1、Designation: D5559 95 (Reapproved 2011)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 de
2、signation 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
3、determination 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
4、when dissolved 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
5、standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.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 s
6、oaps 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, S
7、tandard 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.
8、Dissolve 10 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 5 C 3 E
9、/W (1)or% free fatty acids 5 0.503 3 K (2)where:K = acid number, mg of KOH/g,C = mL of NaOH or KOH solution required for titrationof the 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 t
10、heAmerican Leather ChemistsAssociation 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, ifa
11、vailable, that the precision and bias (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 responsibilit
12、y of Subcommittee D31.08 on Fats and Oils. This testmethod was developed in cooperation with the American Leather Chemists Assn.(Method H 50-1956).Current edition approved Jan. 1, 2011. Published March 2011. Originallyapproved in 1994. Last previous edition approved in 2006 as D5559 95(2006).DOI: 10
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16、h you may attend. 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,Un
17、ited States. 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 ASTM website (www.astm.org/COPYRIGHT/).D5559 95 (2011)2
