ASTM D1253-86(1996)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
Designation:D 1253–86 (Reapproved 1996)
Standard Test Method for
Residual Chlorine in Water
This standard is issued under the fixed designation D 1253; 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 (ϵ) 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 3. Terminology
1.1 This test method covers the determination of residual 3.1 Definitions: For definitions of terms used in this test
chlorine in water by direct amperometric titration. method, refer to Terminology D 1129D 1129.
1.2 Within the constraints specified in Section 6, this test 3.2 Definitions of Terms Specific to This Standard:
method is not subject to commonly encountered interferences 3.2.1 combined residual chlorine,, n—residual consisting of
and is applicable to most waters. Some waters, however, can chlorine combined with ammonia nitrogen or nitrogenous
exert an iodine demand, usually because of organic material, compounds.
making less iodine available for measurement by this test 3.2.2 free available chlorine residual,, n—residual consist-
method. Thus, it is possible to obtain falsely low chlorine ing of hypochlorite ions, hypochlorous acid, or a combination
readings, even though the test method is working properly, thereof.
without the user’s knowledge. 3.2.3 total residual chlorine (chlorine residual),, n—the
1.3 Precision data for this test method were obtained on amount of available chlorine-induced oxidants present in water
estuary, inland main stem river, fresh lake, open ocean, and at any specified period, subsequent to the addition of chlorine.
fresh cooling tower blowdown water. Bias data could not be
NOTE 2—Chlorine present as chloride is neither included in these terms
determined because of the instability of solutions of chlorine in
nor determined by this test method.
water. It is the user’s responsibility to ensure the validity of the
NOTE 3—Bromine, bromine combined with ammonia or nitrogenous
test method for untested types of water.
compounds, and chlorine dioxide are not distinguished by this test method
from the corresponding chlorine compounds.
1.4 In the testing by which this standard was validated, the
direct and back starch-iodide titrations and the amperometric
4. Summary of Test Method
back titration, formerly part of this standard, were found to be
4.1 This is an amperometric titration test method utilizing
unworkable and were discontinued in 1986. Historical infor-
phenylarsine oxide as the titrant. When the titrator cell is
mation is presented in Appendix X1.
immersedinasamplecontainingchlorine,currentisgenerated.
NOTE 1—Orthotolidinetestmethodshavebeenomittedbecauseofpoor
As phenylarsine oxide is added, the chlorine is reduced and the
precision and accuracy.
generation of current ceases. When chlorine is present as a
1.5 This standard does not purport to address all of the
chloramine, potassium iodide is added, releasing iodine, which
safety concerns, if any, associated with its use. It is the
is titrated in a similar manner. The iodine content is calculated
responsibility of the user of this standard to establish appro-
in terms of free chlorine.
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use.
5.1 Chlorine is used to destroy or deactivate a variety of
2. Referenced Documents
unwanted chemicals and microorganisms in water and waste-
2.1 ASTM Standards:
water.
D 1129 Terminology Relating to Water
5.2 An uncontrolled excess of chlorine in water, whether
D 1193 Specification for Reagent Water
free available or combined, can adversely affect the subsequent
D 3370 Practices for Sampling Water from Closed Con-
use of the water.
duits
6. Interferences
6.1 This test method is not subject to interferences from
This test method is under the jurisdiction ofASTM Committee D-19 on Water,
and is the direct responsibility of Subcommittee D 19.05 on Inorganic Constituents temperature, color, or turbidity of sample.
in Water.
6.2 Values of pH above 8.0 interfere by slowing the reaction
Current edition approved Feb. 28, 1986. Published April 1986. Originally
rate. Buffering the sample to pH 7.0 or less eliminates the
published as D 1253 – 53. Last previous edition D 1253 – 76.
interference.
Annual Book of ASTM Standards, Vol 11.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
D 1253–86 (1996)
FIG. 1 Wiring Diagram of Amperometric Titrator
6.3 Erratic behavior of the apparatus in the presence of 7. Apparatus
,
3 4
cupric ions has been reported.
7.1 Amperometric Titration Apparatus —Refer to Fig. 1.
6.4 Cuprous and silver ions tend to poison the electrode of
NOTE 4—When the titrator has been out of service for a day or more,
the titrator.
check the electrode for sensitivity by noting the rapidity of the pointer
6.5 Nitrogen trichloride and some N-chloro compounds are
deflection. If the pointer responds slowly after the addition of KI solution,
add a small amount of biiodate. If it responds slowly to free available
often present as products of the chlorination of wastewaters
chlorine, sensitize it by adding chlorine.
and will titrate partially as free available chlorine and partially
as combined residual chlorine. This error can be avoided only
7.2 Glassware—Condition with water containing at least 10
in the determination of total residual chlorine. mg/L of residual chlorine for at least 2 h prior to use and then
rinse thoroughly.
6.6 Exposure to high concentrations of free available chlo-
rine causes a film-type polarization that reverses very slowly.
8. Reagents and Materials
This can be avoided by diluting the sample with water to less
than 10 mg/L of free available chlorine.
8.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
6.7 If chlorine dioxide is present, an unknown portion
all reagents shall conform to the specifications of the Commit-
titrates as free available chlorine.Total chlorine dioxide titrates
tee onAnalytical Reagents of theAmerican Chemical Society.
as total residual chlorine.
6.8 Depending upon final pH, chlorination of waters con-
taining ammonia or nitrogenous organic compounds can pro-
Water and Sewage Works, May 1949, p. 171, and Journal American Water
duce high concentrations of dichloramine. This compound
Works Association, Vol 34, 1942, pp. 1227–1240.
produces four to five times as much current as monochloram-
Amperometrictitratorsareavailablecommerciallyfrommostlaboratorysupply
ine. The current produced by as little as 5 mg/L of dichloram-
houses.
inecancausethemicroammeterpointertoreadoffscaleevenat
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
the end point in the titration of free available chlorine. This
listed by the American Chemical Society, see Analar Standards for Laboratory
may be overcome by use of an opposing voltage in the
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
apparatus’ circuitry. The instrument’s manufacturer should be
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
consulted in this regard. MD.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Please contact ASTM International (www.astm.org) for the latest information.
D 1253–86 (1996)
Other grades may be used, provided it is first ascertained that to the right or high current side of the scale so the pointer can
the reagent is of sufficiently high purity to permit its use deflect counterclockwise during the analysis.
without lessening the accuracy of the determination. 10.2.3 Titrate using standard phenylarsine oxide solution,
8.2 Purity of Water—Unless otherwise indicated, references addingthetitrantinsmallincrements,andnotingthedeflection
to water shall be understood to mean reagent water conforming of the microammeter pointer. Plot the progress of the titration
to Specification D 1193D 1193, Type III, further treated to be on line
...