ASTM D3049-89(2009)
(Test Method)Standard Test Method for Synthetic Anionic Ingredient by Cationic Titration
Standard Test Method for Synthetic Anionic Ingredient by Cationic Titration
SIGNIFICANCE AND USE
This test method offers a means of determining anionic detergents commonly found in laundry, dishwashing, and other cleaning materials. Accurate determination of the anionic active substance is highly important in assessing the cost and effectiveness of such cleaning substances.
This test method is not affected by low molecular weight sulfonates, such as those of toluene and xylene commonly found in detergent formulations, when these substances are present up to 15 weight % of active material.
SCOPE
1.1 This test method covers the determination of the amount of synthetic anionic ingredient in a surfactant by direct titration with a standardized cationic reagent. The test method is a simple and convenient means for the quantitative estimation of the anionic material. The end point is detected by the transfer of a colored complex from an organic solvent phase to an aqueous phase. The colored complex is formed by the addition of a solution of dye to a solution of the anionic surfactant. This complex is soluble in the organic-solvent phase and insoluble in the aqueous phase. When this solution is titrated with a standardized solution of a cationic reagent, the dye is displaced from the colored complex and, being water-soluble, migrates to the aqueous phase. Therefore, a cationic titrating solution that has been standardized against a characterized anionic agent can be used to analyze for other anionics of known molecular mass.
1.2 This test method is applicable to alkylaryl sulfonates, alkyl sulfonates, alkyl sulfates and hydroxy-sulfates, alkylphenol- and fatty alcohol ethoxy-sulfates and dialkylsulfosuccinates. It applies to active materials containing one hydrophilic group per molecule.
General Information
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Standards Content (Sample)
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Designation: D3049 − 89(Reapproved 2009)
Standard Test Method for
Synthetic Anionic Ingredient by Cationic Titration
This standard is issued under the fixed designation D3049; 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.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 Thistestmethodcoversthedeterminationoftheamount
bility of regulatory limitations prior to use. A precautionary
ofsyntheticanionicingredientinasurfactantbydirecttitration
statementappearsinSection7.MaterialSafetyDataSheetsare
with a standardized cationic reagent. The test method is a
available for reagents and materials. Review them for hazards
simple and convenient means for the quantitative estimation of
prior to usage.
the anionic material. The end point is detected by the transfer
of a colored complex from an organic solvent phase to an
2. Referenced Documents
aqueous phase. The colored complex is formed by the addition
2.1 ASTM Standards:
of a solution of dye to a solution of the anionic surfactant.This
complex is soluble in the organic-solvent phase and insoluble D1193 Specification for Reagent Water
in the aqueous phase. When this solution is titrated with a
3. Summary of Test Method
standardized solution of a cationic reagent, the dye is displaced
fromthecoloredcomplexand,beingwater-soluble,migratesto
3.1 An aqueous solution of an anionic-type detergent, to
the aqueous phase. Therefore, a cationic titrating solution that
which is added a small amount of mixed indicator (dimidium
hasbeenstandardizedagainstacharacterizedanionicagentcan
bromideanddisulphineblue),isshakenwithaqueousHyamine
beusedtoanalyzeforotheranionicsofknownmolecularmass.
solutionandchloroform.Thepinkcomplexwhichisformedby
thereactionbetweentheanionicdetergentandthecationicdye,
1.2 This test method is applicable to alkylaryl sulfonates,
dimidium bromide, is extracted into the chloroform. Incre-
alkyl sulfonates, alkyl sulfates and hydroxy-sulfates,
ments of additional Hyamine solution are added with a
alkylphenol- and fatty alcohol ethoxy-sulfates and dialkylsul-
thorough mixing after each addition.At first the reaction takes
fosuccinates. It applies to active materials containing one
place between the Hyamine and the excess anionic-type
hydrophilic group per molecule.
detergent, during which there is no noticeable change in the
1.3 The analytical procedures appear in the following order:
color (pink) of the chloroform phase.As the equivalence point
Sections
between the anionic and cationic materials is approached, the
Reagents 6
dimidium bromide portion of the anionic detergent active-
Primary Standard 8
Purity 8.2
dimidium bromide complex (pink) is gradually released and
Alcohols 8.3
transferred to the aqueous layer.As excess Hyamine is added it
Free Acid or Alkali 8.4
reacts with the anionic dye, disulphine blue, to form a
Preparation of Mixed Indicator Solution 9
Preparation of Hyamine Solution 10
chloroform-soluble blue complex. During the transition at the
Standardization of Hyamine Solution 11
end point the chloroform layer, therefore, changes from pink to
General Procedure for Anionic-Active Material 12
gray, to blue. The gray color is taken as the end point.
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Significance and Use
standard.The values stated in SI units are to be regarded as
4.1 This test method offers a means of determining anionic
standard. No other units of measurement are included in this
detergents commonly found in laundry, dishwashing, and other
standard.
cleaning materials. Accurate determination of the anionic
1.5 This standard does not purport to address all of the
active substance is highly important in assessing the cost and
safety concerns, if any, associated with its use. It is the
effectiveness of such cleaning substances.
This test method is under the jurisdiction of ASTM Committee D12 on Soaps
and Other Detergents and is the direct responsibility of Subcommittee D12.12 on
Analysis and Specifications of Soaps, Synthetics, Detergents and their Components. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2009. Published March 2010. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1972 as D3049– 72 T. Last previous edition approved in 2003 as Standards volume information, refer to the standard’s Document Summary page on
D3049–89(2003). DOI: 10.1520/D3049-89R09. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3049 − 89 (2009)
4.2 Thistestmethodisnotaffectedbylowmolecularweight Molarity 5 W 3 P / 288.4 3100 (1)
~ ! ~ !
sulfonates, such as those of toluene and xylene commonly
where:
found in detergent formulations, when these substances are
W = sodium lauryl sulfate, g, and
present up to 15 weight % of active material.
P = purity of the sodium lauryl sulfate, %.
5. Interferences
6.11 Sodium Sulfate (Na SO ), anhydrous.
2 4
5.1 Normal inorganic components of detergent
6.12 Sulfuric Acid, Standard (0.1 N)—Prepare a 0.1 N
formulations, such as chloride, sulfate, borate, phosphates,
solution of sulfuric acid (H SO ).
2 4
perborate, and silicates do not interfere. Soaps, urea, and
6.13 Sulfuric Acid, Standard (0.5 N)—Prepare a 0.5 N
ethylenediaminetetraacetic acid salts do not interfere. Bleach-
solution of H SO .
2 4
ing agents other than perborate should be destroyed prior to
6.14 Sulfuric Acid, Standard (1 N)—Prepare a 1 N solution
performing this analysis. Low molecular weight sulfonates,
of H SO .
such as those of toluene and xylene, do not interfere when
2 4
present up to 15 % (w) of active material. Since the titration is
7. Safety Precaution
performed under acidic conditions (about pH 2.0), care should
7.1 This test method includes the use of small amounts of
be exercised when using this procedure on products containing
significant amounts of alkaline materials, such as carbonates chloroform. Appropriate safety practices, such as those in-
cluded in the Material Safety Data Sheets for chloroform,
and silicates, to ensure that the final solution is being titrated in
the proper pH range. should be employed. Good ventilation is especially important.
6. Reagents 8. Primary Standard
8.1 The primary standard used in this procedure is sodium
6.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that laurylsulfate. Threetestsaremadeonthisprimarystandardas
follows:
all reagents shall conform to the specifications of the Commit-
tee onAnalytical Reagents of theAmerican Chemical Society,
8.2 Purity:
where such specifications are available. Other grades may be
8.2.1 This test should be run in duplicate.
used, provided it is first ascertained that the reagent is of
8.2.2 Weigh, to the nearest 0.1 mg, 10 6 0.2 g of the
sufficiently high purity to permit its use without lessening the
primary standard into a 250-mL round-bottom flask.
accuracy of the determination.
8.2.3 Addexactly25mLof0.5 NH SO .Itisnotnecessary
2 4
to standardize this acid.
6.2 Purity of Water—Unless otherwise indicated, references
8.2.4 Reflux under a water condenser for 2 h. Heat moder-
towatershallbeunderstoodtomeanreagentwaterconforming
ately in the beginning until the solution clarifies and the
to Specification D1193.
foaming ceases; then increase the heat input until a vigorous
6.3 Chloroform.
reflux is attained.
6.4 Ethanol.
8.2.5 Remove the heat source, cool the flask, and then wash
down the condenser with approximately 30 mL of ethanol
6.5 Petroleum Ether, boiling range 30 to 50°C.
followed by 50 mL of water.Add the washings to the reaction
6.6 Phenolphthalein Indicator Solution (1 %)—Dissolve1g
flask.
of phenolphthalein in 95 % ethanol and dilute to 100 mL.
8.2.6 Disconnect the condenser and wash the point and the
6.7 Sodium Hydroxide, Standard Solution (0.1 N)—Prepare
neck with water. Add these washings to the reaction flask.
a 0.1 N solution of sodium hydroxide (NaOH).
8.2.7 Add a few drops of 1 % phenolphthalein indicator
solution and titrate the H SO with standardized 1 N NaOH
6.8 Sodium Hydroxide, Standard Solution (1 N)—Prepare a
2 4
solution.
1 N solution of NaOH.
8.2.8 Determine a blank value by titrating 25 mL of the 0.5
6.9 Sodium Hydroxide, Standard Solution (50 %)—Prepare
N H SO with the standardized 1 N NaOH solution. This
2 4
a 50 % solution of NaOH.
should be done in duplicate and the average used.
6.10 Sodium Lauryl Sulfate, Standard Solution, (0.004 M).
8.2.9 Calculate the percent purity of the primary standard as
6.10.1 Weigh accurately between 1.14 and 1.16 g of sodium
follows:
lauryl sulfate and dissolve in 200 mL of water.
Purity,% 5 @28.84 3 ~A 2 B! 3 N#/W (2)
6.10.2 Transfertoastopperedgraduated1-Lflaskanddilute
to volume with water. where:
6.10.3 Calculate the molarity of the solution as follows:
A = NaOH solution used in sample titration, mL,
B = NaOH solution used in blank titration, mL,
N = normality of the NaOH solution, and
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia Manufactured by British Drug House, Ltd. as Product No. 30176. It is sold as
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, being more than 99 % pure. It is available in the United States from Gallard-
MD. Schlesinger Chemical Manufacturing Corp., Carle Place, Long Island, NY 11514.
D3049 − 89 (2009)
9. Preparation of the Mixed Indicator Solution
W = primary standard used, g.
9.1 Disulphine Blue.
8.2.10 For best precision and accuracy, temperature and
buret corrections should be made when titrating the hydroly- 9.2 Dimidium Bromide.
sate of the sodium lauryl sulfate with 1 N NaOH solution.
9.3 Mixed Indicator Stock Solution—Weigh 0.5 6 0.005 g
of dimidium bromide into a 50 mL-beaker. Weigh 0.25 6
8.3 Alcohols:
0.005 g of disulphine blue into a second 50-mLbeaker.Add 25
8.3.1 The primary standard, sodium lauryl sulfate, is sold as
to 30 mL of 1+10 (v/v) hot ethanol-water solution to each
having not more than 1 weight % (Note 1) of a sum of decyl
beaker. Stir each until the dye is dissolved; then add both
and tetradecyl a
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