Response Surface Methodology (RSM)-Based Optimization of Cadmium, Lead, and Copper Ion Extraction from Food Using Deep Eutectic Solvents with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Detection

This study developed a deep eutectic solvent (DES)-based sample preparation procedure using choline chloride (ChCl) and ethylene glycol (EG) for the extraction of Cd, Pb, and Cu from food matrices prior to determination by graphite furnace atomic absorption spectrometry (GF-AAS). Response surface methodology (RSM) based on a face-centered central composite design (FCCCD) was used to optimize the extraction conditions for Sillago sihama muscle, selected as the representative matrix. The optimal conditions were a ChCl:EG molar ratio of 1:1.5, a DES volume of 2.3 mL, a sonication time of 5 min, and thermal treatment at 85°C for 31 min. The method detection limits (MDLs) and method quantification limits (MQLs) for Cd, Pb, and Cu in Sillago sihama muscle were 0.013–0.038 mg kg−1 and 0.042–0.127 mg kg−1, respectively. The optimized procedure was successfully applied to Sillago sihama muscle, chicken liver, dried tea, and coffee powder, giving satisfactory recoveries of 82.5-98.6%. These results demonstrate that DES-based extraction is a reliable, cost-effective, and environmentally compatible alternative for routine monitoring of heavy metals in diverse food products.