Ionic Liquid-based Ultrasonic-Assisted Extraction Coupled with HPLC for Sensitive Determination of Flavonoids in Mulberry Leaves

An analytical method to determine flavonoids such as morin hydrate,quercetin and kaempferol in mulberry leaves was proposed using ultrasonic-assisted extraction coupled with HPLC.The extraction solvent used was 1-butyl-3methylimidazolium chloride([BMIM]Br).The chromatographic separation was performed on Phenomenex C18 column(250 mm × 4.6 mm,5 μm) using a mobile phase made up of methanol and 0.1% phosphoric acid at a flow rate of 1.0 mL/ min by gradient elution.The detection wavelength and column temperature were set as 365 nm and 34 ℃,respectively.This method showed good linearity in the range of 0.0065–130 μg/mL(r = 0.9999) for morin hydrate,of 0.0064–128 μg/mL(r = 0.9999) for quercetin,and of 0.0042–84 μg/mL for kaempferol.The limit of detection,LOD,(RSN = 3) of this method was 0.99,1.31 ng/mL and 0.64 ng/mL for morin hydrate,quercetin and kaempferol,respectively.Average recoveries ranging 90.00% to 95.31% were obtained for these three flavonoids(n = 3).This method was simple,fast,accurate,sensitive,cheap and environment-friendly and could provide a scientific way to determine flavonoids in mulberry leaves.