Determination of some red dyes in food samples using a hydrophobic deep eutectic solvent-based vortex assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography.

A simple, sensitive, efficient and rapid method was developed based on vortex assisted deep eutectic solvent dispersive liquid-liquid microextraction (VA-DES-DLLME) of five commonly used synthetic red dyes (amaranth, ponceau 4R, allura red, azorubine, and erythrosine) in food samples and simultaneous determination by high performance liquid chromatography. The novel hydrophobic deep eutectic solvent was readily prepared by mixing thymol as hydrogen bonding donor and benzyltriethylammonium chloride as hydrogen bonding acceptor at 70 °C for 15 min. Affecting parameters on VA-DES-DLLME were evaluated and optimized. Under optimum conditions, the limits of detection were obtained in the range of 0.01-0.08 μg L and linearity of the dyes were also obtained in the range of 0.5-500 μg L (r ≥ 0.99). The enrichment factors and absolute extraction recoveries were in the range of 95-100 and 90-97, respectively. The relative standard deviations (intra-day and inter-days at 10 and 100 μg L concentration levels) were <6%. Finally, applicability of the proposed method was examined by analyzing the food colors in beverage, jelly and chocolate dragee samples and satisfactory results (the relative recoveries ranged from 94.2 to 100.8%) were obtained.