ASTM D4698-92(1996)
(Practice)Standard Practice for Total Digestion of Sediment Samples for Chemical Analysis of Various Metals
Standard Practice for Total Digestion of Sediment Samples for Chemical Analysis of Various Metals
SCOPE
1.1 This practice covers two procedures for the total digestion of sediments for subsequent determination of metals by such techniques as flame atomic absorption spectrophotometry, graphite-furnace atomic absorption spectrophotometry, atomic emission spectroscopy, etc.
1.2 This practice is applicable in the subsequent determination of volatile, semivolatile, and nonvolatile metals of sediments.
1.3 Actual metal quantitation can be accomplished by following the various test methods outlined under other appropriate ASTM standards for the metal(s) of interest. Before selecting either of the digestion techniques outlined in this practice, the user should consult the appropriate quantitation standard(s) for any special analytical considerations, and Practice D3976 for any special preparatory considerations.
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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see Note 7.
1.5 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn. Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4698 – 92 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Total Digestion of Sediment Samples for Chemical Analysis
of Various Metals
This standard is issued under the fixed designation D 4698; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope tice, refer to Terminology D 1129.
3.2 Definitions of Terms Specific to This Standard:
1.1 This practice covers two procedures for the total diges-
tion of sediments for subsequent determination of metals by 3.2.1 total digestion—the dissolution of a sediment matrix
such techniques as flame atomic absorption spectrophotometry, such that quantitation will produce a measurement which is
graphite-furnace atomic absorption spectrophotometry, atomic more than 95% of the constituent present in the sample.
emission spectroscopy, etc.
3.2.2 partial digestion—the dissolution of a sediment ma-
1.2 This practice is applicable in the subsequent determina-
trix such that quantitation will produce a measurement of less
tion of volatile, semivolatile, and nonvolatile metals of sedi-
than 95% of the constituent present in the sample. In such
ments.
cases, recovery is operationally defined by the digestion
1.3 Actual metal quantitation can be accomplished by fol-
procedure.
lowing the various test methods outlined under other appropri-
ate ASTM standards for the metal(s) of interest. Before
4. Summary of Practices
selecting either of the digestion techniques outlined in this
4.1 Many procedures are available for the total digestion of
practice, the user should consult the appropriate quantitation
sediments prior to metal analysis, but almost all the methods
standard(s) for any special analytical considerations, and Prac-
fall into one of two main classes: fusion and subsequent
tice D 3976 for any special preparatory considerations.
dissolution of the bead, and wet digestion which directly
1.4 This standard does not purport to address all of the
dissolves the sample with mineral acids. Each of the classes
safety concerns, if any, associated with its use. It is the
has advantages and disadvantages, as do the individual proce-
responsibility of the user of this standard to establish appro-
dures which fall under them. The two procedures outlined in
priate safety and health practices and determine the applica-
this practice were selected because they are the least restricted,
bility of regulatory limitations prior to use. For a specific
in terms of utility, for dealing with a wide variety of matrices.
hazard statement, see Note 7.
Before choosing a particular method, the user should consult
1.5 The values stated in inch-pound units are to be regarded
the pertinent literature to determine the utility and applicability
as the standard. The values given in parentheses are for
of either method, prior to final selection; or if a less rigorous
information only.
4,5,6,7
digestion could be employed. Even then, experience with
a particular sample type or digestion test method, or both, may
2. Referenced Documents
have to be the final arbiter in test method selection.
2.1 ASTM Standards:
4.2 Field collected samples should be treated according to
D 1129 Terminology Relating to Water
the procedures outlined in Practice D 3976.
D 1192 Specification for Equipment for Sampling Water
4.3 Dried samples are ground to finer than 100 mesh (150
and Steam in Closed Conduits
μm) using an appropriate grinding device or system.
D 1193 Specification for Reagent Water
D 3976 Practice for Preparation of Sediment Samples for
4.4 Procedure A—Fusion with lithium metaborate/
Chemical Analysis tetraborate.
4.5 Procedure B—Wet digestion using a combination of
3. Terminology
hydrofluoric, perchloric, and nitric acids.
3.1 Definitions—For definitions of terms used in this prac-
Johnson, W., and Maxwell, J., Rock and Mineral Analysis, 2nd Edition, John
This practice is under the jurisdiction of ASTM Committee D-19 on Water and Wiley & Sons, New York, 1981, p. 489.
is the direct responsibility of Subcommittee D 19.07 on Sediments, Geomorphology, Pinta, M., Modern Methods for Trace Element Analysis, Ann Arbor Science
and Open-Channel Flow. Publishers, Ann Arbor, 1982, pp. 133–264.
Current edition approved Oct. 15, 1992. Published December 1992. Originally Dolezal, J., Povondra, C., and Sulcek, Z., Decomposition Techniques in
published as D 4698 – 87. Last previous edition D 4698 – 87. Inorganic Analysis, Elsevier Publishing Co., New York, 1968, pp. 11–157.
2 7
Annual Book of ASTM Standards, Vol 11.01. Shapiro, L., “Rapid Analysis of Silicate, Carbonate, and Phosphate Rocks,”
Annual Book of ASTM Standards, Vol 11.02. Revised Edition, U.S. Geological Survey Bulletin, 1401, 1975, p. 76.
D 4698
5. Significance and Use sufficiently high purity to permit its use without lessening the
accuracy of the subsequent quantitation.
5.1 The chemical analysis of sediments, collected from such
9.2 Purity of Water—Unless otherwise indicated, references
locations as streams, rivers, lakes, and oceans can provide
to water shall be understood to mean reagent water as defined
information of environmental significance.
by Type II of Specification D 1193.
5.2 These practices can be used with either suspended
9.3 Mixed Salt Standards—The mixed salt standards are
sediment (material actively transported by water) or bed
provided as a guide to the user for use with atomic absorption
sediment (material temporarily at rest on the bed of a water
analyses to reduce matrix and interelement interferences. They
body).
have been found effective for the constit-uents listed in 6.1.
5.3 Standardized practices for digesting sediments, for sub-
They may have to be modified to accommodate others.
sequent chemical analysis, will facilitate inter- and intra-areal
9.4 Cesium Chloride, Solution (4 g/L)—Dissolve4gof
comparisons as well as comparison of data generated by
CsCl in water and dilute to 1 L.
different groups. The use of total digestions also eliminates the
9.5 Diluent Solution—Dissolve6gofflux mixture in 500
ambiguities and interpretational difficulties associated with
mL of water. Add 12.5 mL concentrated nitric acid (sp gr 1.41),
partial digestions and the operational definitions that accom-
and dilute to 1 L with water.
pany them.
9.6 Flux Mixture—Thoroughly mix 1 part powdered anhy-
PROCEDURE A—FUSION drous lithium metaborate, LiBO , and 2 parts anhydrous
lithium tetraborate, Li B O . Store in a tightly closed bottle.
2 4 7
6. Scope
NOTE 1—It is possible to purchase pre-mixed fusion fluxes from several
6.1 This procedure is effective for the total digestion of
suppliers, and provided they are of sufficient purity, have been found quite
suspended and bottom sediments for the subsequent determi-
satisfactory.
nation of aluminum, calcium, iron, magnesium, potassium,
9.7 Mixed Metals Solution, Stock—Dissolve by appropriate
manganese, silicon, sodium, and titanium.
means, the following compounds, elements, or both: aluminum
6.2 This practice may be appropriate for the subsequent
metal (1.500 g), calcium carbonate (1.249 g), iron metal (1.000
determination of other metals provided the concentrations are
g), magnesium metal (0.200 g), manganese metal (0.040 g),
high enough or if the instrumental sensitivity is sufficient.
KCl (0.668 g), ammonium hexafluorosilicate (18.987 g), NaCl
(0.636 g), and ammonium titanyl oxalate (1.227 g), and dilute
7. Interferences
to 1000 mL with diluent solution (9.5). This solution will
7.1 Numerous inter-element interferences, both positive and
contain the following concentrations: aluminum (1500 mg/L),
negative, exist for this procedure and have been amply docu-
calcium (500 mg/L), iron (1000 mg/L), magnesium (200
,
4 5
mented elsewhere.
mg/L), manganese (40 mg/L), potassium (350 mg/L), silica
7.2 Interferences are eliminated or compensated for, or both,
(3000 mg/L), sodium (250 mg/L), and titanium (200 mg/L).
through the use of cesium chloride (CsCl), orthoboric acid
Store in a plastic or TFE-fluorocarbon bottle.
(H BO ), lithium metaborate (LiBO ), lithium tetraborate
3 3 2
9.8 Mixed Metals Solutions, Standards 1, 2, and 3—Take
(Li B O ), and the use of mixed salt standards during quanti-
2 4 7
respectively, a 10-, 6-, and 2-mL aliquot of the mixed metals
tation by flame atomic absorption spectrophotometry.
stock solution (9.7), and dilute to 100 mL in volumetric
glassware with standard diluent solution (9.5). Concentrations
8. Apparatus
are given in Table 1.
8.1 Graphite Crucibles, drill point, with a 7.5-mL capacity
9.9 Nitric Acid, concentrated (sp gr 1.41).
and a 1-in. (25.4 mm) outside diameter, ⁄4-in. (19.05 mm)
9.10 Nitric Acid (1 + 1)—Add 250 mL of concentrated
inside diameter, and total depth of 1 ⁄8 in. (34.925 mm).
nitric acid (sp gr 1.41) to 250 mL water. Store in a plastic
8.2 Magnetic Stirrer.
bottle.
8.3 Muffle Furnace, capable of reaching a temperature of at
9.11 Orthoboric Acid Solution (50 g/L)—Dissolve 50 g of
least 1000°C.
H BO in water and dilute to 1 L. Heat may be required to
3 3
complete dissolution. Prepare fresh daily because orthoboric
9. Reagents
acid may precipitate within 12 to 18 h.
9.1 Purity of Reagents—Reagent grade chemicals shall be
TABLE 1 Concentrations of Mixed Metals
used in all digestions. Unless otherwise indicated, it is intended
Solutions 1, 2, and 3
that all reagents conform to the specifications of the Committee
Standard 1, Standard 2, Standard 3,
on Analytical Reagents of the American Chemical Society
mg/L mg/L mg/L
where such specifications are available. Other grades may be
Volume (mL) 10 6 2
used, provided it is first ascertained that the reagent is of
Iron 100 60 20
Magnesium 20 12 4
Silicon 300 180 60
Aluminum 150 90 30
Reagent Chemicals, American Chemical Society Specifications, American
Titanium 20 12 4
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Calcium 50 30 10
listed by the American Chemical Society, see Analar Standards for Laboratory
Sodium 25 15 5
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Potassium 35 21 7
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Manganese 4 2 1
MD.
D 4698
10. Procedure H BO solution (Note 5).
3 3
10.15 See the appropriate ASTM test methods for subse-
10.1 Immediately before each use, clean all glassware by
quent quantitation.
rinsing first with HNO (1 + 1), and then with water.
10.2 Dry the sediment sample by an appropriate procedure
PROCEDURE B—WET DIGESTION
such as freeze-drying, or oven drying at 105°C (see Practice
11. Scope
D 3976).
10.3 If the sediment sample is greater than 100 g, split it to 11.1 This procedure is effective for the total digestion of
less than 100 g by the use of a nonmetallic sample splitter
suspended and bottom sediments for the subsequent determi-
(riffle sampler) or by coning and quartering. nation of aluminum, calcium, iron, magnesium, manganese,
10.4 Grind the sample with an appropriate system until all
potassium, sodium, titanium, strontium, lithium, copper, zinc,
material is finer than 100 mesh (150 μm). cadmium, lead, cobalt, nickel, chromium, arsenic, antimony,
10.5 Transfer approximately 1.2 g of flux mixture to a
and selenium.
waxed or plastic-coated weighing paper (6 in. by 6 in. (152.4 11.2 This practice may be appropriate for the subsequent
mm by 152.4 mm)). Weigh and transfer 0.2000 g of finely determination of other metals provided the concentrations are
ground sample to the flux mixture and mix by rolling succes- high enough or if the instrumental sensitivity is sufficient.
sive corners of the paper about 30 times. Carefully transfer the
12. Interferences
combined sample/flux to a graphite crucible, and tamp down
12.1 Numerous inter-element interferences, both positive
by gently tapping the crucible on a tabletop.
and negative, exist for this procedure and have been docu-
10.6 Weigh appropriate sediment or rock standards and treat
, ,
4 5 9
mented elsewhere.
as in 10.5.
12.2 Interferences are eliminated, compensated for, or both,
10.7 Carry several blanks through the procedure by using
through the use of cesium chloride (CsCl), the use of mixed
only flux and treat as in 10.5.
salt standards, and background correction if quantitation is by
10.8 Fuse the mixtures in a muffle furnace, preheated to
atomic absorption spectroscopy.
1000°C, for 30 min.
13. Apparatus
NOTE 2—When the crucibles, samples, and crucible racks are placed in
the muffle furnace, the temperature may drop as much as 200°C. Time is
13.1 TFE-Fluorocarbon Beakers, 100-mL capacity, thick
still measured from the time of insertion in the furnace.
wall, capable of withstanding temperature up to 260°C.
10.9 Remove the crucibles from the furnace and allow to
13.2 Hot Plate, electric or gas, capable of reaching at least
cool; dislodge the beads by gentle tapping or with a spatula.
250°C.
13.3 Perchloric Acid Hood, with appropriate washdown
NOTE 3—The beads can be dissolved immediately after cooling, or can
facility and gas or electric outlets.
be stored in plastic vials for dissolution at a later time.
10.10 Place the bead in an acid-washed 250-mL plastic
14. Reagents
bottle and add a ⁄4 to 1 in. (19.05 to 25.4 mm) magnetic stirring
14.1 Purity of Reagents—See 9.1.
bar. Add approximately 50-mL boiling water using a plastic
14.2 Purity of Water—See 9.2.
graduate, place the bottle on a magnetic stirrer, and mix. Add
14.3 The mixed salt standards are provided as a guide to the
5mLofHNO (1 + 1) to each bottle and stir rapidly for about
user for use with atomic absorption analyses to reduce matrix
60 min. Cap the bottle lightly to prevent both contamination
and interelement interferences. They have been found effective
and possible spattering.
for the constituents listed in 11.1. They may have to be
10.11 Immediately after 60 min, remove the bottles from the
modified to accommodate others.
stirrers, and add about 100 mL of water to prevent the
14.4 Standard Solution, Aluminum [1.00 mL 5 1.00 mg
polymerization of silica.
Al]—Dissolve 1.000 g of aluminum metal in 20 mL of HCl (sp
gr 1.19) with a trace of a mercury salt to catalyze the reaction,
NOTE 4—The solutions may contain small amounts of graphite from the
crucibles which can be ignored. However, if the solution is cloudy, this and dilute to 1000 mL with water.
indicates a very high concentration of silica i
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.