1、Designation:E172101(Reapproved 2015)Standard Test Method forDetermination of Acid-Insoluble Residue in Biomass1This standard is issued under the fixed designation E1721;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.INTRODUCTIONBiomass is composed largely of the following:cellulose,a polymer of glucose;hemicellulose,acomplex polymer,the main chain of w
3、hich consists of xylans or glucomannans;and lignin,a complexphenolic polymer.The lignin is mostly insoluble in mineral acids,unlike the other cell wallcomponents of biomass.For this reason,lignin can be analyzed gravimetrically after hydrolyzing thecellulose and hemicellulose fractions with sulfuric
4、 acid.1.Scope1.1 This test method covers determination of the acid-insoluble residue of hard and soft woods,herbaceous materials(such as switchgrass and sericea),agricultural residues(such ascorn stover,wheat straw,and bagasse),wastepaper(such asoffice waste,boxboard,and newsprint),acid and alkaline
5、pretreated biomass,and the solid fraction of fermentationresidues.All results are reported relative to the 105C oven-dried weight of the sample.1.2 The residue collected contains the acid-insoluble ligninand any condensed proteins from the original sample.Anindependent nitrogen analysis would be req
6、uired to determinethe acid-insoluble lignin content separate from the condensedprotein fraction and is outside the scope of this test method.1.3 A portion of the lignin in some biomass samples willremain soluble during this procedure.The total lignin in abiomass sample includes both acid-soluble lig
7、nin and lignin inthe acid insoluble residue.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the
8、 user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific hazardsstatements are given in Section 8 and Note 2 and Note 4.2.Referenced Documents2.1 ASTM Standards:2E1690 Test Method for Determination o
9、f Ethanol Extrac-tives in BiomassE1756 Test Method for Determination of Total Solids inBiomassE1757 Practice for Preparation of Biomass for Composi-tional Analysis3.Terminology3.1 Definitions:3.1.1 acid-insoluble residuethe solid residue,correctedfor acid-insoluble ash,retained on a medium-porosity
10、filtercrucible after the primary 72%and secondary 4%H2SO4hydrolysis described in this test method.This material isprimarily acid-insoluble lignin and any condensed proteins.3.1.2 prepared biomassmaterial that has been treated inaccordance with Practice E1757 in order to raise the total solidscontent
11、 above 85%,based on an oven-dried solids weight.4.Significance and Use4.1 The acid-insoluble residue content is used in conjunc-tion with other assays to determine the total composition ofbiomass samples.5.Interferences5.1 The results of acid-insoluble residue analysis are af-fected by the incomplet
12、e hydrolysis of biomass.The resultswill be biased high unless the sample is hydrolyzed completely.1This test method is under the jurisdiction of ASTM Committee E48 onBioenergy and Industrial Chemicals from Biomass and is the direct responsibility ofSubcommittee E48.05 on Biomass Conversion.Current e
13、dition approved June 1,2015.Published July 2015.Originally approvedin 1995.Last previous edition approved in 2009 as E1721-01(2009).DOI:10.1520/E1721-01R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMSta
14、ndards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Take care to mix the acid/biomass slurry thoroughly during theconcentrated acid hydrolysis.5.2 The r
15、esults of acid-insoluble residue analysis are af-fected by the timing of the acid digestion steps.The insolubleresidue will dissolve slowly into solution in an irreproduciblefashion.The timing within this test method must be followedclosely.6.Apparatus6.1 Analytical Balance,readable to 0.1 mg.6.2 Co
16、nvection Oven,with a temperature control of 105 63C.6.3 Muffle FurnaceAn electric furnace is recommendedfor igniting the sample.The furnace should be fitted with anindicating pyrometer or thermocouple so that the requiredtemperature of 575 6 25C can be maintained.6.4 Autoclave,capable of maintaining 121 6 3C.6.5 Water Bath,set at 30 6 1C.6.6 Desiccator,using anhydrous calcium sulfate.7.Reagents and Materials7.1 Chemicals:7.1.1 72%H2SO4,specific gravity 1.6389 6 0.0012 at15.6C/15.6C or 12.00 6 0.
