ASTM D6173-97(2014)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6173 − 97 (Reapproved 2014)
Standard Test Method for
Determination of Various Anionic Surfactant Actives by
Potentiometric Titration
This standard is issued under the fixed designation D6173; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 Thistestmethodisbasedonapotentiometrictitrationof 3.1 Definitions of Terms Specific to This Standard:
common anionic surfactants and blends of anionic surfactant 3.1.1 active matter, n—the organic surface-active material
with a hydrotrope. This test method solely is intended for the present in the detergent.Also defined in Terminology D459 as
analysis of active matter in the following surfactants: alcohol active ingredient of detergents.
ether sulfate, alpha olefin sulfonate, alkylbenzene sulfonic
acid, alcohol sulfate, sodium alkylbenzene sulfonate/sodium 4. Summary of Test Method
xylene sulfonate blend (5:1), sodium alkylbenzene sulfonate/
4.1 This test method describes a potentiometric titration
sodium xylene sulfonate blend (16:1), and sodium alkylben-
procedure for determining active matter in anionic surfactant.
zenesulfonate/sodiumxylenesulfonateblend(22:1).Ithasnot
Theanionicsurfactantisfirstdissolvedinwater,andthepHof
been tested for surfactant formulations.
the solution is adjusted according to the type of anionic
1.2 The values stated in SI units are to be regarded as surfactant being measured. In the potentiometric titration the
standard. No other units of measurement are included in this anionic surfactant is titrated with a standard solution of
standard. Hyamineusingasurfactantelectrode,andthereactioninvolves
the formation of a complex between the anionic surfactant and
1.3 This standard does not purport to address all the safety
the cationic titrant (Hyamine), which then precipitates. At the
concerns, if any, associated with its use. It is the responsibility
end point the surfactant electrode appears to respond to an
of the user of this standard to establish appropriate safety and
excess of titrant with potential change large enough to give a
health practices and determine the applicability of regulatory
well defined inflection in the titration curve.
limitations prior to use. Material Safety Data Sheets are
available for reagents and materials. Review them for hazards
5. Significance and Use
prior to usage.
5.1 The most common anionic surfactants presented in this
2. Referenced Documents
test method are used widely in synthetic detergents and other
2.1 ASTM Standards:
household cleaners. Current analysis of the active matter in
D459Terminology Relating to Soaps and Other Detergents these anionic surfactants involves the two-phase aqueous/
D1681Test Method for SyntheticAnionicActive Ingredient
chloroform titration with a mixed indicator, organic dyes such
in Detergents by Cationic Titration Procedure as disulphine blue/dimidium bromide (see Test Method
D3049Test Method for Synthetic Anionic Ingredient by
D3049), and methylene blue (see Test Method D1681). This
Cationic Titration test method eliminates the use of hazardous chloroform, the
use of which is restricted for environmental and toxicological
reasons.
This test method is under the jurisdiction ofASTM Committee D12 on Soaps
and Other Detergents and is the direct responsibility of Subcommittee D12.12 on
5.2 This test method also describes the titration of various
AnalysisandSpecificationsofSoaps,Synthetics,DetergentsandtheirComponents.
ratio blends of sodium alkylbenzene sulfonate and sodium
Current edition approved Jan. 1, 2014. Published February 2014. Originally
xylene sulfonate. Active matter content in these blends is
approvedin1997.Lastpreviouseditionapprovedin2005asD6173-97(2005).DOI:
10.1520/D6173-97R14.
attributable directly to sodium alkylbenzene sulfonate.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Therefore, the presence of various amounts of sodium xylene
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
sulfonate in these blends does not interfere with the determi-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. nation of percent actives.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6173 − 97 (2014)
6. Apparatus 7.9 Sodium Lauryl Sulfate 0.0001 m Solution, buffered at
pH 4.00, with a graduated cylinder transfer 2 mL of sodium
6.1 Autotitration System, equipped with a delivery buret
3,4 laurylsulfate0.004Msolutiontoa150-mLbeaker.Add80mL
system, 10 or 20-mL capacity.
of deionized water and 1 mL of buffer solution pH 4.00 and
3,4
6.2 Phoenix Surfactant Combination Electrode, nitrate
mix well. This solution is use for conditioning the electrodes.
4,5
specific ion electrode, or surfactant electrode equipped with
7.10 Electrode Rinse Solution—Transfer approximately 50
silver/silver chloride reference electrode. The conditioning of
mLof0.1MHClsolutionto1Lvolumetricflaskanddiluteto
this type of electrode is essential for obtaining a good break in
volume.
the titration curve. Therefore, each electrode should be condi-
tioned in sodium lauryl sulfate 0.0001M solution for 15 min. 8. Preparation of Primary Standard Reagents
For other electrode requirements, follow the manufacturer’s -3
8.1 Sodium Lauryl Sulfate Solution, 4×10 N. Weigh
instruction manual.
accurately 1.15 + 0.01 g of sodium lauryl sulfate to the nearest
6.3 Analytical Balance. 0.1 mg. Dissolve in water and dilute to a final volume of 1L.
Calculate the normality of the solution according to the
6.4 Standard Laboratory Glassware.
following equation:
W 3P
7. Reagents
Normalityof SodiumLaurylSulfate 5 (1)
~288.38 3100!
7.1 Hyamine 1622, diisobutylphenoxyethoxyethyl dimethyl
benzyl ammonium chloride monohydrate. where:
P = purity of the sodium lauryl sulfate, weight %, and
7.2 Potassium Chloride, reagent grade.
W = weight of sodium lauryl sulfate, g.
4,7
7.3 Triton X-100 , electrophoresis grade.
8.2 Keep the solution no longer than one month before
7.4 Potassium Chloride 4.0 M Solution—Prepare by weigh-
making a fresh solution.
ingout30.00gtothenearest0.01gofpotassiumchlorideinto
-3
8.3 Hyamine 1622 Solution,4×10 N—Dissolve 1.85 +
a 100 mL volumetric glass and dissolving in deionized water.
0.5 g of Hyamine 1622 in deionized water and dilute to a final
Dilute to the mark with deionized water.Add exactly one drop
volume of 1L.
of Triton X-100 to the solution and mix well. This is only a
-3
8.4 Hyamine 1622 Solution Standardization, 4×10
reference electrode filling solution for the Phoenix electrode.
N—This determination shall be done in triplicate. Pipet 5.00
7.5 Triton X-100, 1 % Solution—Prepare by weighing 1.00
mL of the standard lauryl sulfate solution into a 150-mL
g of Triton X-100 into a 100-mLvolumetric flask and diluting
beaker.Add 50 mL of dionized water, and, while stirring, add
to the mark with deionized water.
1 mL of buffer solution pH 4 and 1 mL of Triton-X-100, 1%
4,8
7.6 Sodium Lauryl Sulfate , primary standard.
solution. To minimize noise in the titration, make sure that the
buret tip is placed close to the center of the stir bar. Stir
NOTE1—Sodiumlaurylsulfateshallbeanalyzedforpurityaccordingto
moderately. Erroneous results can occur if excessive foaming
the reagent section of Test Method D3049 before its use as primary
standard. takes place. Titrate potentiometrically with the Hyamine 1622
4,9 solution and record the titration volume. The Titroprocessor
7.7 Buffer Solution pH 4.00
will perform the titration, determine the inflection point and
4,9
7.8 Buffer Solution pH 7.00 —Pipet 10 mL of buffer
calculate the results according to the following equation:
solution pH 7.00 and transfer to a 100-mL volumetric flask.
N 35
Dilute to volume and mix well.
NormalityofHyamine1622 5 (2)
V
where:
N = normality of sodium lauryl sulfate standard solution,
The sole source of supply of the autotitration system and Phoenix electrode
known to the committee at this time is Brinkmann Instruments, Inc. Cantiague Rd.,
5 = sodium lauryl sulfate aliquot taken for titration, mL,
Westbury, NY 11590.
and
If you are aware of alternative suppliers, please provide this information to
V = Hyamine 1622 solution required to reach the endpoint,
ASTMheadquarters.Yourcommentswillreceivecarefulconsiderationatameeting
mL.
of the respons
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