ASTM D5174-23

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: D5174 − 23
Standard Test Method for
Trace Uranium in Water by Pulsed-Laser Phosphorimetry
This standard is issued under the fixed designation D5174; 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 D5847 Practice for Writing Quality Control Specifications
for Standard Test Methods for Water Analysis
1.1 This test method covers the determination of total
D6001 Guide for Direct-Push Groundwater Sampling for
uranium, by mass concentration, in water within the calibrated
Environmental Site Characterization
range of the instrument, 0.1 μg ⁄L or greater. Samples with
E131 Terminology Relating to Molecular Spectroscopy
uranium mass concentrations above the laser phosphorimeter
dynamic range are diluted to bring the concentration to a
3. Terminology
measurable level.
3.1 Definitions:
1.2 This test method was used successfully with reagent
3.1.1 For definitions of terms used in this test method, refer
water. It is the user’s responsibility to ensure the validity of this
to Terminologies D1129 and E131.
test method for waters of untested matrices.
3.1.2 For terms not defined in this test method or in
1.3 The values stated in SI units are to be regarded as the
Terminology D1129 or E131, reference may be made to other
standard.
published glossaries.
1.4 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
4.1 This test method is based on the utilization of a laser
responsibility of the user of this standard to establish appro-
phosphorimeter to determine total uranium, by mass, in water
priate safety, health, and environmental practices and deter-
samples.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
4.2 A sample aliquant is pipetted into a pretreated glass vial.
dance with internationally recognized principles on standard-
Concentrated HNO and hydrogen peroxide are added and the
ization established in the Decision on Principles for the
sample heated to dryness. This step is repeated as necessary
Development of International Standards, Guides and Recom-
and the residue is dissolved in dilute HNO . A complexant is
mendations issued by the World Trade Organization Technical
added to an aliquant of this sample and analyzed in the
Barriers to Trade (TBT) Committee.
phosphorimeter.
4.3 For screening purposes only, an aliquant of the sample
2. Referenced Documents
may be pipetted directly into the phosphorimeter cell contain-
2.1 ASTM Standards:
ing uranium complexant and read. This cannot be done if the
D1129 Terminology Relating to Water
sample was preserved with HCl or if the matrix is not known.
D1193 Specification for Reagent Water
D2777 Practice for Determination of Precision and Bias of
5. Significance and Use
Applicable Test Methods of Committee D19 on Water
5.1 This test method is useful for the analysis of total
D3370 Practices for Sampling Water from Flowing Process
uranium in water following wet-ashing, as required, due to
Streams
impurities or suspended materials in the water.
D4448 Guide for Sampling Ground-Water Monitoring Wells
6. Interferences
6.1 Absorption (Inner Filter Effect)—This effect is more
This test method is under the jurisdiction of ASTM Committee D19 on Water
and is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-
severe with ultraviolet excitation light (337 nm) than with
cal Analysis.
visible excitation because many prevalent compounds have
Current edition approved June 1, 2023. Published July 2023. Originally approved
pi-bonding and absorb strongly in this region. Ferric iron and
in 1991. Last previous edition approved in 2013 as D5174 – 07 (2013) which was
withdrawn January 2022 and reinstated in June 2023. DOI: 10.1520/D5174-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM See American National Standard Glossary of Terms in Nuclear Science and
Standards volume information, refer to the standard’s Document Summary page on Technology (ANSI N1.1), available from American National Standards Institute,
the ASTM website. 1430 Broadway, New York, NY 10014, www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5174 − 23
oxy-anions such as nitrate and organic acids are examples. with deionized water before using. This is necessary to reduce
Visible excitation (425 nm) may be absorbed by yellow sample contamination from leachable uranium.
solutions, for example, chromate. The consequences of this
may be reduced signals and low analysis results. 8. Reagents
6.2 Lumiphors—Many organic substances, such as humic 8.1 Purity of Reagents—Reagent grade chemicals shall be
acids and organic degradation products from incomplete ashing used in all tests. Unless otherwise indicated, it is intended that
emit luminescence of varying lifetimes after excitation. An all reagents shall conform to the specifications of the Commit-
advantage of kinetic phosphorescence measurement is the tee on Analytical Reagents of the American Chemical Society.
ability to determine if interferences are present by observing Other grades may be used, provided it is first ascertained that
the lifetime of the decay. the reagent is of sufficiently high purity to permit its use
without lessening the accuracy of the determination. Reagent
6.3 Quenching—Shortened triplet-state lifetime and reduced
blanks shall be run with all determinations.
phosphorescence intensities of the excited uranyl complex
result when quenching occurs. Reliable results cannot be 8.2 Purity of Water—Unless otherwise indicated, references
obtained when quenching exceeds 80 % to 90 %. Reducing to water shall be understood to mean reagent water conforming
agents such as alcohols, halides except fluoride, and metals to Specification D1193, Type I or better.
with electronic energy levels overlapping those of uranyl ion
8.3 Hydrogen Peroxide—Standard 30 % solution of hydro-
are strong quenching agents; examples are silver, lead, iron
gen peroxide (H O ); commercially available reagent grade.
2 2
(II), manganese (II), and thallium. Results from single time-
8.4 Nitric Acid—(sp gr 1.42) concentrated nitric acid
gated instruments are particularly sensitive to even mild
(HNO ).
quenching agents such as aluminum (III), magnesium (II),
calcium (II), and strontium (II). 8.5 Nitric Acid 4 M—Add 250 mL of concentrated nitric
acid (HNO ) to 500 mL of reagent water and dilute to 1 L in
6.4 Competing Reactions—For this test method to perform
reagent water, Type I or better.
well, the uranyl ion must be protected from various intermo-
lecular mechanisms which rapidly quench the uranyl lumines-
8.6 Nitric Acid 0.8 M—Add 50 mL of concentrated nitric
cence. Complexation fulfills this need and examples of effec- acid (HNO ) to 500 mL of reagent water and dilute to 1 L in
tive agents are phosphoric acid, polyphosphates, and Uraplex.
reagent water, Type I or better.
6.5 Hydrochloric acid, if present, is an interference unless
NOTE 1—Reagent blank shall be run on the nitric acid to analyze for the
eliminated during digestion. level of uranium.
8.7 Uranium Complexant—Phosphoric acid or Uraplex are
6.6 If the concentration of uranium in the samples exceeds
some complexants that may be used.
the calibrated range of the instrument, samples are diluted
1/100 (or otherwise as appropriate) in 0.8 M nitric acid.
9. Calibration and Standardization
6.7 When concentrations of interferences in the samples
9.1 Preparation of Standards and Sample for Laser
prevent obtaining an acceptable measurement, samples are
Measurement—Standards and samples shall be prepared in a
diluted in 0.8 M nitric acid to minimize the effects of the
similar matrix for phosphorimetric measurement. The final
interferences.
sample preparation step puts uranium into a 0.8 M HNO
7. Apparatus
matrix. Use uranium standards traceable to the SI through a
national metrology institute such as NIST or NPL.
7.1 Laser Phosphorimeter, meeting the following criteria:
7.1.1 Detection Limit—The MDL for uranium is generally
9.2 Calibration of Phosphorimeter—The instructions for the
0.1 μg/L or less.
operation of the laser phosphorimeter are provided by the
7.1.2 Dynamic Range—The phosphorimeter must handle an
manufacturer. The phosphorimeter should be calibrated each
analytical range of 400 or greater.
day of use and the calibration verified with standards obtained
7.1.3 Instrumental Precision—The precision of repetitive
from a different stock solution than used to prepare the
measurements sufficient to obtain a relative standard deviation
calibration standards.
of less than 15 % at the low points of the calibration curves.
10. Sampling
7.2 Labware—If samples containing less than 0.1 μg ⁄L
uranium are to be analyzed, digestion vessels (both TFE-
10.1 Collect the sample in accordance with the applicable
fluorocarbon and glassware) if used, and liquid scintillation
methods as described in Practices D3370, D4448, and Guide
vials should be leached in 4 M nitric acid and rinsed thoroughly
D6001 or other approved practices or guides.
The sole source of supply of the apparatus known to the committee at this time
is Chemchek Instruments, Inc., 1845 Terminal Drive, Suite #101, Richland, WA, ACS Reagent Chemicals, Specifications and Procedures for Reagents and
99354-4959. Consult appropriate equipment manuals for explanations of calibration Standard-Grade Reference Materials, American Chemical Society, Washington,
and calculations. If you are aware of alternative suppliers, please provide this DC. For suggestions on the testing of reagents not listed by the American Chemical
information to ASTM International Headquarters. Your comments will receive Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
careful consideration at a meeting of the responsible technical committee, which U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
you may attend. copeial Convention, Inc. (USPC), Rockville, MD.
D5174 − 23
11. Procedure where:
MDL = the method detection limit at the 99 % confidence
0.99
11.1 Pipet 5.0 mL of sample into a glass vial previously
level,
treated as described in 7.2.
S = standard deviation of the measured mass concen-
B
11.2 Add 1 mL of concentrated HNO and two or three trations of uranium in replicate blanks (μg/L),
th
drops of 30 % hydrogen peroxide. t = 99 percentile of Student’s t-distribution with
Stud
n – 1 degrees of freedom (default = 3.143 for 6
11.3 Place the vial on a hot plate and heat to dryness. Take
degrees of freedom),
care that spattering of the sample does not occur.
n = number of blanks analyzed in the study (default =
7),
NOTE 2—Placing the vial in a 50 mL beaker makes it easier to handle
x = measured mass concentrations of uranium in the
and not so apt to be knocked over.
i
th
i blank, and
11.4 Remove the vials from the hot plate and add 1 mL of
x¯ = mean of the measured mass concentrations of
concentrated HNO , two or three drops of 30 % hydrogen
uranium in all replicate blanks (μg/L).
peroxide, and heat to dryness. Repeat as necessary until only a
12.4 Method Reporting Limit (RL):
white or translucent residue remains.
12.4.1 The method reporting limit (RL) is defined as the
11.5 Add 1.0 mL of 4 M HNO and warm gently, if
3 lowest non-z
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