Determination of polychlorinated biphenyls in human blood plasma by on-line and off-line liquid chromatography–gas chromatography

A method for the determination of non-, mono- and di-ortho substituted polychlorinated biphenyls in human blood plasma is presented. The non-ortho CBs are isolated from the bulk of PCBs by HPLC on a dinitroanilino-propyl silica column and collected as a heart-cut fraction that is transferred on-line to GC-MS utilizing concurrent solvent evaporation technique. The on-line coupling serves to lower the limit of determination and to partly automate the sample clean-up. The di- and mono-ortho CBs are analyzed by off-line GC-ECD using two different columns. Sample pre-treatment is performed by extraction with organic solvents and fractionation on silica gel. A high reproducibility and an absolute over-all recovery of approximately 70 % is demonstrated. The method is applied to samples of blood from 5 individuals. All the samples demonstrated a similar relative concentration profile. It was also shown that three CB congeners (CB 126, CB 156 and CB 170) contributed to the major part of the toxic equivalent quantity of the PCB content in the blood.