Determination of dioxin-like polychlorinated biphenyls in feed and foods of animal origin by gas chromatography and high resolution mass spectrometry.

The authors describe a method to determine 12 dioxin-like polychlorinated biphenyls (dl-PCBs) in feed and foods of animal origin using high resolution gas chromatography and mass spectrometry (HRGC-HRMS). The use of semi-automated apparatus such as an accelerated solvent extraction device and the Power-Prep purification system significantly reduced the sample treatment time necessary before instrumental analysis in comparison with the Soxhlet extraction method or manual purification on columns traditionally used. This method demonstrated good specificity (mild interference limited to PCB 81 and 123 in highly contaminated matrices, such as fish and fish feed), with limits of detection of 0.2-1.3 pg/g of fat. The coefficients of variation for repeatability tests were in the range of 2.6-18.3%, with recoveries of over 80%. The method was successfully applied to the analysis of 177 samples of various foodstuffs specified in the 2005 Italian National Residues Plan: this is the first data on dioxin-like PCB contamination levels in Italy to emerge under this monitoring plan.