Figure 3. Enlarged view of ¹H HR-MAS NMR spectra shown in Fig. 2.

Ancient samples A1 (red line), B1 (brown line) and A3 (dark green line) (panel A); modern samples P2 (black line), P2C9024 (grey line) and P2C9048 (light green line) (Panel B); acetic acid (black line), hexanoic acid (dark green line), pyruvic acid (cyan line) and sebacic acid (dark pink line) ¹H HR-MAS NMR spectra in D₂O, from²⁸, are plotted for comparison at the bottom of both panels.