Trace analysis of polychlorinated dibenzo- p-dioxins, dibenzofurans and WHO polychlorinated biphenyls in food using comprehensive two-dimensional gas chromatography with electron-capture detection

Trace analysis of 2,3,7,8-polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs) and the 12 WHO-PCBs (four non- ortho and eight mono- ortho congeners that have been assigned toxic equivalence factors, TEFs, by the World Health Organisation) was conducted by comprehensive two-dimensional gas chromatography with a micro electron-capture detector (GC × GC-μECD). Four food matrices (fish oil from herring, spiked cows’ milk, vegetable oil and an eel extract) were analysed by two GC × GC laboratories, and four GC–HRMS laboratories generated reference values. The two GC × GC laboratories used different column combinations for separating the target analytes. For the first dimension, non-polar DB-XLB and VF-1 columns were used, and for the second dimension, an LC-50 liquid crystalline column with unique selectivity for planar compounds. The congener-specific and total toxic equivalence (TEQ) data obtained using DB-XLB × LC-50 were in good agreement with results obtained by the GC–HRMS laboratories. The WHO-PCB data obtained with the VF-1 × LC-50 combination was also good, but the PCDD/F concentrations were sometimes overestimated due to matrix interferences. GC × GC-μECD using DB-XLB × LC-50 seems to fulfil the European Community requirements of a screening method for PCDD/F and WHO-PCB TEQ in food.