Interaction between natural organic matter (NOM) and polycyclic aromatic compounds (PAC) - comparison of fluorescence quenching and solid phase micro extraction (SPME)

The interaction of phenanthrene and 9-aminophenanthrene with natural organic matter (NOM) of different origin was investigated using the fluorescence quenching approach and the solid phase micro extraction method. The results of both methods are compared in terms of the influence of the concentration of the polycyclic aromatic compounds (PAC) as well as the concentration of the NOM on the observed binding constant. Due to the combination of steady-state and time-resolved fluorescence techniques it could be concluded that the observed fluorescence quenching was caused by a static interaction like a complex formation. While for phenanthrene both analytical methods showed no long term effects and the reaction equilibrium between NOM and phenanthrene was established within the first hour, for 9-aminophenanthrene a slow reaction kinetics (within days) was found indicating specific interactions between NOM and the amino group.