Natural deep eutectic solvent based on camphor and citral as effective and safe extractant for the determination of polycyclic aromatic hydrocarbons in foods.

In this work, a new environmentally friendly natural deep eutectic solvent based on two natural compounds, camphor and citral, was proposed for the first time. The solvent exhibits favorable physicochemical properties, including stability in the presence of water, low viscosity, and good solubilizing capacity. The proposed solvent was investigated by FT-IR and 1H NMR spectroscopy. The solvent was successfully applied for the extraction and determination of 11 polycyclic aromatic hydrocarbons in food samples (cucumber, salad, and tea infusion) by high-performance liquid chromatography with fluorescence detection. The formation of hydrogen bonds between camphor (ketone) and citral (aldehyde) resulted in the effective extraction solvent capable of interacting with non-polar polycyclic aromatic hydrocarbons via lipophilic and π-π stacking interactions. The proposed microextraction procedure provided high enrichment factors (49-68) and satisfactory extraction recoveries (71-98 %). Under optimized experimental conditions, the limits of detection ranged from 0.1 to 0.3 μg kg-1, while typical maximum residue limits for polycyclic aromatic hydrocarbons in foodstuffs range from 1.0 to 5.0 μg kg-1.