Search results for "spray"
showing 10 items of 503 documents
High-performance liquid chromatographic, capillary electrophoretic and capillary electrophoretic–electrospray ionisation mass spectrometric analysis …
2002
Systems for efficient separation of selected alkaloid groups by high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrophoresis coupled with electrospray ionisation mass spectrometry (CE-ESI-MS) are described. The optimized HPLC system was applied for the separation of 23 standard indole alkaloids as well as for qualitative and quantitative analyses of crude alkaloid extracts of Rauvolfia serpentina X Rhazya stricta hybrid cell cultures. The developed conditions for CE analysis proved to be efficient for separation of mixtures of standard indole and beta-carboline alkaloids. The described buffer system is also applicable in the combination of CE w…
Ion mobility spectrometry evaluation of cocaine occupational exposure in forensic laboratories
2014
An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocaine in air of the breathing zone of operators, in laboratory surfaces and in nasal mucus of employees to evaluate cocaine exposure in a forensic laboratory. The analytical methodology has been validated in terms of accuracy, precision and limits of detection and results obtained were statistically comparable with those obtained by liquid chromatography. Cocaine concentration in laboratory air increases from 100 ± 35 ng m(-3) of a normal day to 10,000 ng m(-3) during the manipulation of cocaine seizures. The occupational exposure limit (OEL) for cocaine has not been established which difficult the…
Contribution to the study of spray formation
2012
The work of this thesis aims to provide and validate tools useful to study and understand the phenomena involved in the injection of fuel, mainly focused on intra-flow injector. These tools are numeric and simulate the formation of a spray. A first part focuses on zero-dimensional modelling. Models which predict these following characteristics of spray like the spray angle, the spray penetration or the liquid length are compared with experimental data. The conclusions are that zero-dimensional modelling provides good results very quickly in some cases. Although, a better understanding of the influence of cavitation on the spray, which requires an understanding of the intra-flow injector, co…
Cyclic Dinuclear Organotin Cations Stabilized by Bulky Substituents
2015
The syntheses of sterically congested 2,2-bis(diorganochloridostannyl)propane, Me2C(SnClR2)2 (1; R = CH(SiMe3)2), the related salts [cyclo-{Me2C(SnR2)2X}B(ArF)4] (2, X = Cl; 3, X = OAc; 4, X = OH; ArF = 3,5-(CF3)2C6H3), and the four-membered-ring cyclo-{Me2C(SnR2)2O} (5) are reported. The compounds have been characterized by elemental and EDX analyses, 1H, 11B, 13C, 19F, 29Si, and 119Sn NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis.
Toward multifunctional single-molecule magnets: characterization of dodecanuclear manganese complexes by electrospray ionization mass spectrometry.
2001
Single-molecule magnets (SMM) based on the dodecanuclear manganese complexes Mn12O12(RCOO)16 can be readily characterized by electrospray ionization mass spectrometry. This facilitates the synthesis of complex multifunctional molecules that have potential use in the organization of SMM into films or surfaces.
Sequestering ability of some chelating agents towards methylmercury(II).
2013
A study on the interactions between CH3Hg+ and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H2 TLA)), 3-mercaptopropanoic acid (H2 MPA), 2-mercaptosuccinic acid (thiomalic acid (H3 TMA)), d,l-penicillamine (H2 PSH), l-cysteine (H2 CYS), glutathione (H3 GSH), N,N′-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H6 MLT)) and ethylenediaminetetraacetic acid (H4 EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For t…
Fragmentations and reactions of the organophosphate insecticide Diazinon and its oxygen analog Diazoxon studied by electrospray ionization ion trap m…
2005
The fragmentations and reactions of Diazinon and related compounds have been studied by electrospray ionization ion trap mass spectrometry. Several novel fragmentation and rearrangements have been observed, including an intramolecular thiono-thiolo rearrangement. The stability, in the gas-phase, of the protomers of 2-isopropyl-4-methyl-6-pyrimidinol has been demonstrated. The complexity of the gas phase ion processes observed suggest that, at present, caution Should be exercised in using this approach for the analysis of environmental and other samples until our understanding of these processes increases considerably. (J Am Soc Mass Spectrom 2005, 16, 515-523) (c) 2005 American Society for …
Confirmation of Fenthion Metabolites in Oranges by IT-MS and QqTOF-MS
2007
14 pages, 4 figures, 4 tables.-- PMID: 18020315 [PubMed].-- Printed version published Dec 15, 2007.
Gas-phase ion chemistry of protonated melatonin
2009
The gas-phase ion chemistry of protonated melatonin has been investigated by mass spectrometric (MS) techniques involving chemical ionisation, fast atom bombardment and electrospray ionisation. Either naturally-occurring or collision-induced decomposition experiments have been carried out using side chain tetra-deuterium-labelled derivatives, as well as the corresponding N–D derivatives obtained by exchange with D2O. The analysis of experimental results allows definite pathways for the formation of the ion at m/z 174 to be assigned and sheds some more light on the overall fragmentation pathways. Experiments on labelled derivatives evidenced H–D scrambling processes during fragmentation.
Degrees of freedom effect on fragmentation in tandem mass spectrometry of singly charged supramolecular aggregates of sodium sulfonates
2012
The characteristic collision energy (CCE) to obtain 50% fragmentation of positively and negatively single charged noncovalent clusters has been measured. CCE was found to increase linearly with the degrees of freedom (DoF) of the precursor ion, analogously to that observed for synthetic polymers. This suggests that fragmentation behavior (e.g. energy randomization) in covalent molecules and clusters are similar. Analysis of the slope of CCE with molecular size (DoF) indicates that activation energy of fragmentation of these clusters (loss of a monomer unit) is similar to that of the lowest energy fragmentation of protonated leucine-enkephalin. Positively and negatively charged aggregates be…