ASTM C1307-02(2008)
(Test Method)Standard Test Method for Plutonium Assay by Plutonium (III) Diode Array Spectrophotometry
Standard Test Method for Plutonium Assay by Plutonium (III) Diode Array Spectrophotometry
SIGNIFICANCE AND USE
p>This test method is designed to determine whether a given material meets the purchaser's specification for plutonium content.
SCOPE
1.1 This test method describes the determination of total plutonium as plutonium(III) in nitrate and chloride solutions. The technique is applicable to solutions of plutonium dioxide powders and pellets (Test Methods C 697), nuclear grade mixed oxides (Test Methods C 698), plutonium metal (Test Methods C 758), and plutonium nitrate solutions (Test Methods C 759). Solid samples are dissolved using the appropriate dissolution techniques described in Practice C 1168. The use of this technique for other plutonium-bearing materials has been reported (1-5), but final determination of applicability must be made by the user. The applicable concentration range for plutonium sample solutions is 10–200 g Pu/L.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C1307 − 02 (Reapproved2008)
Standard Test Method for
Plutonium Assay by Plutonium (III) Diode Array
Spectrophotometry
This standard is issued under the fixed designation C1307; 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 Spectrochemical Analysis of Nuclear-Grade Mixed Ox-
ides ((U, Pu)O )
1.1 This test method describes the determination of total
C757Specification for Nuclear-Grade Plutonium Dioxide
plutonium as plutonium(III) in nitrate and chloride solutions.
Powder, Sinterable
The technique is applicable to solutions of plutonium dioxide
C758Test Methods for Chemical, Mass Spectrometric,
powdersandpellets(TestMethodsC697),nucleargrademixed
Spectrochemical,Nuclear,andRadiochemicalAnalysisof
oxides (Test Methods C698), plutonium metal (Test Methods
Nuclear-Grade Plutonium Metal
C758), and plutonium nitrate solutions (Test Methods C759).
C759Test Methods for Chemical, Mass Spectrometric,
Solid samples are dissolved using the appropriate dissolution
Spectrochemical,Nuclear,andRadiochemicalAnalysisof
techniques described in Practice C1168. The use of this
Nuclear-Grade Plutonium Nitrate Solutions
technique for other plutonium-bearing materials has been
C833Specification for Sintered (Uranium-Plutonium) Diox-
reported (1-5), but final determination of applicability must be
ide Pellets
made by the user. The applicable concentration range for
C1168PracticeforPreparationandDissolutionofPlutonium
plutonium sample solutions is 10–200 g Pu/L.
Materials for Analysis
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3. Summary of Method
standard.
3.1 In a diode array spectrophotometric measurement, as in
1.3 This standard does not purport to address all of the
aconventionalspectrophotometricmeasurement,thesubstance
safety concerns, if any, associated with its use. It is the
being determined absorbs light at frequencies characteristic of
responsibility of the user of this standard to establish appro-
that substance. The amount of light absorbed at each wave-
priate safety and health practices and determine the applica-
length is directly proportional to the concentration of the
bility of regulatory limitations prior to use.
speciesofinterest.Theabsorptionisafunctionoftheoxidation
state and the complexation obtained in the solution matrix
2. Referenced Documents
selected for measurement. Beer’s Law permits quantifying the
2.1 ASTM Standards: species of interest relative to a traceable standard when both
C697Test Methods for Chemical, Mass Spectrometric, and
solutionsaremeasuredunderthesameconditions.Thearrayof
Spectrochemical Analysis of Nuclear-Grade Plutonium photosensitive diodes permits the (virtually) simultaneous
Dioxide Powders and Pellets
collection of spectral information over the entire range of the
C698Test Methods for Chemical, Mass Spectrometric, and instrument, for example, 190–820 nm (or any selected portion
oftherange).Anentireabsorptionspectrumcanbeobtainedin
0.1 s; however, optimum precision is obtained from multiple
spectra collected over a 4-s period.
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
3.2 Reduction to plutonium(III) is accomplished by the
Test.
addition of a measured quantity of reductant solution to the
CurrenteditionapprovedJune1,2008.PublishedJuly2008.Originallyapproved
in 1995. Last previous edition approved in 2002 as C1307–02. DOI: 10.1520/ sample aliquant.
C1307-02R08.
3.2.1 For nitrate solutions, ferrous sulfamate is the recom-
Forsolidsamples,selectthesamplesizeanddissolvedsolutionweighttoyield
mended reductant. Aliquants (1 mL or less) of the sample
sample solutions in the 10–30 g Pu/L range. With special preparation and spectral
solution are diluted with 10 mL of a ferrous reductant/matrix
analysis techniques, the method has been applied to nitrate solutions in the 0.1–10
g Pu/L range.
solution to 1 g Pu/L, and measured.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.2 For chloride solutions, ascorbic acid is the recom-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mended reductant. Aliquants of the sample solution, each
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. containing 50–100 mg of plutonium, are diluted with 2 mL of
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1307 − 02 (2008)
zirconium solution to complex fluoride ions, 2 mL ascorbic lected. The spectral curve fitting software of the DAS is then
acid reductant solution, and 1.0 M HCl to a total volume of 25 used to quantitate the mathematically manipulated spectrum.
mL, yielding 2–4 g Pu/L solutions for measurement.
NOTE2—Caremustbetakeninthechoiceofthepreprocessingmethods
3.3 Plutonium concentration is determined from light ab-
(derivatives, mean centering, autoscaling and/or channel selection) as
sorption measurements taken on the sample solution in the thesemayaffecttherobustnessofthefinalmodel,particularlywithregard
to unknown interferences. Use of residual analysis will not always detect
blue-green region from 516 to 640 nm where a broad doublet
unknown intereferences and results will vary depending on the prepro-
band is observed. Spectral quantifying software capable of
cessing methods and models employed.
fitting the sample spectrum with spectral information from
standard solutions is used to calculate the plutonium concen- 5.2.2 This spectrophotometric assay method should not be
tration. Both commercially available (6) and custom-designed used on turbid (cloudy) solutions or solutions containing
(7-12) spectral fitting software have been developed which
undissolved material. In addition to visual or turbidity meter
may be used for plutonium measurements. The users of this
measurements,orboth,thepresenceofundissolvedsolidsmay
procedureareresponsibleforselectingorcustomizing,orboth,
be identified by the resulting shifts in the spectral baseline and
the spectral fitting (and instrument control) software that best
by elevated spectral fitting errors.
meets their individual measurement methodology and needs.
NOTE 3—Plutonium oxides, mixed oxides, and plutonium metals
Softwareselectionwilldictatemanyoftheproceduralspecifics
meeting the material specifications for which this test method is intended,
not included in this procedure. This procedure is intended to
will dissolve when procedures in Practice C1168 are followed. Failure to
address key measurement requirements and to allow users
achieve dissolution is an indication that the material does not meet the
discretion in establishing appropriate procedural details and
specifications, and the application of this test method for plutonium assay
technique variations. The software package selected should
must be verified by the user. The user and customer are cautioned: when
undissolvedsolidsthatpersistafterexhaustivedissolutioneffortsaretobe
include a feature that indicates the quality of spectral fit,
removed by filtration through filter paper or other inert material of
thereby providing information on the measurement reliability
appropriate porosity, the subsequent plutonium assay measurements
andthepresenceofinterferencesthatabsorblightorotherwise
require close scrutiny. While filtration of undissolved solids may permit
altertheplutonium(III)spectrumwithoutrequiringsupplemen-
the reliable measurement of the concentration of plutonium in the filtrate,
tal measurements.
the resulting analysis may not be representative of their source material.
Solidsmayindicateincompletedissolutionoftheplutoniuminthesample
material, not necessarily a plutonium-free refractory residue. When this
4. Significance and Use
technique is utilized in support of reprocessing operations, process
4.1 This test method is designed to determine whether a
solutionscontainingsolidsmaybeanindicationofincompletedissolution
given material meets the purchaser’s specification for pluto-
of the plutonium-bearing material being processed or of an error in
process operations. In addition to process control considerations, the
nium content.
undissolved solids may represent accountability and criticality control
problems.
5. Interferences
5.2.3 Strong oxidizing agents and complexing agents in
5.1 Materials meeting the applicable material specifications
sufficientconcentrationtopreventcompletereductiontypically
oftheASTMstandardforwhichthisprocedurewasdeveloped,
are not present in plutonium nitrate samples. Appreciable
when dissolved and diluted without introduction of interfering
concentrations of fluoride and sulfate anions have been found
contaminants as described in Practice C1168, will contain no
to interfere. The concentration of hydrofluoric acid, added to
interfering elements or species.
catalyzedissolutionofoxides,mayberemovedbyevaporation
NOTE 1—Fluoride, if present, would interfere if the zirconium, rou-
prior to measurement to ensure that the zirconium effectively
tinely added to the sample solution aliquant for the chloride matrix, were
complexesthetracesoffluorideion.Changesintheplutonium
omittedfromtheprocedure.Zirconiummaybeaddedtothenitratematrix.
spectrum from incomplete reduction due to oxidizing agents
Ferrous-Reductant Solution to handle fluorides if present. Zirconium,
whenused,shouldbeaddedtoallsamples,blanks,andstandardstoobtain
and shifts in the spectrum due to complexing agents are also
a consistent matrix. Refer to Specifications C833 and C757.
indicated by increases in the spectral curve fitting error.
5.2 Interferences are caused by: 1) materials that absorb
5.2.4 Anion identity and concentration will shift the loca-
light in the region of the plutonium absorption, 2) undissolved
tion and alter the shape of the absorption curve. The system
solids that cause light scattering, 3) strong oxidizing or
calibrationmustincludetheanionshifteffectbyencompassing
complexing agents that prevent complete reduction of the
the expected range of anion identities and concentrations or by
plutonium to the plutonium(III) oxidation state, and 4) anions
using appropriate spectral fitting features that identify and
that shift the spectrum.
correct for the effect.
5.2.1 Absorptionoflightintheregionofinterestbyanother
5.3 A study was conducted at the Los Alamos National
species is a potential interference. Identification of potentially
Laboratory to determine the immunity of the Pu(III) spectro-
interfering species and inclusion of their spectra in the spectral
photometric assay method to a diverse species of potential
curve fitting process will significantly reduce their effect.At a
interferences. The elements studied were element numbers 1,
minimum, sample measurements should be flagged when the
9, 11–13, 17, 19, 22–31, 35, 42, 44–46, 48, 50, 53, 57, 58, 60,
higher than normal fitting error occurs, , resulting from the
presence of unidentified absorbing species. Enhancement of 62, 73, 74, 76, 77, 79, 83, 90, 92, 93, and 95. Potential
interference from nitrate, phosphate, sulfate, and oxalic acid is
the spectral curve fitting capabilities of the DAS can be
achieved by taking double derivatives of the spectrum col- also documented (13).
C1307 − 02 (2008)
6. Apparatus (2 M)to90mLofsulfamicacid(1.5 M).Stir,thenadd175mL
of nitric acid (3.0 M) and dilute to 500 mL with water.
6.1 Diode Array Spectrophotometer (DAS)—wavelength
range 190–820 nm; wavelength accuracy6 2 nm; wavelength 7.5 Ferrous Sulfamate (Fe(NH SO ) , 2.0 M)—Prepare
2 3 2
fresh for the preparation of the ferrous-reductant solution.Add
reproducibility 60.05 nm; full dynamic range 0.0022 to 3.3;
photometric accuracy at 1AU with a NBS 931 filter at 512 nm 220 g of solid sulfamic acid to 450 mLof water, stir, and heat
at 70–80°C until dissolved. Continue stirring and heating,
is 60.005AU; baseline flatness <0.0013AU; noise at 500 nm
is0.0002AURMS;straylightmeasuredwithaHoya056filter while adding approximately 0.5-g portions of iron metal
4 0
powder (Fe ) until 56 g of iron have been dissolved in the
at 220 nm <0.05%;
heated sulfamic acid. Filter the solution while hot; allow to
6.2 Analytical Balance—readability of 0.1 mg; linearity 0.1
cool; then dilute to a final volume of 50 mL.
mg over any 10 g range and 0.2 mg over 160 g full scale.
NOTE 5—The dissolution of the sulfamic acid need not be quantitative
6.3 Solution Density Meter—readability of 0.1 mg/mL;
before beginning the addition of the iron powder. Excessive heating
precision of 0.3 mg/mL; linearity and accuracy 0.5 mg/mL
beyond the time required to achieve the dissolution of the sulfamic
over the range 0 to 2.0 g/mL.
acid/iron powder or at temperatures above 80°C will cause excessive
decomposition of the sulfamic acid
6.4 Adjustable, Fixed-Volume Pipetters—calibrated to de-
7.6 Hydrochloric Acid (HCl, 12 M)—Concentrated, sp gr
liver the desired range of volumes for sample and matrix-
1.19.
reductant solutions.
7.7 Hydrochloric Acid (HCl, 1.0 M)—Add 84 mLof hydro-
7. Reagents and Materials
chloric acid (sp gr 1.19) to approximately 500 mL of water.
7.1 Purity of Reagents—Reagent grade chemicals shall be Stir, then dilute to a final volume of 1 L.
used in all tests. Unless otherwise indicated, it is intended that
7.8 Nitric Acid (HNO , 15.8 M)—Concentrated, sp gr 1.42.
all reagents conform to the specifications of the Committee on
7.9 Nitric Acid (1.0 M)—Add 63 mL of nitric acid (sp gr
Analytical Reagents of theAmerican Chemical Society where
1.42) to approximately 500 mL of water. Stir, then dilute to a
such specifications are available. Other grades may be used,
final volume of 1 L.
provided it is first ascertained that the reagent is of sufficiently
7.10 Nitric Acid (3.0 M)—Add 190 mLof nitric acid (sp gr
high purity to permit its use without lessening the accuracy of
1.42) to approximately 500 mL of water. Stir, then dilute to a
the determination.
final volume of 1 L.
7.2 Purity of Water—Unless otherwise indicated, references
7.11 Plutonium Standard Solutions—Prepare standards
to water shall be understood to mean distilled or deionized
traceable to a national measurement system, which cover the
water.
range of concentrations over which sample measurements will
7.3 Ascorbic Acid-Reductant Solution (C H O , amin-
6 8 6
be performed.
oguanidine bicarbonate (CH N ·H CO ), 0.4 M in each
6 4 2 3
7.12 Sulfamic Acid (NH SO H, 1.5 M)—Dissol
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:C1307–95 Designation:C1307–02 (Reapproved 2008)
Standard Test Method for
Plutonium Assay by Plutonium (III) Diode Array
Spectrophotometry
This standard is issued under the fixed designation C 1307; 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 describes the determination of total plutonium as plutonium(III) in nitrate and chloride solutions. The
technique is applicable to solutions of plutonium dioxide powders and pellets (Test Methods C 697), nuclear grade mixed oxides
(Test Methods C 698), plutonium metal (Test Methods C 758), and plutonium nitrate solutions (Test Methods C 759). Solid
samplesaredissolvedusingtheappropriatedissolutiontechniquesdescribedinPracticeC 1168.Theuseofthistechniqueforother
plutonium-bearing materials has been reported (1-5), but final determination of applicability must be made by the user. The
applicable concentration range for plutonium sample solutions is 10–200 g Pu/L.
1.2
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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.
2. Referenced Documents
2.1 ASTM Standards:
C 697 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium Dioxide
Powders and Pellets
C 698 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U,
Pu)O )
C 757 Specification for Nuclear-Grade Plutonium Dioxide Powder, Sinterable
C 758 Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Nuclear-
Grade Plutonium Metal
C 759 Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Nuclear-
Grade Plutonium Nitrate Solutions
C 833 Specification for Sintered (Uranium-Plutonium) Dioxide Pellets
C 1168Practice for Preparation and Dissolution of Plutonium Materials for Analysis
2.2 American Chemical Society Standard:
Reagent Chemicals, American Chemical Society Specifications Practice for Preparation and Dissolution of Plutonium
Materials for Analysis
3. Summary of Method
3.1 In a diode array spectrophotometric measurement, as in a conventional spectrophotometric measurement, the substance
being determined absorbs light at frequencies characteristic of that substance. The amount of light absorbed at each wavelength
is directly proportional to the concentration of the species of interest. The absorption is a function of the oxidation state and the
complexation obtained in the solution matrix selected for measurement. Beer’s Law permits quantifying the species of interest
relative to a traceable standard when both solutions are measured under the same conditions. The array of photosensitive diodes
permits the (virtually) simultaneous collection of spectral information over the entire range of the instrument, for example,
This test method is under the jurisdiction ofASTM Committee C-26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.
Current edition approved Sept. 10, 1995. Published November 1995.
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.
Current edition approved June 1, 2008. Published July 2008. Originally approved in 1995. Last previous edition approved in 2002 as C 1307 – 02.
Forsolidsamples,selectthesamplesizeanddissolvedsolutionweighttoyieldsamplesolutionsinthe10–30gPu/Lrange.Withspecialpreparationandspectralanalysis
techniques, the method has been applied to nitrate solutions in the 0.1–10 g Pu/L range.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 12.01.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.
C1307–02 (2008)
190–820 nm (or any selected portion of the range). An entire absorption spectrum can be obtained in 0.1 s; however, optimum
precision is obtained from multiple spectra collected over a 4-s period.
3.2 Reduction to plutonium(III) is accomplished by the addition of a measured quantity of reductant solution to the sample
aliquant.
3.2.1 For nitrate solutions, ferrous sulfamate is the recommended reductant.Aliquants (1 mLor less) of the sample solution are
diluted with 10 mL of a ferrous reductant/matrix solution to 1 g Pu/L, and measured.
3.2.2 For chloride solutions, ascorbic acid is the recommended reductant. Aliquants of the sample solution, each containing
50–100 mg of plutonium, are diluted with 2 mL of zirconium solution to complex fluoride ions, 2 mL ascorbic acid reductant
solution, and 1.0 M HCl to a total volume of 25 mL, yielding 2–4 g Pu/L solutions for measurement.
3.3 Plutonium concentration is determined from light absorption measurements taken on the sample solution in the blue-green
region from 516 to 640 nm where a broad doublet band is observed. Spectral quantifying software capable of fitting the sample
spectrum with spectral information from standard solutions is used to calculate the plutonium concentration. Both commercially
available (6) and custom-designed (7-12) spectral fitting software have been developed which may be used for plutonium
measurements.Theusersofthisprocedureareresponsibleforselectingorcustomizing,orboth,thespectralfitting(andinstrument
control) software that best meets their individual measurement methodology and needs. Software selection will dictate many of
the procedural specifics not included in this procedure. This procedure is intended to address key measurement requirements and
to allow users discretion in establishing appropriate procedural details and technique variations. The software package selected
should include a feature that indicates the quality of spectral fit, thereby providing information on the measurement reliability and
the presence of interferences that absorb light or otherwise alter the plutonium(III) spectrum without requiring supplemental
measurements.
4. Significance and Use
4.1 This test method is designed to determine whether a given material meets the purchaser’s specification for plutonium
content.
5. Interferences
5.1 Materials meeting the applicable material specifications of the ASTM standard for which this procedure was developed,
when dissolved and diluted without introduction of interfering contaminants as described in Practice C 1168, will contain no
interfering elements or species.
NOTE 1—Fluoride, if present, would interfere if the zirconium, routinely added to the sample solution aliquant for the chloride matrix, were omitted
from the procedure. Zirconium may be added to the nitrate matrix. Ferrous-Reductant Solution to handle fluorides if present. Zirconium, when used,
should be added to all samples, blanks, and standards to obtain a consistent matrix. Refer to Specifications C 833 and C 757.
5.2 Interferences are caused by: 1) materials that absorb light in the region of the plutonium absorption, 2) undissolved solids
that cause light scattering, 3) strong oxidizing or complexing agents that prevent complete reduction of the plutonium to the
plutonium(III) oxidation state, and 4) anions that shift the spectrum.
5.2.1Absorption of light in the region of interest by another species is a potential interference. Identification of potentially
interfering species and inclusion of their spectra in the spectral curve fitting process will significantly reduce their effect. At a
minimum, sample measurements should be flagged when the higher than normal fitting error, resulting from the presence of
unidentifiedabsorbingspecies,occurs.EnhancementofthespectralcurvefittingcapabilitiesoftheDAScanbeachievedbytaking
double derivatives of the spectrum collected. The spectral curve fitting software of the DAS is then used to quantitate the
mathematically manipulated spectrum.
5.2.1 Absorption of light in the region of interest by another species is a potential interference. Identification of potentially
interfering species and inclusion of their spectra in the spectral curve fitting process will significantly reduce their effect. At a
minimum, sample measurements should be flagged when the higher than normal fitting error occurs, , resulting from the presence
of unidentified absorbing species. Enhancement of the spectral curve fitting capabilities of the DAS can be achieved by taking
double derivatives of the spectrum collected. The spectral curve fitting software of the DAS is then used to quantitate the
mathematically manipulated spectrum.
NOTE 2—Care must be taken in the choice of the preprocessing methods (derivatives, mean centering, autoscaling and/or channel selection) as these
may affect the robustness of the final model, particularly with regard to unknown interferences. Use of residual analysis will not always detect unknown
intereferences and results will vary depending on the preprocessing methods and models employed.
5.2.2 Thisspectrophotometricassaymethodshouldnotbeusedonturbid(cloudy)solutionsorsolutionscontainingundissolved
material. In addition to visual or turbidity meter measurements, or both, the presence of undissolved solids may be identified by
the resulting shifts in the spectral baseline and by elevated spectral fitting errors.
NOTE1—Plutonium oxides, mixed oxides, and plutonium metals meeting the material specifications for which this test method is intended, will dissolve
when procedures in Practice C1168 are followed. Failure to achieve dissolution is an indication that the material does not meet the specifications, and
the application of this test method for plutonium assay must be verified by the user. 3—Plutonium oxides, mixed oxides, and plutonium metals meeting
the material specifications for which this test method is intended, will dissolve when procedures in Practice C 1168 are followed. Failure to achieve
dissolution is an indication that the material does not meet the specifications, and the application of this test method for plutonium assay must be verified
C1307–02 (2008)
by the user. The user and customer are cautioned: when undissolved solids that persist after exhaustive dissolution efforts are to be removed by filtration
through filter paper or other inert material of appropriate porosity, the subsequent plutonium assay measurements require close scrutiny. While filtration
of undissolved solids may permit the reliable measurement of the concentration of plutonium in the filtrate, the resulting analysis may not be
representative of their source material. Solids may indicate incomplete dissolution of the plutonium in the sample material, not necessarily a
plutonium-free refractory residue. When this technique is utilized in support of reprocessing operations, process solutions containing solids maybean
indication of incomplete dissolution of the plutonium-bearing material being processed or of an error in process operations. In addition to process control
considerations, the undissolved solids may represent accountability and criticality control problems.
5.2.3 Strong oxidizing agents and complexing agents in sufficient concentration to prevent complete reduction typically are not
present in plutonium nitrate samples.Appreciable concentrations of fluoride and sulfate anions have been found to interfere. The
concentration of hydrofluoric acid, added to catalyze dissolution of oxides, may be removed by evaporation prior to measurement
to ensure that the zirconium effectively complexes the traces of fluoride ion. Changes in the plutonium spectrum from incomplete
reductionduetooxidizingagentsandshiftsinthespectrumduetocomplexingagentsarealsoindicatedbyincreasesinthespectral
curve fitting error.
5.2.4Excessive anion 5.2.4 Anion identity and concentration will shift the location and alter the shape of the absorption curve.
The system calibration must include the anion shift effect by using matrix-matched standards for calibrationencompassing the
expected range of anion identities and concentrations or by using appropriate spectral fitting features that identify and correct for
the effect.
5.3 Astudy was conducted at the LosAlamos National Laboratory to determine the immunity of the Pu(III) spectrophotometric
assay method to a diverse species of potential interferences. The elements studied were element numbers 1, 9, 11–13, 17, 19,
22–31, 35, 42, 44–46, 48, 50, 53, 57, 58, 60, 62, 73, 74, 76, 77, 79, 83, 90, 92, 93, and 95. Potential interference from nitrate,
phosphate, sulfate, and oxalic acid is also documented (13).
6. Apparatus
6.1 Diode Array Spectrophotometer (DAS)—wavelength range 190–820 nm; wavelength accuracy6 2 nm; wavelength
reproducibility 60.05 nm; full dynamic range 0.0022 to 3.3; photometric accuracy at 1AU, 512 nm,AU with a NBS 931 filter at
512 nm is 60.005AU; baseline flatness <0.0013AU; noise at 500 nm is 0.0002AU RMS; stray light measured with a Hoya 056
filter at 220 nm <0.05 %; stray light measured with a 056 filter <0.05%.
6.2 Analytical Balance—readability of 0.1 mg; linearity 0.1 mg over any 10 g range and 0.2 mg over 160 g full scale.
6.3 Solution Density Meter—readability of 0.1 mg/mL; precision of 0.3 mg/mL; linearity and accuracy 0.5 mg/mL over the
range 0 to 2.0 g/mL.
6.4 Adjustable, Fixed-Volume Pipetters—calibrated to deliver the desired range of volumes for sample and matrix-reductant
solutions.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents 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 it is first ascertained that the reagent is of suffic
...
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