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This paper describes the nonlinear behaviour of the acetaminophen-based uncatalysed Belousov–Zhabotinsky oscillator and its dynamics in the presence of ferroin as catalyst. The role of free metal ions as catalysts was examined and the results compared with those of corresponding complexed catalysts. Free metal ions were found to be sluggish with respect to the evolution of the oscillatory regime as compared to complexed ones. The effect was monitored of change of the ligand moiety of the catalyst complex on the oscillatory parameters. Since ethanol potentiates the hepatotoxicity caused by acetaminophen in vivo, it is thought to understand this interaction by virtue of causing perturbation of the acetaminophen-based oscillator with different concentrations of ethanol with and without ferroin as catalyst. Another dimension to the ethanol effect was examined by perturbation of the system with ethanol at different stages of the reaction so as to get an idea as to whether it is acetaminophen or some reactive intermediate generated in the reaction system which reacts with ethanol. Further, the ferroin-catalysed oscillator is taken as a prototype inorganic model of the acetaminophen–ethanol syndrome, as ferroin and hypobromous acid (HOBr) act as inorganic replacements for cytochrome P450 and nicotinamide adenine dinucleotide phosphate (NADPH) in alcohol metabolism.

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.

The present study introduces the use of phloroglucinol (1,3,5-trihydroxybenzene) as organic substrate in BZ reaction for the first time. This work has been carried out to assess the influence of initial reagent concentrations on the behavior of phloroglucinol–bromate–ferroin-based BZ reaction in a stirred batch reactor. The oscillations are followed by observing the change in redox potential. Different oscillatory parameters like induction time (tin), time period (tp), amplitude (A), frequency(v), and number of oscillations (N) show different changes with respect to changes in the initial concentrations of organic substrate, bromate and sulfuric acid, and these observations have been explained on the basis of FKN mechanism. The behavior of the aforesaid system in different aqueous acid media has been reported and it is found that sulfuric acid is the best medium for studying the system as it shows a wide oscillatory window compared to that of nitric acid. In phosphoric and perchloric acids the system does not show any oscillatory behavior. Activation parameters of the reaction have been derived by studying the reaction over a temperature range of 15 to 40 ± 0.1 °C. The effect of different catalysts on the oscillatory behavior has been studied and it is found that the system gives good oscillatory behavior with ferroin and Ce(III) whereas a poor response is seen when Mn(II) and Ce(IV) are used as catalysts.