Development of an automated HPLC- DAD- radical scavenging detection system with on-line sample enrichment

Abstract

An HPLC-DAD-radical scavenging detection system for the rapid on-line identification of antioxidants in complex plant extracts has been developed in our lab [1–3]. To increase its sensitivity and to further decrease the manpower input an additional automated on-line sample enrichment system is presented. With this system injection, enrichment and separation is controlled by computer and by connection with an ABTS radical solution pump detection and identification of antioxidants in fruit juices, vegetables, and processed foods is possible. Trap breakthrough and reproducibility of retention time and area were calculated. The maximum injection volume is 200µL, the intraday day variability (n=3) of retention time and area varied from 0.1%-2.1% and from 0.5%-16%. Within days a RSD (n=3) of retention time and peak area of 0.1%-2.2% and from 1.2% to 28% was observed, respectively. By means of a splitter, a mass spectrometer can be added for structure elucidation. Using this method, various samples were investigated. Their profiles revealed more radical scavenging compounds than previously found because of the larger injection volume and sample enrichment. The fingerprints allow following the fate of antioxidants during processing or storage, as well as variations between batches of the same fruits or commercial food products. Automated data processing will be pursued.