Relevance and Standardization of In Vitro Antioxidant Assays: ABTS, DPPH, and Folin–Ciocalteu

Table 1

The range of concentration of antioxidants in assay solution (c_antioxidant).

Sample	cantioxidant range (μmol/L)
	DPPH				ABTS^+			FC
	MeOH	H2O	pH 5	pH 7.4	H2O	pH 5	pH 7.4
CA	8–40	8–40	8–40	3–15	8–40	8–40	8–40	3–15
CGA	6–30	6–30	6–30	2–10	6–30	6–30	4–20	6–30
GA	2.6–13	2.6–13	2.6–13	2.6–13	1.6–8.0	1.6–8.0	1.6–8.0	6–30
CTH	1.6–6.4	3–15	3–15	1.6–8	1.6–6.4	1.6–6.4	1.6–6.4	3–15
EGCG	1.4–7	1.4–7	1.4–7	0.8–4	1.4–7	0.8–4	0.8–4	3–15
AA	4–40	4–40	4–40	4–40	4–40	4–40	4–40	4–40
DHA	100–500	100–500	100–500	20–200	100–500	100–500	20–200	10–100
Trolox	5–35	5–35	5–35	5–35	5–35	5–35	5–35	5–35
FeSO4	—	—	—	—	—	—	—	20–120