Report on the results of the ICES/IOC/OSPARCOM intercomparison exercise on the analysis of chlorobiphenyl congeners in marine media (Step 1) and The intercomparison study of the determination of CBs in Baltic herring oil.

This report gives an account of the results of the first step of the ICES/IOC/OSPARCOM Intercomparison Exercise on the Analysis of Chlorobiphenyl Congeners in Marine Media. Results were received from 62 laboratories. An encouraging agreement has been achieved, with standard deviations for reproducibility of 1.11-1.12 for all CBs except CB 52 for a group of 47 laboratories. The optimization procedure of the gas chromatograph (GC) was experienced by many participants as a valuable learning process. This optimization of the GC conditions has led to a better level of agreement in comparison with former intercalibration exercises on CB analysis. Difficulties were experienced with the identification of the linear range of the electron capture detector and bringing the unknown solution within this linear range. Results based on peak heights showed a better reproducibility than results based on peak areas. The separation of CBs 28 and 31 was the most difficult one. Only 28 laboratories were able to achieve a separation of these two CBs. It is concluded that the second step of this exercise may be organized now. This step will involve, in principle, an analysis of a cleaned-up blubber and a sediment extract.