β-Cyclodextrin coupled to graphene oxide supported on aminopropyl silica as a sorbent material for determination of isoflavones.

β-Cyclodextrin, coupled to graphene oxide supported on aminopropyl silica, was synthesized and characterized. This material was combined with microextraction by packed sorbent to act as the sample preparation step. The analytical method optimization was carried out by employing experimental design and had its figures of merit determined. The resulting linearity ranged from 1.0 to 200 μg/L for daidzein, from 2.0 to 200 μg/L for genistein, from 3.0 to 200 μg/L for formononetin, and from 2.0 to 200 μg/L for biochanin A with all R2 values above 0.993 and limit of quantification ranging from 0.5 to 1.5 μg/L. The accuracy ranged from 93.3 to 123.3%, and intraday and interday precision reported by the relative standard deviations were <16%. This work aimed to synthesize and evaluate cyclodextrins coupled to graphene-based sorbents to be used as a high sorption capacity and selective sorbent for sample preparation of complex matrices using microextraction techniques. The synthesized material kept the high absorption characteristic of graphene-based materials while maintaining the cyclodextrins' selectivity to extract the target analyte. Four isoflavones were determined in soy-based juice samples from the local market, confirming the excellent performance of the proposed method.