The majority of the data identified during the outlier detection procedure contained acidic or basic sub-fragments. This influences the formation of ionic species, which depends on the pK a value of the solute and the pH of the solution. If a compound exhibits an acidic character in its neutral form, it will deprotonate at pH values greater than its pK a , resulting in increased solubility. Similarly, molecules with basic characteristics exhibit higher solubility as the pH decreases below pK a , leading to protonation. This highlights a significant limitation of many current databases, which often lack pK a (or pK b ) and pH information for each species.