Results from an international intercalibration study on PCDDs and PCDFs in a fly ash extract

Three fly ash extracts, of which two fortified with different PCDFs and PCDFs congeners, were analysed by eight different laboratories. The results show relatively good precision, RSD for levels reported as TEQs are below 25%. Problems with the analysis of 1,2,3,7,8,9-HxCDF was observed. Multivariate data analysis was performed to explore the data and principal component analyses of the data set revealed clustering of different laboratories.