Sorption of Polycyclic Aromatic Compounds to Humic Acid As Studied by High-Performance Liquid Chromatography
Aldrich humic acid was chemically immobilized to the silanol surface of a column material to be used for high-performance liquid chromatography (HPLC). The retention factors to the humic acid column material of 45 polycyclic aromatics compounds (PAC) were determined by HPLC. The PAC include PAH, N-, S-, O-PAC and substituted PAC (9-substituted anthracenes, bromopyrenes, and quinoline derivatives). The sorption coefficient of quinoline to humic acid was directly determined at different pH. The good correlation achieved between the HPLC retention factors and literature Koc values, including the presented one of quinoline, was applied to determine Koc of 39 other PAC. The determined Koc values were parametrized with regard to size, ring heteroatoms, and steric and substituent effects and were compared with literature values of water solubility and recently determined octanol−water partition coefficients. It is shown that the sorption of PAC to humic acid is not only affected by hydrophobic interactions but a...