Search results for "SPECTROSCOPY"
showing 10 items of 10293 documents
Mößbauer- und ESCA-Untersuchungen zur Bildung oxidischer Eisenphasen in wäßrigen Medien unter der Einwirkung organischer Korrosionsinhibitoren
1982
Korrosionsschichten auf Stahl nach Exposition in Wasser mit bestimmter Harte und Chloridgehalt wurden hinsichtlich der Wirksamkeit beigefugter organischer Inhibitoren mittels Mosbauer- und ESCA-Spektroskopie untersucht. Es entstehen relativ dicke Schichten mit einem unerwartet niedrigen Eisengehalt in Form von FeOOH. Die Schichten enthalten merkliche Mengen von Ionen aus der Testlosung und auch Abbauprodukte der Inhibitormolekule. Letztere werden anscheinend in dem korrosiven Medium zersetzt. Es ist anzunehmen, das das Gesamtmolekul zwar den Transport des Inhibitors zum Metall beeinflust, die eigentliche Inhibierung aber allein durch funktionelle Gruppen erfolgt. Mossbauer and ESCA investig…
Application of the small-angle neutron scattering technique to the study of solubilization mechanisms of organic molecules by micellar systems
1996
Abstract We present the possible contribution of the small-angle neutron scattering (SANS) technique to the molecular interpretation of the solubilization phenomena in simple micellar systems. We show for a few ternary micellar systems, that an appropriate analysis of SANS experimental data can provide information on modifications induced on micellar dimension, shape, number of monomer, and charge and on the partition coefficient of the additive and its localization inside the micellar aggregate. The influence of n -alcohols on the thermodynamics and on the structure of sodium dodecyl sulphate (SDS) aqueous solution has been extensively investigated, so the agreement between the results obt…
INTERACTIONS OF ORGANOTIN(IV) HALIDES WITH REDUCED GLUTATHIONE IN AQUEOUS-SOLUTION
1993
Abstract Glutathione (GSH) is a compound extremely common among many living organisms in which it plays a fundamental role in the processes of detoxification. Also, organotin(IV) derivatives are more and more commonly used in technological processes or as antitumor drugs. So it seemed interesting to investigate the possible interactions between GSH and organotin compounds in water. Particularly, it has been studied because of its role in the organic radicals linked to the tin center on the stoichiometry and the structure of the adducts. Information was obtained following the reaction between Me n SnCl 4-n (n = 1 to 3) and GSH by Mossbauer and NMR spectroscopies on the assumption that change…
The interaction of organotins with native DNA
1992
The compounds R2SnCl2 and R3SnCl (RMe, Et, nBu, nOct, Ph, in ethanol solution) as well as the aqueous species [Me2Sn(OH2)n]2+ and [Me3Sn(OH2)2]+, react with aqueous native DNA, yielding solid phases. According to the pointcharge model treatment of the 119Sn Mossbauer parameter nuclear quadrupole splitting, trans-octahedral R2Sn(O2PXY)2, and trigonalbipyramidal R3Sn(O2PXY), (RMe, Et, nBu), would occur in the pellets, the tin atoms being coordinated by phosphodiester groups of the nucleic acid. The precipitates from Ph2SnIV would consist of the DNA complex as well as of the Ph2SnIV distannoxane obtained by hydrolysis of the reactant, whilst nOct2SnCl2, nOct3SnCl and Ph3SnCl would mainly yield…
Extended Investigation of the Aqueous Self-Assembling Behavior of a Newly Designed Fluorinated Surfactant
2009
The physicochemical behavior of the newly synthesized fluorinated 5-hydroxyamino-3-perfluoroheptyl-1,2,4-oxadiazin-6-one (PFHO) surfactant was investigated. Thermal analysis showed that the pure surfactant is thermally stable under an inert atmosphere to 135 degrees C, which is several degrees higher than the melting point (99 degrees C). PFHO is rather active at the water/air interface where it assumes a standing up configuration. It exhibits an enhanced self-assembling behavior; accordingly, the critical micellar concentrations at some temperatures are 2 orders of magnitude lower than those of a similar surfactant having the same phobicity, such as sodium perfluorooctanoate. Even in the d…
Characterisation of humic substances by acid catalysed transesterification
2002
Abstract The chemical composition of low molecular weight moieties linked to the core structures of humic substances (HS) are of substantial importance for the understanding of the chemical structures and mode of interactions of HS with other substances in the environment. In this study a novel approach to characterise certain low molecular weight compounds bound to HS is suggested. The method includes transesterification (TE) of ester and amide bound structures, and esterification (E) of free carboxylic groups using acid catalysed methanolysis followed by gas chromatography (GC)–mass spectrometry (MS) and GC-FID analysis. Methanolysis of five HS of different origin, demonstrated the presen…
FIA-fluorimetric determination of adrenaline in pharmaceutical formulations by oxidation with molecular oxygen
1998
The fluorimetric determination of adrenaline is carried out in a continuous-flow assembly and by means of the molecular dissolved oxygen. The sample solution merges with an NaOH stream, then the resulting mixture is heated at 73 °C and led to the flow-cell of the fluorimeter. The flow-assembly is very simple and the procedure is quick (107 samples h−1) reproducible (R.S.D. 0.6%), selective and suitable to be applied to determination of adrenaline in formulations. Calibrations graph are linear over the ranges 0.05–15 and 20–40 mgl−1.
Simultaneous Determination of Adrenaline and Noradrenaline by First Derivative Spectrophotometry in a Fia Assembly
1996
Abstract This article deals with the design of an unsegmented-flow injection manifold for the simultaneous determination of adrenaline and noradrenaline two structurally related compounds with overlapping spectra. An FIA manifold is proposed for the simultaneous determination in which the sample solution is directly injected into a carrier-reagent stream of aqueous NaOH. The selected wavelengths (first derivative) were 394 and 342 nm, for noradrenaline and adrenaline, respectively with an integration time of 0.4 s. The calibration graphs are linear over the range 2.0–30 ppm for both drugs. The method is applied to different synthetic mixtures of both drugs.
The use of utraviolet-visible spectrophotometry in the determination of average properties of nonylphenol ethylene oxide condensates
1983
Ultraviolet spectrophotometry is usd in the determination of average molecular weight (M), average degree of polymerization (X), the hydrophilic-lipophilic balance (HLB) and ethylene oxide percentage of nonylphenol ethylene oxide condensates. The method is based on determination of the absorptivity a, expressed in g lt-1 cm−1, from the absorbances measured at 275 nm for a series of dilutions of an aqeuous ethanolic solution (60:40, v/v/) of a given product, followed by numerical interpolation of this value in the expression a = f(HLB), log a = f(log M), and log a = f(log X). These expressions are obtained from reference samples or samples previously analyzed. The proposed method gives relat…
Sequestration of alkyltin(IV) cations by complexation with amino-polycarboxylic chelating agents
2013
Abstract The binding capacity of four amino-polycarboxylic ligands (APCs) [nitrilotriacetate (NTA), ethylenediamine- N , N , N′ , N′ -tetraacetate (EDTA), (S,S)-ethylenediamine- N , N ′-disuccinic acid (S,S-EDDS) and diethylenetriamine- N , N , N′ , N″ , N″ -pentaacetate (DTPA)] towards mono-, di- and tri-alkyltin(IV) cations [(CH 3 )Sn 3 + , (CH 3 ) 2 Sn 2 + , (C 2 H 5 ) 2 Sn 2 + , (CH 3 ) 3 Sn + or (C 2 H 5 ) 3 Sn + ] was studied, in aqueous solutions, by ISE-H + potentiometry, at I = 0.1 mol L − 1 (NaCl) and at T = 298.15 K. In all the systems R x Sn (4 − x)+ − APC (R = CH 3 or C 2 H 5 ) a strong 1:1 species is formed together with protonated, hydroxo and dinuclear complexes. The valu…