1、Designation: D 2959 95 (Reapproved 2003)Standard Test Method forEthylene Oxide Content of Polyethoxylated NonionicSurfactants1This standard is issued under the fixed designation D 2959; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of ethyleneoxide in polyethoxylated nonionic surfactants. It
3、 can also beused 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 hydriodicacid.NOTE 1Compounds in which the oxyalkylene group is connected to anitrogen cannot be entirely decomposed. Th
4、is can be used to determine thepercent of an ethoxylated surfactant in a mixture, if the ethylene oxidecontent of the ethoxylated surfactant is known.NOTE 2This method reports results as percent ethylene oxide. If thismethod is applied to unknown compounds or compositions, the analystshould be aware
5、 of the possible presence of material other than ethyleneoxide.NOTE 3For use on built syndet compositions the organic activeingredient must be isolated in accordance with Test Method D 2358.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
6、s theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Material SafetyData Sheets are available for reagents and materials. Reviewthem for hazards prior to usage.2. Referenced Doc
7、uments2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 2358 Test Method for Separation of Active Ingredientfrom Surfactant and Syndet Compositions33. Summary of Test Method3.1 By cleaving nonionic surfactants containing polyethyl-ene oxide chains with hydriodic acid, the unstable 1,2-diio
8、doethane is formed. This vicinal diiodide decomposes toform ethylene and iodine.3.2 The percent ethylene oxide is determined by measuringthe amount of free iodine formed, since one mole of iodine isformed for each mole of ethylene oxide in the polyoxyalkylenechain. The free iodine is titrated with a
9、 standard sodiumthiosulfate solution.4. Apparatus (Fig. 1)4.1 Heat Sources, two. The source of heat should be anelectric heater provided with a sliding rheostat or other meansof heat control.4.2 Flasks, two, 100-mL, round bottom. Each flask shouldbe equipped with a standard ground-glass joint to acc
10、ommo-date a vertical condenser, and with a side arm through whichcarbon dioxide can be passed to blanket the reaction mixture.4.3 Condensers, two, with standard joints to fit the flasks.4.4 Gas Bubbler, filled with dibutyl phthalate.4.5 Buret, 50-mL, with 0.1-mL graduations.4.6 Pipet, 5-mL.5. Reagen
11、ts5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades m
12、ay beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type III reagent waterconforming to Sections 1
13、, 2, and 3 of Specification D 1193.1This method is under the jurisdiction of ASTM Committee D12 on Soaps andOther Detergents and is the direct responsibility of Subcommittee D12.12 onAnalysis of Soaps and Synthetic Detergents.Current edition approved March 15, 1995. Published May 1995. Originallypub
14、lished as D 2959 71 T. Last previous edition D 2959 89.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 15.04.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by t
15、he American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
16、hocken, PA 19428-2959, United States.5.3 Carbon Dioxide or Nitrogen, cylinder gas.5.4 Lubricant for ground-glass joints.5.5 Dibutyl Phthalate.5.6 Glass Beads.5.7 Hydriodic Acid (55 to 58 %) (suitable for methoxyldeterminations)The hydriodic acid (HI) should not containhypophosphorus acid (H3PO2) sta
17、bilizer. The free iodine con-tent should be less than 10 mL of 0.1 N sodium thiosulfatesolution/5 mL of HI.5.8 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).5.9 Methanol.5.10 Potassium Dichromate (K2Cr2O7), primary standard.5.11 Potassium Iodide Solution (200 g/L)Dissolve 200 g
18、of potassium iodide (KI) in distilled water and dilute to 1000mL.5.12 Sodium Thiosulfate, Standard Solution (0.1 N)Dissolve 24.8 g of sodium thiosulfate (Na2S2O3) in water anddilute to 1000 mL. Standardize by accurately weighing 0.16 to0.22 g of finely ground and dried K2Cr2O7into a 500-mLiodine fla
19、sk. Dissolve in 25 mL of water, add 5 mL of HCl and15 mL of KI solution and swirl to mix. Allow to stand for 5min, then add 100 mL of distilled water. Titrate with standardNa2S2O3solution, shaking continuously until the yellow colorhas almost disappeared. Add a small amount of Paragonindicator5or 1
20、to 2 mL of starch indicator solution and continuethe titration, adding the Na2S2O3solution slowly until the bluecolor has just disappeared. Calculate the normality of theNa2S2O3solution as follows:N 5 C/0.04904 3 D! (1)where:N = normality of the Na2S2O3solution,C = grams of K2Cr2O7used, andD = milli
21、litres of Na2S2O3solution required for titration ofthe solution.5.13 Starch Indicator SolutionMake a homogeneouspaste of 10 g of soluble starch in water. To this add with rapidstirring 1 L of boiling water and then cool. As a preservative,add 1.25 g of salicylic acid per litre. Store the indicator i
22、n arefrigerator at 4 to 10C. Prepare fresh indicator when thetitration end point from blue to colorless fails to be sharp.6. Procedure6.1 Assemble the apparatus as shown in Fig. 1. Lubricatethe ground-glass joints with a very thin film of lubricant. Thedual apparatus is designed to permit a sample a
23、nd a blank to berun simultaneously; however, it should not be necessary tomake more than two blank determinations each day.6.2 Accurately weigh a sample of such size that 4 to 5 meqof iodine will be liberated (about 0.15 g of a nonionicsurfactant that contains 60 % ethylene oxide) into a 100-mLround
24、 bottom flask. Pipet exactly 5.0 mL of HI into the flask,and add a glass bead. Connect the vertical condenser to theflask using a thin seal of lubricant at the outer edge. Prepare ablank by pipetting 5.0 mL of HI into a second flask containinga glass bead. Connect the condenser as described above, a
25、ndallow water to circulate through the condensers.6.3 Attach the tubes from the carbon dioxide manifold to thesidearms on the flasks. Open the valve on the gas cylinder andadjust the flow to a rate of 1 to 5 bubbles per second throughthe bubbler, blanketing the solutions in the reaction flasks. Thef
26、low of carbon dioxide should continue for 10 min before heatis applied to the reaction flasks. After 10 min turn on the heat,and reflux the contents gently for 90 min.6.4 After the 90-min boiling period, wash the walls of eachcondenser with 15 mL of 20 % KI solution to dissolve any freeiodine in the
27、 condensers. Wash the condensers with two 10-mLportions of water and disconnect. Wash the tips of the con-densers with water, adding the washings to the flasks. Transferthe contents of the reaction flasks to Erlenmeyer flasks bywashing with water.NOTE 4Rinse any iodine that adheres to the condensers
28、 into the flaskswith a small amount of methanol. On rare occasions some samples leavea tarry residue as a button. Add methanol to dissolve the residue, and washinto the Erlenmeyer flask.6.5 Titrate with standard Na2S2O3solution, shaking con-tinuously until the yellow color has almost disappeared. Ad
29、d asmall amount of Paragon indicator or 1 to 2 mL of starchindicator solution and continue the titration, adding theNa2S2O3solution slowly until the blue color has just disap-peared.7. Calculation7.1 Calculate the ethylene oxide content as follows:Ethylene oxide, weight % 5 A 2 B! 3 N 3 2.203#/W (2)
30、where:5Paragon indicator for iodine titrations may be purchased from Eastern Chemi-cal Corp., 34 Spring St., Newark, NJ 07104.FIG. 1 ApparatusD 2959 95 (2003)2A = millilitres of Na2S2O3solution required to titrate thesample,B = millilitres of Na2S2O3solution required to titrate theblank,N = normalit
31、y of Na2S2O3solution, andW = grams of sample.8. Precision and Bias8.1 The following criteria should be used for judging theacceptability of results (Note 5):8.1.1 Repeatability (Single Analyst)The standard devia-tion of results obtained by the same analyst was estimated to be0.47 % absolute at 9 df.
32、 Two such values should be consideredsuspect (95 % confidence level) if they differ by more than1.5 % absolute.8.1.2 Reproducibility (Multilaboratory)6The standard de-viation of results (each the average of duplicate determina-tions), obtained by analysts in different laboratories, has beenestimated
33、 to be 1.81 % absolute at 7 df. Two such valuesshould be considered suspect (95 % confidence level) if theydiffer by more than 6.0 % absolute.NOTE 5The precision estimates are based on an interlaboratory studyon Igepal CO 630 by nine laboratories. However, this procedure as writtencalls for the use
34、of 100-mL reaction flasks (instead of 50-mL flasks whichwere used in the interlaboratory study). Data obtained by Continental OilCo. indicate an improvement in precision when the larger flask is used.9. Keywords9.1 ethylene oxide content; nonionic surfactantsASTM International takes no position resp
35、ecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This s
36、tandard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Interna
37、tional Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown bel
38、ow.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).6Data supporting the precision statements are on file at ASTM Headquarters, 100Barr Harbor Drive, West Conshohocken, PA 19428, Research Report No. D12-1000.D 2959 95 (2003)3
