ASTM D7283-17

Standard Test Method for Alpha and Beta Activity in Water By Liquid Scintillation Counting

SIGNIFICANCE AND USE
5.1 This test method is intended for the measurement of gross alpha- and beta-activity concentrations in the analyses of environmental and drinking waters. For samples submitted to satisfy regulatory or permit requirements, the submitter should assure that this or any other method used is acceptable to the regulator or permit issuer.  
5.2 This test method is also applicable to the direct analysis of gross alpha- and beta-activity concentrations in water when low detection limits are not required. Direct analysis provides a rapid method for determination of gross alpha- and beta-activity concentrations when low detection limits are not required.  
5.3 This test method is not capable of discriminating among alpha emitting radionuclides or among beta emitting radionuclides. Those intending to identify and quantify specific radionuclides should use test methods specific to the radionuclides of interest.  
5.4 This test method may not be cited as a method for the determination of gross alpha- or beta-activity concentrations in a solid/soil matrix or the acid digestate of the same. The use of this test method for such applications brings the potential for serious bias and incomparability of results dependent on the matrix constituents, manner of sample preparation or treatment, or both.
SCOPE
1.1 This test method covers the measurement of gross alpha- and beta- activity concentrations in a homogeneous water sample. It is applicable to alpha emitters with activity concentration levels above 0.11 Bq/L (3 pCi/L) and beta emitters with activity concentration levels above 0.15 Bq/L (4 pCi/L). This test method is not applicable to samples containing radionuclides that are volatile under conditions of the analysis.  
1.2 This test method may also be used for the direct measurement of gross alpha- and beta- activity concentrations in homogeneous water samples with alpha emitter activity concentration levels above 1.8 Bq/L (50 pCi/L) and beta emitter activity concentration levels above 3.7 Bq/L (100 pCi/L).  
1.3 This test method was tested using single-operator tests.2,3 A collaborative study following the U.S. EPA “Protocol for the Evaluation of Alternate Test Procedures for Analyzing Radioactive Contaminants in Drinking Water” was performed. The results of this study are on file at ASTM Headquarters.4  
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to pCi/L that are provided for information only and are not considered standard. An exception is noted in Section 14.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2017
• ICS: 17.240 - Radiation measurements
• Technical Committee: D19 - Water
• Drafting Committee: D19.04 - Methods of Radiochemical Analysis

Relations

• Replaces: ASTM D7283-13 - Standard Test Method for Alpha and Beta Activity in Water By Liquid Scintillation Counting
• Effective Date: 01-Jun-2017
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D7902-20 - Standard Terminology for Radiochemical Analyses
• Effective Date: 01-May-2020
• Refers: ASTM D4448-01(2019) - Standard Guide for Sampling Ground-Water Monitoring Wells
• Effective Date: 01-Feb-2019
• Refers: ASTM D7902-18 - Standard Terminology for Radiochemical Analyses
• Effective Date: 01-Feb-2018
• Refers: ASTM D1890-15(2017) - Standard Test Method for Beta Particle Radioactivity of Water
• Effective Date: 15-Dec-2017
• Refers: ASTM D7902-16 - Standard Terminology for Radiochemical Analyses
• Effective Date: 01-Feb-2016
• Refers: ASTM D1890-15 - Standard Test Method for Beta Particle Radioactivity of Water 
• Effective Date: 01-Jan-2015
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM D7902-14 - Standard Terminology for Radiochemical Analyses
• Effective Date: 15-Jan-2014
• Refers: ASTM D7902-14e1 - Standard Terminology for Radiochemical Analyses
• Effective Date: 15-Jan-2014
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM D4448-01(2013) - Standard Guide for Sampling Ground-Water Monitoring Wells
• Effective Date: 01-Apr-2013
• Refers: ASTM D1890-05(2012) - Standard Test Method for Beta Particle Radioactivity of Water 
• Effective Date: 01-Jun-2012

Overview

ASTM D7283-17 is the Standard Test Method for Alpha and Beta Activity in Water by Liquid Scintillation Counting, developed by ASTM International. This standard outlines procedures for measuring gross alpha and beta radioactivity concentrations in homogeneous water samples using liquid scintillation counting. It is commonly applied in the analysis of environmental and drinking water to assess radiological safety and regulatory compliance. The method is significant for monitoring water quality, especially where radioactive contamination may be present due to natural or anthropogenic sources.

Key Topics

• Measurement Scope:

  • Determines gross alpha and gross beta activity in homogeneous water samples.
  • Applicable to samples meeting minimum activity levels: above 0.11 Bq/L (3 pCi/L) for alpha emitters and above 0.15 Bq/L (4 pCi/L) for beta emitters.
  • Not suitable for samples containing volatile radionuclides or for solid/soil matrices.

• Direct and Evaporative Analysis:

  • Supports both direct analysis and evaporative concentration techniques, depending on detection limits required.
  • Direct analysis facilitates rapid results when high sensitivity is not needed.

• Calibration and Detection:

  • Emphasizes the importance of calibrated instrumentation and proper selection of reference standards for alpha and beta emitters.
  • Does not differentiate individual radionuclides within alpha or beta groups; further analysis is required for radionuclide identification.

• Regulatory Compliance:

  • Clarifies that method selection should always be approved by relevant regulatory or permitting authorities when used for compliance monitoring.

• Limitations and Interferences:

  • Not designed for detecting volatile radionuclides or radionuclides in solid matrices.
  • Caution is required to avoid interferences from quenching, background radioactivity, or sample preparation inconsistencies.

Applications

• Environmental Monitoring:

  • Used in routine surveillance of natural water bodies, groundwater, and effluents to detect changes in radioactive content.
  • Supports environmental impact assessments and ongoing water quality control.

• Drinking Water Analysis:

  • Applied by laboratories and utilities to verify compliance with regulatory standards for radiological safety in drinking water.
  • Enables rapid screening of alpha and beta radioactivity where low detection limits are not required.

• Industrial and Regulatory Compliance:

  • Assists industries subject to discharge permits or environmental regulations to monitor and demonstrate compliance concerning radioactive discharges.
  • Facilitates data generation for permit applications, routine reporting, and incident response.

• Quality Assurance:

  • Can be integrated into laboratory quality management systems for ensuring the accuracy and traceability of radioactive water analysis.

Related Standards

When implementing or referencing ASTM D7283-17, consider its alignment and relationship with these related standards and methods:

• ASTM D1193 – Specification for Reagent Water
• ASTM D3370 – Practices for Sampling Water from Closed Conduits
• ASTM D3856 – Guide for Management Systems in Laboratories Engaged in Analysis of Water
• ASTM D1890 / D1943 – Test Methods for Beta and Alpha Particle Radioactivity of Water
• EPA 900.0 – Gross Alpha and Gross Beta Radioactivity in Drinking Water
• ISO 9696 / ISO 11704 – International standards on measurement of alpha and beta activity concentrations in non-saline water
• Standard Methods 7110C, 8010E – Procedures for measurement of gross radioactivity in water

Practical Value

ASTM D7283-17 provides a reliable and standardized approach for measuring gross alpha and beta radioactive activity in water samples. Its practical value is clear in water quality monitoring, environmental safety assessments, and regulatory compliance. By offering rapid and reproducible methods, this standard supports organizations in protecting public health and meeting legal requirements for radioactive contaminants in water.

For best results, laboratories should ensure correct sample collection, proper use of certified reference standards, and adherence to method limitations and regulatory guidelines.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7283 − 17
Standard Test Method for
Alpha and Beta Activity in Water By Liquid Scintillation
Counting
This standard is issued under the fixed designation D7283; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the measurement of gross
responsibility of the user of this standard to establish appro-
alpha- and beta- activity concentrations in a homogeneous
priate safety and health practices and determine the applica-
water sample. It is applicable to alpha emitters with activity
bility of regulatory limitations prior to use.
concentration levels above 0.11 Bq/L (3 pCi/L) and beta
1.6 This international standard was developed in accor-
emitters with activity concentration levels above 0.15 Bq/L (4
dance with internationally recognized principles on standard-
pCi/L). This test method is not applicable to samples contain-
ization established in the Decision on Principles for the
ing radionuclides that are volatile under conditions of the
Development of International Standards, Guides and Recom-
analysis.
mendations issued by the World Trade Organization Technical
1.2 This test method may also be used for the direct
Barriers to Trade (TBT) Committee.
measurement of gross alpha- and beta- activity concentrations
in homogeneous water samples with alpha emitter activity
2. Referenced Documents
concentration levels above 1.8 Bq/L (50 pCi/L) and beta
2.1 ASTM Standards:
emitter activity concentration levels above 3.7 Bq/L (100
D1129Terminology Relating to Water
pCi/L).
D1125Test Methods for Electrical Conductivity and Resis-
1.3 This test method was tested using single-operator
tivity of Water
2,3
tests. AcollaborativestudyfollowingtheU.S.EPA“Protocol
D1193Specification for Reagent Water
for the Evaluation of Alternate Test Procedures for Analyzing
D1890Test Method for Beta Particle Radioactivity ofWater
Radioactive Contaminants in Drinking Water” was performed.
D1943Test Method for Alpha Particle Radioactivity of
The results of this study are on file at ASTM Headquarters.
Water
1.4 The values stated in SI units are to be regarded as D3370Practices for Sampling Water from Closed Conduits
standard. The values given in parentheses are mathematical D3648Practices for the Measurement of Radioactivity
conversions to pCi/L that are provided for information only D3856Guide for Management Systems in Laboratories
and are not considered standard. An exception is noted in Engaged in Analysis of Water
Section 14. D4448GuideforSamplingGround-WaterMonitoringWells
D5847Practice for Writing Quality Control Specifications
for Standard Test Methods for Water Analysis
1 D6001Guide for Direct-Push Groundwater Sampling for
This test method is under the jurisdiction ofASTM Committee D19 on Water
Environmental Site Characterization
andisthedirectresponsibilityofSubcommitteeD19.04onMethodsofRadiochemi-
cal Analysis.
D7902Terminology for Radiochemical Analyses
Current edition approved June 1, 2017. Published June 2017. Originally
E177Practice for Use of the Terms Precision and Bias in
approved in 2006. Last previous edition approved in 2013 as D7283 – 13. DOI:
ASTM Test Methods
10.1520/D7283-17.
Wong,C.T.,Soliman,V.M.,andPerera,S.K., Journal of Radioanalytical and
Nuclear Chemistry, Vol 264, No. 2, 2005, pp. 357–363.
Ruberu, S.R., Liu, Y.G., and Perera, S.K., Health Physics, Vol 95, No. 4,
October 2008, pp. 397–406. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Supporting data have been filed atASTM International Headquarters and may contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
beobtainedbyrequestingResearchReportRR:D19-1195.ContactASTMCustomer Standards volume information, refer to the standard’s Document Summary page on
Service at [e-mail]. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7283 − 17
E691Practice for Conducting an Interlaboratory Study to location, shielding of the detector, and the electronics; such
Determine the Precision of a Test Method background includes cosmic rays, contaminating radioactivity,
and electronic noise.
2.2 Other Standards and Publications:
3.2.7 figure of merit, n—a numerical quantity based on one
EPA 900.0Gross Alpha and Gross Beta Radioactivity in
or more characteristics of a system or device, representing a
DrinkingWater,from Prescribed Procedures for Measure-
ment of Radioactivity in Drinking Water(EPA-600/4-80- measure of efficiency or effectiveness; figure of merit is
generally calculated as the square of the efficiency divided by
032)
StandardMethods7110C CoprecipitationMethodforGross the background.
Alpha Radioactivity in Drinking Water
3.2.8 gross alpha, n—in the measurement of radioactivity, a
Standard Methods 8010ETable8010: Recommended Com-
semi-quantitative estimate of the combined activity of alpha-
position for Reconstituted Fresh Water
emitting radionuclides in a test sample.
ISO 9696Water Quality—Measurement of Gross Alpha
3.2.9 gross beta, n—in the measurement of radioactivity, a
Activity in Non-saline Water—Thick Source Method
semi-quantitative estimate of the combined activity of beta-
ISO 11704:2010Water Quality—Measurement of GrossAl-
emitting radionuclides in a test sample.
phaandBetaActivityConcentrationinnon-salinewater–
3.2.10 homogeneous water sample, n—water in which the
Liquid Scintillation Counting Method
alpha and beta activity is uniformly dispersed throughout the
volume of water sample and remains so until the measurement
3. Terminology
is completed or until the sample is evaporated or precipitating
3.1 Definitions—For definitions of terms used in this test
reagents are added to the sample.
method,refertoTerminologiesD1129orD7902.Fortermsnot
3.2.11 reagent background, n—in the measurement of ra-
definedinthistestmethodorinTerminologyD1129,reference
dioactivity of water samples, the counting rate observed when
may be made to other published glossaries.
a sample is replaced by mock sample salts or by reagent
3.2 Definitions of Terms Specific to This Standard:
chemicals used for chemical separations that contain no
3.2.1 alpha-to-beta spillover, n—in the measurement of
analyte.
radioactivity,foragivenemittingsource,thatfractionofalpha
3.2.11.1 Discussion—Reagent background varies with the
particles that are misclassified as beta particles by the counter.
reagent chemicals and analytical methods used and may vary
3.2.2 alpha particle detection effıciency, n—in the measure-
with reagents from different manufacturers and from different
ment of radioactivity, for a given emitting source, that fraction
processing lots.
of alpha particles that are identified as alpha particles by the
counter.
4. Summary of Test Method
3.2.3 beta-to-alpha spillover, n—in the measurement of
4.1 Thetestsampleisreducedbyevaporation,transferredto
radioactivity, for a given emitting source, that fraction of beta
ascintillationvialandmixedwithasuitableliquidscintillation
particlesthataremisclassifiedasalphaparticlesbythecounter.
cocktail. Gross alpha- and beta- activity concentrations are
measured simultaneously by liquid scintillation using alpha/
3.2.4 beta energy, maximum, n—themaximumenergyofthe
beta particle energy spectrum produced during beta decay of a beta discrimination. By optimizing the alpha/beta
discriminator, a high efficiency of alpha- and beta- particle
given radionuclide.
detection can be achieved with acceptable misclassification of
3.2.4.1 Discussion—Since a given beta emitter may decay
betaparticlesintothealphamulti-channelanalyzer(MCA)and
to several different nuclear energy levels of the progeny, more
alphaparticlesintothebetaMCA.Thealpha-andbeta-particle
than one maximum energy may be listed for a given radionu-
efficiency and spillover calibrations of the liquid scintillation
clide.
systemaredeterminedbyusingknownactivitiesofestablished
3.2.5 beta particle detection effıciency, n—in the measure-
referencenuclidesintestsourceshavingcocktail-solventratios
ment of radioactivity, for a given emitting source, that fraction
comparable to that of the test samples. Some commonly
of beta particles that are identified as beta particles by the
241 239 230
employed reference standards include Am, Pu, Th,
counter.
234 235 238
natural isotopic abundance uranium ( U, U, and U),for
3.2.6 detector background, n—in the measurement of
90 90 137 137m
gross alpha, and Sr/ Y, and Cs/ Ba for gross beta.
radioactivity, the counting rate resulting from factors other
Results are reported in activity units equivalent along with the
than the radioactivity of the sample and reagents used.
reference radionuclide (for example, Bq/L gross alpha equiv.
3.2.6.1 Discussion—Detector background varies with the 241
Am).
4.2 If the measurement quality objectives (MQOs) do not
require a low detection limit, an aliquant of the sample may be
AvailablefromUnitedStatesEnvironmentalProtectionAgency(EPA),William
mixed directly with a suitable liquid scintillation cocktail for
Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460,
analysis.
http://www.epa.gov.
Available fromAmericanWaterWorksAssociation (AWWA), 6666W. Quincy
Ave., Denver, CO 80235, http://www.awwa.org. 5. Significance and Use
Available from International Organization for Standardization (ISO), ISO
5.1 This test method is intended for the measurement of
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Geneva, Switzerland, http://www.iso.org. gross alpha- and beta-activity concentrations in the analyses of
D7283 − 17
environmental and drinking waters. For samples submitted to counted for gross alpha. Other published methods such as
satisfy regulatory or permit requirements, the submitter should Standard Methods 7110C provide for a shorter delay of 3 h.
assure that this or any other method used is acceptable to the Thus the activity of samples containing Ra will increase
regulator or permit issuer. significantly with time during the first several weeks after
preparation. This delay will result in overestimation of the
5.2 This test method is also applicable to the direct analysis
activity of samples relative to their true Ra concentration.
of gross alpha- and beta-activity concentrations in water when
Thistestmethodadvisesthatanysuchdelayperiodusedbythe
low detection limits are not required. Direct analysis provides
laboratorybebasedontheMQOsinherentintheintendeddata
a rapid method for determination of gross alpha- and beta-
use (see 11.7).
activity concentrations when low detection limits are not
required. 6.5 Radionuclides may be present in the sample in disequi-
librium with their parent radionuclides. Many factors, includ-
5.3 Thistestmethodisnotcapableofdiscriminatingamong
ing differential solubility of radionuclides from the matrix in
alpha emitting radionuclides or among beta emitting radionu-
which the parent radionuclide occurs can cause this disequi-
clides. Those intending to identify and quantify specific radio-
librium.Wheretheseradionuclideshaveahalf-lifeontheorder
nuclides should use test methods specific to the radionuclides
of a few days or shorter, the time elapsed between sampling
of interest.
andthebeginningofsamplecountingwilltendtobiasthefinal
5.4 This test method may not be cited as a method for the
result low. In those cases, the MQOs inherent in the intended
determinationofgrossalpha-orbeta-activityconcentrationsin
datamaydictatethemaximumtimebetweensamplecollection
a solid/soil matrix or the acid digestate of the same.The use of
and the beginning of sample counting. The laboratory should
this test method for such applications brings the potential for
beawareofsuchrequirementsandbepreparedtocomplywith
serious bias and incomparability of results dependent on the
them.
matrix constituents, manner of sample preparation or
6.6 Radionuclides incorporated in volatile compounds are
treatment, or both.
lost during the conduct of this test method. These include
tritium in HTO or C in the carbon dioxide formed during the
6. Interferences
99 2−
addition of acid. The pertechnetate ion ( TcO )isan
6.1 The counting efficiencies and spillover for both the
example of a radionuclide which may be lost through semi-
alpha and beta components are dependent on the energy of the
volatility. The MQOs should address the potential loss of such
alpha- or beta-emitter chosen to determine the calibration
radionuclides and provide direction for their quantification by
coefficient. Biases may occur if the energies of the alpha- or
specific methods.
beta-particle emitting nuclides in the test sample differs sig-
6.7 Whencountinggrossalpha-andbeta-activitybyaliquid
nificantlyfromthoseusedtodeterminetherespectivecounting
scintillation counter using alpha/beta discrimination, some
efficiencies. Best results are obtained when the radionuclide
pulses resulting from alpha particles are misclassified as beta
composition of the sample is known and the calibration
particles and some pulses resulting from beta particles are
radionuclide is selected to match as closely as possible the
misclassified as alpha particles. The “spillover” characteristics
energy of the sample radionuclide.
aredeterminedduringthecalibrationofthespecificinstrument
137 137m
6.2 The use of Cs/ Ba as a calibration standard for
being used.
samples containing radionuclides other than Cs may intro-
6.8 Quenching of the photon output in the liquid scintilla-
duce a low bias in the analytical results unless there is a
tion cocktail reduces detection efficiency and introduces addi-
correction for conversion electron emissions. The conversion
tionaluncertaintyinspillovercorrections.Quenchingiscaused
137m
electrons from the Ba progeny are detected by liquid
by molecular species in the sample and cocktail mixture that
scintillation yielding greater than 100% detection efficiency
137 137m reduce the intermolecular transfer of energy or absorb emitted
for the Cs/ Ba calibration standard.
visible and UV photons prior to detection. This test method
6.3 When using uranium as a calibration standard the
describes the use of an external standard source to compensate
234 235
isotopic abundance of each of the isotopes ( U, U,
for the effects of quenching.
and U) must be known to accurately determine the standard
6.9 The presence of solid particles in the scintillation
activity concentration. Many uranium standards used for mass
cocktail may lead to erroneous results. This test method
measurements are depleted uranium. Natural isotopic abun-
requirescompletedissolutionofthesamplepriortoadditionof
dance uranium and depleted uranium standards contain short-
234 234m the scintillation cocktail.
lived decay progeny ( Th, Pa) which interfere with the
spillovercalibrationunlesstheyareremovedimmediatelyprior 6.10 Thesamplealiquant/scintillationcocktailmixtureratio
to calibration. shouldbewithinthecocktailmanufacturer’srecommendations
to insure a homogeneous mixture. If the sample aliquant/
6.4 Radon is a noble gas, and therefore easily emanates
scintillation cocktail mixture forms two phases, repeat the
from most matrices. If the radon progeny of the uranium
222 220 219 analysis with a different sample aliquant/scintillation cocktail
( Rn), thorium ( Rn), and actinium ( Rn) series emanate
mixture/ratio.
from the sample test source prior to counting, radioactive
equilibrium is disrupted. EPA900.0 recognizes this disruption 6.11 Theexteriorofthevialsmustbefreeofdirt,markings,
by suggesting a delay of 72 h before the prepared sample is and fingerprints.
D7283 − 17
6.12 ‘Dark adapting’ of scintillator solutions is dependent alpha calibration the following radionuclides have found gen-
241 239 230
upon the fluor used in the scintillation cocktail, the instrument, eral usage: Am, Pu, Th, and natural isotopic abun-
234 235 238
and the lighting conditions of the count room. Evaluation of dance uranium ( U, U, and U).
these parameters for the adaptation to the ‘dark’conditions is
8.4 Beta-Emitting Radioactive Standard Solution (;2000
necessary for counting optimization.
Bq/mL in 1M HNO )—traceable to a national standards labo-
ratory (such as NIST or NPL). For gross beta calibration the
6.13 Samples and standards should be counted with the
90 90
following radionuclides have found general usage: Sr/ Y
same instrument operating parameters including temperature.
137 137m
and Cs/ Ba.
For refrigerated instruments, time should be allowed for the
samples to cool to the operating temperature of the instrument.
8.5 Liquid scintillation cocktail—Commercially prepared
Be aware of the potential for phase separation when cooling
LSC cocktail or equivalent.
prepared samples.
8.6 Nitric Acid (sp gr 1.42)—Concentrated nitric acid.
8.7 Nitric Acid (2M)—Mix 128 mL 16M HNO (concen-
7. Apparatus
trated) with water and dilute to 1 L.
7.1 Liquid scintillation vials, approximately 20 mL, of
8.8 Nitric Acid (0.1M)—Mix 6.4 mL 16M HNO (concen-
low-potassium glass are recommended.
trated) with water and dilute to 1 L.
7.2 Hot plate, heating block, drying oven or other appropri-
8.9 Nitromethane (sp gr 1.14)—Other quenching agents
ate device to evaporate the samples.
mayalsobeused.Adjusttheamountofquenchingagentadded
7.3 Liquid scintillation spectrometry system (Liquid Scintil-
to the calibration standards to produce a calibration curve
lation Counter, LSC), coincidence-type with alpha/beta dis-
covering the typical range of quench found in samples.
crimination. A guard detector or other background reduction
electronics or software may be incorporated to reduce the
9. Sampling
instrument background.
9.1 A representative sample must be collected from the
water source and should be large enough so that adequate
8. Reagents and Materials
aliquants can be taken to obtain the required sensitivity. See
8.1 Purity of Reagents—Reagent grade chemicals shall be
Practices D3370 and Guides D4448 and D6001 for guidance
used in all tests. Unless otherwise indicated, it is intended that
on sampling.
all reagents shall conform to the specifications of the Commit-
9.2 Although the container material does not impact the
tee onAnalytical Reagents of theAmerican Chemical Society,
analyte stability, the container choice should generally be
where such specifications are available. Other grades may be
plastic instead of glass to minimize losses due to breakage
used, provided that the reagent is of sufficiently high purity to
during transportation and handling.
permit its use without increasing the background of the
9.3 UnlesscontrarytotheMQOs(forexample,radiocarbon
measurement. Some reagents, even those of high purity, may
or radioiodine analysis is to be performed on the same sample
contain naturally-occurring radionuclides, such as isotopes of
or dissolved gross alpha and beta activity concentrations are
uranium, radium, actinium, thorium, rare earths and potassium
sought), it is recommended that the sample be preserved at the
compounds and/or artificially produced radionuclides.
time of collection by adding enough 2M nitric acid to the
Consequently, when such reagents are used in the analysis of
sample to bring it to pH 2 or less (5 to 10 mLof 2M nitric per
low-radioactivity samples, the activity of the reagents shall be
litre of sample is usually sufficient). Tightly cap the container
determined under analytical conditions that are identical to
and shake well to mix. Confirm the pH with a pH-indicating
those used for the sample. The activity contributed by the
strip or paper.
reagents may be considered to be a component of the back-
9.4 If the dissolved gross alpha and beta activity concentra-
ground and supplied as a correction when calculating the test
sample result. This increased background reduces the sensitiv- tions are sought, the sample must be passed through a
0.45micron filter prior to acid preservation of the sample.
ity of the measurement.
Drinking water samples are not normally filtered prior to
8.2 Purity of Water—Unless otherwise indicated, reference
analysis unless the turbidity is >5 Nephlelometric Turbidity
towatershallbeunderstoodtomeanreagentwaterconforming
Units (NTUs). The use of suction or pressure will speed the
to Specification D1193, Type III.
filtration process.
8.3 Alpha-Emitting Radioactive Standard Solution (;2000
9.5 If samples are collected without preservation, they
Bq/mL in 1M HNO )—traceable to a national standards labo-
should be delivered to the laboratory as quickly as practicable,
ratory (such as the National Institute of Standards and
but no later than 5 days following collection. Upon receipt at
Technology, NIST, in the United States; or the National
the lab, the unpreserved samples may be filtered, as required,
Physics Laboratory, NPL, in the United Kingdom). For gross
andthenacidpreserved.Oncepreservedatthelab,thesamples
should be held for a minimum of 16 h prior to initiation of
sample preparation.
Reagent Chemicals, American Society Specifications, American Chemical
Society,Washington,DC.Forsuggestionsonthetestingofreagentsnotlistedbythe
9.6 Sample analysis should be completed within 180 days
AmericanChemicalSociety,see Analar Standards for Laboratory Chemicals,BDH
fromthetimeofsamplecollection.Samplesmaybeheldforup
Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD. to one year to allow for compositing of quarterly samples.
D7283 − 17
10. Calibration and Standardization 10.4.1 Prepare a scintillation vial containing approximately
200 Bq of an alpha-emitting radionuclide such as Am,
10.1 For gross alpha and gross beta measurement, the
239 230
Pu, or Th in 5 mL of 0.1M HNO plus 15 mL of
scintillation counter must be calibrated to determine the alpha
scintillation cocktail.
particle detection efficiency in the alpha region of interest
10.4.2 Prepare a second scintillation vial containing ap-
(ROI), the alpha particle detection efficiency in the beta ROI,
proximately 200 Bq of a beta- emitting radionuclide, such
the beta particle detection efficiency in the beta ROI, and the
90 90 137 137m
as Sr/ Yor Cs/ Bain5mLof0.1MHNO plus15mL
beta particle detection efficiency in the alpha ROI. For gross
of scintillation cocktail.
alpha calibration the following radionuclides have found gen-
241 239 230
10.4.3 Count the vials for an amount of time required to
eral usage: Am, Pu, Th, and natural isotopic abun-
234 235 238
obtain a relative standard uncertainty of 1% or less in the
dance uranium ( U, U, and U). For gross beta calibra-
count (generally at least 10 000 net counts) at varying
tion the following radionuclides have found general usage:
90 137 137m
discriminator settings. Plot the alpha-to-beta spillover and
Sr/ Yand Cs/ Ba.Thelaboratorymustensurethatthe
beta-to-alpha spillover versus discriminator setting. The point
client is aware of the radionuclides used for the alpha and beta
at which the two curves intersect is the crossover point.
calibrations because the intercomparability of results from
other laboratories will be impacted if they used different
10.5 For each instrument the alpha particle detection effi-
calibration nuclides.
ciency in the alpha ROI, the alpha particle detection efficiency
inthebetaROI,thebetaparticledetectionefficiencyinthebeta
NOTE 1—When using uranium as a calibration standard the isotopic
234 235 238
ROIandthebetaparticledetectionefficiencyinthealphaROI,
abundance of each of the isotopes ( U, U, and U) must be known
toaccuratelydeterminethestandardactivityconcentration.Manyuranium
atvaryinglevelsofquencharedeterminedusingtheoptimized
standards used for mass measurements are depleted uranium. Natural
ROIs and discriminator setting. The alpha and beta radionu-
isotopic abundance uranium and depleted uranium standards contain
clidestandardsusedshouldbetraceabletoanationalstandards
234 234m
short-lived decay progeny ( Th, Pa) which interfere with the
laboratory (such as NIST or NPL).
spillover calibration unless they are removed immediately prior to
calibration. 10.5.1 Forthealphaparticledetectionefficiencyinthealpha
ROIandthealphaparticledetectionefficiencyinthebetaROI,
10.2 Place the instrument into operation according to the
a minimum of five alpha calibration standards are prepared
manufacturer’s instructions. The instrument should be set to
containing varying amounts of quenching agent. For each
acquire counts in the alpha/beta counting mode with discrimi-
calibration standard, aliquot 5.00 mLof 0.1M nitric acid into a
nation of alpha and beta events.
scintillation vial. Spike each of the vials with approximately
10.3 The regions of interest (ROIs) for alpha and beta
200 Bq of the alpha calibration standard. Add 15 mL of
countinginthealphaandbetaMCAsshouldbesettooptimize
scintillationcocktailand0µLto50µLofnitromethanetoeach
the figure of merit (E /B) while ensuring that all radionuclides
of the vials to create a series of quench standards.
of interest are included in each respective region. For an
10.5.2 For the beta particle detection efficiency in the beta
unquenched sample an ROI from 400 keV to 700 keV would
ROIandthebetaparticledetectionefficiencyinthealphaROI,
include most alpha emitting radionuclides of concern. Based
a minimum of five beta calibration standards are prepared
onthequenchcharacteristicsofthesamples,theROIshouldbe
containing varying amounts of quenching agent. For each
adjusted to include the radionuclides of concern, while mini-
calibration standard, aliquot 5.00 mLof 0.1M nitric acid into a
mizing the background count rate. For the sample to cocktail
scintillation vial. Spike each of the vials with approximately
mixture used in this test method (5 mL sample plus 15 mL of
200 Bq of the beta calibration standard. Add 15 mL of
scintillation cocktail) an ROI from 50 keV to 400 keV
scintillationcocktailand0µLto50µLofnitromethanetoeach
generallyincludesthealpha-emittingradionuclidesofconcern.
of the vials to create a series of quench standards.
For beta-emitting radionuclides an ROI from 2 to 2000 keV is
10.5.3 Prepare a background subtraction sample by aliquot-
generally used. A low energy window setting of 2 keV is
ing 5.00 mL of 0.1 M nitric acid into a scintillation vial and
generally sufficient to eliminate luminescence and low energy
adding 15 mL of scintillation cocktail.
noise.
10.5.4 Count both sets of calibration standards and the
10.4 Theoptimumsettingfordiscriminationbetweenalpha-
background subtraction sample using the optimized ROIs and
and beta- particles is the setting where there is equal and
discriminator settings to obtain a relative standard uncertainty
minimum spill of alpha pulses into the beta MCA and beta
of 1% or less in each count (10 000 counts).
pulses into the alpha MCA. This occurs at the crossover point
of the alpha-to-beta spillover and beta-to-alpha spillover
11. Procedure
curves. However, when only the alpha emitter is of interest, a
NOTE 2—To ensure sample integrity, step 11.1, if required, and step
discriminator setting greater than the instrument determined 11.2 should be done promptly after sample receipt at the laboratory if
these actions were not performed at the time of sample collection.
cross-over point may be used, to minimize misclassification of
Samples may be kept at room temperature between receipt and analysis.
betaeventsintothealphaMCAattheexpenseofreducedalpha
detection efficiency. Similarly when only the beta emitter is of 11.1 If filtration of the sample is required by the MQOs and
interest, a discriminator setting below the optimum may be the sample was not filtered at the time of collection, pass a
used.This minimizes the misclassification of alpha events into sample aliquant sufficient for analysis through a 0.45 µm pore
the beta MCA at the expense of reduced beta detection membranefilter.Drinkingwatersnormallyarenotfilteredprior
efficiency. to analysis (unless turbidity is >5NTU).
D7283 − 17
11.2 If the sample was not preserved at the time of should be taken for analysis which will avoid phase separation
collection,addenough2MnitricacidtobringthesampletopH in the subsequent sample preparation.
2 or less (5 to 10 mLof 2M nitric per litre of sample is usually
11.7 TheMQOsinherentintheintendeddatausedetermine
sufficient). Tightly cap the container and shake well to mix.
ifthesamplemustbecountedimmediatelyafterpreparationto
Confirm the pH with pH-indicating strip or paper. Hold the
determine the activity concentration of any short-lived radio-
acidified sample for at least 16 h before starting the analysis.
nuclides (for example, Ra) or if the sample should be held
Samples should be analyzed within 180 days after sample
for a period of time prior to counting to allow for re-
collection, or within one year when compositing quarterly
establishmentofequilibriuminanypresentradionuclidedecay
samples.
chains.
11.3 When steps 11.4 and 11.5 are not performed within
11.8 Prepareabackgroundsubtractionsamplebyaliquoting
four days of step 11.2, recheck the pH of the sample just prior 5.00 mLof 0.1M nitric acid into a scintillation vial and adding
to analysis to ensure that the pH is 2 or less. If the pH is not 2 15 mL of scintillation cocktail.
or less, add sufficient 2M nitric acid to accomplish this, and
11.9 Place the samples and the background subtraction
then hold the sample for at least 16 h prior to the next step.
sampleinacalibratedliquidscintillationcounterandallowfor
dark-adaptation and temperature equilibrium if required.
11.4 Transfer to a clean beaker a measured aliquant of the
water that contains no more than 400 mg of residue mass. The
11.10 Countthesampleintheliquidscintillationcounterfor
amount of dissolved solids in a given sample can be approxi-
a period of time necessary to obtain the required MQOs.
mated by evaporating a small amount (for example, 5 mL) of
12. Calculation
the sample in a tared planchet and weighing to find the net
12.1 Fitting the detection efficiency to the quench relation-
solids. Alternatively the conductance of the unpreserved
ships.
sample can be measured and the amount of dissolved solids
12.1.1 For each of the alpha calibration vials prepared in
approximated (see Test Methods D1125).
10.5.1 through 10.5.4, calculate the alpha particle detection
NOTE 3—The collaborative study for this method indicated a much
efficiencyinthealphaROI,ε ,andthealphaparticledetection
αα
larger variability in the analytical re
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7283 − 13 D7283 − 17
Standard Test Method for
Alpha and Beta Activity in Water By Liquid Scintillation
Counting
This standard is issued under the fixed designation D7283; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the measurement of gross alpha- and beta- activity concentrations in a homogeneous water sample.
It is applicable to alpha emitters with activity concentration levels above 0.11 Bq/L (3 pCi/L) and beta emitters with activity
concentration levels above 0.15 Bq/L (4 pCi/L). This test method is not applicable to samples containing radionuclides that are
volatile under conditions of the analysis.
1.2 This test method may also be used for the direct measurement of gross alpha- and beta- activity concentrations in
homogeneous water samples with alpha emitter activity concentration levels above 1.8 Bq/L (50 pCi/L) and beta emitter activity
concentration levels above 3.7 Bq/L (100 pCi/L).
2,3
1.3 This test method was tested using single-operator tests. A collaborative study following the U.S. EPA “Protocol for the
Evaluation of Alternate Test Procedures for Analyzing Radioactive Contaminants in Drinking Water” was performed. The results
of this study are on file at ASTM Headquarters.
1.4 Standard methods under the jurisdiction of ASTM Committee D19 may be published for a limited time preliminary to the
completion of full collaborative study validation. Such standards are deemed to have met all other D19 qualifying requirements
but have not completed the required validation studies to fully characterize the performance of the Test Method across multiple
laboratories and matrices. Preliminary publication is done to make current technology accessible to users of standards, and to
solicit additional input from the user community.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in thisThe values
given in parentheses are mathematical conversions to pCi/L that are provided for information only and are not considered standard.
An exception is noted in Section 14standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D1125 Test Methods for Electrical Conductivity and Resistivity of Water
D1193 Specification for Reagent Water
D1890 Test Method for Beta Particle Radioactivity of Water
This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemical
Analysis.
Current edition approved Feb. 1, 2013June 1, 2017. Published April 2013June 2017. Originally approved in 2006. Last previous edition approved in 20062013 as D7283
– 06.13. DOI: 10.1520/D7283-13.10.1520/D7283-17.
Wong, C. T., Soliman, V. M., and Perera, S. K., Journal of Radioanalytical and Nuclear Chemistry, Vol 264, No. 2, 2005, pp. 357–363.
Ruberu, S.R., Liu, Y.G., and Perera, S.K., Health Physics, Vol 95, No. 4, October 2008, pp. 397–406.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D19-1195. Contact ASTM Customer
Service at [e-mail].
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7283 − 17
D1943 Test Method for Alpha Particle Radioactivity of Water
D3370 Practices for Sampling Water from Closed Conduits
D3648 Practices for the Measurement of Radioactivity
D3856 Guide for Management Systems in Laboratories Engaged in Analysis of Water
D4448 Guide for Sampling Ground-Water Monitoring Wells
D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis
D6001 Guide for Direct-Push Groundwater Sampling for Environmental Site Characterization
D7902 Terminology for Radiochemical Analyses
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 Other Standards and Publications:
EPA 900.0 Gross Alpha and Gross Beta Radioactivity in Drinking Water, from Prescribed Procedures for Measurement of
Radioactivity in Drinking Water (EPA-600/4-80-032)
Standard Methods 7110C Coprecipitation Method for Gross Alpha Radioactivity in Drinking Water
Standard Methods 8010E Table 8010: Recommended Composition for Reconstituted Fresh Water
ISO 9696 Water Quality—Measurement of Gross Alpha Activity in Non-saline Water—Thick Source Method
ISO 11704:2010 Water Quality—Measurement of Gross Alpha and Beta Activity Concentration in non-saline water – Liquid
Scintillation Counting Method
3. Terminology
3.1 Definitions—For definitions of terms used in this test method, refer to TerminologyTerminologies D1129 or D7902. For
terms not defined in this test method or in Terminology D1129, reference may be made to other published glossaries.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 alpha-to-beta spillover, n—in the measurement of radioactivity, for a given emitting source, that fraction of alpha particles
that are misclassified as beta particles by the counter.
3.2.2 alpha particle detection effıciency, n—in the measurement of radioactivity, for a given emitting source, that fraction of
alpha particles that are identified as alpha particles by the counter.
3.2.3 beta-to-alpha spillover, n—in the measurement of radioactivity, for a given emitting source, that fraction of beta particles
that are misclassified as alpha particles by the counter.
3.2.4 beta energy, maximum, n—the maximum energy of the beta particle energy spectrum produced during beta decay of a
given radionuclide.
Available from United States Environmental Protection Association (EPA), Ariel Rios Agency (EPA), William Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW,
Washington, DC 20460, http://www.epa.gov.
Available from American Water Works Association (AWWA), 6666 W. Quincy Ave., Denver, CO 80235, http://www.awwa.org.
Available from International Organization for Standardization (ISO), 1 rue de Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland, http://www.iso.ch.ISO
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland, http://www.iso.org.
3.2.4.1 Discussion—
Since a given beta emitter may decay to several different nuclear energy levels of the progeny, more than one maximum energy
may be listed for a given radionuclide.
3.2.5 beta particle detection effıciency, n—in the measurement of radioactivity, for a given emitting source, that fraction of beta
particles that are identified as beta particles by the counter.
3.2.6 detector background, n—in the measurement of radioactivity, the counting rate resulting from factors other than the
radioactivity of the sample and reagents used.
3.2.6.1 Discussion—
Detector background varies with the location, shielding of the detector, and the electronics; such background includes cosmic rays,
contaminating radioactivity, and electronic noise.
3.2.7 figure of merit, n—a numerical quantity based on one or more characteristics of a system or device, representing a measure
of efficiency or effectiveness; figure of merit is generally calculated as the square of the efficiency divided by the background.
3.2.8 gross alpha, n—in the measurement of radioactivity, a semi-quantitative estimate of the combined activity of
alpha-emitting radionuclides in a test sample.
D7283 − 17
3.2.9 gross beta, n—in the measurement of radioactivity, a semi-quantitative estimate of the combined activity of beta-emitting
radionuclides in a test sample.
3.2.10 homogeneous water sample, n—water in which the alpha and beta activity is uniformly dispersed throughout the volume
of water sample and remains so until the measurement is completed or until the sample is evaporated or precipitating reagents are
added to the sample.
3.2.11 reagent background, n—in the measurement of radioactivity of water samples, the counting rate observed when a sample
is replaced by mock sample salts or by reagent chemicals used for chemical separations that contain no analyte.
3.2.11.1 Discussion—
Reagent background varies with the reagent chemicals and analytical methods used and may vary with reagents from different
manufacturers and from different processing lots.
4. Summary of Test Method
4.1 The test sample is reduced by evaporation, transferred to a scintillation vial and mixed with a suitable liquid scintillation
cocktail. Gross alpha- and beta- activity concentrations are measured simultaneously by liquid scintillation using alpha/beta
discrimination. By optimizing the alpha/beta discriminator, a high efficiency of alpha- and beta- particle detection can be achieved
with acceptable misclassification of beta particles into the alpha multi-channel analyzer (MCA) and alpha particles into the beta
MCA. The alpha- and beta- particle efficiency and spillover calibrations of the liquid scintillation system are determined by using
known activities of established reference nuclides in test sources having cocktail-solvent ratios comparable to that of the test
241 239 230
samples. Some commonly employed reference standards include Am, Pu, Th, natural isotopic abundance uranium
234 235 238 90 90 137 137m
( U, U, and U), for gross alpha, and Sr/ Y, and Cs/ Ba for gross beta. Results are reported in activity units
equivalent along with the reference radionuclide (for example, Bq/L gross alpha equiv. Am).
4.2 If the measurement quality objectives (MQOs) do not require a low detection limit, an aliquant of the sample may be mixed
directly with a suitable liquid scintillation cocktail for analysis.
5. Significance and Use
5.1 This test method is intended for the measurement of gross alpha- and beta-activity concentrations in the analyses of
environmental and drinking waters. For samples submitted to satisfy regulatory or permit requirements, the submitter should assure
that this or any other method used is acceptable to the regulator or permit issuer.
5.2 This test method is also applicable to the direct analysis of gross alpha- and beta-activity concentrations in water when low
detection limits are not required. Direct analysis provides a rapid method for determination of gross alpha- and beta-activity
concentrations when low detection limits are not required.
5.3 This test method is not capable of discriminating among alpha emitting radionuclides or among beta emitting radionuclides.
Those intending to identify and quantify specific radionuclides should use test methods specific to the radionuclides of interest.
5.4 This test method may not be cited as a method for the determination of gross alpha- or beta-activity concentrations in a
solid/soil matrix or the acid digestate of the same. The use of this test method for such applications brings the potential for serious
bias and incomparability of results dependent on the matrix constituents, manner of sample preparation or treatment, or both.
6. Interferences
6.1 The counting efficiencies and spillover for both the alpha and beta components are dependent on the energy of the alpha-
or beta-emitter chosen to determine the calibration coefficient. Biases may occur if the energies of the alpha- or beta-particle
emitting nuclides in the test sample differs significantly from those used to determine the respective counting efficiencies. Best
results are obtained when the radionuclide composition of the sample is known and the calibration radionuclide is selected to match
as closely as possible the energy of the sample radionuclide.
137 137m 137
6.2 The use of Cs/ Ba as a calibration standard for samples containing radionuclides other than Cs may introduce a low
bias in the analytical results unless there is a correction for conversion electron emissions. The conversion electrons from the
137m 137 137m
Ba progeny are detected by liquid scintillation yielding greater than 100 % detection efficiency for the Cs/ Ba calibration
standard.
234 235 238
6.3 When using uranium as a calibration standard the isotopic abundance of each of the isotopes ( U, U, and U) must
be known to accurately determine the standard activity concentration. Many uranium standards used for mass measurements are
depleted uranium. Natural isotopic abundance uranium and depleted uranium standards contain short-lived decay progeny ( Th,
234m
Pa) which interfere with the spillover calibration unless they are removed immediately prior to calibration.
6.4 Radon is a noble gas, and therefore easily emanates from most matrices. If the radon progeny of the uranium ( Rn),
220 219
thorium ( Rn), and actinium ( Rn) series emanate from the sample test source prior to counting, radioactive equilibrium is
D7283 − 17
disrupted. EPA 900.0 recognizes this disruption by suggesting a delay of 72 h before the prepared sample is counted for gross
alpha. Other published methods such as Standard Methods 7110C provide for a shorter delay of 3 h. Thus the activity of samples
containing Ra will increase significantly with time during the first several weeks after preparation. This delay will result in
overestimation of the activity of samples relative to their true Ra concentration. This test method advises that any such delay
period used by the laboratory be based on the measurement quality objectives MQOs inherent in the intended data use (see 11.7).
6.5 Radionuclides may be present in the sample in disequilibrium with their parent radionuclides. Many factors, including
differential solubility of radionuclides from the matrix in which the parent radionuclide occurs can cause this disequilibrium.
Where these radionuclides have a half-life on the order of a few days or shorter, the time elapsed between sampling and the
beginning of sample counting will tend to bias the final result low. In those cases the measurement quality objectives cases, the
MQOs inherent in the intended data may dictate the maximum time between sample collection and the beginning of sample
counting. The laboratory should be aware of such requirements and be prepared to comply with them.
6.6 Radionuclides incorporated in volatile compounds are lost during the conduct of this test method. These include tritium in
14 99 2−
HTO or C in the carbon dioxide formed during the addition of acid. The pertechnetate ion (TcO( TcO ) is an example of a
radionuclide which may be lost through semi-volatility. The Measurement Quality Objectives MQOs should address the potential
loss of such radionuclides and provide direction for their quantification by specific methods.
6.7 When counting gross alpha- and beta-activity by a liquid scintillation counter using alpha/beta discrimination, some pulses
resulting from alpha particles are misclassified as beta particles and some pulses resulting from beta particles are misclassified as
alpha particles. The “spillover” characteristics are determined during the calibration of the specific instrument being used.
6.8 Quenching of the photon output in the liquid scintillation cocktail reduces detection efficiency and introduces additional
uncertainty in spillover corrections. Quenching is caused by molecular species in the sample and cocktail mixture that reduce the
intermolecular transfer of energy or absorb emitted visible and UV photons prior to detection. This test method describes the use
of an external standard source to compensate for the effects of quenching.
6.9 The presence of solid particles in the scintillation cocktail may lead to erroneous results. This test method requires complete
dissolution of the sample prior to addition of the scintillation cocktail.
6.10 The sample aliquant/scintillation cocktail mixture ratio should be within the cocktail manufacturer’s recommendations to
insure a homogeneous mixture. If the sample aliquant/scintillation cocktail mixture forms two phases, repeat the analysis with a
different sample aliquant/scintillation cocktail mixture/ratio.
6.11 The exterior of the vials must be free of dirt, markings, and fingerprints.
6.12 ‘Dark adapting’ of scintillator solutions is dependent upon the fluor, the instrument fluor used in the scintillation cocktail,
the instrument, and the lighting conditions of the count room. Evaluation of these parameters for the adaptation to the ‘dark’
conditions is necessary for counting optimization.
6.13 Samples and standards should be counted with the same instrument operating parameters including temperature. For
refrigerated instruments, time should be allowed for the samples to cool to the operating temperature of the instrument. Be aware
of the potential for phase separation when cooling prepared samples.
7. Apparatus
7.1 Liquid Scintillationscintillation vials, approximately 20 mL, of low-potassium glass are recommended.
7.2 Electric hot plate. Hot plate, heating block, drying oven or other appropriate device to evaporate the samples.
7.3 Glassware.
7.4 Transfer pipettes.
7.3 Liquid scintillation counting system, spectrometry system (Liquid Scintillation Counter, LSC), coincidence-type with
alpha/beta discrimination. A guard detector or other background reduction electronics or software may be incorporated to reduce
the instrument background.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided that the reagent is of sufficiently high purity to permit its
use without increasing the background of the measurement. Some reagents, even those of high purity, may contain
naturally-occurring radionuclides, such as isotopes of uranium, radium, actinium, thorium, rare earths and potassium compounds
Reagent Chemicals, American Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American
Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S.
Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
D7283 − 17
and/or artificially produced radionuclides. Consequently, when such reagents are used in the analysis of low-radioactivity samples,
the activity of the reagents shall be determined under analytical conditions that are identical to those used for the sample. The
activity contributed by the reagents may be considered to be a component of the background and supplied as a correction when
calculating the test sample result. This increased background reduces the sensitivity of the measurement.
8.2 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to
Specification D1193, Type III.
8.3 Alpha-Emitting Radioactive Standard Solution (;2000 Bq/mL in 1M HNO )—traceable to a national standards laboratory
(such as the National Institute of Standards and Technology, NIST, in the USA; United States; or the National Physics Laboratory,
NPL, in the UK). United Kingdom). For gross alpha calibration the following radionuclides have found general usage: Am,
239 230 234 235 238
Pu, Th, and natural isotopic abundance uranium ( U, U, and U).
8.4 Beta-Emitting Radioactive Standard Solution (;2000 Bq/mL in 1M HNO )—traceable to a national standards laboratory
90 90
(such as NIST or NPL). For gross beta calibration the following radionuclides have found general usage: Sr/ Y and
137 137m
Cs/ Ba.
8.5 Liquid scintillation cocktail—Commercially prepared LSC cocktail or equivalent.
8.6 Nitric Acid (sp gr 1.42)—Concentrated nitric acid.
8.7 Nitric Acid (2M)—Mix 128 mL 16M HNO (concentrated) with water and dilute to 1 L.
8.8 Nitric Acid (0.1M)—Mix 6.4 mL 16M HNO (concentrated) with water and dilute to 1 L.
8.9 Nitromethane (sp gr 1.14)—Other quenching agents may also be used. Adjust the amount of quenching agent added to the
calibration standards to produce a calibration curve covering the typical range of quench found in samples.
9. Sampling
9.1 A representative sample must be collected from the water source and should be large enough so that adequate aliquants can
be taken to obtain the required sensitivity. See Practices D3370 and Guides D4448 and D6001 for guidance on sampling.
9.2 Although the container material does not impact the analyte stability, the container choice should generally be plastic instead
of glass to minimize losses due to breakage during transportation and handling.
9.3 Unless contrary to the measurement quality objectives MQOs (for example, radiocarbon or radioiodine analysis is to be
performed on the same sample or dissolved gross alpha and beta activity concentrations are sought), it is recommended that the
sample be preserved at the time of collection by adding enough 2M nitric acid to the sample to bring it to pH 2 or less (5 to 10
mL of 2M nitric per litre of sample is usually sufficient). Tightly cap the container and shake well to mix. Confirm the pH with
a pH-indicating strip or paper.
9.4 If the dissolved gross alpha and beta activity concentrations are sought, the sample must be passed through a 0.45 micron
filter prior to acid preservation of the sample. Drinking water samples are not normally filtered prior to analysis unless the turbidity
is >5 NTU. Nephlelometric Turbidity Units (NTUs). The use of suction or pressure will speed the filtration process.
9.5 If samples are collected without preservation, they should be delivered to the laboratory as quickly as practicable, but no
later than 5 days following collection. Upon receipt at the lab, the unpreserved samples may be filtered, as required, and then acid
preserved. Once preserved at the lab, the samples should be held for a minimum of 16 h prior to initiation of sample preparation.
9.6 Sample analysis should be completed within 180 days from the time of sample collection. Samples may be held for up to
one year to allow for compositing of quarterly samples.
10. Calibration and Standardization
10.1 For gross alpha and gross beta measurement, the scintillation counter must be calibrated to determine the alpha particle
detection efficiency in the alpha region of interest (ROI), the alpha particle detection efficiency in the beta ROI, the beta particle
detection efficiency in the beta ROI, and the beta particle detection efficiency in the alpha ROI. For gross alpha calibration the
241 239 230 234 235
following radionuclides have found general usage: Am, Pu, Th, and natural isotopic abundance uranium ( U, U, and
238 90 90 137 137m
U). For gross beta calibration the following radionuclides have found general usage: Sr/ Y and Cs/ Ba. The laboratory
must ensure that the client is aware of the radionuclides used for the alpha and beta calibrations because the intercomparability
of results from other laboratories will be impacted if they used different calibration nuclides.
234 235 238
NOTE 1—When using uranium as a calibration standard the isotopic abundance of each of the isotopes ( U, U, and U) must be known to
accurately determine the standard activity concentration. Many uranium standards used for mass measurements are depleted uranium. Natural isotopic
234 234m
abundance uranium and depleted uranium standards contain short-lived decay progeny ( Th, Pa) which interfere with the spillover calibration unless
they are removed immediately prior to calibration.
10.2 Place the instrument into operation according to the manufacturer’s instructions. The instrument should be set to acquire
counts in the alpha/beta counting mode with discrimination of alpha and beta events.
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10.3 The regions of interest (ROIs) for alpha and beta counting in the alpha and beta MCAs should be set to optimize the figure
of merit (E /B) while ensuring that all radionuclides of interest are included in each respective region. For an unquenched sample
an ROI from 400 keV to 700 keV would include most alpha emitting radionuclides of concern. Based on the quench characteristics
of the samples, the ROI should be adjusted to include the radionuclides of concern, while minimizing the background count rate.
For the sample to cocktail mixture used in this test method (5 mL sample plus 15 mL of scintillation cocktail) an ROI from 50
keV to 400 keV generally includes the alpha-emitting radionuclides of concern. For beta-emitting radionuclides an ROI from 02
to 2000 keV is generally used. A low energy window setting of 2 keV is generally sufficient to eliminate luminescence and low
energy noise.
10.4 The optimum setting for discrimination between alpha- and beta- particles is the setting where there is equal and minimum
spill of alpha pulses into the beta MCA and beta pulses into the alpha MCA. This occurs at the crossover point of the alpha-to-beta
spillover and beta-to-alpha spillover curves. However, when only the alpha emitter is of interest, a discriminator setting greater
than the instrument determined cross-over point may be used, to minimize misclassification of beta events into the alpha MCA at
the expense of reduced alpha detection efficiency. Similarly when only the beta emitter is of interest, a discriminator setting below
the optimum may be used. This minimizes the misclassification of alpha events into the beta MCA at the expense of reduced beta
detection efficiency.
241 239
10.4.1 Prepare a scintillation vial containing approximately 200 Bq of an alpha-emitting radionuclide such as Am, Pu, or
Th in 5 mL of 0.1M HNO plus 15 mL of scintillation cocktail.
90 90
10.4.2 Prepare a second scintillation vial containing approximately 200 Bq of a beta- emitting radionuclide, such as Sr/ Y
137 137m
or Cs/ Ba in 5 mL of 0.1M HNO plus 15 mL of scintillation cocktail.
10.4.3 Count the vials for an amount of time required to obtain a relative standard uncertainty of 1 % or less in the count
(generally at least 10 000 net counts) at varying discriminator settings. Plot the alpha-to-beta spillover and beta-to-alpha spillover
versus discriminator setting. The point at which the two curves intersect is the crossover point.
10.5 For each instrument the alpha particle detection efficiency in the alpha ROI, the alpha particle detection efficiency in the
beta ROI, the beta particle detection efficiency in the beta ROI and the beta particle detection efficiency in the alpha ROI, at varying
levels of quench are determined using the optimized ROIs and discriminator setting. The alpha and beta radionuclide standards
used should be traceable to a national standards laboratory (such as NIST or NPL).
10.5.1 For the alpha particle detection efficiency in the alpha ROI and the alpha particle detection efficiency in the beta ROI,
a minimum of five alpha calibration standards are prepared containing varying amounts of quenching agent. For each calibration
standard, aliquot 5.00 mL of 0.1M nitric acid into a scintillation vial. Spike each of the vials with approximately 200 Bq of the
alpha calibration standard. Add 15 mL of scintillation cocktail and 0 μL to 50 μL of nitromethane to each of the vials to create a
series of quench standards.
10.5.2 For the beta particle detection efficiency in the beta ROI and the beta particle detection efficiency in the alpha ROI, a
minimum of five beta calibration standards are prepared containing varying amounts of quenching agent. For each calibration
standard, aliquot 5.00 mL of 0.1M nitric acid into a scintillation vial. Spike each of the vials with approximately 200 Bq of the
beta calibration standard. Add 15 mL of scintillation cocktail and 0 μL to 50 μL of nitromethane to each of the vials to create a
series of quench standards.
10.5.3 Prepare a background subtraction sample by aliquoting 5.00 mL of 0.1 M nitric acid into a scintillation vial and adding
15 mL of scintillation cocktail.
10.5.4 Count both sets of calibration standards and the background subtraction sample using the optimized ROIs and
discriminator settings to obtain a relative standard uncertainty of 1 % or less in each count (10 000 counts).
11. Procedure
NOTE 2—To ensure sample integrity, step 11.1, if required, and step 11.2 should be done promptly after sample receipt at the laboratory if these actions
were not performed at the time of sample collection. Samples may be kept at room temperature between receipt and analysis.
11.1 If filtration of the sample is required by the measurement quality objectives MQOs and the sample was not filtered at the
time of collection, pass a sample aliquant sufficient for analysis through a 0.45 μm pore membrane filter. Drinking waters normally
are not filtered prior to analysis (unless turbidity is >5 NTU).
11.2 If the sample was not preserved at the time of collection, add enough 2M nitric acid to bring the sample to pH 2 or less
(5 to 10 mL of 2M nitric per litre of sample is usually sufficient). Tightly cap the container and shake well to mix. Confirm the
pH with pH-indicating strip or paper. Hold the acidified sample for at least 16 h before starting the analysis. Samples should be
analyzed within 180 days after sample collection, or within one year when compositing quarterly samples.
11.3 When steps 11.4 and 11.5 are not performed within four days of step 11.2, recheck the pH of the sample just prior to
analysis to ensure that the pH is 2 or less. If the pH is not 2 or less, add sufficient 2M nitric acid to accomplish this, and then hold
the sample for at least 16 h prior to the next step.
11.4 Transfer to a clean beaker a measured aliquant of the water that contains no more than 400 mg of residue mass. The amount
of dissolved solids in a given sample can be approximated by evaporating a small amount (for example, 5 mL) of the sample in
D7283 − 17
a tared planchet and weighing to find the net solids. Alternatively the conductance of the unpreserved sample can be measured and
the amount of dissolved solids approximated (see Test Methods D1125).
NOTE 3—The collaborative study for this method indicated a much larger variability in the analytical results for spiked deionized water samples.
Addition of approximately 60 mg of the Alternative Test Procedure (ATP) matrix (Appendix X2) used in the collaborative study improved the precision
of the measurements.
NOTE 4—The goal is to use a sufficient aliquot of the sample to meet the MQOs and to maintain a homogeneous mixture when the concentrated sample
is mixed with the scintillation cocktail. An in-homogenous mixture is evidenced by the presence of an emulsion or separate layers. During method
development and robustness testing several possible causes for an in-homogeneous mixture were observed including: (1) dissolved solids greatly in excess
of 400 mg/sample; (2) acid concentrations greatly exceeding 0.1 M HNO ; and (3) refrigeration of the sample/scintillation cocktail mixture. The dissolved
solids are controlled by the sample aliquot size. The acid concentration is controlled by carefully drying the sample to ensure any excess acid from sample
preservation is removed without causing loss of the sample through spattering or creating an insoluble solid by over-heating. This may be effected by
carefully controlling the drying temperature (for example, monitoring the hot plate temperature, using a heating block or drying oven). Counting of the
samples in a refrigerated liquid scintillation counter may cause the formation of a gel (opaque sample with no phase separation). Formation of a gel does
not necessarily compromise the analytical results. The ruggedness of the implementation of this method using typical laboratory samples should be
verified under the conditions used.
11.5 Evaporate the sample aliquant to approximately 4 to 5 mL. Quantitatively transfer to a tared glass scintillation vial using
0.1M HNO . Slowly evaporate to near dryness. Adjust heat carefully to avoid spattering or boiling.
NOTE 3—When evaporating the sample aliquant it is important to remove all remaining HNO . A non-homogeneous mixture (evidenced by the presence
of an emulsion or separate layers) occurs in the scintillation vial if the acid concentration greatly exceeds 0.1M HNO .
11.6 Add 5 mL of 0.1M HNO , loosely cap the vial and warm gently to dissolve the solids. Do not allow the sample to
evaporate. After the sample has cooled to room temperature, add 15 mL of scintillation cocktail and mix thoroughly. The resultant
sample should be a clear homogeneous solution with no evidence of phase separation as evidenced by the presence of an emulsion
or separate layers. There should be no solid residue in the vial. If phase separation occurs, or there is solid residue in the vial, a
significantly smaller sample aliquant should be taken for analysis which will avoid phase separation in the subsequent sample
preparation.
11.7 The measurement quality objectives MQOs inherent in the intended data use determine if the sample must be counted
immediately after preparation to determine the activity concentration of any short-lived radionuclides (for example, Ra) or if
the sample should be held for a period of time prior to counting to allow for re-establishment of equilibrium in any present
radionuclide decay chains.
11.8 Prepare a background subtraction sample by aliquoting 5.00 mL of 0.1M nitric acid into a scintillation vial and adding 15
mL of scintillation cocktail.
11.9 Place the samples and the background subtraction sample in a calibrated liquid scintillation counter and allow for
dark-adaptation and temperature equilibrium if required.
11.10 Count the sample in the liquid scintillation counter for a period of time necessary to obtain the required measurement
quality objectives (MQOs).MQOs.
12. Calculation
12.1 Fitting the detection efficiency to the quench relationships.
12.1.1 For each of the alpha calibration vials prepared in 10.5.1 through 10.5.4, calculate the alpha particle detection efficiency
in the alpha ROI, ε , and the alpha particle detection efficiency in the beta ROI, ε , using the following equations:
αα αβ
R 2 R
αα αb
ϵ 5 (1)
αα
c 3V
α sα
R 2 R
αβ βb
ϵ 5
αβ
c 3V
α sα
R 2 R
αα αb
ε 5 (1)
αα
c 3V
α sα
R 2 R
αβ βb
ε 5
αβ
c 3V
α sα
where:
ε = alpha particle detection efficiency in the alpha ROI,
αα
ε = alpha particle detection efficiency in the beta ROI,
αβ
R = count rate of the alpha standard aliquant in counts per second in the alpha ROI,
αα
R = count rate of the alpha standard aliquant in counts per second in the beta ROI,
αβ
R = count rate of the background subtraction sample in counts per second in the alpha ROI,
αb
R = count rate of the background subtraction sample in counts per second in the beta ROI,
βb
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c = activity concentration of the reference alpha standard in becquerels per millilitre (Bq/mL), and
α
V = volume of the reference alpha standard added to the vial in millilitres (mL).
sα
12.1.2 For each of the beta calibration vials prepared in 10.5.1 through 10.5.4, calculate the beta particle detection efficiency
in the beta ROI, ε , and the beta particle detection efficiency in the alpha ROI, ε , using the following equations:
ββ βα
R 2 R
ββ βb
ϵ 5 (2)
ββ
c 3V
β sβ
R 2 R
βα αb
ϵ 5
βα
c 3V
β sβ
R 2 R
ββ βb
ε 5 (2)
ββ
c 3V
β sβ
R 2 R
βα αb
ε 5
βα
c 3V
β sβ
where:
ε = beta particle detection efficiency in the beta ROI,
ββ
ε = beta particle detection efficiency in the alpha ROI,
βα
R = count rate of the beta standard aliquant in counts per second in the beta ROI,
ββ
R = count rate of the beta standard aliquant in counts per second in the alpha ROI,
βα
R = count rate of the background subtraction sample in counts per second in the alpha ROI,
αb
R = count rate of the background subtraction sample in counts per second in the beta ROI,
βb
c = activity concentration of the reference beta standard in becquerels per millilitre (Bq/mL), and
β
V = volume of the reference beta standard added to the vial in millilitres (mL).
sβ
12.1.3 Use least-squares regression to fit curves to the four series of data points obtained in steps 12.1.1 and 12.1.2, where the
abscissa for each point is the quench indicating parameter and the ordinate is the detection efficiency as calculated by Eq 1 or Eq
2. Whatever mathematical model is chosen for each curve, the curve should be continuous and smooth over the working range of
quench indicating parameter. A quadratic polynomial may be an adequate model for this purpose.
12.1.4 Regression provides the parameters for each curve in the form of a solution vector. It also provides the solution’s
variance-covariance matrix, whose elements are the variances and covariances of the parameters.
12.1.5 At any value of the quench indicating parameter, the two detection efficiencies for alpha particles, ε and ε , are
αα αβ
correlated because of the uncertainty of the alpha activity concentration of each calibration source. Similarly the two detection
efficiencies for beta particles, ε and ε , are correlated because of the uncertainty of the beta activity concentration of each
ββ βα
calibration source. However, the effects of these correlations on the overall measurement uncertainty are considered to be
negligible.
12.2 Determination of the detection efficiencies from the efficiency-to-quench relationships.
12.2.1 From the sample quench indicating parameter, determine the alpha detection efficiency in the alpha ROI, ε , the alpha
αα
detection efficiency in the beta ROI, ε , the beta detection efficiency in the beta ROI, ε , and the beta detection efficiency in the
αβ ββ
alpha ROI, ε .
βα
12.3 Determination of the uncertainties of the detection efficiencies.
12.3.1 Equations for the uncertainties of the four detection efficiencies, ε , ε , ε , and ε , depend on the mathematical model
αα αβ ββ βα
chosen for each detection efficiency curve. In general, the uncertainty for a detection efficiency calculated from a multi-parameter
calibration curve includes not only an uncertainty component for each of the parameters but also additional terms that account for
correlations between the parameters. The variances (that is, squared uncertainties) and covariances of the curve parameters may
be obtained from the variance-covariance matrix described in step 12.1.4.
12.4 Determination of the spillover factors.
12.4.1 The alpha-to-beta spillover factor and the variance of the alpha-to-beta spillover factor can be calculated as follows:
ϵ
αβ
X 5 (3)
α
ϵ
αα
2 2
u ϵ u ϵ
~ ! ~ !
αβ αα
2 2
u ~X !5 X 1
S 2 2 D
α α
ϵ ϵ
αβ αα
ε
αβ
X 5 (3)
α
ε
αα
2 2
u ~ε ! u ~ε !
αβ αα
2 2
u X 5 X 1
~ ! S D
α α 2 2
ε ε
αβ αα
D7283 − 17
where:
X = alpha-to-beta spillover factor,
α
ε = alpha particle detection efficiency in the alpha ROI (a function of the quench parameter),
αα
ε = alpha particle detection efficiency in the beta ROI (a function of the quench parameter),
αβ
u(X ) = standard uncertainty of the alpha spillover factor,
α
u(ε )) = standard uncertainty of the alpha particle detection efficiency in the alpha ROI, and
αα
u(ε )) = standard uncertainty of the alpha particle detection efficiency in the alpha ROI, and
αα
u(ε ) = standard uncertainty of the alpha particle detection efficiency in the beta ROI.
αβ
u(ε ) = standard uncertainty of the alpha particle detection efficiency in the beta ROI.
αβ
12.4.2 The beta-to-alpha spillover factor and the variance of the beta-to-alpha spillover factor can be calculated as follows:
ϵ
βα
X 5 (4)
β
ϵ
ββ
2 2
u ϵ u ϵ
~ ! ~ !
βα ββ
2 2
u ~X !5 X 1
S D
β β 2 2
ϵ ϵ
βα ββ
ε
βα
X 5 (4)
β
ε
ββ
2 2
u ~ε ! u ~ε !
βα ββ
2 2
u ~X !5 X 1
S 2 2 D
β β
ε ε
βα ββ
where:
X = beta-to-alpha spillover factor,
β
ε = beta particle detection efficiency in the beta ROI (a function of the quench parameter),
ββ
ε = beta particle detection efficiency in the alpha ROI (a function of the quench parameter),
βα
u(X ) = standard uncertainty of the beta spillover factor,
β
u(ε )) = standard uncertainty of the beta particle detection efficiency in the beta ROI, and
αα
u(ε )) = standard uncertainty of the beta particle detection efficiency in the beta ROI, and
αα
u(ε ) = standard uncertainty of the beta particle detection efficiency in the alpha ROI.
αβ
u(ε ) = standard uncertainty of the beta particle detection efficiency in the alpha ROI.
αβ
12.5 The net count rates and the standard uncertainties of the net count rates in the alpha ROI and beta ROI are calculated as
follows:
R 5 R 2 R (5)
α αα αb
R R
αα αb
u R 5 1
~ ! Œ
α
t t
s b
R 5 R 2 R
β ββ βb
R R
ββ βb
u~R !5Π1
β
t t
s b
where:
R = net count rate of the sample aliquant in counts per second in the alpha ROI,
α
R = count rate of the sample aliquant in counts per second in the alpha ROI,
αα
R = count rate of the background subtraction sample in counts per second in the alpha ROI,
αb
R = net count rate of the sample aliquant in counts per second in the beta ROI,
β
R = count rate of the sample aliquant in counts per second in the beta ROI,
ββ
R = count rate of the background subtraction sample in counts per second in the beta ROI,
βb
t = count time for the sample in seconds, and
s
t = count time for the background subtraction sample in seconds.
b
12.6 The corrected alpha and beta count rates (net alpha and beta count rates corrected for spillover) can be calculated as
follows:
R 2 R X
α β β
'
R 5 (6)
α
12 X X
α β
R 2 R X
β α α
'
R 5
β
12 X X
α β
D7283 − 17
where:
'
R = alpha count rate corrected for spillover, and
α
'
R = beta count rate corrected for spillover.
β
R' = alpha count rate corrected for spillover, and
α
R' = beta count rate corrected for spillover.
β
12.7 The combined standard uncertainties of the corrected count rates are calculated as follows:
2 2 2 ’2 2 2 ’2 2
u ~R !1X u ~R !1R X u ~X !1R u ~X !
α β β α β α β β
'
u ~R !5Π(7)
c α
12 X X
α β
2 2 2 '2 2 2 '2 2
u ~R !1X u ~R !1R X u ~X !1R u ~X !
β α α β α β α α
'
u R 5
~ ! Œ
c β
12 X X
α β
12.8 The sample gross alpha activity concentration and the combined standard uncertainty of the gross alpha activity
concentration can be calculated from the following:
'
R
α
AC 5 (8)
α
ϵ 3V
αα
2 ' 2 2
u ~R ! u ~V! 11X X u ~ϵ !
c α α β αα
u AC 5 1AC 3 1 3
~ ! Œ
2 2 S 2 2 D
c α α
ϵ 3V V 12 X X ϵ
αα α β αα
'
R
α
AC 5 (8)
α
ε 3V
αα
2 ' 2 2
u R u V 11X X u ε
~ ! ~ ! ~ !
c α α β αα
u ~AC !5Π1AC 3 1 3
S D
c α 2 2 α 2 2
ε 3V V 12 X X ε
αα α β αα
where:
AC = sample gross alpha activity concentration in becquerels per litre (Bq/L),
α
V = sample aliquot volume in litres (L), and
u (AC ) = combined standard uncertainty of the sample gross alpha activity concentration in becquerels per litre (Bq/L).
c α
(other symbols are defined as above)
12.9 The sample gross beta activity concentration and combined standard uncertainty of the gross beta activity concentration
can be calculated from the following:
'
R
β
AC 5 (9)
β
ε 3V
ββ
2 ' 2 2
u R u V 11X X u ϵ
~ ! ~ ! ~ !
c β α β ββ
u AC 5 1AC 3 1 3
~ ! ΠS D
c β 2 2 β 2 2
ε 3V V 12 X X ϵ
ββ
...