The most recent SAMPL6 challenge involved the 11 molecules in fig. that resemble fragments of small molecule protein kinase inhibitors. The challenge organizers encourage participants to consider the effect of water-saturation on the predicted partition coefficients. The experimental log 10 P o * /w 1 values were all positive, indicating a preference for the octanol-rich phase, with values ranging from 1.94-4.09. In general, it was found that the use of water-saturated 1-octanol instead of pure 1octanol only slightly lowered the root mean squared error (RMSE) by 0.05 to 0.10 log units as compared to experiment. Methodological differences and the choice of force field were found to have a greater impact on the prediction accuracy than the composition of the 1-octanol phase .