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A real time evaluation method for the ex vivo antioxidative effect in rat blood after administration of ascorbic acid (ASA) is described. The antioxidative effect in small amounts of samples (0.5 μL) could be measured by hyphenated semi-micro flow injection analysis-chemiluminescence detection and microdialysis methods. Antioxidative effects of blood microdialysates obtained from rats administered 50 mg/kg ASA through different routes (intravein: i.v., intraperitoneal: i.p. and per os: p.o.) were evaluated. The increased effects were maintained up to 360 min after administration. The AUC 0-360 (antioxidative effect % × min) were 16,260 ± 1739 (i.v.), 12,873 ± 2152 (i.p.) and 6668 ± 2251 (p.o.). Additionally, ASA was determined to be the source of the microdialysate antioxidative effect by diminishing its effect with ascorbic acid oxidase. Furthermore, the concentration of ASA in the microdialysate was correlated with the antioxidative effect (r = 0.915)., Food Chemistry, 134(1), pp.546-552; 2012

A semi-micro flow injection analysis (SMFIA) method for evaluation of quenching effect of food additive antioxidants or health foods on peroxynitrite (ONOO(-)) is described. The injected sample was carried with phosphate buffer containing NaNO(2), mixed with a trigger solution to generate ONOO(-) and then detected CL generated after mixing with luminol solution. Selective chemiluminescence caused by ONOO(-) in this generation system was confirmed by catalase treatment. Ascorbic acid (ASA), Trolox and ascorbyl palmitate (ASP) were used as food additive antioxidants. EC(50) values of ASA, Trolox and ASP were 2.6, 6.4 and 43 µg/mL, respectively. The amount of reagents required for an assay by this SMFIA system could reduce the time by a third compared with the conventional method previously reported. Furthermore, as an application of the proposed method, the quenching effect of commercially available Noni (Morinda citrifolia) juices was evaluated.