Identification of Major Flavone C-Glycosides and Their Optimized Extraction from Cymbidium kanran Using Deep Eutectic Solvents

~3. Materials and Methods 3.1. Chemicals, Reagents, and Equipment Whole dried C. kanran that had been cultivated in Jeju, Korea was provided by Amorepacific Corporation (Seoul, Korea). They were finely pulverized and kept at −20 ◦C until analysis. Compounds used for DES preparation are listed in Table 2, and their detailed information is summarized in Table S2. Analytical standards including vicenin-2 (≥98.0%), schaftoside (≥98.0%), and vicenin-3 (≥98.0%) were obtained from Alfa Biotechnology Co., Ltd. (Chengdu, Sichuan, China), while vitexin (95.0%) and isovitexin (98.0%) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Formic acid and trifluoroacetic acid were also from Sigma-Aldrich. HPLC-grade acetonitrile and water were obtained from J.T. Baker (Phillipsburg, NJ, USA). An ultrasonic bath (Powersonic 410) and a heating magnetic stirrer were obtained from Hwashin Technology (Seoul, Korea) and VELP Scientifica (Usmate, Italy), respectively.