Liquid chromatographic–mass spectrometric determination of genistin and daidzin in soybean food samples after accelerated solvent extraction with modified content of extraction cell

A newly elaborated accelerated solvent extraction (ASE) procedure allowed more accurate (<2%) and precise (<5–8% rel.) HPLC/UV/MS determination of isoflavones in different kinds of food made from soybean (products of ecological agriculture), i.e. soy farina, soy meat granulate, soy meat laminae, soy meat bits, Protmix and EKO-B1. The on-column limits of detection (LOD) for daidzin/genistin were 1.2/1.6 fmol for the signal-to-noise ratio S/N=3 and 1–3 fmol for daidzein, genistein, formononetin, biochanin A and ononin, respectively. Final concentrations of daidzin in soybean foods fluctuated between 30 and 60 (mu)g/g of dry matter (DM). Significantly higher concentrations of genistin (between 60 and 130 (mu)g/g DM) were found in the soybean foods.