ASTM D1293-12
(Test Method)Standard Test Methods for pH of Water
Standard Test Methods for pH of Water
SIGNIFICANCE AND USE
The pH of water is a critical parameter affecting the solubility of trace minerals, the ability of the water to form scale or to cause metallic corrosion, and the suitability of the water to sustain living organisms. It is a defined scale, based on a system of buffer solutions with assigned values. In pure water at 25°C, pH 7.0 is the neutral point, but this varies with temperature and the ionic strength of the sample. Pure water in equilibrium with air has a pH of about 5.5, and most natural uncontaminated waters range between pH 6 and pH 9.
SCOPE
1.1 These test methods cover the determination of pH by electrometric measurement using the glass electrode as the sensor. Two test methods are given as follows:
Sections Test Method APrecise Laboratory Measurement 8 to 15 Test Method BRoutine or Continuous Measurement 16 to 24
1.2 Test Method A covers the precise measurement of pH in water utilizing at least two of seven standard reference buffer solutions for instrument standardization.
1.3 Test Method B covers the routine measurement of pH in water and is especially useful for continuous monitoring. Two buffers are used to standardize the instrument under controlled parameters, but the conditions are somewhat less restrictive than those in Test Method A. For on-line measurement, also see Test Method D6569 which provides more detail.
1.4 Both test methods are based on the pH scale established by NIST (formerly NBS) Standard Reference Materials.
1.5 Neither test method is considered to be adequate for measurement of pH in water whose conductivity is less than about 5 μS/cm. Refer to Test Methods D5128 and D5464.
1.6 Precision and bias data were obtained using buffer solutions only. It is the user's responsibility to assure the validity of these test methods for untested types of water.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
Designation: D1293 − 12
Standard Test Methods for
1
pH of Water
This standard is issued under the fixed designation D1293; 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.
1. Scope 2. Referenced Documents
3
1.1 These test methods cover the determination of pH by 2.1 ASTM Standards:
electrometric measurement using the glass electrode as the D1066 Practice for Sampling Steam
sensor. Two test methods are given as follows: D1067 Test Methods for Acidity or Alkalinity of Water
D1129 Terminology Relating to Water
Sections
Test Method A—Precise Laboratory Measurement 8 to 15
D1192 Guide for Equipment for Sampling Water and Steam
Test Method B—Routine or Continuous Measurement 16 to 24 4
in Closed Conduits (Withdrawn 2003)
1.2 Test MethodAcovers the precise measurement of pH in
D1193 Specification for Reagent Water
water utilizing at least two of seven standard reference buffer
D2777 Practice for Determination of Precision and Bias of
solutions for instrument standardization.
Applicable Test Methods of Committee D19 on Water
D3370 Practices for Sampling Water from Closed Conduits
1.3 Test Method B covers the routine measurement of pH in
D5128 Test Method for On-Line pH Measurement of Water
water and is especially useful for continuous monitoring. Two
of Low Conductivity
buffers are used to standardize the instrument under controlled
D5464 Test Method for pH Measurement of Water of Low
parameters, but the conditions are somewhat less restrictive
Conductivity
thanthoseinTestMethodA.Foron-linemeasurement,alsosee
D6569 Test Method for On-Line Measurement of pH
Test Method D6569 which provides more detail.
E70 Test Method for pH of Aqueous Solutions With the
1.4 Both test methods are based on the pH scale established
Glass Electrode
2
by NIST (formerly NBS) Standard Reference Materials.
3. Terminology
1.5 Neither test method is considered to be adequate for
measurement of pH in water whose conductivity is less than
3.1 Definitions—For definitions of terms used in these test
about 5 µS/cm. Refer to Test Methods D5128 and D5464.
methods, refer to Terminology D1129.
1.6 Precision and bias data were obtained using buffer 3.2 Definitions of Terms Specific to This Standard:
3.2.1 pH, n—the negative logarithm of the hydrogen ion
solutions only. It is the user’s responsibility to assure the
activity in an aqueous solution or the logarithm of the
validity of these test methods for untested types of water.
reciprocal of the hydrogen ion activity.
1.7 The values stated in SI units are to be regarded as
3.2.1.1 Discussion—the pH of an aqueous solution is de-
standard. No other units of measurement are included in this
rived from E, the electromotive force (emf) of the cell
standard.
glass electrode | solution || reference electrode
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
(where the double vertical line represents a liquid junc-
responsibility of the user of this standard to establish appro-
tion) when the electrodes are immersed in the solution in the
priate safety and health practices and determine the applica-
diagrammed position, and E is the electromotive force ob-
s
bility of regulatory limitations prior to use.
tained when the electrodes are immersed in a reference buf-
fer solution.
With the assigned pH of the reference buffer designated as
1
These test methods are under the jurisdiction of ASTM Committee D19 on
Water and are the direct responsibility of Subcommittee D19.03 on Sampling Water
and Water-Formed Deposits, Analysis of Water for Power Generation and Process
3
Use, On-Line Water Analysis, and Surveillance of Water. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2012. Published January 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1953. Last previous edition approved in 2005 as D1293 – 99(2005). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D1293-11. the ASTM website.
2 4
“Standard Reference Materials: Standardization of pH Measurements” Wu and The last approved version of this historical standard is referenced on
Koch, NBS Special Publications No. 260-53, 1988. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D1293 − 12
TABLE 1 Slope Factor at Various Te
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This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D1293–99 (Reapproved 2005) Designation:D1293–12
Standard Test Methods for
1
pH of Water
This standard is issued under the fixed designation D1293; 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 Department of Defense.
1. Scope
1.1 ThesetestmethodscoverthedeterminationofpHbyelectrometricmeasurementusingtheglasselectrodeasthesensor.Two
test methods are given as follows:
Sections
Test Method A—Precise Laboratory Measurement 8 to 15
Test Method B—Routine or Continuous Measurement 16 to 24
1.2 Test Method A covers the precise measurement of pH in water utilizing at least two of seven standard reference buffer
solutions for instrument standardization.
1.3 Test Method B covers the routine measurement of pH in water and is especially useful for continuous monitoring. Two
buffers are used to standardize the instrument under controlled parameters, but the conditions are somewhat less restrictive than
those in Test Method A. For on-line measurement, also see Test Method D6569 which provides more detail.
2
1.4 Both test methods are based on the pH scale established by NIST (formerly NBS) Standard Reference Materials.
1.5 Neither test method is considered to be adequate for measurement of pH in water whose conductivity is less than about 5
µS/cm. Refer to Test Methods D5128 and D5464.
1.6 Precisionandbiasdatawereobtainedusingbuffersolutionsonly.Itistheuser’sresponsibilitytoassurethevalidityofthese
test methods for untested types of water.
1.7
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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.
2. Referenced Documents
3
2.1 ASTM Standards:
D1066 Practice for Sampling Steam
D1067 Test Methods for Acidity or Alkalinity of Water
4
D1129 Terminology Relating to Water D1192
D1192 Guide for Equipment for Sampling Water and Steam in Closed Conduits
D1193 Specification for Reagent Water
D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
D3370 Practices for Sampling Water from Closed Conduits
D5128 Test Method for On-Line pH Measurement of Water of Low Conductivity
D5464 Test Method for pH Measurement of Water of Low Conductivity
D6569 Test Method for On-Line Measurement of pH
E70 Test Method for pH of Aqueous Solutions With the Glass Electrode
1
These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.03 on Sampling of Water and
Water-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water.
CurrenteditionapprovedJan.1,2005.2012.PublishedJanuary2005.2012.Originallyapprovedin1953.Lastpreviouseditionapprovedin19992005asD1293–99(2005).
DOI: 10.1520/D1293-99R05.10.1520/D1293-11.
2
“Standard Reference Materials: Standardization of pH Measurements” Wu and Koch, NBS Special Publications No. 260-53, 1988.
3
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
4
Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
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D1293–12
3. Terminology
3.1 Definitions—For definitions of terms used in these test methods, refer to Terminology D1129.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 pH, n—the negative logarithm of the hydrogen ion activity in an aqueous solution or the logarithm of the reciprocal of
the hydrogen ion activity.
3.2.1.1 Discussion—the pH of an aqueous solution is derived from E, the electromotive force (emf) of the cell
glass electrode | solution || reference electrode
(where the double vertical line represents a liquid junction) when the electrodes are immersed in the solution in the diagrammed
position, and
...
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