Miniaturised analytical procedure of determining polycyclic aromatic hydrocarbons and polychlorinated biphenyls in bottom sediments.

This work concerns the determination of very low polychlorinated biphenyl (PCB) concentrations in bottom sediment samples in the presence of large amounts of polycyclic aromatic hydrocarbons (PAHs). A procedure for preparing 1 g bottom sediment samples for GC-MS analysis for the content of PAHs and PCBs is proposed. It consumes a few times smaller amounts of solvents than conventionally used procedures. Naphthalene-d8, benzo[a]anthracene-d12 and PCB 209 were used as internal standards for quantitation purposes; average recoveries of these standards were 65, 55 and 60%, respectively. A home-made glass column filled with ca. 500 mg of activated silica gel was used to isolate the PCB fraction. This has no significant effect on the recovery level of PCB (92-119%). Studies of the effect of homogenisation of a bottom sediment sample on the results of PAH and PCB were conducted. Grinding of bottom sediment samples to a particle size of 0.2 mm had no statistically significant effect on the analytical results and can therefore be omitted, which makes the preparation of the samples definitely less labour- and time-consuming. The interlaboratory study proved that the developed procedure for the simultaneous determination of PAHs and PCBs at largely different concentrations in sediment gives accurate and precise results.