ASTM D1172-15(2024)

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, health, and environmental 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.  
1.4 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

• Status: Published
• Publication Date: 31-Dec-2023
• ICS: 71.100.40 - Surface active agents
• Technical Committee: D12 - Soaps and Other Detergents
• Drafting Committee: D12.15 - Physical Testing

Relations

• Replaces: ASTM D1172-15 - Standard Guide for pH of Aqueous Solutions of Soaps and Detergents
• Effective Date: 01-Jan-2024
• Refers: ASTM E70-24 - Standard Test Method for pH of Aqueous Solutions With the Glass Electrode
• Effective Date: 01-Jan-2024
• Refers: ASTM E70-19 - Standard Test Method for pH of Aqueous Solutions With the Glass Electrode
• Effective Date: 01-Nov-2019
• Referred By: ASTM D1570-95(2023) - Standard Test Methods for Sampling and Chemical Analysis of Fatty Alkyl Sulfates
• Effective Date: 01-Jan-2024
• Referred By: ASTM D4252-89(2017) - Standard Test Methods for Chemical Analysis of Alcohol Ethoxylates and Alkylphenol Ethoxylates
• Effective Date: 01-Jan-2024
• Referred By: ASTM D3673-89(2016) - Standard Test Methods for Chemical Analysis of Alpha Olefin Sulfonates
• Effective Date: 01-Jan-2024
• Referred By: ASTM D8179-18 - Standard Guide for Characterizing Detergents for the Cleaning of Clinically-used Medical Devices
• Effective Date: 01-Jan-2024

Overview

ASTM D1172-15(2024) - Standard Guide for pH of Aqueous Solutions of Soaps and Detergents provides comprehensive guidance for preparing aqueous solutions of soaps and detergents and accurately determining their pH. Developed and approved by ASTM International, this standard details essential procedures and recommended equipment to ensure reliable and consistent pH measurements in laboratory and industrial environments. By following this guide, organizations can maintain quality control and regulatory compliance in the production and analysis of cleaning products.

Key Topics

• Preparation of Aqueous Solutions:
  The guide outlines clear procedures for dissolving both synthetic detergents and soaps in distilled water or its equivalent, ensuring representative and reproducible samples for pH testing.

• pH Measurement Techniques:
  Standardized methods are specified for calibrating pH meters and selecting suitable electrodes, such as the Fisher accupHast Variable Temperature pH Combination Electrode or the Orion Ross Sure Flow electrode, ensuring high accuracy.

• Sampling Methods:
  The standard references established ASTM methods for sampling soaps and detergents, promoting consistency in laboratory practices.

• Safety and Compliance:
  Users are reminded to observe safety, health, and environmental precautions, including reviewing Material Safety Data Sheets (MSDS) for all reagents.

• SI Units:
  All measurements and values in the standard are expressed in SI units to ensure global clarity and uniformity.

Applications

ASTM D1172-15(2024) is crucial for a wide range of applications across industries such as:

• Manufacturing Quality Control:
  Producers of soaps and detergents rely on this standard to monitor and control the pH of their products, which affects cleaning efficacy, stability, and consumer safety.

• Product Formulation:
  Chemists and formulating teams use standardized pH determination methods to develop new detergent and soap formulations that meet performance, regulatory, and user safety requirements.

• Laboratory Analysis:
  Analytical laboratories reference this guide for precise and consistent pH measurement of aqueous solutions, supporting product compliance and research.

• Regulatory Compliance:
  Compliance with ASTM D1172-15(2024) demonstrates adherence to international standards, relevant quality systems, and export/import regulations for cleaning products.

• Research & Development:
  R&D departments apply these procedures when comparing new ingredients, innovating product performance, or addressing customer requirements.

Related Standards

For organizations implementing or auditing pH measurement protocols, the following standards provide additional or complementary guidance:

• ASTM E70: Test Method for pH of Aqueous Solutions with the Glass Electrode – foundational reference for pH electrode performance and calibration.
• ASTM D501: Test Methods of Sampling and Chemical Analysis of Alkaline Detergents.
• Withdrawn ASTM D460: Previously addressed sampling and chemical analysis of soaps and soap products.
• World Trade Organization TBT Committee Guidelines:
  This standard aligns with internationally recognized principles on standardization, ensuring global acceptance and interoperability.

Keywords: pH measurement, aqueous solutions, soaps, detergents, ASTM D1172-15(2024), quality control, laboratory testing, product formulation, standard methods, cleaning products, regulatory compliance, international standard.

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 (Reapproved 2024)
Standard Guide for
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 4. Reagent
1.1 This guide covers the preparation of aqueous solutions 4.1 Distilled Water or Equivalent—Distilled water or
of soaps and detergents and the determination of their pH.
equivalent shall be boiled thoroughly, or purged with CO -free
air, to remove CO and shall be protected with soda-lime while
1.2 The values stated in SI units are to be regarded as 2
cooling and in storage. The pH of this water shall be between
standard. No other units of measurement are included in this
6.2 and 7.2 at 25 °C. The residue on evaporation, when heated
standard.
at 105 °C for 1 h, shall not be more than 0.5 mg/L.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Procedure for Synthetic Detergents
responsibility of the user of this standard to establish appro-
5.1 Preparation of Solutions—Weigh 1 g 6 0.001 g of the
priate safety, health, and environmental practices and deter-
sample (see Note 1 and Note 2) and transfer to a 1 L volumetric
mine the applicability of regulatory limitations prior to
flask. Partially fill the flask with distilled water or equivalent
use. Material Safety Data Sheets are available for reagents and
and agitate until the sample is completely dissolved. Make
materials. Review them for hazards prior to usage.
certain the solute is completely dissolved and allow time for
1.4 This international standard was developed in accor-
the evolution of dissolved gases. Fill to the calibration mark
dance with internationally recognized principles on standard-
with distilled water or equivalent. Stopper the flask; mix
ization established in the Decision on Principles for the
thoroughly. The desirable condition requires the solution to
Development of International Standards, Guides and Recom-
come to equilibrium. Allow the solution to equilibrate at 25 °C
mendations issued by the World Trade Organization Technical
6 2.0 °C. The use of a temperature compensation probe may
Barriers to Trade (TBT) Committee.
allow alternate temperatures. Records should show the time
2. Referenced Documents
interval between solution preparation and pH measurement.
2.1 ASTM Standards:
NOTE 1—The procedure for detergents other than soaps is applicable to
D460 Test Methods for Sampling and Chemical Analysis of
some compositions that contain minor proportions of soap, provided that
the solutions do not show evidence of gelling prior to carrying out the pH
Soaps and Soap Products (Withdrawn 2023)
measurement.
D501 Test Methods of Sampling and Chemical Analysis of
NOTE 2—Measurements of pH of gelled solutions lack constancy and
Alkaline Detergents
reproducibility. The procedure for soaps (Section 6) is designed to produce
E70 Test Method for pH of Aqueous Solutions With the
solutions that will not gel before the pH measurement is carried out. This
Glass Electrode procedure should be used for all detergent solutions, soap or nonsoap, that
give evidence of gelling or incomplete solution when prepared in
3. Sampling
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
3.1 The material shall be sampled in accordance with Test
used in dissolving the sample, or that are intended exclusiv
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