ASTM E1721-01(2009)
(Test Method)Standard Test Method for Determination of Acid-Insoluble Residue in Biomass
Standard Test Method for Determination of Acid-Insoluble Residue in Biomass
SIGNIFICANCE AND USE
The acid-insoluble residue content is used in conjunction with other assays to determine the total composition of biomass samples.
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 105°C 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 standard. No other units of measurement are included in this 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)
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Designation: E1721 − 01(Reapproved 2009)
Standard Test Method for
Determination of Acid-Insoluble Residue in Biomass
This standard is issued under the fixed designation E1721; 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 (´) 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers determination of the acid-
E1690 Test Method for Determination of Ethanol Extrac-
insoluble residue of hard and soft woods, herbaceous materials
tives in Biomass
(suchasswitchgrassandsericea),agriculturalresidues(suchas
E1756 Test Method for Determination of Total Solids in
corn stover, wheat straw, and bagasse), wastepaper (such as
Biomass
office waste, boxboard, and newsprint), acid and alkaline
E1757 Practice for Preparation of Biomass for Composi-
pretreated biomass, and the solid fraction of fermentation
tional Analysis
residues. All results are reported relative to the 105°C oven-
dried weight of the sample.
3. Terminology
1.2 The residue collected contains the acid-insoluble lignin
3.1 Definitions:
and any condensed proteins from the original sample. An
3.1.1 acid-insoluble residue—the solid residue, corrected
independent nitrogen analysis would be required to determine
for acid-insoluble ash, retained on a medium-porosity filter
the acid-insoluble lignin content separate from the condensed
crucible after the primary 72 % and secondary 4 % H SO
protein fraction and is outside the scope of this test method.
2 4
hydrolysis described in this test method. This material is
1.3 A portion of the lignin in some biomass samples will
primarily acid-insoluble lignin and any condensed proteins.
remain soluble during this procedure. The total lignin in a
3.1.2 prepared biomass—material that has been treated in
biomass sample includes both acid-soluble lignin and lignin in
accordancewithPracticeE1757inordertoraisethetotalsolids
the acid insoluble residue.
content above 85 %, based on an oven-dried solids weight.
1.4 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 The acid-insoluble residue content is used in conjunc-
1.5 This standard does not purport to address all of the
tion with other assays to determine the total composition of
safety concerns, if any, associated with its use. It is the
biomass samples.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Interferences
bility of regulatory limitations prior to use. Specific hazards
5.1 The results of acid-insoluble residue analysis are af-
statements are given in Section 8 and Note 2 and Note 4.
fected by the incomplete hydrolysis of biomass. The results
willbebiasedhighunlessthesampleishydrolyzedcompletely.
This test method is under the jurisdiction of ASTM Committee E48 on
Bioenergy and Industrial Chemicals from Biomass and is the direct responsibility of
Subcommittee E48.05 on Biomass Conversion. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2009. Published March 2010. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
appproved in 1995. Last previous edition approved in 2001 asE1721-01. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E1721-01R09. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1721 − 01 (2009)
Take care to mix the acid/biomass slurry thoroughly during the duce an error in the calculation because ground biomass can
concentrated acid hydrolysis. gain or lose moisture rapidly when exposed to the atmosphere.
5.2 The results of acid-insoluble residue analysis are af-
10. Procedure
fected by the timing of the acid digestion steps. The insoluble
10.1 Label the crucibles needed for analysis individually,
residue will dissolve slowly into solution in an irreproducible
and ignite them at 575 6 25°C to achieve a constant weight of
fashion. The timing within this test method must be followed
60.3 mg. Store the ignited crucibles in a desiccator until
closely.
needed.
6. Apparatus
NOTE 1—In order to determine the absolute amounts of acid-insoluble
residue and acid-insoluble ash, for quality control purposes, it is useful to
6.1 Analytical Balance, readable to 0.1 mg.
weigh and record the ignited crucible to the nearest 0.1 mg.
6.2 Convection Oven, with a temperature control of 105 6
10.2 Weigha0.3 60.01-gsampletothenearest0.1mg,and
3°C.
place it in a test tube. Record the initial weight as W .
6.3 Muffle Furnace—An electric furnace is recommended
NOTE 2—Warning: 72 % sulfuric acid is very corrosive and should be
for igniting the sample. The furnace should be fitted with an
handled only by trained personnel.
indicating pyrometer or thermocouple so that the required
10.3 Add 3.00 6 0.01 mL (4.92 6 0.01 g) of 72 % H SO ,
2 4
temperature of 575 6 25°C can be maintained.
and stir for 1 min or until mixed thoroughly.
6.4 Autoclave, capable of maintaining 121 6 3°C.
10.4 Place the test tube in the water bath controlled to 30 6
6.5 Water Bath, set at 30 6 1°C.
1°C, and hydrolyze for 2 h.
6.6 Desiccator, using anhydrous calcium sulfate.
NOTE 3—The hydrolysis time may be reduced to1hifthe dried sample
has been milled and sieved to pass through a 20-mesh sieve and be
7. Reagents and Materials retained on a 80-mesh sieve.
10.5 Stir the sample every 15 min to ensure complete
7.1 Chemicals:
7.1.1 72 % H SO , specific gravity 1.6389 6 0.0012 at mixing and wetting.
2 4
15.6°C/15.6°C or 12.00 6 0.02 M.
10.6 Transfer the hydrolyzate to a glass bottle, and dilute to
7.1.2 Water, 18 MΩ deionized.
a 4 % acid
...
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