Analytical Sciences

Improvement and Interlaboratory Validation of the Lipophilic Oxygen Radical Absorbance Capacity: Determination of Antioxidant Capacities of Lipophilic Antioxidant Solutions and Food Extracts

Jun WATANABE,* Tomoyuki OKI,** Jun TAKEBAYASHI,*** Hiroshi YADA,* Manabu WAGAKI,* Yuko TAKANO-ISHIKAWA,* and Akemi YASUI*

*National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba 305-8642, Japan
**National Agricultural Research Center for Kyushu Okinawa Region, National Agriculture and Food Research Organization, 2421 Suya, Koshi, Kumamoto 861-1192, Japan
***National Institutes of Biomedical Innovation, Health and Nutrition, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku, Tokyo 162-8636, Japan

A lipophilic oxygen radical absorbance capacity (L-ORAC) assay is an evaluation of the antioxidant capacity of solutions of lipophilic compounds. The concentrations of fluorescein, radical generator, and Trolox standard solutions were optimized to improve the precision of the assay. An interlaboratory study using two antioxidant solutions and three food extracts as test samples conducted in accordance with harmonized protocol demonstrated satisfactory L-ORAC measurements; the intermediate precision relative standard deviations (RSD_int) ranged from 7.0 to 16.7%, the reproducibility relative standard deviations (RSD_R) ranged from 14.8 to 19.4%, and the HorRat values ranged from 1.35 to 1.78.

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