ASTM_D_4900_-_99_2020.pdf

Designation:D490099(Reapproved 2020)Standard Test Method forLignosulfonates(Sulfite Cellulose)in Tanning Extracts1This standard is issued under the fixed designation D4900;the number immediately following the designation 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 is intended for use in detecting thepresence of lignosulfonates(sulfite cellulose)in extracts oftanning materials.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 establish appro-priate safety,health,and environmental practices and 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-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D4901 Practice for Preparation of Solution of Liquid Veg-etable Tannin ExtractsD4905 Practice for Preparation of Solution of Solid,Pastyand Powdered Vegetable Tannin ExtractsD6404 Practice for Sampling Vegetable Materials Contain-ing TanninD6405 Practice for Extraction of Tannins from Raw andSpent Materials2.2 ALCA Methods:A50 Lignosulfonates(Sulfite Cellulose)33.Summary of Test Method3.1 The reaction with aniline of a tanning material extractspecimen is compared with that of a solution containinglignosulfonate and tanning material known to be free fromlignosulfonate.4.Significance and Use4.1 This test method is useful to detect possible adulterationof tanning material extract with cheap and inferior lignosul-fonates.5.Specimen5.1 The sample shall be drawn as described in PracticeD6404.5.2 The specimen shall consist of 5 mL of a solution ofanalytical strength(4.0 g tannin per L),prepared as describedin Practices D4901,D4905,and Practice D6405.6.Apparatus and Reagents6.1 Aniline.6.2 Hydrochloric Acid,concentrated.6.3 Comparison SolutionThis shall contain lignosulfonate(sulfite cellulose)in the proportion of 1 g total solids to 2000mL of solution,and as much tanning material,similar to and ofthe same type as that being tested but known to be free fromlignosulfonate,as will make up the solution to analyticalstrength.7.Procedure7.1 Place the specimen in a test tube.Add 0.5 mL of aniline,and shake well.Add 2 mL of concentrated hydrochloric acid,and again shake mixture well.8.Results8.1 If at least as much precipitate remains at the end of 15min as is obtained when the comparison solution is similarly1This test method is under the jurisdiction of ASTM Committee D31 on Leatherand is the direct responsibility of Subcommittee D31.01 on Vegetable Leather.Thistest method has been adapted from,and is a replacement for,Method A50 of theOfficial Methods of the American Leather Chemists Association.Current edition approved Dec.1,2020.Published December 2020.Originallyapproved in 1989.Last previous edition approved in 2016 as D4900 99(2016).DOI:10.1520/D4900-99R20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Official Methods of the American Leather Chemists Association.Availablefrom the American Leather Chemists Association,University of Cincinnati,P.O.Box 210014,Cincinnati,OH 452210014.Copyright ASTM International,100 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 Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1treated,the material shall be held to contain lignosulfonates(sulfite cellulose)and the fact shall be noted on the analysisreport.8.2 Attention is drawn to the fact that some synthetictannins give precipitates under the conditions of this testmethod.9.Precision and Bias9.1 This test method is adopted from the procedures of theAmerican Leather Chemists Association,3where it has longbeen in use and where it was approved for publication beforethe inclusion of precision and bias statements was mandated.The original interlaboratory test data are no longer available.The user is cautioned to verify by the use of referencematerials,if available,that the precision and bias of this testme