ASTM C759-18

Standard Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Nuclear-Grade Plutonium Nitrate Solutions

SIGNIFICANCE AND USE
4.1 These test methods are designed to show whether a given material meets the purchaser's specifications.  
4.1.1 An assay is performed to determine whether the material has the specified plutonium content.  
4.1.2 Determination of the isotopic content of the plutonium in the plutonium-nitrate solution is made to establish whether the effective fissile content is in compliance with the purchaser's specifications.  
4.1.3 Impurity content is determined by a variety of methods to ensure that the maximum concentration limit of specified impurities is not exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC).  
4.2 Fitness for Purpose of Safeguards and Nuclear Safety Applications—Methods intended for use in safeguards and nuclear safety applications shall meet the requirements specified by Guide C1068 for use in such applications.
SCOPE
1.1 These test methods cover procedures for the chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions to determine compliance with specifications.  
1.2 The analytical procedures appear in the following order:    
Sections  
Plutonium by Controlled-Potential Coulometry  
2  
Plutonium by Amperometric Titration with Iron(II)  
2  
Plutonium by Diode Array Spectrophotometry  
Free Acid by Titration in an Oxalate Solution  
8 to 15  
Free Acid by Iodate Precipitation-Potentiometric Titration
Test Method  
16 to 22  
Uranium by Arsenazo I Spectrophotometric Test Method  
23 to 33  
Thorium by Thorin Spectrophotometric Test Method  
34 to 42  
Iron by 1,10-Phenanthroline Spectrophotometric Test Method  
43 to 50  
Impurities by ICP-AES  
Chloride by Thiocyanate Spectrophotometric Test Method  
51 to 58  
Fluoride by Distillation-Spectrophotometric Test Method  
59 to 66  
Sulfate by Barium Sulfate Turbidimetric Test Method  
67 to 74  
Isotopic Composition by Mass Spectrometry  
75 to 76  
Plutonium-238 Isotopic Abundance by Alpha Spectrometry  
Americium-241 by Extraction and Gamma Counting  
77 to 85  
Americium-241 by Gamma Counting  
86 to 94  
Gamma-Emitting Fission Products, Uranium, and Thorium by Gamma-Ray Spectroscopy  
94 to 102  
Rare Earths by Copper Spark Spectrochemical Test Method  
103 to 105  
Tungsten, Niobium (Columbium), and Tantalum by Spectro-
chemical Test Method  
106 to 114  
Sample Preparation for Spectrographic Analysis for General
Impurities  
115 to 118  
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific safeguard and safety hazard statements, see Section 6.  
1.5 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-Aug-2018
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: C26 - Nuclear Fuel Cycle
• Drafting Committee: C26.05 - Methods of Test

Relations

• Replaces: ASTM C759-10 - Standard Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of Nuclear-Grade Plutonium Nitrate Solutions
• Effective Date: 01-Sep-2018
• Refers: ASTM C859-24 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C1432-23 - Standard Test Method for Determination of Impurities in Plutonium: Acid Dissolution, Ion Exchange Matrix Separation, and Inductively Coupled Plasma-Atomic Emission Spectroscopic (ICP/AES) Analysis
• Effective Date: 01-Dec-2023
• Refers: ASTM C1268-23 - Standard Test Method for Quantitative Determination of ²⁴¹Am in Plutonium by Gamma-Ray Spectrometry
• Effective Date: 01-Oct-2023
• Refers: ASTM C1156-18 - Standard Guide for Establishing Calibration for a Measurement Method Used to Analyze Nuclear Fuel Cycle Materials
• Effective Date: 01-Sep-2018
• Refers: ASTM C1297-18 - Standard Guide for Qualification of Laboratory Analysts for the Analysis of Nuclear Fuel Cycle Materials
• Effective Date: 01-Jul-2018
• Refers: ASTM C1415-18 - Standard Test Method for ²³⁸Pu Isotopic Abundance By Alpha Spectrometry
• Effective Date: 01-Jun-2018
• Refers: ASTM E50-17 - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 01-Sep-2017
• Refers: ASTM C852/C852M-16 - Standard Guide for Design Criteria for Plutonium Gloveboxes
• Effective Date: 01-Nov-2016
• Refers: ASTM E50-11(2016) - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 01-Aug-2016
• Refers: ASTM C697-16 - Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium Dioxide Powders and Pellets
• Effective Date: 01-Jun-2016
• Refers: ASTM C1268-15 - Standard Test Method for Quantitative Determination of ²⁴¹Am in Plutonium by Gamma-Ray Spectrometry
• Effective Date: 01-Jun-2015
• Refers: ASTM C1432-15 - Standard Test Method for Determination of Impurities in Plutonium: Acid Dissolution, Ion Exchange Matrix Separation, and Inductively Coupled Plasma-Atomic Emission Spectroscopic (ICP/AES) Analysis
• Effective Date: 01-Jun-2015
• Refers: ASTM C1128-15 - Standard Guide for Preparation of Working Reference Materials for Use in Analysis of Nuclear Fuel Cycle Materials
• Effective Date: 01-Feb-2015
• Refers: ASTM C859-14a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Jun-2014

Overview

ASTM C759-18 is a comprehensive international standard that specifies test methods for the chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions. Issued by ASTM International under the committee C26 on Nuclear Fuel Cycle, this standard serves as a fundamental resource for laboratories, manufacturers, and regulatory bodies involved in nuclear material analysis and quality control.

The standard defines a wide array of analytical procedures designed to verify if nuclear-grade plutonium nitrate solutions meet strict purchaser specifications concerning plutonium content, isotopic composition, free acid levels, and impurity concentrations. These standardized analytical methods enable consistent, reliable compliance assessment while ensuring robust safeguards and nuclear safety.

Key Topics

• Plutonium Assay Methods: Controlled-potential coulometry, amperometric titration, and spectrophotometry for accurate plutonium quantification.
• Isotopic Analysis: Determination of plutonium isotopic composition to confirm effective fissile content using mass spectrometry and alpha spectrometry.
• Impurity Assessment: Spectrochemical, nuclear, and mass spectrometric techniques to detect and quantify impurities such as uranium, thorium, iron, rare earths, chloride, fluoride, and sulfate.
• Free Acid Determination: Titration techniques, including oxalate solution and iodate precipitation-potentiometric titration, to measure free acid content.
• Radiochemical Analysis: Methods for assessing Americium-241 and gamma-emitting fission products.
• Sample Handling and Safety: Guidelines for safe sampling, handling of radioactive materials, use of appropriate laboratory facilities, and adherence to rigorous health and environmental standards.

Applications

ASTM C759-18 is essential for various applications within the nuclear industry, such as:

• Nuclear Material Quality Control: Ensuring that plutonium nitrate solutions meet precise content and purity specifications required for nuclear fuel fabrication and processing.
• Regulatory Compliance and Safeguards: Supporting safeguards, accounting, and nuclear safety by providing traceable, standardized analysis protocols necessary for compliance with national and international regulations.
• Laboratory Accreditation and Quality Assurance: Establishing repeatable, validated test methods supports laboratory accreditation and ongoing quality assurance programs in nuclear analytical laboratories.
• Material Traceability: When combined with certified reference materials, these methods help demonstrate measurement traceability to national standards, critical for both commercial and governmental nuclear operations.
• Research and Development: Facilitating fundamental and applied research concerning nuclear-grade plutonium nitrate, measurement science, and impurity control in advanced nuclear fuel cycles.

Related Standards

For a more complete analytical framework and interoperability in the nuclear materials sector, ASTM C759-18 references or is used alongside several other ASTM standards, including:

• ASTM C697: Chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade plutonium dioxide.
• ASTM C859: Terminology relating to nuclear materials.
• ASTM C1068: Guide for qualification of measurement methods in nuclear laboratories.
• ASTM C1108, C1165, and C1307: Specific test methods for plutonium quantification.
• ASTM C1432: Determination of impurities in plutonium by acid dissolution and ICP-AES.
• ASTM D1193: Specification for reagent water in analytical applications.

These related standards provide further detail on test methodologies, terminology, quality assurance, and laboratory practices, ensuring the integrity and accuracy of nuclear chemical analysis processes.

---

By adhering to ASTM C759-18, industry stakeholders can achieve reliable, repeatable assessments of nuclear-grade plutonium nitrate solutions, supporting the nuclear sector’s quality, safety, and compliance goals.

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: C759 − 18
Standard Test Methods for
Chemical, Mass Spectrometric, Spectrochemical, Nuclear,
and Radiochemical Analysis of Nuclear-Grade Plutonium
Nitrate Solutions
This standard is issued under the fixed designation C759; 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 mine the applicability of regulatory limitations prior to use.
For specific safeguard and safety hazard statements, see
1.1 These test methods cover procedures for the chemical,
Section 6.
mass spectrometric, spectrochemical, nuclear, and radiochemi-
1.5 This international standard was developed in accor-
cal analysis of nuclear-grade plutonium nitrate solutions to
dance with internationally recognized principles on standard-
determine compliance with specifications.
ization established in the Decision on Principles for the
1.2 Theanalyticalproceduresappearinthefollowingorder:
Development of International Standards, Guides and Recom-
Sections
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
Plutonium by Controlled-Potential Coulometry
Plutonium by Amperometric Titration with Iron(II)
2. Referenced Documents
Plutonium by Diode Array Spectrophotometry
Free Acid by Titration in an Oxalate Solution 8 to 15
2.1 ASTM Standards:
Free Acid by Iodate Precipitation-Potentiometric Titration 16 to 22
Test Method C697Test Methods for Chemical, Mass Spectrometric, and
Uranium by Arsenazo I Spectrophotometric Test Method 23 to 33
Spectrochemical Analysis of Nuclear-Grade Plutonium
Thorium by Thorin Spectrophotometric Test Method 34 to 42
Dioxide Powders and Pellets
Iron by 1,10-Phenanthroline Spectrophotometric Test Method 43 to 50
Impurities by ICP-AES C852/C852M Guide for Design Criteria for Plutonium
Chloride by Thiocyanate Spectrophotometric Test Method 51 to 58
Gloveboxes
Fluoride by Distillation-Spectrophotometric Test Method 59 to 66
C859Terminology Relating to Nuclear Materials
Sulfate by Barium Sulfate Turbidimetric Test Method 67 to 74
Isotopic Composition by Mass Spectrometry 75 to 76
C1009Guide for Establishing and Maintaining a Quality
Plutonium-238 Isotopic Abundance by Alpha Spectrometry
AssuranceProgramforAnalyticalLaboratoriesWithinthe
Americium-241 by Extraction and Gamma Counting 77 to 85
Nuclear Industry
Americium-241 by Gamma Counting 86 to 94
Gamma-Emitting Fission Products, Uranium, and Thorium by 94 to 102
C1068Guide for Qualification of Measurement Methods by
Gamma-Ray Spectroscopy
a Laboratory Within the Nuclear Industry
Rare Earths by Copper Spark Spectrochemical Test Method 103 to 105
C1108Test Method for Plutonium by Controlled-Potential
Tungsten, Niobium (Columbium), and Tantalum by Spectro- 106 to 114
chemical Test Method
Coulometry
Sample Preparation for Spectrographic Analysis for General 115 to 118
C1128Guide for Preparation of Working Reference Materi-
Impurities
als for Use in Analysis of Nuclear Fuel Cycle Materials
1.3 The values stated in SI units are to be regarded as
C1156Guide for Establishing Calibration for a Measure-
standard. The values given in parentheses are for information
ment Method Used toAnalyze Nuclear Fuel Cycle Mate-
only.
rials
1.4 This standard does not purport to address all of the
C1165 Test Method for Determining Plutonium by
safety concerns, if any, associated with its use. It is the
Controlled-Potential Coulometry in H SO at a Platinum
2 4
responsibility of the user of this standard to establish appro-
Working Electrode
priate safety, health, and environmental practices and deter-
C1206Test Method for Plutonium by Iron (II)/Chromium
(VI) Amperometric Titration (Withdrawn 2015)
These test methods are under the jurisdiction of ASTM Committee C26 on
Nuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.05 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Methods of Test. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved Sept. 1, 2018. Published October 2018. Originally Standardsvolume information, refer to the standard’s Document Summary page on
approved in 1973. Last previous edition approved in 2010 as C759–10. DOI: the ASTM website
10.1520/C0759-18. The last approved version of this historical standard is referenced on
Discontinued as of November 15, 1992. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C759 − 18
C1210Guide for Establishing a Measurement System Qual- cal Society, where such specifications are available. Other
ity Control Program for Analytical Chemistry Laborato- grades may be used, provided it is first ascertained that the
reagent is of sufficiently high purity to permit its use without
ries Within the Nuclear Industry
lessening the accuracy of the determination.
C1235 Test Method for Plutonium by Titanium(III)/
Cerium(IV) Titration (Withdrawn 2005)
5.2 Purity of Water—Unless otherwise indicated, reference
C1268 Test Method for Quantitative Determination of
towatershallbeunderstoodtomeanreagentwaterconforming
Am in Plutonium by Gamma-Ray Spectrometry
to Specification D1193.
C1297Guide for Qualification of Laboratory Analysts for
6. Safety Hazards
the Analysis of Nuclear Fuel Cycle Materials
C1307Test Method for PlutoniumAssay by Plutonium (III)
6.1 Since plutonium bearing materials are radioactive and
Diode Array Spectrophotometry
toxic,adequatelaboratoryfacilities,glovedboxes,fumehoods,
C1415Test Method for Pu Isotopic Abundance By Alpha
etc., along with safe techniques, must be used in handling
Spectrometry
samplescontainingthesematerials.Adetaileddiscussionofall
C1432Test Method for Determination of Impurities in the precautions necessary is beyond the scope of these test
methods; however, personnel who handle these materials
Plutonium: Acid Dissolution, Ion Exchange Matrix
should be familiar with such safe handling practices as are
Separation, and Inductively Coupled Plasma-Atomic
given in Guide C852/C852M and in Refs (1) through (2).
Emission Spectroscopic (ICP/AES) Analysis
D1193Specification for Reagent Water
6.2 Adequate laboratory facilities, such as fume hoods and
E50Practices for Apparatus, Reagents, and Safety Consid-
controlledventilation,alongwithsafetechniques,mustbeused
erations for Chemical Analysis of Metals, Ores, and
in this procedure. Extreme care should be exercised in using
Related Materials hydrofluoric and other hot, concentrated acids. Use of proper
E115Practice for Photographic Processing in Optical Emis- gloves is recommended. Refer to the laboratory’s chemical
hygiene plan and other applicable guidance for handling
sion Spectrographic Analysis (Withdrawn 2002)
chemical and radioactive materials and for the management of
E116Practice for Photographic Photometry in Spectro-
radioactive, mixed, and hazardous waste.
chemical Analysis (Withdrawn 2002)
6.3 Hydrofluoric acid is a highly corrosive acid that can
3. Terminology
severely burn skin, eyes, and mucous membranes. Hydroflu-
oric acid is similar to other acids in that the initial extent of a
3.1 For definitions of terms used in this test method but not
burn depends on the concentration, the temperature, and the
defined herein, refer to Terminology C859.
duration of contact with the acid. Hydrofluoric acid differs
from other acids because the fluoride ion readily penetrates the
4. Significance and Use
skin, causing destruction of deep tissue layers. Unlike other
acids that are rapidly neutralized, hydrofluoric acid reactions
4.1 These test methods are designed to show whether a
with tissue may continue for days if left untreated. Due to the
given material meets the purchaser’s specifications.
serious consequence of hydrofluoric acid burns, prevention of
4.1.1 An assay is performed to determine whether the
exposure or injury of personnel is the primary goal. Utilization
material has the specified plutonium content.
of appropriate laboratory controls (hoods) and wearing ad-
4.1.2 Determinationoftheisotopiccontentoftheplutonium
equate personal protective equipment to protect from skin and
in the plutonium-nitrate solution is made to establish whether
eye contact is essential.
the effective fissile content is in compliance with the purchas-
er’s specifications.
7. Sampling
4.1.3 Impurity content is determined by a variety of meth-
7.1 A sample representative of the lot shall be taken from
ods to ensure that the maximum concentration limit of speci-
each lot into a container or multiple containers that are of such
fied impurities is not exceeded. Determination of impurities is
composition that corrosion, chemical change, radiolytic de-
also required for calculation of the equivalent boron content
composition products, and method of loading or sealing will
(EBC).
not disturb the chemical or physical properties of the sample.
(Aflame-sealed quartz vial that is suitable for accommodating
4.2 Fitness for Purpose of Safeguards and Nuclear Safety
pressure resulting from radiolytic decomposition is generally
Applications—Methods intended for use in safeguards and
considered to be an acceptable sample container.)
nuclear safety applications shall meet the requirements speci-
fied by Guide C1068 for use in such applications.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
5. Reagents and Materials
listed by the American Chemical Society, see Analar Standards for Laboratory
5.1 Purity of Reagents—Reagent grade chemicals shall be Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
used in all test methods. Unless otherwise indicated, it is
MD.
intended that all reagents shall conform to the specifications of 6
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
theCommitteeonAnalyticalReagentsoftheAmericanChemi- these test methods.
C759 − 18
7.2 Sample size shall be sufficient to perform the following: 11. Apparatus
7.2.1 Assay and acceptance tests at the seller’s plant,
11.1 Magnetic Stirrer.
7.2.2 Assay and acceptance tests at the purchaser’s plant,
11.2 Microburet.
and
11.3 Micropipets.
7.2.3 Referee tests in the event they become necessary.
11.4 pH Meter.
7.3 All samples shall be identified clearly, including the
seller’s lot number.
12. Reagents and Materials
7.3.1 Alot is defined as any quantity of aqueous plutonium
12.1 Ammonium Oxalate Solution, saturated.
nitrate solution that is uniform in isotopic, chemical, and
12.2 Nitric Acid (3.50 N)—Prepare solution by diluting
physicalcharacteristicsbyvirtueofhavingbeenmixedinsuch
concentrated nitric acid (HNO , sp gr 1.42) with water.
a manner as to be thoroughly homogeneous.
Standardizebytitrating0.500-mLaliquotswith0.100 NNaOH
7.3.2 All containers used for a lot shall be identified
solution.
positively as containing material from a particular homoge-
neous solution.
12.3 Sodium Hydroxide Solution (0.100 N)—Prepare and
standardize in accordance with Practices E50.
PLUTONIUM BY CONTROLLED-POTENTIAL
COULOMETRY
13. Procedure
(This test method was discontinued in 1992 and replaced by
13.1 Transfer 1.0 mL of saturated ammonium oxalate solu-
Test Method C1165.)
tion to a small vial and dilute to about 2 mL with water.
13.2 Add a stirring bar and insert the electrodes and start
PLUTONIUM BY CONTROLLED-POTENTIAL
stirrer. When the pH value becomes stable, record the value as
COULOMETRY
the pH of reagent.
(With appropriate sample preparation, controlled-potential
coulometric measurement as described in Test Method
NOTE 2—Normally, the pH value for the saturated solution is approxi-
C1108 may be used for plutonium determination.) mately 6.4.
13.3 Add 20 µL of sample to the vial, rinse the pipet
PLUTONIUM BY AMPEROMETRIC TITRATION
thoroughly with water, and stir the solution for 1 min.
WITH IRON(II)
13.4 Titrate with 0.100 N NaOH solution to within one pH
(This test method was discontinued in 1992 and replaced by
unit of the end point; then, by adding successively smaller
Test Method C1206.)
increments, titrate to the pH of the ammonium oxalate reagent
TEST METHOD FOR PLUTONIUM ASSAY BY
and record the volume of titrant.
PLUTONIUM(III) DIODE ARRAY
NOTE 3—Allow time for the pH reading to stabilize between additions
SPECTROPHOTOMETRY
of titrant as the end point is approached.
(With appropriate sample preparation, the measurement de-
13.5 Make a daily check of the system by adding 20 µL of
scribed in Test Method C1307 may be used for plutonium
3.50 N HNO to a sample that has already been titrated to the
determination.)
end point and titrate with standard 0.100 N NaOH solution
back to the same pH.
FREE ACID BY TITRATION IN AN OXALATE
SOLUTION
14. Calculation
+
14.1 Calculate the free acid (H , N) as follows:
8. Scope
H , N 5 ~A 3 N!/V (1)
8.1 Thistestmethodcoversthedeterminationoffreeacidin
plutonium nitrate solutions (3, 4).
where:
A = microlitresofstandardNaOHsolutionrequiredtotitrate
9. Summary of Test Method
sample,
9.1 Freeacidisdeterminedbytitratinganaliquotofsample, N = normality of NaOH standard solution, and
V = volume of sample, µL.
which contains an excess of ammonium oxalate added to
complex the plutonium, back to the original pH of the
15. Precision and Bias
ammonium oxalate solution with standard sodium hydroxide
15.1 Precision—Of individual results, 65% at the 95%
solution. Micropipets and microburets are required to measure
confidence level.
the small volume of sample and titrant used.
15.2 Bias—99.4%.
10. Interferences
FREE ACID BY IODATE PRECIPITATION-
10.1 Any metal ions not complexed by oxalate which form
POTENTIOMETRIC TITRATION TEST METHOD
precipitatesatthepHoftheendpointofthetitrationwillcause
interference in this test method. 16. Scope
16.1 This test method covers the determination of free acid
NOTE 1—A “rule of thumb” is that 1 mL of saturated ammonium
oxalate solution will complex 6.4 mg of plutonium. in strong acid solutions of plutonium nitrate.
C759 − 18
17. Summary of Test Method
N = normality of NaOH solution,
V = millilitres of NaOH solution to titrate sample aliquot,
s
17.1 Freeacidisdeterminedbypotentiometrictitrationwith
V = millilitresofNaOHsolutiontotitratereagentblank,and
b
standard sodium hydroxide solution after precipitation and
S = millilitres of sample aliquot.
subsequent removal of plutonium (up to 50 mg) as plutonium
iodate.
22. Precision and Bias
22.1 The relative standard deviation, based on 49 titrations,
18. Interferences
is 0.9% for aliquots of sample containing a minimum of 0.2
18.1 Any hydrolyzable ions that are not precipitated with
milliequivalents of acid.
iodate will interfere.
22.2 Between 99 and 100% of the free acid in standard
plutonium(IV)solutionshasbeenmeasuredbythisprocedure;
19. Reagents and Materials
however, when the plutonium was in the (III) oxidation state,
19.1 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
the results showed a negative bias of as much as 8% (5).
chloric acid (HCl).
URANIUM BY ARSENAZO I
19.2 Nitric Acid (1 + 14)—Dilute 14 volumes of water with
SPECTROPHOTOMETRIC TEST METHOD
1 volume of concentrated nitric acid (HNO , sp gr 1.42).
19.3 Potassium Iodate (0.3 M)—Dissolve 64.2 g of potas-
23. Scope
siumiodate(KIO )in900mLofwater,adjustthepHto4.3by
23.1 This test method covers the determination of uranium
adding HNO (1+14), and dilute to 1 L with water.
in the range from 300 to 3000 µg/g of plutonium in plutonium
19.4 Sodium Hydroxide (0.3 M)—Prepareandstandardizein
nitrate solutions.
accordance with Practices E50 after making the following
alterations:Use15mLoftheNaOHsolution(50g/50mL),and
24. Summary of Test Method
instep42.2,transfer1.200gofNationalInstituteforStandards
24.1 Plutonium is reduced to Pu(III) in HCl (1+1) solution
andTechnology (NIST) potassium acid phthalate SRM 84 h or
with hydroxylamine hydrochloride. The uranium and pluto-
itsreplacementtoa250-mLErlenmeyerflaskinsteadof0.4000
niumarethenseparatedbyanionexchange,andtheuraniumis
g.
determined by measuring the absorbance of the U(VI)-
Arsenazo I complex in a 1-cm cell at a wavelength of 600 nm
20. Procedure
versus a reagent blank.
20.1 Pipet 50 mL of KIO (0.3 M) into a beaker and stir
while adding an aliquot of sample solution containing no
25. Interference
greater than 50 mg of plutonium.
25.1 Iron at 500 µg/g of plutonium is the most likely
20.2 After precipitation is complete, filter the solution
interference in this test method.
through either a medium porosity glass frit or a fine textured
26. Apparatus
acid-washed filter paper and collect the filtrate in a beaker.
20.3 Washtheprecipitatewithtwo25-mLportionsof0.3 M 26.1 Columns, ion exchange, 1 by 10 cm. Columns can be
made by sealing a 1-cm diameter filtering tube with a coarse
KIO solution,andcombinethewashingswiththefiltratefrom
step 20.2. glass frit to the bottom of a 40-mLcentrifuge tube and cutting
the tube off diagonally just below the frit.
20.4 Dissolve the precipitate in HNO (sp gr 1.42) or HCl
(sp gr 1.19) and transfer to a residue bottle. 26.2 Spectrophotometer and 1-cm Matched Cells.
20.5 Transfer the sample from 20.3 to the titration
27. Reagents and Materials
apparatus,positiontheelectrodesandamagneticstirringbarin
27.1 Ammonium Hydroxide (1 + 13)—Dilute 1 volume of
the solution, and start the stirrer.
concentrated ammonium hydroxide (NH OH, sp gr 0.90) with
20.6 Titratethefreeacidinthesolutionbyaddingthe0.3 M
13 volumes of water.
NaOH solution from a 5-mL buret and plot the titration curve
27.2 Arsenazo I Reagent (0.500 g/L)—Dissolve 250 mg of
(pH versus mL NaOH solution).
the purified reagent [(3-2-arsonophenylazo)-4,5-dihydroxy-2,7
20.7 Determine the end point of the titration from the
naphthalenedisulfonic acid, disodium salt] in water and dilute
midpoint of the inflection on the titration curve and record the
to 500 mL with water.
volume of 0.3 M NaOH solutions by the steps given in 20.5
NOTE 4—Purify reagents as follows:To a saturated aqueous solution of
through 20.7 of the procedure.
Arsenazo I, add an equal volume of HCl (sp gr 1.19), filter the orange
precipitate, wash with acetonitrile, and dry at 100°C for 1 h.
21. Calculation
27.3 Hydrochloric Acid (0.1 N)—To prepare, dilute 8.3 mL
+
21.1 Calculate the free acid (H , N) as follows:
of hydrochloric acid (HCl, sp gr 1.19) to 1 L with water.
H , N 5 V 2 V N/S (2)
~ !
s b
27.4 Hydrochloric Acid (1 + 1)—To prepare, dilute 500 mL
where: of hydrochloric acid (HCl, sp gr 1.19) to 1 L with water.
C759 − 18
27.5 Hydroxylamine Hydrochloride Solution (100 g/L)— 29.2 Add 0.0, 1.0, 4.0, 7.0, and 10.0 mL of uranium
Dissolve 10 g of (NH OH·HCl) in water and dilute to 100 mL standardsolution(20mg/L),respectively,toeachofthe5pairs
with water. of solutions prepared in 29.1 and evaporate to dryness.
27.6 Nitric Acid (1 + 2)—Dilute 100 mL of nitric acid
29.3 Add4.0mLofHCl(1+1)toeachbeakeranddissolve
(HNO , sp gr 1.42) to 300 mL with water.
the residue.
27.7 Phenolphthalein Solution (0.25 g/L)—Dissolve 25 mg
29.4 Add 3 mL of hydroxylamine hydrochloride solution
of phenolphthalein in a water-ethanol (1+1) solution and
(NH OH·HCl, 100 g/L) to each beaker and warm the solution
dilute to 100 mL with the water-ethanol solution.
under infrared lamps until the plutonium is reduced to Pu(III)
as indicated by the blue color. If the solution is not blue, add
27.8 Plutonium Matrix Calibration Solution (7 g/L)—
more NH OH·HCl solution and warm again.
Dissolve approximately 700 mg of plutonium metal, NIST 2
SRM 949e or its replacement, or other metal containing less
NOTE 6—Plutonium is not adsorbed on the resin if it is in the reduced
than 20 ppm of uranium in 5 mL of HCl (1+1), and dilute to
Pu(III) state.
100 mL with HCl (1+1).
29.5 Cool the solutions to room temperature and add 3
27.9 Sodium Cyanide Solution (50 g/L)—Dissolve5gof
drops of SnCl ·2 H O solution (700 g/L) to each beaker.
2 2
sodium cyanide (NaCN) in water and dilute to 100 mL with
NOTE 7—The stannous chloride prevents air oxidation of the Pu(III)
water.
during subsequent steps in the procedure.
27.10 Resin, Anion Exchange—Use Dowex 1-X2 anion
29.6 Add 13 mL of HCl (sp gr 1.19) to each beaker.
exchange resin, chloride form, 100 to 200 mesh, or equivalent
resin.
29.7 Transfer each solution to a separate ion exchange
column using five 1-mL portions of HCl (sp gr 1.19) to wash
27.11 Stannous Chloride Solution (700 g/L)—Dissolve 7 g
each beaker.
of stannous chloride (SnCl ·2 H O) in hydrochloric acid (HCl,
2 2
sp gr 1.19) and dilute to 10 mLwith HCl (sp gr 1.19). Prepare
29.8 Wash the Pu(III) from each column with six 5-mL
reagent fresh daily.
portions of HCl (sp gr 1.19).
27.12 Sulfuric Acid (1 + 2)—Dilute 1 volume of sulfuric
29.9 Next, elute the uranium from each column by washing
acid (H SO , sp gr 1.84) with 2 volumes of water.
2 4
each column with six 5-mLportions of 0.1 N HCl. Collect the
wash solutions from each column in a 50-mL beaker and
27.13 Sulfuric Acid (1 + 8)—Dilute 1 volume of sulfuric
evaporate to dryness on a hot plate under infrared lamps.
acid (H SO , sp gr 1.84) with 8 volumes of water.
2 4
29.10 Add 3 drops of HCl (sp gr 1.19) to dissolve each
27.14 Triethanolamine Buffer-Ethylenediamine-Tetraacetic
Acid Complexing Solution—Dissolve74.5goftriethanolamine residue and wash the sides of the beaker with water.
and 72 mg of ethylenediamine-tetraacetic acid, disodium salt
29.11 Add 4 drops of NaCN solutions (50 g/L) and 2 drops
(EDTA)in750mLofwaterand14.0mLofnitricacid(HNO ,
of phenolphthalein solution to each beaker; then add NH OH
spgr1.42)anddiluteto1Lwithwater.Allowsolutiontostand
(1+13) until the indicator remains slightly pink.
overnight before using.
29.12 Pipet 5 mL of triethanolamine buffer and 3.0 mL of
27.15 Uranium Standard Solution (20 mg/L)—Dissolve
Arsenazo I solution to each beaker.
23.60 mg of U O (NIST SRM 950b or its replacement), or
3 8
uranium oxide of equal purity, in 1 mL of HNO (1+2) and
29.13 Transfer each solution to a 25-mL volumetric flask
dilute to 1 L with H SO (1+8).
and dilute to volume with water.
2 4
29.14 Allow the solutions to stand 1 h for maximum color
28. Preparation of Ion Exchange Columns
development, and then measure the absorbance at 600 nm in
28.1 Wash 250 g of the anion exchange resin alternately
1-cm cells versus a reference solution prepared from the
with three 350-mL portions of HCl (sp gr 1.19) and three
reagents starting at 29.11.
350-mL portions of water. Allow the resin to remain in each
29.15 Calibration Curve:
solution for 30 min.
29.15.1 Process the results obtained in 29.14 in accordance
28.2 Fill each column to a height of 10 cm with ion
with the procedure described in 31.1 and 31.2.
exchange resin and rinse each column with 30 mL of HCl (sp
29.15.2 Each time samples are analyzed verify the calibra-
gr 1.19).
tion by processing duplicate aliquots of plutonium matrix
NOTE 5—Immediately before each analysis, rinse each column with 30 calibration solutions containing no uranium; also process a set
mL of HCl (sp gr 1.19) and remove any entrapped air from the column.
of duplicates that contain 5 mL each of uranium standard (20
mg/L) added to aliquots of plutonium matrix calibration
29. Calibration and Standardization
solution by the procedure given in 29.3 through 29.14.
29.1 Pipet ten 10-mL aliquots of plutonium matrix calibra- 29.15.3 Process the results obtained in 29.15.2 in accor-
tionsolution(7g/L)intoseparate50-mLbeakersandadd2mL dance with the procedure outlined in 31.3. If the individual
of H SO (1+2). calibration value disagrees at the 0.05 significance level with
2 4
C759 − 18
the value of the constant obtained from the complete calibra- 32. Calibration of Uranium Concentration
tion set, investigate and rectify the cause before proceeding
32.1 Calculate the uranium concentration in the sample, R,
with further analyses.
micrograms per gram Pu, as follows:
R 5 Y 2 B /AWC (6)
~ !
30. Procedure
where:
30.1 Prepare duplicate reagent blanks starting with 30.3.
R = micrograms U per gram plutonium,
30.2 Transfer a sample aliquot containing approximately 70
A, B = constants in linear calibration equation,
mg of plutonium weighed to 60.1 mg into a 50-mL beaker.
C = grams Pu per gram plutonium nitrate solution in
30.3 Add 5 mL of HCl (sp gr 1.19) to the beaker.
sample,
W = weight of sample aliquot, g, and
30.4 Evaporate the solution to near dryness slowly to avoid
Y = a−b=corrected absorbance of sample solution
loss of sample.
where:
NOTE 8—This eliminates excess nitrate which would prevent reduction
of the plutonium.
a = absorbance of sample solution, and
b = average absorbance of duplicate calibration blanks.
30.5 Proceed with the analysis as described in 29.3 through
29.14.
33. Precision and Bias
30.6 Calculate the concentration of uranium in micrograms
33.1 In the range from 300 to 1100 µg U/g Pu the standard
per gram of plutonium in accordance with instructions in
deviationis 6100µg/g;intherangefrom1500to3000µgU/g
Section 32.
Pu it is 650 µg/g.
31. Calculation of Calibration Factors
THORIUM BY THORIN SPECTROPHOTOMETRIC
31.1 Calculate the corrected absorbance value for each
TEST METHOD
standard solution as follows:
34. Scope
Y 5 r 2 s (3)
34.1 This test method covers the determination of 10 to 150
where:
µg of thorium per gram of plutonium in plutonium nitrate
Y = corrected absorbance value for standard,
solutions.
r = absorbance value of standard obtained in 29.14, and
s = average absorbance value obtained in 29.14 for the
35. Summary of Test Method
duplicate calibration blanks with no uranium added.
35.1 Lanthanum is added as a carrier and is precipitated
31.2 Use the least squares formulas and the data from 31.1
along with thorium as insoluble fluoride, while the plutonium
tocalculatevaluesof Aand Binthelinearcalibrationequation:
remains in solution and is decanted after centrifugation of the
Y 5 Ax1B, thatbestfitsthedata (4) sample. The thorium and lanthanum fluoride precipitate is
dissolved in perchloric acid, and the absorbance of the
where:
thorium-thorincomplexismeasuredatawavelengthof545nm
A, B = constants (B should be approximately zero),
versus a reference solution. The molar absorptivity of the
Y = corrected absorbance value from 31.1, and
colored complex is 15600 for thorium concentration in the
x = micrograms of uranium in the standard calibration
range from 5 to 70 µg Th/10 mL of the solution.
solution.
31.3 Calculate the individual calibration value for each 36. Interferences
standard solution processed simultaneously with each set of
36.1 Cations that form insoluble fluorides and colored
samples as follows:
complexes with thorin interfere in this test method.
A' 5 m/n (5)
37. Apparatus
where:
37.1 Infrared Heat Lamps, 250-W, borosilicate glass.
A' = individual calibration value for each standard solution,
37.2 Aluminum Heating Block—Drill a 150-mm high alu-
minum block to hold 16 12-mL centrifuge tubes and a
n = micrograms of uranium in the standard solution, and
m = corrected absorbance of standard=p−q thermometer. In use the block is heated to 220°C.
37.3 Platinum Stirring Rod, 1 mm in diameter by 160 mm
where
long.
p = absorbance for standard solution, and
q = average absorbance obtained from duplicate blank 37.4 Spectrophotometer, with matched cells having 10-mm
solutions.
light path.
31.4 Each individual value of A' should agree at the 0.05 37.5 Vacuum Transfer Device, approximately 150 mm long
significance level with the value of A obtained from the with a ⁄18 standard-taper ground-glass joint that fits a 10-mL
complete calibration set. volumetric flask.
C759 − 18
38. Reagents and Materials stirring rod; rinse the rod with HF (1+24) after each stirring.
After 5 min, centrifuge the tubes for 5 min.
38.1 Ammonium Peroxydisulfate ((NH ) S O ).
4 2 2 8
39.1.9 Withdraw the supernatant plutonium-containing so-
38.2 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
lution by means of vacuum and transfer to a plutonium residue
chloric acid (HCl).
bottle. Invert the tubes onto a tissue for 1 to 2 min; then draw
off to the residue bottle any liquid that has drained down the
38.3 Hydrofluoric Acid (1 + 24)—Dilute 1 volume of con-
inner wall of the tubes.
centratedhydrofluoricacid(HF,spgr1.15)with24volumesof
water and store in a polyethylene wash bottle. 39.1.10 Washtheprecipitatebyadding3mLofHF(1+24)
and mixing with the platinum rod. Rinse the platinum rod with
38.4 Hydrogen Peroxide (30 %)—Concentrated hydrogen
HF (1+24), wait 5 min, and centrifuge for 5 min. Repeat the
peroxide (H O ).
2 2
procedure in 39.1.9 and proceed to step 39.1.11.
38.5 Hydroxylamine Hydrochloride Solution (250 g/L)—
39.1.11 Add 1 mL of HClO (70 to 72%) to each tube and
Dissolve 25 g of hydroxylamine hydrochloride (NH OH·HCl)
2 place the tubes in the heated aluminum heating apparatus for
in water and dilute to 100 mL with water.
30 min.
39.1.12 Remove the tubes, cool, and add HClO (70 to
38.6 Lanthanum Nitrate Solution (10 g La/L)—Dissolve 4
72%) to adjust the volume in each tube to 0.5 mL.
3.12 g of lanthanum nitrate (La(NO ) ·6 H O) in water and
3 3 2
39.1.13 Transfer each solution to a 10-mL volumetric flask
dilute to 100 mL with water.
usingthevacuumtransferdevicewiththree2-mLwaterrinses;
38.7 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
then add 0.5 mL of NH OH·HCl solution to each flask.
(HNO ).
39.1.14 Prepare a reference solution by adding 0.5 mL of
38.8 Perchloric Acid (70 to 72 %)—Concentratedperchloric
HClO (70 to 72%), 0.5 mL of NH OH·HCl solution (250
4 2
acid (HClO ).
g/L), and 6 mL of water to a 10-mL volumetric flask.
39.1.15 Place the flasks on a steam bath for 30 min.
38.9 Silver Nitrate Solution (2.5 g/L)—Dissolve 250 mg of
39.1.16 Remove the flasks from the steam bath, cool, and
silver nitrate (AgNO ) in water and dilute to 100 mL with
add 1 mL of Thorin solution to each flask. Dilute to volume
water. Store solution in an amber bottle.
with water, stopper, and shake.
38.10 Sulfuric Acid (1 + 35)—Add 1 volume of concen-
39.1.17 Measure the absorbance of the solutions in 10-mm
tratedsulfuricacid(H SO ,spgr1.84)to35volumesofwater.
2 4
cells versus the reference solution at a wavelength of 545 nm.
38.11 Thorin Solution (1 g/L)—Dissolve1gof thorin
39.1.18 Process the data obtained in 39.1.17 in accordance
o-(2-hydroxy-3,6-disulfo-1-naphthylazo) benzenearsonic acid
with the procedure described in 41.1.
disodium salt in water and dilute to 1 L.
39.2 Checking Calibration Curve:
38.12 Thorium Standard Solution (20.00 mg/L)—Dissolve
39.2.1 Each time a set of samples is analyzed verify the
20.00 mg of high-purity thorium as the metal, oxide, or nitrate
procedure and calibration factor by processing two 2-mL
inHCl(spgr1.19)andH O (30%).Add83mLofHClO (70
thorium standards and two blank solutions (with no thorium
2 2 4
to 72%) and dilute to 1 L with water. added) in accordance with the instructions in 39.1.2 through
39.1.17.
39. Calibration and Standardization 39.2.2 Process the data obtained in 39.2.1 in accordance
with the procedures described in 39.2. If an individual calibra-
39.1 Reference Standards and Blanks:
tion value disagrees at the 0.05 significance level with the
39.1.1 Pipet 1.00 mL of thorium standard (20 mg/L) into
value of the constant obtained from the complete calibration
each of two 20-mL beakers, 2.00 mL into each of 2 more
set, investigate and rectify the cause of the difficulty before
beakers and 3.00 mL into each of a third pair of beakers.
proceeding with further analyses.
39.1.2 To two additional 20-mL beakers and to each of the
solutions from 39.1.1, add 1 mL of HNO (sp gr 1.42) and 2
40. Procedure
mL of HClO (70 to 72%).
40.1 Transfer a weighed aliquot of sample containing from
39.1.3 Evaporate each solution to approximately 2 mLon a
5to70µgofthoriumandnogreaterthan500mgofplutonium
steam bath; then continue the evaporation to dryness under
intoa20-mLbeakerandproceedwiththeanalysisasdescribed
infrared lamps on a hot plate.
in 39.1.2 through 39.1.17.
39.1.4 Remove the beakers from the hot plate, and dissolve
each residue in approximately 2 mL of H SO (1+35), dis-
40.2 Calculatethethoriumconcentrationinaccordancewith
2 4
pensed from a polyethylene wash bottle.
the procedure described in 41.3.
39.1.5 Transfer each solution to a 12-mL centrifuge tubing
41. Calculation
using three 2-mL rinses of H SO (1+35).
2 4
39.1.6 Add 5 drops of La(NO ) ·6 H O (10 g/L) solution
3 3 2 41.1 Equation for Calibration Data:
and 0.1 mL ofAgNO solution (2.5 g/L) and approximately 1
3 41.1.1 Calculate the corrected absorbance value for each
gof(NH ) S O to each centrifuge tube.
4 2 2 8
standard calibration solution as follows:
39.1.7 Heat the tubes in a steam bath for 15 min.
Y 5 r 2 s (7)
39.1.8 Removethetubesfromthesteambath,cool,andadd
1 mL of HF (sp gr 1.15). Stir the mixture with a platinum where:
C759 − 18
IRON BY 1,10-PHENANTHROLINE
Y = corrected absorbance value for the standard calibration
SPECTROPHOTOMETRIC TEST METHOD
solution,
r = absorbance value obtained in 39.1.17 for the standard
43. Scope
calibration solution, and
s = average absorbance value obtained in 39.1.17 for the
43.1 This test method covers the determination of micro-
duplicate calibration blanks.
gram quantities of iron in plutonium nitrate solutions.
41.1.2 Use least squares formulas and the data from 41.1.1
44. Summary of Test Method
tocalculatevaluesof Aand Binthelinearcalibrationequation:
44.1 Ferricionisreducedtoferrousionwithhydroxylamine
Y 5 Ax1B, thatbestfitsthedata (8)
hydrochloride. Solutions of 1,10-phenanthroline and acetate
buffer are added and the pH adjusted to 3.5 to 4.5. The
where:
+2
absorbance of the red-orange complex [(C H N ) Fe] is
12 8 2 3
A, B = constants (B should be approximately zero),
read at 508 nm against a sample blank containing all of the
Y = corrected absorbance from 41.1.1, and
reagents except the 1,10-phenanthroline (6).
x = micrograms thorium in the standard calibration solu-
tion.
45. Interferences
41.2 Individual Calibration Values:
45.1 Plutonium must be reduced to Pu(III) to avoid causing
41.2.1 Calculate the individual calibration value for each
interference.
standard solution processed with the samples as follows:
45.2 Silver and bismuth form precipitates.
A' 5 m/n (9)
45.3 Tolerance limits for 2 µg/mL Fe for elements that
interfere in this determination are as follows (7):
where:
A' = individual calibration value for each standard solution, Element µg/mL Element µg/mL
Cd 50 Mo 100
n = micrograms of thorium in standard solution,
Hg(I) 10 Zr 10
m = corrected absorbance value for standard solution p−q
Zn 10 Cr(VI) 25
W5 V O 50
2 5
Ni 2 Mn(II) 200
Co 10 U O 400
3 8
where:
Cu 10 P O 20
2 5
p = absorbance value from standard solution, and
Sn(II) 20 F 500
Pu(IV) 300 Np(IV) 100
q = average absorbance of duplicate blank solutions from
39.1.17.
46. Apparatus
41.2.2 Each individual A' should agree at the 0.05 signifi-
46.1 Spectrophotometer, visible range with matched 10-mm
cance level with the value of A obtained from the complete
cells.
calibration set.
47. Reagents and Materials
41.3 Determine the thorium concentration of the sample as
47.1 Acetate Buffer Solution—Dissolve 410 g of sodium
follows:
acetate, (Na C H O ) in water, add 287 mL of glacial acetic
2 2 3 2
Th, µg/g Pu 5 R 5 ~Y 2 B!/AWC (10)
acid, and dilute to 1 L with water.
where:
47.2 Ammonium Hydroxide (1 + 9)—Dilute 1 volume of
A and B = constants in the linear calibration equation,
NH OH (sp gr 0.9) with 9 volumes of water.
W = sample mass, g,
47.3 Hydrochloric Acid (1 + 9)—Dilute 1 volume of HCl
C = grams Pu per gram of sample, and
(sp gr 1.19) with 9 volumes of water.
Y = a−b=corrected absorbance of sample solution
47.4 Hydroxylamine Hydrochloride Solution (104 g/L)—
where:
Dissolve104gofhydroxylaminehydrochloride(NH OH·HCl)
a = absorbance value for sample solution, and
in water and dilute to 1 L with water.
b = average absorbance value from the duplicate reagent
47.5 Iron Standard (100 µg Fe/mL)—Carefullydissolve100
blanks described in 39.2.1.
mgofhigh-purityironwirein165mLofHCl(1+1),cool,and
dilute to 1 L with water.
42. Precision and Bias
47.6 1,10-Phenanthroline Solution (0.2 weight/volume %)—
42.1 The relative standard deviation is less than 2% at
Dissolve2gof 1,10-phenanthroline in water and dilute to 1 L
thorium concentrations between 66 and 144 µg/g Pu, 4% at a
with water.
concentration of 34 µg/g Pu, and 11% at a concentration of 10
µg/g Pu.
48. Procedure
42.2 The average value for thorium found in 91 measure-
48.1 Transfer an aliquot of sample that contains 5 to 75 µg
ments of 5 to 70 µg of thorium was 99 61%. of iron to a 30-mL beaker and add 10 mL acetate buffer
C759 − 18
NOTE 10—Save a portion of the distillate to use for the fluoride
solution and 1 mL of hydroxylamine hydrochloride solution.
determination.
Let solution stand for 10 min.
48.2 Add 1 mL of 1,10-phenanthroline solution and adjust
53. Interferences
the pH of the solution to the range from 3.5 to 4.5 with HCl
53.1 Iodide, bromide, cyanide, and thiocyanate ions inter-
(1+9)orNH OH.
fere. Nitrite interference is eliminated by use of sulfamic acid.
48.3 Transfer the solution to a 25-mLvolumetric flask. Use
water to wash the beaker and to dilute to volume. Stopper the
54. Apparatus
flask and mix thoroughly.
54.1 Steam Distillation Apparatus, including a steam gen-
48.4 After 10 min, measure the absorbance of the sample
erator and heating mantles.
aliquot against a sample blank that contains all of the reagents,
54.2 Spectrophotometer and Matched 10-mm Cells.
except 1,10-phenanthroline, at a wavelength of 508 nm.
NOTE9—Forsamplealiquotsthatcontainironintherangeof5µg,cells
55. Reagents and Materials
of 5-cm length or longer should be used.
55.1 Chloride Standard Solution (5 µg Cl/mL)—Prepare a
48.5 Prepare a calibration curve by adding to separate
stock solution,A, Cl=500 µg⁄mL, by dissolving 824.4 mg of
30-mLbeakers,containing10mLofacetatebuffersolutionand
dried NaCl in water and diluting to 1 L. Prepare chloride
1 mL of hydroxylamine hydrochloride solution, the following
standard, 5 µg Cl/mL, by diluting 10 mLof stock solutionAto
amounts of iron standard: 0, 50, 100, 250, and 500 µL of iron
1 L with water.
standard solution (100 µg Fe/mL). Follow the steps given in
55.2 Ferric Ammonium Sulfate Solution (0.25 M)—
48.2 through 48.4 of the procedure; then plot the absorbance
Dissolve 12 g FeNH (SO ) ·12 HOinH SO (5+95) and
versus the micrograms of iron per 25 mL final volume of the
4 4 2 2 2 4
dilute to 100 mL with H SO (5+95).
solution. 2 4
55.3 Ferrous Ammonium Sulfate (0.2 M) Sulfamic Acid (0.5
49. Calculation
M) Solution—Dissolve 78.4 g of Fe(NH ) (SO ) ·6 H O and
4 2 4 2 2
48.6gofNH SOHinH SO (5+95) and dilute to 1 L with
49.1 Calculate the iron in micrograms per gram of pluto-
2 3 2 4
H SO (5+95).
nium as follows:
2 4
55.4 Mercuric Thiocyanate Solution (saturated)—Add Hg-
Fe, µg/g Pu 5 C/PW (11)
(SCN) to 90% ethyl alcohol until the solution is saturated.
where:
C = micrograms of Fe from calibration curve,
56. Procedure
W = weight of sample, g, and
56.1 Transfer 25 mL of acid mixture consisting of 0.2 M
P = Pu, g/g of sample.
ferrous ammonium sulfate-0.5 M sulfamic acid solution, phos-
phoric acid, and sulfuric acid mixed in the ratio1+1+2.5, to
50. Precision and Bias
a steam distillation flask and steam distill at 140°C until 100
50.1 The relative standard deviation is 6%.
mL of distillate is collected. Retain this solution for use as a
reagent blank.
IMPURITIES BY ICP-AES
(Cationic impurities may be determined using Test Method
56.2 Transfer an accurately weighed aliquot of plutonium
C1432 (Impurities by ICP-AES) with appropriate sample
nitrate solution that contains approximately 500 mg of pluto-
preparation and instrumentation.
nium to a steam distillation flask and add 25 mL of acid
mixture as described in 56.1. Steam distill at 140°C until 100
CHLORIDE BY THIOCYANATE
mL of distillate is collected.
SPECTROPHOTOMETRIC TEST METHOD
56.3 Transfer up to 6 mL of sample distillate, and 6 mL of
reagent blank distillate, to separate 10-mL volumetric flasks.
51. Scope
To each flask, add 2 mL of 0.25 M ferric ammonium sulfate
51.1 This test method (8) is used to determine chloride in
solution, 2 mLof saturated mercuric thiocyanate solution, and
plutonium nitrate solution.
dilute to volume with water solution and mix.
52. Summary of Test Method 56.4 After 10 min, transfer the solutions to 1-cm cells and
measure the absorbance of the sample versusthe reagent blank
52.1 After the sample aliquot is mixed with a solution
at a wavelength of 460 nm.
containing ferrous ammonium sulfate, sulfamic acid, phos-
phoric acid, and sulfuric acid, the chloride is steam distilled at 56.5 Prepareacalibrationcurvebyadding0,0.5,1,2.5,and
a temperature of 140°C (Note 10). An aliquot of the distillate 4 mL of the chloride standard (5 µg Cl/mL) to 10-mL
is mixed with ferric ammonium sulfate and mercuric thiocya- volumetricflasksanddilutetoabout5mLwithwatersolution.
nate solutions. Thiocyanate ion is released in direct proportion Add 2 mL of 0.25 M ferric ammonium sulfate solution and 2
to the chloride ion concentration. The absorbance of the mLofmercuricthiocyanatesolution,mix,anddilutetovolume
resulting red-brown ferric thiocyanate complex is read at 460 with water solution. Mix solutions again and after 10 min
nm against a reagent blank. transfer the solution to 1-cm absorption cells and read the
C759 − 18
absorbance versus a reagent blank at a wavelength of 460 nm. 1.000 mg F/mL, into a 1-L volumetric flask and dilute to
Plot the micrograms of Cl per 10 mL of solution versus the volume with water to prepare the fluoride standard, 10 µg
absorbance reading. F/mL.
64. Procedure
57. Calculation
64.1 Transfer 20-mL aliquots of the sample and of the
57.1 Calculate the micrograms of Cl per gram of plutonium
reagent blank distillates, which were prepared during the
as follows:
determination of chloride, to 50-mLbeakers and adjust the pH
Cl, µg/g Pu 5 CD/WP (12)
to 5.0 to 5.2 by the addition of fluoride-free NaOH solution or
HCl. Dilute these solutions to 25 mL.
where:
C = micrograms Cl from calibration curve,
64.2 Transfer 8-mL aliquots of the solutions prepared in
D = dilution factor=distillate, mL/aliquot of distillate,
64.1 to 10-mL flasks and add 2 mL of Amadac F reagent (0.1
mL,
g/L) to each solution and mix.
W = weight of sample, g, and
64.3 Allow the solutions to stand 1 h; then measure the
P = Pu, g/g of sample.
absorbance of the blue-colored complex in the sample versus
the reagent blank solution at a wavelength of 620 nm in 1-cm
58. Precision and Bias
cells.
58.1 Theprecisionandbiasofthistestmethodis100 65%
64.4 To prepare a calibration curve, pipet 0, 50, 100, 200,
with a sodium chloride matrix. No plutonium standard is
500, and 1000-µLaliquots of the fluoride standard solution (10
available.
µg F/mL) into separate 10-mLvolumetric flasks.Add 2 mLof
AmadacFsolution(0.1g/L)toeachflaskanddilutetovolume.
FLUORIDE BY DISTILLATION-
Mix, allow solutions to stand in the dark for 1 h, and measure
SPECTROPHOTOMETRIC TEST METHOD
the absorbance of each in 1-cm cells versus a reagent blank at
59. Scope awavelengthof620nm.Plotthemicrogramsoffluorideinthe
10-mL volume of solution versus the absorbance.
59.1 This test method covers the determination of micro-
quantities of fluoride in plutonium nitrate solutions.
65. Calculation
65.1 Calculate the fluoride in micrograms per gram of
60. Summary of Test Method
plutonium as follows:
60.1 Fluoride is separated from the plutonium nitrate dis-
F, µg/g Pu 5 CD/WP (13)
solved in a mixture of phosphoric and sulfuric acid by steam
distillation at 140 6 5°C (Note 11). The fluoride, in an aliquot
where:
of the distillate, is complexed with Amadac F and the absor-
C = micrograms of F from calibration curve,
bance of the blue-colored complex is read in 1-cm cells versus
D = dilution factor= V V /A A
...

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: C759 − 10 C759 − 18
Standard Test Methods for
Chemical, Mass Spectrometric, Spectrochemical, Nuclear,
and Radiochemical Analysis of Nuclear-Grade Plutonium
Nitrate Solutions
This standard is issued under the fixed designation C759; 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 These test methods cover procedures for the chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical
analysis of nuclear-grade plutonium nitrate solutions to determine compliance with specifications.
1.2 The analytical procedures appear in the following order:
Sections
Plutonium by Controlled-Potential Coulometry
Plutonium by Amperometric Titration with Iron(II)
Plutonium by Diode Array Spectrophotometry
Free Acid by Titration in an Oxalate Solution 8 to 15
Free Acid by Iodate Precipitation-Potentiometric Titration 16 to 22
Test Method
Uranium by Arsenazo I Spectrophotometric Test Method 23 to 33
Thorium by Thorin Spectrophotometric Test Method 34 to 42
Iron by 1,10-Phenanthroline Spectrophotometric Test Method 43 to 50
Impurities by ICP-AES
Chloride by Thiocyanate Spectrophotometric Test Method 51 to 58
Fluoride by Distillation-Spectrophotometric Test Method 59 to 66
Sulfate by Barium Sulfate Turbidimetric Test Method 67 to 74
Isotopic Composition by Mass Spectrometry 75 to 76
Plutonium —238 Isotopic Abundance by Alpha Spectrometry
Plutonium-238 Isotopic Abundance by Alpha Spectrometry
Americium-241 by Extraction and Gamma Counting 77 to 85
Americium-241 by Gamma Counting 86 to 94
Gamma-Emitting Fission Products, Uranium, and Thorium by 94 to 102
Gamma-Ray Spectroscopy
Rare Earths by Copper Spark Spectrochemical Test Method 103 to 105
Tungsten, Niobium (Columbium), and Tantalum by Spectro 106 to 114
chemical Test Method
Tungsten, Niobium (Columbium), and Tantalum by Spectro- 106 to 114
chemical Test Method
Sample Preparation for Spectrographic Analysis for General 115 to 118
Impurities
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific safeguard and safety hazard statements, see Section 6.
1.5 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.
These test methods are under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and are the direct responsibility of Subcommittee C26.05 on Methods
of Test.
Current edition approved June 1, 2010Sept. 1, 2018. Published July 2010October 2018. Originally approved in 1973. Last previous edition approved in 20042010 as
C759 – 04.C759 – 10. DOI: 10.1520/C0759-10.10.1520/C0759-18.
Discontinued as of November 15, 1992.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C759 − 18
2. Referenced Documents
2.1 ASTM Standards:
C697 Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Plutonium Dioxide
Powders and Pellets
C852C852/C852M Guide for Design Criteria for Plutonium Gloveboxes
C859 Terminology Relating to Nuclear Materials
C1009 Guide for Establishing and Maintaining a Quality Assurance Program for Analytical Laboratories Within the Nuclear
Industry
C1068 Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Industry
C1108 Test Method for Plutonium by Controlled-Potential Coulometry
C1128 Guide for Preparation of Working Reference Materials for Use in Analysis of Nuclear Fuel Cycle Materials
C1156 Guide for Establishing Calibration for a Measurement Method Used to Analyze Nuclear Fuel Cycle Materials
C1165 Test Method for Determining Plutonium by Controlled-Potential Coulometry in H SO at a Platinum Working Electrode
2 4
C1206 Test Method for Plutonium by Iron (II)/Chromium (VI) Amperometric Titration (Withdrawn 2015)
C1210 Guide for Establishing a Measurement System Quality Control Program for Analytical Chemistry Laboratories Within
the Nuclear Industry
C1235 Test Method for Plutonium by Titanium(III)/Cerium(IV) Titration (Withdrawn 2005)
C1268 Test Method for Quantitative Determination of Am in Plutonium by Gamma-Ray Spectrometry
C1297 Guide for Qualification of Laboratory Analysts for the Analysis of Nuclear Fuel Cycle Materials
C1307 Test Method for Plutonium Assay by Plutonium (III) Diode Array Spectrophotometry
C1415 Test Method for Pu Isotopic Abundance By Alpha Spectrometry
C1432 Test Method for Determination of Impurities in Plutonium: Acid Dissolution, Ion Exchange Matrix Separation, and
Inductively Coupled Plasma-Atomic Emission Spectroscopic (ICP/AES) Analysis
D1193 Specification for Reagent Water
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E115 Practice for Photographic Processing in Optical Emission Spectrographic Analysis (Withdrawn 2002)
E116 Practice for Photographic Photometry in Spectrochemical Analysis (Withdrawn 2002)
3. Terminology
3.1 For definitions of terms used in this test method but not defined herein, refer to Terminology C859.
4. Significance and Use
4.1 These test methods are designed to show whether a given material meets the purchaser’s specifications.
4.1.1 An assay is performed to determine whether the material has the specified plutonium content.
4.1.2 Determination of the isotopic content of the plutonium in the plutonium-nitrate solution is made to establish whether the
effective fissile content is in compliance with the purchaser’s specifications.
4.1.3 Impurity content is determined by a variety of methods to ensure that the maximum concentration limit of specified
impurities is not exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC).
4.2 Fitness for Purpose of Safeguards and Nuclear Safety Applications—Methods intended for use in safeguards and nuclear
safety applications shall meet the requirements specified by Guide C1068 for use in such applications.
4. Committee C26 Safeguards Statement
4.1 The material (plutonium nitrate) to which these test methods apply is subject to nuclear safeguards regulations governing
its possession and use. The following analytical procedures in these test methods have been designated as technically acceptable
for generating safeguards accountability measurement data: Plutonium by Controlled-Potential Coulometry; Plutonium by
Amperometric Titration with Iron(II); Plutonium by Diode Array Spectrophotometry and Isotopic Composition by Mass
Spectrometry.
4.2 When used in conjunction with appropriate Certified Reference Materials (CRMs), these procedures can demonstrate
traceability to the national measurement base. However, adherence to these procedures does not automatically guarantee regulatory
acceptance of the resulting safeguards measurements. It remains the sole responsibility of the user of these test methods to assure
that their application to safeguards has the approval of the proper regulatory authorities.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standardsvolume information, refer to the standard’s Document Summary page on the ASTM website
The last approved version of this historical standard is referenced on www.astm.org.
C759 − 18
5. Reagents and Materials
5.1 Purity of Reagents—Reagent grade chemicals shall be used in all test methods. 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 it is first ascertained that the reagent is of sufficiently
high purity to permit its use without lessening the accuracy of the determination.
5.2 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to
Specification D1193.
6. Safety Hazards
6.1 Since plutonium bearing materials are radioactive and toxic, adequate laboratory facilities, gloved boxes, fume hoods, etc.,
along with safe techniques, must be used in handling samples containing these materials. A detailed discussion of all the
precautions necessary is beyond the scope of these test methods; however, personnel who handle these materials should be familiar
with such safe handling practices as are given in Guide C852C852/C852M and in Refs (1) through (2).
6.2 Adequate laboratory facilities, such as fume hoods and controlled ventilation, along with safe techniques, must be used in
this procedure. Extreme care should be exercised in using hydrofluoric and other hot, concentrated acids. Use of proper gloves is
recommended. Refer to the laboratory’s chemical hygiene plan and other applicable guidance for handling chemical and
radioactive materials and for the management of radioactive, mixed, and hazardous waste.
6.3 Hydrofluoric acid is a highly corrosive acid that can severely burn skin, eyes, and mucous membranes. Hydrofluoric acid
is similar to other acids in that the initial extent of a burn depends on the concentration, the temperature, and the duration of contact
with the acid. Hydrofluoric acid differs from other acids because the fluoride ion readily penetrates the skin, causing destruction
of deep tissue layers. Unlike other acids that are rapidly neutralized, hydrofluoric acid reactions with tissue may continue for days
if left untreated. Due to the serious consequence of hydrofluoric acid burns, prevention of exposure or injury of personnel is the
primary goal. Utilization of appropriate laboratory controls (hoods) and wearing adequate personal protective equipment to protect
from skin and eye contact is essential.
7. Sampling
7.1 A sample representative of the lot shall be taken from each lot into a container or multiple containers that are of such
composition that corrosion, chemical change, radiolytic decomposition products, and method of loading or sealing will not disturb
the chemical or physical properties of the sample. (A flame-sealed quartz vial that is suitable for accommodating pressure resulting
from radiolytic decomposition is generally considered to be an acceptable sample container.)
7.2 Sample size shall be sufficient to perform the following:
7.2.1 Assay and acceptance tests at the seller’s plant,
7.2.2 Assay and acceptance tests at the purchaser’s plant, and
7.2.3 Referee tests in the event they become necessary.
7.3 All samples shall be identified clearly, including the seller’s lot number.
7.3.1 A lot is defined as any quantity of aqueous plutonium nitrate solution that is uniform in isotopic, chemical, and physical
characteristics by virtue of having been mixed in such a manner as to be thoroughly homogeneous.
7.3.2 All containers used for a lot shall be identified positively as containing material from a particular homogeneous solution.
Reagent Chemicals, American Chemical 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. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
The boldface numbers in parentheses refer to the list of references at the end of these test methods.
C759 − 18
PLUTONIUM BY CONTROLLED-POTENTIAL COULOMETRY
(This test method was discontinued in 1992 and replaced by Test Method C1165.)
PLUTONIUM BY CONTROLLED-POTENTIAL COULOMETRY
(With appropriate sample preparation, controlled-potential coulometric measurement as described in Test Method C1108 may
be used for plutonium determination.)
PLUTONIUM BY AMPEROMETRIC TITRATION WITH IRON(II)
(This test method was discontinued in 1992 and replaced by Test Method C1206.)
TEST METHOD FOR PLUTONIUM ASSAY BY PLUTONIUM(III) DIODE ARRAY SPECTROPHOTOMETRY
(With appropriate sample preparation, the measurement described in Test Method C1307 may be used for plutonium determi-
nation.)
FREE ACID BY TITRATION IN AN OXALATE SOLUTION
8. Scope
8.1 This test method covers the determination of free acid in plutonium nitrate solutions (3, 4).
8. Scope
8.1 This test method covers the determination of free acid in plutonium nitrate solutions (3, 4).
9. Summary of Test Method
9.1 Free acid is determined by titrating an aliquot of sample, which contains an excess of ammonium oxalate added to complex
the plutonium, back to the original pH of the ammonium oxalate solution with standard sodium hydroxide solution. Micropipets
and microburets are required to measure the small volume of sample and titrant used.
10. Interferences
10.1 Any metal ions not complexed by oxalate which form precipitates at the pH of the end point of the titration will cause
interference in this test method.
NOTE 1—A “rule of thumb” is that 1 mL of saturated ammonium oxalate solution will complex 6.4 mg of plutonium.
11. Apparatus
11.1 Magnetic Stirrer.
11.2 Microburet.
11.3 Micropipets.
11.4 pH Meter.
12. Reagents and Materials
12.1 Ammonium Oxalate Solution, saturated.
12.2 Nitric Acid (3.50 N)—Prepare solution by diluting concentrated nitric acid (HNO , sp gr 1.42) with water. Standardize by
titrating 0.500-mL aliquots with 0.100 N NaOH solution.
12.3 Sodium Hydroxide Solution (0.100 N)—Prepare and standardize in accordance with Practices E50.
13. Procedure
13.1 Transfer 1.0 mL of saturated ammonium oxalate solution to a small vial and dilute to about 2 mL with water.
13.2 Add a stirring bar and insert the electrodes and start stirrer. When the pH value becomes stable, record the value as the
pH of reagent.
NOTE 2—Normally, the pH value for the saturated solution is approximately 6.4.
13.3 Add 20 μL of sample to the vial, rinse the pipet thoroughly with water, and stir the solution for 1 min.
13.4 Titrate with 0.100 N NaOH solution to within one pH unit of the end point; then, by adding successively smaller
increments, titrate to the pH of the ammonium oxalate reagent and record the volume of titrant.
NOTE 3—Allow time for the pH reading to stabilize between additions of titrant as the end point is approached.
13.5 Make a daily check of the system by adding 20 μL of 3.50 N HNO to a sample that has already been titrated to the end
point and titrate with standard 0.100 N NaOH solution back to the same pH.
C759 − 18
14. Calculation
+
14.1 Calculate the free acid (H , N) as follows:
H , N 5 A 3N /V (1)
~ !
where:
A = microlitres of standard NaOH solution required to titrate sample,
N = normality of NaOH standard solution, and
V = volume of sample, μL.
15. Precision and Bias
15.1 Precision—Of individual results, 65 % at the 95 % confidence level.
15.2 Bias—99.4 %.
FREE ACID BY IODATE PRECIPITATION-POTENTIOMETRIC TITRATION TEST METHOD
16. Scope
16.1 This test method covers the determination of free acid in strong acid solutions of plutonium nitrate.
16. Scope
16.1 This test method covers the determination of free acid in strong acid solutions of plutonium nitrate.
17. Summary of Test Method
17.1 Free acid is determined by potentiometric titration with standard sodium hydroxide solution after precipitation and
subsequent removal of plutonium (up to 50 mg) as plutonium iodate.
18. Interferences
18.1 Any hydrolyzable ions that are not precipitated with iodate will interfere.
19. Reagents and Materials
19.1 Hydrochloric Acid (sp gr 1.19)—Concentrated hydrochloric acid (HCl).
19.2 Nitric Acid (1 + 14)—Dilute 14 volumes of water with 1 volume of concentrated nitric acid (HNO , sp gr 1.42).
19.3 Potassium Iodate (0.3 M)—Dissolve 64.2 g of potassium iodate (KIO ) in 900 mL of water, adjust the pH to 4.3 by adding
HNO (1 + 14), and dilute to 1 L with water.
19.4 Sodium Hydroxide (0.3 M)—Prepare and standardize in accordance with Practices E50 after making the following
alterations: Use 15 mL of the NaOH solution (50 g/50 mL), and in step 42.2, transfer 1.200 g of National Institute for Standards
and Technology (NIST) potassium acid phthalate SRM 84 h or its replacement to a 250-mL Erlenmeyer flask instead of 0.4000
g.
20. Procedure
20.1 Pipet 50 mL of KIO (0.3 M) into a beaker and stir while adding an aliquot of sample solution containing no greater than
50 mg of plutonium.
20.2 After precipitation is complete, filter the solution through either a medium porosity glass frit or a fine textured acid-washed
filter paper and collect the filtrate in a beaker.
20.3 Wash the precipitate with two 25-mL portions of 0.3 M KIO solution, and combine the washings with the filtrate from
step 20.2.
20.4 Dissolve the precipitate in HNO (sp gr 1.42) or HCl (sp gr 1.19) and transfer to a residue bottle.
20.5 Transfer the sample from 20.3 to the titration apparatus, position the electrodes and a magnetic stirring bar in the solution,
and start the stirrer.
20.6 Titrate the free acid in the solution by adding the 0.3 M NaOH solution from a 5-mL buret and plot the titration curve (pH
versus mL NaOH solution).
20.7 Determine the end point of the titration from the midpoint of the inflection on the titration curve and record the volume
of 0.3 M NaOH solutions by the steps given in 20.5 through 20.7 of the procedure.
21. Calculation
+
21.1 Calculate the free acid (H , N) as follows:
H , N 5 V 2 V N/S (2)
~ !
s b
C759 − 18
where:
N = normality of NaOH solution,
V = millilitres of NaOH solution to titrate sample aliquot,
s
V = millilitres of NaOH solution to titrate reagent blank, and
b
S = millilitres of sample aliquot.
22. Precision and Bias
22.1 The relative standard deviation, based on 49 titrations, is 0.9 % for aliquots of sample containing a minimum of 0.2
milliequivalents of acid.
22.2 Between 99 and 100 % of the free acid in standard plutonium (IV) solutions has been measured by this procedure;
however, when the plutonium was in the (III) oxidation state, the results showed a negative bias of as much as 8 % (5).
URANIUM BY ARSENAZO I SPECTROPHOTOMETRIC TEST METHOD
23. Scope
23.1 This test method covers the determination of uranium in the range from 300 to 3000 μg/g of plutonium in plutonium nitrate
solutions.
23. Scope
23.1 This test method covers the determination of uranium in the range from 300 to 3000 μg/g of plutonium in plutonium nitrate
solutions.
24. Summary of Test Method
24.1 Plutonium is reduced to Pu(III) in HCl (1 + 1) solution with hydroxylamine hydrochloride. The uranium and plutonium
are then separated by anion exchange, and the uranium is determined by measuring the absorbance of the U(VI)-Arsenazo I
complex in a 1-cm cell at a wavelength of 600 nm versus a reagent blank.
25. Interference
25.1 Iron at 500 μg/g of plutonium is the most likely interference in this test method.
26. Apparatus
26.1 Columns, ion exchange, 1 by 10 cm. Columns can be made by sealing a 1-cm diameter filtering tube with a coarse glass
frit to the bottom of a 40-mL centrifuge tube and cutting the tube off diagonally just below the frit.
26.2 Spectrophotometer and 1-cm Matched Cells.
27. Reagents and Materials
27.1 Ammonium Hydroxide (1 + 13)—Dilute 1 volume of concentrated ammonium hydroxide (NH OH, sp gr 0.90) with 13
volumes of water.
27.2 Arsenazo I Reagent (0.500 g/L)—Dissolve 250 mg of the purified reagent [(3-2-arsonophenylazo)-4,5-dihydroxy-2,7
naphthalenedisulfonic acid, disodium salt] in water and dilute to 500 mL with water.
NOTE 4—Purify reagents as follows: To a saturated aqueous solution of Arsenazo I, add an equal volume of HCl (sp gr 1.19), filter the orange
precipitate, wash with acetonitrile, and dry at 100°C for 1 h.
27.3 Hydrochloric Acid (0.1 N)—To prepare, dilute 8.3 mL of hydrochloric acid (HCl, sp gr 1.19) to 1 L with water.
27.4 Hydrochloric Acid (1 + 1)—To prepare, dilute 500 mL of hydrochloric acid (HCl, sp gr 1.19) to 1 L with water.
27.5 Hydroxylamine Hydrochloride Solution (100 g/L)—Dissolve 10 g of (NH OH·HCl) in water and dilute to 100 mL with
water.
27.6 Nitric Acid (1 + 2)—Dilute 100 mL of nitric acid (HNO , sp gr 1.42) to 300 mL with water.
27.7 Phenolphthalein Solution (0.25 g/L)—Dissolve 25 mg of phenolphthalein in a water-ethanol (1 + 1) solution and dilute to
100 mL with the water-ethanol solution.
27.8 Plutonium Matrix Calibration Solution (7 g/L)—Dissolve approximately 700 mg of plutonium metal, NIST SRM 949e or
its replacement, or other metal containing less than 20 ppm of uranium in 5 mL of HCl (1 + 1), and dilute to 100 mL with HCl
(1 + 1).
27.9 Sodium Cyanide Solution (50 g/L)—Dissolve 5 g of sodium cyanide (NaCN) in water and dilute to 100 mL with water.
27.10 Resin, Anion Exchange—Use Dowex 1-X2 anion exchange resin, chloride form, 100 to 200 mesh, or equivalent resin.
C759 − 18
27.11 Stannous Chloride Solution (700 g/L)—Dissolve 7 g of stannous chloride (SnCl ·2 H O) in hydrochloric acid (HCl, sp
2 2
gr 1.19) and dilute to 10 mL with HCl (sp gr 1.19). Prepare reagent fresh daily.
27.12 Sulfuric Acid (1 + 2)—Dilute 1 volume of sulfuric acid (H SO , sp gr 1.84) with 2 volumes of water.
2 4
27.13 Sulfuric Acid (1 + 8)—Dilute 1 volume of sulfuric acid (H SO , sp gr 1.84) with 8 volumes of water.
2 4
27.14 Triethanolamine Buffer-Ethylenediamine-Tetraacetic Acid Complexing Solution—Dissolve 74.5 g of triethanolamine and
72 mg of ethylenediamine-tetraacetic acid, disodium salt (EDTA) in 750 mL of water and 14.0 mL of nitric acid (HNO , sp gr 1.42)
and dilute to 1 L with water. Allow solution to stand overnight before using.
27.15 Uranium Standard Solution (20 mg/L)—Dissolve 23.60 mg of U O (NIST SRM 950b or its replacement), or uranium
3 8
oxide of equal purity, in 1 mL of HNO (1 + 2) and dilute to 1 L with H SO (1 + 8).
3 2 4
28. Preparation of Ion Exchange Columns
28.1 Wash 250 g of the anion exchange resin alternately with three 350-mL portions of HCl (sp gr 1.19) and three 350-mL
portions of water. Allow the resin to remain in each solution for 30 min.
28.2 Fill each column to a height of 10 cm with ion exchange resin and rinse each column with 30 mL of HCl (sp gr 1.19).
NOTE 5—Immediately before each analysis, rinse each column with 30 mL of HCl (sp gr 1.19) and remove any entrapped air from the column.
29. Calibration and Standardization
29.1 Pipet ten 10-mL aliquots of plutonium matrix calibration solution (7 g/L) into separate 50-mL beakers and add 2 mL of
H SO (1 + 2).
2 4
29.2 Add 0.0, 1.0, 4.0, 7.0, and 10.0 mL of uranium standard solution (20 mg/L), respectively, to each of the 5 pairs of solutions
prepared in 29.1 and evaporate to dryness.
29.3 Add 4.0 mL of HCl (1 + 1) to each beaker and dissolve the residue.
29.4 Add 3 mL of hydroxylamine hydrochloride solution (NH OH·HCl, 100 g/L) to each beaker and warm the solution under
infrared lamps until the plutonium is reduced to Pu(III) as indicated by the blue color. If the solution is not blue, add more
NH OH·HCl solution and warm again.
NOTE 6—Plutonium is not adsorbed on the resin if it is in the reduced Pu(III) state.
29.5 Cool the solutions to room temperature and add 3 drops of SnCl ·2 H O solution (700 g/L) to each beaker.
2 2
NOTE 7—The stannous chloride prevents air oxidation of the Pu(III) during subsequent steps in the procedure.
29.6 Add 13 mL of HCl (sp gr 1.19) to each beaker.
29.7 Transfer each solution to a separate ion exchange column using five 1-mL portions of HCl (sp gr 1.19) to wash each beaker.
29.8 Wash the Pu(III) from each column with six 5-mL portions of HCl (sp gr 1.19).
29.9 Next, elute the uranium from each column by washing each column with six 5-mL portions of 0.1 N HCl. Collect the wash
solutions from each column in a 50-mL beaker and evaporate to dryness on a hot plate under infrared lamps.
29.10 Add 3 drops of HCl (sp gr 1.19) to dissolve each residue and wash the sides of the beaker with water.
29.11 Add 4 drops of NaCN solutions (50 g/L) and 2 drops of phenolphthalein solution to each beaker; then add NH OH
(1 + 13) until the indicator remains slightly pink.
29.12 Pipet 5 mL of triethanolamine buffer and 3.0 mL of Arsenazo I solution to each beaker.
29.13 Transfer each solution to a 25-mL volumetric flask and dilute to volume with water.
29.14 Allow the solutions to stand 1 h for maximum color development, and then measure the absorbance at 600 nm in 1-cm
cells versus a reference solution prepared from the reagents starting at 29.11.
29.15 Calibration Curve:
29.15.1 Process the results obtained in 29.14 in accordance with the procedure described in 31.1 and 31.2.
29.15.2 Each time samples are analyzed verify the calibration by processing duplicate aliquots of plutonium matrix calibration
solutions containing no uranium; also process a set of duplicates that contain 5 mL each of uranium standard (20 mg/L) added to
aliquots of plutonium matrix calibration solution by the procedure given in 29.3 through 29.14.
29.15.3 Process the results obtained in 29.15.2 in accordance with the procedure outlined in 31.3. If the individual calibration
value disagrees at the 0.05 significance level with the value of the constant obtained from the complete calibration set, investigate
and rectify the cause before proceeding with further analyses.
C759 − 18
30. Procedure
30.1 Prepare duplicate reagent blanks starting with 30.3.
30.2 Transfer a sample aliquot containing approximately 70 mg of plutonium weighed to 60.1 mg into a 50-mL beaker.
30.3 Add 5 mL of HCl (sp gr 1.19) to the beaker.
30.4 Evaporate the solution to near dryness slowly to avoid loss of sample.
NOTE 8—This eliminates excess nitrate which would prevent reduction of the plutonium.
30.5 Proceed with the analysis as described in 29.3 through 29.14.
30.6 Calculate the concentration of uranium in micrograms per gram of plutonium in accordance with instructions in Section
32.
31. Calculation of Calibration Factors
31.1 Calculate the corrected absorbance value for each standard solution as follows:
Y 5 r 2 s (3)
where:
Y = corrected absorbance value for standard,
r = absorbance value of standard obtained in 29.14, and
s = average absorbance value obtained in 29.14 for the duplicate calibration blanks with no uranium added.
31.2 Use the least squares formulas and the data from 31.1 to calculate values of A and B in the linear calibration equation:
Y 5 Ax1B, that best fits the data (4)
where:
A, B = constants (B should be approximately zero),
Y = corrected absorbance value from 31.1, and
x = micrograms of uranium in the standard calibration solution.
31.3 Calculate the individual calibration value for each standard solution processed simultaneously with each set of samples as
follows:
A'5 m/n (5)
where:
A' = individual calibration value for each standard solution,
n = micrograms of uranium in the standard solution, and
m = corrected absorbance of standard = p − q
where
p = absorbance for standard solution, and
q = average absorbance obtained from duplicate blank solutions.
31.4 Each individual value of A' should agree at the 0.05 significance level with the value of A obtained from the complete
calibration set.
32. Calibration of Uranium Concentration
32.1 Calculate the uranium concentration in the sample, R, micrograms per gram Pu, as follows:
R 5 ~Y 2 B!/AWC (6)
where:
R = micrograms U per gram plutonium,
A, B = constants in linear calibration equation,
C = grams Pu per gram plutonium nitrate solution in sample,
W = weight of sample aliquot, g, and
Y = a − b = corrected absorbance of sample solution
where:
a = absorbance of sample solution, and
b = average absorbance of duplicate calibration blanks.
C759 − 18
33. Precision and Bias
33.1 In the range from 300 to 1100 μg U/g Pu the standard deviation is 6100 μg/g; in the range from 1500 to 3000 μg U/g Pu
it is 650 μg/g.
THORIUM BY THORIN SPECTROPHOTOMETRIC TEST METHOD
34. Scope
34.1 This test method covers the determination of 10 to 150 μg of thorium per gram of plutonium in plutonium nitrate solutions.
34. Scope
34.1 This test method covers the determination of 10 to 150 μg of thorium per gram of plutonium in plutonium nitrate solutions.
35. Summary of Test Method
35.1 Lanthanum is added as a carrier and is precipitated along with thorium as insoluble fluoride, while the plutonium remains
in solution and is decanted after centrifugation of the sample. The thorium and lanthanum fluoride precipitate is dissolved in
perchloric acid, and the absorbance of the thorium-thorin complex is measured at a wavelength of 545 nm versus a reference
solution. The molar absorptivity of the colored complex is 15 600 for thorium concentration in the range from 5 to 70 μg Th/10
mL of the solution.
36. Interferences
36.1 Cations that form insoluble fluorides and colored complexes with thorin interfere in this test method.
37. Apparatus
37.1 Infrared Heat Lamps, 250-W, borosilicate glass.
37.2 Aluminum Heating Block—Drill a 150-mm high aluminum block to hold 16 12-mL centrifuge tubes and a thermometer.
In use the block is heated to 220°C.
37.3 Platinum Stirring Rod, 1 mm in diameter by 160 mm long.
37.4 Spectrophotometer, with matched cells having 10-mm light path.
37.5 Vacuum Transfer Device, approximately 150 mm long with a ⁄18 standard-taper ground-glass joint that fits a 10-mL
volumetric flask.
38. Reagents and Materials
38.1 Ammonium Peroxydisulfate ((NH ) S O ).
4 2 2 8
38.2 Hydrochloric Acid (sp gr 1.19)—Concentrated hydrochloric acid (HCl).
38.3 Hydrofluoric Acid (1 + 24)—Dilute 1 volume of concentrated hydrofluoric acid (HF, sp gr 1.15) with 24 volumes of water
and store in a polyethylene wash bottle.
38.4 Hydrogen Peroxide (30 %)—Concentrated hydrogen peroxide (H O ).
2 2
38.5 Hydroxylamine Hydrochloride Solution (250 g/L)—Dissolve 25 g of hydroxylamine hydrochloride (NH OH·HCl) in water
and dilute to 100 mL with water.
38.6 Lanthanum Nitrate Solution (10 g La/L)—Dissolve 3.12 g of lanthanum nitrate (La(NO ) ·6 H O) in water and dilute to
3 3 2
100 mL with water.
38.7 Nitric Acid (sp gr 1.42)—Concentrated nitric acid (HNO ).
38.8 Perchloric Acid (70 to 72 %)—Concentrated perchloric acid (HClO ).
38.9 Silver Nitrate Solution (2.5 g/L)—Dissolve 250 mg of silver nitrate (AgNO ) in water and dilute to 100 mL with water.
Store solution in an amber bottle.
38.10 Sulfuric Acid (1 + 35)—Add 1 volume of concentrated sulfuric acid (H SO , sp gr 1.84) to 35 volumes of water.
2 4
38.11 Thorin Solution (1 g/L)—Dissolve 1 g of thorin o-(2-hydroxy-3,6-disulfo-1-naphthylazo) benzenearsonic acid disodium
salt in water and dilute to 1 L.
38.12 Thorium Standard Solution (20.00 mg/L)—Dissolve 20.00 mg of high-purity thorium as the metal, oxide, or nitrate in HCl
(sp gr 1.19) and H O (30 %). Add 83 mL of HClO (70 to 72 %) and dilute to 1 L with water.
2 2 4
39. Calibration and Standardization
39.1 Reference Standards and Blanks:
C759 − 18
39.1.1 Pipet 1.00 mL of thorium standard (20 mg/L) into each of two 20-mL beakers, 2.00 mL into each of 2 more beakers and
3.00 mL into each of a third pair of beakers.
39.1.2 To two additional 20-mL beakers and to each of the solutions from 39.1.1, add 1 mL of HNO (sp gr 1.42) and 2 mL
of HClO (70 to 72 %).
39.1.3 Evaporate each solution to approximately 2 mL on a steam bath; then continue the evaporation to dryness under infrared
lamps on a hot plate.
39.1.4 Remove the beakers from the hot plate, and dissolve each residue in approximately 2 mL of H SO (1 + 35), dispensed
2 4
from a polyethylene wash bottle.
39.1.5 Transfer each solution to a 12-mL centrifuge tubing using three 2-mL rinses of H SO (1 + 35).
2 4
39.1.6 Add 5 drops of La(NO ) ·6 H O (10 g/L) solution and 0.1 mL of AgNO solution (2.5 g/L) and approximately 1 g of
3 3 2 3
(NH ) S O to each centrifuge tube.
4 2 2 8
39.1.7 Heat the tubes in a steam bath for 15 min.
39.1.8 Remove the tubes from the steam bath, cool, and add 1 mL of HF (sp gr 1.15). Stir the mixture with a platinum stirring
rod; rinse the rod with HF (1 + 24) after each stirring. After 5 min, centrifuge the tubes for 5 min.
39.1.9 Withdraw the supernatant plutonium-containing solution by means of vacuum and transfer to a plutonium residue bottle.
Invert the tubes onto a tissue for 1 to 2 min; then draw off to the residue bottle any liquid that has drained down the inner wall
of the tubes.
39.1.10 Wash the precipitate by adding 3 mL of HF (1 + 24) and mixing with the platinum rod. Rinse the platinum rod with
HF (1 + 24), wait 5 min, and centrifuge for 5 min. Repeat the procedure in 39.1.9 and proceed to step 39.1.11.
39.1.11 Add 1 mL of HClO (70 to 72 %) to each tube and place the tubes in the heated aluminum heating apparatus for 30
min.
39.1.12 Remove the tubes, cool, and add HClO (70 to 72 %) to adjust the volume in each tube to 0.5 mL.
39.1.13 Transfer each solution to a 10-mL volumetric flask using the vacuum transfer device with three 2-mL water rinses; then
add 0.5 mL of NH OH·HCl solution to each flask.
39.1.14 Prepare a reference solution by adding 0.5 mL of HClO (70 to 72 %), 0.5 mL of NH OH·HCl solution (250 g/L), and
4 2
6 mL of water to a 10-mL volumetric flask.
39.1.15 Place the flasks on a steam bath for 30 min.
39.1.16 Remove the flasks from the steam bath, cool, and add 1 mL of Thorin solution to each flask. Dilute to volume with
water, stopper, and shake.
39.1.17 Measure the absorbance of the solutions in 10-mm cells versus the reference solution at a wavelength of 545 nm.
39.1.18 Process the data obtained in 39.1.17 in accordance with the procedure described in 41.1.
39.2 Checking Calibration Curve:
39.2.1 Each time a set of samples is analyzed verify the procedure and calibration factor by processing two 2-mL thorium
standards and two blank solutions (with no thorium added) in accordance with the instructions in 39.1.2 through 39.1.17.
39.2.2 Process the data obtained in 39.2.1 in accordance with the procedures described in 39.2. If an individual calibration value
disagrees at the 0.05 significance level with the value of the constant obtained from the complete calibration set, investigate and
rectify the cause of the difficulty before proceeding with further analyses.
40. Procedure
40.1 Transfer a weighed aliquot of sample containing from 5 to 70 μg of thorium and no greater than 500 mg of plutonium into
a 20-mL beaker and proceed with the analysis as described in 39.1.2 through 39.1.17.
40.2 Calculate the thorium concentration in accordance with the procedure described in 41.3.
41. Calculation
41.1 Equation for Calibration Data:
41.1.1 Calculate the corrected absorbance value for each standard calibration solution as follows:
Y 5 r 2 s (7)
where:
Y = corrected absorbance value for the standard calibration solution,
r = absorbance value obtained in 39.1.17 for the standard calibration solution, and
s = average absorbance value obtained in 39.1.17 for the duplicate calibration blanks.
41.1.2 Use least squares formulas and the data from 41.1.1 to calculate values of A and B in the linear calibration equation:
Y 5 Ax1B, that best fits the data (8)
where:
A, B = constants (B should be approximately zero),
C759 − 18
Y = corrected absorbance from 41.1.1, and
x = micrograms thorium in the standard calibration solution.
41.2 Individual Calibration Values:
41.2.1 Calculate the individual calibration value for each standard solution processed with the samples as follows:
A'5 m/n (9)
where:
A' = individual calibration value for each standard solution,
n = micrograms of thorium in standard solution,
m = corrected absorbance value for standard solution p − q
where:
p = absorbance value from standard solution, and
q = average absorbance of duplicate blank solutions from 39.1.17.
41.2.2 Each individual A' should agree at the 0.05 significance level with the value of A obtained from the complete calibration
set.
41.3 Determine the thorium concentration of the sample as follows:
Th, µg/g Pu 5 R 5 Y 2 B /AWC (10)
~ !
where:
A andB = constants in the linear calibration equation,
W = sample mass, g,
C = grams Pu per gram of sample, and
Y = a − b = corrected absorbance of sample solution
where:
a = absorbance value for sample solution, and
b = average absorbance value from the duplicate reagent blanks described in 39.2.1.
42. Precision and Bias
42.1 The relative standard deviation is less than 2 % at thorium concentrations between 66 and 144 μg/g Pu, 4 % at a
concentration of 34 μg/g Pu, and 11 % at a concentration of 10 μg/g Pu.
42.2 The average value for thorium found in 91 measurements of 5 to 70 μg of thorium was 99 6 1 %.
IRON BY 1,10-PHENANTHROLINE SPECTROPHOTOMETRIC TEST METHOD
43. Scope
43.1 This test method covers the determination of microgram quantities of iron in plutonium nitrate solutions.
43. Scope
43.1 This test method covers the determination of microgram quantities of iron in plutonium nitrate solutions.
44. Summary of Test Method
44.1 Ferric ion is reduced to ferrous ion with hydroxylamine hydrochloride. Solutions of 1,10-phenanthroline and acetate buffer
+2
are added and the pH adjusted to 3.5 to 4.5. The absorbance of the red-orange complex [(C H N ) Fe] is read at 508 nm against
12 8 2 3
a sample blank containing all of the reagents except the 1,10-phenanthroline (6).
45. Interferences
45.1 Plutonium must be reduced to Pu(III) to avoid causing interference.
45.2 Silver and bismuth form precipitates.
45.3 Tolerance limits for 2 μg/mL Fe for elements that interfere in this determination are as follows (7):
Element μg/mL Element μg/mL
Cd 50 Mo 100
Hg(I) 10 Zr 10
Zn 10 Cr(VI) 25
W 5 V O 50
2 5
Ni 2 Mn(II) 200
Co 10 U O 400
3 8
C759 − 18
Cu 10 P O 20
2 5
Sn(II) 20 F 500
Pu(IV) 300 Np(IV) 100
46. Apparatus
46.1 Spectrophotometer, visible range with matched 10-mm cells.
47. Reagents and Materials
47.1 Acetate Buffer Solution—Dissolve 410 g of sodium acetate, (Na C H O ) in water, add 287 mL of glacial acetic acid, and
2 2 3 2
dilute to 1 L with water.
47.2 Ammonium Hydroxide (1 + 9)—Dilute 1 volume of NH OH (sp gr 0.9) with 9 volumes of water.
47.3 Hydrochloric Acid (1 + 9)—Dilute 1 volume of HCl (sp gr 1.19) with 9 volumes of water.
47.4 Hydroxylamine Hydrochloride Solution (104 g/L)—Dissolve 104 g of hydroxylamine hydrochloride (NH OH·HCl) in
water and dilute to 1 L with water.
47.5 Iron Standard (100 μg Fe/mL)—Carefully dissolve 100 mg of high-purity iron wire in 165 mL of HCl (1 + 1), cool, and
dilute to 1 L with water.
47.6 1,10-Phenanthroline Solution (0.2 weight/volume %)—Dissolve 2 g of 1,10-phenanthroline in water and dilute to 1 L with
water.
48. Procedure
48.1 Transfer an aliquot of sample that contains 5 to 75 μg of iron to a 30-mL beaker and add 10 mL acetate buffer solution
and 1 mL of hydroxylamine hydrochloride solution. Let solution stand for 10 min.
48.2 Add 1 mL of 1,10-phenanthroline solution and adjust the pH of the solution to the range from 3.5 to 4.5 with HCl (1 + 9)
or NH OH.
48.3 Transfer the solution to a 25-mL volumetric flask. Use water to wash the beaker and to dilute to volume. Stopper the flask
and mix thoroughly.
48.4 After 10 min, measure the absorbance of the sample aliquot against a sample blank that contains all of the reagents, except
1,10-phenanthroline, at a wavelength of 508 nm.
NOTE 9—For sample aliquots that contain iron in the range of 5 μg, cells of 5-cm length or longer should be used.
48.5 Prepare a calibration curve by adding to separate 30-mL beakers, containing 10 mL of acetate buffer solution and 1 mL
of hydroxylamine hydrochloride solution, the following amounts of iron standard: 0, 50, 100, 250, and 500 μL of iron standard
solution (100 μg Fe/mL). Follow the steps given in 48.2 through 48.4 of the procedure; then plot the absorbance versus the
micrograms of iron per 25 mL final volume of the solution.
49. Calculation
49.1 Calculate the iron in micrograms per gram of plutonium as follows:
Fe, µg/g Pu 5 C/PW (11)
where:
C = micrograms of Fe from calibration curve,
W = weight of sample, g, and
P = Pu, g/g of sample.
50. Precision and Bias
50.1 The relative standard deviation is 6 %.
IMPURITIES BY ICP-AES
(Cationic impurities may be determined using Test Method C1432 (Impurities by ICP-AES) with appropriate sample prepara-
tion and instrumentation.
CHLORIDE BY THIOCYANATE SPECTROPHOTOMETRIC TEST METHOD
51. Scope
51.1 This test method (8) is used to determine chloride in plutonium nitrate solution.
51. Scope
51.1 This test method (8) is used to determine chloride in plutonium nitrate solution.
C759 − 18
52. Summary of Test Method
52.1 After the sample aliquot is mixed with a solution containing ferrous ammonium sulfate, sulfamic acid, phosphoric acid,
and sulfuric acid, the chloride is steam distilled at a temperature of 140°C (Note 10). An aliquot of the distillate is mixed with ferric
ammonium sulfate and mercuric thiocyanate solutions. Thiocyanate ion is released in direct proportion to the chloride ion
concentration. The absorbance of the resulting red-brown ferric thiocyanate complex is read at 460 nm against a reagent blank.
NOTE 10—Save a portion of the distillate to use for the fluoride determination.
53. Interferences
53.1 Iodide, bromide, cyanide, and thiocyanate ions interfere. Nitrite interference is eliminated by use of sulfamic acid.
54. Apparatus
54.1 Steam Distillation Apparatus, including a steam generator and heating mantles.
54.2 Spectrophotometer and Matched 10-mm Cells.
55. Reagents and Materials
55.1 Chloride Standard Solution (5 μg Cl/mL)—Prepare a stock solution, A, Cl = 500 μg/mL,μg ⁄mL, by dissolving 824.4 mg
of dried NaCl in water and diluting to 1 L. Prepare chloride standard, 5 μg Cl/mL, by diluting 10 mL of stock solution A to 1 L
with water.
55.2 Ferric Ammonium Sulfate Solution (0.25 M)—Dissolve 12 g FeNH (SO ) ·12 H O in H SO (5 + 95) and dilute to 100
4 4 2 2 2 4
mL with H SO (5 + 95).
2 4
55.3 Ferrous Ammonium Sulfate (0.2 M) Sulfamic Acid (0.5 M) Solution—Dissolve 78.4 g of Fe(NH ) (SO ) ·6 H O and 48.6
4 2 4 2 2
g of NH SO H in H SO (5 + 95) and dilute to 1 L with H SO (5 + 95).
2 3 2 4 2 4
55.4 Mercuric Thiocyanate Solution (saturated)—Add Hg(SCN) to 90 % ethyl alcohol until the solution is saturated.
56. Procedure
56.1 Transfer 25 mL of acid mixture consisting of 0.2 M ferrous ammonium sulfate-0.5 M sulfamic acid solution, phosphoric
acid, and sulfuric acid mixed in the ratio 1 + 1 + 2.5, to a steam distillation flask and steam distill at 140°C until 100 mL of distillate
is collected. Retain this solution for use as a reagent blank.
56.2 Transfer an accurately weighed aliquot of plutonium nitrate solution that contains approximately 500 mg of plutonium to
a steam distillation flask and add 25 mL of acid mixture as described in 56.1. Steam distill at 140°C until 100 mL of distillate is
collected.
56.3 Transfer up to 6 mL of sample distillate, and 6 mL of reagent blank distillate, to separate 10-mL volumetric flasks. To each
flask, add 2 mL of 0.25 M ferric ammonium sulfate solution, 2 mL of saturated mercuric thiocyanate solution, and dilute to volume
with water solution and mix.
56.4 After 10 min, transfer the solutions to 1-cm cells and measure the absorbance of the sample versus the reagent blank at
a wavelength of 460 nm.
56.5 Prepa
...