Hugo B. Suffredini

DFT and electrochemical studies on nortriptyline oxidation sites.

A study on the possible sites of oxidation and epoxidation of nortriptyline was performed using electrochemical and quantum chemical methods; these sites are involved in the biological responses (for example, hepatotoxicity) of nortriptyline and other similar antidepressants. Quantum chemical studies and electrochemical experiments demonstrated that the oxidation and epoxidation sites are located on the apolar region of nortriptyline, which will useful for understanding the molecule’s activity. Also, for the determination of the compound in biological fluids or in pharmaceutical formulations, we propose a useful analytical methodology using a graphite-polyurethane composite electrode, which exhibited the best performance when compared with boron-doped diamond or glassy carbon surfaces.

Reaproveitamento de óxidos de manganês de pilhas descartadas para eletrocatálise da reação de redução de oxigênio em meio básico

The oxygen reduction reaction was studied in alkaline media using manganese oxides obtained from spent batteries as electrocatalysts. Three processes were used to recover manganese oxides from spent batteries. The particles obtained were in the range from 8 to 11 nm. The electrochemical experiments indicated a good electrocatalytic activity toward oxygen reduction using the different samples and showing approximately a direct transference of 4 electrons during the process. Even though all the processes were efficient, the best result was observed for the prepared sample using reactants of low cost.

Ferrocene partition calculation in a biodiesel/water interface using electrochemical methods

This work is a continuation of previous studies concerning the behaviour of ferrocene in a mixture of two insoluble liquids. In this paper, the system reached partition equilibrium after approximately 175xa0min. Electroanalytical studies were executed, and a high reproducibility was observed in a range of concentrations from 2 to 14u2009×u200910−5xa0molxa0L−1 of ferrocene that escaped from the oil to the aqueous phase. Because ferrocene most likely occurs only in the monomeric form in both the oil and aqueous phases, it was possible to predict a partition coefficient (log P(oil/water)) of ferrocene of approximately 2.4.

Poly-L-Arginine-Modified Boron-Doped Diamond and Glassy Carbon Electrodes for Terbutaline Sulfate Detection

This work describes the electro polymerization of a poly-L-arginine film onto boron-doped diamond (BDD) electrode and glassy carbon electrode (GCE) surfaces. The morphological and electrochemical properties of the modified electrodes were studied by atomic force microscopy and electrochemical methods, and their potential for terbutaline sulfate (TBS) detection was determined by voltammetry and chronoamperometry techniques. Our results demonstrate that the electrochemical surface area of both uncoated-bare electrodes (GCE e BDD) did not have significant differences in performance. However, higher current observed for TBS at poly-arginine/GCE is probably due to the higher surface coverage poly-arginine at GCE than BDD. It was concluded that for the systems under study, the poly-L-arginine/GCE was more suitable for TBS detection than that by the poly-L-arginine/BDD electrode, due to the more continuous and thicker poly-L-arginine film formed on the GCE, as revealed by the microscopy images. The TBS sensitivity and detection limit of the poly-L-arginine/GCE were determined to be 0.9 ±0.1 μA μmol-1L cm-2 and 0.10 μmol L-1, respectively, by chronoamperometry. Furthermore, the abilities of the electrodes to detect other β-agonists, namely clenbuterol and salbutamol, were studied by performing electrochemical experiments in the presence of these analytes. The results suggest that this film is a promising material for TBS detection due to high-surface-area electrochemical electrodes, and for the electrostatically-controlled thin film interference filter.