Carbon nanotubes (CNTs) are widely used in electrochemical sensors due to their significant impact on the electroanalytical signal. However, there remain significant doubts regarding the origin of the improved electroanalytical response observed in CNT-based sensors, particularly concerning the precise role of CNTs in these systems. In particular, the origin of the electrochemical response is controversial, as it may be due to either electrocatalytic or non-electrocatalytic processes. The latter implies that the electroanalytical response is mainly governed by the mass transport phenomena within the porous CNT layer. This article briefly reviews the several comprehensive models based on the role of porosity (diffusion in a ‘thin-layer’) on the electrochemical behavior as well as on the electrocatalytic properties of CNTs to resolve conflicts arising from misinterpretations of the electroanalytical response of CNT-based sensors. However, even though there are some explanations and conclusions on this topic, they seem to be valuable for specific electroactive species, the type of CNTs and/or electrode architecture, the electrode surface, etc. Accordingly, general theories and conclusions are not yet defined, so different approaches to this topic are still needed, since the main phenomenological effects responsible for the nature of the electrochemical response of the electrodes modified with CNTs need to be determined in a rational way.

The aim of this work was to optimize the parameters of microwave extraction and to find the most suitable conditions for the application of extraction for Rosemary (Rosmarinus officinalis L.). The efficiency of the optimized method was compared with...

A new approach is presented to elucidate the phenomena that occur within a porous single-walled carbon nanotubes (SWCNTs) modified glassy carbon electrode (GCE) and that influence the electrochemical behavior of the modified electrode. By employing cyclic voltammetry, reverse pulse voltammetry, and double potential step chronoamperometry, insights into the structural changes in the electrochemical double layer and the mass transport regimes are gained. An analysis of the reduction of the electrochemically generated [Fe(CN)₆]³⁻ shows that the SWCNTs layer can be considered inactive. However, their pronounced influence on the electrochemical signal arises from their capacitive behavior. Furthermore, a novel criterion for distinguishing the mass transport domains is proposed, which allows the estimation of the points at which a change in the mass transport regime occurs. The results also show the role of the porous SWCNTs layer in preventing the expansion of the double layer as well as in the process of ion condensation in the Gouy-Chapman layer. Finally, the counterintuitive and unexpected voltametric behavior, such as the independence of the current peak heights from the ionic strength of the support, the parabolic dependence of the peak potential on the scan rates, and the occurrence of steady-state currents, are discussed.

It is well known that beer is more than 90% water, and therefore, water can be one of the main sources of fluoride in beers. With this in mind, the goal of the present study was to determine the mass concentration of fluoride in 53 beer samples. Using the recently published standard addition method in potentiometry, the fluoride content of 28 samples of the most consumed beers in the Republic of Croatia was determined. The remaining 25 beer samples tested came from so-called microbreweries, which together account for less than 10% of the Croatian market. Fluoride concentrations in light beers ranged from 49 to 180 μg L⁻¹, with a mean value of 95 ± 34 μg L⁻¹, and from 52 to 164 μg L⁻¹, with a mean value of 89 ± 29 μg L⁻¹ in dark beers. The mean value of fluoride content in beers from large producers was 100 ± 38 μg L⁻¹ and 89 ± 38 μg L⁻¹ in beers from small producers. All values are within the recommended range and thus do not pose a risk to human health. The statistical analysis showed no correlation between the mass concentration of fluoride and pH, i.e., alcohol content in beers.

Corrosion of metallic materials remains a persistent challenge due to its economic and safety implications. Although corrosion inhibitors are commonly used to limit degradation, many conventional formulations are toxic and have poor environmental compatibility, highlighting the need for sustainable alternatives. Bio-derived inhibitors, particularly those obtained from medicinal plants, have recently attracted attention for their potential to provide effective and environmentally benign corrosion protection. This study investigates Aloe vera extract, obtained by microwave-assisted extraction at various concentrations, as a green corrosion inhibitor for brass. Electrochemical measurements in 3% NaCl solution were used to evaluate its inhibitory performance. The results show a measurable reduction in corrosion rate in the presence of Aloe vera extract, demonstrating its ability to mitigate electrochemical degradation. This inhibitory effect is attributed to Aloe vera phytochemicals that adsorb onto the brass surface and form a protective barrier, suppressing corrosion processes. These findings support the feasibility of Aloe vera as a sustainable corrosion mitigation agent.