Preparation of new hydrophobic deep eutectic solvents and their application in dispersive liquid-liquid microextraction of Sudan dyes from food samples

In this work, a new generation of hydrophobic deep eutectic solvents (DESs) was prepared using eugenol (as hydrogen bond donor) and benzyltriethylammonium bromide, benzyltributylammonium bromide, benzyltriethylammonium chloride and benzyltributylammonium chloride (as hydrogen bond acceptor) in different molar ratios. These DESs were applied to vortex-assisted dispersive liquid-liquid microextraction of Sudan dyes from food samples, followed by high-performance liquid chromatographic determination. The influencing parameters, including the type of DES, amount of DES, extraction time, solution pH and salt addition, were investigated and optimized. Under the optimized conditions, a linear range of 2-1000 ng mL^-1 with determination coefficients of <0.999 was obtained. Limits of detection and limits of quantification were in the range of 0.5 to 1 ng mL^-1 and 2 to 3 ng mL^-1, respectively. The proposed method was successfully used in the determination of Sudan dyes in chili sauce, chili powder and ketchup, and satisfactory recoveries of between 89.9 and 119.3% were obtained, with relative standard deviations in the range of 0.1-6.8%. The proposed method is simple, green and efficient, and can be applied to determine Sudan dyes in complex matrices.