Separation of polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzo-furans in environmental samples using silica gel and florisil fractionation chromatography

A comprehensive procedure was established for the fractionation of solvent-extracted environmental samples into three fractions containing polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs), respectively. The procedure includes multi-layer silica gel chromatography to separate PBDEs from PCBs and PCDD/Fs, and subsequent separation of PCBs from PCDD/Fs using a florisil column. The numbers of congeners involved were 16, 19, and 17, for PBDEs, PCBs, and PCDD/Fs, respectively. The separation of the three chemical groups overcomes the potential mutual interferences, which are difficult to avoid even by the use of high resolution mass spectrometer (HRMS). In addition, this procedure efficiently eliminates most interfering substances from sample matrices for the subsequent instrumental analyses. The method was validated using mixed chemical standards, and applied for the analysis of environmental samples including sediment, sewage sludge and fish tissue. All the recoveries are within the acceptable ranges specified in the USEPA standard methods.