ASTM D1179-16(2021)e1
(Test Method)Standard Test Methods for Fluoride Ion in Water
Standard Test Methods for Fluoride Ion in Water
SIGNIFICANCE AND USE
4.1 Simple and complex fluoride ions are found in natural waters. Fluoride forms complexing ions with silicon, aluminum, and boron. These complexes may originate from the use of fluorine compounds by industry.
4.2 Fluoridation of drinking water to prevent dental caries is practiced by a large number of communities in this country. Fluoride is monitored to assure that an optimum treatment level, usually near 1 mg/L, is maintained.
SCOPE
1.1 These test methods2 cover the determination of fluoride ion in water. The following two test methods are given:
Sections
Test Method A—Distillation
7 to 13
Test Method B—Ion Selective Electrode
14 to 21
1.2 Test Method A covers the accurate measurement of total fluoride in water through isolation of the fluoride by distillation and subsequent measurement in the distillate by use of the ion selective electrode (ISE) method. The procedure covers the range from 0.1 to 2.6 mg/L of fluoride.
1.3 Test Method B covers the accurate measurement of simple fluoride ion in water by means of an ion selective electrode. With this test method, distillation is eliminated because the electrode is not affected by the interferences common to colorimetric procedures. Concentrations of fluoride from 0.1 to 1000 mg/L may be measured.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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. For a specific precautionary statement, see 12.1.2.
1.6 Former Test Method A, SPADNS Photometric Procedure, was discontinued. Refer to Appendix X1 for historical information.
1.7 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.
General Information
Relations
Standards Content (Sample)
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: D1179 − 16 (Reapproved 2021)
Standard Test Methods for
Fluoride Ion in Water
This standard is issued under the fixed designation D1179; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—The WTO caveat was added editorially in December 2021.
1. Scope Development of International Standards, Guides and Recom-
2 mendations issued by the World Trade Organization Technical
1.1 These test methods cover the determination of fluoride
Barriers to Trade (TBT) Committee.
ion in water. The following two test methods are given:
Sections
2. Referenced Documents
Test Method A—Distillation 7 to 13
Test Method B—Ion Selective Electrode 14 to 21 2.1 ASTM Standards:
D1066 Practice for Sampling Steam
1.2 Test MethodAcovers the accurate measurement of total
D1129 Terminology Relating to Water
fluorideinwaterthroughisolationofthefluoridebydistillation
D1193 Specification for Reagent Water
and subsequent measurement in the distillate by use of the ion
D2777 Practice for Determination of Precision and Bias of
selective electrode (ISE) method. The procedure covers the
Applicable Test Methods of Committee D19 on Water
range from 0.1 to 2.6 mg/L of fluoride.
D3370 Practices for Sampling Water from Flowing Process
1.3 Test Method B covers the accurate measurement of
Streams
simple fluoride ion in water by means of an ion selective
D4127 Terminology Used with Ion-Selective Electrodes
electrode. With this test method, distillation is eliminated
D5810 Guide for Spiking into Aqueous Samples
because the electrode is not affected by the interferences
D5847 Practice for Writing Quality Control Specifications
commontocolorimetricprocedures.Concentrationsoffluoride
for Standard Test Methods for Water Analysis
from 0.1 to 1000 mg/L may be measured.
3. Terminology
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3.1 Definitions:
standard.
3.1.1 For definitions of terms used in this standard, refer to
Terminologies D1129 and D4127.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Significance and Use
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 4.1 Simple and complex fluoride ions are found in natural
mine the applicability of regulatory limitations prior to use. waters. Fluoride forms complexing ions with silicon,
For a specific precautionary statement, see 12.1.2. aluminum,andboron.Thesecomplexesmayoriginatefromthe
1.6 Former Test Method A, SPADNS Photometric use of fluorine compounds by industry.
Procedure, was discontinued. Refer to Appendix X1 for
4.2 Fluoridationofdrinkingwatertopreventdentalcariesis
historical information.
practiced by a large number of communities in this country.
1.7 This international standard was developed in accor-
Fluoride is monitored to assure that an optimum treatment
dance with internationally recognized principles on standard- level, usually near 1 mg/L, is maintained.
ization established in the Decision on Principles for the
5. Purity of Reagents
5.1 Reagent grade chemicals shall be used in all tests.
These test methods are under the jurisdiction of ASTM Committee D19 on
Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Unless otherwise indicated, it is intended that all reagents shall
Constituents in Water.
Current edition approved Nov. 1, 2021. Published December 2021. Originally
approved in 1951. Last previous edition approved in 2016 as D1179 – 16. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D1179-16R21E01. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Bellack,E.,“SimplifiedFluorideDistillationMethod,”JournaloftheAmerican Standards volume information, refer to the standard’s Document Summary page on
Water Works Association, Vol 50, 1958, p. 530. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D1179 − 16 (2021)
TABLE 1 Allowable Interference Levels with Selective Ion
A
Electrode and Buffer
Maximum Allowable Concentration at
Interfering Ion
−
1.0 mg/L F
+3
Al 0.5
+4
Si 50
+3
Fe 65
A
Refer to 16.2 for description of interfering cations.
conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such
specifications are available. Other grades may be used, pro-
vided it is first ascertained that the reagent is of sufficiently
high purity to permit its use without lessening the accuracy of
the determination.
5.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean Type I reagent water
conforming to Specification D1193. Other reagent water types
may be used provided it is first ascertained that the water is of
sufficiently high purity to permit its use without adversely
A—Heating mantle (quartz).
B—Round-bottom flask, 1000 mL.
affecting the precision and bias of the test method. Type II
C—Adapter with thermometer opening.
water was specified at the time of round robin testing of this
D—Thermometer, 200°C.
test method.
E—Connecting tube.
F—Graham condenser, 300 mm.
G—Vessel, calibrated at 300 mL.
6. Sampling
6.1 Collect the sample in accordance with Practice D1066
FIG. 1 Distillation Assembly for Fluoride Isolation
or Practices D3370, as applicable.
TEST METHOD A—DISTILLATION
9.1.1 Aluminum in excess of 300 mg/L and silicon dioxide
7. Scope
as colloidal silica in excess of 400 mg/L will hold up in the
7.1 This test method is applicable to the accurate determi-
condenser to a certain extent, causing low results and acting as
nation of fluoride ion in water, including most wastewaters.
apositiveinterferenceforsubsequentsamplesoflowerfluoride
Samples that may require distillation include high concentra-
content. In these cases, the condenser should be flushed with
tions of fluoborate or fluoboric acid (such as electroplating
300 to 400 mL of water and the washwater added to the
wastes), and samples which contain aluminum, silica, or iron
distillate. The distillate may then be diluted to 1.0 L. If the
(seeTable1).Anionssuchaschloride,bromide,iodide,sulfate,
analystprefers,asmallersamplealiquotdilutedto300mLmay
bicarbonate,nitrate,phosphateandacetatedonotinterferewith
be selected for distillation.
ISE measurement unless present at greater than about1%and
9.1.2 Sea water, brines, and generally samples of dissolved
do not necessitate distillation. This test method may not be
solids in excess of 2500 mg/L will cause bumping in the
applicable to concentrated brines and oily wastes.
distillation flask. Dilution of the sample with fluoride-free
7.2 This test method was tested on reagent water and water to a lesser-dissolved solids concentration is an effective
wastewater. It is the user’s responsibility to ensure the validity remedy to bumping.
of this test method for waters of untested matrices. 9.1.3 Samples containing oily matter which may result in a
two-phasedistillate,anemulsion,oranythingotherthanaclear
8. Summary of Test Method
distillate may prevent accurate measurement of fluoride. Such
8.1 The fluoride is distilled as hydrofluosilicic acid and is samples should be extracted initially with a suitable solvent
determined by the ion selective electrode method. (such as ether, chloroform, benzene, and similar solvents) to
remove the oily material, and then warmed on a steam bath to
9. Interferences
remove traces of the added solvent.
9.1 In sample distillation, interferences may be experienced
10. Apparatus
due to the following factors.
10.1 Distillation Assembly—Glassware consisting of a 1-L,
round bottom, borosilicate boiling flask, an adapter with a
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
thermometer opening, a connecting tube, a condenser, and a
listed by the American Chemical Society, see Analar Standards for Laboratory
thermometer reading to 200°C, assembled as shown in Fig. 1.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standard-taper or spherical ground glass joints shall be used
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
MD. throughout the apparatus.
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D1179 − 16 (2021)
TABLE 2 Determination of Precision—Final Statistics for Test
11. Reagents
Method A
11.1 Sodium Fluoride Solution, Standard (1.0 mL = 0.01
NOTE 1—Precision of Test MethodAwas determined from round robin
mg F)—Dissolve 0.2210 g of sodium fluoride (NaF) in water
data using distillation with ion selective electrode finish.
anddiluteto1.0L.Dilute100mLofthissolutionto1.0Lwith
Amount added, mg/L 0.150 0.560 0.840 2.600
water. Store in borosilicate glass or polyethylene. Alternately,
Reagent Water
commercially prepared fluoride standards of appropriate
A
Concentration, x 0.147 0.558 0.818 2.520
A
known purity may be used. S 0.033 0.053 0.034 0.099
t
A
S 0.013 0.017 0.004 0.031
o
11.2 Sulfuric Acid (H SO ), Concentrated (sp gr 1:84). Wastewater
2 4
A A
Concentration, x 0.126 0.505 0.771 2.454
A
S 0.048 0.068 0.092 0.070
t
12. Procedure A
S 0.018 0.013 0.017 0.030
o
A
Calculated with outlier point removed from data base.
12.1 Distillation:
12.1.1 Place 400 mL of water in the distilling flask and add
200 mLof concentrated H SO (sp gr 1.84). Observe the usual
2 4
TABLE 3 Determination of Bias for Test Method A
precautions while mixing the H SO by slow addition of the
2 4
NOTE 1—Bias of Test MethodAwas determined from round robin data
acid accompanied by constant swirling. Add sufficient boiling
using distillation with ion selective electrode finish.
stones andassembletheapparatusasshowninFig.1.Heatthe
Amount Mean re- Statistically
solutionintheflask,preferablywithanelectricheatingmantle,
added covery Bias % Bias significant
until the temperature of the contents reaches exactly 180°C. (A
mg/L mg/L at 5 % level
quartzheatingmantleispreferredinordertoreachtherequired
Reagent Water
180°C in a minimum time.) While heating, the tip of the 0.150 0.147 − 0.003 −2.0 % no
0.560 0.558 −0.002 −0.4 % no
thermometer must extend below the level of the liquid in the
0.840 0.818 − 0.022 −2.6 % yes
flask. Discard the distillate. The procedure, to this step, serves
2.600 2.520 − 0.080 −3.1 % yes
to adjust the acid-water ratio for subsequent distillations. Wastewater
0.150 0.126 − 0.024 − 16.0 % no
12.1.2 Caution—Cool the acid-water mixture to below
0.560 0.505 − 0.055 −9.8 % yes
100°C, slowly add 300 mL of sample, and mix thoroughly
0.840 0.771 −0.069 −8.2 % yes
2.600 2.454 − 0.146 −5.7 % yes
beforeheating.Distillasdescribedin12.1.1,untilthetempera-
ture reaches 180°C.
12.1.3 Collectthedistillateinanysuitablycalibratedvessel.
If a calibrated vessel is used, it is possible to dispense with
TEST METHOD B—ION SELECTIVE ELECTRODE
thermometer readings and stop the distillation when the vol-
ume of distillate reaches 300 mL.
14. Scope
12.1.4 Samples containing chlorides less than about1%do
14.1 This test method is applicable to the measurement of
not interfere with ISE measurements.
fluoride ion in finished waters, natural waters, and most
12.1.5 The acid-water distilling solution may be used re-
industrial wastewaters. With this test method, distillation is
peatedly until the buildup of interference materials equals the
eliminated and concentrations of fluoride from 0.1 to 1000
concentration given in Section 9.
mg/L may be measured. Concentrated solutions of fluoborate
12.2 Analysis—Use Test Method B (Ion Selective Elec-
or fluoboric acid, such as in electroplating wastes, should be
trode) with the buffer solution described in 18.1.
distilled or tested using a fluoroborate ISE. Samples which
contain aluminum, silica, or iron may require distillation (see
13. Precision and Bias
Table 1). Anions such as chloride, bromide, iodide, sulfate,
bicarbonate, nitrate, phosphate, and acetate typically do not
13.1 The precision and bias for Test Method A, shown in
interfere unless present at greater than about1%or more.
Table 2 and Table 3 were determined using distillation fol-
lowed by an ion selective electrode finish. Four concentrations
14.2 Thetestmethodisnotapplicabletosamplescontaining
and three replicates were provided by six laboratories for
more than 10 000 mg/L of dissolved solids.
reagent water and wastewater.
14.3 This test method was tested on reagent water. It is the
user’s responsibility to ensure the validity of this test method
13.2 Precision and bias for this test method conform to
Practice D2777 – 77, which was in place at the time of for waters of untested matrices.
collaborative testing. Under the allowances made in 1.4 of
15. Summary of Test Method
Practice D2777 – 13, these precision and bias data do meet
existing requirements for interlaboratory studies of Committee
15.1 The fluoride is determined potentiometrically using an
D19 test methods.
ion selective fluoride electrode in conjunction with a standard
single junction, sleeve-type reference electrode or a combina-
tion fluoride electrode. Use the electrode(s) with a pH meter
having an expanded millivolt scale, or an ISE meter having a
Glass beads must be of a soft glass (rather than borosilicate). Use about 12
beads. Soft beads will provide silica to the fluoride and protect the distillation flask. direct concentration readout.
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D1179 − 16 (2021)
TABLE 4 Determination of Precision Without Distillation using
15.2 The fluoride electrode consists of a lanthanum fluoride
Buffers
crystal across which a potential is developed by fluoride
6,7
Buffer A Buffer B
ions. The cell may be represented by Ag/AgCl, Cl (0.3), F
Concentration,
(0.001) LaF /test solution/KCl/AgCl/Ag.
3 S S S S
t o t o
mg/L
15.3 The electrode(s) is calibrated in known fluoride
0.25 0.05 0.023 0.066 0.02
2.5 0.025 0.091 0.04 0.035
solutions, and the concentrations of unknowns are determined
25 1.21 0.356 0.896 0.218
in solutions with the same background. Samples and standards
250 22.2 3.46 1.68 0.80
should be measured at the same temperature.
15.4 Standards and samples are diluted wi
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