Surface enhanced Raman spectroscopy for lignin analysis

Abstract

Near-IR surface enhanced Raman scattering (SERS) spectra of spruce Wiley milled-wood (WMW) and milled-wood lignin (MWL) adsorbed on the silver nano and micro-particles were obtained recently in our laboratory. When the SERS spectra of wood and MWL were compared they were found to be almost identical which suggested that the signals from the carbohydrate components were absent in the WMW SERS spectrum. This was also supported by the fact that no SERS spectrum of cellulose could be obtained under these conditions. Therefore, lignin could be selectively studied in the presence of other wood constituents without separation. Some general characteristics of the lignin SERS spectrum are described. The SERS technique was also found to be highly sensitive because only a very small amount of the sample is needed. For MWL, SERS and normal Raman spectra were compared and it was determined that significant spectral changes were present. Raman spectral changes and x-ray photoelectron spectral analysis of the MWL SERS sample provided evidence that showed that lignin is strongly adsorbed on silver. This nano- and micro-particle based lignin analysis technique is expected to make a significant contribution to investigating lignin in various lignocellulosic materials.

Citation

Agarwal, U.P.; Reiner, R.S.; Beecher, J.F. 2009. Surface enhanced raman spectroscopy for lignin analysis. In: Proceedings of 15th international symposium on wood, fiber and pulping chemistry. 2009 June 15-18; Oslo, Norway: Congress-Conference AS, www.congrex.no. O-003, 4 p., limited availability.