Enhancement of oil forensic methodology through the addition of polycyclic aromatic nitrogen heterocycle biomarkers for diagnostic ratios

Current oil spill forensic identification of source oils relies upon hydrocarbon biomarkers resistant to weathering. This international technique was developed by the European Committee for Standardization (CEN), under EN 15522–2 Oil Spill Identification guidelines. The number of biomarkers have expanded at pace with technological advances, while distinguishing new biomarkers becomes more challenging due to interference of isobaric compounds, matrix effects, and high cost of weathering experiments. Application of high-resolution mass spectrometry enabled exploration of potential polycyclic aromatic nitrogen heterocycle (PANH) oil biomarkers. The instrumentation showed reduction in isobaric and matrix interferences, allowing for identification of low-level PANH and alkylated PANHs (APANHs). Weathered oil samples, obtained from a marine microcosm weathering experiment, enabled comparison with source oils to identify new, stable forensic biomarkers. This study highlighted eight new APANH diagnostic ratios that expanded the biomarker suite, increasing the confidence for identifying highly weathered oils back to their source oil. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10661-023-10941-3.