*2.3. NMR*

Despite the fact that the sample aliquot was so small (the amount of LSD in a blotter is usually in the range 30–100 μg), the 1H-NMR spectrum revealed a complex mixture (Figure 5) in which many signals could be identified as typical of LSD-like substances, and which share the same backbone structure. Nevertheless, the most noteworthy signals were those which allowed the identification of 1B-LSD in this mixture, i.e., those assigned to the butyl (CH3 and CH2) part of the molecule. On the other hand, a direct 1D 13C NMR measurement was not possible due to the reduced quantity of the sample and the presence of relatively large quantities of other interfering substances extracted

from the original matrix. The bond connection between the butyl proton resonances was confirmed with the 2D DQF-COSY experiment (Figure S4). The 2D HSQC confirmed the presence of the methyl and methylene groups and HMBC showed the connection of the methylene groups with a signal of a quaternary carbon at 171.6 ppm in line with the C=O reported by Brandt et al. [9]. All our NMR results are consistent with those for 1B-LSD as reported by Brandt et al. [9].

**Figure 5.** 1H NMR spectrum 1B-LSD (**a**) full spectrum, (**b**) expansion of the aromatic region (**c**) expansion of the aliphatic region showing the region of interest for the identification of the 1-butyl group. The peaks labelled with \* at 3.1 and 3.4 ppm correspond to the 13C satellite signals of the residual protonated NMR solvent (methanol-d4 ≥ 99.8 atom % D).
