The first approach involved plotting the ratio of hydrogens to carbons (H/C) versus the ratio of oxygens to carbons (O/C) in a compound's molecular formula, also known as a Van Krevelen plot . As seen in previous research , polyphenols tend to aggregate in specific regions of the plot. This aggregation was further exemplified when plotting the entries of PhytoHub (Figure ). This region can be split into three parts: phenolic acids, flavonoids, or non-flavonoids. The unknown features which had a molecular formula with a Zodiac score of at least 0.8 were then plotted (Figure ). Features were labeled as phenolic acids if they had a H/C between 0.7 and 1.4 and an O/C between 0.13 and 0.9. They were labeled as non-flavonoids if H/C was between 0.5 and 1.4 and O/C between 0.06 and 0.7. Finally, they were labelled as flavonoids if H/C was between 0.6 and 1.3, and O/C between 0.25 and 0.8. This resulted in 224 features listed in Table and depicted in Figure . The issue with this approach is that due to the similarity of the formulas for each of these three groups, the three sections overlap, e.g. 199 of the features may be a flavonoid or a non-flavonoid due to this overlap. Moreover, as the entire region of flavonoids overlaps with another class, no feature could be indicated as purely flavonoid. Other issues with this approach are that other molecules than polyphenols can fall in the same region of the plot, and it is highly dependent on the accuracy of the molecular formula annotation of the features. Therefore, Van Krevelen plots can be used to easily exclude non-relevant features.