ASTM D1971-16(2021)e1
(Practice)Standard Practices for Digestion of Water Samples for Determination of Metals by Flame Atomic Absorption, Graphite Furnace Atomic Absorption, Plasma Emission Spectroscopy, or Plasma Mass Spectrometry
Standard Practices for Digestion of Water Samples for Determination of Metals by Flame Atomic Absorption, Graphite Furnace Atomic Absorption, Plasma Emission Spectroscopy, or Plasma Mass Spectrometry
SIGNIFICANCE AND USE
4.1 The determination of metals in water often requires the measurement of total (suspended and dissolved) metals as well as soluble (dissolved) metals. In such cases, consistent and dependable digestion procedures must be used so that data derived for the total metals content is reliable.
4.2 The practices given are applicable to a wide variety of sample types for the purpose of preparing a sample for metals analyses by atomic absorption spectrophotometry or plasma emission spectroscopy (see Test Method D1976, Practice D3919, Practice D4691, and Test Method D4190) or plasma-mass spectrometry (see Test Method D5673) and have been shown to give good recovery in the following matrices: industrial effluents; waste water treatment plant influents, sludges, dewatered sludges, and effluents; river and lake waters; and plant and animal tissues. Elements which have shown good recovery include: copper, nickel, lead, zinc, cadmium, iron, manganese, magnesium, and calcium.
4.2.1 Good recovery for the indicated sample types and metals may not be achieved at all times due to each sample's unique characteristics. Users must always validate the practice for their particular samples.
4.3 The analytical results achieved after applying these practices cannot necessarily be deemed as a measure of bioavailable or environmentally available elements.
4.4 These three practices may not give the same recovery when applied to the same sample, nor will they necessarily give the same results as achieved using other digestion techniques. An alternate digestion technique is Practice D4309.
SCOPE
1.1 Most atomic absorption and plasma emission spectroscopy, and plasma-mass spectrometric test methods require that the metals of interest be dissolved in a liquid phase before being introduced into the spectrophotometer. These practices describe digestion or dissolution procedures whereby analyte metals associated with the solid fraction of a sample can be brought into solution for subsequent analysis. The following practices are included:
Sections
Practice A—Digestion with Mineral Acids and
Elevated Pressure
8 through 13
Practice B—Digestion with Mineral Acids and
Heating at Atmospheric Pressure
14 through 19
Practice C—In-Bottle Digestion with Mineral Acids
20 through 25
1.2 These practices have been demonstrated to be applicable to a wide variety of sample types and sample matrices, and in many cases, will give complete dissolution of the analyte metals of interest. They are by no means the only digestion procedures available.
1.3 The user of these practices should be cautioned that these practices may not completely dissolve all portions of a sample's solid phase and may not give complete recovery of the desired analyte metals. In these cases, other digestion techniques are available that will effect complete dissolution of a sample. It is the user's responsibility to ensure the validity of these practices for use on their particular sample matrix, for their metals of interest.
1.4 This practice assumes that the criteria established in Guide D3856 can be met.
1.5 These digestion procedures have been selected for their wide application, low cost, and ease of use.
1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematical conversion to inch-pound units that are provided for information only and are not considered standard.
1.7 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. Specific hazard statements are given in Section 6.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization establi...
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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.
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Designation: D1971 − 16 (Reapproved 2021)
Standard Practices for
Digestion of Water Samples for Determination of Metals by
Flame Atomic Absorption, Graphite Furnace Atomic
Absorption, Plasma Emission Spectroscopy, or Plasma
Mass Spectrometry
This standard is issued under the fixed designation D1971; 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.
ε NOTE—The WTO caveat was editorially added in November 2021.
1. Scope 1.6 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are mathematical
1.1 Most atomic absorption and plasma emission
conversion to inch-pound units that are provided for informa-
spectroscopy, and plasma-mass spectrometric test methods
tion only and are not considered standard.
require that the metals of interest be dissolved in a liquid phase
1.7 This standard does not purport to address all of the
before being introduced into the spectrophotometer. These
safety concerns, if any, associated with its use. It is the
practices describe digestion or dissolution procedures whereby
responsibility of the user of this standard to establish appro-
analyte metals associated with the solid fraction of a sample
priate safety, health, and environmental practices and deter-
can be brought into solution for subsequent analysis. The
mine the applicability of regulatory limitations prior to use.
following practices are included:
Specific hazard statements are given in Section 6.
Sections
PracticeA—Digestion with MineralAcids and 8 through 13 1.8 This international standard was developed in accor-
Elevated Pressure
dance with internationally recognized principles on standard-
Practice B—Digestion with MineralAcids and 14 through 19
ization established in the Decision on Principles for the
Heating atAtmospheric Pressure
Practice C—In-Bottle Digestion with MineralAcids 20 through 25 Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.2 Thesepracticeshavebeendemonstratedtobeapplicable
Barriers to Trade (TBT) Committee.
to a wide variety of sample types and sample matrices, and in
many cases, will give complete dissolution of the analyte
2. Referenced Documents
metals of interest. They are by no means the only digestion
procedures available. 2.1 ASTM Standards:
D511 Test Methods for Calcium and Magnesium In Water
1.3 The user of these practices should be cautioned that
D857 Test Method for Aluminum in Water
these practices may not completely dissolve all portions of a
D858 Test Methods for Manganese in Water
sample’s solid phase and may not give complete recovery of
D1068 Test Methods for Iron in Water
the desired analyte metals. In these cases, other digestion
D1129 Terminology Relating to Water
techniques are available that will effect complete dissolution of
D1193 Specification for Reagent Water
a sample. It is the user’s responsibility to ensure the validity of
D1687 Test Methods for Chromium in Water
these practices for use on their particular sample matrix, for
D1688 Test Methods for Copper in Water
their metals of interest.
D1691 Test Methods for Zinc in Water
1.4 This practice assumes that the criteria established in
D1886 Test Methods for Nickel in Water
Guide D3856 can be met.
D1976 Test Method for Elements in Water by Inductively-
Coupled Plasma Atomic Emission Spectroscopy
1.5 These digestion procedures have been selected for their
D2972 Test Methods for Arsenic in Water
wide application, low cost, and ease of use.
D3082 Test Method for Boron in Water
These practices are under the jurisdiction of ASTM Committee D19 on Water
and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituents
in Water. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2021. Published December 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1991. Last previous edition approved in 2016 as D1971 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D1971-16R21E01. the ASTM website.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
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D1971 − 16 (2021)
D3370 Practices for Sampling Water from Flowing Process ing in a metal analyte measurable by atomic absorption
Streams spectrophotometry, plasma emission spectroscopy or plasma
D3372 Test Method for Molybdenum in Water mass spectrometry after applying the digestion procedure in
D3373 Test Method for Vanadium in Water either Practice A, Practice B, or Practice C.
D3557 Test Methods for Cadmium in Water 3.2.2.1 Discussion—The choice of PracticeA, B, or C shall
D3558 Test Methods for Cobalt in Water be noted in reporting resultant data.
D3559 Test Methods for Lead in Water
4. Significance and Use
D3645 Test Methods for Beryllium in Water
D3697 Test Method for Antimony in Water
4.1 The determination of metals in water often requires the
D3859 Test Methods for Selenium in Water measurement of total (suspended and dissolved) metals as well
D3856 Guide for Management Systems in Laboratories
as soluble (dissolved) metals. In such cases, consistent and
Engaged in Analysis of Water dependable digestion procedures must be used so that data
D3866 Test Methods for Silver in Water
derived for the total metals content is reliable.
D3919 Practice for Measuring Trace Elements in Water by
4.2 The practices given are applicable to a wide variety of
Graphite Furnace Atomic Absorption Spectrophotometry
sample types for the purpose of preparing a sample for metals
D3920 Test Method for Strontium in Water
analyses by atomic absorption spectrophotometry or plasma
D4190 TestMethodforElementsinWaterbyDirect-Current
emission spectroscopy (see Test Method D1976, Practice
Plasma Atomic Emission Spectroscopy
D3919, Practice D4691, and Test Method D4190) or plasma-
D4191 Test Method for Sodium inWater byAtomicAbsorp-
mass spectrometry (see Test Method D5673) and have been
tion Spectrophotometry
shown to give good recovery in the following matrices:
D4192 Test Method for Potassium in Water by Atomic
industrial effluents; waste water treatment plant influents,
Absorption Spectrophotometry
sludges, dewatered sludges, and effluents; river and lake
D4309 Practice for Sample Digestion Using Closed Vessel
waters; and plant and animal tissues. Elements which have
Microwave Heating Technique for the Determination of
shown good recovery include: copper, nickel, lead, zinc,
Total Metals in Water
cadmium, iron, manganese, magnesium, and calcium.
D4382 TestMethodforBariuminWater,AtomicAbsorption
4.2.1 Good recovery for the indicated sample types and
Spectrophotometry, Graphite Furnace
metals may not be achieved at all times due to each sample’s
D4691 Practice for Measuring Elements in Water by Flame
unique characteristics. Users must always validate the practice
Atomic Absorption Spectrophotometry
for their particular samples.
D5673 Test Method for Elements in Water by Inductively
4.3 The analytical results achieved after applying these
Coupled Plasma—Mass Spectrometry
practices cannot necessarily be deemed as a measure of
2.2 EPA Method:
bioavailable or environmentally available elements.
EPA-600/4-79-020 Methods for Chemical Analysis of Wa-
ter and Wastes, Revised March 1983
4.4 These three practices may not give the same recovery
EPA-600/R-94/111 Methods for the Determination of Met-
when applied to the same sample, nor will they necessarily
als in Environmental Samples—Supplement 1
give the same results as achieved using other digestion
2.3 USGS Method:
techniques.AnalternatedigestiontechniqueisPracticeD4309.
USGS Open File Report 96–225 Methods ofAnalysis by the
5. Reagents
U.S. Geological Survey National Water Quality
Laboratory—In-Bottle Acid Digestion of Whole Water
5.1 Purity of Reagents—Reagent grade chemicals shall be
Samples
used throughout. Acids shall have a low-metal content or
should be doubly distilled and checked for purity. Unless
3. Terminology
otherwise indicated, it is intended that all reagents shall
3.1 Definitions:
conform to the Specifications of the Committee on Analytical
3.1.1 For definitions of terms used in this standard, refer to
Reagents of the American Chemical Society. Other grades
Terminology D1129.
may be used, provided it is first ascertained that the reagent is
3.2 Definitions of Terms Specific to This Standard:
of sufficiently high purity to permit its use without lessening
3.2.1 digestion, n—treating a sample with the use of heat or
the accuracy of the determination.
elevated pressures, or both, usually in the presence of chemical
5.2 Purity of Water—Unless otherwise indicated, references
additives, to bring analytes of interest into solution or to
towatershallbeunderstoodtomeanreagentwaterconforming
remove interfering matrix components, or both.
to Specification D1193, Type I. Other reagent water types may
3.2.2 total recoverable, n—a descriptive term relating to the
be used, provided it is first ascertained that the water is of
metal forms recovered in the acid-digestion procedures result-
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
AvailablefromUnitedStatesEnvironmentalProtectionAgency(EPA),William Standard-Grade Reference Materials, American Chemical Society, Washington,
Jefferson Clinton Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
http://www.epa.gov. Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
Available from U.S. Geological Survey (USGS) National Center, 12201 U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
Sunrise Valley Dr., Reston, VA 20192, https://www.usgs.gov. copeial Convention, Inc. (USPC), Rockville, MD.
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D1971 − 16 (2021)
sufficiently high purity to permit its use without lessening the automaticcyclingisdesirable.Asthedigestingsamplesrelease
bias and precision of the determination. acidic fumes, the portions of the autoclave coming in contact
with these fumes should be constructed of acid resistant
6. Hazards
materials.
6.1 These practices involve the heating of solutions of
NOTE 1—Prolonged use of an autoclave with a stainless steel interior
mineralacids.Appropriateprecautionsshallbetakentoprotect
for this practice may result in discoloration of the autoclave walls. This
the analyst from these acids and heated containers. Heated discoloration has not been shown to cause any problems with autoclave
operation. A commercially available autoclave with a stainless steel
samples and acids may splatter or boil unexpectedly.
interior has been in daily use for this practice, as well as for routine
sterilization purposes, for ten years without any degradation of the
7. Sampling
autoclave or its performance.
7.1 As with all chemical assay procedures, the user of this
practiceshallensurethatallsamplealiquotusedareadequately
11. Interferences
representative of the environmental situation being monitored.
11.1 The interferences of this practice relate to the inability
7.2 Appropriate sampling and subsampling techniques for
of the described procedure to quantitatively dissolve the
particular environmental samples can be found in other refer-
analyte metals of interest in certain situations. These interfer-
ences.
ences can be either physical or chemical.
7.3 Collect the sample in accordance with Practices D3370.
11.2 Physical Interferences—Insomesamples,themetalsof
interest are bound or occluded in a matrix that is impervious to
PRACTICE A—DIGESTION WITH
dissolutionbytheacids.Thisismostfrequentlyencounteredin
MINERAL ACIDS AND
geological and boiler water samples.
ELEVATED PRESSURE
11.3 Chemical Interferences—Thecompletedissolutionofa
8. Scope
metal of interest may not occur due to the digestion conditions
being insufficiently rigorous for that particular metal. In other
8.1 This practice presents a digestion technique that has
instances, the chemical makeup of the sample may render the
broad application and can be performed inexpensively with
digestion acids ineffective.
minimal labor, equipment, and space. In addition, this practice
allows for many samples to be processed quickly and simul-
12. Reagents and Materials
taneously under the same conditions.
12.1 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
9. Summary of Practice
chloric acid (HCl).
9.1 Samples are placed in loosely capped, heat-, and aci-
12.2 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
dresistant containers with selected reagents and subjected to
(HNO ).
121°C and 103 kPa (15 psi) for 30 min. After removing any
12.3 Filter Paper—Purchase suitable filter paper. Typically
particulate matter remaining, the digestate is ready for analysis
the filter papers have a pore size of 0.45-µm membrane.
by atomic absorption spectrophotometry, plasma emission
Material such as fine-textured, acid-washed, ashless paper, or
spectroscopy, or plasma-mass spectrometry.
glass fiber paper are acceptable. The user must first ascertain
9.2 The practice may be found to be more applicable to a
that the filter paper is of sufficient purity to use without
particular sample or analytical scheme after appropriate modi-
adversely affecting the bias and precision of the test method
fications of reagent addition, temperature, pressure, digestion
time, or container selection. Any such modifications to this
13. Procedures
practice must be validated by the user.
13.1 In this section two types of digestion procedures are
10. Apparatus
described: one for liquid samples (see 13.2) and one for solid
and semi-solid samples (see 13.3).
10.1 Digestion Containers—50 mL disposable polypropyl-
ene centrifuge tubes and 125 mLpolypropylene reagent bottles
13.2 Liquid Samples:
with screw caps have been used successfully. Any container
13.2.1 Using a sample volume from 40 to 100 mL, pipet an
that is not attacked by the digestion conditions, is sufficiently
aliquot of sample, hydrochloric acid, and nitric acid into a
free of the analyte(s) of interest, and can be loosely capped,
digestion container in the following ratio: 100 volumes sample
may be used.
to 5 volumes HCl (sp gr 1.19) to 1 volume HNO (sp gr 1.42).
13.2.2 Swirl digestion con
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