Dioxins and furans determination in postmortem blood by gas chromatography--high-resolution mass spectrometry

Dioxins and related compounds (furans) are persistent environmental contaminants that cause adverse biological effects. Their influence on humans is still unclear, except for accidental high-dose exposure. However, chronic exposure to these compounds seems to be involved in cancer, endocrine disruption, and neurobehavioral effects. For several years, a large concern about the potential health risks of dioxins is emerging in Europe and United States. Dioxin levels in biological specimens are extremely low and require very sensitive and specific methods of analysis. In this study, gas chromatography coupled to high-resolution mass spectrometry was used to evaluate dioxin body burden of two women deceased from generalized cancer. Fat fraction of blood specimens was obtained after precipitation with ethanol and extraction of both liquid and solid phases spiked with labeled 13C12-dioxin analogues. Organic phases were grouped, washed, and evaporated to weigh the lipid content. Lipids were dissolved in hexane, hydrolyzed with concentrated sulfuric acid, and discarded during water washes. Dioxins purification was achieved using three successive columns: silica, alumina/sodium sulfate, and carbon/Celite. Finally, the toluene eluent was evaporated and the extract injected in the analytical system. After chromatographic separation, detection was achieved in single ion monitoring mode using a high-resolution mass spectrometer operating in electron impact ionization mode (40 eV, minimal resolution of 10,000). Dioxin levels were expressed in pg TEQ/g of fat as defined by the World Health Organization. Quantification limits for each dioxin congener ranged from 2.5 to 12.0 pg/g fat with a relative extraction recovery always higher than 60%. Dioxin concentrations in the blood of the two deceased women were 35.0 and 42.7 pg TEQ/g fat, respectively. These concentrations are largely lower than those observed after accidental releases, but in the range of those observed in the general European population. Therefore, it was not possible to correlate dioxin body burden of the two women as a potential contributor of their cancer pathology. Nevertheless, knowledge of dioxin body burden in the French population would be of interest for an accurate interpretation of these results.