Inter-laboratory Validation Study of a Singlet Oxygen Absorption Capacity Assay Method for Determining the Antioxidant Capacities of Antioxidant Solutions and Food Extracts

Abstract

Singlet oxygen absorption capacity (SOAC) is an assay method used to evaluate the singlet oxygen quenching capacity. We evaluated the precision of the SOAC assay method in an inter-laboratory validation study using 3 antioxidant solutions and 3 food extracts. This study involved 14 participating laboratories, with data sets from 8 successfully participating laboratories subjected to statistical analysis. In accordance with the harmonized protocol, this study showed that the intermediate precision relative standard deviation (RSD_int) and the reproducibility relative standard deviation (RSD_R) ranged from 3.4 to 9.9%, and from 6.2 to 14.0%, respectively, and the HorRat values ranged from 0.87 to 1.97. Therefore, the SOAC assay method was validated by this inter-laboratory study in accordance with the internationally harmonized protocol.