Fig. 3From: Microbial biogas production from hydrolysis lignin: insight into lignin structural changesThe 2D HSQC NMR spectral regions of interest (aromatic region) for birch samples and the structures of main lignin units (S, G, and H). Numbers indicate carbon atoms in the aromatic ring. For well-resolved correlation peaks, contours are color coded to match their structures shownBack to article page