Some advantages of calculating octanol-water partition coefficients

Reliable values for the octanol-water partition coefficients of small solutes used in enzyme binding/inhibition studies are desirable if a hydrophobic effect is being examined. Many investigators will grant that measuring each solute by shake-flask is the ideal, but reversed-phase HPLC data is becoming more commonplace since it is easier to obtain. This note examines one study where HPLC hydrophobicity, from an apparently valid procedure, obscured an obvious hydrophobic relationship. Another example is cited where probable errors in shake-flask measurement also lead to an erroneous conclusion. In both instances, values obtained from a simple method of calculation of log P(o/w) values could have provided a warning.