Determination of flavonoids in onion by HPLC-DAD

Objective To establish a high performance liquid chromatography coupled with a diode array detector(HPLC-DAD)method for the determination of major flavonoids in onion.Methods The chromatographic separation was performed in a SHIMADZU VP-ODS(250mm×4.6mm,5μm)column.The mobile phase was composed of water(A)and acetonitrile(B)using gradient elution.The column temperature was 30℃ with the flow rate 1.0ml/min,and UV absorbance was detected at a wavelength of 350 nm.Firstly,the flavonoids were identified by maximum UV absorption wavelength.Then,the rutin was used as a standard substance to establish the standard curve to determine the major flavonoids in onion.Results The HPLC-DAD method was established and validated to determine the major flavonoids.The calibration curve was linear in the range of 5.0~502.5μg/ml with good linearity(r=0.9995),repeatability(RSD4.1%),intra-day and inter-day precision(RSD3.3%),recovery(95.1% ~103.2%),limit of detection(0.3μg/ml),and limit of quantification(1.0μg/ml).The content of flavonoids in onion was 2.8 mg/g.Conclusion The method is convenient,feasible,and accurate for the determination of major flavonoids in onion.