A non‐targeted gas chromatography/electron capture negative ionization mass spectrometry selected ion monitoring screening method for polyhalogenated compounds in environmental samples

RATIONALE: Many organohalogen compounds with adverse environmental properties have been detected in samples from marine ecosystems. Their quantitation is an important task in environmental analytical chemistry. However, the highly selective gas chromatography/mass spectrometry (GC/MS) selected ion monitoring (SIM) methods developed for this purpose only allow the detection of targeted compounds while unscreened compounds remain undiscovered. The detection of all polyhalogenated compounds in a sample requires the application of non-target methods. METHODS: We present a simple quadrupole-based GC/ECNI-MS-SIM method in which the entire high mass range is screened in eight GC runs using three time windows. Recently developed in the GC/EI-MS mode, this approach has now been adapted to the more sensitive GC/ECNI-MS mode. With this method we analyzed a fraction of a dolphin blubber sample from Australia and a sponge sample from the Mediterranean Sea on polychlorinated and polybrominated compounds and compared the results with the corresponding GC/EI-MS measurements. RESULTS: The non-targeted GC/ECNI-MS-SIM chromatograms were clearly structured and hardly showed co-elutions. Altogether, >400 polyhalogenated compounds were detected in both samples. Many of them originated from unknown compounds. Several new or scarcely analyzed compounds could be tentatively identified. Most of the compounds were not detected with the non-target GC/EI-MS-SIM approach (~150 compounds detected). We also developed a two-dimensional plot in which the mass of the monoisotopic peak was plotted over the GC retention time and which was helpful for the identification of isomers. CONCLUSIONS: Since eight GC runs are required per sample, the method is not aimed for routine analysis. It is recommended as an initial screening method for the analysis of new sample matrices or samples from new regions. The non-targeted GC/ECNI-MS-SIM method benefits from the fact that it can be used with standard equipment.