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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.)

T-2 is one of the most potent cytotoxic food-borne mycotoxins. In this work, we have developed and characterized an electrochemical microfluidic immunosensor for T-2 toxin quantification in wheat germ samples. T-2 toxin detection was carried out using a competitive immunoassay method based on monoclonal anti-T-2 antibodies immobilized on the poly(methyl methacrylate) (PMMA) microfluidic central channel. The platinum wire working electrode at the end of the channel was in situ modified by a single-step electrodeposition procedure with reduced graphene oxide (rGO)-nanoporous gold (NPG). T-2 toxin in the sample was allowed to compete with T-2-horseradish peroxidase (HRP) conjugated for the specific recognizing sites of immobilized anti-T-2 monoclonal antibodies. The HRP, in the presence of hydrogen peroxide (H 2 O 2 ), catalyzes the oxidation of 4-tert-butylcatechol (4-TBC), whose back electrochemical reduction was detected on the nanostructured electrode at -0.15 V. Thus, at low T-2 concentrations in the sample, more enzymatically conjugated T-2 will bind to the capture antibodies, and, therefore, a higher current is expected. The detection limits found for electrochemical immunosensor, and commercial ELISA procedure were 0.10 μg kg -1 and 10 μg kg -1 , and the intra- and inter-assay coefficients of variation were below 5.35% and 6.87%, respectively. Finally, our microfluidic immunosensor to T-2 toxin will significantly contribute to faster, direct, and secure in situ analysis in agricultural samples., 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 this work, nanoporous gold (NPG) was prepared according to three different approaches, such as (i) anodization-electrochemical reduction (A-ECR, NPG A ), (ii) dynamic hydrogen bubble template (DHBT, NPG B ), and (iii) the combination of both methods (NPG A+B ). Field-emission scanning electron microscopy (FE-SEM) and cyclic voltammetry (CV) were used to investigate the structural morphology and the electrochemical behavior of the fabricated materials. The NPG A+B electrode showed a large amount of surface defects and/or edges, greater electrochemical surface area (2.5 cm 2 ), and increased roughness factor (35.4). Such outstanding features of the NPG A+B platform were demonstrated by the sensitive detection of methyl parathion (MP) in river water samples. CV results indicated nearly 25-fold, 6-fold, and 2.5-fold higher sensitivity for NPG A+B compared to that of bare Au, NPG A , and NPG B , respectively. Differential pulse voltammetry (DPV) results show a linear behavior in the MP concentration range of 5-50 ng mL -1 with a limit of detection (LOD) of 0.6 ng mL -1 and limit of quantification (LOQ) of 2.0 ng mL -1 . Besides, the NPG A+B sensor also revealed excellent selectivity towards MP detection in the presence of other interfering molecules or ions, reproducibility, and repeatability., (Copyright © 2021 Elsevier B.V. All rights reserved.)