Analytical Measurement and Levels of Dioxins and PCBs in Biological Samples

Abstract

Due to the high lipophilicity of dioxins are related compounds, more than 90% of the human exposure to dioxins is due to consumption of lipid-rich food such as meat; milk and dairies, as well as fish and derived products. The measurement of these trace level analytes requires a complex and tedious procedure including sample extraction, sample clean-up, and physico-chemical analysis after chromatographic separation. The determination of dioxins and related compounds requires a method that provides extremely high sensitivity and selectivity. High-resolution gas chromatography (HRGC) in combination with high-resolution mass spectrometry (HRMS) is the 'gold' standard method. In selected ion monitoring (SIM) mode, HRGC-HRMS (10,000 resolution) can achieve detection limit at the femtogram (10(-15) g) level for most of the dioxin congeners. This paper explains the specificities and the pitfalls that could be met by analysts during the analytical development of this particular technique. Sample preparation, cleanup, selection of GC columns, specific aspects of double focusing sector instruments in SIM mode, high-resolution in mass, quantification by isotope dilution technique, quality assurance and quality control requirements and future perspectives are discussed and illustrated. A brief discussion of the bio-analytical approach is also provided to complete the analytical picture. Levels and trends for dioxins in food are discussed in the final part of the manuscript in the context of European regulation.