3. Results
3.1. Validation of the HPLC method for analysis of the isoflavones
We adopted a simplified gradient reversed phase HPLC method
for the separation and determination of 12 isoflavones extracted
from soy germ. Fig. 1 showed the typical HPLC chromatograms of
the 12 isoflavones standard (A), and 12 isoflavones from untreated
soy germ (B) and vinegar soaked soy germ (C). Isoflavones all
absorb UV light, and UV detection may offer sufficient selectivity
and sensitivity for the determination of isoflavones (Yuan, Liu,
Peng, Wang, & Liu, 2009). The identifications of isoflavones were
achieved by comparing their retention time and spectra against
the known standards. As expected, the separation of 12 isoflavones
standard was achieved in the HPLC chromatograms (Fig. 1A), and
the calibration curves of the peak area (A) against the concentration
(C) for these isoflavone standards at 254 nm gave good linear
responses over a wide range (5–50 mg/L) of concentrations
(Table S1), indicating that this HPLC method was sensitive for
qualitative and quantitative determination of these isoflavones.