Method validation by interlaboratory studies of improved hydrophilic oxygen radical absorbance capacity methods for the determination of antioxidant capacities of antioxidant solutions and food extracts.
Hydrophilic oxygen radical absorbance capacity (H-ORAC) is a method for evaluating antioxidant capacities of solutions of hydrophilic compounds. In this study, we improved the original method for H-ORAC determination, and evaluated the precision of the two improved methods (methods A and B) by interlaboratory studies using 5 antioxidant solutions and 5 food extracts as test samples. An interlaboratory study of method A, in accordance with the harmonized protocol, demonstrated satisfactory performance (intermediate precision relative standard deviations (RSD(int)) ranging from 4.6 to 18.8%; the reproducibility relative standard deviations (RSD(R)) ranging from 7.0 to 21.1%, and the HorRat values ranging from 0.40 to 1.93). However, methodological problems remained, and a further improved method, method B, was thus developed. An interlaboratory study of method B by 5 participating laboratories showed better intermediate precision and reproducibility (RSD(int) and RSD(R) ranging from 1.8 to 9.4%, and from 4.4 to 13.8%, respectively), and all HorRat values for the test samples were less than 1.3, suggesting good performance for the H-ORAC measurement.
National Food Research Institute, National Agriculture and Food Research Organization, 2-1-12 Kannondai, Tsukuba, Ibaraki 305–8642, Japan. nabej@affrc.go.jp
Jun
J
Watanabe
Tomoyuki
T
Oki
Jun
J
Takebayashi
Koji
K
Yamasaki
Yuko
Y
Takano-Ishikawa
Akihiro
A
Hino
Akemi
A
Yasui
D005502:Food; D016166:Free Radical Scavengers / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D038622:Internationality; D007753:Laboratories; D017382:Reactive Oxygen Species / Q000737:chemistry*; D012996:Solutions
D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D012996:Solutions