Isomerspecific analysis of pentachlorophenol and sodium pentachlorophenate for 2,3,7,8-substituted PCDD and PCDF at sub-ppb levels

Abstract

So far analyses of pentachlorophenol (PCP) and sodium pentachlorophenate (PCP-Na) for tetra- and CDD/CDF have been carried out mainly at detection limits of 1 ppb or higher (1–7). We have now analyzed 4 commercial PCP and PCP-Na samples for tetra- and pentaCDD/CDF at detection limits of 0.1 ppb. 2,3,7,8-TCDD was analyzed at a detection limit of less than 0.05 ppb (8). This was achieved by two different procedures. 2,3,7,8-TCDD was selectively separated from other PCDD and PCDF by chromatography on basic alumina (8,9). The separation of tetra- and pentaCDD/CDF from hexa- to octaCDD/CDF was accomplished by reversed phase chromatography. Analyses were carried out isomer specific for the 2,3,7,8-substituted PCDD/PCDF. In the two samples of PCP-Na analyzed 2,3,7,8-TCDD was detected at levels of 0.5 and 0.23 ppb respectively, and 1,2,3,7,8-pentaCDD was found in all four samples in concentrations of 0.19 to 18 ppb. It therefore appears no longer valid to consider 1,2,3,7,8-pentaCDD as a “marker” for PCDD/PCDF originating from combustion sources. In the view of these findings the risk assessment for pentachlorophenol and its salts should be reconsidered.