Zein film as a novel natural biopolymer membrane in electrochemical detections

Permselective modifier films are very important in preparing highly sensitive electrochemical sensors. In this work, for the first time, the behavior of gold and glassy carbon electrodes coated with biocompatible zein film as a permselective membrane for the electrochemical detection of various compounds has been investigated. For this purpose, several electroactive cationic (methylene blue, brilliant green, and thionine) and anionic (potassium ferricyanide, alizarin red S, and riboflavin-5’-phosphate) compounds have been used as model. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that zein membranes prepared from casting solution containing 1% zein in ethanol/water have porous structures with high nanometric roughness. The capacitance values of electrical double layers of electrodes modified with zein film were very high for hydrophilic ions in comparison with hydrophobic ions. Point of zero charge pH (pH_pzc) of zein membrane was 4.8. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) as well as pH_pzc study indicated that zein permselective membrane acts as ion exchanger film for selected cationic compounds with fast electrochemical kinetics responses in aqueous solution (pH=7). This behavior was confirmed by circulating solutions containing model compounds from homemade continuous cell equipped with polyamide membranes modified with zein film.

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N-Protection of amines using pyridinium 2, 2, 2-trifluoroacetate ionic liquid as an efficient and reusable catalyst

A simple, green, and efficient method for the N-tert-butoxycarbonylation of amines by pyridinium 2,2,2- trifluoroacetate （[Py][OTf]） as an efficient and reusable catalyst is reported. In general, electron donating groups on aryl group give rise to the higher yields than electron withdrawing groups. Clean reaction, short reaction times, high yields, reusability of catalyst, and easy preparation of it are some advantages of this work.     

Voltammetric Determination of Bisphenol A in Water and Juice Using a Lanthanum (III)-Doped Cobalt (II,III) Nanocube Modified Carbon Screen-Printed Electrode

A La³⁺ doped Co₃O₄ nanocube modified graphite screen-printed electrode (La³⁺-doped Co₃O₄ nanocube/SPE) was prepared and utilized for the sensitive voltammetric determination of bisphenol A. In comparison with an unmodified electrode, the presence of the La³⁺ doped Co₃O₄ nanocubes caused a significant enhancement in the peak current. Differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometry approaches were utilized as diagnostic methods. The modified SPE was used to determine bisphenol A concentrations in the range from 0.5 to 900.0?μM with a limit of detection equal to 6.1?×?10^?8 M. Real samples were effectively analyzed with the modified electrode.     

Electrochemical Determination of Sertraline at Screen Printed Electrode Modified with Feather Like La3+/ZnO Nano-Flowers and Its Determination in Pharmaceutical and Biological Samples

Russian Journal of Electrochemistry - In this paper, the use of a screen printed electrode modified by feather like La3+/ZnO nano-flowers for the determination of sertraline was described. These...     

Voltammetric determination of hydroxylamine in water samples using a 1-benzyl-4-ferrocenyl-1H-[1,2,3]-triazole/carbon nanotube-modified glassy carbon electrode

A modified glassy carbon electrode has been constructed using a 1-benzyl-4-ferrocenyl-1H-[1,2,3]-triazole along with multiwalled carbon nanotubes. The electrochemical behaviour of modified electrode has been investigated by cyclic voltammetry. Electrocatalytic activity of the modified electrode was investigated for the oxidation of hydroxylamine in 0.1 M phosphate-buffered solution of pH 8. The modified electrode showed electrocatalytic response to the oxidation of hydroxylamine at the potential of 330 mV. The linear range and detection limit for the detection of hydroxylamine in the optimum condition were found to be 4.0?×?10^?7 to 6.75?×?10^?4 M and 28.0?±?1.0 nM, respectively. Finally, the method was employed for the determination of hydroxylamine in water samples.     

Suzuki–Miyaura coupling catalyzed by palladium nanoparticles biosynthesized using Glycyrrhiza glabra as reducing and stabilyzing agent

An unprecedented environmentally friendly method has been developed for the synthesis of palladium nanoparticles supported on Glycyrrhiza glabra. The synthesized nanoparticles were utilized in Suzuki–Miyaura reaction between different aryl halides and aryl bronic acid in aqueous media. This heterogeneous catalyst can be reused and recycled repeatedly more than five times with only slight loss of its initial catalytic efficiency. This reaction carrid out under atmospheric pressure with high efficiency, unique and simple work‐up procedure and excellent yields.     

Application of a 1‐benzyl‐4‐ferrocenyl‐1H‐[1,2,3]‐triazole/carbon nanotube modified glassy carbon electrode for voltammetric determination of hydrazine in water samples

The electrochemical behaviour of hydrazine at a 1‐benzyl‐4‐ferrocenyl‐1H‐[1,2,3]‐triazole‐triazole/carbon nanotube modified glassy carbon electrode has been studied. The modified electrode shows an excellent electrocatalytic activity for the oxidation of hydrazine and accelerates electron transfer rate. The electrocatalytic current increases linearly with hydrazine concentration in the range 0.5–700.0 μm and the detection limit for hydrazine was 33.0 ± 2.0 nm . The diffusion coefficient (D = 2.5 ± 0.1 × 10^?5 cm² s^?1) and kinetic parameters such as the electron transfer coefficient, (α = 0.52) and the heterogeneous rate constant (k′ = 5.5 ± 0.1 × 10^?3 cm s^?1) for hydrazine were determined using electrochemical approaches. Finally, the method was employed for the determination of hydrazine in water samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Bromination of Some Aromatic Compounds with Potassium Bromide in the Presence of Benzyltriphenylphosphonium Peroxodisulfate

A simple, efficient, and mild method for selective bromination of some activated aromatic compounds using potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate in nonaqueous solution is reported. The results obtained revealed good to excellent selectivity between ortho and para positions of phenols and methoxyarenes.     

Analytical Nusselt number for forced convection inside a porous-filled tube with temperature-dependent thermal conductivity arising from high-temperature applications

Journal of Thermal Analysis and Calorimetry - The convection heat transfer inside a tube filled with a porous material under the constant heat flux thermal boundary condition which is widely used...