An example from the zoomed-in cluster (Figure ) showed different nodes annotated as 11-HETE employing NEO-MSMS library (i.e., the black squares of m/z 319.228 in the Figure ) which potentially correspond to different isomers due to the difference on the retention times (max. difference of 0.09 min). These nodes are linked with another two with virtually identical mass spectra (cosine score 0.9929), m/z 347.259 (C22H35O3), which could correspond precisely to a monohydroxyl derivative of a fatty acid with the formula C22H36O2. Similarly, the node with m/z 345.244 (C22H34O3) may correspond to a monohydroxyl derivative of C22H34O2, and m/z 293.2122 (C18H29O3) to the monohydroxyl derivative of C18H28O2. The position of the hydroxyl group relative to the end of the chain plays a crucial role in connecting compounds of the same family. For example, an OH group at position 11 of a C20 can easily be linked to a monohydroxyl compound with an OH group at position 13 of a C22, or an OH group at position 9 of a C18. The study of the MS/MS spectrum clearly demonstrated that the compound with m/z 347.259 corresponds to 13-hydroxy-7Z,10Z,14E,16Zdocosatrienoic acid (13-HDT) a metabolite of adrenic acid (the 16 th isomer position could potentially be E). This is supported by the specific fragments at m/z 195 and m/z 223, as shown in Supplementary Information Figure .