1、Designation: E1690 08 (Reapproved 2016)Standard 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 l
2、ast 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-driedbio
3、mass, 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.NOTE 1This
4、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 a
5、ll 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 f
6、or 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 mater
7、ials 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 acco
8、rdance 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 extract
9、ion 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 compar
10、able 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
11、.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 Mater
12、ials6.1 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 E48.0
13、5 on Biomass Conversion.Current edition approved June 1, 2016. Published July 2016. Originally approvedin 1995. Last previous edition approved in 2008 as E1690-08. DOI: 10.1520/E1690-08R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
14、eastm.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 States18. Procedure8.1 Dry the Soxhlet extraction thimble in a dr
15、ying 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
16、 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.NOTE 2The precision for quantitation of the extractives weight isbased on a nominal 7-g prepared sample weight. Smaller samples willintroduce a larger relative error.NOTE
17、 3The 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
18、 several boiling chips into a 250-mL flask. Weighthe flask, with chips, to the nearest 0.1 mg, and record thisweight as the tare weight of the flask, Wf.8.4 Assemble the Soxhlet apparatus using at least 160 mLof190 proof ethanol. Insert the thimble, and heat at reflux for 24h. Check the reflux rate
19、periodically, and adjust the heating rateto provide four to five solvent exchanges per hour in theSoxhlet thimble. Approximately 100 to 120 solvent exchangesare required during the 24-h period.8.5 Remove the thimble when the extraction time iscomplete, and transfer the sample carefully to a Buchnerf
20、unnel. Remove any residual solvent by vacuum filtration, andwash the sample thoroughly with 190 proof ethanol, collectingall of the filtrate. Allow the biomass to air dry in the Buchnerfunnel while it is still attached to the vacuum system.NOTE 4If the extractives-free sample is to be analyzed furth
21、er, storethe air-dried extractives-free sample in a freezer at 10C until needed.8.6 Combine the filtrate from the previous step and anysolvent from the upper section of the Soxhlet apparatus withthe solvent in the 250-mL flask. Place the flask on the rotaryevaporator, and remove the solvent under va
22、cuum (75 to 100torr). Use a water bath temperature of 45 6 5C to heat theflask during evaporation.8.7 Place the flask in a vacuum oven (75 to 100 torr) at 406 1C for 24 6 1 h after all of the visible solvent is removedby the rotary evaporator. Remove the flask at this time, andallow it to cool to ro
23、om temperature in a desiccator. Weigh theflask to the nearest 0.1 mg. Record this weight as Wef.9. Calculation9.1 Calculate the weight of oven-dried biomass used for theextraction:Ws5 Wst2 Wt! 3 T/100%! (1)where:Ws= weight of moisture-free solids in the prepared sample,g,Wst= weight of sample and th
24、imble (8.2), g,Wt= tare weight of thimble (8.2), g, andT = percentage of total solids in the sample, as determinedin accordance with Test Method E1756.9.2 Calculate the percent of extractives on a 105C oven-dried weight basis:% extractives 5 Wef2 Wf!/Ws# 3100% (2)where:% extractives = percentage of
25、extractives based on theoven-dried weight,Wef= weight of extractives, flask, and boilingstones (8.7), g,Wf= tare weight of flask with boiling stones(8.3), g, andWs= weight of moisture-free solids in the pre-pared sample (9.1), g.10. Report10.1 Report the percent extractives based on the oven-driedwe
26、ight of the sample.11. Precision and Bias11.1 Precision:11.1.1 Data obtained by replicate testing of a hybrid poplarsample in one laboratory yielded a standard deviation inextractive content of 0.15 % and a CV % of 7.6 %. Replicatetesting of a National Institute of Standards and Technology(NIST) No.
27、 8494 wheat straw yielded a standard deviation of0.20 % and a CV % of 1.6 %, and NIST No. 8493 Pinus radiata(Monterey Pine) yielded a standard deviation of 0.20 % and aCV % of 8.0 %.11.1.2 No data are available at this time on replicate testingin independent laboratories.11.2 BiasProlonged heating o
28、f the extractive residue maybias the reported results low because of the evaporation ofsemivolatile constituents. Insufficient heating or using inad-equate vacuum can bias the results high because of incompleteremoval of the ethanol solvent.12. Keywords12.1 agricultural residue; biomass; extractives
29、; herbaceous;waste paper; woodE1690 08 (2016)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, a
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