Development of a short and sensitive QuEChERS-SPE-GC-MS method for polycyclic aromatic hydrocarbon (PAH) biomonitoring in Perna perna (Linnaeus, 1758) mussels from an oil-impacted tropical estuary.

The 2019 oil spill in Guanabara Bay, among the most significant in Brazilian history, has reinforced how persistently PAHs move through food webs significant to artisanal fishing communities. However, low-cost tools for tracking these contaminants in key sentinel species, such as bivalves, remain scarce, especially for matrices that resist conventional extraction protocols. In this sense, this study developed a dual-extraction method combining Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) and solid-phase extraction (SPE) clean-up to quantify multiple PAHs in Perna perna mussels sampled from Guanabara Bay, Brazil overcoming matrix interference to deliver faster, cheaper and more actionable contamination data for a subsistence food source. A total of 210 mussels were collected across four artisanal fishing communities in Guanabara Bay, a socially and ecologically critical estuary, 2 to 3 years after the spill. The method achieved strong linearity (r2 > 0.995) and acceptable recovery (51.1-109.0%) for 15 of 18 target PAHs. Only five compounds were quantified above the Limit of Quantification, with special focus on benzo(a)pyrene, with a high-molecular-weight and predominantly pyrogenic signature pointing to a diffuse, combustion-derived background rather than a lingering trace of the spill. This finding highlights the value of the proposed method, of a practical, affordable tool that is extensible to oil-impacted tropical estuaries worldwide for routine PAH biomonitoring.