Showing papers on "Polarography published in 2021"
TL;DR: In this paper, it was shown that the second-order reaction of atropine to N-oxide was a second order reaction and that the best oxidant was potassium peroxymonosulfate, since 100% yield was achieved within 15min.
Abstract: The work presents the obtaining of atropine N-oxide using various peroxyacids (organic monoperoxyacid, diperoxyacids and inorganic peroxyacids). The kinetics of atropine oxidation with various oxidants, for example Oxone, m-chloroperoxybenzoic acid, diperoxysebasic acid and diperoxyazelaic acid, was studied. The optimal conditions for obtaining of atropine N-oxide (oxidation duration, pH) are given in the work. It was established that the best oxidant was potassium peroxymonosulfate, since 100% yield of atropine N-oxide was achieved within 15 min. In this work, we showed that the oxidation reaction of atropine to N-oxide was a second-order reaction. The rate constants of these reactions were established. The electrochemical behavior of atropine N-oxide obtained using potassium peroxymonosulfate and m-chloroperoxybenzoic acid on a mercury dropping electrode was investigated. Atropine N-oxide was reduced forming two peaks. Each reduction peak involved 1 electron and 1 proton.
2 citations
DOI•
30 Jun 2021
TL;DR: In this article, the surface properties of graphite, MWCNTs and rGO composite electrodes were modified by using nanoparticles to improve electroanalytical sensor response, which can lower detection limits and widen the linear range.
Abstract: Many carbon materials are well-known conductive materials, widely used in the fabrication of composite electrodes. In this work, diverse allotropic forms of carbon such as graphite, MWCNTs and rGO were tested. Furthermore, these materials allow the construction of cheaper, smaller, portable, reliable and easy-to-use devices, which can be easily modified. The above-mentioned composite electrodes were developed for metal analysis in water such as Cu, Cd and Pb that, at a high concentration, can have consequences on human health. SWASV is the selected technique. It would be ideal to exploit the potential properties of mercury for metal detection by tuning the electrode’s surface. Due to mercury’s hazardous properties and to reduce the amount of this substance used in polarography, the use of nanoparticles is a good option due to their properties. Mercury nanoparticles were used to modify the surface of the composite electrodes to improve electroanalytical sensor response. For this reason, using these modified composite electrodes can lower detection limits and widen the linear range that can be achieved for Cd (0.05–1 mg·L−1) and Pb (0.045–1 mg·L−1). However, for Cu (0.114–1.14 mg·L−1), meaningful variations were not observed compared to the bare electrode.
TL;DR: In this article, the 1-nitro-6-sulfonic acid was shown to polarographically reduce in a strong acidic medium in the presence of 0.1 N H2SO4 to the corresponding naphthalene aminos sulfonic acid in a single sixelectron stage via an intermediate formation of hydroxylamine.
Abstract: Electrochemical behavior of naphthalene 1-nitro-6-sulfonic acid was studied by polarography, voltammetry on glassy carbon electrodes, and electrolysis at controlled potential and in galvanostatic mode. The 1-nitro-6-sulfonic acid, like α-nitronaphthalene and naphthalene 1-nitro-3,6,8-trisulphonic acid, was shown to be polarographically reduced in a strong acidic medium in the presence of 0.1 N H2SO4 to the corresponding naphthalene aminosulfonic acid in a single six-electron stage via an intermediate formation of hydroxylamine. Deceleration of the 1-nitro-6-sulfonic acid polarographic reduction manifesting itself as a decrease of the polarographic current, as well as strong dependence of the polarization curves’ parameters and shape on the neutral and alkaline supporting solution composition and pH, are related to anionic character of the species being reduced, which is caused by the presence of acidic sulfonic group in their molecules. The technological parameters for the naphthalene 1-amino-6-sulfonic acid preparative electrosynthesis are determined: the current density 5–10 A/dm2, temperature 30–32°C, and concentration of the initial nitro-compound 10–13%, which provide the target product yield of 87.0–93.5%, the current efficiency of 38.0–42.4%, and recovery of 69.0–80.0% (on the N3 grade nickel and Kh18N10Т-stainless-steel cathodes in ammonia buffer solutions with pH 7.0–8.2). To increase the electroreduction efficiency of the nitro-Cleve’s acids’ technical isomeric mixture reduction, the mixture preliminary purification and the using of inert atmosphere are recommended in the processes of both electrolysis and the target Cleve’s-acid extraction from the solution.