Multilayered Forensic Protocol Based on In-Depth Mass Spectrometry Techniques for the Investigation of Suspicious Drums of Oils with the 2019–2022 Brazilian Oil Spill Disaster

In 2019, the northeast coast of Brazil experienced the country's largest environmental disaster involving a mysterious oil spill. At the same time, two drums containing an oily substance were found ashore on the coasts of Sergipe and Rio Grande do Norte. Since oil spills are often unavoidable, it was necessary to assess the possibility of simultaneous spills. In this context, a new multilayered protocol is proposed in this work to determine the similarity or dissimilarity between the oily substance in the drums and the suspected samples. Due to geographic proximity, samples from the Sergipe–Alagoas basin were also included as suspects, alongside samples collected from the oil spill. Data obtained from reconstructed-ion chromatograms using m/z 85 and m/z 192, as well as hopane and sterane biomarkers analyzed by gas chromatography-based techniques, trace elements determined by energy-dispersive X-ray analysis (EDX), and ultrahigh-resolution mass spectrometry (UHR MS) data, confirmed that the spilled oils originated from the same event. Furthermore, UHR MS, as an additional analytical layer, helped definitively establish the similarity or dissimilarity relationships between the sample sets when analyzed through principal component analysis (PCA) and hierarchical clustering analysis (HCA). These results suggest that the oil from the drums does not share similarities with oils produced in the Sergipe–Alagoas basin. However, it does show similarities to mysterious oils found on Brazilian northeast beaches in 2019.