ASTM E1721-95
(Test Method)Standard Test Method for Determination of Acid-Insoluble Residue in Biomass
Standard Test Method for Determination of Acid-Insoluble Residue in Biomass
SCOPE
1.1 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 as corn stover, wheat straw, and bagasse), wastepaper (such as office waste, boxboard, and newsprint), acid and alkaline pretreated biomass, and the solid fraction of fermentation residues. All results are reported relative to the 105C oven-dried weight of the sample.
1.2 The residue collected contains the acid-insoluble lignin and any condensed proteins from the original sample. An independent nitrogen analysis would be required to determine the acid-insoluble lignin content separate from the condensed protein fraction and is outside the scope of this test method.
1.3 A portion of the lignin in some biomass samples will remain soluble during this procedure. The total lignin in a biomass sample includes both acid-soluble lignin and lignin in the acid insoluble residue.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 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 and health practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 8 and Note 2 and Note 4.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: E 1721 – 95
Standard Test Method for
Determination of Acid-Insoluble Residue in Biomass
This standard is issued under the fixed designation E 1721; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Biomass is composed largely of the following: cellulose, a polymer of glucose; hemicellulose, a
complex polymer, the main chain of which consists of xylans or glucomannans; and lignin, a complex
phenolic polymer. The lignin is mostly insoluble in mineral acids, unlike the other cell wall
components of biomass. For this reason, lignin can be analyzed gravimetrically after hydrolyzing the
cellulose and hemicellulose fractions with sulfuric acid.
1. Scope 3. Terminology
1.1 This test method covers determination of the acid- 3.1 Definitions:
insoluble residue of hard and soft woods, herbaceous materials 3.1.1 acid-insoluble residue—the solid residue, corrected
(such as switchgrass and sericea), agricultural residues (such as for acid-insoluble ash, retained on a medium-porosity filter
corn stover, wheat straw, and bagasse), wastepaper (such as crucible after the primary 72 % and secondary 4 % H SO
2 4
office waste, boxboard, and newsprint), acid and alkaline hydrolysis described in this test method. This material is
pretreated biomass, and the solid fraction of fermentation primarily acid-insoluble lignin and any condensed proteins.
residues. All results are reported relative to the 105°C oven- 3.1.2 prepared biomass—material that has been treated in
dried weight of the sample. accordance with Practice E 1757 in order to raise the total
1.2 The residue collected contains the acid-insoluble lignin solids content above 85 %, based on an oven-dried solids
and any condensed proteins from the original sample. An weight.
independent nitrogen analysis would be required to determine
4. Significance and Use
the acid-insoluble lignin content separate from the condensed
protein fraction and is outside the scope of this test method. 4.1 The acid-insoluble residue content is used in conjunc-
tion with other assays to determine the total composition of
1.3 The values stated in SI units are to be regarded as the
standard. biomass samples.
1.4 This standard does not purport to address all of the
5. Interferences
safety concerns, if any, associated with its use. It is the
5.1 The results of acid-insoluble residue analysis are af-
responsibility of the user of this standard to establish appro-
fected by the incomplete hydrolysis of biomass. The results
priate safety and health practices and determine the applica-
will be biased high unless the sample is hydrolyzed completely.
bility of regulatory limitations prior to use. Specific hazards
Take care to mix the acid/biomass slurry thoroughly during the
statements are given in Section 8 and Note 2 and Note 4.
concentrated acid hydrolysis.
2. Referenced Documents
5.2 The results of acid-insoluble residue analysis are af-
2.1 ASTM Standards: fected by the timing of the acid digestion steps. The insoluble
residue will dissolve slowly into solution in an irreproducible
E 1690 Test Method for Determination of Ethanol Extrac-
tives in Biomass fashion. The timing within this test method must be followed
closely.
E 1756 Test Method for Determination of Total Solids in
Biomass
6. Apparatus
E 1757 Practice for Preparation of Biomass for Composi-
6.1 Analytical Balance, readable to 0.1 mg.
tional Analysis
6.2 Convection Oven, with a temperature control of 105 6
3°C.
This test method is under the jurisdiction of ASTM Committee E-48 on
6.3 Muffle Furnace—An electric furnace is recommended
Biotechnology and is the direct responsibility of Subcommittee E48.05 on Biomass
for igniting the sample. The furnace should be fitted with an
Conversion.
indicating pyrometer or thermocouple so that the required
Current edition approved Sept. 10, 1995. Published November 1995.
Annual Book of ASTM Standards, Vol 11.05.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 1721
NOTE 3—The hydrolysis time may be reduced to1hifthe dried sample
temperature of 575 6 25°C can be maintained.
has been milled and sieved to pass through a 20-mesh sieve and be
6.4 Autoclave, capable of maintaining 121 6 3°C.
retained on a 80-mesh sieve.
6.5 Water Bath, set at 30 6 1°C.
6.6 Desiccator, using anhydrous calcium sulfate.
10.5 Stir the sample every 15 min to ensure complete
mixing and wetting.
7. Reagents and Materials
10.6 Transfer the hydrolyzate to a glass bottle, and dilute to
7.1 Chemicals:
a 4 % acid concentration by adding 84.00 6 0.04 mL water or
7.1.1 72 % H SO , specific gravity 1.6389 6 0.0012 at
2 4
by bringing the combined weight of sample, acid, and water up
15.6°C/15.6°C or 12.00 6 0.02 M.
to 89.22 6 0.04 g. Be careful to transfer all of the residual
7.1.2 Water,18MV deionized.
solids along with the hydrolysis liquor.
7.2 Materials:
10.7 Stopper each of the bottles, and crimp the aluminum
7.2.1 Glass Serum Bottles, 125 mL, crimp top style, with
seals into place.
rubber stoppers and aluminum seals to fit.
10.8 Set the autoclave to a liquid vent cycle to prevent loss
7.2.2 Glass Filtering Crucible, 50 mL, medium porosity,
of sample from the bottle in the event of a loose crimp seal.
with a nominal maximum pore size of 10 μm.
Autoclave the samples in their sealed bottles for1hat121 6
7.2.3 Vacuum Adapter for Crucibles.
3°C.
8. Hazards
NOTE 4—Warning: Handle sealed bottles with caution after the auto-
clave step since they may become pressurized.
8.1 Handle the sulfuric acid carefully.
8.2 Use caution when handling glass bottles after the
10.9 After completion of the autoclave cycle, allow the
autoclave step since they may become pressurized.
samples to cool for approximately 20 min at room temperature
before removing the seals and stoppers.
9. Sampling, Test Specimens, and Test Units
10.10 Vacuum filter the hydrolysis solution thr
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