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A novel, simple, rapid, and non-expensive analytical method based on square wave voltammogram at Pt-microelectrode coupled with partial least square multivariate calibration was used for the simultaneous quantitation of thymol (THY) and carvacrol (CAR) in thyme and oregano essential oils. Results demonstrated that the multivariate calibration method successfully exploited the first-order advantage, rendering highly satisfactory quantitative figures (average recoveries not statistically different than 100%). Moreover, the results agree well with those obtained from the official analytical method. Last, the method's environmental sustainability was asserted using the AGREE metric, highlighting its eco-friendly nature. More importantly, the proposed analytical procedure does not require previous sample preparation or electrode surface modification. The results underscore the suitability of the method for determining THY and CAR in essential oils at low concentrations (LOD ~ 7.6 µM) with REP% below 5.6%, meeting the requirements of the green analytical chemistry. [ABSTRACT FROM AUTHOR]

In the present work, the oxidation mechanism of di- t -butyl-hydroxytoluene (BHT) was studied in an aqueous medium through different approaches to have a thorough vision of the physical chemistry: experiments with cyclic voltammetry (CV), quantum chemical calculations, and simulations of CV. Calculations of thermodynamic parameters, such as p K a and standard oxidation potential ( E ox °), were used to analyze and rationalize the CV experiments. Subsequently, different pathways of the mechanism were constructed, and the most thermodynamically favorable one was selected. Numerical simulations were then used to model this mechanism and compare it with the experimental data. The results show that the oxidation process is due to the coupled loss of an electron and a proton in the first instance, followed by an irreversible second electron-transfer process without loss of protons, mainly due to the adsorption of the products of the first oxidation on the electrode surface. The effect of different pH values on this oxidative mechanism was also analyzed, with alkaline pH of 12 as a medium where changes in reactivity were observed as the appearance of a new peak in the second voltammetric sweep, the interpretation of this peak is also provided., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)