1、Designation: E 1690 08Standard Test Method forDetermination of Ethanol Extractives in Biomass1This standard is issued under the fixed designation E 1690; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 a
3、nd 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 test method ma
4、y 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 thesafet
5、y 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:2D 1107 Test Method for Ethanol-To
6、luene Solubility ofWoodE 1756 Test Method for Determination of Total Solids inBiomassE 1757 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 ar
7、eremoved 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 E 1756.3.1.3 prepared biomassthe biomass that has been pre-pared in accordance with
8、 Practice E 1757.4. 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 remove
9、s 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 Te
10、stMethod D 1107.5. 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
11、 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 E
12、thyl Alcohol, 190 proof, USP grade.7. Sampling7.1 The sample is milled material prepared in accordancewith Practice E 1757.8. 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.1This test method is unde
13、r the jurisdiction of ASTM Committee E48 onBiotechnology and is the direct responsibility of Subcommittee E48.05 on BiomassConversion.Current edition approved May 1, 2008. Published May 2008. Originallyapproved in 1995. Last previous edition approved in 2001 as E 1690-01.2For referenced ASTM standar
14、ds, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
15、19428-2959, United States.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 thimb
16、le. 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 3The samples for total solids determination should be weighedout at
17、 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 boiling chips into a 250-mL flask. Weighthe flask, with chi
18、ps, 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 periodically, and adjust the heating rateto provide four to five sol
19、vent 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 is com-plete, and transfer the sample carefully to a Buchner funnel.Remove any residual solvent by vacuum filtration, and washt
20、he sample thoroughly with 190 proof ethanol, collecting all ofthe filtrate. Allow the biomass to air dry in the Buchner funnelwhile it is still attached to the vacuum system.NOTE 4If the extractives-free sample is to be analyzed further, storethe air-dried extractives-free sample in a freezer at 10C
21、 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 vacuum (75 to 100torr). Use a water bath temperature of 45 6 5C to h
22、eat 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 room temperature in a desiccator. Weigh theflask to the nearest 0.1
23、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 preparedsample, g,Wst= weight of sample and thimble (8.2), g,Wt= tare weight of thimble (8.2), g, andT = percen
24、tage of total solids in the sample, as deter-mined in accordance with Test Method E 1756.9.2 Calculate the percent of extractives on a 105C oven-dried weight basis:% extractives 5 Wef2 Wf!/Ws# 3 100 % (2)where:% extractives = percentage of extractives based on theoven-dried weight,Wef= weight of ext
25、ractives, 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-driedweight of the sample.11. Precision and Bias11.1 Precision:11.1
26、.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. 8494 wheat straw yielded a standard deviation of0.20 % and
27、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 of the extractive residue maybias the reported results low be
28、cause 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; herbaceous;waste paper; woodE1690082ASTM International tak
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32、e address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United 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).E1690083
