1、Designation:D555415(Reapproved 2021)Standard Test Method forDetermination of the Iodine Value of Fats and Oils1This standard is issued under the fixed designation D5554;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last
2、 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 iodinevalue of fats and oils.1.2 The values stated in SI units are to be regar
3、ded 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,health,and environmental practices an
4、d deter-mine the applicability 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,Guides and Recom-m
5、endations 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 theiodine value of fats and oils that do not contain conjugateddouble bonds.The iodine value is a measure of the unsaturationof fa
6、ts and oils and is expressed in terms of the number ofcentigrams of iodine absorbed per gram of sample.3.Apparatus and Reagents3.1 Glass-Stoppered Bottles or Wide Mouth ErlenmeyerFlasks,500 mL.Wide mouth bottles or flasks are essential ifstirring is done by mechanical means.3.2 Glass-Stoppered Volum
7、etric Flasks,conforming toNIST tolerances2and accurately calibrated to contain1000 mL.3.3 Pipette,20 mL.3.4 Two Pipettes,25 mL.One pipette is reserved for usewith the standard potassium dichromate solution and shallconform to NIST tolerances2and be calibrated to deliver25 mL.3.5 Glacial Acetic Acid,
8、A.C.S.grade.The permanganatetest shall be applied to be sure that this specification is met.3.5.1 Two millilitres of the glacial acetic acid shall bediluted with 10 mL of distilled water and 0.1 mL of 0.1 NKMnO4shall be added.The pink color shall not be entirelydischarged within 2 h.3.6 Potassium Io
9、dide,A.C.S.grade.3.7 Chlorine,99.8%.Satisfactory commercial grades areavailable in cylinders,but this gas must be dried by passingthrough sulfuric acid(sp.gr.1.84)before introducing into theiodine solution.3.7.1 Chlorine may be prepared by allowing hydrochloricacid(sp.gr.1.19)to drop onto potassium
10、permanganate or ona mixture of potassium permanganate and manganese dioxide.The gas thus generated shall be led through a glass tube intosulfuric acid(sp.gr.1.84)and then into the iodine solution.3.8 Carbon Tetrachloride,A.C.S.grade.(WarningCarbon Tetrachloride is a known carcinogen.It is toxic byin
11、halation,ingestion and skin absorption.Always handle Car-bon Tetrachloride inside a fume hood.Use only with adequateventilation.)3.9 Cyclohexane3,A.C.S.grade.3.10 Reagent for Diluting SamplePrepare by mixing freshcyclohexane and glacial acetic acid,1:1,v/v.(After mixing,verify the absence of oxidiza
12、ble matter in the reagent byshaking 10 mL of the reagent with 1 mL of saturated aqueouspotassium dichromate solution and 2 mL of concentratedsulfuric acid:no green coloration should appear.A greencoloration indicates presence of oxidizable matter,so discardand remix using fresh cyclohexane.)3.11 Hyd
13、rochloric Acid,A.C.S.grade,sp.gr.1.19.3.12 Soluble Starch,of suitable sensitivity.3.12.1 The test for starch sensitivity shall be made byadding,while stirring,200 mL of boiling water to a paste made1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsi
14、bility of Subcommittee D31.08 on Fats and Oils.This testmethod was developed in cooperation with the American Leather Chemists Assn.(Method H 32-1957).Current edition approved Dec.1,2021.Published January 2022.Originallyapproved in 1994.Last previous edition approved in 2015 as D5554 15.DOI:10.1520/
15、D5554-15R21.2Available from National Institute of Standards and Technology,(NIST),Gaithersburg,MD 20899.3Comparison study showed excellent agreement between Carbon Tetrachlorideand Cyclohexane(ISO/IUPAP Smalley program).Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken
16、,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 Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1?with 1 g of starch in a small amount of water.After placing5 mL of this solution in 100 mL of water,add 0.05 mL of 0.1N iodine solution.The deep blue color
