Interlaboratory study of PCDDs and PCDFs in fly dust from a municipal incinerator

In order to validate results, subsamples of fly dust were analysed for congener groups of PCDDs and PCDFs (tetra to octa) by two laboratories. Sample extracts were exchanged during different stages of the analytical procedure. Major differences in results (up to a factor 3) were introduced in GC/MS analysis, whereas only minor influences could be ascribed to differences in sample treatment techniques. Finally, analysis of another serie of fly dust samples, using modified methodologies, showed that analytical data were in good agreement.