GC×GC-TOFMS QUANTIFICATION OF ALKYLATED AND PRIORITY POLYCYCLIC AROMATIC HYDROCARBONS IN SEDIMENTS AFFECTED BY DIFFERENT ANTHROPOGENIC SOURCES

Alkylated polycyclic aromatic hydrocarbons (APAHs) and priority polycyclic aromatic hydrocarbons (PAHs) are associated with petroleum and combustion-derived inputs and can accumulate in sediments. Their determination is challenging due to low concentrations, numerous isomers, coelution, and limited availability of standards for alkylated homologs. This study aimed to simultaneously quantify 23 APAHs and 16 priority PAHs in sediments under different anthropogenic influences using GC×GC-TOFMS combined with microscale extraction. Chromatographic separation employed Rxi-5Sil MS (60 m × 0.25 mm × 0.25 µm) and Rxi-17Sil MS (2 m × 0.25 mm × 0.25 µm) columns in the first and second dimensions, respectively. The method provided linear responses from 0.1 to 80 µg L⁻¹ (R²=0.97–0.99), LODs of 3.44–14.96 ng g⁻¹, LOQs of 8.48–29.88 ng g⁻¹, and recoveries of 97.9–116%. It was applied to 23 sediment samples from 11 areas affected by petrochemical, industrial, and port activities (Paraguaçu River – PGR, Subae River - SBR, Mataripe - MP, Sao Paulo River - SPR, Santo Amaro - SAM, Madre de Deus - MDU, Baiacu - BCU), human occupation (Camamu Bay-CB, Jaguaripe River-JGR, Jacuruna-JC), and domestic waste and effluents inputs (Salinas Margarida-SAL, Camamu Bay-CB, Paraguaçu River). GC×GC-TOFMS resolved isomers of methylchrysenes, which partially coelute under one-dimensional GC conditions, demonstrating the enhanced resolving power of the two-dimensional approach. APAHs predominated over priority PAHs in several samples, particularly alkylated naphthalenes (1,4-DMNap, 2-MNap, and 2-ISPNap) and phenanthrenes (3,6-DMPhen and 1-MPhen). Concentrations above 4000 ng g⁻¹ were observed for APAHs in samples from the RSB, BCU, SAM, and CB. The predominance of low-molecular APAHs is consistent with petrogenic contribution, particularly in BQ, CB, and selected RPG and RSB showing profiles compatible with relatively light and less-weathered petroleum-derived inputs. In BQ, the occurrence of 2-MNap, 2-ISPNap, and 9-MFlu reflects inputs associated with oil and natural gas production activities in the Itaparica field. In CB, 1-EtNap, 1,4-DMNap, 3,6-DMPhen may be associated with human occupation domestic waste inputs, while in RPG the presence of a broad range of target compounds may reflect multiple inputs from industrial activities, maintenance operations, domestic effluents. In RSB, 6/2,7-DMNap, 2,3,5-TMNap, 1,4,6,7-TMNap, 2-MPhen, and 2-MAnt was consistent with inputs from the petrochemical complex, port activities, and industrial sources. In contrast, RSP exhibited a broader molecular distribution, including higher-molecular-weight compounds such as 1-MChr, B[a]Ant, and B[b]F, suggesting a more complex or mixed contamination profile. Overall, GC×GC-TOFMS enabled simultaneous quantitative profiling of APAHs and priority PAHs while improving isomer resolution, providing detailed molecular information to support source assessment in complex sediment matrices.