Evaluation of dialysis as a technique for the removal of lipids prior to the GC determination of ortho- and non-ortho-chlorobiphenyls, using 14C-labelled congeners.
Dialysis was evaluated as a non-destructive clean-up technique to isolate chlorobiphenyls (CBs) from fish-oil prior to further analysis. 14C-CBs were used to study the transfer processes of the CBs across polyethylene membranes. Single step processes using equilibrium dialysis were compared to a dynamic method of refluxing solvent. The dynamic method reduced the duration of the separation to 8 h. The transfer of CBs and the lipids was dependent on temperature and nature of the analyte with smaller molecules being dialysed substantially faster than larger molecules. An optimised dynamic method was used to compare the dialytic clean-up with a traditional method using sulfuric acid-impregnated silica for the determination of CBs in a laboratory reference material. Labelled recovery standards for each individual congener are recommended in combination with dialysis as a method for clean-up.
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FRS Marine Laboratory, Victoria Road, P.O. Box 101, Aberdeen, Scotland, UK AB11 9DB. philipp.hess@marine.ie
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