Figure 5. . Performance of the molecular modeling and quantum chemical calculation pipeline.

(A) A plot of calculated collision cross section (CCS) versus m/z for the protonated forms of the molecules shown in (B), illustrating the degree of orthogonality of the two metrics; (B) metabolite structures from the Human Metabolome Database corresponding to the formula C₆H₁₃NO₂; (C) a plot of CCS versus m/z for 200 metabolites, out of the >11 k solved structures obtained from the Human Metabolome Database. Different colors correspond to CCSs for different metabolites with identical molecular formulae. The data for C₆H₁₃NO₂ from (B) are outlined in the dashed box, and two anthropogenic chemicals with the formula C₁₅H₂₄O, 9-bisabolatrien-11-ol and α-3-copaen-8-ol are shown to have very different CCS; and (D) the theoretical CCS values obtained for selected +H, -H and +Na forms of 11 small molecules show good agreement with experimental CCS values derived from an SPE-ion mobility spectrometry (IMS)-MS platform, with average error of appproximately 2%. All CCS values were predicted using He as the buffer gas.