Qualitative heteronuclear single quantum coherence (HSQC) NMR techniques, requiring relatively short experimental time with high sensitivity and resolution has become one of the most important tools to study lignocellulosics and lignins in particular (Liitia et al., 2003, Mansfield et al., 2012). Moreover, for lignin characterization, HSQC over the past years has greatly benefitted from both the advancements in NMR technologies as such, and from the improved assignment of NMR resonances based on numerous model experiments and comparative lignin studies (Constant et al. 2016, Ralph et al. 2010).
The method provides comprehensive data on structure, i.e. functional groups, chains, the most important lignin interunit bonding motifs, such as β-O-4, β-5, β–β and others, as well as information on its purity, e.g. presence of carbohydrates or extractive substances.
The analysis is conducted on Bruker Avance II 400 spectrometer.
Sample amount required: 50-100 mg.
Constant, S., Wienk, H. L. J., Frissen, A. E., de Peinder, P., Boelens, R., van Es, D. S., Grisel, R. J. H., Weckhuysen, B. M., Huijgen, W. J. J., Gosselink, R. J. A., Bruijnincx, P. C. A. (2016).
New insights into the structure and composition of technical lignins: a comparative characterisation study.
Green Chemistry, 18(9), 2651-2665. doi: 10.1039/c5gc03043a
Liitia, T. M., Maunu, S. L., Hortling, B., Toikka, M., & Kilpelainen, I. (2003).
Analysis of technical lignins by two- and three-dimensional NMR spectroscopy.
Journal of Agricultural and Food Chemistry, 51(8), 2136-2143. doi: 10.1021/jf0204349
Mansfield, S. D., Kim, H., Lu, F. C., & Ralph, J. (2012).
Whole plant cell wall characterization using solution-state 2D NMR.
Nature Protocols, 7(9), 1579-1589. doi: 10.1038/nprot.2012.064
Ralph, J., Landucci, L. L. (2010).
NMR of Lignins. in Lignin and Lignans;
Advances in Chemistry, eds. C. Heitner, D. R. Dimmel and J. A. Schmidt, CRC Press (Taylor & Francis Group), Boca Raton, FL, 137-234. doi.org/10.1201/EBK1574444865