INTEGRATING GEL-PERMEATION CHROMATOGRAPHY CLEANUP IN THE ANALYSIS OF METABOLITES OF POLYCHLORINATED-BIPHENYLS, DIBENZO-P-DIOXINS AND DIBENZOFURANS EXTRACTED FROM A MICROSOMAL ASSAY - A COMPARISON OF DIFFERENT MOBILE PHASES

The metabolism of polychlorinated biphenyls, dibenzo-p-dioxins and dib enzofurans (PCBs, PCDDs, PCDFs) can be studied well with a cytochrome P450 containing microsomal assay. In the present study, the residues o f microsomal assays were extracted with organic solvents to determine the metabolites of the studied compounds with GC-ECD and GC-MS. Extrac ts of microsomal assays contained a matrix which interferes with these type of measurements. The matrix was hard to remove completely with s olid phase adsorption chromatography. To overcome the problem of the i nterfering compounds, dean-up properties of a gel permeation chromatog raphy system were studied for this specific matrix. The clean-up was f irstly studied with model compounds and two different mobile phases. T hereupon the most appropriate mobile phase was applied to the extracts of a microsomal assay. Acetone and cyclohexane-dichloromethane (CH-DC M, 1:1, v/v) were compared as mobile phases. The elution profiles of s everal lipids and some organohalogen compounds (OHCs) were determined. The mixture CH-DCM yielded the best separation between lipids and the OHCs. The results were discussed with a theoretical evaluation on the basis of interactions between solute, solvent and stationary phase. R ecoveries were assessed for the GPC procedure and appeared to be good (98-100% for the column itself and 80-100% for the sample transfer fro m vial to column). The GPC was integrated in the clean-up of the extra ct of a microsomal PCDF metabolism assay yielding satisfactory results .