ASTM E1690-08(2021)

Standard Test Method for Determination of Ethanol Extractives in Biomass

SIGNIFICANCE AND USE
4.1 Ethanol extractives are any materials found in biomass that are soluble in ethanol. They are not considered to be part of the structural components of biomass and should be removed prior to any chemical analysis of the sample. The prolonged extraction removes nonstructural materials that can include waxes, fats, resins, tannins, gums, sugars, starches, and pigments. Removing hydrophobic materials from the biomass makes it easier to wet the material for the analysis of structural components in the biomass.  
4.2 This test method yields results comparable to Test Method D1107.
SCOPE
1.1 This test method covers the determination of ethanol soluble extractives, expressed as a percentage of the oven-dried biomass, of hard and soft woods, herbaceous materials (such as switchgrass and sericea), agricultural residues (such as corn stover, wheat straw, and bagasse), and wastepaper (such as office waste, boxboard, and newsprint). All results are reported relative to the oven-dried weight of the sample.
Note 1: This test method may not be suitable for hard and soft wood samples that include bark or those with more than 10% extractable materials.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2021
• ICS: 65.040.20 - Buildings and installations for processing and storage of agricultural produce
• Technical Committee: E48 - Bioenergy and Industrial Chemicals from Biomass
• Drafting Committee: E48.05 - Biomass Conversion

Relations

• Refers: ASTM E1756-08(2020) - Standard Test Method for Determination of Total Solids in Biomass
• Effective Date: 01-Jul-2020
• Refers: ASTM E1757-19 - Standard Practice for Preparation of Biomass for Compositional Analysis
• Effective Date: 01-Apr-2019
• Refers: ASTM E1757-01(2015) - Standard Practice for Preparation of Biomass for Compositional Analysis
• Effective Date: 01-Jun-2015
• Refers: ASTM E1756-08(2015) - Standard Test Method for Determination of Total Solids in Biomass
• Effective Date: 01-Jun-2015
• Refers: ASTM E1756-08 - Standard Test Method for Determination of Total Solids in Biomass
• Effective Date: 01-May-2008
• Refers: ASTM E1757-01(2007) - Standard Practice for Preparation of Biomass for Compositional Analysis
• Effective Date: 15-Nov-2007
• Refers: ASTM D1107-96(2007) - Standard Test Method for Ethanol-Toluene Solubility of Wood
• Effective Date: 01-Apr-2007
• Refers: ASTM E1756-95 - Standard Test Method for Determination of Total Solids in Biomass
• Effective Date: 10-Nov-2001
• Refers: ASTM E1757-01 - Standard Practice for Preparation of Biomass for Compositional Analysis
• Effective Date: 10-Nov-2001
• Refers: ASTM E1757-95 - Standard Practice for Preparation of Biomass for Compositional Analysis
• Effective Date: 10-Nov-2001
• Refers: ASTM E1756-01 - Standard Test Method for Determination of Total Solids in Biomass
• Effective Date: 10-Nov-2001
• Refers: ASTM D1107-96(2001) - Standard Test Method for Ethanol-Toluene Solubility of Wood
• Effective Date: 10-Sep-2001
• Refers: ASTM D1107-96 - Standard Test Method for Ethanol-Toluene Solubility of Wood
• Effective Date: 10-Sep-1996

Overview

ASTM E1690-08(2021), Standard Test Method for Determination of Ethanol Extractives in Biomass, defines a systematic procedure for quantifying ethanol-soluble extractives in various biomass materials. Developed by ASTM International, this method is specifically designed for hard and soft woods, herbaceous plant materials, agricultural residues, and wastepaper. Results are reported as a percentage of the oven-dried biomass weight, ensuring consistency and comparability in biomass compositional analysis.

Ethanol extractives include materials in biomass that dissolve in ethanol, such as waxes, fats, resins, tannins, gums, sugars, starches, and pigments. These nonstructural components are critical to identify and remove before further chemical analysis since they are not part of the biomass's primary structure and may interfere with subsequent testing.

Key Topics

• Purpose: To determine the amount of nonstructural, ethanol-soluble substances within a biomass sample, facilitating accurate analysis of structural components.
• Applicable Materials:
  • Hardwoods and softwoods (excluding bark-laden or highly extractive wood)
  • Herbaceous materials (e.g., switchgrass, sericea)
  • Agricultural residues (e.g., corn stover, wheat straw, bagasse)
  • Wastepaper (e.g., office waste, boxboard, newsprint)
• Principle of the Method:
  • Biomass samples are dried, weighed, and extracted using ethanol in a Soxhlet apparatus.
  • The extraction yields soluble materials which are quantified post-evaporation.
  • Results are calculated and reported as a percentage of the sample’s oven-dried weight.
• Units: All measurements are reported using SI units.
• Relationship to Other Standards: Results are consistent with those from ASTM D1107, another recognized method for determining extractives in wood.

Applications

The ASTM E1690 test method is essential across multiple industries and research fields where understanding the composition of biomass is critical:

• Bioenergy Production: Removes nonstructural substances before analyzing lignin, cellulose, or hemicellulose, providing accurate feedstock characterization for biofuels and bio-based chemicals.
• Pulp and Paper Industry: Assesses and controls extractive content in raw materials to optimize pulping processes and improve paper quality.
• Agricultural and Environmental Research: Supports the study of crop residues and waste management by accounting for nonstructural biomass constituents.
• Quality Control: Offers reliable data for evaluating material consistency in industrial and environmental laboratories.
• Product Development: Enables the identification of valuable extractable byproducts such as natural waxes, pigments, or resins from biomass processing.

Related Standards

To ensure comprehensive biomass analysis and align with international best practices, consider these related ASTM standards:

• ASTM D1107: Standard Test Method for Ethanol-Toluene Solubility of Wood - Provides results comparable to E1690 but uses a different solvent mix.
• ASTM E1756: Standard Test Method for Determination of Total Solids in Biomass - Used to determine oven-dried weight for more accurate extractive calculation.
• ASTM E1757: Practice for Preparation of Biomass for Compositional Analysis - Ensures consistent sample preparation prior to analysis.

Practical Value

By following ASTM E1690-08(2021), laboratories and industrial users can accurately assess ethanol extractives content in a wide range of biomass resources. This standardized methodology improves data consistency, guides process optimization, and supports regulatory compliance in bioenergy, paper production, environmental science, and waste management sectors.

Keywords: ethanol extractives, biomass analysis, Soxhlet extraction, agricultural residue, herbaceous materials, waste paper, bioenergy, ASTM standards, nonstructural components, biofuel feedstock characterization.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1690 − 08 (Reapproved 2021)
Standard Test Method for
Determination of Ethanol Extractives in Biomass
This standard is issued under the fixed designation E1690; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the determination of ethanol 3.1 Definitions:
solubleextractives,expressedasapercentageoftheoven-dried 3.1.1 ethanol extractives—the residue remaining after
biomass,ofhardandsoftwoods,herbaceousmaterials(suchas evaporation of the ethanol solvent.These are materials that are
switchgrass and sericea), agricultural residues (such as corn removed from the biomass by extraction with 190 proof
stover, wheat straw, and bagasse), and wastepaper (such as ethanol.
office waste, boxboard, and newsprint).All results are reported
3.1.2 oven-dried weight—the moisture-free corrected
relative to the oven-dried weight of the sample.
weight of the prepared biomass sample. The correction factor
is determined in accordance with Test Method E1756.
NOTE 1—This test method may not be suitable for hard and soft wood
samples that include bark or those with more than 10% extractable
3.1.3 prepared biomass—the biomass that has been pre-
materials.
pared in accordance with Practice E1757.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 4. Significance and Use
standard.
4.1 Ethanol extractives are any materials found in biomass
1.3 This standard does not purport to address all of the
that are soluble in ethanol. They are not considered to be part
safety concerns, if any, associated with its use. It is the
of the structural components of biomass and should be re-
responsibility of the user of this standard to establish appro-
moved prior to any chemical analysis of the sample. The
priate safety, health, and environmental practices and deter-
prolonged extraction removes nonstructural materials that can
mine the applicability of regulatory limitations prior to use.
includewaxes,fats,resins,tannins,gums,sugars,starches,and
1.4 This international standard was developed in accor-
pigments. Removing hydrophobic materials from the biomass
dance with internationally recognized principles on standard-
makesiteasiertowetthematerialfortheanalysisofstructural
ization established in the Decision on Principles for the
components in the biomass.
Development of International Standards, Guides and Recom-
4.2 This test method yields results comparable to Test
mendations issued by the World Trade Organization Technical
Method D1107.
Barriers to Trade (TBT) Committee.
5. Apparatus
2. Referenced Documents
5.1 Soxhlet Extraction Apparatus, glass, of a size (100 mL)
2.1 ASTM Standards:
suitable for containing the sample and a 250-mL collection
,
D1107TestMethodforEthanol-TolueneSolubilityofWood
flask.
E1756Test Method for Determination of Total Solids in
5.2 Alundum Extraction Thimbles, medium porosity (10 to
Biomass
15-µm pore), sized to fit the Soxhlet extractor.
E1757Practice for Preparation of Biomass for Composi-
tional Analysis
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 receiving
This test method is under the jurisdiction of ASTM Committee E48 on
vessel. A water aspirator will generally provide sufficient
BioenergyandIndustrialChemicalsfromBiomassandisthedirectresponsibilityof
vacuum (<150 torr).
Subcommittee E48.05 on Biomass Conversion.
Current edition approved Oct. 1, 2021. Published November 2021. Originally
5.5 Vacuum Oven, controllable to 40 6 1°C and with
approved in 1995. Last previous edition approved in 2016 as E1690–08(2016).
vacuum between 75 and 100 torr.
DOI: 10.1520/E1690-08R21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6. Reagents and Materials
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.1 Ethyl Alcohol, 190 proof, USP grade.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1690 − 08 (2021)
7. Sampling 9. Calculation
7.1 The sample is milled material prepared in accordance 9.1 Calculate the weight of oven-dried biomass used for the
with Practice E1757. extraction:
W 5 W 2 W 3 T/100% (1)
~ ! ~ !
s st t
8. Procedure
where:
8.1 Dry the Soxhlet extraction thimble in a drying oven at
W = weight of moisture-free solids in the prepared sample,
105°C overnight. Remove it and allow it to cool to room
s
g,
temperature in a desiccator.
W = weight of sample and thimble (8.2), g,
st
8.2 Weigh the Soxhlet extraction thimble to the nearest 0.1
W = tare weight of thimble (8.2), g, and
t
mg, and record the weight
...