1、Designation: D6173 97 (Reapproved 2014)Standard Test Method forDetermination of Various Anionic Surfactant Actives byPotentiometric Titration1This standard is issued under the fixed designation D6173; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is based on a potentiometric titration ofcommon anionic surfactants and
3、 blends of anionic surfactantwith a hydrotrope. This test method solely is intended for theanalysis of active matter in the following surfactants: alcoholether sulfate, alpha olefin sulfonate, alkylbenzene sulfonicacid, alcohol sulfate, sodium alkylbenzene sulfonate/sodiumxylene sulfonate blend (5:1
4、), sodium alkylbenzene sulfonate/sodium xylene sulfonate blend (16:1), and sodium alkylben-zene sulfonate/sodium xylene sulfonate blend (22:1). It has notbeen tested for surfactant formulations.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are include
5、d in thisstandard.1.3 This standard does not purport to address all the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use. Mat
6、erial Safety Data Sheets areavailable for reagents and materials. Review them for hazardsprior to usage.2. Referenced Documents2.1 ASTM Standards:2D459 Terminology Relating to Soaps and Other DetergentsD1681 Test Method for Synthetic Anionic Active Ingredientin Detergents by Cationic Titration Proce
7、dureD3049 Test Method for Synthetic Anionic Ingredient byCationic Titration3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 active matter, nthe organic surface-active materialpresent in the detergent. Also defined in Terminology D459 asactive ingredient of detergents.4. Summary
8、 of Test Method4.1 This test method describes a potentiometric titrationprocedure for determining active matter in anionic surfactant.The anionic surfactant is first dissolved in water, and the pH ofthe solution is adjusted according to the type of anionicsurfactant being measured. In the potentiome
9、tric titration theanionic surfactant is titrated with a standard solution ofHyamine using a surfactant electrode, and the reaction involvesthe formation of a complex between the anionic surfactant andthe cationic titrant (Hyamine), which then precipitates. At theend point the surfactant electrode ap
10、pears to respond to anexcess of titrant with potential change large enough to give awell defined inflection in the titration curve.5. Significance and Use5.1 The most common anionic surfactants presented in thistest method are used widely in synthetic detergents and otherhousehold cleaners. Current
11、analysis of the active matter inthese anionic surfactants involves the two-phase aqueous/chloroform titration with a mixed indicator, organic dyes suchas disulphine blue/dimidium bromide (see Test MethodD3049), and methylene blue (see Test Method D1681). Thistest method eliminates the use of hazardo
12、us chloroform, theuse of which is restricted for environmental and toxicologicalreasons.5.2 This test method also describes the titration of variousratio blends of sodium alkylbenzene sulfonate and sodiumxylene sulfonate. Active matter content in these blends isattributable directly to sodium alkylb
13、enzene sulfonate.Therefore, the presence of various amounts of sodium xylenesulfonate in these blends does not interfere with the determi-nation of percent actives.1This test method is under the jurisdiction of ASTM Committee D12 on Soapsand Other Detergents and is the direct responsibility of Subco
14、mmittee D12.12 onAnalysis and Specifications of Soaps, Synthetics, Detergents and their Components.Current edition approved Jan. 1, 2014. Published February 2014. Originallyapproved in 1997. Last previous edition approved in 2005 as D6173-97(2005). DOI:10.1520/D6173-97R14.2For referenced ASTM standa
15、rds, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
16、19428-2959. United States16. Apparatus6.1 Autotitration System, equipped with a delivery buretsystem, 10 or 20-mL capacity.3,46.2 Phoenix Surfactant Combination Electrode3,4, nitratespecific ion electrode, or surfactant electrode4,5equipped withsilver/silver chloride reference electrode.5The conditi
17、oning ofthis type of electrode is essential for obtaining a good break inthe titration curve. Therefore, each electrode should be condi-tioned in sodium lauryl sulfate 0.0001M solution for 15 min.For other electrode requirements, follow the manufacturersinstruction manual.6.3 Analytical Balance.6.4
18、Standard Laboratory Glassware.7. Reagents67.1 Hyamine 1622, diisobutylphenoxyethoxyethyl dimethylbenzyl ammonium chloride monohydrate.7.2 Potassium Chloride, reagent grade.7.3 Triton X-1004,7, electrophoresis grade.7.4 Potassium Chloride 4.0 M SolutionPrepare by weigh-ing out 30.00 g to the nearest
19、0.01 g of potassium chloride intoa 100 mL volumetric glass and dissolving in deionized water.Dilute to the mark with deionized water.Add exactly one dropof Triton X-100 to the solution and mix well. This is only areference electrode filling solution for the Phoenix electrode.7.5 Triton X-100, 1 % So
20、lutionPrepare by weighing 1.00g of Triton X-100 into a 100-mL volumetric flask and dilutingto the mark with deionized water.7.6 Sodium Lauryl Sulfate4,8, primary standard.NOTE 1Sodium lauryl sulfate shall be analyzed for purity according tothe reagent section of Test Method D3049 before its use as p
21、rimarystandard.7.7 Buffer Solution pH 4.004,97.8 Buffer Solution pH 7.004,9Pipet 10 mL of buffersolution pH 7.00 and transfer to a 100-mL volumetric flask.Dilute to volume and mix well.7.9 Sodium Lauryl Sulfate 0.0001 m Solution, buffered atpH 4.00, with a graduated cylinder transfer 2 mL of sodiuml
22、auryl sulfate 0.004 M solution to a 150-mLbeaker.Add 80 mLof deionized water and 1 mL of buffer solution pH 4.00 andmix well. This solution is use for conditioning the electrodes.7.10 Electrode Rinse SolutionTransfer approximately 50mL of 0.1 M HCl solution to 1 L volumetric flask and dilute tovolum
23、e.8. Preparation of Primary Standard Reagents8.1 Sodium Lauryl Sulfate Solution, 410-3N. Weighaccurately 1.15 + 0.01 g of sodium lauryl sulfate to the nearest0.1 mg. Dissolve in water and dilute to a final volume of 1L.Calculate the normality of the solution according to thefollowing equation:Normal
24、ity of Sodium Lauryl Sulfate 5W 3P288.38 3100!(1)where:P = purity of the sodium lauryl sulfate, weight %, andW = weight of sodium lauryl sulfate, g.8.2 Keep the solution no longer than one month beforemaking a fresh solution.8.3 Hyamine 1622 Solution, 410-3NDissolve 1.85 +0.5 g of Hyamine 1622 in de
25、ionized water and dilute to a finalvolume of 1 L.8.4 Hyamine 1622 Solution Standardization, 410-3NThis determination shall be done in triplicate. Pipet 5.00mL of the standard lauryl sulfate solution into a 150-mLbeaker. Add 50 mL of dionized water, and, while stirring, add1 mL of buffer solution pH
26、4 and 1 mL of Triton-X-100, 1 %solution. To minimize noise in the titration, make sure that theburet tip is placed close to the center of the stir bar. Stirmoderately. Erroneous results can occur if excessive foamingtakes place. Titrate potentiometrically with the Hyamine 1622solution and record the
27、 titration volume. The Titroprocessorwill perform the titration, determine the inflection point andcalculate the results according to the following equation:Normality of Hyamine 1622 5N 35V(2)where:N = normality of sodium lauryl sulfate standard solution,5 = sodium lauryl sulfate aliquot taken for t
28、itration, mL,andV = Hyamine 1622 solution required to reach the endpoint,mL.8.5 The electrode should be cleaned between each titration.A satisfactory procedure is to first rinse with the acid rinsesolution and then with deionized water. Blot dry with a soft,lint-free tissue. For other electrodes fol
29、low the manufacturersinstructions.9. Hazards9.1 All reagents and chemicals shall be handled with care.Before using any chemical, read and follow all safety instruc-tions on the manufacturers label or MSDS (Material SafetyData Sheet).3The sole source of supply of the autotitration system and Phoenix
30、electrodeknown to the committee at this time is Brinkmann Instruments, Inc. Cantiague Rd.,Westbury, NY 11590.4If you are aware of alternative suppliers, please provide this information toASTM headquarters.Your comments will receive careful consideration at a meetingof the responsible technical commi
31、ttee, which you may attend.5The sole source of supply of the electrodes known to the committee at this timeis Orion Research, Inc., 529 Main St., Boston, MA 02129.6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of
32、 reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial Convention, Inc., (USPC), Rockville, MD.7The sole source of supply of Triton-X-100 known to
33、the committee at this timeis Fisher Scientific, 711 Forbes Ave., Pittsburgh, PA 15219-4785.8The sole source of supply of sodium lauryl sulfate known to the committee atthis time is Gallard Schlesinger Chemical Manufacturing Corp., 584 Mineola Ave.,Carle Place, NY 11514.9The sole source of supply of
34、buffer solution known to the committee at this timeis Fisher Scientific, 711 Forbes Ave., Pittsburgh, PA 15219-4785.D6173 97 (2014)210. Procedure for Determination of Actives in AnionicSurfactants10.1 Weigh a quantity of sample to the nearest 0.1 mg thatcontains approximately 0.016 meq/4.0 mL anioni
35、c surfactantactive material into a 1-L volumetric glass (see Note 2). Diluteto volume with deionized water. Mix well, and pipet thecorresponding aliquot. For the alcohol ether sulfate, or alphaolefin sulfonate sample, or both, add to the correspondingaliquot 70 mL of deionized water 1 mL of buffer s
36、olution pH7.00 and 1 mL of 1 % Triton-X-100 solution. Proceed with theanalysis section. For the alkylbenzene sulfonic acid or blendsof sodium alkylbenzene sulfonate with sodium xylene sul-fonate or alcohol sulfate samples add to the correspondingaliquot 70 mL of deionized water, 1 mL buffer solution
37、 pH4.00, and 1 mLof 1 % Triton-X-100 solution. Proceed with theanalysis section.NOTE 2To determine the amount of sample needed for an approxi-mately 5 to 7 mL titration of 0.0016 meq use the following equation:W 50.0016 3MD(3)where:W = weight of sample to take for analysis, g,M = average molecular w
38、eight of the anionic active matter present,andD = approximate concentration of anionic active matter expectedweight %.10.2 To obtain accurate weights of sample, it is convenientto dissolve the anionic surfactant in deionized water and takeand aliquot corresponding to a known meq of active matter. Fo
39、rexample, for an alcohol ether sulfate containing 58.1 % activesand molecular weight 441, weigh 3.0 g of sample into a 1-Lvolumetric flask dilute with water, and take a 4-mL aliquot.Add 70 mL of deionized water, 1 mL of the correspondingbuffer solution, and 1 mL of 1 % Triton-X-100 solution.11. Anal
40、ysis11.1 Titrate potentiometrically with the standardizedHyamine 1622 solution, and record the titration volume. Theendpoint is marked by the point of inflection on S-shapedcurve. Autotitration systems performs the titration, determinesthe inflection point, and calculates the result.12. Calculation1
41、2.1 Calculation of percent actives in anionic surfactants asfollows:Anionics, weight % 5A 3N 3M 3D 31000 3100S 31000 3A1(4)where:A = standard Hyamine 1622 solution required for titration,mL,N = normality of standard Hyamine 1622 solution,M = molecular weight of anionic surfactant,D = initial dilutio
42、n of sample, mL,S = weight of sample, g, andA 1 = aliquot taken for titration, mL.13. Precision and Bias1013.1 Repeatability (Single Analyst)The standard deviationof results, each the average of duplicates, obtained by the sameanalyst on different days, has been estimated to be 0.25 %relative at 27
43、df. Two such averages should be consideredsuspect, 95 % confidence level, if they differ by more than 0.70weight % relative.13.2 Reproducibility (Multilaboratory):13.2.1 Alcohol SulfateThe standard deviation of results,each the average of duplicates, obtained by analysts in differentlaboratories, ha
44、s been estimated to be 0.43 % relative at 6 df.Two such averages should be considered suspect, 95 % confi-dence level, if they differ by more than 1.2 % relative.13.2.2 Alcohol Ether SulfateThe standard deviation ofresults, each the average of duplicates, obtained by analysts indifferent laboratorie
45、s, has been estimated to be 0.85 % relativeat 6 df. Two such averages should be considered suspect 95 %confidence level, if they differ by more than 2.4 % relative.13.2.3 Alkylbenzene Sulfonic AcidThe standard deviationof results, each the of average duplicates, obtained by analystsin different labo
46、ratories, has been estimated to be 0.79 %relative at 6 df. Two such averages should be consideredsuspect, 95 % confidence level, if they differ by more than2.2 % relative.13.2.4 Alpha Olefin SulfonateThe standard deviation ofresults, each the average of duplicates, obtained by analysts indifferent l
47、aboratories, has been estimated to be 0.82 % relativeat 6 df. Two such averages should be considered suspect, 95 %confidence level, if they differ by more than 2.3 % relative.13.2.5 Sodium Alkylbenzene Sulfonate/Sodium Xylene Sul-fonate (5:1)The standard deviation of results, each theaverage of dupl
48、icates, obtained by analysts in differentlaboratories, has been estimated to be 0.52 % relative. Twosuch averages should be considered suspect, 95 % confidencelevel if they differ by more than 1.5 % relative.13.2.6 Sodium Alkylbenzene Sulfonate/Sodium Xylene Sul-fonate (16:1)The standard deviation o
49、f results, each theaverage of duplicates, obtained by analysts in differentlaboratories, has been estimated to be 0.49 % relative at 6 df.Two such averages should be considered suspect, 95 % confi-dence level, if they differ by more than 1.3 % relative.13.2.7 Sodium Alkylbenzene Sulfonate/Sodium Xylene Sul-fonate (22:1)The standard deviation of results, each theaverage of duplicates, obtained by analysts in differentlaboratories, has been estimated to be 0.45 % relative at 6 df.Two such averages should be considered suspect, 95 % confi-dence level, if they diff
