The n-octanol-water partition coefficient,Kow is a partition coefficient for the two-phase system consisting of n-octanol and water.[1]Kow is also frequently referred to by the symbol P, especially in the English literature. It is also called n-octanol-water partition ratio.[2][3][4]
Kow serves as a measure of the relationship between lipophilicity (fat solubility) and hydrophilicity (water solubility) of a substance. The value is greater than one if a substance is more soluble in fat-like solvents such as n-octanol, and less than one if it is more soluble in water.[citation needed]
If a substance is present as several chemical species in the octanol-water system due to association or dissociation, each species is assigned its own Kow value. A related value, D, does not distinguish between different species, only indicating the concentration ratio of the substance between the two phases.[citation needed]
^Hendriks AJ, van der Linde A, Cornelissen G, Sijm DT (July 2001). "The power of size. 1. Rate constants and equilibrium ratios for accumulation of organic substances related to octanol-water partition ratio and species weight". Environmental Toxicology and Chemistry. 20 (7): 1399–420. doi:10.1002/etc.5620200703. PMID11434281. S2CID25971836.