Compared to the woody biomass lignin quantitation in grasses is more involved due to their higher protein content. For instance, the acid hydrolysis based methods of lignin determination (e.g., Klason method) need to be modified. However, recently a novel approach based on FT-Raman spectroscopy was developed [U.P. Agarwal, Proceedings 16th ISWFPC, Tianjin, pp. 170(2011)] that successfully quantified lignin in various biomass materials - woods, wood pulps, and corn stalk. The Raman method used the strategy to chemically modify lignin, without removing it, such that at 1600 cm-1 the spectral contributions of chromophores and aromatic-ring conjugated lignin units were minimized. In the present study, the concentration of grass lignin was determined using the same approach but the already developed calibration equation between Klason/total lignin and (1600/1096)corr for the non-grass materials was used. Using the (1600/1096)corr Raman ratios for the grasses and the calibration equation, the Klason/total lignin concentrations were estimated. Use of the calibration that did not incorporate the Klason/total lignin data for the grasses was justified considering that for these materials such data cannot be reliably obtained. Based on earlier and current successes of the FT-Raman  method in quantifying lignin it appears that the method has the potential for being used for routine analysis.

Quantitation of lignin in grasses by near-IR FT-Raman spectroscopy

243rd National Meeting (2012)

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