Reversed Phase (RP) Methods. Mobile phases in RepoRT include water (H2O), MeOH, ACN, isopropanol (iPrOH), and acetone (ACE). Since the methods using ACE and IPA only describe 293 and 378 unique retention times, respectively, we exclude them from our dataset. We also exclude all gradients containing more than two distinct mobile phases. We ensure that all mobile phases are described such that the solvent A is the aqueous component, and solvent B is the organic. All gradients with a non-constant flow rate are also excluded from our training dataset. All gradients with t0 greater than 3 minutes were excluded from our dataset because of the high variability associated with the measured RTs. As has been performed in other studies using the METLIN SMRT dataset, we exclude all molecules not retained on the column because of the large error associated with the dataset bimodality. Our final, pruned, RepoRT dataset consisted of 191 unique methods, totaling 142,668 retention times, and 89,643 unique SMILES strings. Summary statistics for the chemical and chromatographic makeup of this dataset are available in Figures .