Iwona Barska¹, WIESŁAWa Guz-Ruczyńska¹, Ireneusz Skrzyński¹, Joanna Szlinder-Richert¹, Zygmunt Usydus¹, Piotr Bykowski¹, Helge Hove², Karstein Heggstad² and Annette Bjordal^2
1 Sea Fisheries Institute, Kołłątaja 1, 81-322 Gdynia, Poland
² National Institute of Nutrition and Seafood Research (NIFES), Sentrum 5804 Bergen, Norway

Key words: non-ortho polychlorinated biphenyls, persistent organic pollutants, dioxin-like compounds, Baltic fish, method validation.

Abstract.
The results of determinations of non-ortho PCB contents in Baltic fish and a few fish products are presented. Samples of fillets from herring, sprat, and salmon and from cod liver were examined. A method for determining non-ortho PCB was developed at the SFI Testing Laboratory. It involves purifying samples by dialysis through a semi-permeable polyethylene membrane (SPM) and high-performance liquid chromatography (HPLC). The final determinations were performed with gas capillary chromatography /electron capture detector (GC/ECD).
The contents of four congeners - 77, 81, 126, and 169, which were classified in 1998 by the World Health Organization as dioxin-like compounds, were determined. Based on the results obtained from each sample, the TEQ of non-ortho PCBs was calculated. The highest TEQ (even above 70 pg TEQ-WHO/g sample wet weight) were confirmed in samples of cod liver. In contrast, in other fish samples these values were significantly lower. The TEQ in salmon ranged from 3.5 to 8.4, while those in most of the sprat samples were about 3.0 pg TEQ-WHO/g sample wet weight. The lowest levels of TEQ, ranging from 0.41 to 4.73 pgTEQ-WHO/g sample wet weight, were detected in the herring samples.