Time filter

Source Type

Bouabdallah S.,University of Carthage | Trabelsi H.,ACTAPharma | Dhia M.T.B.,Laboratoire Of Chimie Organique Structurale Synthese Et Etude Physico Chimique | Hamida N.B.,Laboratoire Of Chimie Analytique Et Electrochimie
Chromatographia | Year: 2012

The isomerization of perindopril has been investigated using dynamics chromatography and an unified equation introduced by Trapp that was based on stochastic and theoretical plate models to determine the energies. The isomerization rate constants and Gibbs activation energies of isomerization are directly calculated from chromatographic peak parameters, i.e., retention times of the inter-converting species, peak width at half height, and relative plateau height. From the rate constant $$ k 1 ue (T),$$, measured at variable temperatures, the kinetic eyring activation parameters ΔG #, ΔH # and ΔS # of isomerization of perindopril were obtained. By variation of the flow rate of the mobile phase, the expected independence of the isomerization barrier from the chromatographic time scale was demonstrated for the first time. The relationships between peak shape and chromatographic conditions, such as flow rate, temperature, pH, organic modifier, and β-cyclodextrin, such as an additive, were investigated. In addition, an NMR investigation on perindopril was described. © 2012 Springer-Verlag.

Mansour D.,National Graduate School of Chemistry, Rennes | Mansour D.,Laboratoire Of Chimie Analytique Et Electrochimie | Mansour D.,Institute National Des Science Appliquees Et Of Technology | Mansour D.,European University of Brittany | And 9 more authors.
Water, Air, and Soil Pollution | Year: 2012

The main objective of this study was to examine the effect of an electro-Fenton pretreatment on the biodegradability of sulfamethazine-polluted solutions. The aim of the pretreatment was only to degrade this molecule in order to increase the biodegradability of the effluent and therefore allow a subsequent biological treatment. Preliminary tests showed the absence of biodegradability of the target compound. The degradation of sulfamethazine by electro-Fenton process was then examined using a carbon felt cathode and a platinum anode in an electrochemical reactor containing 1 L of solution. The influence of some experimental parameters such as initial concentration, temperature and current intensity on the degradation by electro-Fenton step has been investigated. In addition, the biodegradability of the solution after electrochemical pretreatment was examined and showed a Biological Oxygen Demand (BOD 5) on Chemical Oxygen Demand (COD) ratio above the limit of biodegradability, namely 0.4, for several experimental conditions. The feasibility of coupling an electro-Fenton pretreatment with a biological degradation of by-products in order to mineralize polluted solutions of sulfamethazine was confirmed. © Springer Science+Business Media B.V. 2011.

Ouertani R.,Laboratoire Of Chimie Analytique Et Electrochimie | El Atrache L.L.,Laboratoire Of Chimie Analytique Et Electrochimie | Hamida N.B.,Laboratoire Of Chimie Analytique Et Electrochimie
International Journal of Chemical Kinetics | Year: 2013

The present paper deals with the hydrolysis of ethiofencarb [2-ethylthiomethyl(phenyl)-N-methylcarbamate] in alkaline solution. The reaction kinetics has been investigated using spectrophotometric and liquid chromatographic techniques. The rate constants were determined following a proposed first-order kinetic model. The positive activation entropy ΔS≠ = +100.07 J mol-1 K-1 and the absence of general basic catalysis indicated an E1cB hydrolytic mechanism, involving the formation of methyl isocyanate. This result was confirmed by the fact that ethiofencarb fits well into Brönsted and Hammett lines, obtained for a series of substituted N-methylcarbamate whose decomposition in aqueous media was established to follow an E1cB mechanism. © 2012 Wiley Periodicals, Inc.

Loading Laboratoire Of Chimie Analytique Et Electrochimie collaborators
Loading Laboratoire Of Chimie Analytique Et Electrochimie collaborators