Physical factors negatively affecting evaluation of long-term biodegradation experiments of polychlorinated biphenyls.

Behaviour of PCB added in the form of a technical mixture (Delor 106) and [14C]PCB 77 into different aqueous model cultivation media in long-term experiments was studied. The work was focused on monitoring PCB recovery from liquid media in the absence of micro-organisms. GC-ECD and radioanalysis were utilised for determination of PCB in the examined systems. Strong relations between duration of experiments, composition of media, degree of chlorination of biphenyls, and recovery of PCB were found. The lowest yields of PCB were observed for the extracts from model solutions based on N-limited cultivation media without veratryl alcohol and Tween 80. The addition of these components, mainly of Tween 80, caused a significant increase of PCB recoveries.

Evaluation of methods for the determination of chlorophenols in surface water.

Three methods for the determination of chlorophenols in surface water have been evaluated. Two of them utilize solid phase extraction followed by derivatization either in aqueous phase or in organic solvent. The third method is based on liquid-liquid extraction with simultaneous in-situ derivatization. This method was found to be not applicable for samples of surface water. The surfactants present in the samples prevent the separation of the hexane layer at a ratio of 1 : 20 or higher. Both methods using solid phase extraction gave acceptable results; however, the derivatization in aqueous phase proved its priority.

Reversed-phase liquid chromatography of aromatic nitro compounds on a macroporous polystyrene gel.

The retention behaviour of some nitrobenzene derivatives was studied by reversed-phase chromatography on the macroporous polystyrene gel Separon SE with methanol-water, acetonitrile-water, tetrahydrofuran-water and methanol-water with adjusted pH as the eluents. The effect of the mobile phase and the presence of additional polar and non-polar substituents in the molecule of the solute on the retention were investigated. Using methanol-water (80:20) the contribution of the nitro group to the retention of the molecule is positive for substances containing both polar and non-polar functional groups. The contribution of the nitro group did not change if a mobile phase with adjusted pH was used. With acetonitrile-water and tetrahydrofuran-water the situation was more complicated.