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 the 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-Sep-2007
Drafting Committee
Current Stage
Ref Project

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ASTM D1172-95(2007) - Standard Guide for pH of Aqueous Solutions of Soaps and Detergents
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D1172 − 95(Reapproved 2007)
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 Department of Defense.
1. Scope of this water 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
1.1 This guide covers the preparation of aqueous solutions
more than 0.5 mg/L.
of soaps and detergents and the determination of their pH.
1.2 The values stated in SI units are to be regarded as the
5. Procedure for Synthetic Detergents
standard.
5.1 Preparation of Solutions—Weigh 1 6 0.001 g of the
1.3 This standard does not purport to address all of the
sample (see Note 1 and Note 2) and transfer to a 1-L
safety concerns, if any, associated with its use. It is the
volumetric flask. Partially fill the flask with distilled water or
responsibility of the user of this standard to establish appro-
equivalent and agitate until the sample is completely dissolved.
priate safety and health practices and determine the applica-
Make certain the solute is completely dissolved and allow time
bility of regulatory limitations prior to use. Material Safety
fortheevolutionofdissolvedgases.Filltothecalibrationmark
Data Sheets are available for reagents and materials. Review
with distilled water or equivalent. Stopper the flask; mix
them for hazards prior to usage.
thoroughly. The desirable condition requires the solution to
come to equilibrium.Allow the solution to equilibrate at 25 6
2. Referenced Documents
2.0°C. The use of a temperature compensation probe may
2.1 ASTM Standards:
allow alternate temperatures. Records should show the time
D460 Test Methods for Sampling and Chemical Analysis of
interval between solution preparation and pH measurement.
Soaps and Soap Products
NOTE 1—The procedure for detergents other than soaps is applicable to
D501 Test Methods of Sampling and Chemical Analysis of
some compositions that contain minor proportions of soap, provided that
Alkaline Detergents
the solutions do not show evidence of gelling prior to carrying out the pH
E70 Test Method for pH of Aqueous Solutions With the
measurement.
Glass Electrode
NOTE 2—Measurements of pH of gelled solutions lack constancy and
reproducibility.Theprocedureforsoaps(Section6)isdesignedtoproduce
3. Sampling 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
3.1 The material shall be sampled in accordance with Test
give evidence of gelling or incomplete solution when prepared in
Methods D460 or D501, whichever is applicable.
accordancewith5.1.Theprocedureforsoapsisnotapplicabletodetergent
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
4. Reagent
cold water.
4.1 Distilled Water or Equivalent—Distilled water or
5.2 Determination of pH—Calibrate the pH meter and
equivalent shall be boiled thoroughly, or purged with CO -free
suitable electrodes. The recommended electrodes are Fischer
air, to remove CO and shall be protected with
...

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