Determination of daidzein and genistein in soybean and its waste by matrix solid-phase dispersion extraction and HPLC

Abstract

Matrix solid-phase dispersion (MSPD) extraction and HPLC have been used for determination of daidzein and genistein in Iranian soybean and its waste. For extraction of these compounds, the type of sorbent, the ratio of sorbent to sample, and the type and volume of elution solvent and its pH were studied. The best recoveries were obtained with a ratio 2:1 of silica gel to sample and 12 cm3 methanol at pH 3. Optimized mobile phase composition for HPLC analysis of these compounds was φ(H2O) = 0.45, φ(MeOH) = 0.54, φ(THF) = 0.01 adjusted to pH 4 by use of phosphate buffer. Limit of detection and linear dynamic range for daidzein and genistein were 0.016, 0.052, 0.016–132, and 0.052–146 μg/g. Recoveries of daidzein and genistein from soybean and its waste were 84–95%. Concentrations of daidzein in soybean and its waste were 39.1 and 22.2 μg/g, respectively; respective concentrations of genistein were 103.3 and 19.7 μg/g.