ASTM D1106-21

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Designation: D1106 − 96 (Reapproved 2013) D1106 − 21 Technical Association of Pulp and Paper Industry
Standard Method T 222-om-83
Standard Test Method for
1,2
Acid-Insoluble Lignin in Wood
This standard is issued under the fixed designation D1106; 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.
1. Scope
1.1 This test method covers the determination of the acid-insoluble lignin content of wood.
1.2 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precautionary statements are given in 6.1.
1.3 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.
2. Referenced Documents
2.1 ASTM Standards:
D1107 Test Method for Ethanol-Toluene Solubility of Wood
3. Principle of Method
3.1 When wood is treated with strong acids the carbohydrates are hydrolyzed, leaving an insoluble residue which is determined
as acid-insoluble lignin. Since some of the wood extractives (oils, resins, fats, waxes, tannins, gums, and starch) would remain
insoluble with the lignin, these are first removed by proper extraction with suitable solvents. The 72 % sulfuric acid method for
lignin contains two and sometimes three preliminary extractive treatments, treatments of the wood, namely: (1) with
alcohol,ethanol, to remove the catechol tannins; (2) with alcohol-benzeneethanol-toluene solution, to remove the resins, oils, fats
and waxes; and (3) with hot water, to remove the remaining water-soluble materials.
3.2 The alcoholethanol extraction is necessary in analysis of woods high in tannin; that is, oak, chestnut, redwood, etc. It has not
been shown necessary in the more common pulpwoods, such as the various species of spruce, pine, fir, hemlock, poplar, birch,
beech, and maple. It is recommended that for these woods the alcohol extraction be omitted unless it is desirable for a special
This test method is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.01 on Fundamental Test Methods
and Properties.
Current edition approved Aug. 1, 2013Feb. 1, 2021. Published September 2013March 2021. Originally approved in 1950. Last previous edition approved in 20072013
as D1106 – 96 (2007).(2013). DOI: 10.1520/D1106-96R13.10.1520/D1106-21.
This standard was originally based upon TAPPI standard Method T222-om-83, which has been replaced by T 222 om-15.
For further information on this test method the following references may be consulted:
Bray, M. W., “Methods Used at the Forest Products Laboratory for the Chemical Analysis of Pulps and Pulpwoods,” Paper Trade Journal, Vol 87, No. 25, December 20,
1928, p. 29.
Ritter, G. J., Seborg, R. M., Mitchell, R. L., Industrial and Engineering Chemistry, Analytical Edition, Vol 4, 1932, p. 202.
Ritter, G. J., and Barbour, J. H., Industrial and Engineering Chemistry, Analytical Edition, Vol 7, 1935, p. 238.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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D1106 − 21
purpose. In analysis of woods not listed, the desirability of the alcohol extraction depends upon the purpose of the analysis and
the report should state whether or not alcoholethanol extraction was used.
4. Significance and Use
4.1 Wood contains approximately 20 to 30 % lignin. Removal of the lignin is the primary objective of pulping and bleaching
procedures. Determination of the lignin content provides information for the evaluation and application of these processes.
5. Apparatus
5.1 Extraction Apparatus—A compact form of Soxhlet extraction apparatus, with ground-glass joints, is preferable. The apparatus
shall consist of the following items:
5.1.1 Soxhlet Extraction Flask, having a capacity of 250 mL.
5.1.2 Soxhlet Extraction Tube, 45 to 50 mm in inside diameter, having a capacity to the top of the siphon of approximately 100
mL and a siphon tube approximately 55 mm in height. Extraction tubes of these dimensions siphon more rapidly than extractors
with higher siphon tubes.
5.1.3 Condenser, of the Hopkins inner-cooled type.
5.1.4 Extraction Crucibles, of Alundum or fritted glass and of medium or fine porosity.
5.2 Filtering Crucibles—Alundum, porous porcelain, or fritted-glass crucibles (all of fine porosity), or Gooch crucibles with a
glass-fiber mat, are recommended for filtering the separated lignin. Glass crucibles cannot be used if the lignin is to be ashed.
6. Reagents
6.1 Ethylene-TolueneEthanol-Toluene Solution—Mix 1.0 L absolute ethanol and 427 mL toluene. (Warning—Avoid inhalation of
vapors and contact with skin.)
6.2 Sulfuric Acid (72 %)—Carefully pour 665 mL of
H SO (sp gr 1.84) into about 300 mL
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