Determination of PCDD/DFs in paper clay samples

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) were measured in paper clay samples with TEQ ranging from 14 pg TEQ/g to 4955 pg TEQ/g dry matter. Two different types of PCDD/DFs profiles were found in samples containing pentachlorophenol (PCP). Most samples agreed well with the PCDD/DFs profiles reported in PCP. One sample containing 4955 pg TEQ/g was contaminated by an additional 2,3,4,6-tetrachlorophenol source. Preliminary data indicated that a significant fraction of PCDD/DFs and PCP were retained in aged samples and finished products.