In situ formation of hydrophobic deep eutectic solvents for ultrasound-assisted microextraction: a greener pathway for monitoring the migration and residue of polychlorinated biphenyls in food contact paper.

An environmentally friendly ultrasound-assisted liquid-liquid microextraction method based on the in situ formation of a hydrophobic deep eutectic solvent (DES) was developed for monitoring seven polychlorinated biphenyl (PCB) congeners as residues in and migrants from food contact paper. The extraction phase was generated in situ from tetrapropylammonium chloride and 1-octanol (molar ratio 1:3), followed by analyte quantification using high-performance liquid chromatography with diode-array detection (HPLC-DAD). Optimization of the parameters affecting extraction efficiency was performed. Under optimal conditions, the method exhibited good linearity and sensitivity. For residual PCB analysis, the limit of quantification (LOQ) was 0.093-0.11 mg/kg; relative recoveries ranged between 89 and 108%; and relative standard deviations were 4-8%. For migration studies, the LOQ was in the range of 0.47-0.53 μg/L, relative recoveries ranged between 90 and 110%, and relative standard deviations were under 9%. The developed method's intra-day and inter-day relative standard deviations were 1.9-2.7% and 2.4-3.6%, respectively. The developed approach offers high extraction efficiency, operational simplicity, and environmental compatibility, demonstrating considerable promise for routine monitoring of PCBs in food contact paper materials.