Ultrasound-assisted surfactant-enhanced emulsification microextraction based on the solidification of a floating organic droplet used for the simultaneous determination of six fungicide residues in juices and red wine

A novel ultrasound-assisted surfactant-enhanced emulsification microextraction technique based on the solidification of a floating organic droplet followed by high performance liquid chromatography with diode array detection was developed for simultaneous determination of six fungicide residues in juices and red wine samples. The low-toxicity solvent, 1-dodecanol, was used as an extraction solvent. For its low density and proper melting point near room temperature, the extractant droplet was collected easily by solidifying it at a low temperature. The surfactant, Tween 80, was used as an emulsifier to enhance the dispersion of the water-immiscible extraction solvent into an aqueous phase, which hastened the mass-transfer of the analytes. Organic dispersive solvent typically required in common dispersive liquid–liquid microextraction methods was not used in the proposed method. Some parameters (e.g., the type and volume of extraction solvent, the type and concentration of surfactant, ultrasound extraction time, salt addition, and volume of samples) that affect the extraction efficiency were optimized. The proposed method showed a good linearity within the range of 5 μg L−1–1000 μg L−1, with the correlation coefficients (γ) higher than 0.9969. The limits of detection for the method ranged from 0.4 μg L−1 to 1.4 μg L−1. Further, this simple, practical, sensitive, and environmentally friendly method was successfully applied to determine the target fungicides in juice and red wine samples. The recoveries of the target fungicides in red wine and fruit juice samples were 79.5%–113.4%, with relative standard deviations that ranged from 0.4% to 12.3%.