Effective extraction method for dioxin analysis from lipid-rich biological matrices using a combination of pressurized liquid extraction and dimethyl sulfoxide/acetonitrile/hexane partitioning

For the analysis of dioxins (i.e. PCDDs/Fs, polychlorinated dibenzo-p-dioxins/dibenzofurans, and Co-PCBs, coplanar polychlorinated biphenyls) in lipid-rich biological matrices, we examined the potential of a novel extraction method, consisting of a combination of pressurized liquid extraction (PLE) using 1:9 (v/v) dimethyl sulfoxide (DMSO)/acetonitrile (1:9, v/v) as solvent and DMSO/acetonitrile/hexane partitioning. This method could potentially reduce the large amount of lipids typically generated in the extraction of dioxins. Our cleanup procedure, using tandem multilayer silica gel-activated carbon (MLS-AC) column chromatography, a simplification of the conventional method, was capable of separating mono-ortho-PCBs from non-ortho-PCBs/PCDDs/Fs in half the time required for the conventional method. The optimal conditions for PLE common to all solvents used in this investigation were 2000 psi and >=180 °C. The amount of lipid extracted was approximately 1/100 of that extracted using acetone/hexane (1:1, v/v), making sulfuric acid treatment unnecessary. In both meat and fecal matrices, dioxin congener levels extracted by this method were almost identical to those obtained by conventional solvent extraction methods, such as those employing acetone/hexane or toluene. Moreover, the R.S.D.s of dioxins extracted by this method were <15%, as well as those obtained by conventional techniques. Our new method was advantageous in shortening removing lipid procedure to 2–3 h.