Ascorbic acid and choline chloride: A new natural deep eutectic solvent for extracting tert-butylhydroquinone antioxidant

A novel natural deep eutectic solvent (NADES) based on choline chloride and ascorbic acid (vitamin C) was synthesized for the first time. This NADES is green since choline chloride and vitamin C are frequently used food additives. And ultrasonic-assisted liquid-liquid microextraction technique was employed using this NADES for the extraction tert-butylhydroquinone from edible oils, which was coupled with the HPLC-UV analysis. The experimental conditions of liquid-liquid microextraction were optimized, and a near 100% extraction efficiency was obtained. The liquid-liquid microextraction combined HPLC-UV method for the determination of tert-butylhydroquinone showed good recovery (i.e., 96.1-109%) and precision (i.e., the relative standard deviation for intra-day and inter-day precision were 1.8% and 2.9%, respectively), as well as a lower limit of detection (i.e., 0.02 mg/kg). This method was successfully applied in the determination of tert-butylhydroquinone in 12 kinds of edible oils, and the results were close to those of conventional liquid-liquid extraction with methanol. Importantly, this novel NADES (choline chloride + vitamin C) exhibited an excellent protection ability for tert-butylhydroquinone during the extraction process, which indicated that this NADES could be used as an excellent extraction medium for easily oxidized compounds in complicated samples. (C) 2018 Elsevier B.V. All rights reserved.