An optimised method for the rapid measurement and calculation of radical scavenger profiles in plant extracts by HPLC

An assay for the measurement of antiradical activity profiles of free radical scavengers (sometimes called antioxidants) in plant extracts was optimised on a modular instrument to obtain rapid and precise results. The first step of a run was separation by RPHPLC recorded with a direct absorbance detector, followed by a post-column reaction with a radical form of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+). Then, the effect of colour bleaching of ABTS+ was measured on a second absorbance detector (indirect detection). A comparison of the two signals distinguished the analytes with antiradical activity.Improvements in technical features, namely the minimisation of reaction volume and the use of precise high-pressure pumps enabled both the detector signals to be precisely matched without significant loss of separation efficiency, even in complex chromatograms.