HPLC analysis of the dehydroascorbic derivatives was performed on a Hypersil ODS column (250 × 4 mm) with MeOH/phosphate buffer (1:1 v/v),pH 7.4, 80 mM as mobile phase (flow ) 0.6 mL/min), and fluorescence detection (excitation, 360 nm; emission, 440 nm.