Study of the Stability of Polycyclic Aromatic Nitrogen Heterocycles in Spilled Crude Oils From Weathering Experiment.

The degradation of toxic polycyclic aromatic nitrogen heterocycles (PANHs) and their alkylated counterparts (APANHs) after an oil spill has not been extensively investigated. A lack of available standards and the available standards' high cost have inhibited progress in understanding their stability in the environment. In the current study, the knowledge gap was reduced by implementing a gas chromatography quadrupole time-of-flight (GC-QToF) method for a cost-effective and time-efficient determination of multiple polycyclic aromatic compounds, including related PANHs and APANHs. Some of the issues related to the availability and high cost of PANH standards were tackled using an adaptation of a high-resolution method that employs polycyclic aromatic hydrocarbons (PAHs) as substitute analog standards. To determine the stability of PANHs and APANHs during weathering, crude oils were subjected to a microcosm experiment, simulating conditions in an aquatic environment found off the West Coast of Canada. Over the course of this study, PAHs, APAHs, PANHs, and APANHs, were observed to follow similar weathering trends. The number of aromatic rings and nitrogen substitution were found to significantly impact the stability of the targeted compounds. This investigation resulted in the identification of twenty, previously un-explored PANH/APANH compounds as potential markers to enhance accuracy and confidence in oil spill forensics, in particular C0–C4 benzo(a)carbazoles, C3–C4 quinoline/isoquinolines, and C0–C4 benzo(c)acridine. [ABSTRACT FROM AUTHOR]