HPLC-based method for estimating the temperature dependence of n-octanol-water partition coefficients

Retention time measurements on reversed phase HPLC-columns over a 50 K temperature range are used to estimate the enthalpy of octanol-water phase transfer Delta(OW)H for 38 organic compounds of environmental relevance, including selected chlorinated benzenes (CBzs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated naphthalenes (PCNs) and biphenyls (PCBs). Literature K-OW values as a function of temperature for CBzs served as a reference. Delta(OW)H for these compounds range from 13 to 32 kJ/mol, confirming a relatively minor temperature dependence of their partitioning between water and octanol. For the chlorinated aromatics a strong linear relationship between Delta(OW)H and molar volume was observed. The temperature-dependent retention volumes are also used to estimate K-OW of selected PCNs and PAHs at 25 degrees C.