Search results for "Voltammetry"
showing 10 items of 404 documents
Dating archaeological strata in the Magna Mater temple using solid-state voltammetric analysis of leaded bronze coins
2017
[EN] The application of solid state electrochemistry techniques for dating archaeological strata using lead-containing bronze coins is described. The proposed methodology was applied to samples coming from the Roman archaeological site of Magna Mater Temple (Rome, Italy) occurring in different strata dating back between the second half and the end of the 4(th) century A.D. and the 20(th) century. The voltammetric signatures of copper and lead corrosion products in contact with aqueous acetate buffer, as well as the catalytic effects produced on the hydrogen evolution reaction, were used for establishing the age of different strata and dating coins belonging to unknown age. Voltammetric data…
Evaluation of Flavonoid Derivative and Doxorubicin Effects in Lung Cancer Cells (A549) Using Differential Pulse Voltammetry Method.
2018
Purpose: Electrochemical measurements have prompted the progress as a consequence of their affectability, cost-affectivity and comparatively short examination time. The aim of this study was the fast evaluation of the effect of chemotherapy compounds on the viability of lung cancer cells (A549) via electrochemical methods. Methods: Cyclic voltammetry (CV) was used as a primary method to distinguish between electrochemical behavior of normal and lung cancer cells. Differential pulse voltammetry (DPV) was employed as a complementary analyses method for the impact of doxorubicin (DOX) and Flavonoid modified drug (FMD) (US patent Application number: 62548886) on Lung cancer cells. Results: Only…
EFFECT OF IONIC STRENGTH AND MEDIUM COMPOSITION ON THE REMOVAL OF Pb2+ BY ALGINATE GEL BEADS. DPVASV AND ICP-OES MEASUREMENTS.
2012
The biosorption, i.e. a passive sequestering process by metabolically inactive biomass, shows a growing interest for toxic metal ions removal from contaminated aqueous solutions (1), such as municipal and industrial wastewaters. Since the sorption mechanism occurs mainly by ion exchange between the metal ion present in solution and the counter ion of the biopolymer (2), the efficiency of the sorption process largely depends on ionic strength and on the medium composition of solution containing the metal ion to be removed. In order to evaluate quantitatively the influence of ionic strength and medium on the metal removal process by the biomass, we report here results of a study on the sorpti…
STABILITY AND ORGANOCATALYTIC EFFICIENCY OF N-HETEROCYCLIC CARBENES ELECTROGENERATED IN ORGANIC SOLVENTS FROM IMIDAZOLIUM IONIC LIQUIDS
2015
The kinetic of degradation of 1-butyl-3-methylimidazole-2-ylidene (selected as model N-heterocyclic carbene - NHC), generated in organic solvents by cathodic reduction of the parent 1-butyl-3- methylimidazolium salts BMIm-X, was studied by a simple voltammetric analysis. The effect of NHC degradation rate on the efficiency of an organocatalyzed reaction (the synthesis of g-butyrolactone from cinnamaldehyde and trifluoromethylacetophenone) was investigated. The nature of the solvent and of the anion X have a remarkable effect on the stability of the NHC, the bis(trifluoromethylsulfonyl) imide anion being the best for a long lasting carbene (while acetonitrile seems to be the worst solvent). …
De l’ingénierie de protéines de liaison aux odorants à la détection électrochimique de molécules volatiles vers la conception de biocapteurs et nez é…
2014
The detection of odorant molecules has become an important challenge in different research area, such as the food industry, medical diagnostics and homeland security. Indeed, the thousands of odorants in our environment provide information on their chemical nature or their concentration. Human olfactory system is capable of discriminating thousands of different molecules thanks to biochemical mechanisms involving multiple protein receptor partners and a combinatorial coding. These biomolecules that include olfactory receptors and odorant-binding proteins (OBP) represent an interesting source of detectors for the design of biosensors. OBPs are small soluble proteins present in nasal mucus at…
Application of polydopamine functionalized zinc oxide for glucose biosensor design
2021
Zinc oxide (ZnO) nanostructures are widely used in optical sensors and biosensors. Functionalization of these nanostructures with polymers enables optical properties of ZnO to be tailored. Polydopamine (PDA) is a highly biocompatible polymer, which can be used as a versatile coating suitable for application in sensor and biosensor design. In this research, we have grown ZnO-based nanorods on the surface of ITO-modified glass-plated optically transparent electrodes (glass/ITO). Then the deposition of the PDA polymer layer on the surface of ZnO nanorods was performed from an aqueous PDA solution in such a way glass/ITO/ZnO-PDA structure was formed. The ZnO-PDA composite was characterized by S…
Polysubstituted ferrocenes as tunable redox mediators
2018
A series of four ferrocenyl ester compounds, 1-methoxycarbonyl- (1), 1,1’-bis(methoxycarbonyl)- (2), 1,1’,3-tris(methoxycarbonyl)- (3) and 1,1’,3,3’-tetrakis(methoxycarbonyl)ferrocene (4), has been studied with respect to their potential use as redox mediators. The impact of the number and position of ester groups present in 1–4 on the electrochemical potential E1/2 is correlated with the sum of Hammett constants. The 1/1+–4/4+ redox couples are chemically stable under the conditions of electrolysis as demonstrated by IR and UV–vis spectroelectrochemical methods. The energies of the C=O stretching vibrations of the ester moieties and the energies of the UV–vis absorptions of 1–4 and 1+–4+ c…
Design and Characterization of Effective Ag, Pt and AgPt Nanoparticles to H2O2 Electrosensing from Scrapped Printed Electrodes
2019
The use of disposable screen-printed electrodes (SPEs) has extraordinarily grown in the last years. In this paper, conductive inks from scrapped SPEs were removed by acid leaching, providing high value feedstocks suitable for the electrochemical deposition of Ag, Pt and Ag core-Pt shell-like bimetallic (AgPt) nanoparticles, onto screen-printed carbon electrodes (ML@SPCEs, M = Ag, Pt or AgPt, L = metal nanoparticles from leaching solutions). ML@SPCEs were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results were compared to those obtained when metal nanoparticles were synthesised using standard solutions of metal salts (MS@…
Dating archaeological copper/bronze artifacts by using the voltammetry of microparticles.
2014
A method for dating copper/bronze archaeological objects aged in atmospheric environments is proposed based on the specific signals for cuprite and tenorite corrosion products measured through the voltammtry of microparticles method. The tenorite/cuprite ratio increased with the corrosion time and fitted to a potential law that yielded a calibration curve usable for dating purposes.
Formaldehyde and total aldehydes in indoor air of public environments by voltammetry
2014
The proposed method involves active sampling, where a sampling pump is used to pull air through a solution and voltammetric analysis of the obtained solutions. No interferences have been observed. In addition, very little sample preparation is required. Analyses were performed in 19 indoor stations and one in outdoor. Measurements were carried out on University environments: Museum of Chemistry, Zoological Museum, libraries, laboratories, corridors, meeting rooms, photocopying room, machine shop and terrace. Formaldehyde concentrations in analyzed samples ranged from 2.6 to 85 μg m-3 (median = 32 μg m-3), while the sum of others aldehydes ranged from 2 to 25 μg m-3 (median =2.4 μg m-3). In …