Reversed-phase thin-layer chromatography of polynuclear aromatic hydrocarbons and chlorinated biphenyls : Relationship with hydrophobicity as measured by aqueous solubility and octanol-water partition coefficient

Abstract Reversed-phase thin-layer chromatography with methanol-water as eluent was used to study relationships between retention and hydrophobicity of non-polar aromatic compounds. For polynuclear aromatic hydrocarbons, n -alkyl- and chloro-substituted benzenes, good correlation was observed between R m values and log P octanol . Significantly different correlations were obtained for polychlorinated biphenyls (PCBs) containing chlorine atoms in the positions ortho to the phenyl-phenyl bond. This effect could not be explained by the measured lower π octanol values for ortho chlorine in PCBs. Estimation of hydrophobicity from aqueous solubility, S , combined with melting point data is restricted to S values higher than 1 μg/l. A group-contribution approach, including a retention index scale, will be very useful for correlation and prediction of reversed-phase retention, hydrophobicity and environmental and toxicological properties of chemicals.