Freezing temperature controlled deep eutectic solvent dispersive liquid–liquid microextraction based on solidification of floating organic droplets for rapid determination of benzoylureas residual in water samples with assistance of metallic salt

An efficient and novel salt-assisted deep eutectic solvent (DES) dispersive liquid–liquid microextraction based on solidification of floating organic droplets combined with high performance liquid chromatography was developed for extraction and determination of four benzoylureas (BUs) in water samples. In this method, a hydrophobic deep eutectic solvent (DES) used as extractant was dissolved in a dispersive-demulsified solvent containing FeCl3. The influence of main factors on the efficiency of this procedure was investigated by one-factor experimental design and central composite design (CCD) successively. Under optimal conditions, the proposed method manifest good recoveries in the range of 82.36–93.82% and high precision (relative standard deviations below 5%). The enrichment factors for the analytes changed from 91 to 97. The limits of detection varied from 0.11 to 0.35 μg L−1 with the linear coefficients greater than 0.999. The method is successfully applied to determine the BUs in different water samples, which proved the potential use of this method in real samples.