(J. Sep. Sci. 2014, 37 (24), 3641–3648)
This paper describes an approach to simultaneously evaluate the antioxidant power of a component versus radicals, and to identify it in two vegetal matrixes. This work includes the development of a new material, i.e. functionalized graphene quantum dots, able to adsorb radicals, thus facilitating their interaction between antioxidants contained in complex matrices. This fact is demonstrated by applying the method to plant extracts. Separation is performed with and without a preliminary exposure of the sample to specific free radicals on a ‘functional’ graphene quantum dots surface, which facilitates reaction between free radicals and potential antioxidants. The difference in chromatographic peak areas is used to identify potential antioxidants. The structure of the antioxidants in two samples (Radix Scutellariae and Licorice skin) is identified using MS/MS is and compared with standards. The approach is interesting and potentially useful. The electrochemical impedance spectroscopy was successfully employed to monitor the electrochemical characteristics of the complex plant extract screening system for the first time. The new screening approach can also be widely used for the detection and identification of antioxidants in other complex samples.