DETERMINATION OF CHLOROBIPHENYLS IN SEAL BLUBBER, MARINE SEDIMENT, AND FISH - INTERLABORATORY STUDY

Between 1988 and 1994, the International Council for the Exploration o f the Sea, the Intergovernmental Oceanographic Commission, and the Osl o and Paris Commissions organized a stepwise interlaboratory study for determination of chlorobiphenyls (CBs) in marine media. The final par ts of this study, in which 53 laboratories from 14 countries participa ted, focused on long-term precision, cleanup, and extraction. Calibrat ion was controlled continuously by analysis of 10 CBs in an unknown so lution. Participants were requested to analyze 3 CBs in a certified re ference material fish oil (6 times); 10 CBs in cleaned and uncleaned m arine sediment and seal blubber extracts; and 10 CBs in seal blubber o il, dried marine sediment, and wet, lean fish muscle tissue. The long- term precision study showed that, compared with earlier exercises in w hich only duplicate analyses were required, repeatability increased ab out 1.5-fold compared with reproducibility. The mean standard error fo r reproducibility of determination of 10 CBs in standard solutions imp roved from 1.22 to 1.15. The standard error improved from 1.36 to 1.28 (without CBs 28 and 31) for seal blubber oil and from 1.36 to 1.22 fo r dried marine sediment. In seal blubber oil and dried marine sediment , the major CBs 118, 138, 153, and 180 can now be determined by the gr oup of participating laboratories with a reproducibility of 1.5 (about 50%). No significant differences were found between results for clean ed-up and uncleaned extracts. No acceptable results could be obtained for determination of CBs in lean fish muscle tissue. Biplots of princi pal component analyses are extremely helpful in evaluating the data ge nerated by this type of study.