Determination of planar PCBs by combining on-line SFE-HPLC and GC-ECD or GC/MS

A method for determining non-ortho- and mono-ortho-substituted polychlorinated biphenyls (PCBs) in biological samples has been developed. High selectivity was obtained by on-line coupling of supercritical fluid extraction (SFE) and high-performance liquid chromatography (HPLC). Gas chromatography (GC) with electron capture detection or high-resolution mass spectrometry was utilized for quantitative determinations. Group separation of different PCB congeners was achieved on a (2-(1-pyrenyl)ethyl)dimethylsilylated silica column. Compared with off-line HPLC, the on-line coupling to SFE resulted only in a minor reduction in column efficiency. The average recoveries of the planar non-ortho-substituted PCB congeners 77, 126, and 169 from crab hepatopancreas were 71-101%, with the highest recovery for PCB-169. For human blood serum and milk, the recoveries of the three congeners ranged from 35 to 57% (serum) and from 76 to 87% (milk), with the lowest recovery for PCB-169. The relative standard deviations of the complete analyses were determined to be 5-16%. The recoveries of the on-line SFE-HPLC technique were compared to those of conventional solvent extraction and off-line HPLC. For crab hepatopancreas, the two methods gave approximately the same result, but for blood serum, slightly higher recovery of the native non-ortho-substituted PCBs was obtained using SFE-HPLC. The present method demonstrates the high speed and selectivity which were obtained by on-line SFE-HPLC as a sample preparation technique prior to GC analyses for the determination of a group of highly toxic PCBs, usually found in very low concentrations compared to the bulk of the PCB congeners.