The goal of this work was the isolation of PCBs from different environmental matrices by means of solid-phase (SPE) extraction and gas chromatography/mass spectrometry (GC/MS). The analyses include the determination of PCBs in fourteen samples of transformer oils and different kinds of fodders (for poultry, pigs, and cattle). The recovery rates for different congeners were on the level of 75-85%. The detection limits of five congeners of PCBs were in the range 85 to 130 μg/kg. The RSD was on the level of 2.7 – 4.4%. The Ishikawa diagram was used for evaluation of uncertainty.