Analytical Sciences

Abstract − Analytical Sciences, 30(7), 717 (2014).

Applicability of the DPPH Assay for Evaluating the Antioxidant Capacity of Food Additives – Inter-laboratory Evaluation Study –
Tomoko SHIMAMURA,*1 Yoshihiro SUMIKURA,*1 Takeshi YAMAZAKI,*2,*3 Atsuko TADA,*2 Takehiro KASHIWAGI,*1 Hiroya ISHIKAWA,*4 Toshiro MATSUI,*5 Naoki SUGIMOTO,*2 Hiroshi AKIYAMA,*2 and Hiroyuki UKEDA*1
*1 Faculty of Agriculture, Kochi University, Monobe B-200, Nankoku, Kochi 783-8502, Japan
*2 National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo 158-8501, Japan
*3 Faculty of Human Life Sciences, Jissen Women’s University, 4-1-1 Osakaue, Hino, Tokyo 191-8510, Japan
*4 International College of Arts and Sciences, Fukuoka Women’s University, 1-1-1 Kasumigaoka, Higashi, Fukuoka 813-8529, Japan
*5 Faculty of Agriculture, Graduated School of Kyushu University, 6-10-1 Hakozaki, Higashi, Fukuoka 812-8581, Japan
An inter-laboratory evaluation study was conducted in order to evaluate the antioxidant capacity of food additives by using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Four antioxidants used as existing food additives (i.e., tea extract, grape seed extract, enju extract, and d-α-tocopherol) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) were used as analytical samples, and 14 laboratories participated in this study. The repeatability relative standard deviation (RSDr) of the IC50 of Trolox, four antioxidants, and the Trolox equivalent antioxidant capacity (TEAC) were 1.8 – 2.2%, 2.2 – 2.9%, and 2.1 – 2.5%, respectively. Thus, the proposed DPPH assay showed good performance within the same laboratory. The reproducibility relative standard deviation (RSDR) of IC50 of Trolox, four antioxidants, and TEAC were 4.0 – 7.9%, 6.0 – 11%, and 3.7 – 9.3%, respectively. The RSDR/RSDr values of TEAC were lower than, or nearly equal to, those of IC50 of the four antioxidants, suggesting that the use of TEAC was effective for reducing the variance among the laboratories. These results showed that the proposed DPPH assay could be used as a standard method to evaluate the antioxidant capacity of food additives.