ASTM D3651-02

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Designation: D 3651 – 02
Standard Test Method for
Barium in Brackish Water, Seawater, and Brines
This standard is issued under the fixed designation D 3651; 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 4. Summary of Test Method
1.1 This test method covers the determination of soluble 4.1 This test method is dependent upon the fact that
barium ion in brackish water, sea-water, and brines by atomic metallic atoms, in the ground state, will absorb light of the
absorption spectrophotometry. samewavelengththeyemitwhenexcited.Whenradiationfrom
1.2 The actual working range of this test method is 1 to 5 a given excited element is passed through a flame containing
mg/L barium. ground state atoms of that element, the intensity of the
1.3 This test method was used successfully on artificial transmitted radiation will decrease in proportion to the amount
brine samples. It is the user’s responsibility to ensure the of the ground state element in the flame. A hollow-cathode
validity of this test method for waters of untested matrices. lamp whose cathode is made of the element to be determined
1.4 This standard does not purport to address all of the provides the radiation.
safety concerns, if any, associated with its use. It is the 4.2 The metal atoms to be measured are placed in the
responsibility of the user of this standard to establish appro- beam of radiation by aspirating the specimen into an oxidant-
priate safety and health practices and determine the applica- fuel flame. A monochromator isolates the characteristic radia-
bility of regulatory limitations prior to use. tion from the hollow-cathode lamp and a photosensitive device
measures the attenuated transmitted radiation.
2. Referenced Documents
4.3 Since the variable and sometimes high concentrations of
2.1 ASTM Standards:
matrix materials in the waters and brines affect absorption
D 1129 Terminology Relating to Water differently, it becomes imperative to prepare standard samples
D 1193 Specification for Reagent Water
with matrices similar to the unknown samples. This is accom-
D 2777 Practice for Determination of Precision and Bias of plished by preparing synthetic standard samples with similar
Applicable Methods of Committee D-19 on Water
compositions as the unknowns. The standard samples and
D 3370 Practices for Sampling Water from Closed Con-
unknown samples are aspirated, the absorption readings re-
duits corded, a calibration curve for the standard samples con-
D 4691 Practice for Measuring Elements inWater by Flame
structed, and the original sample concentration calculated.
Atomic Absorption Spectrophotometry
5. Significance and Use
D 4841 Practice for Estimation of Holding Time for Water
Samples Containing Organic and Inorganic Constituents 5.1 Since water containing acid-soluble barium compounds
D 5810 Guide for Spiking into Aqueous Samples is known to be toxic, this test method serves the useful purpose
D 5847 Practice for the Writing Quality Control Specifica- of determining the barium in brackish water, seawater, and
tions for Standard Test Methods for Water Analysis brines.
3. Terminology
3.1 For definitions of terms used in this test method, refer to
Fletcher,G.F.andCollins,A.G.,AtomicAbsorptionMethodsofAnalysisofOil
Terminology D 1129.
Field Brines: Barium, Calcium, Copper, Iron, Lead, Lithium, Magnesium, Manga-
nese, Potassium, Sodium, Strontium, and Zinc, U. S. Bureau of Mines, Report of
Investigations 7861, 1974, 14 pp. Collins,A. G., Geochemistry of Oil Field Waters,
This test method is under the jurisdiction of ASTM Committee D19 on Water Elsevier Publishing Co., Amsterdam, The Netherlands, 1974.
and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents Angino, E. E. and Billings, G. K., Atomic Absorption Spectrophotometry in
in Water. Geology, Elsevier Publishing Co., NewYork, NY1967. Dean, J.A. and Rains,T.C.,
Current edition approved Jan. 10, 2002. Published April 2002. Originally Editors, Flame Emission and Atomic Absorption Spectrophotometry, Vol. 1, Theory,
published as D 3651 – 78. Last previous edition D 3651 – 96. 1969, Vol 2, Components, 1971, and Vol 3, Elements and Matrices, 1975, Marcel
Annual Book of ASTM Standards, Vol 11.01. Dekker, New York, NY.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3651 – 02
6. Interferences 8.4 Barium Solution, Standard (1 mL = 0.1 mg Ba)—Add
100 mLof barium solution stock to 50 mLof concentrated HCl
6.1 Ionization interference is controlled by adding potas-
(sp gr, 1.19) and about 600 mL of water. Dilute the solution to
sium.
1 L with water. One millilitre of this solution contains 0.1 mg
6.2 Matrix interferences, caused by high concentrations of
of barium.
varied ions, and spectral interference, caused by high calcium
8.5 Potassium Solution (1 mL = 10 mg K)—Dissolve 19.07
concentrations, are controlled by matching the matrices.
gofpotassiumchloride(KCl)inabout700mLofwater.Dilute
6.3 This test method is subject to calcium interference, but
the solution to 1 L with water. One millilitre of this solution
the procedure provided eliminates the interference effect of up
contains 10 mg of potassium. A purchased stock solution of
to 750 mg/L calcium. Calcium interference can also be
adequate purity is also acceptable.
minimized by using a secondary wavelength of 455.4 nm.
8.6 Calcium Solution (1 mL = 10 mg Ca)—Dissolve 54.66
6.4 In high sulfate waters, such as seawater, barium will be
g of calcium chloride hexahydrate (CaCl ·6H O) in 500 mLof
2 2
precipitatedasbariumsulfateandwillnotbepresentassoluble
water. Dilute the solution to 1 L with water. One millilitre of
barium and will, therefore, be below the detection limit of the
this solution contains 10 mg of calcium. A purchased stock
test method.
solution of adequate purity is also acceptable.
7. Apparatus 8.7 Sodium Solution (1 mL = 10 mg Na)—Dissolve 25.14 g
sodium chloride (NaCl) in 500 mLof water. Dilute the solution
7.1 AtomicAbsorption Spectrophotometer—for use at 553.6
to 1 Lwith water. One millilitre of this solution contains 10 mg
nm. A general guide for the use of flame atomic absorption
of sodium. A purchased stock solution of adequate purity is
applications is given in Practice D 4691.
also acceptable.
NOTE 1—The manufacturer’s instructions should be followed for all
8.8 Oxidant:
instrumental parameters. Wavelengths other than 553.6 nm may be used
8.8.1 Nitrous Oxide is the oxidant required for this test
only if they have been determined to be equally suitable.
method.
7.1.1 Multielement Hollow-Cathode Lamps are available
8.9 Fuel:
and have been found satisfactory.
8.9.1 Acetylene—Standard, commercially available acety-
7.2 Pressure-Reducing Valves—The supplies of fuel and
lene is the usual fuel. Acetone, always present in acetylene
oxidant shall be maintained at pressures somewhat higher than
cylinders, can be prevented from entering and damaging the
the controlled operating pressure of the instrument by suitable
burner head by replacing a cylinder which has only 690 kPa
valves.
(100 psig) of acetylene remaining.
8. Reagents and Materials
9. Sampling
8.1 Purity of Reagents—Reagent grade chemicals shall be
9.1 Collect the sample in accordance with Practices D 3370
used in all tests. Unless otherwise indicated, it is intended that
and D 4841.
all reagents shall conform to the specifications of the Commit-
9.2 Add 2.0 mL of HCl per litre of water to prevent
tee on Analytical Reagents of the American Chemical Soci-
precipitation of soluble barium.
ety, wheresuchspecificationsareavailable.Othergradesmay
be used, provided it is first ascertained that the reagent is of
10. Calibration and Standardization
sufficiently high purity to permit its use without lessening the
10.1 Prepare standards of 0.0, 1.0, 2.5, 5.0, and 10 mg/L of
accuracy of the determination.
Ba by adding 0, 1.0, 2.5, 5.0, and 10 mL of barium standard
8.2 Unless otherwise indicated, reference to water shall be
solution to 100-mL volumetric flasks.
understood to mean reagent water conforming to Specification
10.2 Add to each standard 5 mL of concentrated HCl (sp gr
D 1193, Type I. Other reagent water types may be used
1.19) 10 mL of potassium solution, (1 mL = 10 mg of K), 7.5
provided it is first ascertained that the water is of sufficiently
mL of calcium solution (1 mL = 10 mg of Ca), and 15 mL of
high purity to permit its use without adversely affecting the
sodium solution (1 mL = 10 mg of Na). Dilute these solutions
precision and bias of the test method. Type III water was
to 100 mL with water.
specified at the time of round-robin testing of this test method.
10.3 The method of operation varies with different models
8.3 Barium Solution, Stock (1 mL = 1 mg Ba)—Dissolve
of atomic absorption spectrophotometers. Therefore, no at-
1.779 g of barium chloride (BaCl ·2H O) in 50 mL of
2 2
tempt is made here to describe in detail the steps for placing an
concentrated hydrochloric acid (HCl) (sp gr 1.19) and about
instrument into operation. However, the parameters that follow
700 mL of water. Dilute the solution to 1 L with water. One
have been found suitable for some types of equipment.
millilitre of this solution contains 1 mg of barium.Apurchased
10.3.1 Turn on the instrument.
stock solution of adequate purity is also acceptable.
10.3.2 Apply the current to the cathode lamp as suggested
bythemanufacturer:Allowtheinstrumenttowarmupuntilthe
energy source stabilizes. The time required is from 10 to 20
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
min.
listed by the American Chemical Society, see Analar Standards for Laboratory
10.3.3 Ignite an air-acetylene flame. Increase the fuel flow
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
until the flame is luminescent. Let the flame stabilize (about
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. 10–15 s). Switch to the nitrous oxide. Provide concentration of
D 3651 – 02
TABLE 1 Determination of Precision and Bias
metal in accordance with the instructions outlined by the
manufacturer, to give maximum sensitivity. Statistically
Amount Amount
Bias, Significant
Added, Found, S S
10.3.4 Let the fuel-oxidant mixture burn for 10 to 15 min T O
6 % (95 % confi-
mg/L mg/L
before operating the instrument. dence level)
53.0 53.3 4.9 4.11 + 0.43 no
10.4 Operate the instrument in the absorption mode and
98.0 94.9 9.3 9.21 −3.19 no
aspirate the 0 mg/L barium standard and
...