ASTM_E_1690_-_08.pdf

Designation:E169008Standard Test Method forDetermination of Ethanol Extractives in Biomass1This standard is issued under the fixed designation E1690;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 covers the determination of ethanolsoluble extractives,expressed as a percentage of the oven-driedbiomass,of hard and soft woods,herbaceous materials(such asswitchgrass and sericea),agricultural residues(such as cornstover,wheat straw,and bagasse),and wastepaper(such asoffice waste,boxboard,and newsprint).All results are reportedrelative to the oven-dried weight of the sample.NOTE1This test method may not be suitable for hard and soft woodsamples that include bark or those with more than 10%extractablematerials.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1107 Test Method for Ethanol-Toluene Solubility of WoodE1756 Test Method for Determination of Total Solids inBiomassE1757 Practice for Preparation of Biomass for Composi-tional Analysis3.Terminology3.1 Definitions:3.1.1 ethanol extractivesthe residue remaining afterevaporation of the ethanol solvent.These are materials that areremoved from the biomass by extraction with 190 proofethanol.3.1.2 oven-dried weightthe moisture-free correctedweight of the prepared biomass sample.The correction factoris determined in accordance with Test Method E1756.3.1.3 prepared biomassthe biomass that has been pre-pared in accordance with Practice E1757.4.Significance and Use4.1 Ethanol extractives are any materials found in biomassthat are soluble in ethanol.They are not considered to be partof the structural components of biomass and should be re-moved prior to any chemical analysis of the sample.Theprolonged extraction removes nonstructural materials that caninclude waxes,fats,resins,tannins,gums,sugars,starches,andpigments.Removing hydrophobic materials from the biomassmakes it easier to wet the material for the analysis of structuralcomponents in the biomass.4.2 This test method yields results comparable to TestMethod D1107.5.Apparatus5.1 Soxhlet Extraction Apparatus,glass,of a size(100 mL)suitable for containing the sample and a 250-mL collectionflask.5.2 Alundum Extraction Thimbles,medium porosity(10 to15-m pore),sized to fit the Soxhlet extractor.5.3 Analytical Balance,sensitive to 0.1 mg.5.4 Rotary Evaporator with Vacuum and Water Bath,con-figured with a“bump”or safety trap,condenser,and receivingvessel.A water aspirator will generally provide sufficientvacuum(150 torr).5.5 Vacuum Oven,controllable to 40 6 1C and withvacuum between 75 and 100 torr.6.Reagents and Materials6.1 Ethyl Alcohol,190 proof,USP grade.7.Sampling7.1 The sample is milled material prepared in accordancewith Practice E1757.1This 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 edition approved May 1,2008.Published May 2008.Originallyapproved in 1995.Last previous edition approved in 2001 as E1690-01.DOI:10.1520/E1690-08.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Procedure8.1 Dry the Soxhlet extraction thimble in a drying oven at105C overnight.Remove it and allow it to cool to roomtemperature in a desiccator.8.2 Weigh the Soxhlet extraction thimble to the nearest 0.1mg,and record the weight as Wt.Add a suitable quantity ofsample to the extraction thimble.Do not over fill the thimble;the largest sample should still leave approximately 1 cm of freespace in the top of the thimble.Weigh to the nearest 0.1 mg,and record this weight as Wst.NOTE2The precision for quantitation of the extractives weight isbased on a nominal 7-g prepared sample weight.Smaller samples willintroduce a larger relative error.NOTE3The samples for total solids determination should be weighedout at the same time as those for extractives determination.If this isperformed at a later time,it can introduce an error in the calculationbecause ground biomass can gain or lose moisture rapidly when exposedto the atmosphere.8.3 Place several boi