The electrochemical behaviour of cysteine (Cys) at a graphite electrode modified with gold nanoparticles (GAu nano electrode) was studied by cyclic voltammetry. It was found that the graphite electrode-Au nanoparticles show an electrocatalytic activity towards the oxidation of Cys in 0.1 M NaOH. At 0.05 V, there is an "inverse" maximum in the cathodic voltammogram of Cys. Using a G-Au nano electrode, the dependence of the peak current of the "inverse" maximum on Cys concentration was linear in the range from 1 to 14 pM, and the detection limit was 0.6 pM. The proposed analytical method is simple, rapid and sensitive.
The second for the significance livestock sector is pig breeding, which accounts for one-third of the country’s meat production. Long-term world practice of pig farming confirms the high maturity of this species of animals, excellent taste, nutritious meat and most importantly the ability to quickly increase food production, and thereby ensure the optimal balance of the diet of the population. One of the constraining factors for the development of this industry is the development of iron deficiency alimentary anemia in pigs during the first 7 days of animal life, which affects the growth, development and increase of live weight in animals. Without preventive measures to supplement the iron with animals, up to 100% of piglets become sick with anemia, which can lead to the death of a significant part of the young population. This article presents the results of the toxicological approbation of a new iron-containing preparation for farm animals. The question of finding a less toxic iron preparation with a higher prolonging effect is relevant.
A simple, rapid, and sensitive anodic stripping voltammetric method for the determination of Pt (IV) is described. It is based on depositing an intermetallic indium-platinum alloy phase on the surface of a modified graphite electrode, and recording the oxidation peak of indium from that alloy phase with the help of linear scan voltammetry. A systematic study of the behavior of different In-Pt phases revealed that the peak potential of indium oxidation from the different phases can be explained on the basis of simple thermodynamic considerations. Different alloy phases have characteristic peak potentials. For the purpose of analysis, it is possible to choose such conditions that only one specific alloy phase forms, viz. PtIn. This is the case for a concentration (milligrams per liter) ratio of In (III)/Pt(IV)050,000:1, at least.
The “inverse” cathodic peak of gold nanoparticles is observed in the reaction mixture used to obtain gold nanoparticles HAuCl4:Na3C6H5O7:NaBH4=125:8:1 and accumulation time is 90 s. The conditions in which methionine has the greatest electrochemical activity were determined. They are as follows: the molar ratio of reagents HAuCl4:Na3C6H5O7:NaBH4=125:8:1 and accumulation time is 90 s, 0.1 M NaOH. The mechanism of methionine oxidation is proposed to be on the surface of the graphite electrode modified with gold nanoparticles in 0.1 M NaOH. The determination limit of methionine is 0.7 •10-14 M. The proposed method is simple, sensitive, and does not need toxic substances.
It was established that the silver nanoparticles (AgNPs) in an equimolar ratio have the highest electrochemical activity on a graphite electrode (GE) surface in an alkaline medium. The electrocatalytic oxidation mechanism of hydrogen peroxide on the GE surface was proposed. We detected an additional maximum at E = 0.3 V on the cathodic branch of the cyclic curve in the potential range from +2.0 to -1.0 V. The appearance of this maximum indicates the reduction of hydrogen peroxide generated during AgNPs electrooxidation in the potential range from -1.0 to +2.0 V.
The stepwise mechanism of electrooxidation and reduction of silver nanophases and microphases is proposed on the graphite electrodes surface in alkaline medium. The electrochemical splitting of silver nanophases peak is observed on the anodic branch of the cyclic current-voltage curve. There is the shoulder at E = 0.2 V on the he anodic branch of cyclic current-voltage curve. The appearance of additional cathodic wave at E = -0.08 V is observed on the cathodic branch of the cyclic current-voltage curve that is caused by the reduction of silver nanoparticles. The additional cathode maximum is represented at 0.3 V on the cathodic branch of the cylic current-voltage curves of only silver nanophases. This effect is associated the catalytic process of decomposition of hydrogen peroxide on silver nanoparticles surface. The offset of the cathodic maxima of current-voltage curves of silver nanophases obtained with an excess of a reducing agent are observed to more negative potentials. There is a significant decrease of the all currents maxima compared to silver nanophases obtained with an equal molar ratio of reactants. These results may be connected with the formation of silver oxide monolayers in the different oxidation in the presence of large amounts a reducing agent. The excess of the reducing agent required for the preparation of silver nanoparticles leads to decrease of the cathodic maximum of silver nanoparticles
Influence of stabilizing agent and synthesis temperature on the optical properties of silver nanoparticles as active materials in surface plasmon resonance (SPR) email@example.com Abstract. The shape, size, optical properties and electrochemical activity of silver nanoparticles (AgNPs) obtained by chemical reduction methods depending on the preparation conditions were investigated. Silver sols consist of AgNPs of different shapes. They are as follows spherical -30 nm, polyhedral -35 nm, 50 nm nanorods. It was shown that the position of the absorption spectrum peak in AgNPs depend on the molar ratio of mixture AgNO 3 :Na 3 C 6 H 5 O 7 . The maximum of the absorption spectrum peak of AgNPs is shifted by 10 nm to longer wavelengths area in presence excess of a reducing agent or the increasing of boiling time. After storage for one week the spectrum intensity of AgNPs obtained in the mixture AgNO 3 :Na 3 C 6 H 5 O 7 = 1:1 is increased in comparison with freshly prepared AgNPs, which is caused by the increase of AgNPs quantity of a given size. The AgNPS obtained in the mixture AgNO 3 :Na 3 C 6 H 5 O 7 = 1:3 have the most electrochemical activity. The conditions that the AgNPs have the most electrochemical activity were found.
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