Predicted pKa values are provided by ChemAxon/JChem, and are not based on experimental data, but rather from models that calculate all possible ionization constants based on the molecular structure. Three of the molecules from this set of 23 were selected because of their commonality as matched sets (SAMPL8-7, 8-9, and 8-17). These three weak bases are all benzimidazole scaffolds with molecular weights between 324.2 and 340.2 dalton. One reason for including these three was to ascertain how closely their JChem predicted pKa values align with the experimentally determined pKa values. The JChem predicted pKa values for these three molecules were close together, and averaged 7.56. The experimentally determined pKa's for these three molecules, as reported in Table , average 6.43. The experimentally determined pKa's were 85% less than the predicted values, and provide support to the decision for measuring the ionization constants rather than relying exclusively on the JChem predicted values. The original intent was to select individual pH buffers as the aqueous media depending on the experimentally determined pKa. However, after evaluation of the complete data set, it was concluded that the distribution coefficient experiments could be conducted with standardized pH buffers in groupings. This resulted in running entire sets of distribution coefficient experiments with either pH 3 or pH 8 buffers. This significantly simplified the experimental process, and conveniently eliminated any additional complexity in the automated design.