bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass spectrometry of derivatives of dicyclopentadienyltitanium dichloride I. Behavior in electron impact ionization mass spectrometry
Authors: Wang Fu , Fang Ming , Wu Wannian , Chen Xuehua , Huang Jielin 
Published: May 2005

AbstractElectron impact (EI) mass spectra of ten derivatives of dicyclopentadienyltitanium (IV) dichloride were studied. Fragmentation pathways were constructed and confirmed using daughter‐ion, parent‐ion and neutral‐species loss scan modes of MS/MS.
Characterization of over‐the‐counter cough/cold medications by liquid chromatography/electrospray mass spectrometry
Authors: Josephs Jonathan L. 
Published: May 2005

AbstractElectrospray ioniztion (ESI) high‐performance liquid chromatography/mass spectrometry (LC/MS) has been utilized for the characterization of the active ingredients in over‐the‐counter (OTC) cough and cold medications. The use of in‐source collision‐induced dissociation (CID) on a single quadrupole instrument produced spectra with characteristic fragment ions. The in‐source CID potential was rotated through different energies on alternate scans throughout the chromatographic run. The spectra across a given chromatographic peak were summed and averaged to give composite spectra which displayed molecular ions in addition to fragment ions, producing library searchable spectra of analytes with varying collisional stabilities, within a single chromatographic run. These spectra were then saved into a library which was created with the following OTC drugs, phenylpropanolamine, doxvlamine, pyrilamine, chlorpheniramine, brompheniramine, dextromethorphan, cyclizine, and clemastine. The active ingredients in commercial OTC remedies were detected and characterized using this created library. The method requires no derivatization and minimal sample preparation, is applicable to a range of analytes, and can be fully automated for multiple sample analyses.
Analysis of tilmicosin in swine liver extracts by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry
Authors: Kiehl Douglas E. , Kennington Allison S. 
Published: May 2005

AbstractTilmicosin is a semisynthetic macrolide antibiotic used in the treatment of respiratory disease in cattle and swine. The technique of liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI‐MS) was employed in an on‐line capacity for the analysis of tilmicosin in extracts from spiked swine liver. Increasing the potential in the cone/skimmer region of the ion source resulted in an increased abundance of unique structurally indicating fragment ions of tilmicosin. Three ions, [M + H]+and two diagnostic fragment ions were chosen for confirmation of the presence of tilmicosin in swine liver tissue extracts using the mass spectrometer in selected‐ion monitoring mode. The ion abundance ratios arising from any given combination of ions in data acquired from extracts of swine liver tissue spiked with tilmicosin at 5 and 10 ppm were within <10% of the corresponding mean standard abundance ratio, and duplicate sample analyses exhibited < 10% relative standard deviation. These results suggest the potential for the application of LC/APCI‐MS as a confirmatory technique for tilmicosin in swine liver.
Massive cluster ablation as preparation for organic secondary ion imaging
Authors: Dookeran N. N. , McMahon J. M. , Short R. T. , Todd P. J. 
Published: May 2005

AbstractA focused Cs+ beam was used to obtain secondary ion mass spectra and images from samples of stearic acid on gold before and after ablation by a beam of masive cluster ions. Ablation appears to have two effects on secondary ion emission. First, the number and intensity of peaks reflecting contamination are substantially reduced. Secondly, the absolute intensity of secondary ion current characteristic of the analyte increases. These features simplify mass spectra and improve contrast in the images obtained.
Chemical composition of wood casks for wine ageing as determined by pyrolysis/gc/ms
Authors: Galletti Guido C. , Carnacini Alberta , Bocchini Paola , Antonelli Andrea 
Published: May 2005

AbstractOak and chestnut cask staves were planed to a depth of one centimeter, collecting a sample every millimeter. The samples were ground and subjected to pyrolysis/gas chromatography/mass spectrometry in order to determine their composition. Thirty‐six compounds were identified, including a series of typical lignin phenolics commonly considered responsible for wine taste. All ions found in a previous pyrolysis/mass spectrometry study of oak wood and related to good quality whisky were confirmed in the mass spectra of the pyrolysis fragments specific for polysaccharides and lignin recorded in the present work. Compared to chestnut wood, oak wood showed significantly higher lignin and syringyl unit content and less variability as to lignin composition with depth.
High‐flow liquid chromatography/mass spectrometry interface using a parallel ion spray
Authors: Hiraoka K. , Fukasawa H. , Matsushita F. , Aizawa K. 
Published: May 2005

AbstractBy positioning the capillary of the ion spray parallel to the ion sampling orifice, several advantages have been found compared to the conventional perpendicular ion spray, e.g., higher sensitivity, stable operation, practically no contamination of the ion sampling orifice, and higher liquid flow rates up to 4 mL/min. This is due to the fact that while the charged fine liquid droplets are deflected towards the ion sampling orifice, the larger liquid droplets with lower charge density are entrained in the nebulizer gas jet and they are carried away outside the ion sampling system. With higher liquid flow rates (e.g. ⩾500 μL/min), the start of corona discharge does not result in a drastic decrease in the signal intensities of ions originating from sample solution. In electrospray experiments, it has also been found that the parallel spray gives better performance than the perpendicular one.
Sequencing peptides without scanning the reflectron: Post‐source decay with a curved‐field reflectron time‐of‐flight mass spectrometer
Authors: Cordero Marcela M. , Cornish Timothy J. , Cotter Robert J. , Lys Ihor A. 
Published: May 2005

AbstractA time‐of‐flight mass spectrometer has been developed using a reflectron in which the voltages placed on the lens elements correspond to a function describing the arc of a circle. This curved‐field reflectron enables acquisition of focused product‐ion mass spectra at a single reflectron voltage. In this paper, we present results from this instrument for the amino acid sequencing of several peptides and describe the method of mass calibration.
Comparison of the mass spectrometric behaviour of fluorinated ethers and sulphides
Authors: Favretto D. , D'Alpaos M. , Traldi P. , Bégué J. P. , Bonnet‐Delpon D. , Rock M. H. 
Published: May 2005

AbstractThe mass spectrometric behaviour of two pairs of fluorinated vinyl‐ and allyl‐ethers and thioethers has been studied in detail with the aid of metastable ion data and accurate mass measurements. Clear differences have been observed between the two sets of compounds; while for the ethers the McLafferty rearrangement with ethylene loss represents a highly favoured decomposition route, for the thioethers the loss of the ethyl radical is preferred. Some decomposition routes, common to all the compounds examined, suggest the presence of hydrogen atom bridging between carbon and fluorine atoms. Theoretical calculations have shown that such a quasi CHF structure is already present in the neutral molecule in its ground state.
Molecular complexes of cyclodextrins: Application of ion‐spray mass spectrometry to the study of complexes with selected nitramines
Authors: Bakhtiar Ray , Bulusu Suryanarayana 
Published: May 2005

AbstractComplex formation of the important nitramines, RDX, HMX and TNAZ with α‐, β‐, and γ‐cyclodextrins (CDs) was studied using ion‐spray mass spectrometry (IS‐MS). Complexations between β‐CD/TNAZ, β‐CD/RDX, γ‐CD/RDX, and γ‐CD/HMX were detected in the gas phase by this technique. Control experiments using α‐CD and TNAZ did not lead to a detectable molecular association, which is in accord with the previously reported NMR data. In addition, none of the nitramines showed any complex formation with the non‐cyclic sugar, maltohexose. The IS‐MS results are in agreement with the previously reported conclusions from proton nuclear magnetic resonance spin‐lattice relaxation time measurements.
Fully automated sample preparation and electrospray mass spectrometry analysis
Authors: Raso R. , Fehlhaber H.‐W. 
Published: May 2005

AbstractA fully automated sample preparation–mass spectrometry system has been described which prepares samples prior to electrospray mass spectrometry analysis, injects the samples, and acquires and processes the data. Fifty samples can be analysed without operator intervention within 8 hours. This type of system ensures optimum use of both the mass spectrometer, which can be in operation 24 hours per day, and the mass spectroscopist, who can concentrate on more challenging samples and spectral interpretation. The laboratory robot system used can be easily adapted for different types of sample preparation and other methods of analysis. For example, in addition to a spectrum exhibiting mainly protonated or deprotonated molecular ions, data could be acquired concurrently with a higher cone voltage, or under tandem mass spectrometry conditions, to generate structurally informative fragment ions. This sample preparation method has been adapted to encompass a variety of samples such as proteins and nucleic acids.
The use of amine base to enhance the sensitivity of electrospray mass spectrometry towards complex polysulphonated azo dyes
Authors: Ballantine James A. , Slater Paul S. , Games David E. 
Published: May 2005

AbstractElectrospray ionization mass spectrometry was employed in the detection of polysulphonated azo dye sodium salts, and other compounds containing the sulphonate‐sodium ion group [SO +Na]. Before amine addition, the polysulphonated azo dyes produced low intensity ions. Spectra were obtained in both positive‐ and negative‐ionization modes, the negative mode giving the best results. The typical spectrum of a dye depended on the number of cations associated to the compound. Each compound displayed a series of ion peaks which were the result of varied amount of cation–proton exchange during the ionization process. The number of protons observed to bind to a compound anion with (n) sodium cations simultaneously removed depended on the charge (z) carried by each ion within an ion series. We have found that the addition of an amine base sensitizes polysulphonated azo salts towards electrospray ionization mass spectrometry. We propose that the addition of the amine base assists the total removal of cations. This selectively enhances the intensity of the acid ion peaks of each ion series, by accumulating each peak present within z‐charged ion series into a single intense peak. The percentage increase in the intensity of the acid ion peaks was observed in most cases to follow the gas‐phase proton affinity of the applied amine base. Preliminary results have also indicated that a correlation exists between the percentage increase in the intensity of acid ion peaks and the number of cations originally associated to each compound.
Secondary ion mass spectrometric studies on the formation mechanism of IrO2/TiO2‐based coatings
Authors: Kristóf J. , Daolio S. , Piccirillo C. , Facchin B. , Pagura C. 
Published: May 2005

AbstractThe formation mechanism of an IrO2/TiO2 film electrode has been studied by secondary ion mass spectrometry (SIMS). A coating mixture with the composition 50% Ir+50% Ti prepared on a titanium support from an isopropanolic solution of hydrated iridium chloride and titanium bis‐2,4‐pentanedionate precursors was heated to specified temperatures and analysed by SIMS. Concentration depth profiles of some selected species (e.g. Cl−, O−, ClO−, TiO+, Ir+, IrO, TiO, CH, C2H, OH−) were used to follow the process of film evolution. Segregation phenomena resulting in the increased dispersity of the noble metal on the surface were identified. The results are in accordance with—and complementary to—those of former measurements by combined thermoanalytical, mass spectrometric and emission Fourier transform infrared (FTIR) techniques.
Characterization of acetals by means of capillary gas chromatography/mass spectrometry
Authors: De La Ruelle Hugo , Klok Jaap , Rinken Marian , Felix Mark 
Published: May 2005

Abstracti‐Butylvinylether and diethyleneglycol‐n‐butyl ether (Dowanol‐DBTrade name of The Dow Chemical Company.
) were reacted under mild acidic conditions to yield acetals. This report deals with the identification of the reaction products by means of gas chromatographic separation followed by mass spectrometric analysis in both electron impact and chemical ionization modes. Consultation of the standard NIST library (50k spectra) revealed that none of the spectra of the acetals in this study were present. A more elaborate study of fragmentation patterns was therefore initiated. The fragmentation patterns of the reaction products in electron impact ionization mode are discussed in detail. During ammonia chemical ionization, typical [M+NH4+26]+ ions are observed for 4,6‐dioxa‐2,5,8‐trimethylnonane. A hypothesis for this phenomenon is presented.
Detection of high molecular weight starburst dendrimers by electrospray ionization mass spectometry
Authors: Schwartz Brenda L. , Rockwood Alan L. , Smith Richard D. , Tomalia Donald A. , Spindler Ralph 
Published: May 2005

AbstractAn entire series of Starburst polyamidoamine (PAMAM) dendrimers consisting of generations 1 through 10 (G1–10) have been studied by positive‐ion electrospray ionization mass spectrometry (ESI‐MS) using an extended m/z range quadrupole mass spectrometer. Charge‐state distributions were detected as high as m/z 12 000 for the generation 10 dendrimer, having a theoretical molecular weight of 1 megadalton and containing approximately 93 maximum positive charges on the molecule. Accurate molecular weight determinations of the smaller generation dendrimers (G1–3, Mr ∼ 1.4kDa to 6.9kDa) were obtained using a commercial triple quadrupole instrument. The unit resolution ESI mass spectra provide information on the number of incomplete reactions which may occur during polymer synthesis. The extent of gas‐phase charging observed by ESI‐MS on the entire series of macromolecules was found to exhibit a linear relationship to M, consistent with theoretical models prediciting a spherical ion structure with maximum charging controlled by Coulombic effects.
The characterization of synthetic polymers by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Cottrell J. S. , Koerner M. , Gerhards R. 
Published: May 2005

AbstractMolecular weight parameters for synthetic polymers are defined and their determination by matrix‐assisted laser desorption/ionization (MALDI) is described. In particular, details of matrix materials that are suitable for this type of measurement are provided. The availability of increased instrumental resolution provides a simple means of endgroup identification for some synthetic polymers.
Analysis of linear oligogalacturonic acids by negative‐ion electrospray ionization mass spectrometry
Authors: Xie Mei , Giraud Denis , Arpino Patrick , Bertheau Yves , Casetta Bruno 
Published: May 2005

AbstractLinear oligogalacturonic acids (1,4‐linked α‐D‐galacturonic acid oligomers), obtained by partial acid hydrolysis of orange polygalacturonides, were studied by negative‐ion electrospray ionization mass spectrometry, without prior sample derivatization. After preparative separation using high‐resolution anion‐exchange chromatography, some fractions enriched in uronic acids were desalted, transferred into a methanol+water solution adjusted to pH 10, and directly submitted to electrospray ionization mass spectrometry in the negative‐ion recording mode. Clear molecular mass assignments of the oligomers, covering a degree of polymerization between 4 and 7, were obtained.
Experimental study of the efficiency of storage in an RF ion trap
Authors: Vedel M. , Rocher J. , Knoop M. , Vedel F. 
Published: May 2005

AbstractN+ ions were stored in a home‐made ion trap. The apparatus allows the systematic characterization of ion motion in the presence of anharmonicities due to geometric defects, or to a smaller degree, due to the space charge. Enrichment of the spectrum of the motion frequencies and drastic reduction of the storage capability occur due to radial‐axial couplings. The paper presents experimental observations of these effects.
Chemometric classification of some european wines using pyrolysis mass spectrometry
Authors: Montanarella Luca , Bassani Maria Rosa , Bréas Olivier 
Published: May 2005

AbstractThe application of Curie‐point pyrolysis mass spectrometry (Py/MS) to 33 certified wine samples from different regions of Spain, France and Italy is reported. The resulting mass spectra were submitted to principal component analysis, canonical variates analysis and cluster analysis producing a final dendrogram, using average linkage clustering. A good classification was achieved according to large geographical areas (country of origin), while no correlation was found to grape species or to local areas of cultivation. The same data were submitted to artificial neural networks analysis using the back‐propagation algorithm and dividing the data into a training and a test data set. More than 90% of the test wine samples were correctly identified according to their country of origin after training of the artificial neural network. Again no correlation was found between pyrolysis mass spectra and grape species or area of cultivation. Nevertheless, the technique could be applied to rapid screenings of wine samples for the tentative identification of country of origin. In combination with other techniques (IR‐MS, NMR) it can give complementary information about the samples and their regions of origin.
Autoradiographic localization of 3H‐paroxetine‐labeled serotonin uptake sites in rat brain
Authors: De Souza Errol B. , Kuyatt Brian L. 
Published: May 2005

AbstractParoxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H‐paroxetine; 3H‐paroxetine binding in slide‐mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H‐paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H‐paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of the thalamus, and the islands of Calleja. High concentrations of 3H‐paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H‐paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H‐paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4‐methylenedioxyamphetamine caused large decreases in 3H‐paroxetine binding. The autoradiographic distribution of 3H‐paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin.
The mobility of anthropogenic129I in a shallow sand aquifer at Sturgeon Falls, Ontario, Canada
Authors: Renaud Robert , Clark I. D. , Kotzer T. G. , Milton G. M. , Bottomley D. J. 
Published: May 2005

SummaryThe transport and partitioning of129I has been examined for a shallow groundwater flow system at Sturgeon Falls in northeastern Ontario. Recharge into a sandy surficial postglacial deltaic aquifer occurs in the vicinity of a seasonally-wet boreal forest. Concentrations of stable iodine,129I, tritium, radiocarbon, stable isotopes and major ions were measured on samples of groundwater and precipitation. The present-day tritium profile delineates the position of the early 1960's above-ground nuclear weapons pulse at a depth of approximately 12 m.The concentrations of stable iodine for groundwaters above, near and below the above-ground nuclear weapons pulse range from 0.07 to 1.7 ppb. Over that same interval129I concentrations decreased from 1.9 × 106atoms/L at 9 m, to approximately 1.9 × 105atoms/L in tritium-depleted waters at 35 m, below the present-day depth of the recharging above-ground nuclear weapons peak at approximately 12.7 m. No substantial increases in the levels of129I were evident in waters sampled near the location of the above-ground nuclear weapons peak.The129I values in the lower aquifer are 1 to 2 orders of magnitude greater than published estimates of pre-bomb129I (103to 104atoms/L), and indicate contribution of129I from the fissiogenic decay of238U in the basal granite bedrock or from leaching of129I from the aquifer grains.A precipitation sample collected at Sturgeon Falls had concentrations of stable iodine and129I of 0.2 ppb and 8.5 × 107atoms/L, respectively. Concentrations of129I in Sturgeon Falls groundwaters are lower than those reported in other studies in central Canada, suggesting that the levels of129I in these groundwaters may have been attenuated by complexation or ion exchange with organic materials in the near-surface soil horizons. Such processes have been documented during a previous study on the behavior of129I in a shallow aquifer near a low-level, radioactive waste management area.Along a 30 cm soil profile at piezometer nest 28 at the Sturgeon Falls study site, the concentrations of129I ranged from approximately 4.3 × 108atoms/g in the uppermost soil litter layer to 5.6 × 107atoms/g in the siltier bottom soil horizons. Over that same profile, stable iodine varied from 4.7 ppm in the upper layers to 3.9 ppm in the lower layers.
GaAs/AlGaAs-Quantenkaskaden-Laser (GaAs/AlGaAs Quantum Cascade Lasers)
Authors: Höfling Sven , Reithmaier Johann P. , Forchel Alfred 
Published: May 2005

Abstract
Es wurden Quantenkaskaden-Laser für den 10-μm-Spektralbereich hergestellt. Zur Miniaturisierung, Verbesserung der Bauelementeigenschaften und Erzielung monomodiger Emission wurden Laser mit eindimensionalen photonischen Kristallstrukturen in Form von tiefgeätzten Bragg-Spiegeln entwickelt. Es wurde erstmals erfolgreich nahezu gitterangepasstes GaInNAs auf GaAs-Substraten bei 590 °C aufgewachsen, womit eine wesentliche Erhöhung des Ladungsträgereinschlusses ermöglicht wird.