Combined use of ionic liquid micelles and natural carbon dots@deep eutectic solvent (CDs@DES) to extract and separate flavonoids and terpenoids from Ginkgo biloba leaves

For the first time, two kinds of green solvents including ionic liquid (IL) and deep eutectic solvent (DES) were combined for achieving flavonoids and terpenoids simultaneously from Ginkgo leaves. They were applied in the form of micelles and the complex with natural carbon dots (CDs) as extraction and separation mediums, respectively. Especially, the latter was prepared from the lignocellulosic residue of Ginkgo leaves after extraction, which achieved the comprehensive utilization of natural resources. Critical micelle concentrations (CMC) of the IL were determined as 4.70–5.38 in the range from 5 to 45 °C, and the main particle size of CDs was found between 20 and 25 nm. After comprehensive characterization on them, a biphasic system composed of IL micelles and CDs@DES was constructed, with the former in the upper layer and the latter in the lower layer. Then it was successfully applied for obtaining flavonoids and terpenoids from the leaves of Ginkgo biloba with extraction efficiency of 96.2 % and 93.2 % respectively, which were analyzed by liquid chromatography-mass spectrum (LC-MS). Moreover, the IL and DES could be repeatedly used through the post-treatment.