Novel assaying method for the accurate and rapid analysis of antioxidant total capacity based on hexachloroiridate(IV)

• Published in: Food chemistry 2024-09, Vol.451, p.139492-139492, Article 139492
• Main Authors: Liu, Yang, Zhang, Qiaoxia, Liu, Zhong, Wang, Xiyi, Tian, Hongwu, Shi, Liliang, Shi, Tiesheng
• Format: Article
• Language: English
• Subjects: Antioxidant; Hexachloroiridate(IV); IrRAC; Total antioxidant capacity
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2024.139492

We introduce a novel method, namely IrRAC, for assessing total antioxidant capacity utilizing the single electron oxidant hexachloroiridate(IV). This method leverages the 488 nm absorption band of [IrCl6]2− largely reducing interferences from antioxidants and their oxidation products. [IrCl6]2− is stable 6 h in phosphate-buffered saline (PBS) ensuring consistent and reproducible absorbance readings and rendering spectrophotometric determinations under physiological neutrality. Individual assessments of 23 antioxidants reveal a linear correlation between decreasing absorbance and increasing antioxidant concentration. When the IrRAC assay was compared with several established water-based methods, strong correlations were found. Importantly, [IrCl6]2− shows a minimal oxidation of non-antioxidative substances. Moreover, IrRAC performs well with synthetic antioxidant mixtures and real samples, highlighting that the nature of antioxidants dominates the assay without much disturbance. Commercial availability of K2[IrCl6] eliminates the need of pretreatment of the oxidant. Undoubtedly, the new method confers a compelling and cost-effective alternative to the existing electron transfer-based methodologies. •A novel method IrRAC for assessing total antioxidant capacity was developed.•Direct use of commercially available Ir(IV) reagent eliminates extra peparations.•The used absorption band around 488 nm of Ir(IV) minimizes interferencs.•IrRAC is strongly correlated with other relavent methods validating its reliability.•Wide applications to the TAC analysis of pure and real samples are anticipated.