High-Performance Liquid Chromatography Coupled with Coulometric Array Detection of Electroactive Components in Fruits and Vegetables: Relationship to Oxygen Radical Absorbance Capacity
An HPLC procedure utilizing reversed-phase chromatography coupled with a coulometric array detection system was developed for the characterization of overall antioxidant status in fruits and vegetables. The method was reliable and sensitive (20 pg to 1 ng detection limit) and can also be used to identify and simultaneously quantify multi-antioxidants including vitamin C, glutathione, phenolic acids, and flavonoids in fruits and vegetables. Each fruit and vegetable aqueous extract showed an unique distribution of chromatographic peaks that could serve as a “fingerprint” for the fruit or vegetable. A significant positive linear correlation was demonstrated in fruit and vegetable aqueous extracts between the total antioxidant activities determined by using oxygen radical absorbance capacity (ORACROO•) assay and the electrochemical data generated from the coulometric array detectors. From these data, the ORACROO• assay appears to be a valid and useful procedure for measuring total antioxidant activity in extr...