Temporal Evolution of Catechol-Based Belousov–Zhabotinsky Chemical Oscillating System in Presence of Antioxidants

The perturbation effect of various antioxidants viz. ascorbic acid, glutathione, inosine, and N-acetylcysteine is monitored at 30 °C under stirred batch conditions and has a good sensitivity for the determination of these antioxidants. The addition of these antioxidants to the BZ mixture influences the oscillatory parameters to an extent that depends on the concentration of the antioxidant and higher concentrations as such were found to quench the oscillations. The experimental results have shown that the number of oscillations decreases on increasing the concentration of antioxidant. The detection limit is found to be less than 1.0 × 10−7mol L−1. In the case of glutathione, ascorbic acid, and N-acetylcysteine, a linear relationship (R2= 0.99) between time period and the [antioxidant] has been obtained over a concentration range of 0.025–0.6, 0.0125–1.0, and 0.00625–0.8 mol L−1with detection limits 6.925 × 10−5, 3.462 × 10−5, and 1.371 × 10−5mol L−1respectively whereas that for inosine a linear relationship (R2= 0.98) between amplitude and [antioxidant] has been obtained over a concentration range of 0.05–0.7 mol L−1and the detection limit is 1.385 × 10−4mol L−1. Further, interactions of these antioxidants with BZ reagents were confirmed by cyclic voltammetry, which paved the way for explaining the mechanisms involved.