ASTM D1172-15

Standard Guide for pH of Aqueous Solutions of Soaps and Detergents

ABSTRACT
This guide details the standard procedures for the preparation of aqueous solutions of soaps and detergents and the determination of their pH. The required reagent for this procedure is distilled water or its equivalent, and the recommended electrodes for the determination of pH are the Fischer Accuphast combination electrode or Orion Ross Sure Flow electrode or their equivalents.
SCOPE
1.1 This guide covers the preparation of aqueous solutions of soaps and detergents and the determination of their pH.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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. Material Safety Data Sheets are available for reagents and materials. Review them for hazards prior to usage.

General Information

• Status: Historical
• Publication Date: 30-Apr-2015
• ICS: 71.100.40 - Surface active agents
• Technical Committee: D12 - Soaps and Other Detergents
• Drafting Committee: D12.15 - Physical Testing

Relations

• Replaces: ASTM D1172-95(2007) - Standard Guide for pH of Aqueous Solutions of Soaps and Detergents
• Effective Date: 01-May-2015
• Refers: ASTM E70-07(2015) - Standard Test Method for pH of Aqueous Solutions With the Glass Electrode
• Effective Date: 01-Jun-2015
• Refers: ASTM D501-03(2009) - Standard Test Methods of Sampling and Chemical Analysis of Alkaline Detergents
• Effective Date: 01-Oct-2009
• Refers: ASTM D460-91(2005) - Standard Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products
• Effective Date: 01-May-2005
• Refers: ASTM D501-03 - Standard Test Methods of Sampling and Chemical Analysis of Alkaline Detergents
• Effective Date: 01-Oct-2003
• Refers: ASTM D460-91(1997) - Standard Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products
• Effective Date: 10-Mar-1997
• Referred By: ASTM D4252-89(2017) - Standard Test Methods for Chemical Analysis of Alcohol Ethoxylates and Alkylphenol Ethoxylates
• Effective Date: 01-May-2015
• Referred By: ASTM D8179-18 - Standard Guide for Characterizing Detergents for the Cleaning of Clinically-used Medical Devices
• Effective Date: 01-May-2015
• Referred By: ASTM D1570-95(2023) - Standard Test Methods for Sampling and Chemical Analysis of Fatty Alkyl Sulfates
• Effective Date: 01-May-2015
• Referred By: ASTM D3673-89(2016) - Standard Test Methods for Chemical Analysis of Alpha Olefin Sulfonates
• Effective Date: 01-May-2015

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.
Designation: D1172 − 15
Standard Guide for
1
pH of Aqueous Solutions of Soaps and Detergents
This standard is issued under the fixed designation D1172; 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 6.2 and 7.2 at 25°C. The residue on evaporation, when heated
at 105°C for 1 h, shall not be more than 0.5 mg/L.
1.1 This guide covers the preparation of aqueous solutions
of soaps and detergents and the determination of their pH.
5. Procedure for Synthetic Detergents
1.2 The values stated in SI units are to be regarded as
5.1 Preparation of Solutions—Weigh 1 6 0.001 g of the
standard. No other units of measurement are included in this
sample (see Note 1 and Note 2) and transfer to a 1-L
standard.
volumetric flask. Partially fill the flask with distilled water or
1.3 This standard does not purport to address all of the
equivalent and agitate until the sample is completely dissolved.
safety concerns, if any, associated with its use. It is the
Make certain the solute is completely dissolved and allow time
responsibility of the user of this standard to establish appro-
fortheevolutionofdissolvedgases.Filltothecalibrationmark
priate safety and health practices and determine the applica-
with distilled water or equivalent. Stopper the flask; mix
bility of regulatory limitations prior to use. Material Safety
thoroughly. The desirable condition requires the solution to
Data Sheets are available for reagents and materials. Review
come to equilibrium.Allow the solution to equilibrate at 25 6
them for hazards prior to usage.
2.0°C. The use of a temperature compensation probe may
allow alternate temperatures. Records should show the time
2. Referenced Documents
interval between solution preparation and pH measurement.
2
2.1 ASTM Standards:
D460 Test Methods for Sampling and Chemical Analysis of NOTE 1—The procedure for detergents other than soaps is applicable to
some compositions that contain minor proportions of soap, provided that
Soaps and Soap Products
the solutions do not show evidence of gelling prior to carrying out the pH
D501 Test Methods of Sampling and Chemical Analysis of
measurement.
Alkaline Detergents
NOTE 2—Measurements of pH of gelled solutions lack constancy and
E70 Test Method for pH of Aqueous Solutions With the
reproducibility.Theprocedureforsoaps(Section6)isdesignedtoproduce
Glass Electrode
solutions that will not gel before the pH measurement is carried out. This
procedure should be used for all detergent solutions, soap or nonsoap, that
give evidence of gelling or incomplete solution when prepared in
3. Sampling
accordancewith5.1.Theprocedureforsoapsisnotapplicabletodetergent
3.1 The material shall be sampled in accordance with Test
compositions that are known to be chemically altered by the boiling water
Methods D460 or D501, whichever is applicable.
used in dissolving the sample, or that are intended exclusively for use in
cold water.
4. Reagent
5.2 Determination of pH—Calibrate the pH meter and
4.1 Distilled Water or Equivalent—Distilled water or
suitable electrodes. The recommended electrodes are Fisher
equivalent shall be boiled thoroughly, or purged with CO -free
2 Scientific accupHast Variable Temperature pH Combination
air, to remove CO and shall be protected with soda-lime while
Electrodes or Orion Ross Sure Flow electrode or equivalent
2
cooling and in storage. The pH of this water shall be between
electrodes. Measure the pH of the solution while stirring.
6. Procedure for Soaps (use for soaps and detergents that
1
This guide is under the jurisdiction of ASTM Committee D12 on Soaps and
tend to gel when added to water at room temperature)
Other Detergents and is the direct responsibility of Subcommittee D12.15 on
Physical Testing.
6.1 Preparation of Apparatus—Use a pH meter and elec-
CurrenteditionapprovedMay1,2015.PublishedJuly2015.Originallyapproved
trodes as defined in Test Method E70. Set the temperature
in 1951. Last previous edition approved in 2007 as D1172 – 95(2007). DOI:
10.1520/D1172-15.
control knob at 40°C and standardize the assembly with a
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
suitable buffer solution in the pH 9 to 11 range at 40°C. Leave
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
the electrode in the buffer to maintain temperature equilibrium.
Standards v
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: D1172 − 95 (Reapproved 2007) D1172 − 15
Standard Guide for
1
pH of Aqueous Solutions of Soaps and Detergents
This standard is issued under the fixed designation D1172; 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
1.1 This guide covers the preparation of aqueous solutions of soaps and detergents and the determination of their pH.
1.2 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
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. Material Safety Data Sheets are available for reagents and materials. Review them for hazards prior to
usage.
2. Referenced Documents
2
2.1 ASTM Standards:
D460 Test Methods for Sampling and Chemical Analysis of Soaps and Soap Products
D501 Test Methods of Sampling and Chemical Analysis of Alkaline Detergents
E70 Test Method for pH of Aqueous Solutions With the Glass Electrode
3. Sampling
3.1 The material shall be sampled in accordance with Test Methods D460 or D501, whichever is applicable.
4. Reagent
4.1 Distilled Water or Equivalent—Distilled water or equivalent shall be boiled thoroughly, or purged with CO -free air, to
2
remove CO and shall be protected with soda-lime or soda-asbestos (Ascarite) while cooling and in storage. The pH of this water
2
shall be between 6.2 and 7.2 at 25°C. The residue on evaporation, when heated at 105°C for 1 h, shall not be more than 0.5 mg/L.
5. Procedure for Synthetic Detergents
5.1 Preparation of Solutions—Weigh 1 6 0.001 g of the sample (see Note 1 and Note 2) and transfer to a 1-L volumetric flask.
Partially fill the flask with distilled water or equivalent and agitate until the sample is completely dissolved. Make certain the solute
is completely dissolved and allow time for the evolution of dissolved gases. Fill to the calibration mark with distilled water or
equivalent. Stopper the flask; mix thoroughly. The desirable condition requires the solution to come to equilibrium. Allow the
solution to equilibrate at 25 6 2.0°C. The use of a temperature compensation probe may allow alternate temperatures. Records
should show the time interval between solution preparation and pH measurement.
NOTE 1—The procedure for detergents other than soaps is applicable to some compositions that contain minor proportions of soap, provided that the
solutions do not show evidence of gelling prior to carrying out the pH measurement.
NOTE 2—Measurements of pH of gelled solutions lack constancy and reproducibility. The procedure for soaps (Section 6) is designed to produce
solutions that will not gel before the pH measurement is carried out. This procedure should be used for all detergent solutions, soap or nonsoap, that give
evidence of gelling or incomplete solution when prepared in accordance with 5.1. The procedure for soaps is not applicable to detergent compositions
that are known to be chemically altered by the boiling water used in dissolving the sample, or that are intended exclusively for use in cold water.
1
This guide is under the jurisdiction of ASTM Committee D12 on Soaps and Other Detergents and is the direct responsibility of Subcommittee D12.15 on Physical Testing.
Current edition approved Oct. 1, 2007May 1, 2015. Published October 2007July 2015. Originally approved in 1951. Last previous edition approved in 20012007 as
D1172 – 95(2001).(2007). DOI: 10.1520/D1172-95R07.10.1520/D1172-15.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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D1172 − 15
5.2 Determination of pH—Calibrate the pH meter and suitable electrodes. The recommended electrodes are Fischer Accuphast
combination electrode
...