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This study is aimed to develop an electroanalytical methodology using a boron-doped diamond electrode (BDD) associated with experimental design in order to determine simultaneously and selectively carbendazin (CBZ) and fenamiphos (FNP) pesticides. In previous studies oxidation peaks were observed at 1.10 V (CBZ) and 1.20 V (FNP), respectively, with characteristics of irreversible processes controlled by diffusion of species (in pH 2.0 (CBZ) and pH 3.5 (FNP)) using a BR buffer 0.1 mol L−1 as support electrolyte. The differences between the potentials for both pesticides, (about 100 mV) indicate the possibility of selective determination of FNP and CBZ. However, employing an equimolar mixture of analytes, the peaks overlap to form a single oxidation peak. Thus, we used a 34 full factorial design with four parameters to be analyzed in three levels, in order to obtain the optimized parameters for the separation of the peaks. The best separation conditions were pH 5.0, square wave frequency of 300 s−1, pulse amplitude of 10 mV and scan increment of 2 mV. These parameters were used to obtain the calibration curves of CBZ and FNP. For CBZ the analytical curve was obtained in the concentration range of 4.95×10−6 to 6.90×10−5 mol L−1 with good sensitivity and linearity (0.175 A/mol L−1 and 0.999, respectively). The limits of detection (LOD) and quantification (LOQ) were 1.6×10−6 mol L−1 and 5.5×10−6 mol L−1, respectively. For FNP the linear concentration interval was 4.95×10−6 to 3.67×10−5 mol L−1, with a sensitivity of 0,207 A/mol L−1 and linearity of 0.996. The LOD and LOQ were 4.1×10−6 mol L−1 and 13.7×10−6 mol L−1, respectively. Using these experimental conditions it was possible to separate the oxidation peaks of CBZ (Ep=1.08 V) and FNP (Ep=1.23 V). The electroanlytical method was applied in lemon juice samples. The recovery values were 110.0 % and 92.5 % for CBZ and FNP, respectively. The results showed that the developed method is suitable for application in foodstuff samples. [ABSTRACT FROM AUTHOR]

The anodic voltammetric behavior of 4-Nitrophenol on a Boron-doped diamond electrode in aqueous solution has been studied using square wave voltammetry. After optimization of the experimental conditions, that model molecule was analyzed in pure water solutions using a Britton-Robinson buffer with pH 6.0 as the supporting electrolyte. Oxidation occurs at 1.0 V vs. Ag/AgCl in an irreversible two-electron process controlled by adsorption of the species. The detection limit (DL) obtained was 2.8 mug L-1. This result was comparable to that obtained from reduction of the molecule at -0.8 V vs. Ag/AgCl under the same experimental conditions (DL = 4.2 mug L-1). Both DL values are within the limits required by the legislation for drinking water (30 mug L-1). The combination of square wave voltammetry and diamond electrodes has proved to be an interesting and desirable alternative for the analytical determination of organic molecules.

In this work, the electrochemical behavior of the glycosylated flavonoid kaempferitrin was studied, and an electroanalytical methodology was developed for its determination in infusions of Bauhinia forficata using a boron-doped diamond electrode (BDD). The electrochemical behavior of the flavonoid was studied by cyclic voltammetry, and two irreversible oxidation peaks at 0.80 and 1.0 V vs Ag/AgCl were observed. The influence of the pH on the voltammograms was examined, and higher sensitivity was found at pH 7.0. The electrochemical process corresponding to peak 1 at 0.80 V is predominantly diffusion-controlled, as the study shows at varying scan rates. An analytical plot was obtained by square wave voltammetry at optimized experimental conditions (frequency = 100 s -1 , amplitude = 90 mV, and step potential = 8 mV) in the concentration range from 3.4 μmol L -1 to 58 μmol L -1 , with a linearity of 0.99. The limit of detection and limit of quantification values were 1.0 μmol L -1 and 3.4 μmol L -1 , respectively. Three samples of Bauhinia forficata infusions (2 g of sample in 100 mL of water) were analyzed, and the KF values found were 5.0 × 10 -4  mol L -1 , 3.0 × 10 -4  mol L -1 , and 7.0 × 10 -4  mol L -1 , with recovery percentages of 98 %, 106 % and 94 %, respectively. Finally, experiments were performed with two other flavonoids (chrysin and apeginin) to compare and propose an electrochemical oxidation mechanism for kaempferitrin, which was supported by quantum chemical calculations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In recent years, there has been an increasingly growing interest regarding the use of electrochemical advanced oxidation processes (EAOPs) which are considered highly promising alternative treatment techniques for addressing environmental issues related to pollutants of emerging concern. In EAOPs, electrogenerated oxidizing agents, such as hydroxyl radical (HO • ), can react non-selectively with a wide range of organic compounds, degrading and mineralizing their structures to unharmful molecules like CO 2 , H 2 O, and inorganic ions. To this date, a broad spectrum of advanced electrocatalysts have been developed and applied for the treatment of compounds of interest in different matrices, specifically aiming at enhancing the degradation performance. New combined methods have also been employed as alternative treatment techniques targeted at circumventing the major obstacles encountered in Fenton-based processes, such as high costs and energy consumption, which still contribute significantly toward inhibiting the large-scale application of these processes. First, some fundamental aspects of EAOPs will be presented. Further, we will provide an overview of electrode materials which have been recently developed and reported in the literature, highlighting different anode and cathode structures employed in EAOPs, their main advantages and disadvantages, as well as their contribution to the performance of the treatment processes. The influence of operating parameters, such as initial concentrations, pH effect, temperature, supporting electrolyte, and radiation source, on the treatment processes were also studied. Finally, hybrid techniques which have been reported in the literature and critically assess the most recent techniques used for evaluating the degradation efficiency of the treatment processes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In order to obtain higher agricultural yields, the use of chemical substances has been increased to prevent the proliferation of pests, as well as ensuring durability in the storage of the food produced. Such substances are known as pesticides that may well present risks to human health and the environment. In the presence of metal ions, these substances can interact forming new species with different characteristics. Carbendazim (MBC) is an example of a harmful pesticide, which has atoms of nitrogen and oxygen in its structure that can form complexes with metal ions. Thus, in this work has studied the interaction between the copper (II) metal ion and carbendazim and its formation in natural water. The Cu-MBC complex showed a reduction peak of 0.007 V and an oxidation peak of 0.500 V, with characteristics of a quasi-reversible process under a glassy carbon electrode. By anodic stripping voltammetry, a different behavior was observed in the interaction of copper and carbendazim in ultrapure water and Billings dam water; however, it was possible to observe the complex in both samples. Carbendazim in the presence of the metal shows lower oxidation potential value, indicating the influence of the metal on the electrochemical response of the pesticide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A simple, rapid and effective analytical method based on fluorescence spectroscopy for the determination of coumarin in pharmaceutical formulations without pre-treatment or pre-concentration step was development. Coumarin had maximum excitation and emission at 310 nm and 390 nm, respectively. Optimum conditions for the detection of coumarin were investigated. Under optimized conditions, we observed a linear behavior for the sign of coumarin in the concentration range of 2.5 × 10(-6) to 1.0 × 10(-4) mol L(-1), with linearity of 0.998 and sensitivity of 2.9 × 10(10) u.a/mol L(-1). The proposed method was validated in terms of accuracy, precision and specificity of coumarin using the standard addition and external calibration. It was noted that the results support (P<0.05), indicating that the matrices were not an interference in the determination of coumarin by fluorescence spectroscopy. The results were favorable compared with those obtained by reference chromatographic methods., (© Springer Science+Business Media, LLC 2010)

Potentially useful stead-state fluorimetric technique was used to determine the critical micellar concentrations (CMC(1) and CMC(2)) for two micellar media, one formed by SDS and the other by SDS/Brij 30. A comparative study based on conductimetric and surfacial tension measurements suggests that the CMC(1) estimated by the fluorimetric method is lower than the value estimated by these other techniques. Equivalent values were observed for SDS micelles without Brij 30 neutral co-surfactant. The use of acridine orange as fluorescent probe permitted to determine both CMC(1) and CMC(2). Based on it an explanation on aspects of micelle formation mechanism is presented, particularly based on a spherical and a rod like structures.

The microenvironment formed by lauroyl and stearoyl derivatives of chitosan in solution has been studied using two fluorescent probes, pyrene and nabumetone. Existence or not of microdomains formed by polymolecular associations, the inherent hydrophobicity of them in aqueous solution, and the influence of degree of substitution (DS) of derivatives were investigated by emission properties of pyrene and strengthened by the photophysical behavior of nabumetone. Additionally, the ratio between the fluorescence intensities of first (approximately 372 nm) to the third (approximately 384 nm) bands of the emission spectrum of pyrene was used to determine the critical aggregation concentration (CAC). In a previous work, it was already reported the characterization of chitosan derivatives by three spectroscopic techniques ((13)C-NMR, (1)H-NMR and infrared), as well as data on the solubility and swelling-index of them. In addition of that, the new results show that the investigated lauroyl and stearoyl derivatives of chitosan are expected to be potential models for applications in the medical field.