Performances and limitations of the HRMS method for dioxins, furans and dioxin-like PCBs analysis in animal feedingstuffs, Part I: Results of an inter-laboratory study

The European strategy for dioxin monitoring of the food chain has defined high-resolution gas chromatography coupled to high-resolution mass spectrometry (HRGC/HRMS) method as the confirmatory method that can provide reliable and comparable results at sub-parts per trillion (ppt) level. This paper describes the first inter-laboratory study on dioxins, furans and dioxin-like PCBs by HRGC/HRMS method in animal feedingstuffs. Two different statistical approaches (ISO 5725 and Cofinoʹs statistics) were used for the statistical evaluation. For this particular study, the performances of the HRGC/HRMS method seem to be congenerindependent in repeatability and reproducibility conditions over a concentration range covering more than four orders of magnitude. Results clearly show the effect of precision loss below 0.1 ppt level per congener in repeatability conditions and below 0.2 ppt level per congener in reproducibility conditions. LODs reported by the laboratories give median values of 0.02 ng/kg for most of the toxic congeners. Relative standard deviation between the laboratoriesʹ mean values using upper-bound approach for TEQ calculation is 6.2%, more than twice the maximum level set at 0.75 ng TEQ/kg of product.