Determination of quercetin aglycone in Flos Sophorae Immaturus extract of (Sophora japonica L.) by High Performance Liquid Chromatography
The research has established a method to directly extract and determine free quercetin (aglycone form) from Flos Sophorae Immaturus methanol extract by using a simple HPLC method. Conducting experiment with system HPLC Agilent 1260 Infinity, reverse column ZORBAX SB-C18 (temperature 25oC), flow rate 0.5 ml/min, average pressure 30 and 35 bar, and diode array detector (DAD), we found that these parameters is suitbale: λmax = 370 nm, injection volume is 20 µl, analysis time 16 minutes, mobile phase (% volume) consists of methanol (15%), acetonitril (20%) and solvent C (65%, contains 1% acetic acid, methanol, acetonitril and H2O, 40%, 15% and 45% respectively. After using a combination of irocratic elution and standard addition, retention time of free quercetin in Flos Sophorae Immaturus methanol extract has found to be 8.84 ± 0,05 (min). Relative standard deviation (RSD) of retetion time, peak area and peak height have been less than 1%, this results have indicated that the proposed method has fullfilled the validation parameters such as selectivity/specitifity, precision/repeatability. This study provided useful information for screening activity of quercetin by using different methods.