Study Of Microwave-assisted Extraction Of Flavonoids By Ionic Liquids

Ionic liquids（ILs） is a designable and green solvent with a low vapor pressure, strong solubility and environmental friendly. When the ILs was used as the extraction solvents and combined with microwave-assisted extraction method（MAE）, a new method of ionic liquids based microwave-assisted extraction（ILs-MAE） was developed to extract the flavonoid from plants. This paper investigated the extract apigenin and luteolin by ILs-MAE. The research in the paper were included:1.The optimum extraction conditions were confirmed. The optimum extraction conditions of flavonoids were studied by single factor experiments and response surface design experiments. The optimized conditions of extraction apigenin and luteolin were concluded, respectively. For apigenin, 10 mL of 0.54 mol/L of [C₈mim]Br solution was used to extract apigenin from celery powder under the microwave power of 600 W and extraction time of 10 min, the extraction yield of apigenin was up to 79.83%. For luteolin, 14.60 m L of 1.00 mol/L [C₁₀mim]Br solution was used to extract luteolin from peanut shells powder under the extraction temperature of 85℃ and extraction time of 12 min, the extraction yield of luteolin reached 80.11%.2. ILs and MAE were compared with the conventional organic solvents and other extraction methods on the extraction yield, respectively. The results showed ILs showed a excellent extraction yield than the conventional organic solvents and the MAE had an advantage than other extraction technology.3. The extraction mechanism. The 1H NMR was used to investigate the interactions between apigenin and [C₈mim]Br. This technology mainly to confirm whether there is intermolecular hydrogen bonding between apigenin and [C₈mim]Br. The results showed that no or few intermolecular hydrogen bonding between apigenin and [C₈mim]Br.4. The extraction kinetics. The kinetics of extraction luteolin from peanut shells was investigated on the basis of the Fick’s Second Law. The kinetics parameters of luteolin in peanut shells by ILs-MAE were calculated to provide the theory foundation for the technical designing and operational condition of luteolin extraction optimization.