Report on the results of the ICES/IOC/OSPARCOM intercomparison programme on the analysis of chlorobiphenyls in marine media-step 2, and the intercomparison programme on the analysis of PAHs in marine media-stage 1

This report gives an account of the second step of the ICES/IOC/OSPARCOM Intercomparison Programme on the Analysis of Chlorobiphenyls (CBs) in Marine Media. Results were received from 58 laboratories in sixteen countries. In this exercise, CB Nos. 28, 31, 52, 101, 105, 118, 138, 153, 156 and 180 were analysed in an unknown CB solution, a cleaned seal blubber extract, and a cleaned sediment extract. An extra test, which included the analysis of an unknown CB solution vs. a supplied known solution, was carried out by laboratories that produced outlying results in the first exercise and laboratories who participated for the first time in this second exercise. Standard deviations for reproducibility of 1.16 - 1.17 for the standard solution, 1.20 - 1.33 for the cleaned seal blubber extract, and 1. 31 - 1.56 for the cleaned sediment extract were found for all laboratories without outliers for CBs 52, 101, 118, 138, 153 and 180. The results for CBs 28, 31, 105 and 156 showed larger standard deviations. The two major difficulties identified for participants in this exercise were the preparation of calibration solutions and the chromatographic separation. It is suggested that in any further exercise results will only be accepted when based on calibration solutions prepared from solids of known purity and analysed with two columns with different stationary phases and minimum lengths of 50 m and maximum internal diameters of 0.25 mm. The third step of this exercise should be undertaken only after the laboratories have been given time to revise their methods and install the necessary gas chromatographic columns. A repeat exercise using an unknown CB solution is suggested, along with analysis of an uncleaned seal blubber extract. The common quality level for the analysis of sediment extracts is considered to be far from what is required. Therefore, it is suggested to wait with further action until improvement is obtained with the standard solution and the uncleaned seal blubber extract. To five laboratories, advice was given not to participate in further steps of this exercise, because their calibration  procedures and chromatographic methods first need a drastic revision. Eleven laboratories that did not produce any results, even three months after the deadline, should be excluded from further participation until the present learning exercise is concluded.