Determination of chlorobiphenyls in cleaned-up seal blubber and marine sediment extracts: interlaboratory study

An interlaboratory study on the determination of individual chlorobiphenyl congeners (CBs) in cleaned-up seal blubber and marine sediment extracts was organized by the International Council for Exploration of the Sea, the Intergovernmental Oceanographic Commission, and the Oslo and Paris Commissions, as the second part of a step-wise-designed interlaboratory study on the determination of CBs in marine media. Fifty-eight laboratories from 16 countries participated in this exercise, which involved the determination of 10 CBs in a standard solution, a cleaned-up seal blubber extract, and a cleaned-up marine sediment extract. Suggestions were given for instrument optimization. Standard errors of 1.16-1.17 for the standard solution, 1.20-1.33 for the seal blubber extract, and 1.31-1.56 for the sediment extract were obtained for CBs 52, 101, 118, 138, 153, and 180 by all laboratories with the exception of the laboratories giving consistently outlying results. The results for CBs 28, 31, 105, and 156 showed larger standard deviations. The 2 major difficulties for participants in this exercise were correct preparation of a calibration solution and chromatographic separation. The results of the sediment analysis showed a complete lack of agreement. It is recommended that, prior to the organization of the third part of this study, participants should install gas chromatographic columns with minimum lengths of 50 m and maximum internal diameters of 0.25 mm and should prepare calibration solutions from solids of known purity.