Abstract
A rapid HPLC method was developed for determination of isoflavones in soybean. Twelve isoflavones were resolved within 15 min by using a Vydac 201TP54 C18 column and a mobile phase of acetonitrile (A) and water (B) with the following gradient elution: 8% A and 92% B initially, increased to 10% A in 2 min, 12% A in 3 min, 22% A in 10 min, 23% A in 11 min, 35% A in 12 min, 50% A in 13 min, maintained for 3 min, and returned to 8% A in 20 min. The flow rate was 2 mL/min with column temperature at 35°C and detection at 262 nm. Formononetin was found to be a suitable internal standard for quantification. A solvent system of acetone–0.1 mol/L hydrochloric acid (5:1, v/v) was used for extraction of isoflavones from soybean, and the recoveries ranged from 64–87%. The malonylglucosidic type of isoflavones was present in the largest amount, while the acetylglucosidic type showed the lowest level.
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