(RPLC) and 340 (HILIC), Table . Overall, HILIC was the preferred LC approach for the CSF analysis, with better chromatographic separation on average for compounds detected in both modes. In general, Level 1-2a compounds tended to be endogenous while Level 3e were mainly uncategorized with no PubChem pathways information, as noted above (Figure ). Interestingly, some of the uncategorized compounds in HMDB had PubChem information (Figure ). Drugs and food (Figure ) constituted the main exogenous subcategories of the MS-DIAL annotations.