Hydrophobic deep eutectic solvent-functionalized luffa as biosorbent in a thin film microextraction system (Luffa-HDES-TFME): A novel low-cost method for PAHs analysis in lake water and tea infusion samples.

Biosorbents play a key role in microextraction techniques by improving selectivity and extraction efficiency. Luffa sponge (Luffa acutangula/aegyptiaca), a porous, abundant, and biodegradable lignocellulosic material, remains largely underexplored in this context. This study introduces a hydrophobic deep eutectic solvent-functionalized Luffa integrated into a thin-film microextraction (TFME) system, providing enhanced extraction efficiency, improved sensitivity, and a sustainable alternative to previously reported Luffa-based sorbents. The developed biosorbent was successfully applied in TFME, enabling efficient extraction of five polycyclic aromatic hydrocarbons from lake waters and black tea infusions. For biosorbent development, a 1:1 eutectic mixture of menthol and decanoic acid was selected as the hydrophobic phase. Extraction parameters, including sample volume, extraction time, elution volume, and elution time, were optimized to maximize extraction performance. The developed TFME-HPLC/FLD methodology provided enrichment factors of 27-43, absolute recoveries of 78-87% (intra-day), and limits of detection of 0.02-0.06 ng mL-1. Low analyte levels were found in both environmental and food samples. The developed methodology showed high sensitivity and recoveries while aligning with the principles of green analytical chemistry. Overall, the proposed approach offers a sustainable and efficient alternative for sample preparation, establishing Luffa-HDES as an effective platform for developing green microextraction sorbents.