Two of the nine wrongly classified 'outside' cases were organic complexes that, in the mobile phase, would be analyzed as multiple smaller molecules (e.g., Gadopentetic acid dimeglumine salt). Also, another case was a surfactant containing a positive and negative charge (i.e., 4-Dodecyl-2-[(2-nitrophenyl)azo]phenol). This case was a chemical that falls 'outside' of the RPLC space due to its predicted XLogP value of 10.452. However, the charges on this molecule would make it difficult to calculate this value accurately. Lexidronam was one of the 'maybe' cases that was classified as 'outside', due to a large leverage value of 26.0 and the fact that it elutes at t 0 (i.e., amide scale r i of 206 versus urea r i = 200), indicating the need for special gradients to be able to retain such a chemical. As for the 'inside' cases that were wrongly classified as 'outside', generally larger, branched (e.g., SCHEMBL312614), or hydrolyzing (e.g., Bis [2-(perfluorohexyl)ethyl] Phosphate, respectively) chemicals showed higher likelihood of such misclassifications. Again these are structures that may require very specific adjustment of experimental condition (e.g., pH of mobile phase) to fit them within the RPLC analyzable chemical subspace.