ASTM D3372-92(1996)
(Test Method)Standard Test Method for Molybdenum in Water
Standard Test Method for Molybdenum in Water
SCOPE
1.1 This test method covers the determination of dissolved and total recoverable molybdenum in most waters, wastewaters, and brines by atomic absorption spectroscopy.
1.2 This test method is applicable in the range from 1 to 25 μg/L of molybdenum. The range may be extended by dilution of the sample.
1.3 This test method has been used successfully with natural and reagent waters. It is the user's responsibility to ensure the validity of this test method for waters of untested matrices.
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 specific precautionary statements, see Note 3 and Note 9.
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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NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn.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 3372 – 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 Test Method for
Molybdenum in Water
This standard is issued under the fixed designation D 3372; 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.
This standard has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and
Standards for the specific year of issue which has been adopted by the Department of Defense.
1. Scope cal term relating to the forms of molybdenum that are
determinable by the digestion procedure described in this test
1.1 This test method covers the determination of dissolved
method.
and total recoverable molybdenum in most waters, wastewa-
ters, and brines by atomic absorption spectroscopy.
4. Summary of Test Method
1.2 This test method is applicable in the range from 1 to 25
4.1 Molybdenum is determined by atomic-absorption spec-
μg/L of molybdenum. The range may be extended by dilution
trophotometry. The element is chelated with
of the sample.
8-hydroxyquinoline, extracted with methyl isobutyl ketone,
1.3 This test method has been used successfully with natural
and the extract aspirated into the nitrous oxide-acetylene flame
and reagent waters. It is the user’s responsibility to ensure the
of the spectrophotometer.
validity of this test method for waters of untested matrices.
1.4 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 Molybdenum can be found in waste that results from
responsibility of the user of this standard to establish appro-
chemical cleaning of components in which the metal is alloyed.
priate safety and health practices and determine the applica-
5.2 NPDES permits or other standards, or both, require
bility of regulatory limitations prior to use. For specific
monitoring pollutants in waste discharged onto the water shed
precautionary statements, see Note 3 and Note 9.
of, or into, navigable waters, and those disposed of in such a
manner that eventual contamination of underground water
2. Referenced Documents
could result.
2.1 ASTM Standards:
5.3 This test method affords an accurate and sensitive means
D 1129 Terminology Relating to Water
3 of determining compliance/noncompliance with those permits.
D 1193 Specification for Reagent Water
D 2777 Practice for Determination of Precision and Bias of
6. Interferences
Applicable Test Methods of Committee D-19 on Water
6.1 Vanadium (V) and iron (III) enhance the absorption,
D 3370 Practices for Sampling Water from Closed Con-
while chromium (VI) and tungsten (VI) suppress it. These
duits
interferences are eliminated by the addition of ascorbic acid.
D 4691 Practice for Measuring Elements in Water by Flame
Atomic Absorption Spectrophotometry 7. Apparatus
D 4841 Practice for Estimation of Holding Time for Water
7.1 Atomic-Absorption Spectrophotometer, for use at 313.3
Samples Containing Organic and Inorganic Constituents
nm. A general guide for the use of flame atomic absorption
applications is given in Practice D 4691.
3. Terminology
NOTE 1—The manufacturer’s instructions should be followed for all
3.1 Definitions—For definitions of terms used in this test
instrumental parameters.
method, refer to Terminology D 1129.
3.2 Definition of Term Specific to This Standard:
7.1.1 Molybdenum Hollow-Cathode Lamp.
3.2.1 total recoverable molybdenum—an arbitrary analyti-
7.2 Pressure-Reducing Valves—The supplies of fuel and
oxidant shall be maintained at a pressure somewhat higher than
the controlled operating pressure of the instrument by suitable
This test method is under the jurisdiction of ASTM Committee D-19 on Water
valves.
and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents
in Water.
8. Reagents and Materials
Current edition approved June 15, 1992. Published October 1992. Originally
published as D 3372 – 75. Last previous edition D 3372 – 86.
8.1 Purity of Reagents—Reagent grade chemicals shall be
Chau, Y. K., and Lum-Shue-Chan, K., “Atomic Absorption Determination of
used in all tests. Unless otherwise indicated, it is intended that
Microgram Quantities of Molybdenum in Lake Waters,” Analytica Chimica Acta,
all reagents shall conform to the specifications of the Commit-
Vol 48, 1969, p. 205.
Annual Book of ASTM Standards, Vol 11.01. tee on Analytical Reagents of the American Chemical Society,
D 3372
where such specifications are available. Other grades may be lene cylinders, will affect analytical results. Generally, replac-
used, provided it is first ascertained that the reagent is of ing the acetylene cylinder with 50 psig (345 kPa) remaining
sufficiently high purity to permit its use without lessening the prevents acetone interference; however it has been reported
accuracy of the determination. that cylinders with pressure at 100 psig (670 kPa) or greater
8.2 Purity of Water—Unless otherwise indicated, references will cause interference.
to water shall be understood to mean reagent water conforming
NOTE 3—Warning: “Purified” grade acetylene contains a special
to Specification D 1193, Type I, II, or III water. Type I is
proprietary solvent rather than acetone and should not be used. It can
preferred and more commonly used. Type II water was
weaken the walls of poly(vinyl chloride) tubing that carries the acetylene
specified at the time of round robin testing of these test to the burner, causing a potentially hazardous situation.
methods.
9. Sampling
NOTE 2—The user must ensure the type of reagent water chosen is
9.1 Collect the sample in accordance with Practices D 3370.
sufficiently free of interferences. The water should be analyzed using the
The holding time for the samples may be calculated in
test method.
accordance with Practice D 4841.
8.3 Ascorbic Acid Solution (10 g/L)—Dissolve1gof
9.2 To preserve the samples add concentrated HNO (sp gr
ascorbic acid in water and dilute to 100 mL.
1.42) to a pH of 2 or less immediately at the time of collection;
8.4 Bromphenol Blue Indicator Solution (1 g/L)—Dissolve
normally about 2 mL/L is required. If only dissolved molyb-
0.1 g of bromphenol blue in 100 mL of 50 % ethanol or
denum is to be determined, filter the samples at time of
isopropanol.
collection through a 0.45-μm membrane filter before acidifica-
8.5 Hydrochloric Acid (1 + 49)—Mix 20.0 mL of concen-
tion.
trated hydrochloric acid (HCl, sp gr 1.19) with water and dilute
10. Standardization
to1L.
8.6 8-Hydroxyquinoline-Methyl Isobutyl Ketone Solution
10.1 Prepare in 200-mL volumetric flasks a blank and
(10 g/L)—Dissolve1gof 8-hydroxyquinoline in 100 mL of
sufficient standards containing from 0.0 to 2.5 μg of molybde-
methyl isobutyl ketone. Prepare fresh daily.
num by diluting 0.0 to 25.0-mL portions of the standard
8.7 Methyl Isobutyl Ketone (MIBK).
molybdenum solution to 100 mL with water.
8.8 Molybdenum Solution, Stock (1.0 mL 5 100 μg Mo)—
10.2 Proceed as directed in 11.5 to 11.11.
Dissolve 0.1500 g of molybdenum trioxide (MoO )in10mL 10.3 Construc
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