Liquid–Liquid Microextraction Based on Acid–Base-Induced Deep Eutectic Solvents for Determination of β-Carotene and Lycopene in Fruit Juices

An uncomplicated, valid, and convenient way for detection of lycopene and β-carotene in fruit juice samples using acid–base-induced deep eutectic solvent (DES) liquid-liquid microextraction (DES-ABLLME) prior to HPLC was developed. The ternary fatty acid DESs were prepared by C 9 :C 10 :C 11 (2:1:1), which serve as hydrogen bond donors and hydrogen bond acceptors synchronously. In extraction procedure, NH 3 ·H 2 O was used as the emulsifier and reacted with DESs with a milk solution, which can significantly increase the extraction efficiency. HCl was used as the de-emulsifier, which could break the state of emulsification. At optimum conditions, the calibration graphs were linear in the concentration range from 0.1 to 100 μg mL −1 for lycopene and from 0.025 to 5.00 μg mL −1 for β-carotene. The limits of detection (LODs) were 0.05 and 0.002 μg mL −1 for lycopene and β-carotene, respectively. The RSD values were varied from 1.3 to 4.1%. Finally, the proposed method was applied to analyze β-carotene and lycopene in fruit juices.