Gas chromatographic/mass spectrometric analysis of human serum for non-ortho (coplanar) and ortho substituted polychlorinated biphenyls using isotope-dilution mass spectrometry

We have synthesized in our laboratory all of the totally carbon-13-labeled PCBs normally found in human tissues. The mixture of carbon-13-labeled PCBs consists of more than 50 congeners including the ¹³c₁₂-labeled, coplanar, non-ortho substituted PCBs. We used this spiking material to prepare analytical standards at various concentration levels, and established standard curves using isotope-dilution mass spectrometry for each congener over a range of concentrations normally found in human samples. The PCBs were analyzed on a Finnigan MAT 4500 in either the electron-impact or negative-ion chemical ionization mode on a DB-5 capillary column.