Determination of Synthetic Colorants in Beverages by Deep Eutectic Solvent-Based Effervescence-Assisted Dispersive Liquid–Liquid Microextraction Coupled with High-Performance Liquid Chromatography

In this paper, a deep eutectic solvent (DES)-based effervescence-assisted dispersive liquid–liquid microextraction method was proposed for the determination of four synthetic colorants in beverages by high-performance liquid chromatography. In this method, DES synthesized from choline chloride and phenol was used as extractant. The dispersion of DES was assisted by in situ CO2 produced from the effervescence reaction between NaH2PO4 and Na2CO3 without using any organic solvent or auxiliary equipment. Furthermore, phase separation occurred naturally in the presence of the salt products of effervescence reaction, without the addition of any other salting out reagents. Some important parameters, such as species, molar ratio and volume of DES, composition and amount of effervescent agents, were optimized to achieve the best extraction efficiency. Under the optimal conditions, extraction recoveries were obtained for the analytes in the range of 83.5–114.8%. The limits of detection were in the range of 0.6–3.0 ng/mL. Relative standard deviations for intra- and interday precision were <4.68 and 6.08%, respectively. This simple, rapid, cost-effective and environmentally friendly method has been successfully applied to the analysis of synthetic colorants in 10 kinds of beverage samples.