Reversed-phase thin-layer chromatography of polynuclear aromatic hydrocarbons and chlorinated biphenyls

Abstract

Reversed-phase thin-layer chromatography with methanol-water as eluent was used to study relationships between retention and hydrophobicity of nonpolar aromatic compounds. For polynuclear aromatic hydrocarbons, n-alkyl- and chloro-substituted benzenes, good correlation was observed between Rm values and log Poctanol [octanol partition coefficient]. Significantly different correlations were obtained for polychlorinated biphenyls (PCB) containing Cl atoms in the o-positions to the phenyl-phenyl bond. This effect could not be explained by the measured lower .pi.octanol values for o-chlorine in PCB. Estimation of hydrophobicity from aqueous solubility [S] combined with melting point data was restricted to S values > 1 .mu.g/l. A group-contribution approach, including a retention index scale, would be useful for correlation and prediction of reversed-phase retention, hydrophobicity and environmental and toxicological properties of chemicals.