Search results for "Amide"
showing 10 items of 3119 documents
Direct flow injection chemiluminescence determination of salicylamide
1999
Abstract A new direct flow injection chemiluminescence method is proposed for the determination of salicylamide, based upon the oxidation of the drug by potassium permanganate in dilute sulphuric acid. The calibration graph is linear over the range 20 ng ml−1 (30 limit of detection)–8 μg ml−1 salicylamide, with a relative standard deviation (n=50, 0.5 μg ml−1) of 1.7%. The average sample insertion rate is 142 h−1. The influence of relevant foreign compounds is found to be relatively slight. The method is applied to the determination of salicylamide in a pharmaceutical formulation and human urine.
Evaluation of P-glycoprotein (abcb1a/b) modulation of [18F]fallypride in MicroPET imaging studies
2012
[(18)F]Fallypride ([(18)F]FP) is an important and routinely used D2/D3 antagonist for quantitative imaging of dopaminergic neurotransmission in vivo. Recently it was shown that the brain uptake of the structurally related [(11)C]raclopride is modulated by P-glycoprotein (P-gp), an important efflux transporter at the blood-brain barrier. The purpose of this study was to determine whether the brain uptake of [(18)F]FP is influenced by P-gp. For examination of this possible modulation microPET studies were performed in a rat and a mouse model. Hence, [(18)F]FP was applied to Sprague Dawley rats, half of them being treated with the P-gp inhibitor cyclosporine A (CsA). In a second experimental s…
Impact of high-pressure processing on vitamin E (α-, γ-, and δ-tocopherol), vitamin D (cholecalciferol and ergocalciferol), and fatty acid profiles i…
2012
In the present study, four high-pressure (HP) treatments (100, 200, 300, and 400 MPa) of 9 min duration were evaluated to assess their effect on the lipid fraction (fat-soluble vitamins and fatty acid profile) of an orange juice-milk and a vegetable beverage. After HP treatment, nonsignificant changes in vitamin D(2) and D(3) contents were observed for both beverages. An increase in vitamin E activity was observed in HP beverages when pressures >100 MPa were applied, mainly due to an increase in α-tocopherol content. Only a small reduction in fat content was found for the orange juice-milk beverage, but no changes were observed for the vegetable beverage. A significant decrease in SFA level…
Microbial inactivation and evaluation of furan formation in high hydrostatic pressure (HHP) treated vegetable-based infant food.
2017
Abstract The inactivation of pathogenic and spoilage bacteria as well as the formation of food processing contaminants (e.g. acrylamide, furan, etc.) in infant foods is of utmost importance for industry, consumers as well as regulatory bodies. In this study, the potential of high hydrostatic pressure (HHP) for microorganism inactivation including total mesophilic aerobic bacteria (TMA) and total yeasts and molds (TYM) at equivalent processing conditions, as well as its effects on furan formation in vegetable-based infant food was evaluated. The process parameters evaluated were combinations of pressures (200, 300, and 400 MPa), temperatures (25, 35, and 45 °C), and treatment times (5, 10, a…
Estimation of formamide harmonic and anharmonic modes in the Kohn-Sham limit using the polarization consistent basis sets.
2010
Formamide harmonic and anharmonic frequencies of fundamental vibrations in the gas phase and in several solvents were successfully estimated in the B3LYP Kohn-Sham complete basis set limit (KS CBS). CBS results were obtained by extrapolating a power function (two-parameter formula) to the results calculated with polarization-consistent basis sets. Anharmonic corrections using the second order perturbation treatment (PT2) and hybrid B3LYP functional combined with polarization consistent pc-n (n = 0, 1, 2, 3, 4) and several Pople’s basis sets were analyzed for all fundamental formamide vibrational modes in the gas phase and solution. Solvent effects were modeled within a PCM method. The anhar…
Synthesis, characterization and thermal properties of new aromatic quaternary ammonium bromides
2004
Series of new aromatic R 2R′ 2N +Br - (R=benzyl, 4-methylbenzyl, 2-phenylethyl, 3-phenylpropyl; R′=ethyl, methyl, isopropyl) or RR′ 2NH +Br --type (R=benzyl, R′=isopropyl) quaternary ammonium bromides were prepared by using novel synthetic route in which a formamide (N,N-diethylformamide, N,N-dimethylformamide, N,N-diisopropylformamide) is treated with aralkyl halide in presence of a weak base. The compounds were characterized by 1H-NMR and 13C-NMR spectroscopy and mass spectrometry. Structures of the crystalline compounds were determined by X-ray single crystal diffraction, and in addition the powder diffraction method was used to study the structural similarities between the single crysta…
Halogen and Hydrogen Bonded Complexes of 5-Iodouracil
2013
Three derivatives of 5-iodouracil were prepared, and their complexation properties, supplemented by 5-iodouracil under the same conditions, were studied with and without halogen bond acceptors in N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide, formamide, dimethylsulfoxide, and water. The intermolecular halogen and hydrogen bonding interactions observed in the solid state were investigated using single crystal X-ray diffraction and quantum chemical calculations, and the acquired data were contrasted with bonding interactions previously reported for 5-iodouracil in the Cambridge Structural Database. It was found that the polarized iodine atom and the amidic NH functionality ac…
Study of AOT-stabilized microemulsions of formamide and n-methylformamide dispersed in n-heptane
1997
Abstract A wide investigation of some physicochemical properties (density, viscosity, conductance, IR spectra, permittivity) of AOT-stabilized dispersions of formamide and n -methylformamide in n -heptane has been performed. The experimental data are consistent with the hypothesis that these highly hydrophilic substances are encapsulated within AOT reversed micelles and that this structure is maintained for both systems well above the volume fraction of the dispersed phase where a percolative transition occurs. In addition, the observed properties of these microemulsions reveal the pivotal role of intermicellar attractive interactions in driving the percolative transition. A marked modifica…
The mechanism of formamide hydrolysis in water from ab initio calculations and simulations.
2005
The neutral hydrolysis of formamide in water is a suitable reference to quantify the efficiency of proteolytic enzymes. However, experimental data for this reaction has only very recently been obtained and the kinetic constant determined experimentally is significantly higher than that predicted by previous theoretical estimations. In this work, we have investigated in detail the possible mechanisms of this reaction. Several solvent models have been considered that represent a considerable improvement on those used in previous studies. Density functional and ab initio calculations have been carried out on a system which explicitly includes the first solvation shell of the formamide molecule…
Chromatographically separable rotamers of an unhindered amide
2014
Surprisingly stable formamide rotamers were encountered in the tetrahydroisoquinoline and morphinan series of alkaloids. We investigated the hindered rotation around the amide bond by dynamic high-performance liquid chromatography (DHPLC) and kinetic measurements of the interconversion of the rotamers which can readily be separated by HPLC as well as TLC. The experimental results of the different methods were compared to each other as well as to results obtained by DFT calculations.