For this proof-of-concept, the experimental IRIS spectrum of [DOPAC-H] -is again taken as the hypothetical unknown. Figure presents the nine highest-ranked entries upon matching this IRIS spectrum against the entire library, without constraint on chemical formula. The fact that DOPAC itself is ranked #1 out of 2707 deprotonated entries demonstrates both the uniqueness of the experimental IR spectrum, as well as its accurate prediction by DFT calculations. Inspecting the compounds ranked #2 -#9 reveals the potential for de novo structural elucidation via this unsupervised search: the top-9 metabolites are structurally very similar to DOPAC, mostly differing in the length of the alkyl chain, the addition of a methyl or hydroxyl group, or a combination thereof.