Information (scoring term 7). Candidates were ranked and given a score per category normalized to 1, then added together to obtain the max_Score, with the highest possible score = 7. A more detailed explanation of the parameters used is available elsewhere. Annotation confidence levels were determined using the scheme described by Schymanski et al. Level 2a compounds were assigned when the MoNA score was greater than or equal to 0.9. Level 1 identifications were achieved using authentic standards and the ENTACT mixtures , available in-house and analyzed using the same chromatographic method used for sample analysis. The ENTACT mixtures were obtained from participation in the EPA's Non-Targeted Analysis Collaborative Trial. Retention times were considered a match if the difference was less than 0.2 minutes. The compound classification for the compounds identified was obtained by consulting PubChem's 'Drug and Medication Information' section, based on a specific drug's therapeutic use or function. Level 3 confidence was given for compounds with max_Score > 6.0 but with MoNA scores less than 0.9 (103 compounds), however, the scope of the paper has been limited to Level 2a and Level 1 chemicals at this stage due to their higher confidence.