Validation of a gas chromatography–triple quadrupole mass spectrometry method for confirmatory analysis of dioxins and dioxin-like polychlorobiphenyls in feed following new EU Regulation 709/2014

Abstract

The European Regulations laying down methods of sampling and analysis for the EU official control of levels of polychlorodibenzo-p-dioxins (PCDDs), polychloro-dibenzofurans (PCDFs), dioxin-like (DL) and non dioxin-like (NDL) PCBs in food and feed have been recently amended by EU Regulation Nos. 589/2014 and 709/2014. A major update is the recognition of gas chromatography (GC) triple quadrupole mass spectrometry (GC–QQQMS/MS) as a confirmatory tool for checking compliance with maximum levels (ML). These revisions have been initiated since this technology now exhibits similar performances to GC (magnetic sector) high resolution mass spectrometry (GC–HRMS). In this paper, we show a fully validated method for PCDD/Fs and DL-PCBs analysis in feed material of plant origin (vegetable oil) using GC–QQQMS/MS following the dedicated EU Regulation 709/2014. We show that individual analytical criteria (selectivity, linearity, quant/qual MRM transitions, accuracy around ML of 1.50ng WHO2005TEQ/kg, within-lab reproducibility, robustness, and background subtraction) meet the strict requirements set by the EU Regulation. We also propose a clear interpretation of instrumental limit of quantitation (iLOQ) as a ‘performance-LOQ’, defined in a specific way for GC–QQQMS/MS, and method limit of quantitation (mLOQ) as ‘real-LOQ’ that is used to report bound results. Eventually, the evaluation of measurement uncertainty, following a top-down approach and data produced with our method, demonstrates similar results than with GC–HRMS, thus offering a reliable alternative to the standard method for vegetable oil.