QuEChERS method for the extraction of isoflavones from soy-based foods before determination by capillary electrophoresis-electrospray ionization-mass spectrometry

This article reports the development of a modified approach of the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) methodology for the extraction of naturally occurring substances from solid soy-based products. The use of this methodology offers advantages such as simplicity and ease of use, especially taking into account the complexity of food matrices. Here, capillary electrophoresis coupled with electrospray ionization mass spectrometry (CE-ESI-MS) was applied for the separation and quantification of isoflavones in soy products. Because of the importance of the different forms of isoflavones as regards their biological activity, a method that would permit both aglycones and the glycoside forms of isoflavones to be determined was developed. The proposed method was successfully applied to the analysis of the glycosylated forms glycitin, daidzin and genistin, and the aglycones formononetin, biochanin A, glycitein, daidzein, and genistein in commercially available soy biscuit samples. The parameters evaluated for the validation of the method developed included the linearity of the calibration plots, the detection and quantification limits, the existence of matrix effect(s), repeatability, reproducibility and recovery. The results of the validation process revealed that the proposed method is a possible alternative in routine analysis of isoflavones in food matrices. (c) 2012 Elsevier B.V. All rights reserved.