ASTM D2959-95(2003)
(Test Method)Standard Test Method for Ethylene Oxide Content of Polyethoxylated Nonionic Surfactants
Standard Test Method for Ethylene Oxide Content of Polyethoxylated Nonionic Surfactants
ABSTRACT
This test method covers the determination of ethylene oxide content in polyethoxylated nonionic surfactants. It can also be used for compounds containing propylene oxide or any compounds (glycols and glycol and polyglycol ethers and esters) which form unstable 1,2-diiodides on reaction with hydroiodic acid. The apparatus is comprised of the following: heat source which shall be an electric heater provided with a sliding rheostat or other means of heat control; flasks which shall be equipped with a standard ground-glass joint; condensers with standard joints; gas bubbler filled with dibutyl phthalate; buret; and pipet. The dual apparatus is designed to permit a sample and a blank to be run simultaneously. Reagent grade chemicals or reagents of sufficiently high purity including water, carbon dioxide or nitrogen, lubricant, dibutyl phthalate, glass beads, hydroiodic acid, hydrochloric acid, methanol, potassium dichromate, potassium iodide solution, sodium thiosulfate, and starch indicator solution shall be used in all tests. The ethylene oxide content shall be calculated from the amount of sodium thiosulfate solution required to titrate the sample and the blank, normality of sodium thiosulfate, and weight of the sample. Standard deviations for repeatability and reproducibility shall be estimated to determine the acceptability of the results.
SCOPE
1.1 This test method covers the determination of ethylene oxide in polyethoxylated nonionic surfactants. It can also be used for compounds containing propylene oxide or any compounds (glycols and glycol and polyglycol ethers and esters) which form unstable 1,2-diiodides on reaction with hydriodic acid.
Note 1—Compounds in which the oxyalkylene group is connected to a nitrogen cannot be entirely decomposed. This can be used to determine the percent of an ethoxylated surfactant in a mixture, if the ethylene oxide content of the ethoxylated surfactant is known.
Note 2—This method reports results as percent ethylene oxide. If this method is applied to unknown compounds or compositions, the analyst should be aware of the possible presence of material other than ethylene oxide.
Note 3—For use on built syndet compositions the organic active ingredient must be isolated in accordance with Test Method D 2358.
1.2 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
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Designation:D2959–95(Reapproved 2003)
Standard Test Method for
Ethylene Oxide Content of Polyethoxylated Nonionic
Surfactants
This standard is issued under the fixed designation D2959; 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
1.1 This test method covers the determination of ethylene
oxide in polyethoxylated nonionic surfactants. It can also be
used for compounds containing propylene oxide or any com-
pounds (glycols and glycol and polyglycol ethers and esters)
which form unstable 1,2-diiodides on reaction with hydriodic
3.2 The percent ethylene oxide is determined by measuring
acid.
the amount of free iodine formed, since one mole of iodine is
NOTE 1—Compounds in which the oxyalkylene group is connected to a
formed for each mole of ethylene oxide in the polyoxyalkylene
nitrogencannotbeentirelydecomposed.Thiscanbeusedtodeterminethe
chain. The free iodine is titrated with a standard sodium
percent of an ethoxylated surfactant in a mixture, if the ethylene oxide
thiosulfate solution.
content of the ethoxylated surfactant is known.
NOTE 2—This method reports results as percent ethylene oxide. If this
4. Apparatus (Fig. 1)
method is applied to unknown compounds or compositions, the analyst
should be aware of the possible presence of material other than ethylene
4.1 Heat Sources, two. The source of heat should be an
oxide.
electric heater provided with a sliding rheostat or other means
NOTE 3—For use on built syndet compositions the organic active
of heat control.
ingredient must be isolated in accordance with Test Method D2358.
4.2 Flasks, two, 100-mL, round bottom. Each flask should
1.2 This standard does not purport to address all of the
be equipped with a standard ground-glass joint to accommo-
safety concerns, if any, associated with its use. It is the
date a vertical condenser, and with a side arm through which
responsibility of the user of this standard to establish appro-
carbon dioxide can be passed to blanket the reaction mixture.
priate safety and health practices and determine the applica-
4.3 Condensers, two, with standard joints to fit the flasks.
bility of regulatory limitations prior to use. Material Safety
4.4 Gas Bubbler, filled with dibutyl phthalate.
Data Sheets are available for reagents and materials. Review
4.5 Buret, 50-mL, with 0.1-mL graduations.
them for hazards prior to usage.
4.6 Pipet, 5-mL.
2. Referenced Documents
5. Reagents
2.1 ASTM Standards:
5.1 Purity of Reagents—Reagent grade chemicals shall be
D1193 Specification for Reagent Water
used in all tests. Unless otherwise indicated, it is intended that
D2358 Test Method for Separation of Active Ingredient
all reagents shall conform to the specifications of the Commit-
from Surfactant and Syndet Compositions
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
3. Summary of Test Method
used, provided it is first ascertained that the reagent is of
3.1 By cleaving nonionic surfactants containing polyethyl-
sufficiently high purity to permit its use without lessening the
ene oxide chains with hydriodic acid, the unstable 1,2-
accuracy of the determination.
diiodoethane is formed. This vicinal diiodide decomposes to
5.2 Purity of Water—Unless otherwise indicated, references
form ethylene and iodine.
to water shall be understood to mean Type III reagent water
conforming to Sections 1, 2, and 3 of Specification D1193.
This 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 of Soaps and Synthetic Detergents. Reagent Chemicals, American Chemical Society Specifications, American
Current edition approved March 15, 1995. Published May 1995. Originally Chemical Society, Washington, DC. For suggestions on the testing of reagents not
published as D2959 – 71 T. Last previous edition D2959 – 89. DOI: 10.1520/ listed by the American Chemical Society, see Analar Standards for Laboratory
D2959-95R03. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 11.01. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 15.04. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2959–95 (2003)
where:
N = normality of the Na S O solution,
2 2 3
C = grams of K Cr O used, and
2 2 7
D = millilitresofNa S O solutionrequiredfortitrationof
2 2 3
the solution.
5.13 Starch Indicator Solution—Make a homogeneous
paste of 10 g of soluble starch in water. To this add with rapid
stirring 1 L of boiling water and then cool. As a preservative,
add 1.25 g of salicylic acid per litre. Store the indicator in a
refrigerator at 4 to 10°C. Prepare fresh indicator when the
titration end point from blue to colorless fails to be sharp.
6. Procedure
6.1 Assemble the apparatus as shown in Fig. 1. Lubricate
the ground-glass joints with a very thin film of lubricant. The
dual apparatus is designed to permit a sample and a blank to be
run simultaneously; however, it should not be necessary to
make more than two blank determinations each day.
6.2 Accurately weigh a sample of such size that 4 to 5 meq
of iodine will be liberated (about 0.15 g of a nonionic
surfactant that contains 60 % ethylene oxide) into a 100-mL
round bottom flask. Pipet exactly 5.0 mL of HI into the flask,
and add a glass bead. Connect the vertical condenser to the
FIG. 1 Apparatus
flask using a thin seal of lubricant at the outer edge. Prepare a
blank by pipett
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