1、Designation:D555995(Reapproved 2017)Standard Test Method forDetermination of Acidity as Free Fatty Acids/Acid Number inthe Absence of Ammonium or Triethanolamine Soaps inSulfonated and Sulfated Oils1This standard is issued under the fixed designation D5559;the number immediately following the design
2、ation indicates the year oforiginal adoption or,in the 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 covers the determinati
3、on of the acidityas free fatty acids existing in a sample of sulfonated or sulfatedoil,or both,by titrating the sample dissolved in a solvent.It isnot applicable in the presence of ammonium or triethanolaminesoaps or salts or other compounds that do not react neutral tophenolphthalein when dissolved
4、 in alcohol.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establ
5、ish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopmen
6、t of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Significance and Use2.1 This test method is intended for use in the determinationof the acidity as free fatty acids in the absence of ammoniumor triethanolamine
7、soaps in sulfonated and sulfated oils for thepurpose of quality assurance.3.Apparatus and Reagents3.1 Alcohol-Ether MixtureMix 50 mL of neutral alcoholwith 25 mL of ether.3.2 Phenolphthalein Indicator Solution(10 g/L)Dissolve1 g of phenolphthalein in 100 mL of ethanol(95%).3.3 Sodium Hydroxide,Stand
8、ard Solution(0.5 N)Prepare and standardize a 0.5 N solution of sodium hydroxide(NaOH).Potassium hydroxide(KOH)may be substituted forNaOH.4.Procedure4.1 The procedure consists of titrating a solution of thesample in a mixture of alcohol and ether in the presence ofphenolphthalein indicator.Dissolve 1
9、0 g of the sample in analcohol-ether mixture,add five drops of phenolphthalein indi-cator solution,and titrate the solution with 0.5 N NaOH orKOH solution until the pink color persists after vigorousshaking.5.Calculation5.1 Calculate the acidity as free fatty acids,as follows:K 5C 3E!/W(1)or%free fa
10、tty acids5 0.5033K(2)where:K=acid number,mg of KOH/g,C=mL of NaOH or KOH solution required for titration ofthe sample,E=strength of NaOH or KOH solution,mg of KOH/mL,andW=weight of sample,g.6.Precision and Bias6.1 This test method is adopted from the procedures of theAmerican Leather ChemistsAssocia
11、tion where it has long beenin use and was approved for publication before the inclusion ofprecision and bias statements was mandated.The originalinterlaboratory test data are no longer available.The user iscautioned to verify by the use of reference materials,ifavailable,that the precision and bias(
12、or reproducibility)of thistest method is adequate for the contemplated use.7.Keywords7.1 acidity;free fatty acids;leather;sulfonated and sulfatedoils1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.08 on Fats and Oils.Th
13、is testmethod was developed in cooperation with the American Leather Chemists Assn.(Method H 50-1956).Current edition approved April 1,2017.Published April 2017.Originallyapproved in 1994.Last previous edition approved in 2011 as D5559 95(2011).DOI:10.1520/D5559-95R17.Copyright ASTM International,10
14、0 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recomm
15、endations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard.Users of this standard are expressly advised that determinatio
16、n of the validity of any such patent rights,and the riskof infringement of such rights,are entirely their own responsibility.This standard 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 International Headquarters.Your comments will receive careful consideration at
