Retention of organic compounds in a humic acid from lignite

Abstract

A lignite humic acid was found to retain a variety of hydrophobic compounds which could be removed by repeated extraction with hexane and chloroform and analyzed by capillary GC and GC-MS. While in the hexane extracts only series of n- and branched alkanes were found, the subsequent extraction with chloroform releases different types of compounds such as saturated, unsaturated, cyclic and branched fatty acids, long chain dicarboxylic acids, long chain w-hydroxyacids and n-alkanols, as well as dehydrophytol and the isoprenoid C18 ketone as individual components. Results on the possible sources and retention mechanisms of these compounds are discussed.