Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Umesh P. AgarwalSally A. Ralph; Dharshana Padmakshan; Sarah Liu; Cliff E. Foster
    Date: 2019
    Source: Journal of Agricultural and Food Chemistry. 67(15): 4367-4374.
    Publication Series: Scientific Journal (JRNL)
    Station: Forest Products Laboratory
    PDF: Download Publication  (1.0 MB)


    Syringyl (S) lignin content and the syringyl-to-guaiacyl (S/G) lignin ratio are important characteristics of wood and lignocellulosic biomass. Although 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 approach 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 method, is proposed 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.

    Publication Notes

    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Agarwal, Umesh P.; Ralph, Sally A.; Padmakshan, Dharshana; Liu, Sarah; Foster, Cliff E. 2019. Estimation of syringyl units in wood lignins by FT-Raman spectroscopy. Journal of Agricultural and Food Chemistry. 67(15): 4367-4374.


    Google Scholar


    Cell wall, DFRC, NMR, syringyl-to-guaiacyl lignin ratio, percent syringyl, thioacydolysis

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page