Optimization of high-performance thin-layer chromatography cleanup for compound-specific carbon anf hydrogen stable isotope analysis of polycyclic aromatic hydrocarbons in marine sediments

초록

Background : Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants with carcinogenic potential, commonly accumulating in marine sediments due to their hydrophobic nature. Accurate source identification of PAHs is essential for pollution control but remains challenging in complex matrices because of their low concentrations and the presence of co-eluting substances, such as unresolved complex mixture (UCM). Compound-specific isotope analysis (CSIA) of PAHs offers improved diagnostic resolution; however, it requires highly purified analytes. This study addresses the methodological challenge of effectively isolating individual PAHs from sediments for accurate delta C-13 and delta H-2 measurements without isotopic fractionation. Results : We developed an optimized pretreatment protocol integrating silica gel column cleanup and high-performance thin-layer chromatography (HPTLC) for CSIA of PAHs in marine sediments. Among the five solvent systems tested, a hexane:dichloromethane (70:30, v/v) mixture provided the highest compound purity (up to 96%) and the most precise stable isotope ratios (SD < 0.5 parts per thousand for delta C-13; <5 parts per thousand for delta H-2). Application to sediments from three Korean industrial harbors enabled clear isotopic differentiation of PAH sources, indicating varying contributions from low-temperature pyrolysis, fossil fuel combustion, and petrogenic emissions. The method demonstrated strong reproducibility and successful UCM removal with no isotopic fractionation. Significance : This study establishes a robust HPTLC-based cleanup strategy for reliable CSIA of PAHs in marine sediments. It enhances isotopic resolution, enabling accurate pollution source attribution in environmental forensics. The method is broadly applicable to other organic contaminants and matrices, contributing to regulatory monitoring and pollution control.

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