RESULTS FROM THE 2ND ROUND OF THE INTERNATIONAL INTERCALIBRATION ON PCDDS, PCDFS AND PCBS IN A FLY-ASH EXTRACT

The second round of an international intercalibration exercise on the determination of PCDD/DFs and planar PCBs in a fly ash extract took pl ace in 1995/96. Thirty laboratories from around the world were partici pating, 25 of them were able to produce results before the expiration of the dead line. Six extracts from three batches were sent to the par ticipants who reported the levels of all 2,3,7,8-substituted PCDD/DF c ongeners, PCB #77, #126 and #169 plus the total of PCDD/DFs at each ch lorination level. The results showed good agreement between 21 laborat ories with a RSD below 15% for the total TEQ. The results were further evaluated with multivariate statistics. Plots from principal componen t analyses identified analytical problems for some of the participants , but clustering of the majority of the participants. (C) 1998 Elsevie r Science Ltd. All rights reserved.