The 1994 QUASIMEME laboratory-performance studies: Chlorobiphenyls and organochlorine pesticides in fish and sediment

Two laboratory-performance studies have been undertaken to improve the measurement of chlorobiphenyls (CBs) and organochlorine pesticides (OCPs) in marine sediments and biota as part of the QUASIMEME (EU-Standards, Measurements and Testing) projectʹs on-going Laboratory Testing Scheme. Forty and 38 laboratories, respectively, participated in the two exercises. A considerable improvement was obtained in the long-term precision of the participating laboratories. The between-laboratory variance for the determination of CBs and OCPs in the cod liver homogenate and dried sediment samples was, however, too high for the rather demanding requirements of international monitoring programmes. Detection of a 50% change in concentration of CBs is a minimum requirement for such programmes, whereas currently detection of a 100% change in concentration would maybe just be possible for some analyses in sediments and cod liver. Several individual laboratories performed, however, considerably better compared to the group performance. A number of improvements such as optimization of the temperature programme of the GC analysis, a larger sample intake and treatment of co-extracted interferences is recommended.