The octanol-water partition coefficient
This parameter is of great interest for the development of an extraction method. It represents the partition coefficient, at equilibrium, of the solute in the presence of a mixture (immiscible) of water and octanol.
![](/resources/images/fiches/methodologie/extraction/en/22-image-extraction.png)
The more hydrophobic the compound, the higher its Kow.
This coefficient is related to water solubility but has the advantage of being unitless – it is therefore easier to work with than solubility and allows a simple hydrophobicity scale to be drawn up.
![Scale of hydrophobicity log Kow. Below 2: hydrophilic. Between 2 and 4: hydrophilic to hydrophobic. Above 4 : hydrophobic.](/resources/images/fiches/methodologie/extraction/en/23-image-extraction.png)