TURK 2025

Due to the carcinogenic and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs), the determination of these compounds in environmental samples is a critical analytical challenge. Given the typically low concentrations of PAHs in water samples, extraction and preconcentration are necessary prior to their analysis. Conventional methods for extraction and preconcentration of PAHs include liquid-liquid extraction (LLE) and solid-phase extraction (SPE), both of which require organic solvents. In contrast, solid-phase microextraction (SPME) is a solvent-free technique that commonly employs an optical fiber coated with a thin layer of polymeric material to extract analytes from various matrices, such as water, soil, and gaseous samples. The extracted analytes are thermally desorbed in the injection port of a gas chromatography system. In this study, a SPME method was developed using an optical fiber coated with a graphene oxide-polyvinyl imidazole (GO-PVI) nanocomposite prepared via the sol-gel method. The porous GO-PVI layer is coated onto the optical fiber using silicone. Compared to conventional polymeric coatings like polydimethylsiloxane (PDMS), the porous particles provide a larger specific surface area, resulting in higher adsorption capacity. The headspace SPME (HS-SPME) method utilizing the GO-PVI coating was applied to separate selected PAHs from aqueous samples. Key parameters affecting SPME efficiency, including analyte desorption time, desorption temperature, extraction time, extraction temperature, and salt effect, were investigated and optimized. Under optimal conditions, linear ranges were established for biphenyl, acenaphthylene, fluorene, and anthracene. The limits of detection for the studied compounds ranged from 0.33 to 0.97 ng/mL. The recovery of PAHs from aqueous samples was determined, with the lowest and highest recovery percentages corresponding to anthracene and fluorene, respectively. The extraction of PAHs using the GO-PVI coating exhibited high reproducibility, with relative standard deviations (RSD%) ranging from 0.053% to 0.105% for different PAHs. Water samples collected from various sources were analyzed, and the presence of certain PAHs was confirmed in some samples using GC/MS. The chemical bonding in the GO-PVI coating significantly addressed issues associated with traditional fibers, such as instability at high temperatures. Unlike traditional fibers, which are unstable above 220°C, the new fiber remains stable up to approximately 320°C. The fiber’s lifespan increased from 50–100 uses for traditional fibers to over 190 uses for the sol-gel-prepared fibers. Another significant aspect of this project is the synthesis of an organic-inorganic copolymer with an organic vinyl imidazole structure, which imparts polarity to the fiber. This polarity enhances extraction efficiency through π-π interactions between the polyvinyl imidazole and the aromatic rings of the studied PAHs. Electron microscopy images revealed that the fiber surface is porous, increasing the contact surface area during extraction and thereby improving efficiency. The thin GO-PVI/sol-gel coating, estimated at approximately 30 µm, is significantly thinner than traditional fibers, enabling faster extraction equilibrium (adsorption and desorption) and minimizing carryover effects from previous samples, which is another advantage of the developed fiber. Additionally, a custom-designed holder (syringe) was developed to protect the fragile glass-based fibers, providing robust protection against impacts and drops.