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.
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