GC×GC–ToF MS FOR THE ANALYSIS OF ANTHROPOGENIC AND NATURALLY PRODUCED ORGANOBROMINATED COMPOUNDS

Introduction Comprehensive two-dimensional gas chromatography (GC×GC) has gradually been introduced to solve some separation problems found during the analysis with one-dimensional GC. The use of high speed time-of-flight mass spectrometry (HS-ToF MS) as a detector for GC×GC (GC×GC–ToF MS) adds an additional dimension to the analysis allowing unambiguous determination based on nominal mass. This is especially relevant for environmental applications dealing with the determination of individual isomers belonging to complex families of micropollutants, e.g. polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and other closely related persistent organic pollutants (POPs). Many studies have proved that one-dimensional GC systems, especially when combined with MS detectors, provide enough resolution to allow unambiguous determination of relevant congeners within complex families, such as PCBs, PBDEs and PCDD/Fs. However, in these studies, either an exhaustive clean-up and fractionation of the extracts or several GC runs are typically required, especially when different classes of analytes have to be determined in the same extracts. In addition, most studies are target-orientated and information concerning the possible presence of other relevant known and especially unknown micropollutants is lost. In this context, GC×GC and, especially GC×GC–ToF MS, are powerful analytical tools that simultaneously contribute to simplify sample treatment and allow simultaneous determination of trace compounds from different analytes classes, while preserving complete information regarding non-targeted compounds. The feasibility of the technique to provide structured chromatograms is an additional feature that efficiently contribute to the tentative identification of analytes and families of analytes for which standards are not available and so to the (virtual) identification of unknown compounds . Up to now, the number of studies in which the simultaneous screening of relevant organobromines (OB) have been done are scarce in the literature . These studies have covered a wide range of OB families, including new brominated flame retardants (NBFRs), some methoxylated brominated biphenyl congeners (MeO-PBBs), other methoxylated phenoxyanisoles (mono and di-MeO-PBDEs) and several organohalogenated methyl and dimethyl bipyrroles (MBP and DBPs). These databases provide a useful tool for tentative identification and/or confirmation of non-targeted compounds when standards are not available. The present work focuses on the separation and detection via GC×GC–ToF MS of a number of environmentally relevant OB families, including PBDEs, environmentally relevant MeO-PBDEs, and other naturally-produced organohalogens (HNPs), such as the polybrominated hexahydroxanthene derivates (PBHDs), 2,4,6-tribromoanisole (TBA) and a mixed halogenated monoterpene compound (MHC-1), in 26 bluefin tuna muscle samples (Thunnus thynnus). Special attention was paid to solve analyte co-elutions previously observed in the one-dimensional GC analysis. In addition, tentative identification of other NBFRs as well as elucidation of some non-identified OBs detected in the samples was carried out.