of interest (ROI),
in counts per minute (Note that the peaks at 4. 784 and 4. 602 MeV
are generally included in the ROI for 226Ra)
Rnt = net count rate of the tracer in the defined ROI, in counts per minute
Fa = volume of the sample aliquant (L)
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, if required
/a = probability of a emission for 226Ra (The combined peaks at 4. 78
and 4. 602 Me V are generally included in the ROI with an
abundance of LOO.}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 (dpm)
where: ^4229Th = Activity of the 229Th standard on the date of the separation of Th and Ra (Step 11.3.6); ^ = decay
constant for 225Ra (0.04652 d"1); and dl = time elapsed between the purification of 229Th solution added to the sample
and the separation of 225Ra and 229Th/225Ac in Step 1 1.3.6 (days).
7 If the individual peak at 4.78 MeV used, and completely resolved from the 4. 602 MeV peak, the abundance would
be 0.9445.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
z/(Fa) = standard uncertainty of the volume of sample aliquant (L)
u(Rna) = standard uncertainty of the net count rate of the analyte in counts
per minute
u(Rni) = standard uncertainty of the net count rate of the tracer in counts per
minute
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 (uc(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 that
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.
12.3.1 The net count rate of an analyte or tracer and its standard uncertainty can be
calculated using the following equations:
Rnx = net count rate of analyte or tracer, in counts per minute8
Cx = sample counts in the analyte or the tracer ROI
4 = sample count time (min)
Cbx = background counts in the same ROI as for x (x refers to the
respective analyte or tracer count)
tb = background count time (min)
u(Rnx) = standard uncertainty of the net count rate of tracer or
analyte, in counts per minute
12.3.2 If the critical level concentration (Sc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations.9
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.
9 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. The formulations presented here assume an error rate of a = 0.05, ft = 0.05 (with Z!_a = zi-p = 1.645),
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0.4 x M- -1 + 0.677 x 1 + -M +1.645 x
,'-
S=-
4 x Dt x It
tsxVaxRtxDax!a
MDC =
2.71x 1 + - +3.29x Rt
b
bas
A
where:
Rbn = background count rate for the analyte in the defined ROI, in counts
per minute
12.4 Results Reporting
12.4.1 The following data should be reported for each result: volume of sample
used; yield of tracer and its uncertainty; and full width at half maximum
(FWHM) of each peak used in the analysis.
12.4.2 The following conventions should be used for each result:
12.4.2.1 Result in scientific notation ± combined standard uncertainty.
12.4.2.2 If solid material was filtered from the solution and analyzed
separately, the results of that analysis should be reported separately
as pCi/L of the original volume from which the solids were filtered
if no other guidance is provided on reporting of results for the
solids. For example:
226Ra for Sample 12-1-99:
Filtrate Result: 12.8 ± 1.5 pCi/L
Filtered Residue Result: 2.5 ± 0.3 pCi/L
13 Method Performance
13.1 Results of method validation performance are to be archived and available for
reporting purposes.
13.2 Expected turnaround time for an individual sample is -35 hours and per batch is -38
hours.
14 Pollution Prevention
14.1 The use of MnO2 and Diphonix® resin reduces the amount of solvents that would
otherwise be needed to co-precipitate and purify the final sample test source.
15 Waste Management
15.1 Nitric acid and hydrochloric acid wastes should be neutralized before disposal and
then disposed of in accordance with local ordinances.
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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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
15.2 All final precipitated materials contain tracer and should be dealt with as radioactive
waste and disposed of in accordance with the restrictions provided in the facility's
NRC license.
16 References
16.1 RAW04-10, "Radium-226/228 in Water (MnO2 Resin and DGA Resin Method),"
Eichrom Technologies, Lisle Illinois (June 2006).
16.2 A Rapid Method For Alpha-Spectrometric Analysis of Radium Isotopes in Natural
Waters Using Ion-Selective Membrane Technology; S. Purkl and A. Eisenhauer.
Applied Radiation and Isotopes 59(4):245-54 (Oct 2003).
16.3 U.S. Environmental Protection Agency (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. Available
at: www.epa.gov/narel/incident guides.html.
16.4 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 at: www.epa.gov/radiation/
marlap/index.html.
16.5 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.
16.6 S. Purkl and A. Eisenhauer (2003). "A Rapid Method for Alpha-Spectrometric
Analysis of Radium Isotopes in Natural Waters Using Ion-Selective Membrane
Technology." Applied Radiation and Isotopes 59(4):245-54.
226
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
17 Tables, Diagrams, and Flow Charts
17.1 Tables [including major radiation emissions from all radionuclides separated]
Table 17.1 Alpha Particle Energies and Abundances of Importance
Energy
(MeV)
4.601
4.784
4.798
4.815
4.838
4.845
4.901
4.968
4.979
5.053
5.434
5.449
5.489
5.540
5.580
5.607
5.609
5.637
5.682
5.685
5.716
5.724
5.732
5.732
5.747
Abundance
(%)
5.6
94.5
1.5
9.3
5.0
56.2
10.2
6.0
3.2
6.6
2.2
5.1
99.9
9.0
1.2
25.2
1.1
4.4
1.3
94.9
51.6
3.1
8.0
1.3
9.0
Nuclide
Ra -226
Ra -226
Th-229
Th-229
Th-229
Th-229
Th-229
Th-229
Th-229
Th-229
Ra-223
Ra-224
Rn-222
Ra-223
Ac -225
Ra -223
Ac -225
Ac -225
Ac -225
Ra -224
Ra -223
Ac -225
Ac -225
Ac -225
Ra -223
- Analyte
Energy
(MeV)
5.791
5.793
5.830
5.869
6.002
6.051
6.090
6.126
6.243
6.278
6.288
6.341
6.425
6.553
6.623
6.778
6.819
7.386
7.450
7.687
8.376
8.525
11.660
Abundance
(%)
8.6
18.1
50.7
1.9
100.0
25.1
9.8
15.1
1.3
16.2
99.9
83.4
7.5
12.9
83.5
100.0
79.4
100.0
98.9
100.0
100.0
2.1
96.8
Nuclide
Ac -225
Ac -225
Ac -225
Bi-213
Po -218
Bi-212
Bi-212
Fr-221
Fr-221
Bi-211
Rn-220
Fr-221
Rn-219
Rn-219
Bi-211
Po-216
Rn-219
Po-215
Po-211
Po-214
Po-213
Po-212
Po-212
217
At (3rd progeny of Ra tracer)
[ | - 229Th (Check ROI for indications of inadequate clean-up)
Includes only alpha particles with abundance > 1%.
Reference: NUDAT 2.4, Radiation Decay National Nuclear Data Center, Brookhaven National
Laboratory; Available at: www.nndc.bnl.sov/nudat2/indx dec.jsp; Queried: November 11, 2007.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
17.2 Ingrowth curves and Ingrowth factors
1000
0.1
Ac-225 In-Growth in Ra-225
200
400 600
Time, Hours
800 1000
Ra-225 In-Growth in Th-229
20 40
60
Days
-Th-229, dpm
- Ra-225, dpm
80 100 120
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
Table 17.2. Ingrowth Factors for 217At in 225Ra
Time elapsed between
separation of Ra and
midpoint of count
in hours
Ingrowth Factor*
Time elapsed between
separation of Ra and
midpoint of count
in hours
Ingrowth Factor*
1
0.002881
72
0.1748
2
0.005748
96
0.2200
3
0.008602
120
0..2596
4
0.01144
144
0.2940
5
0.01427
192
0.3494
6
0.01708
240
0..3893
24
0.06542
360
0.4383
48
0.1235
480
0.4391
'ingrowth Factor represents the fraction of217Ac activity at the midpoint of the sample count relative to the 225Ra
activity present at the date/time ofRa separation. These ingrowth factors may be closely approximated (within a
fraction of a percent) using the expression for At in Step 12.2.2.
Table 17.3 Ingrowth Factors for 225Ra in 229Th
Time elapsed between
purification of the 229Th
standard and date of Ra
separation
in days
Ingrowth Factor*
Time elapsed between
purification of the 229Th
standard and date of Ra
separation
in days
Ingrowth Factor*
1
0.04545
50
0.9023
5
0.2075
55
0.9226
10
0.3720
60
0.9387
12
0.4278
70
0.9615
15
0.5023
80
0.9758
20
0.6056
90
0.9848
25
0.6875
100
0.9905
27
0.7152
130
0.9976
30
0.7523
160
0.9994
40
0.8445
200
0.9999
Ingrowth Factor represents the fraction Ra activity/ Th activity at the time ofRa separation.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
225T
Table 17.4 Decay Factors for Unsupported Ra
Time elapsed
between separation
of229Thand225Ra
in days
Decay Factor*
Time elapsed
between separation
of229Thand225Ra
in days
Decay Factor*
1
0.9545
50
0.09769
5
0.7925
55
0.07741
10
0.6280
60
0.06135
12
0.5722
70
0.03853
15
0.4977
80
0.02420
20
0.3944
90
0.01519
25
0.3125
100
0.00954
27
0.2848
130
0.00236
30
0.2477
160
0.00059
40
0.1555
200
0.00009
Decay Factor represents the fraction Ra activity remaining.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
17.3 Example Alpha Spectrum from a Processed Sample
100^
80
3
o
O
5000
216Po6/219Rnn
•background
•1
5 Th-series
s Np-series
: U-Ra-series
Ac-series
6000
7000
8000
9000
Energy/keV
Reference: Purkl, Stefan, Dissertation: Entwicklung und Anwendung neuer analytischer Methoden zur
schnellen Bestimmung von kurzlebigen Radiumisotopen und Radon im Grundwasserbeeinflussten Milieu der
Ostsee; Chapter 2, Figure 3; Christian-Albrechts Universitaet, Kiel, Germany, 2003.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
17.4 Decay Schemes for Analyte and Tracer
a
164 MS
22.2 y
P
226Ra Decay Scheme
Secular equilibrium is
established between 22BRa
and 222Rn in about 18 days.
1 h
3.1 min
Q
27 min
P
1,600y
a
3.8 d
a
It takes about 4 hours for secular
equilibrium to be established
between 222Rn and 214Po after
fresh 222Rn is separated.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
17.5 Flowchart
Note: Shaded figures are associated with the timeline.
11.1.1 to 11.1.5
Aliquant sample.
Add nitric acid,
tracer and barium
carrier and digest.
Separation Scheme and Timeline for 226Ra
11.3.1 to 11.3.2
Prepare and pre-
condition Diphonix
column.
11.1.6
Reduce volume and
reconstitute with
with 100mL
of 1MHCL.
11.2.5.1 or 11.2.5.2
Equilibrate sample
with Mn02 resin for
30-90 min.
11.2.1 to 11.2.4
Add NaOH and filter
to remove parti culates.
Add calcium nitrate.
Add indicator and adjust
pHto neutral.
11.2.6
Transfer Mn02
resin to a column.
Rinse with
demineralized water.
Discard eluent.
11.3.3 to 11.3.4
Load solution fromtvln02 onto
Diphonix column and
allow to gravity drain.
Elute with two more 5-mL
all quants of 2M HCI.
11.2.7
Add 10 ml
2M HCI/0.6% H202
to strip Mn02 resin into
centrifuge tube.
11.3.5
Collect, load, and rinse
eluates containing
radium.
11.4.1 to 11.4.6
Add ammonium sulfate,
isopropanol, and
ultrasonicate
topptRa/BaS04.
1 2.5
4 6
Timeline (Hours)
7.
30
34
37
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
Appendix A:
Composition of Atlanta Drinking Water Used for this Study
Metals by ICP-AES
Silicon
Aluminum
Barium
Calcium
Iron
Magnesium
Potassium
Sodium
Inorganic Anions
Chloride
Sulfate
Nitrogen, Nitrate (as N)
Carbon Dioxide
Bicarbonate Alkalinity
Carbonate Alkalinity
Radionuclide
Uranium 234, 235, 238
Plutonium 238, 239/240
Americium 24 1
Strontium 90
Radium 226***
Concentration (mg/L)*
3.18
<0.200
0.0133
9.38
<0.100
<0.500
<0.500
<0.500
12.7
15.6
1.19
23.8
<3.00
Concentration (pCi/L)**
<0.01,<0.01,<0.01
<0.02, <0.02
<0.02
<0.3
0.11 ±0.27
-0.30 ±0.45
Note: Analyses conducted by independent laboratories.
* Values below the reporting level are presented as less than (<) values.
No measurement uncertainty was reported with values greater than the "Reporting
Level."
** Reported values represent the calculated minimum detectable concentration (MDC)
for the radionuclide(s).
*** Two samples analyzed. Expanded uncertainty (k=2) as reported by the laboratory.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
Appendix B:
Preparation and Standardization of 225Ra Tracer Following Separation from 229Th
Bl. Summary Description of Procedure
This procedure describes a 225Ra generator to make tracer amounts of 225Ra using a 229Th
solution. Th-229 is separated from 225Ra using Y(OH)3 co-precipitation. Th-229 is carried in the
precipitate and most of the 225Ra remains in solution. Centrifugation to remove 229Th in the
precipitate and filtration of the supernate produces the 225Ra tracer solution. The 225Ra activity of
the tracer solution is standardized by counting sample test sources prepared from at least five
replicate aliquants of the 225Ra solution, each spiked with a known quantity of a 226Ra standard.
This standardized activity concentration, referenced to the date and time of the 225Ra separation
described in Step4.11.7 below, is then decay-corrected to the date and time of subsequent sample
analyses.
The Y[Th](OH)3 precipitate may be stored and re-used later to generate more 225Ra tracer
T)S OOQ
solution. Ra ingrows in the Th fraction (Y(OH)3 precipitate) and after 50 days will be about
90% ingrown. After sufficient ingrowth time 225Ra may be harvested to make a fresh 225Ra tracer
solution by dissolving the precipitate and re-precipitating Y(OH)3to separate 229Th from 225Ra.
Multiple 225Ra generators may be prepared to ensure that 225Ra tracer will be continuously
available. The 225Ra tracer solution produced is usable for 2-3 half-lives (-30-45 days). To
minimize effort involved with standardization of the 225Ra solution, it is recommended that the
laboratory staff prepare an amount of 229Th sufficient to support the laboratory's expected
workload for 3-5 weeks. Since the 229Th solution is reused, and the half-life of 229Th is long
(7,342 years), the need to purchase a new certified 229Th solution is kept to a minimum.
B2. Equipment and Supplies
B2.1. Refer to Section 6 of the main procedure.
B3.Reagents and Standards
B3.1. Refer to Section 7 of the main procedure.
B4. Procedure
B4.1. Add a sufficient amount of 229Th solution (that which will yield at least 150-600
dpm/mL of the 225Ra solution) to a 50-mL centrifuge tube.15
B4.2. Add 20 mg Y (2 mL of 10 mg/mL Y metals standard stock solution).
B4.3. Add 1 mg Ba (0.1 mL of 10 mg/mL Ba metals standard stock solution).
B4.4. Add 4 mL of concentrated ammonium hydroxide to form Y(OH)3 precipitate.
B4.5. Centrifuge and decant the supernatant into the open barrel of a 50-mL syringe, fitted
with a 0.45-|im syringe filter. Hold the syringe barrel over a new 50-mL centrifuge
tube while decanting. Insert the syringe plunger and filter the supernatant into the new
centrifuge tube. Discard the filter as potentially contaminated rad waste.
15 For example, if 40 mL of a 229Th solution of 600 dpm/mL is used, the maximum final activity of 225Ra will be
~510 dpm/mL at Step B4.8. This solution would require about 1.4 mL for the standardization process and about 8
mL for a batch of 20 samples.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
B4.6. Cap the centrifuge tube with the precipitate, label clearly with the standard ID,
precipitation date, and the technician's initials and store for future use.
B4.7. Properly label the new centrifuge tube with the supernate. This is the 225Ra tracer
solution.
B4.8. Add 3 mL of concentrated HC1 to 225Ra tracer solution. Cap centrifuge tube and mix
well.
B4.9. Prepare the following solutions in 10 mL of 2-M HC1 for standardization of 225Ra
tracer.
Solution Spike(s)
Standardization -80 dpm of the 225Ra tracer solution, and
Replicates ~8 dpm of a 226Ra standard traceable to NIST or
(5 replicates) equivalent
Blank -80 dpm of the 225Ra tracer solution (the blank
should be evaluated to confirm that 226Ra is not
detected in the 225Ra tracer solution at levels that
may compromise sample results when used in the
method)
Standardization -80 dpm of the 225Ra tracer solution, and
Control Sample -8 dpm of a second source independent traceable
226Ra standard (the Standardization Control Sample
should be evaluated to confirm that the standardiza-
tion process does not introduce significant bias into
the standardized value for the 225Ra tracer)
B4.10. Add 75 |ig Ba (0.075 mL of 1000 |ig/mL Ba) to all solutions.
B4.11. Process the solutions to prepare sources for alpha spectrometry as follows:
B4.11.1. Slurry -1.0 g of Diphonix® resin per column in water.
B4.11.2. Transfer the resin to 0.8 cm (ID.) x 4 cm columns to obtain a uniform
resin bed.
B4.11.3. Precondition the columns by passing 20 mL 2 M HC1 through the
columns. Discard the effluent.
B4.11.4. Place clean 50-mL centrifuge tubes under the columns.
B4.11.5. Load the solutions from Step B4.10 onto the columns. Collect the
effluents in the 50-mL centrifuge tubes. Allow the solutions to flow by
gravity.
B4.11.6. When the load solutions have stopped flowing, rinse columns with two 5-
mL volumes of 2-M HC1. Collect the rinse solutions in the same 50-mL
centrifuge tubes (the total volume will be about 20 mL).
B4.11.7. Record the date and time of the last rinse as the date and time of
separation of radium (beginning of 225Ac ingrowth).
B4.11.8. Add -3.0 grams of (NH4)2SO4 to the solutions from Step B4.11.6. Mix
gently to dissolve.
B4.11.9. Add 5.0 mL of isopropanol and mix gently.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
B4.11.10. Place in an ultrasonic bath filled with cold tap water for at least 20
minutes.
B4.11.11. Filter the suspensions through pre-wetted (using methanol or ethanol) 0.1-
um filters.
B4.11.12. Rinse the filters with three 2-mL portions of 20% isopropanol. Allow each
rinse to completely pass through filter before adding the next rinse.
B4.ll.13. Rinse each filter with about 2 mL of methanol or ethanol.
B4.11.14. Carefully place each filter face-side up on a labeled stainless steel
planchet, or other suitable source mount, which has previously been
prepared with an appropriate adhesive (e.g., double stick tape).
B4.11.15. Dry under a heat lamp for a few minutes.
B4.11.16. After allowing about 24-hours ingrowth, count the standardization sources
by alpha spectrometry.
B4.12. Calculate the activity of 225Ra, in units of dpm/mL, in the standardization replicates,
at the 225Ra time of separation as follows:
where:
Amn = Activity concentration of 225Ra, in dpm/mL [at the time of separation from
229Th, Step B4.11.7]
= Total counts beneath the 217At peak at 7.07 MeV
= Total counts beneath the 226Ra peak at 4.78 MeV
Nb = Background count rate for the corresponding region of interest,
4 = Duration of the count for the sample test source, minutes
tb = Duration of the background count, minutes
A = Activity of 226Ra added to each aliquant, in dpm/mL
226Ra
F22g = volume of 226Ra solution taken for the analysis (mL)
V = volume of 225Ra solution taken for the analysis (mL)
225Ra
d = Elapsed ingrowth time for 225Ac [and the progeny 217At], from separation to
the midpoint of the sample count, days
Ai = 0.04652 d"1 (decay constant for 225Ra - half-life = 14.9 days)
A2 = 0.06931 d'1 (decay constant for 225Ac) - half-life = 10.0 days)
/t = Fractional abundance for the 7.07 MeV alpha peak counted (= 0.9999)
3.0408 = X2dj(X2d - \d) [a good approximation as the half lives of 221Fr and 217At are
short enough so secular equilibrium with 225Ac is ensured]
Note: The activity of the separated A22SRa will need to be decay corrected to the point of separation in the
main procedure (Step 11.3.6) so that the results can be accurately determined.
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Radium-226 in Water: Rapid Radiochemical Method for High-Activity Samples
225T
B4.13. Calculate the uncertainty of the activity concentration of the Ra tracer at the
reference date/time:
3.0408x/!17 x \e-^d-e-^d)\ xV2,
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www.epa.gov
February 2010
Revision 0
Rapid Radiochemical Method for
Total Radiostrontium (Sr-90) In Water
for Environmental Restoration Following
Homeland Security Events
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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TOTAL RADIOSTRONTIUM (SR-90) IN WATER:
RAPID METHOD FOR HIGH-ACTIVITY SAMPLES
1. Scope and Application
1.1. The method will be applicable to samples where the source of the contamination is
either from known or unknown origins. If any filtration of the sample is performed
prior to starting the analysis, those solids should be analyzed separately. The results
from the analysis of these solids should be reported separately (as a suspended activity
concentration for the water volume filtered), but identified with the filtrate results.
1.2. The method provides a very rapid non-radioisotope-specific screen for total
radiostrontium in drinking water and other aqueous samples.
1.3. This method uses rapid radiochemical separations techniques for the determination of
beta-emitting strontium radioisotopes in water samples following a nuclear or
radiological incident. Although this method can detect concentrations of 90Sr on the
same order of magnitude as methods used for the Safe Drinking Water Act (SDWA),
this method is not a substitute for SDWA-approved methods for radiostrontium.
1.4. The method is capable of satisfying a required method uncertainty for 90Sr (total as
90Sr) of 1.0 pCi/L at an analytical action level of 8.0 pCi/L. To attain the stated
measurement quality objectives (MQOs) (see Step 9.2), a sample volume of
approximately 500 mL and a count time of approximately 1.25 hours are
recommended. The sample turnaround time and throughput may vary based on
additional project MQOs, the time for analysis of the final counting form and initial
sample volume. 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 (EPA 2009, reference 16.3).
1.5. This method is intended to be used for water samples that are similar in composition to
drinking water. The rapid 90Sr method was 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 (EPA 2009,
reference 16.3) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP 2004, reference 16.4). The matrix used for the
determination of 90Sr was drinking water from Atlanta, GA. See Appendix C of this
method for a listing of the chemical constituents of the water. Multi-radionuclide
analysis using sequential separation may be possible.
1.6. This method is applicable to the determination of soluble radiostrontium. This method
is not applicable to the determination of strontium isotopes contained in highly
insoluble particulate matter possibly present in water samples contaminated as a result
of a radiological dispersal device (RDD) event.
1.7. Sequential, multi-radionuclide analysis may be possible by using this method in
conjunction with other rapid methods.
2. Summary of Method
2.1. Strontium is isolated from the matrix and purified from potentially interfering
radionuclides and matrix constituents using a strontium-specific, rapid chemical
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separation method. The sample is equilibrated with strontium carrier, and concentrated
by Sr/BaCOs coprecipitation. If insoluble residues are noted during acid dissolution
steps, the residue and precipitate mixture is digested in 8 M HNOs to solubilize
strontium. The solution is passed through a Sr-Resin™ extraction chromatography
column1 that selectively retains strontium while allowing most interfering radionuclides
and matrix constituents to pass through to waste. If present in the sample, residual
plutonium and several interfering tetravalent radionuclides are stripped from the
column using an oxalic/nitric acid rinse. Strontium is eluted from the column with 0.05
M HNOs and taken to dryness in a tared, stainless steel planchet. The planchet
containing the strontium nitrate precipitate is weighed to determine the strontium yield.
2.2. The sample test source is promptly counted on a gas flow proportional counter to
determine the beta emission rate, which is used to calculate the total radiostrontium
activity.
2.2.1. This test assumes that it is reasonable to assume the absence of 89Sr in the
sample. In such cases, a total radiostrontium analysis will provide for a specific
determination of 90Sr in the sample. The same prepared sample test source can
be recounted after -1-21 days to verify the total radiostrontium activity. If the
initial and second counts agree, this is an indication that 89Sr is not present in
significant amounts relative to 90Sr (within the uncertainty of the measurement).
2.2.2. Computational methods are available for resolving the concentration of 89Sr and
90Sr from two sequential counts of the sample. An example of an approach that
has been used successfully at a number of laboratories is presented in Appendix
B to this method. It is the responsibility of the laboratory, however, to validate
this approach prior to its use.
3. Definitions, Abbreviations, and Acronyms
3.1. Analytical Protocol Specification (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 decisionmaker to choose one of the alternative
actions.
3.3. Analytical Decision Level (ADL). The analytical decision level refers to the value that
is less than the AAL based on the acceptable error rate and the required method
uncertainty.
3.4. 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).
3.5. Multi-Agency Radiological Analytical Laboratory Protocol Manual (see Reference
16.4.)
1 Sr-Resin™ is a proprietary extraction chromatography resin consisting of octanol solution of 4,4'(5')-bis (t-butyl-
cyclohexano)-18-crown-6-sorbed on an inert polymeric support. The resin can be employed in a traditional
chromatography column configuration (gravity or vacuum) or in a flow cartridge configuration designed for use
with vacuum box technology. Sr-Resin is available from Eichrom Technologies, Lisle, IL.
90
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
3.6. 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.
3.7. Radiological Dispersal Device (RDD), i.e., a "dirty bomb." This is an unconventional
weapon constructed to distribute radioactive material(s) into the environment either by
incorporating them into a conventional bomb or by using sprays, canisters, or manual
dispersal.
3.8. Required Method Uncertainty (MMR). The required method uncertainty is a target value
for the individual measurement uncertainties and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method uncertainty
is applicable below an AAL.
3.9. Relative Required Method Uncertainty (^R). The relative required method uncertainty
is the WMR divided by the AAL and is typically expressed as a percentage. It is
applicable above the action level.
3.10. 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 in the
method, such as a solid deposited on a filter for alpha spectrometry analysis.
3.11. Total Radiostrontium (also called Total Strontium): A radiological measurement that
does not differentiate between 89Sr and 90Sr. The assumption is that all of the strontium
is in the form of 90Sr. When it is certain that no 89Sr is present, the total radiostrontium
activity is equal to the 90Sr activity and may be reported as such.
4. Interferences
4.1. Radiological
4.1.1. Count results should be monitored for detectable alpha activity and appropriate
corrective actions taken when observed. Failure to address the presence of alpha
emitters in the sample test source may lead to high result bias due to alpha-to-
beta crosstalk.
4.1.1.1. Elevated levels of radioisotopes of tetravalent plutonium, neptunium,
cerium, and ruthenium in the sample may hold up on the column and
co-elute with strontium. The method employs an oxalic acid rinse that
should address low to moderate levels of these interferences in
samples.
4.1.1.2. The resin has a higher affinity for polonium than strontium. Under the
conditions of the analysis, however, polonium is not expected to elute
from the column.
4.1.2. Significant levels of 89Sr in the sample will interfere with the total
radiostrontium analysis.
4.1.2.1. The absence of higher levels of interfering 89Sr may be detected by
counting the sample test source quickly after initial separation
(minimizing ingrowth of 90Y), and then recounting the sample test
source after 1-21 days to verify that the calculated activity does not
change significantly. The presence of 89Sr may be indicated when the
calculated activity of the second count is less than that of the first
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
count by an amount greater than that which can be attributed to
statistical variation in the two analyses.
4.1.2.2. Alternatively, Appendix B provides a numerical approach for the
isotopic determination 89Sr and 90Sr from two sequential counts of the
sample, one immediately following separation, and one after a delay to
allow for ingrowth of 90Y and decay of 89Sr. Note that the approach in
Appendix B must be validated prior to use.
4.1.3. High levels of 210Pb may interfere with low-level strontium analysis due to
ingrowth of short-lived 210Bi during chemical separations. If 210Pb is known to
be present in samples, minimizing the time between the final rinse and the
elution of strontium to less than 15 minutes will maintain levels of interfering
210Bi to less than 0.1% of the 210Pb activity present. The presence or absence of
interfering 210Bi may be determined by recounting the sample test source to
verify the half-life of the nuclide present.
4.1.4. High levels of 228Th or its decay progeny 224Ra and 212Pb may interfere with
low-level strontium determinations due to ingrowth of short-lived decay
products during chemical separations. Monitoring count data for alpha activity
may provide indications of interferences. Minimizing the time between the final
rinse and the elution of strontium from the column to 5 minutes should maintain
levels of interfering 212Pb and 208T1 to less than 2% of the parent nuclide
01 0
activity. The presence or absence of Pb may be determined by recounting the
sample test source to verify the half-life of the nuclide present.
4.1.5. Levels of radioactive cesium or cobalt in excess of approximately 103 times the
activity of strontium being measured may not be completely removed and may
interfere with final results.
4.2. Non-Radiological
4.2.1. Chemical yield results significantly greater than 100% may indicate the
presence of non-radioactive strontium native to the sample. If the quantity of
native strontium in the sample aliquant exceeds -5% of the expected strontium
carrier mass, chemical yield measurements will be affected and chemical yield
corrections lead to low result bias unless the native strontium is accounted for in
the yield calculations. When problematic levels of strontium are encountered,
the native strontium content of the sample can be determined by an independent
spectrometric measurement (such as inductively coupled plasma atomic
emission spectroscopy [ICP-AES] or atomic absorption spectroscopy [AAS],
etc). If the laboratory does not have access to instrumentation processing a split
of the sample without the addition of strontium carrier may be used to obtain an
estimate of the native strontium content of the sample.
4.2.2. Sr-Resin™ has a greater affinity for lead than for strontium. Lead will
quantitatively displace strontium from the column when the two are present in
combined amounts approaching or exceeding the capacity of the column. If the
combined quantity of lead and strontium carrier in the sample exceeds the
capacity of the column, decreased strontium yields will be observed. Decreasing
the sample size will help address samples with elevated levels of lead.
90
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4.2.3. High levels of calcium, barium, magnesium, or potassium may compete with
strontium for uptake on the resin leading to low chemical yield. One should
consider that yield results will overestimate the true strontium yield and cause a
low result bias if these interfering matrix constituents are present as significant
contaminants in the final sample test source.
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.
5.1.2. Refer to the laboratory chemical hygiene plan for general chemical safety rules
5.2. Radiological
5.2.1. Hot Particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles" (DRPs), will
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 or finer filter
will minimize the presence of these particles.
5.2.1.2. 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 causing contamination.
5.2.1.3. Filter media should be individually surveyed for the presence of these
particles, and this information reported with the final sample results.
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:
None noted.
6. Equipment and supplies
6.1. Analytical balance with 0.0001-g readability or better.
6.2. Centrifuge able to accommodate 250-mL flasks and 50-mL centrifuge tubes.
6.3. Centrifuge flasks, 250 mL, disposable.
6.4. Centrifuge tubes, 50 mL, disposable.
6.5. Low background gas flow proportional counter.
6.6. Stainless steel planchets or other sample mounts: ~2-inch diameter.
6.7. Vacuum box may be procured commercially, or constructed. Setup and use should be
consistent with manufacturer instructions or laboratory SOP.
6.8. Vacuum pump or laboratory vacuum system.
7. Reagents and Standards:
Note: All reagents are American Chemical Society (ACS) reagent grade or equivalent unless otherwise
specified.
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
Note: Unless otherwise indicated, all references to water should be understood to mean Type I Reagent
water (AS TMD1193).
7.1. Barium carrier solution (10 mg Ba/mL, standardization not required): Dissolve 19 g
Ba(NO3)2 in water add 20 mL concentrated HNO3 and dilute to 1 L with water.
7.2. Ethanol, reagent 95% (C2HsOH), available commercially.
7.3. Nitric Acid, HNO3 (15.8M), concentrated, available commercially.
7.3.1. Nitric acid (8 M): Add 506 mL of concentrated HNO3 to 400 mL of water and
dilute to 1 L with water.
7.3.2. Nitric acid (3 M): Add 190 mL of concentrated HNO3 to 800 mL of water and
dilute to 1 L with water.
7.3.3. Nitric acid (0.1 M): Add 6.3 mL of concentrated HNO3 to 900 mL of water and
dilute to 1 L with water.
7.3.4. Nitric acid (0.05 M): Add 3.2 mL of concentrated HNO3 to 900 mL water.
Dilute to 1 L with water.
7.4. Nitric acid (3M)/oxalic acid solution (0.05 M): Add 190 mL of concentrated HNO3
(7.3) and 6.3 grams of oxalic acid dihydrate (C2H2O4-2H2O), to 800 mL of
demineralized water and dilute to 1 L with de-ionized water.
7.5. Sodium carbonate (2 M): Dissolve 212 g anhydrous Na2CO3 in 800 mL of water, then
dilute to 1 L with water.
7.6. Sodium hydroxide (12 M): Dissolve 480 g of sodium hydroxide (NaOH) in 500 mL of
water and dilute the solution to 1 L in water.
Caution: The dissolution of NaOH is strongly exothermic. Take caution to prevent boiling when
preparing this solution. Use of a magnetic stirrer is recommended. Allow to cool prior to use.
7.7. Sr-Resin™ columns,2 -0.7 g resin, small particle size (50-100 |j,m), in appropriately
sized column or pre-packed cartridge.
7.8. Strontium carrier solution, 5.00 mg/mL in 0.1-M HNO3, traceable to a national
standards body such as NIST or standardized at the laboratory by comparison to
independent standards.
7.8.1. Option 1: Dilute elemental strontium standard to a concentration of 5.00 mg/mL
(or mg/g) in 0.1-M HNO3.
7.8.2. Option 2: To 200 mL de-ionized water, add 6.3 mL HNO3 and approximately
12.07 g of strontium nitrate (Sr(NO3)2 dried to constant mass and the mass
being determined to at least 0.001 g). Dilute to 1000 mL with water. Calculate
the amount of strontium nitrate/mL actually present and verify per Step 7.8.3.
7.8.3. Prior to use, verify the strontium carrier solution concentration as by
transferring at least five 1.00-mL portions of the carrier to tared stainless steel
planchets. Evaporate to dryness on a hotplate or under a heat lamp using the
same technique as that used for samples. Cool in a desiccator and weigh as the
nitrate to the nearest 0.1 mg. The relative standard deviation for replicates
2 Available from Eichrom Technologies, Inc., Lisle IL.
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
should be less than 5% and the average residue mass within 5% of the expected
value.
7.9. 90Sr standard solution (carrier free), traceable to a national standards body such as
NIST, in 0.5 M HNO3 solution.
Sample Collection, Preservation and Storage
8.1. Samples should be collected in 1-L plastic containers.
8.2. No sample preservation is required if sample analysis is initiated within 3 days of
sampling date/time.
If the sample is to be held for more than three days, HNOs shall be added until pH<2.
If the dissolved concentration of strontium 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 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 manual and
procedures shall be used to determine acceptable performance for this method.
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 a 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 laboratory 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 may be included as a batch quality control sample if
there is concern that matrix interferences, such as the presence of elemental
strontium in the sample, may compromise chemical yield measurements, or
overall data quality.
9.2. This method is capable of achieving a Z/MR of 1.0 pCi/L at or below an action level of
8.0 pCi/L. This may be adjusted if the event-specific MQOs are different.
9.3. This method is capable of achieving a ^MR 13% above 8 pCi/L. This may be adjusted if
the event-specific MQOs are different.
9.4. This method is capable of achieving a required minimum detectable concentration
(MDC)of l.OpCi/L.
10. Calibration and Standardization
10.1. The effective detection efficiency for total radiostrontium (referenced to 90Sr) is
calculated as the weighted sum of the 90Sr and 90Y efficiencies that reflects the relative
proportions of 90Y and 90Sr based on the 90Y ingrowth after 90Sr separation.
10.2. Set up, operate, and perform quality control for gas-flow proportional counters (GPC)
in accordance with the laboratory's quality manual and standard operating procedures,
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
and consistent with ASTM Standard Practice D7282, Sections 7-13 (see reference
16.5).
10.3. See Appendix A for details on calibration/standardization of the GPC specific to 90Sr
and90Y.
11. Procedure
11.1. For each sample in the batch, aliquant 0.5 L of raw or filtered water into a beaker.
Add concentrated HNOs with mixing to bring the solution to a pH less than 2.0.
Note: Smaller or larger aliquants may be used if elevated sample activity is present or as needed
to meet detection requirements or MQOs. Method validations must be conducted using a volume
equivalent in size to the sample size to be usedr
11.2. Add 1.00 mL (using a volumetric pipette) of 5 mg/mL strontium carrier and 0.5 mL
barium carrier. Record the volume of strontium carrier added and the associated
uncertainty of the mass of strontium added.
11.3. Place the beaker on a hotplate (for aliquants of 0.2 L a centrifuge cone in a hot water
bath may also be used) and heat the solution to near boiling with occasional stirring.
11.4. Add -0.4-0.5 mL (8 -10 drops) 0.1% phenolphthalein indicator solution per 200 mL
of sample. Add 12 M NaOH slowly with occasional stirring until a persistent pink
color is obtained.
Note: Additional phenolphthalein solution may be used if needed to provide a clear indication
that the pH is above ~8.3. A slight excess of NaOH may be added.
11.5. Add 30 mL of 2-M Na2CC>3 to the sample and digest for 15 minutes with occasional
stirring. Remove the sample from the hot plate and allow the solution to cool and the
precipitate to settle.
Note: Samples may be placed in an ice bath to expedite the cooling process.
Note: If greater than a 0.2-L aliquant is used, the supernatant solution is decanted or an
aspirator line used to remove as much supernatant solution as possible prior to transfer to a
centrifuge tube.
11.6. Transfer the sample to a centrifuge tube and centrifuge for 3 to 5 minutes at 1500-
2000 rpm. Discard supernatant solution.
11.7. Add 5 mL of 8-M HNOs to the centrifuge tube and vortex to dissolve the precipitate
containing Sr.
11.8. If there are no undissolved solids visible in the sample and the sample is not from an
ROD, or there is no reason to possibly suspect highly intractable material to be
present (e.g., insoluble ceramics), proceed with Step 11.11.
11.9. If the sample contains undissolved solids or may contain intractable material, cover
the tube to minimize evaporation of the solution and digest the solution on a hot water
bath for 30 minutes. Allow to cool.
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
11.10. If solids persist, remove by filtering solution through a glass fiber filter (1 urn or
finer). The filter containing the solids should be analyzed separately for gross beta
activity (90Sr efficiency) to determine whether the AAL may be exceeded
(screening ADLs apply). The solution containing soluble strontium is retained as
load solution for Step 11.13.
Note: See Section 12.3.2 for reporting results when liquid and solid fractions are analyzed
separately.
11.11. Set up a vacuum box for Sr-Resin™ columns or cartridges with minimum 10-15
mL reservoirs according the manufacturer's instructions or laboratory SOP. The
initial configuration should permit column effluents during the preconditioning,
sample loading and rinses (Steps 11.12- 11.16) to be discarded to waste.
11.12. Add 5 mL of 8-M HNOs to precondition the column. Adjust the vacuum as
necessary to maintain flow rates at < 3 mL/min. Discard preconditioning solution
effluent.
Note: Unless otherwise specified in the procedure, use a flow rate of ~ 1 mL/min for load and
strip solutions and ~ 3 mL/min for rinse solutions.
11.13. Decrease the vacuum to obtain flow rates of < 1 mL/min. Load the sample from
Step 11.8 or 11.10 into the column reservoir. When the solution reaches the top
surface of the resin proceed with the next step. Discard column effluent.
11.14. Adjust the vacuum as necessary to maintain flow rates at < 3 mL/min. Rinse
centrifuge tube with three successive 3 mL portions of 8-M HNCh adding the next
one after the previous one reaches the top of the resin column. Discard column
effluent.
11.15. If plutonium, neptunium, or radioisotopes of ruthenium or cerium may be present in
the sample, add 10 mL 3-M HNOs - 0.05-M oxalic acid solution to each column.
Allow the solution to completely pass through the column prior to proceeding.
Adjust the vacuum as necessary to maintain flow rates at < 3 mL/min. Discard
column effluent.
11.16. Remove residual nitric/oxalic acid solution with two 3 mL rinses of 8-M HNCh,
allowing each rinse solution to drain before adding the next one. Adjust the vacuum
as necessary to maintain flow rates at < 3 mL/min. Record time and date of the end
of last rinse to the nearest 15 minutes as t\, "time of strontium separation." Discard
column effluent.
11.17. Place clean 50 mL centrifuge tubes beneath the columns to catch the strontium
eluate before proceeding to the next step.
11.18. Decrease the vacuum as necessary to maintain flow rates at < 1 mL/min. Elute
strontium from the columns by adding 10 mL of 0.05-M HNOs.
11.19. Preparation of the STS and determination of chemical yield
11.19.1. Clean and label a stainless steel planchet for each STS.
11.19.2. Weigh and record the tare mass of each planchet to the nearest 0.1 mg.
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11.19.3. Transfer the strontium eluate from Step 11.18 to the planchet and take to
dryness on a hotplate or under a heat lamp to produce a uniformly distributed
residue across the bottom of the planchet.
11.19.4. When dry, place the sample in an oven at 105-110 °C until shortly before
sample test sources are ready for weighing. At that point, remove the STS
from the oven and allow it to cool in a desiccator before weighing.
11.19.5. Weigh and record the gross mass of each planchet to the nearest 0.1 mg.
Note: If the laboratory cannot operationally ensure that the precipitate has been
dried to constant mass, the mass stability of the precipitate should be demonstrated
by reheating the precipitate in an oven at 105-110 °C and reweighing. Since sample
self-attenuation is not a significant factor in the detection efficiency, the sample may
be counted prior to completion of this step if desired.
11.19.6. Calculate the chemical yield as presented in Section 12 of this method.
11.20. Counting the Sample Test Source
11.20.1. On a calibrated gas-flow proportional detector that has passed all required
daily performance and background checks, count the STS for a period as
needed to satisfy MQOs.
11.20.1.1. If the presence of 89Sr cannot be excluded, and total
radiostrontium is being determined as a screen for the presence
of 89Sr or 90Sr, count the STS as soon as practicable after
preparation to minimize the ingrowth of 90Y into the STS.
11.20.1.2. If the presence of 89Sr can be excluded, total radiostrontium
will provide isotopic 90Sr results and the STS may be counted
at any time after preparation.
11.20.2. Calculate the total radiostrontium (90Sr) sample results using calculations
presented in Section 12.
12. Data Analysis and Calculations
12.1. Calculation of Total Radiostrontium
12.1.1. When a sample is analyzed for total radiostrontium (equivalent 90Sr), the
effective efficiency is calculated as follows:
Sr ~ &Sr90 ' V ^ /~ £Y90 (1)
where
£xotai sr = effective detection efficiency for total radiostrontium
£sr9o = final 90Sr detection efficiency
£Y9o = final 90Y detection efficiency
AY9o = decay constant for 90Y, 3.008x 10~6 s"1
t\ = date and time of the Sr/Y separation
h = date and time of the midpoint of the count
Note: The elapsed time between the sample count and the reference date must be
calculated using the same time units as the decay constant.
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12.1 .2. The standard uncertainty of the effective efficiency is calculated as
follows:
al Sr) = '(^o) + l - e-^O?™) + 2l - e-^u(ssi90^90) (2)
where
^ (.** Sr90 3 ^ Y90 )~ ^ \^ Sr90 ' ^ Y90 / ^ V^ Sr90 / ^ \^ Y90 /
Note: This term is derived during calibrations in Appendix A, Section 4.
90Sr is calculated as follows:
12.1.3. The total radiostrontium activity concentration (^Ciotai sr) equivalent to
follows
7? — 7?
Total Sr
where
£)F = e"^90^1"'^ (4)
and where
RH = beta gross count rate for the sample (cpm)
Rb = beta background count rate (cpm)
stotai sr = effective efficiency of the detector for total strontium
referenced to 90Sr
Y = fractional chemical yield for strontium
V = volume of the sample aliquant (L)
DF = correction factor for decay of the sample from its
reference date until the midpoint of the total strontium
count
Asr9o = decay constant for 90Sr, 7.642x 1(T10 s"1
t0 = reference date and time for the sample
h = date and time of the Sr/Y separation
Note: The elapsed time between the sample count and the reference date must be
calculated using the same time units as the decay constant
12.1 .4. The standard counting uncertainty of the total radiostrontium activity
concentration, WccC^Cxotai sr) is calculated as follows:
McC \AL Total Sr) ~
t, ^
2.22xsTotalSlxYxVxDF
(5)
where:
4 = Duration of the sample count (min)
t\, = Duration of the background subtraction count (min)
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12.1.5. The combined standard uncertainty (CSU) for the total radiostrontium
activity concentration, z/cC^Crotai sr), is calculated as follows:
U(AC } ~ 2 (AC } + AC2 1*™*
Mc^UTotalSr^ ~, PcC ^U Total Sr J + ^U Total Sr 2 +
^Total Sr
where:
w(Y) = standard uncertainty of fractional chemical yield for strontium
= standard uncertainty of the volume of the sample aliquant (L)
12.1.6. If the critical level concentration (Sc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations:3
0.4 x p- -1 + 0.677 x 1 + ^ +1.645 x l(Rb tb + 0.4)x ^- x 1 + ^
Vb j (. lb) V tb (. tb.
tsx2.22xsTotalSlxYxVxDF
MDC =
rrt
tsx2.22xsTotalSlxYxVxDF
(8)
12.2. Chemical Yield for Strontium
12.2.1. Calculate the chemical yield for strontium using the gravimetric data
collected in Step 11.18:
Y=7v"TcV (9)
where:
Y = strontium yield, expressed as a fraction
ms = mass of Sr(NC>3)2 recovered from the sample (g)
^sr(No3)2 = gravimetric factor for strontium weighed as the nitrate,
414.0mgSr/gSr(NO3)2
cc = Sr mass concentration in the strontium carrier solution
(mg/mL)
FC = volume of strontium carrier added to the sample (mL)
cn = Sr mass concentration native to the sample - if
determined (mg/L)
V = volume of sample aliquant (L)
12.2.2. Calculate the standard uncertainty of the yield as follows:
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. The formulations presented assume a = 0.05, ft = 0.05 (with Z!_a = Z!_P = 1.645), and d = 0.4.
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(10)
f,+c»
where
u(-) = standard uncertainty of the quantity in parentheses,
eses.
u(-) = standard uncertainty of the quantity in parentheses,
Mr(-) = relative standard uncertainty of the quantity in parenthe
12.3. Results Reporting
12.3.1. Unless otherwise specified in the APS, the following items should be
reported for each result:
12.3.1.1. Result for total radiostrontium (Step 12. 1 .3) in scientific
notation ± 1 combined standard uncertainty.
12.3.1.2. Volume of sample aliquant and any dilutions used.
12.3.1.3. Yield of tracer and its uncertainty.
12.3.1.4. Case narrative
12.3.1.5. The APS may specify reporting requirements for samples
originating from an RDD or other event where intractable
material (e.g., strontium titanate) may be present. If specific
guidance is not provided, but intractable materials are likely
present in samples, the results for soluble strontium (from the
aqueous phase) should be reported per Step 12.3.2.
12.3.2. If solid material was filtered from the solution and analyzed separately, the
gross beta results from the direct count of filtered solids should be
calculated as "gross beta (90Sr)" or "gross beta equivalent 90Sr" and
reported separately in terms of pCi/L of the original volume of sample.
For Example:
90Sr for Sample 12-1-99:
Filtrate result: (1.28 ± 0.15)xl01pCi/L
Gross beta (90Sr) filtered residue result: (2.50 ± 0.30)xlO° pCi/L
13. Method Performance
13.1. Results of method validation performance are to be archived and available for
reporting purposes.
13.2. Expected turnaround time per sample or per batch (See Figure 17.4 for typical
processing times (assumes samples are not from RDD).
13.2.1. Preparation and chemical separations for a batch of 20 samples can be
performed by using two vacuum box systems (12 ports each).
simultaneously, assuming 24 detectors are available. For an analysis of a
500 mL sample aliquant, sample preparation and digestion should take
-3-4 h.
13.2.2. Purification and separation of the strontium fraction using cartridges and
vacuum box system should take -0.5-1.2 h.
13.2.3. Sample test source preparation takes -0.75 - 1.5 h.
90
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
13.2.4. A 100-minute counting time is sufficient to meet the MQO listed in Step
9.2, assuming 0.5 L aliquant, a background of 1 cpm, detector efficiency
of 0.3-0.4, and radiochemical yield of at least 0.5.
13.3. Total radiostrontium (90Sr) data reduction should be achievable between 6 and 9
hours after the beginning of the analysis.
13.4. The sample may be recounted following a delay of 1-21 days to verify the
radiochemical purity of 90Sr. If the source contains pure 90Sr, the total
radiostrontium activity calculated from the two counts should agree within the
uncertainty of the measurements. Minimizing the time between the chemical
separation of Sr and the initial count, longer count times, and increasing the delay
between the two counts, will minimize the overall uncertainty of the data and
provide more sensitive and reliable measures of the radiochemical purity of the
STS.
Note: The 89Sr and 90Sr may be determined from two consecutive counts of the source -
calculations are presented in Appendix B. This approach must be validated prior to use.
14. Pollution Prevention
14.1. The use of Sr-Resin™ reduces the amount of acids and hazardous metals that would
otherwise be needed to co-precipitate and purify the sample and prepare the final
counting form.
15. Waste Management
15.1. Nitric acid and hydrochloric acid wastes should be neutralized before disposal and
then disposed in accordance with prevailing laboratory, local, state and federal
requirements.
15.2. Initial column effluents contain mg/mL levels of barium and should be disposed in
accordance with prevailing laboratory, local, state and federal requirements.
15.3. Final precipitated materials may contain radiostrontium and should be treated as
radioactive waste and disposed in accordance with the restrictions provided in the
facility's radioactive materials license and any prevailing local restrictions.
15.4. Used resins and columns should be considered radioactive waste and disposed of in
accordance with restriction provided in the facility's radioactive materials license
and any prevailing local restrictions.
16. References
16.1. SRW04-11, "Strontium 89, 90 in Water," Eichrom Technologies, Inc., Lisle,
Illinois (February 2003).
16.2. "Rapid Column Extraction Method for Actinides and 89/90Sr in Water Samples,"
S.L. Maxwell III. Journal of Radioanalytical and Nuclear Chemistry 267(3): 537-
543 (Mar 2006).
16.3. U.S. Environmental Protection Agency (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.
Available at:www.epa.gov/narel/incident guides.html.
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
16.4. 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 at: www.epa.gov/radiation/
marlap/index.html.
16.5. 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.
16.6. SR-04, "Radiochemical Determination of Radiostrontium in Water, Sea Water, and
Other Aqueous Media," Eastern Environmental Radiation Facility (EERF)
Radiochemistry Procedures Manual, Montgomery, AL, EPA 520/5-84-006 (August
1984).
16.7. ASTM Dl 193, "Standard Specification for Reagent Water," ASTM Book of
Standards 11.02, current version, ASTM International, West Conshohocken, PA
16.8. Nuclear data from NUDAT 2.3 and the National Nuclear Data Center at
Brookhaven National Laboratory; available at www.nndc.bnl.gov/nudat2/indx_
dec.isp, database version of 6/30/2009.
90
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Total Radiostrontium ( Sr) in Water: Rapid Method for High-Activity Samples
17. Tables, Diagrams, Flow Charts and Validation Data
17.1. Validation Data
This section intentionally left blank.
17.2. Nuclide Decay and Radiation Data
Table 17.1. Decay and Radiation Data
Nuclide
90Sr
90y
89Sr
Half-life
(days)
1.052E+04
2.6667
50.53
X
(s-1)
7.642xlO"10
3.005xlO"6
1.587X10'7
Abundance
1.00
1.00
1.00
Pmax
(MeV)
0.546 MeV
2.280 MeV
1.495 MeV
ftavg
(MeV)
0.196 MeV
0.934 MeV
0.585 MeV
17.3. Ingrowth and Decay Curves and Factors
In-Growth Curve for 90Y in 90Sr
100
200 300 400 500
Time Elapsed After Sr-90 Separation (h)
^^^—Y-90 Sr-90 • • • Beta Activity
600
700
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Total Radiostrontium ( Sr) in Water: Rapid Method for High-Activity Samples
Table 17.2. Total Beta Activity Ingrowth Factors for 90Y in 90Sr
Ingrowth time elapsed (hours)
Factor
Ingrowth time elapsed (hours)
Factor
0.25
0.003
^mmmimsfffi
144
0.790
2
0.021
>if|f:if{i|i«i««|
192
0.875
4
0.042
240
0.926
12
0.122
320
0.969
24
0.229
400
0.987
48
0.405
480
0.994
72
0.541
560
0.998
96
0.646
640
0.999
Factor = ( Y activity/ Sr activity at zero hours of ingrowth)
o 0.5 -
89r
Decay Curve for Sr
100 200 300 400
Time Elapsed since collection (h)
— Sr-89 Activity
500
600
700
89r
Table 17.3. Decay Factors for aySr
Decay time elapsed (hours) 0.25 2
Factor 1.000 0.999
Decay time elapsed (hours) 144 192
Factor 0.921 0.896
4 12 24 48 72 96
0.998 0.993 0.986 0.973 0.960 0.947
240 320 400 480 560 640
0.872 0.833 0.796 0.760 0.726 0.694
Factor = (89Sr activity/89Sr activity at zero hours of ingrowth)
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Total Radiostrontium ( Sr) in Water: Rapid Method for High-Activity Samples
89C j 90C
17.4. Decay Schemes for sySr and yuSr
"Sr and 9°Sr Decay Scheme
t,,= 50.53 d
p = 0.55 MeV
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Total Radiostrontium ( Sr) in Water: Rapid Method for High-Activity Samples
17.5. Process Flow with Typical Processing Times (assumes no filtration necessary)
Elapsed
Time
Hrs
1.0
3.0
3.5
4.0
4.5
5.5
6.0
8.7
27-90
Aliquant sample, add HN03 to pH <2; Add Sr
and Ba carriers (11.1 -11.2)
Heat sample (11.3)
Add indicator and adjust to phenolphthalem
endpoint with NaOH (11.4)
Add Na2CQ3 to precipitate; Digest and allow to
cool; Settle/centrifuge (11.5-11.6)
May
intractable Sr
be present?
(11.8)
ndissolved
residue
present?
(11.10)
Cover and digest
sample for 30
minutes
Continue with 11.10
(11.8)
Load sample onto prepared
column at £1 rnUmin.
(11.13)
Prepare and
precondition column
with 5 ml_8M HN03
(11.11-11.12)
Analyze filter for
gross beta.
Evaluate results
against 9DSr
Screening ADLs.
(11.10)
Sr Resin
Column
Adjust flow to S3 rnL/min. Rinse
centrifuge tube with three 3-mL rinses of
8 M HN03 adding each to column (11.14)
If Ce, Ru, Pu.or Np may be present, strip
with 10 mLHN03/oxalic reagent (11.15)
twoSM HN03 rinses. Record t, (11.16)
Replace tube to retain eluate. Adjust flow
to £1 mUmin. Elute Sr with two 5 ml
portions of0.05MHN03 (11.17-11.18)
Retain Sr eluate (11.17-11.18)
Discard precondition (11.12),
load (11.13) and strip and rinse
(11.14-11.16) effluents
Quantitatively transfer and evaporate Sr eluate onto clean, tared planchet (11.19.1-11.19.4)
Dry to constant mass and weigh to determine chemical yield (11.19.5-11.19.6)
Beta Count with Gas Flow Proportional Counter to determine Total Sr activity
(11.20.1-11.20.2)
Recount to verify for MSr if required by APS
(11.20.1-11.20.2)
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
Appendix A
Method and Calculations for Detector Calibration
90C
Al .The effective detection efficiency for total radiostrontium (referenced to Sr) is calculated as
the weighted sum of the 90Sr and 90Y efficiencies that reflects the relative proportions of 90Y
and 90Sr based on the 90Y ingrowth after strontium separation.
Note: While 89Sr efficiency calibration is not needed unless 89Sr analysis will be performed, instructions
for preparation are provided to support the two count approach should this option be desired.
ALL Due to the low mass of carrier used for this method, self-absorption effects may be
assumed to be constant. Calibrate each detector used to count samples according to
ASTM Standard Practice D7282, Section 16, "Single Point Efficiency or Constant
Test Mass for a Specific Radionuclide" and the instructions below.
A1.2. Prepare a blank and at least three working calibration sources (WCS) for 90Sr and
90Y, and 89Sr (if needed) as follows:
Al .2.1. The 90Sr and 89Sr radioactive standard solutions used to prepare WCSs
shall be traceable to a national standards body such as NIST and shall
originate from a standards supplier (or lot) different from standards used
for calibration verification and batch quality controls. The standards
should be diluted in nitric acid.
Al.2.2. The planchets used for the sources shall be of the same size, materials and
type as those used for the analysis of STSs.
Al.2.3. Preparation of 89Sr WCSs (if needed): 89Sr standard solution (in 0.5-M
HNOs) is evaporated to dryness in a stainless steel planchet as follows:
Al.2.3.1. For each 89Sr WCS to be prepared, and for the associated
blank, add a strontium carrier to 10 mL of 0.05-M HNOs in a
disposable 50-mL centrifuge tube. The amount of carrier
should be adjusted to approximate the amount expected to be
recovered from routine samples.
Note: If the average recovery has not been determined, the laboratory
may assume 85% chemical yield for determining the amount of carrier
to use in Step 1.2.3.1.
Note: If the 89Sr standard contains residual chloride, it will attack the
surface of the planchet and compromise the quality of the calibration
standard. In such cases, convert the aliquant of standard solution to a
nitrate system by adding 1 mL concentrated HNO3 and taking to
dryness 2 times prior to quantitatively transferring the solution to the
planchet.
Al.2.3.2. For each WCS, add a precisely known amount of traceable 89Sr
solution to a 50-mL centrifuge tube. Sufficient activity must be
present at the point of the count to permit accumulation of
greater than 10,000 net counts in a counting period deemed to
be reasonable by the laboratory. The minimum activity used,
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however, should produce WCS count rates at least 20 times the
background signal but not greater than 5000 cps.
Al .2.3.3. Mix the solution and quantitatively transfer each WCS and the
blank to respective clean stainless steel counting planchets
using three rinses of 0.05-M HNOs.
Al .2.3.4. Evaporate to dryness using the same techniques used for
sample test sources.
Al.2.3.5. For each detector to be calibrated, count three 89Sr WCSs for
sufficient time to accumulate at least 10,000 net counts.
Al .3. Preparation of 90Sr and 90Y WCSs: Separate WCSs for 90Sr and 90Y are prepared by
chemically separating 90Y from a standard solution of 90Sr.
Al .3.1. For each 90Sr WCS to be prepared, and for the associated blank, add 1 mL of
5 mg/mL strontium carrier to a disposable 50-mL centrifuge tube. The
amount of carrier added should correspond to that expected to be recovered
from a routine sample.
Note: If the average recovery has not been determined, the laboratory may assume
85% chemical yield for determining the amount of carrier to use for Step 1.3.1.
Al.3.2. For each 90Sr WCS, add a precisely known amount of traceable 90Sr solution
to a 50-mL centrifuge tube. Sufficient activity should be present at the point
of the count to permit accumulation of greater than 10,000 90Sr and 10,000
90Y net counts in the respective sources in a counting period deemed to be
reasonable by the laboratory. The minimum activity used, however should
produce WCS count rates at least 20 times the background signal but not
greater than 5000 cps.
Al .3.3. Set up one Sr Resin column for each 90Sr WCS and for the associated blank.
Condition each column with 5 mL of 3-M FINOs. Column effluents are
discarded to waste.
Al .3.4. Place a clean centrifuge tube under each column to catch all combined 90Y
effluents.
Note: Unless otherwise specified in the procedure, use a flow rate of ~ 1 mL/min for
load and strip solutions and ~ 3 mL/min for rinse solutions.
Al.3.5. Load the 90Sr solution onto the column. The load solution effluent
containing 90Y is retained.
Al .3.6. Rinse the centrifuge tube with three successive 2-mL portions of 3-M FINOs
adding each of the rinses to the column after the previous rinse has reached
the upper surface of the resin. These effluents also contain 90Y and are
retained.
Al .3.7. Rinse the column with 5 mL of 3 M FINOs and retain the column effluents
containing 90Y. Record the date and time that the final rinse solution leaves
the column to the nearest 5 minutes as ti, "Time of 90Y Separation." Remove
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Total Radiostrontium (90Sr) in Water: Rapid Method for High-Activity Samples
the centrifuge tube that has the combined 90Y effluents. Place a clean tube
under the column to catch the strontium eluate in subsequent steps.
NOTE: From this point, 90Sr must be eluted, and the 90Sr WCS must be prepared and
counted as expeditiously as possible to minimize 90Y ingrowth and necessary
corrections to the efficiency. Counting of the 90Sr WCS should be completed, if
possible, within 3-5 hours but no longer than 10 hours from the time of 90Y
separation. If processing or counting capacity is limited, concentrate resources on 90Sr
WCS and counting first. The 90Y WCS are not compromised by ingrowth but must
only be counted promptly enough to minimize decay and optimize counting statistics.
Al.3.8. Strip strontium from each column by adding 10 mL of 0.05-M HNOs to
each column, catching the effluents containing 90Sr in the centrifuge tube.
Al .3.9. Quantitatively transfer 90Sr and 90Y fractions to respective tared planchets
using three portions of 0.05-M HNOs.
Al.3.10. Evaporate to dryness using the same techniques used for sample test
sources.
Note: Gravimetric measurements may be performed following the counting to
minimize elapsed time between separation and counting.
Al .4. Weigh the 90Sr and 90Y WCS sources and calculate the net residue mass.
Al .4.1. The net mass of the strontium nitrate precipitate shall indicate near
quantitative yield of strontium of 95-103%. If strontium yield falls outside
this range, determine and address the cause for the losses and repeat the
process. The known activity of 90Sr in the standard is corrected for losses
based on the measured chemical yields of the strontium carrier.
Note that no correction shall be applied for values greater than 100% because this will
produce a negative bias in the calibrated efficiency.
Al .4.2. The net residue mass of the 90Y should be equivalent to that of the
associated blank (i.e., -0.0 mg). Higher residue mass may indicate the
breakthrough of strontium and will result in high bias in the 90Y efficiency.
If blank corrected net residue mass exceeds 3% of the strontium carrier
added, determine and address the cause for the elevated mass and repeat the
process.
Al .4.3. Count three 90Sr WCS on each detector to be calibrated, for sufficient time
to accumulate at least 10,000 net counts.
Al .4.4. Count three 90Y WCS on each detector to be calibrated, for sufficient time to
accumulate at least 10,000 net counts.
Al .4.5. Count the associated blanks as a gross contamination check on the process.
If indications of contamination are noted, take appropriate corrective actions
to minimize spread and prevent cross-contamination of other samples in the
laboratory.
Al .5. Verify the calibration of each detector according to ASTM Standard Practice D7282,
Section 16, and the laboratory quality manual and standard operating procedures.
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Al .6. Calculations and data reduction for 90Sr and 90Y calibrations and calibration
verifications are presented in Sections A2, A3, and A4. Calculations for total
radiostrontium are in Section 12.
A2. Calculation of Detection Efficiency for 90Sr
A2. 1 . Calculate the following decay and ingrowth factors for each WCS:
DFs = e-**90^ (Al)
JFY90=l-e-A™fe-'l) (A2)
where
DFS = decay factor for decay of the90 Sr standard from its reference date
until the 90Sr/90Y separation
7FY90 = ingrowth factor for ingrowth of 90Y after the 90Sr/90Y separation
ASr9o = decay constant for 90Sr, 7.642x 1(T10 s"1
AY9o = decay constant for 90Y, 3.005x 10~6 s"1
to = reference date and time for the 90Sr standard
t\ = date and time of the Sr/Y separation
h = date and time of the midpoint of the 90Sr count
Note: The elapsed time between the sample count and the reference date must be calculated
using the same time units as the decay constant
A2.2. Calculate the 90Sr detection efficiency for each WCS:
K — K K
f, - _ s-> b __ 777 y? - _ li __ 7/7 yp
6Sr90,i ~~ ,^> T^ ^.^ il Y90,z A 6Y90 ~ A ^ T^ 7-.^ •" Y90,z A 6Y90
. ,
r0 std X X .,, Sr90 ,td X ,
where
esr9o,! = 9°Sr detection efficiency for the 7th WCS
eY90 = average 90Y detection efficiency (from Step A3. 2)
Rs,i = beta gross count rate for the /'th WCS (in cpm)
R\, = background count rate, in cpm
Rn,t = beta net count rate for the 7th WCS (cpm)
ACsr9o std = activity concentration of the 90Sr standard solution on its
reference date (cpm/mL or cpm/g)
FS;; = amount (volume or mass) of the standard solution added to the
7th WCS
A2.3. Average the efficiencies determined in Step A2.2 for all the WCSs to obtain the final
detection efficiency for 90Sr.
Sr90 ~ Sr90
1 "
= -Ye
wZ-i sr90,i
where
eSr9o,/- = 9°Sr detection efficiency determined for the 7th WCS in A2.2,
77 = number of WCSs prepared and counted.
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A2.4. Calculate the standard uncertainty of the average 90Sr detection efficiency as follows
0 std)
where
= — Y /FY90 , = average value of Y ingrowth factors (A6)
n ,=i
and
u(-} = standard uncertainty of the value in parentheses,
z/r(-) = relative standard uncertainty of the value in parentheses.
A3. Detection Efficiency for 90Y
A3 . 1 . Calculate the 90Y detection efficiency, 6^90,;, for each WCS,
Y90,!
Sr90 std S,i !,,i Sr90 std
where
DFsi = e^r9o(^o) e"^90^"^ (A8)
and
£y9o,i = 9°Y detection efficiency determined for the WCS
Rs,i = beta gross count rate for the /'th WCS (cpm)
Rb = background count rate, in cpm
Rn,t = beta net count rate for the / WCS (cpm)
ACsr90std = activity concentration of the 90Sr standard solution on its reference
date (dpm/mL or dpm/g)
V^i = amount of the standard solution added to the /th WCS (mL or g)
DFSj = combined correction factor for decay of the 90Sr standard in the /'th
WCS from its reference date until 90Y separation, and for the decay
of 90Y from its separation until the midpoint of the count
Asr9o = decay constant for 90Sr, 7.642x 1(T10 s"1
AY9o = decay constant for 90Y, 3 .005 x 1 (T6 s"1
to = reference date and time for the 90Sr standard
t\ = date and time of the90 Y separation
on
h = date and time at the midpoint of the Y count
Note: The elapsed time between the sample count and the reference date must be calculated using the
same time units as the decay constant
A3. 2. Average the efficiencies determined in Step A3.1 to obtain the final detection
efficiency for 90Y.
_ 1
£Y90 ~ S Y90 ~
where
n = number of WCS prepared and counted
= 9°Y detection efficiency determined for the /'th WCS in Step A3. 1
90
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A3 .3 . The combined standard uncertainty of the average efficiency for 90Y including
uncertainty associated with the preparation of the calibration standards is calculated
as follows:
(A10)
where
u(-)
standard uncertainty of the value in parentheses,
relative standard uncertainty of the value in parentheses.
90
90
A4. Calculate the covariance and correlation coefficient for the Sr efficiency and the Y
efficiency:
«(%90^Y9o) = SsmeYgo
and
(Al 1)
where
u(-,-)
r(-,-)
u(-)
ur(-)
u(esm)u(eY90)
estimated covariance of the two quantities in parentheses,
estimated correlation coefficient of the two quantities in
parentheses,
standard uncertainty of the quantity in parentheses,
relative standard uncertainly of the quantity in parentheses.
A5. Detection Efficiency for 89Sr (if needed for Appendix B Calculations)
A5. 1. Calculate the detection efficiency, esr89,;, for each WCS as follows:
(A13)
where
and
DF =
(A14)
'th
std
t0
Sr detection efficiency for the /'t WCS
beta gross count rate for the /'th WCS (cpm)
background count rate, in cpm
activity concentration of the 89Sr standard solution on the reference
date (dpm/mL or dpm/g)
am ount (volume or mass) of the standard solution added to the /th
WCS (mL or g)
correction factor for decay of the 89Sr standard for the /'th WCS
from its reference date until the midpoint of the sample count
decay constant for 89Sr, 1 .372x 10"2 d"1
reference date and time for the 89Sr standard
date and time at the midpoint of the 89Sr count
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A5.1.1. Average the efficiencies determined in Step A5.1 to obtain the final detection
efficiency for 89Sr.
i n
where
£sr89,/ = 89Sr detection efficiency determined for the /'th WCS in Step A5.1,
n = number of WCSs prepared and counted.
A5.1.2.The combined standard uncertainty of the average efficiency for 89Sr including
uncertainty associated with the preparation of the calibration standards is
calculated as follows:
+ 489«r2(^C'sr89std) (Al6)
where
u(-) = standard uncertainty of the value in parentheses,
wr(-) = relative standard uncertainly of the value in parentheses.
90
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Appendix B:
Calculations for Isotopic 89Sr and 90Sr Results
A numerical approach for determining 89Sr and 90Sr activity from a single sample is performed
by a number of laboratories. This presentation, however, allows a more rigorous evaluation of
uncertainties than commonly employed. Lacking this treatment, many labs have found that the
traditional approach (evaluating counting uncertainty for a single count only) has led to
overestimation of the quality of results, and to poor decisions regarding the presence or absence
of low activities of one radioisotope of strontium in the presence of elevated activities of the
second.
These calculations may be valuable to laboratories who wish to determine isotopic 89Sr and 90Sr
in a large number of samples with a minimum of additional effort beyond the initial preparation
and counting of total radiostrontium. Specifically, it involves performing a second count of the
same radiostrontium sample test source (STS) and mathematically resolving the activity of the
two isotopes. Although the STS may be recounted as soon as 1-2 days after the initial count,
resolution is optimized if the two counts span as large a range of the 90Y ingrowth as practicable.
The time elapsed between the chemical separation and the first count should be minimized, while
the second count should optimally proceed as 90Y approaches secular equilibrium with 90Sr but
before significant decay of 89Sr has occurred, for example, after 3-5 half-lives of 90Y have
elapsed (1-2 weeks).
This section may not be employed without complete validation of the approach by the
laboratory, including testing with samples containing ratios of 90Sr relative to 89Sr varying from
pure 90Sr to pure 89Sr.
Bl.The equations in this section are used to calculate the 90Sr and 89Sr activity of a sample from
data generated from two successive counts of the same radiostrontium sample test source.
B 1 . 1 . For each of the two counting measurements (/' = 1 , 2), calculate the following decay
and ingrowth factors:
e-^'-^ (Bl)
e-"-w (B2)
77 _
/Y90,z ~
where:
DFsrs9,i = decay factor for decay of 89Sr from the collection date to the
midpoint of the /th count of the STS
DFSr9o,i = decay factor for decay of 90Sr from the collection date to the
midpoint of the /'th count of the STS
= combined decay and ingrowth factor for decay of 90Sr from the
collection date to the Sr/Y separation and ingrowth of 90Y from the
separation to the midpoint of the /'th count of the STS
= decay constant for 89Sr = 1.58?x 1(T7 s"1
= decay constant for 90Sr = 7.642x 1(T10 s"1
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t0 = collection date and time for the sample
4eP = date and time of the Sr/Y separation
tj = date and time of the midpoint of the /'th count of the STS
Note: The elapsed time between the sample count and the reference date must be calculated
using the same time units as the decay constant
B1.2. For / = 1,2, use the results from Section A5.1 in Appendix A to calculate the
following sensitivity factors:
sSim (B4)
where
at = sensitivity of the count rate in the 7th measurement to 89Sr activity,
bt = sensitivity of the count rate in the /'th measurement to 90Sr activity.
SY9o,i = 90Y efficiency of the detector for the /'th count of the STS,
esr9o,z = 9°Sr efficiency of the detector for the /'th count of the STS.
B1.3. Calculate the standard uncertainties of the sensitivity factors using the equations:
u(sSl^ (B6)
(B7)
where the estimated covariance of the 90Sr and 90Y efficiencies is calculated as
follows:
f \ f \f\f\ /T> O \
and where the estimated correlation coefficient r(eSr9o,z, £Y9o,0 was determined during
the calibration.
B1.4. Calculate the covariances u(ai,a2) and u(b\^>^) as follows:
u(a^ )u(a2), if only one detector is used
ala2 wr2 G4CSr89 std), if two detectors are used
90
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u(bl,b2} =
Sr90,r Y90.2 ~*~ ^^Sr90,r ¥-90,1/^(^90,1' S Y90,l)
,^9o,2u2(s^o,il usingonly one detector (BIO)
usingtwo detectors
2 wr2 G4CSr90std),
89
where
= activity concentration of the 5ySr standard used for calibration
= activity concentration of the 90Sr standard used for calibration
Mr(-) = relative standard uncertainty of the quantity in parentheses
B1.5. For / = 1,2, calculate the net beta count rates, Rn^ and their standard uncertainties:
(B12)
where:
Ra
= net beta count rate for the /th count of the STS (cpm)
= beta gross count rate for the /'th count of the STS (cpm)
= beta background count rate for the /'th count of the STS (cpm)
= sample count time for the 7th count of the STS (min)
= background count time for the /'th count of the STS (min)
89
90
B1.6. Using the values calculated in A5.1 - A5.5, calculate the Sr and Sr activity
concentrations:
AC= ~
SIS9
Sr89
2.22xXxVxY
2.22xXxVxY
where:
= alb2-a2bl
(B13)
V }
(B 14)
(B15)
and where:
2.22 = conversion factor from dpm to pCi
Y = chemical yield for strontium
V = sample volume (L)
B2. The standard counting uncertainties for 89Sr (ueC(AC^9) ) and 90Sr (wcC(y4CSr90) ) are
calculated in units of pCi/L as follows:
urC (A CSrSq ) =
ccv Sr897
222xXxVxY
(B 1 6)
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2.22xXxVxY
(B17)
90C
B3.The combined standard uncertainties (CSU) for Sr and Sr are calculated as follows:
u\V) u2(Y} b22u2(al) + b2u2(a2)-
(B18)
2
' -^l^Q
2
y (b2 ) - 2b1b2 u(b, , b2
1/2
2 a22u2 (aj) + afw2 (a2) - 2ala2 u(^, a2
9 7^2
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Appendix C:
Composition of Atlanta Drinking Water Used for this Study
Metals by ICP-AES
Silicon
Aluminum
Barium
Calcium
Iron
Magnesium
Potassium
Sodium
Inorganic Anions
Chloride
Sulfate
Nitrogen, Nitrate (as N)
Carbon Dioxide
Bicarbonate Alkalinity
Carbonate Alkalinity
Radionuclide
Uranium 234, 235, 238
Plutonium 238, 239/240
Americium 24 1
Strontium 90
Radium 226***
Concentration (mg/L)*
3.18
<0.200
0.0133
9.38
<0.100
<0.500
<0.500
<0.500
12.7
15.6
1.19
23.8
<3.00
Concentration (pCi/L)**
<0.01,<0.01,<0.01
<0.02, <0.02
<0.02
<0.3
0.11 ±0.27
-0.30 ±0.45
Note: Analyses conducted by independent laboratories.
* Values below the reporting level are presented as less than (<) values.
No measurement uncertainty was reported with values greater than the "Reporting
Level."
** Reported values represent the calculated minimum detectable concentration (MDC)
for the radionuclide(s).
*** Two samples analyzed. Expanded uncertainty (k=2) as reported by the laboratory.
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www.epa.gov
February 2010
Revision 0
Rapid Radiochemical Method for
Isotopic Uranium in Water
for Environmental Restoration Following
Homeland Security Events
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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ISOTOPIC URANIUM IN WATER:
RAPID METHOD FOR HIGH-ACTIVITY SAMPLES
1. Scope and Application
1.1. The method will be applicable to samples where the source of the contamination is
either known or unknown sample sources. If any filtration of the sample is performed
prior to starting the analysis, those solids should be analyzed separately. The results
from the analysis of these solids should be reported separately (as a suspended activity
concentration for the water volume filtered), but identified with the filtrate results.
1.2. The method is specific for 238U, 235U, and 234U in drinking water and other aqueous
samples.
1.3. This method uses rapid radiochemical separations techniques for determining alpha-
emitting uranium isotopes in water samples following a nuclear or radiological
0 IS T\ S T\ A
incident. Although the method can detect concentrations of U, U, and U on the
same order of magnitude as methods used for the Safe Drinking Water Act (SDWA),
this method is not a substitute for SDWA-approved methods for isotopic uranium.
1.4. The method is capable of satisfying a required method uncertainty for 238U, 235U, or
234U of 2.6 pCi/L at an analytical action level of 20 pCi/L. To attain the stated
measurement quality objectives (MQOs) (see Section 9.3 and 9.4), a sample volume of
approximately 200 mL and count time of at least 1 hour are recommended. The sample
turnaround time and throughput may vary based on additional project MQOs, the time
for analysis of the final counting form, and initial sample volume. 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 (EPA 2009, reference 16.5).
1.5. The method is intended to be used for water samples that are similar in composition to
drinking water. The rapid uranium method was 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 (EPA 2009,
reference 16.5) and Chapter 6 of Multi-Agency Radiological Laboratory Analytical
Protocols Manual (MARLAP 2004, reference 16.6). The matrix used for the
determination of uranium was drinking water from Atlanta, GA. See the Appendix for a
listing of the chemical constituents of the water.
1.6. Multi-radionuclide analysis using sequential separation may be possible using this
method in conjunction with other rapid methods.
1.7. This method is applicable to the determination of soluble uranium. This method is not
applicable to the determination of uranium isotopes contained in highly insoluble
particulate matter possibly present in water samples contaminated as a result of a
radiological dispersion device (ROD) event.
2. Summary of Method
2.1. This method is based on the sequential elution of interfering radionuclides as well as
other components of the matrix by extraction chromatography to isolate and purify
uranium in order to prepare the uranium for counting by alpha spectrometry. The
method utilizes vacuum assisted flow to improve the speed of the separations. Prior to
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
the use of the extraction resins, a water sample is filtered as necessary to remove any
insoluble fractions, equilibrated with 232U tracer, and concentrated by either
evaporation or calcium phosphate precipitation. The sample test source (STS) is
prepared by microprecipitation with NdF3. Standard laboratory protocol for the use of
an alpha spectrometer should be used when the sample is ready for counting.
3. Definitions, Abbreviations and Acronyms
3.1. Analytical Protocol Specification (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 decisionmaker to choose one of the alternative
actions.
3.3. Analytical Decision Level (ADL). The analytical decision level refers to the value that
is less than the AAL based on the acceptable error rate and the required method
uncertainty.
3.4. 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).
3.5. Multi-Agency Radiological Analytical Laboratory Protocol Manual (M ARL AP) (see
Reference 16.6.)
3.6. Measurement Quality Objective (MQO). MQOs are the analytical data requirements of
the data quality objectives and are project- or program-specific and can be quantitative
or qualitative. These analytical data requirements serve as measurement performance
criteria or objectives of the analytical process.
3.7. Radiological Dispersal Device (RDD), i.e., a "dirty bomb." This is an unconventional
weapon constructed to distribute radioactive material(s) into the environment either by
incorporating them into a conventional bomb or by using sprays, canisters, or manual
dispersal.
3.8. Required Method Uncertainty (WMR). The required method uncertainty is a target value
for the individual measurement uncertainties, and is an estimate of uncertainty (of
measurement) before the sample is actually measured. The required method uncertainty
is applicable below an Analytical Action level.
3.9. Relative Required Method Uncertainty (
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
to enable radionuclide-specific measurements. This method separates these
radionuclides effectively. The significance of peak overlap will be determined
by the individual detector's alpha energy resolution characteristics and the
quality of the final precipitate that is counted.
4.2. Non-Radiological: Very high levels of competing higher valence anions (greater than
divalent such as phosphates) will lead to lower yields when using the evaporation
option due to competition with active sites on the resin. If higher valence anions are
present, the phosphate precipitation option may need to be used initially in place of
evaporation. If calcium phosphate coprecipitation is performed to collect uranium (and
other potentially present actinides) from large-volume samples, the amount of
phosphate added to coprecipitate the actinides (in Step 11.1.4.3) should be reduced to
accommodate the sample's high phosphate concentration.
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.
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. Hot particles (DRPs)
5.2.1.1. Hot particles, also termed "discrete radioactive particles" (DRPs),
will 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 or
finer filter will minimize the presence of these particles.
5.2.1.2. 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 causing contamination.
5.2.1.3. Filter media should be individually surveyed for the presence of
these particles, and this information reported with the final sample
results.
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:
5.3.1. Particular attention should be paid to the discussion 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 obtained and used in strict accordance
with the laboratory safety program specification.
6. Equipment and Supplies
6.1. Analytical balance with 0.01-g readability or better.
6.2. Cartridge reservoirs, 10- or 20-mL syringe style with locking device, or equivalent.
6.3. Centrifuge able to accommodate 250-mL flasks.
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6.4. Centrifuge flasks with 250-mL capacity.
6.5. Filter with 0.45-um membrane.
6.6. Filter apparatus with a 25-mm diameter, polysulfone, filtration chimney, stem support,
and stainless steel support. A single-use (disposable) filter funnel/filter combination
may be used, to avoid cross contamination.
6.7. 25-mm polypropylene filter with 0.1-um pore size.
6.8. Stainless steel planchets or other sample mounts that are able to hold the 25-mm filter.
6.9. Tweezers.
6.10. 100-uL pipette, or equivalent, and appropriate plastic tips.
6.11. 10-mL plastic culture tubes with caps.
6.12. Vacuum pump or laboratory vacuum system.
6.13. Tips, white inner, Eichrom part number AC-1000-IT, or equivalent.
6.14. Tips, yellow outer, Eichrom part number AC-1000-OT, or equivalent.
6.15. Vacuum Box, such as Eichrom part number AC-24-BOX, or equivalent.
6.16. Vortex mixer.
6.17. Miscellaneous labware, plastic or glass, both 250 and 350 mL.
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. All solutions used in microprecipitation should be prepared with water filtered through a 0.45-um
(or better) filter.
7.1. Ammonium hydrogen oxalate (0.1M): Dissolve 6.3 g of oxalic acid (H2C2O4-2H2O)
and 7.1 g of ammonium oxalate ((NH4)2C2O4'H2O) in 900 mL of water, and dilute to 1
L with water.
7.2. Ammonium hydrogen phosphate (3.2 M): Dissolve 106 g of (ML^HPC^ in 200 mL of
water. Heat gently to dissolve and dilute to 250 mL with water.
7.3. Ammonium hydroxide (15 M): Concentrated NFLjOH, available commercially.
7.4. Ammonium thiocyanate indicator (1 M): Dissolve 7.6 g of ammonium thiocyanate
(NFLtSCN) in 90 mL of water and dilute to 100 mL with water. An appropriate quantity
of sodium thiocyanate (8.1 g) or potassium thiocyanate (9.7 g) may be substituted for
ammonium thiocyanate.
7.5. Ascorbic acid (1 M): Dissolve 17.6 g of ascorbic acid (CeHgOe) in 90 mL of water and
dilute to 100 mL with water. Prepare weekly.
7.6. Calcium nitrate (0.9 M): Dissolve 53 g of calcium nitrate tetrahydrate (Ca(NO3)2'4H2O)
in 100 mL of water and dilute to 250 mL with water.
7.7. Ethanol, 100 %: Anhydrous C2HsOH, available commercially.
7.7.1. Ethanol, (-80% v/v): Mix 80 mL 100% ethanol and 20 mL water.
7.8. Ferrous sulfamate (0.6 M): Add 57 g of sulfamic acid ( NF^SOsH) to 150 mL of water
and heat to 70 °C. Slowly add 7 g of iron powder (< 100 mesh size) while heating and
stirring (magnetic stirrer should be used) until dissolved (may take as long as two
hours). Filter the hot solution (using a qualitative filter), transfer to flask, and dilute to
200 mL with water. Prepare fresh weekly.
7.9. Hydrochloric acid (12 M): Concentrated HC1, available commercially.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
7.9.1. Hydrochloric acid (9 M): Add 750 mL of concentrated HC1 to 100 mL of
water and dilute to 1 L with water.
7.9.2. Hydrochloric acid (4 M): Add 333 mL of concentrated HC1 to 500 mL of
water and dilute to 1 L with water.
7.9.3. Hydrochloric acid (1 M): Add 83 mL of concentrated HC1 to 500 mL of water
and dilute to 1 L with water.
7.10. Hydrofluoric acid (28 M): Concentrated HF, available commercially.
7.10.1. Hydrofluoric acid (0.58 M): Add 20 mL of concentrated HF to 980 mL of
filtered demineralized water and mix. Store in a plastic bottle.
7.11. Neodymium standard solution (1000 ug/mL): May be purchased from a supplier of
standards for atomic spectroscopy.
7.12. Neodymium carrier solution (0.50 mg/mL): Dilute 10 mL of the neodymium standard
solution (7.11) to 20.0 mL with filtered demineralized water. This solution is stable for
up to six months.
7.13. Neodymium fluoride substrate solution (10 jig/mL): Pipette 5.0 mL of neodymium
standard solution (7.11) into a 500-mL plastic bottle. Add 460 mL of 1-M HC1 to the
plastic bottle. Cap the bottle and shake to mix. Measure 40 mL of concentrated HF in a
plastic graduated cylinder and add to the bottle. Recap the bottle and shake to mix
thoroughly. This solution is stable for up to six months.
7.14. Nitric acid (16M): Concentrated HNO3, available commercially.
7.14.1. Nitric acid (3 M): Add 191 mL of concentrated HNO3 to 700 mL of water and
dilute to 1 L with water.
7.14.2. Nitric acid (2 M): Add 127 mL of concentrated HNO3 to 800 mL of water and
dilute to 1 L with water.
7.14.3. Nitric acid (0.5 M): Add 32 mL of concentrated HNO3 to 900 mL of water
and dilute to 1 L with water.
7.15. Nitric acid (3 M) - aluminum nitrate (1.0 M) solution: Dissolve 210 g of anhydrous
aluminum nitrate (A1(NO3)3) in 700 mL of water. Add 190 mL of concentrated HNO3
(7.14) and dilute to 1 L with water. An appropriate quantity of aluminum nitrate
nonahydrate (375 g) may be substituted for anhydrous aluminum nitrate.
7.16. Phenolphthalein solution: Dissolve 1 g phenolphthalein in 100 mL 95% isopropyl
alcohol and dilute with 100 mL of water.
7.17. Titanium chloride: 20 % solution, stored in an air-tight container and away from light.
7.18. Uranium-232 tracer solution: 6-10 dpm of 232U per aliquant, activity added known to at
least 5 % (combined standard uncertainty of no more than 5 %).
7.19. UTEVA Resin: 2-mL cartridge, 50-100 ng, Eichrom part number UT-R50-S and UT-
R200-S, or equivalent.
8. Sample Collection, Preservation, and Storage
8.1. No sample preservation is required if sample is delivered to the laboratory within 3
days of sampling date/time.
8.2. If the dissolved concentration of uranium is sought, the insoluble fraction must be
removed by filtration before preserving with acid.
8.3. If the sample is to be held for more than three days, nitric acid shall be added until
pH<2.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
9. Quality Control
9.1. 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 manual and
procedures shall be used to determine acceptable performance for this method.
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 laboratory 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 may be included as a batch quality control sample if
there is concern that matrix interferences, may compromise chemical yield
measurements, or overall data quality.
9.2. The source preparation method should produce a sample test source that produces a
spectrum with the full width at half maximum (FWHM) of 50-100 keV for each peak
in the spectrum (with the exception of 235U). Precipitate reprocessing should be
considered if this range of FWHM cannot be achieved.
9.3. This method is capable of achieving a MMR of 2.6 pCi/L at or below an action level of
20 pCi/L. This may be adjusted if the event-specific MQOs are different.
9.4. This method is capable of achieving a ^MR of 13 % above 20 pCi/L. This may be
adjusted if the event-specific MQOs are different.
9.5. This method is capable of achieving a required minimum detectable concentration
(MDC)of 1.5pCi/L.
10. Calibration and Standardization
10.1. Set up the alpha spectrometry system according to the manufacturer's
recommendations. The energy range of the spectrometry system should at least include
the region between 3-8 MeV.
10.2. Calibrate each detector used to count samples according to ASTM Standard Practice
D7282, Section 18, "Alpha Spectrometry Instrument Calibrations" (see reference 16.3).
10.3. Continuing Instrument Quality Control Testing shall be performed according to ASTM
Standard Practice D7282, Sections 20, 21, and 24.
11. Procedure
11.1. Water Sample Preparation
11.1.1. As required, filter the 100-200 mL sample aliquant through a 0.45-um filter
and collect the sample in an appropriate size beaker.
11.1.2. Acidify the sample with concentrated HNOs. This usually requires adding
about 2 mL of concentrated HNOs per 1000 mL of sample. However, samples
that are initially alkaline, or that may have high carbonate content, may require
substantially more acid. It is important that the pH be verified to be below 2.0,
ensuring that all carbonate (a uranium complexing agent) has been removed.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
11.1.3. Following the laboratory protocol, add 6-10 dpm of 232U as a tracer.
Note: For a sample approximately 100 mL or less, the evaporation option is recommended.
Proceed to Step 11.1.5. Otherwise continue to Step 11.1.4.
11.1.4. Calcium phosphate coprecipitation option
11.1.4.1. Add 0.5 mL of 0.9 M Ca(NO3)2 to each beaker. Place each beaker
on a hot plate, cover with a watch glass, and heat until boiling.
11.1.4.2. Once the sample boils, take the watch glass off the beaker and
lower the heat.
11.1.4.3. Add 2-3 drops of phenolphthalein indicator and 200 |iL of 3.2 M
(NH4)2HPO4 solution.
11.1.4.4. Add enough concentrated NH4OH with a squeeze bottle to reach
the phenolphthalein end point (a persistent pink color) and form
Ca3(PO4)2 precipitate. NH4OH should be added very slowly. Stir
the solution with a glass rod. Allow the sample to heat gently to
digest the precipitate for another 20-30 minutes.
Note: The calcium phosphate precipitation should be completed promptly
following pH adjustment to the phenolphthalein endpoint to minimize
absorption of CO2 and formation of a soluble carbonate complex with U
that will lead to incomplete precipitation of U.
11.1.4.5. If the sample volume is too large to centrifuge the entire sample,
allow precipitate to settle until solution can be decanted (30
minutes to 2 hours) and go to Step 11.1.4.7.
11.1.4.6. If the volume is small enough to centrifuge go to Step 11.1.4.8.
11.1.4.7. Decant supernatant solution and discard to waste.
11.1.4.8. Transfer the precipitate to a 250-mL centrifuge tube, completing
the transfer with a few milliliters of water, and centrifuge the
precipitate for approximately 10 minutes at 2000 rpm.
11.1.4.9. Decant supernatant solution and discard to waste.
11.1.4.10. Wash the precipitate with an amount of water approximately twice
the volume of the precipitate. Mix well using a stirring rod,
breaking up the precipitate if necessary. Centrifuge for 5-10
minutes at 2000 rpm. Discard the supernatant solution.
11.1.4.11. Dissolve precipitate in approximately 5 mL concentrated HNOs.
Transfer solution to a 100 mL beaker. Rinse centrifuge tube with
2-3 mL of concentrated HNOs and transfer to the same beaker.
Evaporate solution to dryness and go to Step 11.2.
11.1.5. Evaporation option to reduce volume and to digest organic components
11.1.5.1. Evaporate sample to less than 50 mL and transfer to a 100 mL
beaker.
Note: For some water samples, CaSO4 formation may occur during
evaporation. If this occurs, use the calcium phosphate precipitation option
in Step 11.1.4.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
11.1.5.2. Gently evaporate the sample to dryness and redissolve in
approximately 5 mL of concentrated HNOs.
11.1.5.3. Repeat Step 11.1.5.2 two more times, evaporate to dryness, and go
to Step 11.2.
11.2. Actinide Separations using Eichrom Resins
11.2.1. Redissolve Ca3(PO4)2 residue or evaporated water sample
11.2.1.1. Dissolve either residue with 10 mL of 3 M HNO3 - 1.0 M
A1(N03)3.
Note: An additional 5 mL may be necessary if the residue volume is large.
11.2.1.2. Add 2 mL of 0.6 M ferrous sulfamate to each solution. Swirl to
mix.
Note: If the additional 5 mL was used to dissolve the sample in Step
11.2.1.1, add a total of 3 mL of ferrous sulfamate solution.
11.2.1.3. Add 1 drop of 1 M ammonium thiocyanate indicator to each
sample and mix.
Note: The color of the solution turns deep red, due to the formation of
soluble ferric thiocyanate complex.
11.2.1.4. Add 1 mL of 1 M ascorbic acid to each solution, swirling to mix.
Wait for 2-3 minutes.
Note: The red color should disappear which indicates reduction of Fe+3 to
Fe+2. If the red color persists, then additional ascorbic acid solution is added
drop-wise with mixing until the red color disappears.
Note: If particles are observed suspended in the solution, centrifuge the
sample at 2000 rpm. The supernatant solution will be transferred to the
column in Step 11.2.3.1. The precipitates will be discarded.
11.2.2. Set up the vacuum box with UTEVA cartridges as follows:
Note: Steps 11.2.2.1 to 11.2.2.5 deal with a commercially available filtration system.
Other vacuum systems developed by individual laboratories may be substituted here as
long as the laboratory has provided guidance to analysts in their use.
11.2.2.1. Place the inner tube rack (supplied with vacuum box) into the
vacuum box with the centrifuge tubes in the rack. Fit the lid to the
vacuum system box.
11.2.2.2. Place the yellow outer tips into all 24 openings of the lid of the
vacuum box. Fit in the inner white tip into each yellow tip.
11.2.2.3. For each sample solution, fit in the UTEVA cartridge on to the
inner white tip.
11.2.2.4. Lock syringe barrels (funnels/reservoirs) to the top end of the
UTEVA cartridge.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
11.2.2.5. Connect the vacuum pump to the box. Turn the vacuum pump on
and ensure proper fitting of the lid.
IMPORTANT: The unused openings on the vacuum box should be sealed.
Yellow caps (included with the vacuum box) can be used to plug unused
white tips to achieve good seal during the separation.
11.2.2.6. Add 5 mL of 3-M HNO3 to the funnel to precondition the UTEVA
cartridge.
11.2.2.7'. Adjust the vacuum pressure to achieve a flow-rate of ~1 mL/min.
IMPORTANT: Unless otherwise specified in the procedure, use a flow rate
of ~ 1 mL/min for load and strip solutions and ~ 3 mL/min for rinse
solutions.
11.23. U separation from Pu, Am using UTEVA resin
11.2.3.1. Transfer each solution from Step 11.2.1.4 into the appropriate
funnel by pouring or by using a plastic transfer pipette. Allow
solution to pass through both the cartridges at a flow rate of ~1
mL/min.
11.2.3.2. Add 5 mL of 3-M HNOs to each beaker as a rinse and transfer each
solution into the appropriate funnel (the flow rate can be adjusted
to ~3 mL/min).
11.2.3.3. Add 5 mL of 3-M HNOs into each funnel as second column rinse
(flow rate ~3 mL/min).
Note: Maintain the flow rate at <3 mL/min in the next several steps.
Note: If a high concentration of 210Po is present in the sample an additional
3 M HNO3 rinse is necessary to eliminate 210Po. Add 30 mL of 3 M HNO3
rinse to each UTEVA cartridge in increments of 10 mL. Continue with Step
11.2.3.4.
11.2.3.4. Pipette 5 mL of 9-M HC1 into each UTEVA cartridge and allow it
to drain. Discard this rinse.
Note: This rinse converts the resin to the chloride system. Some Np may be
removed here.
11.2.3.5. Pipette 20 mL of 5-M HC1 - 0.05 M oxalic acid into each UTEVA
cartridge and allow it to drain. Discard this rinse.
Note: This rinse removes neptunium and thorium from the cartridge. The
9-M HC1 and 5-M HC1 - 0.05 M oxalic acid rinses also remove any residual
ferrous ion that might interfere with micoprecipitation.
11.2.3.6. Ensure that clean, labeled tubes are placed in the tube rack.
11.2.3.7. Pipette 15 mL of 1-M HC1 into each cartridge to strip the uranium.
Allow to drain.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
11.2.3.8. Transfer the eluate containing uranium to a 50-mL beaker. Rinse
the tube with a few milliliters of water and add to the same beaker.
11.2.3.9. Evaporate samples to near soft dryness. If a slight white residue
appears, wet-ash by adding a few mL of HNO3, heating till near
dryness and repeating the process 2-3 times. Once wet-ashing is
complete, convert the sample to the chloride form by treating it 2-
3 times with 1-2-mL portions of HC1 and evaporating to near
dryness.
Note: Do not bake the residue.
11.2.3.10. Allow the beaker to cool slightly and then add a few drops of
concentrated HC1 followed by 1 mL of water.
11.2.3.11. Transfer the solution to a 10-mL plastic culture tube. Rinse the
original sample vessel twice with 1-mL washes of 1-M HC1,
transferring the rinses to a culture tube. Mix by gently swirling the
solution in the tube.
11.2.3.12. Proceed to neodymium fluoride microprecipitation, Step 11.3.
11.2.3.13. Discard the UTEVA cartridge.
11.3. Preparation of the Sample Test Source
Note: Instructions below describe preparation of a single Sample Test Source. Several STSs can be
prepared simultaneously if a multi-channel vacuum box (whale apparatus) is available.
11.3.1. Add 100 jiL of the neodymium carrier solution to the culture tube with a
micropipette. Gently swirl the tube to mix the solution.
11.3.2. Add four drops of 20% TiCb solution to the tube and mix gently. A strong
permanent violet color should appear. If the color fails to appear, add a few
more drops of the TiCb solution to provide the permanent violet color.
11.3.3. Add 1 mL of concentrated HF to the tube and mix well by gently swirling.
11.3.4. Cap the tube and place it a cold-water ice bath for at least 30 minutes.
11.3.5. Insert the polysulfone filter stem in the 250-mL vacuum flask. Place the
stainless steel screen on top of the fitted plastic filter stem.
11.3.6. Place a 25-mm polymeric filter face up on the stainless steel screen. Center
the filter on the stainless steel screen support and apply vacuum. Wet the filter
with 100 % ethanol, followed by filtered Type I water.
Caution: There is no visible difference between the two sides of the filter. If the filter is
turned over accidentally, it is recommended that the filter be discarded and a fresh one
removed from the container.
11.3.7. Lock the filter chimney firmly in place on the filter screen and wash the filter
with additional filtered Type I water wash.
11.3.8. Pour 5.0 mL of neodymium substrate solution down the side of the filter
chimney, avoiding directing the stream at the filter. When the solution passes
through the filter, wait at least 15 seconds before the next step.
11.3.9. Repeat Step 11.3.8 with an additional 5.0 mL of the substrate solution.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
11.3.10. Pour the sample from Step 11.3.4 down the side of the filter chimney and
allow the vacuum to draw the solution through.
11.3.11. Rinse the tube twice with 2 mL of 0.58-M HF, stirring each wash briefly using
a vortex mixer and pouring each wash down the side of the filter chimney.
11.3.12. Repeat rinse using 2-mL filtered Type I water once.
11.3.13. Repeat rinse using 2-mL 80% ethyl alcohol once.
11.3.14. Wash any drops remaining on the sides of the chimney down toward the filter
with a few mL 80% ethyl alcohol.
Caution: Directing a stream of liquid onto the filter will disturb the distribution of the
precipitate on the filter and render the sample unsuitable for a-spectrometry resolution.
11.3.15. Without turning off the vacuum, remove the filter chimney.
11.3.16. Turn off the vacuum to remove the filter. Discard the filtrate to waste for
future disposal. If the filtrate is to be retained, it should be placed in a plastic
container to avoid dissolution of the glass vessel by dilute HF.
11.3.17. Place the filter on a properly labeled mounting disc, secure with a mounting
ring or other device that will render the filter flat for counting.
11.3.18. Let the sample air dry for a few minutes and when dry, place in a container
suitable for transfer and submit for counting.
11.3.19. Count the sample on an alpha spectrometer.
Note: Other methods for STS preparation, such as electroplating or microprecipitation
with cerium fluoride, may be used in lieu of the neodymium fluoride microprecipitation,
but any such substitution must be validated as described in Section 1.4.
12. Data Analysis and Calculations
12.1. Equations for determination of final result, combined standard uncertainty and
radiochemical yield (if required).
The activity concentration of an analyte and its combined standard uncertainty are
calculated using the following equations:
AtxRaxDtxIt
FaxtftxZ)ax/a
and
where:
ACn = activity concentration of the analyte at time of count, (pCi/L)
At = activity of the tracer added to the sample aliquant at its reference date
and time, (pCi)
Ra = net count rate of the analyte in the defined region of interest (ROI), in
counts per second
Rt = net count rate of the tracer in the defined ROI, in counts per second
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
Fa = volume of the sample aliquant, (L)
DI = correction factor for decay of the tracer from its reference date and
time to the midpoint of the counting period
Z)a = correction factor for decay of the analyte from the time of sample
collection (or other reference time) to the midpoint of the counting
period (if required)
/t = 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(Ai) = standard uncertainty of the activity of the tracer added to the sample
(pCi)
w(Fa) = standard uncertainty of the volume of sample aliquant (L)
u(Ra) = standard uncertainty of the net count rate of the analyte, in counts per
second
u(Ri) = standard uncertainty of the net count rate of the tracer, in counts per
second
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 (uc(AC^)) 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 that
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.
12.1.1. The net count rate of an analyte or tracer and the associated standard
uncertainties are calculated using the following equations:
and
V <
where:
u(Rx) = standard uncertainty of the net count rate of tracer or analyte, in
counts per second1
1 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
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
Rx = net count rate of analyte or tracer, in counts per second
Cx = sample counts in the analyte or the tracer peak
4 = sample count time (s)
Cbx = background counts in the same region of interest (ROI) as for x
tb = background count time (s)
The radiochemical yield and the combined standard uncertainty can be estimated for
each sample, when required, using the following equations:
where:
RY = radiochemical yield of the tracer, expressed as a fraction
Rt = net count rate of the tracer, in counts per second
At = activity of the tracer added to the sample (pCi)
Dt = correction factor for decay of the tracer from its reference date and
time to the midpoint of the counting period
/t = probability of a emission in the defined ROI per decay of the tracer
(Table 17.1)
e = detector efficiency, expressed as a fraction
uc(RY) = 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(e) = standard uncertainly of the detector efficiency
12.1.2. If the critical level concentration (Sc) or the minimum detectable
concentration (MDC) are requested (at an error rate of 5%), they can be
calculated using the following equations:2
negative bias in the estimate of uncertainty and protects against calculating zero uncertainty when zero total counts
are observed for the sample and background.
2 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. The formulations presented here assume an error rate of a = 0.05, ft = 0.05 (with z\-a = 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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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
S =
0.4xp--l +0.677x 1 + ^- +1.645 x \(Rhath + 0.4)x-^-x 1 + ^-
\ f \ f I -ivoao //
V'fe J V lb J \ lb V lb ;
x At x Dt x It
tsxVaxRtxDax!a
MDC =
where:
x Dt x It
tsxVaxRtxDax!a
= 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 noted for each result:
12.2.2.1. Result in scientific notation ± combined standard uncertainty.
12.2.2.2. If solid material was filtered from the solution and analyzed
separately, the results of that analysis should be reported separately
as pCi/L of the original volume from which the solids were filtered if
no other guidance is provided on reporting of results for the solids.
For example:
238U for Sample 12-1-99:
Filtrate Result: 12.8 ± 1.5 pCi/L
Filtered Residue Result: 2.5 ± 0.3 pCi/L
13. Method Performance
13.1. Method validation results are to be reported.
13.2. Expected turnaround time per batch of 14 samples plus QC, assuming
microprecipitations for the whole batch are performed simultaneously using a vacuum
box system:
13.2.1. For an analysis of a 200 mL sample aliquant, sample preparation and
digestion should take -3.5 h.
13.2.2. Purification and separation of the uranium fraction using cartridges and
vacuum box system should take -1.5 h.
13.2.3. The sample test source preparation takes -1 h (longer if wet-ashing is
necessary).
13.2.4. A 1-h counting time should be sufficient to meet the MQOs listed in 9.3 and
9.4, assuming detector efficiency of 0.2-0.3, 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 -6 h after beginning of analysis.
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
14. Pollution Prevention: This 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 uranium.
15. Waste Management
15.1. Types of waste generated per sample analyzed
15.1.1. If calcium phosphate coprecipitation is performed, 100-1000 mL of decanted
solution that is pH neutral is generated.
15.1.2. Approximately 65 mL of acidic waste from loading and rinsing the extraction
column will be generated. The solution may contain unknown quantities of
radionuclides as may be present in the original sample. If presence of other
radionuclides in the sample is suspected, combined effluents should be
collected separately from other rinses to minimize quantity of mixed waste
generated.
15.1.3. Approximately 45 mL of slightly acidic waste, containing 1 mL of HF and ~ 8
mL ethanol are produced in the microprecipitation step.
15.1.4. UTEVA cartridge - ready for appropriate disposal.
15.2. Evaluate all waste streams to ensure that all local, state, and federal disposal
requirements are met.
16. References
16.1. ACW02, Rev. 1.3, "Uranium in Water," Eichrom Technologies, Inc., Lisle, Illinois
(April 2001).
16.2. G-03, V.I "Microprecipitation Source Preparation for Alpha Spectrometry," HASL-
300, 28th Edition, (February 1997).
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. VBS01, "Setup and Operation Instructions for Eichrom's Vacuum Box System
(VBS)," Eichrom Technologies, Inc., Lisle, Illinois (Rev. 1.3, January 30, 2004).
16.5. U.S. Environmental Protection Agency (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. Available
at: www.epa.gov/narel/incident_guides.html.
16.6. 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 at: www.epa.gov/radiation/
marlap/index.html.
16.7. 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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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
17. Tables, Diagrams, Flow Charts, and Validation Data
17.1. Nuclide Decay and Radiation Data
Table 17.1 - Decay and Radiation Data
Nuclide
238U
235U
234U
232U
Half-Life
(Years)
4.468xl09
7.038xl08
2.457xl05
68.9
>,
(s-1)
4.916xlO~18
3.121xlO~17
8.940xlO~14
3.19xlO~10
Abundance
0.79
0.21
0.050
0.042
0.0170
0.0070
0.0210
0.55
0.170
0.7138
0.2842
0.002
0.6815
0.3155
a Energy
(MeV)
4.198
4.151
4.596
4.556
4.502
4.435
4.414
4.398
4.366
4.775
4.722
4.604
5.320
5.263
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
17.2. Ingrowth Curves and Ingrowth Factors
This section intentionally left blank
17.3. Spectrum from a Processed Sample
160-
150-
•
130-
120-
•
100-
90-
70-
60-
.
40-
30-
10-
0 •
IJ
U-238
|
||
i
'
,
i -
i
lu-2!
J
5
J
l'
k
h
e
\f
{
\\
I •
_,\
'in
I
1-2;
\
4
/!
1
J
II
U-23
y
2
3049 3349 3649 3949 4249 4549 4849 5149 5449 5749 6049 6349 6649 6949 7249 7549 7649
Energy (keV)
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
17.4. Decay Scheme: Ingrowth is not generally a large concern with this analysis unless one is
running sequential analysis for uranium and plutonium with 236Pu tracer (due to ingrowth
of 232U tracer) or sequential analyses for uranium and thorium (due to 228Th tracer
ingrowth in the 232U tracer).
P
3.3x1 04 y
231 pa
1.1 d
P
235U
a
7.04x1 0B y
231 Th
23^
a
2.45x105y
a
230Th
li 1
u
6
7h
P
234pa
2381 1
4.47x103
P
24 d
234Th
i n
a
y
-
7.5x104y
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
17.5. Flowchart
Separation Scheme and Timeline for Determination of
U Isotopes in Water Samples
Sample preparation (Step 11.1)
1. Digestion (Step 11.1.5)
or
2. Calcium phosphate coprecipitation
(Step 11.1.4)
3. Add phenolphthalein (Step 11.1.4.3)
(1-2 hours)
T
Preparation of load solution (Step
11.2.1)
1. Dissolve phosphate.
2. Add sulfamate, thiocyanate and
ascorbic acid
(5 min)
T
Set-up of UTEVA cartridge
using vacuum box (Step 11.2.2)
1. Assembly
2. Precondition with 5 ml 3 M HN03
la) ~3 mL/min
Load sample: @ ~1 mL/min
Rinse: 5 mL3M HN03, @ ~3 mL/min
2nd rinse: 5 ml_3M HN03,@~3 mL/min
Additional 30 mL 3M HMO,, rinse for Po-210 if present
(Step 11.2.3)
(~ 25 min)
Discard effluents
I
J
Rinse: 5 mLof9 M HCI
20 mL of 5 M HCI - 0.05 M oxalic acid
(Step 11.2.3.4-11.2.3.5)
Discard
effluents
I
i
Elute U with 15 mL of 1 M HCI collecting eluent
(Step 11.2.3.7)
Discard UTEVA
Column
« I
* J
Transfer eluent to beaker and evaporate
Add drops of HCL and 1 mL H20 to dissolve
Transfer to culture tube w/2 1-mL rinses of 1M HCI.
(Step 11.2.3.8-11.2.3.11)
(15 min)
Microprecipitation
1. Add NdF3 carrier and wait 30 min
2. Filter, dry, mount
(Step 11.3)
(1 hour 15 min)
Discard filtrates and washes
Count sample test source (STS)
for at least one hour
(Step 11.3.19)
(1 hour)
Elapsed Time
1 -2 hours
1-1 V4 hours
1 % hours
11/4 hours
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Isotopic Uranium (238U, 235U, and 234U) in Water: Rapid Method for High-Activity Samples
Appendix
Table Al - Composition of Atlanta Drinking Water Used for this Study
Metals by ICP-AES
Silicon
Aluminum
Barium
Calcium
Iron
Magnesium
Potassium
Sodium
Inorganic Anions
Chloride
Sulfate
Nitrogen, Nitrate (as N)
Carbon Dioxide
Bicarbonate Alkalinity
Carbonate Alkalinity
Radionuclide
Uranium 234, 235, 238
Plutonium 238, 239/240
Americium 24 1
Strontium 90
***
Radium 226
Concentration (mg/L)*
3.18
<0.200
0.0133
9.38
<0.100
<0.500
<0.500
<0.500
12.7
15.6
1.19
23.8
<3.00
Concentration (pCi/L)**
<0.01,<0.01,<0.01
<0.02, <0.02
<0.02
<0.3
0.11 ±0.27
-0.30 ±0.45
Note: Analyses conducted by independent laboratories.
* Values below the reporting level are presented as less than (<) values.
No measurement uncertainty was reported with values greater than the "Reporting
Level."
** Reported values represent the calculated minimum detectable concentration (MDC)
for the radionuclide(s).
*** Two samples analyzed.
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