ASTM D3868-95(1999)

Standard Test Method for Fluoride Ions in Brackish Water, Seawater, and Brines

SCOPE
1.1 This test method  covers the determination of soluble fluoride ions in brackish water, seawater and brines by use of a fluoride selective electrode.  
1.2 Samples containing from 1.0 to 25 mg/L can be analyzed by this test method.  
1.3 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.

General Information

• Status: Historical
• Publication Date: 09-Jun-1999
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Replaced By: ASTM D3868-04 - Standard Test Method for Fluoride Ions in Brackish Water, Seawater, and Brines
• Effective Date: 01-Mar-2004

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
An American National Standard
Designation: D 3868 – 95 (Reapproved 1999)
Standard Test Method for
Fluoride Ions in Brackish Water, Seawater, and Brines
This standard is issued under the fixed designation D 3868; 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 5. Significance and Use
1.1 This test method covers the determination of soluble 5.1 Identification of a brackish water, seawater, or brine is
fluoride ions in brackish water, seawater and brines by use of determined by comparison of the concentrations of their
a fluoride selective electrode. dissolved constituents. The results are used to evaluate the
1.2 Samples containing from 1.0 to 25 mg/L can be ana- origin of the water, determine if it is a possible pollutant, or if
lyzed by this test method. it is related to a potential source of a valuable mineral. For
1.3 This standard does not purport to address all of the example, in geochemical studies some correlation data indicate
safety concerns, if any, associated with its use. It is the that fluoride is an indirect indicator of the presence of lithium.
responsibility of the user of this standard to establish appro-
6. Interferences
priate safety and health practices and determine the applica-
6.1 Metal ions such as aluminum and iron (III) interfere
bility of regulatory limitations prior to use.
with the fluoride determination by forming complexes with
2. Referenced Documents
fluoride ions. The buffer solution contains a complexing agent
2.1 ASTM Standards: that preferentially complexes these metal ions. This solution
D 1129 Terminology Relating to Water also contains a pH buffer to reduce electrode interference from
D 1193 Specification of Reagent Water hydroxide ions and to prevent the formation of HF. Sodium
D 2777 Practice for Determination of Precision and Bias of chloride is added as ionic strength adjustor. Increasing amounts
Applicable Methods of Committee D-19 on Water of aluminum, iron (III), and borate ions were added to 1.5
D 3370 Practices for Sampling Water from Closed Con- mg/L fluoride solutions and were found not to interfere up to 5,
duits 350, and 250 mg/L (as boron), respectively.
3. Terminology 7. Apparatus
3.1 Definitions—For definitions of terms used in this test 7.1 Millivoltmeter (accurate to 6 0.1 mV), specific ion
method, refer to Terminology D 1129. meter.
7.2 Fluoride Selective Electrode, reference electrode.
4. Summary of Test Method
7.3 Microlitre Pipets.
4.1 A fluoride selective electrode, reference electrode, and
8. Reagents
millivoltmeter are used to determine fluoride in brine samples
by a standard addition method. 8.1 Purity of Reagents—Reagent grade chemicals shall be
4.2 The fluoride selective electrode consists of a lanthanum used in all tests. Unless otherwise indicated, it is intended that
fluoride crystal that develops an electrode potential corre- all reagents shall conform to the specification of the Committee
sponding to the level of fluoride ion in solution. on Analytical Reagents of the American Chemical Society,
where such specifications are available. Other grades may be
used, provided it is first ascertained that the reagent is of
This test method is under the jurisdiction of ASTM Committee D-19 on Water
sufficiently high purity to permit its use without lessening the
and is the direct responsibility of Subcommitee D19.05 on Inorganic Constituents in
accuracy of the determination.
Water.
Current edition approved Sept. 10, 1995. Published November 1995. Originally
published as D 3868 – 79. Last previous edition D 3868 – 94.
Additional information is contained in the following references: Hoke, S. H.,
Fletcher, G. E., and Collins, A. G., “Fluoride and Iodide Selective Electrodes
Applied to Oilfield Brine Analysis,” U.S. Department of Energy, Report of Reagent Chemicals, American Chemical Society Specifications, American
Investigations, BETC/RI-78/7. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Rix, C. J., Bond, A. M., and Smith, J. D., “District Determination of Fluoride in listed by the American Chemical Society, see Analar Standards for Laboratory
Sea Water with a Fluoride Selective Ion Electrode by a Method of Standard Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Additions,” Analytical Chemistry, Vol 48, 1976, p. 1236. and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 11.01. MD.
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