Automated fractionation procedure for polycyclic aromatic compounds in sediment extracts on three coupled normal-phase high-performance liquid chromatography columns

Polychlorinated biphenyls, naphthalenes, dibenzo-p-dioxins and furans, as well as polyaromatic hydrocarbons (PAHs), hydroxy-, keto- and nitro-PAHs and sulphur, oxygen and nitrogen heterocycles represent major groups of toxicants in contaminated sediments. The identification of toxic substances in effect-directed analysis is often based on a group-specific fractionation of these polycyclic aromatic compounds (PACs). Several fractionation steps using different methods, solvent exchange and concentration steps are generally necessary to achieve this aim increasing the risk of losses and artefact formation. In order to avoid these disadvantages and to enhance the throughput, an automated on-line fractionation method was developed using coupled and automatically connected columns, including cyanopropyl- and nitrophenylpropyl-bonded silica and porous graphitised carbon stationary phases. Exploiting the potential of each column, compounds are separated mainly according to their polarity, number of aromatic carbons and planarity. Excellent group-specific resolution, high reproducibility and good recoveries suggest that this method is suitable for the fractionation of a multitude of major sediment contaminants in one HPLC-run.