Search results for "Formate"
showing 10 items of 111 documents
Determination of sertraline in rat plasma by HPLC and fluorescence detection and its application toin vivopharmacokinetic studies
2012
A simple, rapid, and sensitive HPLC method based on 9H-fluoren-9-ylmethyl chloroformate derivatization for the quantification of sertraline in rat plasma has been developed, requiring a plasma sample of only 0.1 mL, which was deproteinized and derivatized for 5 min in two single steps. The obtained derivative was stable at room temperature and was determined by HPLC using a fluorescence detector. The analytical column was a C(18) column and the mobile phase was acetonitrile and water (80:20, v/v). Calibration curves were linear in the range of 10-500 ng/mL. The limit of detection was approximately 3 ng/mL, and the lower limit of quantification was established at 10 ng/mL. The bias of the me…
Mechanismus der Umsetzung von 1,1-Diphenylhydrazin mit Azodicarbonsäure-diethylester
1979
Bei der Umsetzung von 1,1-Diphenylhydrazin (1a) mit Azodicarbonsaure-diethylester (2a) uber-lagern sich funf Reaktionsmechanismen: A und B) Oxidation des Diphenylhydrazins 1a durch den Azodicarbonsaureester 2a zum Aminonitren 8; Bildung des Tetrazens 10 entweder durch Dimerisierung von 8 oder uber das Tetrazan 11; Zerfall von 11 in N2 und Diphenylamin. — C) Addition des Aminonitrens 8 an den Azodicarbonsaureester 2a zum Aminoazimin 3a; Zerfall von 3a in das Urethan 4a und den Azidoameisensaureester 5a. — D) Isomerisierung des Aminoazimins 3a zu 13 und Reduktion von 13 durch 1a zum Tetrazen 14; Spaltung von 14 in Diphenylamin und das Azid 15; Zerfall von 15 in Ethylcyanat (17) und den Kohlen…
Derivatization of amines in solid-phase extraction supports with 9-fluorenylmethyl chloroformate for liquid chromatography
1997
Abstract A new method based on reaction in solid-phase extraction cartridges with 9-fluorenylmethyl chloroformate is described for improved derivatization of amines prior to liquid chromatography. The effects of the reaction conditions, the kinetics of the reaction and the kind of packing material on the derivatization have been evaluated. The reliability of the described approach has been tested by derivatizing propylamine, diethylamine, diethanolamine, glycine, glutamic acid, p-aminobenzoic acid and β-phenylethylamine. Reaction yields compared with those of the analogous solution derivatizations were in the 44–169% range, and satisfactory linearity was achieved at concentrations of the am…
Le pilotage par l'Etat de la formation des enseignants du début des années 1990 à nos jours.
2012
Guy Lapostolle, Rachel Solomon et Pascal Grisoni proposent d'étudier les transformations historiques de la notion de " professionnalisation ", vue à travers la lentille de l'État, des années 1990 à nos jours. Leur étude a pour objet de présenter et d'analyser, à partir de textes officiels en provenance de l'État et d'un certain nombre de rapports d'experts concernant la formation et le recrutement des enseignants, ce que l'État attend des enseignants qu'il souhaite voir travailler à son service. En prenant appui sur les usages faits de la notion, sur les finalités plus ou moins explicites qui lui sont conférées et sur les contenus de formation et les modalités de recrutement proposés, les a…
Enseignement technique et professionnel au Cameroun
2012
Le Cameroun, en tirant les leçons de la crise des années 90, a développé l'enseignement technique et la formation professionnelle ETFP. Comment est organisé ce sous-secteur ? Quelle articulation avec l'enseignement général et le marché de l'emploi ? Après une présentation globale du système éducatif, cet ouvrage décrit le sous-secteur de l'ETFP au Cameroun et la manière dont est organisée la formation des formateurs.
Comparison of organic peracids in wastewater treatment: Disinfection, oxidation and corrosion.
2015
The use of organic peracids in wastewater treatment is attracting increasing interest. The common beneficial features of peracids are effective anti-microbial properties, lack of harmful disinfection by-products and high oxidation power. In this study performic (PFA), peracetic (PAA) and perpropionic acids (PPA) were synthesized and compared in laboratory batch experiments for the inactivation of Escherichia coli and enterococci in tertiary wastewater, oxidation of bisphenol-A and for corrosive properties. Disinfection tests revealed PFA to be a more potent disinfectant than PAA or PPA. 1.5 mg L(-1) dose and 2 min of contact time already resulted in 3.0 log E. coli and 1.2 log enterococci r…
An evaluation of solid phase microextraction for aliphatic amines using derivatization with 9-fluorenylmethyl chloroformate and liquid chromatography
2005
The reliability of SPME combined with a chemical reaction for the analysis of short-chain aliphatic amines by liquid chromatography has been investigated. Different options to couple SPME and derivatization have been tested and compared: (i) derivatization of the analytes in solution followed by the extraction of the derivatives, (ii) extraction of the analytes and subsequent derivatization by immersing the SPME fibre onto a solution of the reagent, and (iii) extraction/derivatization of the analytes using fibres previously coated with the reagent. Methylamine (MA), dimethylamine (DMA) and trimethylamine (TMA) have been selected as a model of primary, secondary and tertiary amines, respecti…
Analysis of 18 perfluorinated compounds in river waters: Comparison of high performance liquid chromatography–tandem mass spectrometry, ultra-high-pe…
2012
In this work, the performance of ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and capillary liquid chromatography-mass spectrometry (CLC-MS) has been studied for the analysis of eighteen perfluorinated compounds in water samples. UHPLC-MS/MS and CLC-MS analysis were carried out using a Zorbax C-18 column (50 mm × 2.1 mm, 1.8 μm) and a Zorbax SB-C18 column (150 mm × 0.5 mm, 3.5 μm), respectively, in gradient elution mode with a mobile phase of ammonium formate and methanol. Both techniques were compared with conventional LC-MS/MS in terms of speed, sensitivity, selectivity and resolution. Water samples were extracted by solid phase extraction (SPE). Mea…
Iodide-Photocatalyzed Reduction of Carbon Dioxide to Formic Acid with Thiols and Hydrogen Sulfide.
2016
The photolysis of iodide anions promotes the reaction of carbon dioxide with hydrogen sulfide or thiols to quantitatively yield formic acid and sulfur or disulfides. The reaction proceeds in acetonitrile and aqueous solutions, at atmospheric pressure and room temperature by irradiation using a low-pressure mercury lamp. This transition-metal-free photocatalytic process for CO2 capture coupled with H2 S removal may have been relevant as a prebiotic carbon dioxide fixation.
Effect of commercial mineral-based additives on composting and compost quality.
2009
Abstract The effectiveness of two commercial additives meant to improve the composting process was studied in a laboratory-scale experiment. Improver A (sulphates and oxides of iron, magnesium, manganese, and zinc mixed with clay) and B (mixture of calcium hydroxide, peroxide, and oxide) were added to source-separated biowaste:peat mixture (1:1, v/v) in proportions recommended by the producers. The composting process ( T , emissions of CO 2 , NH 3 , and CH 4 ) and the quality of the compost (pH, conductivity, C/N ratio, water-soluble NH 4 –N and NO 3 –N, water- and NaOH-soluble low-weight carboxylic acids, nutrients, heavy metals and phytotoxicity to Lepidium sarivum ) were monitored during…