Search results for "Spectroscopy"
showing 10 items of 10293 documents
Surfactant self-assembling in the gas phase: bis(2-ethylhexyl)-sulfosuccinate divalent metal ion anionic aggregates
2012
RATIONALE Investigation of fundamental aspects driving surfactant self-assembling and of the capability of including guest molecules or ions in their micellar aggregates is an exciting research field for theoretical and technological reasons. In this light, assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ion chlorides have been investigated in the gas phase by electrospray ionization mass spectrometry in negative ion mode, tandem mass spectrometry and energy-resolved mass spectrometry. METHODS Water/methanol solutions of AOTNa and chloride salts of nickel, magnesium, calcium and manganese, with different AOTNa/metal salt ratios, w…
Rapid classification of enzymes in cleaning products by hydrolysis, mass spectrometry and linear discriminant analysis
2008
A method for the rapid classification of proteases, lipases, amylases and cellulases used as enhancers in cleaning products, based on precipitation with acetone, hydrolysis with HCl, dilution of the hydrolysates with ethanol, and direct infusion into the electrospray ion source of an ion-trap mass spectrometer, has been developed. The abundances of the ([M+H]+ ions of the amino acids, from the hydrolysates of both the enzyme industrial concentrates and the detergent bases spiked with them, were used to construct linear discriminant analysis models, capable of distinguishing between the enzyme classes. For this purpose, the variables were normalized as follows: (A) the ion abundance of each …
Infusion mass spectrometry as a fingerprint to characterize varnishes in oil pictorial artworks.
2007
Mass spectrometry methodology to characterize drying oil used as binding media and varnishes in pictorial artworks, prior to conservation or restoration treatment, is proposed. The analytical treatment requires prior basic hydrolysis of the samples to release the fatty acids : caprylic, pelargonic, capric, sebacic, azelaic, suberic, eicosanoic, lauric, mirystic, palmitic, linolenic, linoleic, oleic and stearic, followed by separation from the matrix by a hexane/water extraction. After removing the solvent, the remaining solid is dissolved in potassium hydroxide, propanol and methanol. The mixture is directly infused into a mass spectrometer without any previous derivatization or separation …
Positive and negative electrospray ionization-collision-induced dissociation of sulfur- containing zwitterionic liquids.
2011
The mass spectrometric properties of several (1,2-dimethyl-1 H-imidazol-3-ium-3-yl)-alkane-1-sulfonates (alkane=ethyl, propyl and butyl) are investigated in this study. These substances, named zwitterionic liquids (ZILs), were synthesized using classical transformations and analyzed in positive and negative electrospray ionization mode using collision-induced dissociation (0–50 eV). We have also performed regioselective deuterium labeling of the alkyl chain of 3-(1,2-dimethyl-1 H-imidazol-3-ium-3-yl)-propane-1-sulfonates. Thus, the mass spectra of isotopically-labeled compounds were used for the confirmation of fragmentation pathways of ZILs. Briefly, the data obtained in this study show t…
Characterization of interaction between tricyclic structures containing pharmaceuticals, their models and humic substances.
2011
Their persistence and wide consumption identify pharmaceuticals as “emerging pollutants”. The complexation of pharmaceuticals containing adamantine ring structures and their model substances with humic acids (HA) of different origins was compared using fluorescence spectroscopy as a function of pH, humic acid concentration, ionic strength, and molecular mass of HA. Binding constants between the studied pharmaceuticals and humic acids were calculated. A combination of dynamic and static quenching processes as indicated by nonlinear Stern-Volmer plots and high Kd values were positively correlated with the concentration of carboxyl groups in the studied humic acids. For basic functional group-…
Mesoporous silica-based materials for use in electrochemical enzyme nanobiosensors
2012
Abstract Biology and medicine have seen great advancements in the development of enzyme nanobiosensors capable of characterizing and quantifying biomolecules. We provide an overview of mesoporous silica (MPS)-based enzyme nanobiosensors developed for biological and medical applications, and we describe significant advances in these technologies. We review progress in constructing high-performance electrochemical enzyme biosensors. We also discuss: • MCM-41 and SBA-15-modified and MPS composite electrodes for enzyme biosensing; • incorporation of biorecognition elements into MPS material electrodes for enzyme biosensing; and, • MCM-41 and SBA-15-supported electrocatalytic MPS-based electroch…
New Triterpenoid and Ergostane Glycosides from the Leaves of Hydrocotyle umbellata L.
2011
Two new triterpenoid glycosides, together with two new ergostane glycosides, umbellatosides A–D (1–4, resp.), have been isolated from the leaves of Hydrocotyle umbellata L. Their structures were established by 2D-NMR spectroscopic techniques (1H,1H-COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectrometry as 3β,22β-dihydroxy-3-O-[α-L-rhamnopyranosyl-(12)-β-D-glucuronopyranosyl]olean-12-en-28-oic acid 28-O-β-D-glucopyranosyl ester (1), 3-O-[α-L-rhamnopyranosyl-(12)-β-D-glucuronopyranosyl]oleanolic acid 28-O-β-D-glucopyranosyl ester (2), (3β,11α,26)-ergosta-5,24(28)-diene-3,11,26-triol 3-O-(β-D-glucopyranosyl)-11-O-(α-L-rhamnopyranosyl)-26-O-β-D-glucopyranoside (3), and (3β,11α,21,26)-ergosta…
Vapor-phase testing of the memory-effects in benzene- and toluene-imprinted polymers conditioned at elevated temperature.
2013
Abstract The preparation of polymers imprinted with common aromatic solvents such as benzene and toluene is an under-exploited subject of research. The present study was aimed at the understanding of whether true solvent memory effects can be achieved by molecular imprinting, as well as if they are stable at elevated temperature. A set of copolymers, comprising low and high cross-linking levels, was prepared from four different combinations of functional monomer and cross-linker, namely methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA), methyl methacrylate (MMA)/EGDMA, MAA/divinyl benzene (DVB) and MMA/DVB. Each possible combination was prepared separately in benzene, toluene an…
Efficiency Boosting of Surfactants with Poly(ethylene oxide)-Poly(alkyl glycidyl ether)s: A New Class of Amphiphilic Polymers
2020
Twenty years ago, it was found that adding small amounts of amphiphilic block copolymers like poly(ethylene propylene)-co-poly(ethylene oxide) (PEP-b-PEO) to microemulsion systems strongly increases the efficiency of medium-chain surfactants to solubilize water and oil. Although being predestined to serve as a milestone in microemulsion research, the effect has only scarcely found its way into applications. In this work, we propose new types of efficiency boosters, namely, poly(ethylene oxide)-poly(alkyl glycidyl ether carbonate)s (PEO-b-PAlkGE) and their "carbonated" poly(ethylene oxide)-poly(carbonate alkyl glycidyl ether) analogs. Their synthesis via anionic ring-opening polymerization (…
Plutonium(III) complexation by humic substances studied by X-ray absorption fine structure spectroscopy
2006
Abstract We determined structural parameters for the near-neighbor surrounding of plutonium(III) in complexes with humic and fulvic acids at pH 1 and for the purpose of comparison also for the plutonium(III) aquo ion by means of X-ray absorption fine structure (XAFS) spectroscopy. It could be shown that in the complexes with humic substances as well as in the plutonium(III) aquo ion sample the trivalent oxidation state of plutonium was stable within the time of the experiment. In the humate and fulvate complexes, the plutonium(III) is surrounded by about eight oxygen atoms with an average Pu–O distance of 2.48 ± 0.02 A. The structural parameters determined for plutonium(III)–humate and –ful…