ASTM D512-89(1999)
(Test Method)Standard Test Methods for Chloride Ion In Water
Standard Test Methods for Chloride Ion In Water
SCOPE
1.1 These test methods cover the determination of chloride ion in water, wastewater (Test Method C only), and brines. The following three test methods are included: Sections Test Method A (Mercurimetric Titration) 7 to 14 Test Method B (Silver Nitrate Titration) 15 to 21 Test Method C (Ion-Selective Electrode Method) 22 to 29
1.2 Test Methods A, B, and C were validated under Prac- tice D2777-77, and only Test Method B conforms also to Practice D2777-86. Refer to Sections 14, 21, and 29 for further information.
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. For a specific hazard statement, see 26.1.1.
1.4 A former colorimetric test method was discontinued. Refer to Appendix X1 for historical information.
General Information
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Standards Content (Sample)
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Designation:D 512–89(Reapproved1999)
Standard Test Methods for
Chloride Ion In Water
This standard is issued under the fixed designation D 512; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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.
1. Scope * therefore, be measured accurately. It is highly detrimental to
high-pressure boiler systems and to stainless steel, so monitor-
1.1 These test methods cover the determination of chloride
ing is essential for prevention of damage. Chloride analysis is
ioninwater,wastewater(TestMethodConly),andbrines.The
widelyusedasatoolforestimatingthecyclesofconcentration,
following three test methods are included:
such as in cooling tower applications. Processing waters and
Sections
pickling solutions used in the food processing industries also
Test Method A (Mercurimetric Titration) 7 to14
Test Method B (Silver Nitrate Titration) 15 to 21 require dependable methods of analysis for chloride.
Test Method C (Ion-Selective Electrode Method) 22 to 29
5. Purity of Reagents
1.2 Test Methods A, B, and C were validated under Prac-
5.1 Reagent grade chemicals shall be used in all tests.
tice D2777–77, and only Test Method B conforms also to
Unlessotherwiseindicated,itisintendedthatallreagentsshall
Practice D2777–86. Refer to Sections 14, 21, and 29 for
conform to the specifications of the Committee on Analytical
further information.
Reagents of the American Chemical Society, where such
1.3 This standard does not purport to address all of the
specifications are available. Other grades may be used, pro-
safety concerns, if any, associated with its use. It is the
vided it is first ascertained that the reagent is of sufficiently
responsibility of the user of this standard to establish appro-
high purity to permit its use without lessening the accuracy of
priate safety and health practices and determine the applica-
the determination.
bility of regulatory limitations prior to use. For a specific
5.2 Purity of Water— Unless otherwise indicated, all refer-
hazard statement, see 26.1.1.
ences to water shall be understood to mean Type II reagent
1.4 A former colorimetric test method was discontinued.
water conforming to Specification D1193.
Refer to Appendix X1 for historical information.
6. Sampling
2. Referenced Documents
6.1 Collect the sample in accordance with Practice D1066
2.1 ASTM Standards:
and Practices D3370, as applicable.
D1066 Practice for Sampling Steam
D1129 Terminology Relating to Water
TEST METHOD A—MERCURIMETRIC
D1193 Specification for Reagent Water
TITRATION
D2777 Practice for Determination of Precision and Bias of
Applicable Methods of Committee D-19 on Water
7. Scope
D3370 Practices for Sampling Water from Closed Con-
7.1 This test method can be used to determine chloride ion
duits
in water, provided interferences are absent (see Section 9).
D4127 Terminology Used with Ion-Selective Electrodes
7.2 Though not specified in the research report, the preci-
sionstatementispresumedtohavebeenobtainedusingTypeII
3. Terminology
reagentwater.Itistheresponsibilityoftheanalysttoassurethe
3.1 Definitions—For definitions of terms used in these test
validity of this test method for untested matrices.
methods, refer to Terminologies D1129 and D4127.
7.3 This test method was validated for the concentration
4. Significance and Use
4.1 Chloride ion is under regulation in water, and must, 3
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
These test methods are under the jurisdiction of ASTM Committee D-19 on Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Water and are the direct responsibility of Subcommittee D19.05 on Inorganic and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Constituents in Water. MD.
Current edition approved Oct. 2, 1989. Published December 1989. Originally For information of interest in connection with this test method, and supporting
published as D512 – 38. Last previous edition D512 – 88. data, refer to Clark, F. E., “Determination of Chloride in Water,” Analytical
Annual Book of ASTM Standards, Vol 11.01. Chemistry, Vol 22,April 1950, pp. 553–555, and Vol 22, November 1950, p. 1458.
*ASummary of Changes section appears at the end of this standard.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 512
−
range 8.0 to 250 mg/L Cl . isstableformuchlongerperiods.Boththepowdermixture(capsuleform)
and the liquid indicator are available commercially.
8. Summary of Test Method
11.5 Nitric Acid (3+997)—Mix 3 volumes of concen-
8.1 Dilute mercuric nitrate solution is added to an acidified
trated nitric acid (HNO , sp gr 1.42) with 997 volumes of
sample in the presence of mixed diphenylcarbazone-
water.
bromophenolblueindicator.Theendpointofthetitrationisthe
11.6 pH Indicating Paper, long-range type, covering a pH
formation of the blue-violet mercury diphenylcarbazone com-
range 1 to 11.
plex.
11.7 Sodium Chloride Solution, Standard (0.025N)—Dry
several grams of sodium chloride (NaCl) for 1 h at 600°C.
9. Interferences
Dissolve 1.4613 g of the dry salt in water, and dilute to 1 Lat
9.1 Theanionsandcationsgenerallyfoundinwaterofferno
25°C in a volumetric flask.
interference. Zinc, lead, nickel, and ferrous and chromous ions
11.8 SodiumHydroxideSolution(10g/L)—Dissolve10gof
affect solution and end-point colors, but do not reduce the
sodium hydroxide (NaOH) in water and dilute to 1 L.
accuracy of the titration when present in concentrations up to
100 mg/L. Copper is tolerable up to 50 mg/L. Titration in the
12. Procedure
presence of chromate ion requires indicator with extra back-
12.1 Use a volume of sample such that it will contain not
ground color (alphazurine) and prior reduction for concentra-
more than 20 mg of chloride ion, diluting the sample with
tions above 100 mg/L. Ferric ion above 10 mg/L must be
water to approximately 50-mLvolume if necessary. Determine
reduced before titration, and sulfite ion must be oxidized.
an indicator blank on 50 mL of chloride-free water, applying
Bromide and fluoride will be partially titrated with the chlo-
the same procedure followed for the sample.
ride. Quaternary ammonium salts also interfere if present in
12.2 Add 5 to 10 drops of mixed indicator solution, and
significant amounts (1 to 2 mg/L). Deep color may also
shake or swirl the flask. If a blue-violet or red color develops,
interfere.
add HNO (3+997) dropwise until the color changes to
yellow. Add 1 mL of excess acid. If a yellow or orange color
10. Apparatus
forms immediately on addition of the mixed indicator, add
10.1 Microburet, 1 or 5-mL, with 0.01-mL graduation
NaOH solution (10 g/L) dropwise until the color changes to
intervals.
blue-violet; then add HNO (3+997) dropwise until the color
changes to yellow and further add 1 mL excess of acid (Note
11. Reagents and Materials
4).
11.1 Hydrogen Peroxide (30% H O ).
2 2
NOTE 4—The prescribed acidification provides a satisfactory pH range
11.2 Hydroquinone Solution (10 g/L)—Dissolve 1 g of
from 3.0 to 3.5. Acidified samples on which electrometric pH measure-
purified hydroquinone in water and dilute to 100 mL.
ments have been made shall not be used for chloride determinations,
11.3 Mercuric Nitrate Solution, Standard (0.025N)—
becausetheuseofthecalomelreferenceelectrodemayintroduceerrordue
Dissolve 4.2830 g of mercuric nitrate (Hg(NO ) ·H O) in 50
3 2 2 tochloridecontamination.ForprecisepHadjustmentofsampleshavinga
mL of water acidified with 0.5 mL of concentrated nitric acid
low-chloride concentration, instrumental measurements may be made on
one sample aliquot to determine treatment needed for another to be used
(HNO , sp gr 1.42). Dilute the acidified Hg(NO ) solution
3 3 2
for the chloride test.
with water to 1 L. Filter if necessary, and standardize against
the standard sodium chloride (NaCl) solution, using the pro-
12.3 Titratethesolutionandablankwith0.025NHg(NO )
3 2
cedure described in Section 12 (see Note 1).
solution until a blue-violet color, as viewed by transmitted
light, persists throughout the solution (Note 5). Record the
NOTE 1—Sharpness of End Point—The end point, while sharp, can be
millilitres of Hg(NO ) solution added in each case.
improved somewhat for certain types of water by adding several drops of
3 2
a 0.05-g/L solution of xylene cyanole FF or alphazurine blue-green dye
NOTE 5—The use of indicator modifications and the presence of heavy
(color index 714) to the titration sample.
metal ions can change solution colors without affecting accuracy of the
11.4 Mixed Indicator Solution —Dissolve 0.5 g of crystal- determination. For example, solutions containing alphazurine may be
bright blue when neutral, grayish purple when basic, blue-green when
line diphenylcarbazone and 0.05 g of bromophenol blue
acidic, and blue-violet at the chloride end point. Solutions containing
powderin75mLofethylalcohol(95%),anddiluteto100mL
about 100 mg/L nickel ion and normal mixed indicator are purple when
with the alcohol (Note 2). Store in a brown bottle and discard
neutral, green when acid, and gray at the chloride end point. When
after 6 months (Note 3).
applying this test method to samples that contain colored ions or that
requiremodifiedindicator,itisrecommendedthattheoperatorbefamiliar
NOTE 2—Methanol, isopropanol, or ethanol denatured with either
with the specific color changes involved by experimenting with solutions
methanol or isopropanol (Formula 3A) may be used if pure ethyl alcohol
prepared as standards for comparison of color effects.
is not available. Other denatured ethanol formulae are not suitable.
NOTE 3—Liquid indicator generally deteriorates to the point that it
12.4 If chromate ion is present in the absence of iron and in
yields no end-point color after 12 to 18 months of storage. High
concentrationlessthan100mg/L,usethealphazurinemodified
temperature (above 37.8°C (100°F)) and exposure to bright light may
mixedindicator(Note1)andacidifythesampleasdescribedin
shortenstoragelife.Adrypowdermixtureofthetwoindicatoringredients
12.2buttopH3asindicatedbypHindicatingpaper.Titratethe
solution as described in 12.3, but to an olive-purple end point.
12.5 If chromate ion is present in the absence of iron and in
This diphenylcarbazone 1-bromophenol blue indicator is covered by U.S.
Patent No. 2,784,064. concentration greater than 100 mg/L, add 2 mL of fresh
D 512
hydroquinone solution and proceed as described in 12.2 and collaborative testing. Under the allowances made in 1.5 of
12.3. Practice D2777–86, these precision and bias data do meet
12.6 If ferric ion is present in the absence or presence of existing requirements for interlaboratory studies of Committee
chromate ions, use a sample of such volume as to contain no D–19 test methods.
more than 2.5 mg of ferric ion or of ferric ion plus chromate
TEST METHOD B—SILVER NITRATE TITRATION
ion.Add 2 mLof fresh hydroquinone solution, and proceed as
described in 12.2 and 12.3.
15. Scope
12.7 If sulfite ion is present, add 0.5 mLof H O to 50 mL
2 2 7
15.1 Thistestmethod isintendedprimarilyforwaterwhere
of the sample in the Erlenmeyer flask and mix for 1 min.Then
thechloridecontentis5mg/Lormore,andwhereinterferences
proceed as described in 12.2 and 12.3.
suchascolororhighconcentrationsofheavymetalionsrender
Test Method A impracticable.
13. Calculation
15.2 Though not specified in the research report, the preci-
13.1 Calculate the chloride ion concentration, in milligrams
sion and bias statement is presumed to have been obtained
per litre, in the original sample as follows:
using Type II reagent water. It is the responsibility of the
Chloride,mg/L5@~V 2V !3N335453#/S
1 2 analyst to assure the validity of this test method for untested
matrices.
where:
15.3 This test method was validated for the concentration
V 5 standard Hg(NO ) solution required for titration of
1 3 2
−
range 8.0 to 250 mg/L Cl .
the sample, mL,
V 5 standard Hg(NO ) solution required for titration of
2 3 2
16. Summary of Test Method
the blank, mL,
16.1 WateradjustedtoapproximatelypH8.3istitratedwith
N 5 normality of the Hg(NO ) solution, and
3 2
silver nitrate solution in the presence of potassium chromate
S 5 sample used in 12.1, mL.
indicator. The end point is indicated by persistence of the
brick-red silver chromate color.
14. Precision and Bias
14.1 PrecisionStatement—Theprecisionofthistestmethod
17. Interferences
may be expressed as follows:
17.1 Bromide, iodide, and sulfide are titrated along with the
S 5 0.023X10.43
T
chloride. Orthophosphate and polyphosphate interfere if
S 50.002X10.46
present in concentrations greater than 250 and 25 mg/L,
O
respectively. Sulfite and objectionable color or turbidity must
where:
beeliminated.CompoundswhichprecipitateatpH8.3(certain
S 5 overall precision, mg/L,
T
hydroxides) may cause error by occlusion.
S 5 single-operator precision, mg/L, and
O
X 5 concentration of chloride ion determined.
18. Reagents
14.2 Bias Statement— Recoveries of known amounts of
18.1 Hydrogen Peroxide (30%) (H O ).
2 2
chloride were as follows:
18.2 Phenolphthalein Indicator Solution (10 g/L)—Prepare
Statistically
as directed in Methods E200.
Amount Added, Amount Found, Significant (95 %
18.3 Potassium Chromate Indicator Solution—Dissolve 50
mg/L mg/L 6 % Bias Confidence Level)
250 248 −0.80 no
g of potassium chromate (K CrO ) in 100 mL of water, and
2 4
80.0 79.3 −0.88 no
add silver nitrate (AgNO ) until a slight red precipitate is
8.00 7.51 −6.13 yes
produced.Allowthesolutiontostand,protectedfromlight,for
14.3 The information presented in 14.1 and 14.2 is derived
at least 24 h after the addition of AgNO . Then filter the
from round-robin testing in which five laboratories, including
solutiontoremovetheprecipitate,anddiluteto1Lwithwater.
seven operators, participated. Though not clearly specified in
18.4 Standard Solution, Silver Nitrate (0.025 N)—Crush
the test report, the matrix is presumed to be Type II reagent
approximately5gofsilvernitrate(AgNO )crystalsanddryto
water. Of seven data sets ranked as described in Practice
constant weight at 40°C. Dissolve 4.2473 g of the crushed,
D2777, none was rejected, nor were any data points deter-
driedcrystalsinwateranddiluteto1L.Standardizeagainstthe
minedtobe“o
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