Reversed-phase dispersive liquid-liquid microextraction based on decomposition of deep eutectic solvent for the determination of lead and cadmium in vegetable oil.

In this work, a reversed-phase dispersive liquid-liquid microextraction procedure based on the decomposition of deep eutectic solvent was suggested for the first time. The procedure was utilized for fast and simple separation of lead and cadmium from vegetable oil samples. The procedure assumed mixing of oil sample and DES based on menthol, formic acid and water. Water as component of DES promoted its decomposition in sample matrix resulting menthol dissolution in the sample phase and dispersion of aqueous formic acid solution. In this procedure menthol acted as a dispersive solvent during DES decomposition for dispersion of aqueous formic acid solution. The metals were determined by the square-wave anodic stripping voltammetry. The limits of detection, were 0.01 µg kg for lead and 0.006 µg kg for cadmium. The RSD was less then 6% for both analytes. The enrichment factor was 36 and 39 for lead and cadmium, respectively.