DETERMINATION OF PLANAR PCBS BY COMBINING ONLINE SFE-HPLC AND GC-ECD OR GC MS/

A method for determining non-ortho- and mono-ortho-substituted polychl orinated biphenyls (PCBs) in biological samples has been developed. Hi gh selectivity was obtained by on-line coupling of supercritical fluid extraction (SFE) and high-performance liquid chromatography (HPLC). G as chromatography (GC) with electron capture detection or high-resolut ion mass spectrometry was utilized for quantitative determinations. Gr oup separation of different PCB congeners was achieved on a (2-(1-pyre nyl) ethyl)dimethylsilylated silica column. Compared with off-line HPL C, the on-line coupling to SFE resulted only in a minor reduction in c olumn efficiency. The average recoveries of the planar non-ortho-subst ituted PCB congeners 77, 126, and 169 from crab hepatopancreas were 71 -101%, with the highest recovery for PCB-169. For human blood serum an d milk, the recoveries of the three congeners ranged from 35 to 57% (s erum) and from 76 to 87% (milk), with the lowest recovery for PCB-169. The relative standard deviations of the complete analyses were determ ined to be 5-16%. The recoveries of the on-line SFE-HPLC technique wer e compared to those of conventional solvent extraction and off-line HP LC. For crab hepatopancreas, the two methods gave approximately the sa me result, but for blood serum, slightly higher recovery of the native non-ortho-substituted PCBs was obtained using SFE-HPLC. The present m ethod demonstrates the high speed and selectivity which were obtained by on-line SFE-HPLC as a sample preparation technique prior to GC anal yses for the determination of a group of highly toxic PCBs, usually fo und in very low concentrations compared to the bulk of the PCB congene rs.