ASTM D5558-1995(2017) Standard Test Method for Determination of the Saponification Value of Fats and Oils《测定脂肪和油中皂化值的标准试验方法》.pdf

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1、Designation: D5558 95 (Reapproved 2017)Standard Test Method forDetermination of the Saponification Value of Fats and Oils1This standard is issued under the fixed designation D5558; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th

2、e 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 determination of the saponi-fication value of fats and oils.1.2 The values state

3、d 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 establish appro-priate safety and

4、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 theDevelopment of International Standards

5、, 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 saponification value of fats and oils used in themanufacture of fat liquors for the purpose of qu

6、ality assurance.3. Apparatus and Reagents3.1 Erlenmeyer Flasks, Corning2alkali resistant, Kimbleresistant, or equivalent, 250 or 300 mL.3.2 Air Condensers, minimum length 650 mm.3.3 Water Bath or a Hot Plate, with variable heat control.3.4 Hydrochloric Acid, 0.5 N, accurately standardized.3.5 Alcoho

7、lic Potassium Hydroxide,3added to a 2-L flaskfrom 1 to 1.5 L of 95 % ethyl alcohol (U.S.S.D. Formula 3A2is permitted) and a few grams (5 to 10 g) of potassiumhydroxide. After boiling under a reflux condenser on a waterbath for 30 to 60 min, the alcohol shall be distilled andcollected. For the prepar

8、ation of alcoholic potassiumhydroxide, 40 g of potassium hydroxide, low in carbonate,shall be dissolved in 1 L of the distilled alcohol, keeping thetemperature below 15.5C (60F) while the alkali is beingdissolved. This solution should remain clear.4. Procedure4.1 Melt the sample, if not already liqu

9、id, and filter throughfilter paper to remove any impurities and the last traces ofmoisture. The sample must be completely dry.4.2 Accurately weigh a sample, of such size (usually 4 to 5g) that the back titration is 45 to 55 % of the blank, and 50 mLof the alcoholic KOH is added with a pipette, allow

10、ing thepipette to drain for a definite period of time.4.2.1 Prepare a blank determination and conduct simultane-ously with the sample.4.3 Connect air condensers to the flask and boil the solutiongently but steadily until the sample is completely saponified.This usually requires approximately 1 h for

11、 normal samples.Take care that the vapor ring in the condenser does not rise tothe top of the condenser or there may be some loss.NOTE 1Some samples particularly difficult to saponify may requiremore than 1 h. This can only be determined by trial. Clarity andhomogeneity of the test solution are part

12、ial indicators of the completesaponification, but they are not necessarily absolute criteria.4.4 After the flask and condenser have cooled somewhat,but not sufficiently to jell the contents, wash down the inside ofthe condenser with a little distilled water. Then disconnect theflask, add approximate

13、ly 1 mL of indicator, and titrate thesolution with 0.5 N HCl until the pink color has just disap-peared.5. Calculation and Report5.1 Calculate the saponification number as follows:saponification value 528.05A 2 B!weight of sample(1)where:A = titration of blank, andB = titration of sample.1This test

14、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 Chemists Assn.(Method H 31-1957).Current edition approved April 1, 2017. Published April 2

15、017. Originallyapproved in 1994. Last previous edition approved in 2011 as D5558 95(2011).DOI: 10.1520/D5558-95R17.2Product is widely available commercially.3Alternately, commercially available potassium hydroxide solution 0.5 Nmmethanol is said to work satisfactorily.Copyright ASTM International, 1

16、00 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

17、Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.2 Reference this test method as the procedure used in thetest report.6. Precision and Bias6.1 This test method is adopted from the procedures of theAmerican Leather ChemistsAssociation where it has

18、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 (or reproducib

19、ility) of thistest method is adequate for the contemplated use.7. Keywords7.1 fats and oils; leather; saponification valueASTM 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 expre

20、ssly advised that determination 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

21、, 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 a meeting of theresponsible technical committee, which you may a

22、ttend. 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 below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States

23、. 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). 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:/ 95 (2017)2