skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

This content will become publicly available on March 27, 2020

Title: Estimation of Syringyl Units in Wood Lignins by FT-Raman Spectroscopy

Abstract

Syringyl (S) lignin content and the syringyl-to-guaiacyl (S/G) lignin ratio are important characteristics of wood and lignocellulosic biomass. While numerous methods are available for estimating S lignin units and the S/G ratio, in this work, a new method based on Raman spectroscopy that uses the 370 cm –1 Raman band-area intensity (370-area) was developed. The reliability of the Raman method for determining S content was first tested by the quantitative analysis of three syringyl lignin models by sampling them, separately, in dioxane and in Avicel. Good linear correlations between the 370 cm –1 intensity and model concentrations were obtained. Next, the percent syringyl (%S) lignin units in various woods were measured by correlating the 370 cm –1 Raman intensity data with values of S units in lignin determined by three regularly used methods, namely, thioacidolysis, DFRC, and 2D-HSQC NMR. The former two methods take into account only the monomers cleaved from β–O–4-linked lignin units, whereas the NMR method reports S content on the whole cell wall lignin. When the 370-area intensities and %S values from the regularly used methods were correlated, good linear correlations were obtained (R 2 = 0.767, 0.731, and 0.804, respectively, for the three methods). The correlationmore » with the highest R 2, i.e., with the 2D NMR approach, is introduced for estimating S units in wood lignins by Raman spectroscopy as, in principle, both represent the whole cell wall lignin and not just the portion of lignin that gets cleaved to release monomers. The Raman analysis method is quick, uses minimal harmful chemicals, is carried out nondestructively, and is insensitive to the wet or dry state of the sample. The only limitations are that the sample of wood contains at least 30% S and not be significantly fluorescent, although the latter can be mitigated in some cases.« less

Authors:
ORCiD logo [1];  [1];  [2];  [2];  [3]
  1. US Dept. of Agriculture (USDA), Madison, WI (United States)
  2. Univ. of Wisconsin-Madison, Madison, WI (United States)
  3. Michigan State Univ., East Lansing, MI (United States)
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1546618
Grant/Contract Number:  
SC0018409; FC02-07ER64494
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Agricultural and Food Chemistry
Additional Journal Information:
Journal Volume: 67; Journal Issue: 15; Journal ID: ISSN 0021-8561
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Cell wall; DFRC; NMR; syringyl-to-guaiacyl lignin ratio; percent syringyl; thioacidolysis

Citation Formats

Agarwal, Umesh P., Ralph, Sally A., Padmakshan, Dharshana, Liu, Sarah, and Foster, Cliff E. Estimation of Syringyl Units in Wood Lignins by FT-Raman Spectroscopy. United States: N. p., 2019. Web. doi:10.1021/acs.jafc.8b06707.
Agarwal, Umesh P., Ralph, Sally A., Padmakshan, Dharshana, Liu, Sarah, & Foster, Cliff E. Estimation of Syringyl Units in Wood Lignins by FT-Raman Spectroscopy. United States. doi:10.1021/acs.jafc.8b06707.
Agarwal, Umesh P., Ralph, Sally A., Padmakshan, Dharshana, Liu, Sarah, and Foster, Cliff E. Wed . "Estimation of Syringyl Units in Wood Lignins by FT-Raman Spectroscopy". United States. doi:10.1021/acs.jafc.8b06707.
@article{osti_1546618,
title = {Estimation of Syringyl Units in Wood Lignins by FT-Raman Spectroscopy},
author = {Agarwal, Umesh P. and Ralph, Sally A. and Padmakshan, Dharshana and Liu, Sarah and Foster, Cliff E.},
abstractNote = {Syringyl (S) lignin content and the syringyl-to-guaiacyl (S/G) lignin ratio are important characteristics of wood and lignocellulosic biomass. While numerous methods are available for estimating S lignin units and the S/G ratio, in this work, a new method based on Raman spectroscopy that uses the 370 cm–1 Raman band-area intensity (370-area) was developed. The reliability of the Raman method for determining S content was first tested by the quantitative analysis of three syringyl lignin models by sampling them, separately, in dioxane and in Avicel. Good linear correlations between the 370 cm–1 intensity and model concentrations were obtained. Next, the percent syringyl (%S) lignin units in various woods were measured by correlating the 370 cm–1 Raman intensity data with values of S units in lignin determined by three regularly used methods, namely, thioacidolysis, DFRC, and 2D-HSQC NMR. The former two methods take into account only the monomers cleaved from β–O–4-linked lignin units, whereas the NMR method reports S content on the whole cell wall lignin. When the 370-area intensities and %S values from the regularly used methods were correlated, good linear correlations were obtained (R2 = 0.767, 0.731, and 0.804, respectively, for the three methods). The correlation with the highest R2, i.e., with the 2D NMR approach, is introduced for estimating S units in wood lignins by Raman spectroscopy as, in principle, both represent the whole cell wall lignin and not just the portion of lignin that gets cleaved to release monomers. The Raman analysis method is quick, uses minimal harmful chemicals, is carried out nondestructively, and is insensitive to the wet or dry state of the sample. The only limitations are that the sample of wood contains at least 30% S and not be significantly fluorescent, although the latter can be mitigated in some cases.},
doi = {10.1021/acs.jafc.8b06707},
journal = {Journal of Agricultural and Food Chemistry},
number = 15,
volume = 67,
place = {United States},
year = {2019},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on March 27, 2020
Publisher's Version of Record

Save / Share: