1、Designation: D5555 95 (Reapproved 2017)Standard Test Method forDetermination of Free Fatty Acids Contained in Animal,Marine, and Vegetable Fats and Oils Used in Fat Liquorsand Stuffing Compounds1This standard is issued under the fixed designation D5555; the number immediately following the designati
2、on 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 determi
3、nation of the freefatty acid content of fats and oils.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespon
4、sibility 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.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established
5、in the Decision on Principles for theDevelopment 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 the determination of thefree fatty acids contained in
6、 animal, marine, and vegetable fatsand oils for the purpose of quality assurance.3. Apparatus and Reagents3.1 Oil Sample Bottles, 115 or 230 mL (4 or 8 oz) or 250 mLErlenmeyer flasks.3.2 Ethyl Alcohol, 95 %. The alcohol shall give a definite,distinct, and sharp end-point with phenolphthalein and sha
7、ll beneutralized with alkali to a faint but permanent pink color justbefore using. (Isopropanol, 99 %, may be used as an alternatesolvent with crude and refined vegetable oils.)3.3 Phenolphthalein Indicator Solution, 1 % in 95 % alco-hol.3.4 Sodium Hydroxide Solution, accurately standardized.4. Proc
8、edure4.1 Use Table 1 to determine the quantities to be used withvarious ranges of fatty acids.4.2 The sample shall be entirely liquid and well mixedbefore weighing. Then weigh the designated sample size intoan oil-sample bottle or Erlenmeyer flask; add to that thespecified amount of hot, neutralized
9、 alcohol and 2 mL ofindicator.4.3 Shaking vigorously, make the titration with alkali to theappearance of the first permanent pink color of the sameintensity as that of the neutralized alcohol before adding thesample. The color shall persist for 30 s.5. Calculation and Report5.1 Report the free fatty
10、 acids in percent, by weight:% free fatty acids 5mL of alkali 3N 3 28.2weight of sample(1)5.2 Reference this test method in the test report.5.3 The free fatty acids are frequently expressed in terms ofacid value instead of percent free fatty acids. The acid value isdefined as the number of milligram
11、s of KOH necessary toneutralize1gofsample. To convert percent free fatty acids (asoleic) to acid value, multiply the former by 1.99.6. Precision and Bias6.1 This test method is adopted from the procedures of theAmerican Leather ChemistsAssociation where it has long beenin use and was approved for pu
12、blication 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 (or reproducibility) of thistest method is adequate f
13、or the contemplated use.7. Keywords7.1 fats and oils; free fatty acids; leather1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.08 on Fats and Oils. This testmethod was developed in cooperation with the American Leather
14、Chemists Assn.(Method H 30-1957).Current edition approved April 1, 2017. Published April 2017. Originallyapproved in 1994. Last previous edition approved in 2011 as D5555 95(2011).DOI: 10.1520/D5555-95R17.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2
15、959. 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 Recommendations issued by the World Trade Organization Technical
16、 Barriers to Trade (TBT) Committee.1ASTM 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 determination of the validity of any such patent rights, and the ris
17、kof 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 thi
18、s standard or for additional standardsand should be addressed to ASTM International 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
19、your views known to the ASTM Committee on Standards, at the address shown below.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
20、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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1 Suggested Quantity of Material to TestSample, g Alcohol, mL Normality of AlkaliFree Fatty AcidRange (%)56.4 0.2 50 0.1 0.0 to 0.228.2 0.2 50 0.1 0.2 to 1.07.05 0.05 75 0.25 1.0 to 30.07.05 0.05 100 0.25 or 1.0 30.0 to 50.03.525 0.001 100 1.0 50.0 to 100.0D5555 95 (2017)2
