bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immobilized human serum albumin: Liquid chromatography/mass spectrometry as a method of determining drug–protein binding
Authors: Tiller Philip R. , Mutton Ian M. , Lane Stephen J. , Bevan Christopher D. 
Published: May 2005

AbstractA liquid chromatography/mass spectrometry methodology is described that enables the simultaneous estimation of the individual protein‐binding affinities of a mixture of compounds. This approach has proved to be robust and enables a series of molecules to be ranked according to their protein‐binding affinities within 20 minutes.
Tandem mass spectrometry analysis of synthetic opioid peptide analogs
Authors: Tseng Jih‐Lie , Yan Lin , Fridland Genevieve H. , Desiderio Dominic M. 
Published: May 2005

AbstractFive synthetic opioid peptides that were designed to have specific opioid receptor‐binding properties were studied by low energy collision‐induced dissociation (CID) tandem mass spectrometry (MS/MS). The MS/MS data are required for the analysis of those peptides in ovine plasma in a study to determine the placental transfer of the peptide to the fetus. The synthetic enkephalin‐related peptides were: Tyr‐D‐Arg‐Phe‐Lys‐NH2, (DALDA), N,N‐diallyl‐Tyr‐Aib‐Aib‐Phe‐Leu‐OH, (ICI 174,864), Tyr‐D‐Thr‐Gly‐Phe‐Leu‐Thr, (DTLET), magnified image. Liquid secondary ion mass spectrometry (LSIMS) was used for sample desorption‐ionization, and a hybrid (E1BE2qQ) tandem mass spectrometer was used to collect the product‐ion spectra. A protonated molecule ion, [M + H]+, was observed for each peptide. Amino acid sequence‐determining fragment ions were produced by CID and collected by MS/MS for the three linear peptides, and also for the two disulfide‐bond‐containing peptides in their unreduced and dithiothreitol (DTT)‐reduced forms. The detection level for the [M + H]+ ion of DTLET was ca. 3 pmol; and the stabilities of the CTAP and ICI analogs in plasma were studied.
Possible applications of an external resonant circuit in Fourier transform ion cyclotron resonance
Authors: Gorshkov Michael V. , Kouzes Richard T. 
Published: May 2005

AbstractThe narrow‐band cooling of ion motion in the trap of a Fourier transform ion cyclotron resonance mass spectrometer (FTICR) using an external parallel resonant circuit is considered. The parameters of the circuit necessary for effective cooling of both axial and cyclotron ion motion are estimated. It is shown that the use of a resonant circuit may be helpful in studying the highly charged heavy ions produced in experiments with electrospray ionization combined with FTICR.
Excitation of neutral molecules: Probing the dynamics by translational energy spectrometry
Authors: Krishnamurthy M. , Mathur D. 
Published: May 2005

AbstractHigh‐resolution translational energy spectroscopy has been applied to the study of collision‐induced excitation of neutral diatomic and polyatomic molecules using molecular projectile ions. Techniques to simulate the experimentally observed energy loss spectra are explored and information regarding the relative oscillator strengths to different electronic states of the neutral targets has been obtained. The effects of changing the quantal description of the projectile are studied and the results are understood within the domain of wavefunction overlaps. Concomitant calculations of the wavefunction overlap of the highest occupied molecular orbitals of the collision partners yield results which are consistent with the experimental observations.
Characterization of 1,3‐dioxolanes upon positive‐ion chemical ionization
Authors: Aubert C. , Rontani J.‐F. 
Published: May 2005

AbstractPositive‐ion chemical ionization (CI) mass fragmentations were studied in the case of different 1,3‐dioxolanes. The formation in methane CI mass spectra of interesting fragment ions allowing the characterization of their parent carbonyl compounds and diols is discussed and some mechanisms (supported by D2O CI analyses) are proposed in order to explain these fragmentations.
A comparison of the combination of fast‐atom bombardment with tandem mass spectrometry and of gas chromatography with mass spectrometry in the analysis of a mixture of kaempferol, kaempferide, luteolin and oleouropein
Authors: Baracco Andrea , Bertin Giorgio , Gnocco Elia , Legorat Mauro , Sedocco Silvia , Catinella Silvia , Favretto Donata , Traldi Pietro 
Published: May 2005

AbstractTwo different approaches, i.e. fast‐atom bombardment tandem mass spectrometry and gas chromatography combined with mass spectrometry (GC/MS) have been employed for the characterization of a mixture of biologically relevant polyphenols (kaempferide, kaempferol, luteolin and oleouropein). The best results have been achieved by the first approach which allows an easy structural identification of the different compounds, also in the presence of isomers. GC/MS of the trimethylsilyl derivatives leads to a complex chromatogram due to the presence of derivatives exhibiting a different level of silylation; the only species related to oleouropein are due to pyrolysis products (silylated fragments of sugars) and there is no evidence for the related silylated aglycone.
On‐line combination of micellar electrokinetic chromatography and mass spectrometry using an electrospray–chemical ionization interface
Authors: Takada Yasuaki , Sakairi Minoru , Koizumi Hideaki 
Published: May 2005

AbstractMicellar electrokinetic chromatography/mass spectrometry (MEKC/MS) using an electrospray–chemical ionization (ES‐CI) source is described. The interface between micellar electrokinetic chromatography and mass spectrometry consists of an electrospray‐type nebulizer and an atmospheric pressure chemical ionization source that uses a needle electrode. Aromatic amines (aniline, p‐nitroaniline, and 1‐naphthylamine) are analysed by MEKC/MS, using a phosphate buffer that includes 20 mM sodium dodecyl sulfate (SDS), and protonated molecular ions of the samples are clearly recorded on the ion electropherograms. The results show that the ES‐CI technique is very promising as an MEKC/MS interface since MEKC/MS uses a high concentration of nonvolatile salts and surfactants.
Identification of denatured double‐stranded DNA by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Benner William H. , Horn David , Katz Joe , Jaklevic Joseph 
Published: May 2005

AbstractWe created double‐stranded DNA (dsDNA) by annealing synthetic oligonucleotides and used matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry to measure the difference in molecular weight of the complementary strands after denaturation. Refined sample preparation and deliberate rectilinear construction of a linear mass spectrometer produced a mass resolution exceeding 1000 for single‐stranded DNA. We present methodologies and demonstrate the potential for analysing dsDNA by determining the mass of the complementary strands.
A fully integrated trap‐membrane inlet mass spectrometry system for the measurement of semivolatile organic compounds in aqueous solution
Authors: Leth Mads , Lauritsen Frants R. 
Published: May 2005

AbstractA novel procedure to perform a membrane‐inlet mass spectrometry experiment is presented, which allows semi‐volatile organic compounds to be preconcentrated inside the membrane, before they are thermally released into the ion source. The method uses a standard membrane inlet with a tubular silicone membrane passing straight through the ion source of the mass spectrometer. A long slit in the ion source parallel to the membrane allows electrons from the filament to continuously bombard the membrane surface. The membrane is kept cold by a continuous flow of water or sample solution passing through the inlet. However, during a short interruption of the flow, the membrane is rapidly heated by the electron bombardment and organic compounds dissolved in the membrane are thermally released into the ion source. In this fashion a desorption peak is obtained. Using the areas of the desorption peaks, we have been able to detect semi‐volatile, hydrophobic organic compounds (boiling points above 200 °C) in aqueous solution at low and sub parts‐per‐billion levels. In general, the detection limits were 10–100 times lower than previously published results, where membrane‐inlet mass spectrometry has been used for the detection of the same compounds. Good linearity over 3 orders of magnitude was obtained and the standard deviation was 5%.
Fragmentation and intramolecular cyclization in cyclopentane‐4,5‐fused 2‐N‐phenyliminoperhydro‐1,3‐oxazines and related thiazines under electron impact ionization
Authors: Oksman Pentti , Pihlaja Kalevi , Fülöp Ferenc , Bernáth Gábor 
Published: May 2005

AbstractThe influence of cyclopentane fusion on the fragmentation behaviour of 1,3‐oxazines and related thiazines was studied. The differences observed in the rearrangement reactions between the hydrogen atom at the ortho position of the aromatic ring and one of the hetero atoms in the cyclohexane ring were also investigated. These rearrangements occur if the cyclohexane ring contains an electrophilic atom and the carbon atom next to it is substituted by a benzyl or arylamino group. The compounds examined were cis and trans isomers of the title compounds substituted with methyl and benzyl (in the latter case only the cis isomers) on the ring nitrogen. All the compounds exhibited a large [M  H]+ ion peak which decreased with increasing size of the substituent. This indicates an intramolecular cyclization prior to further fragmentation of the molecule. Methyl substitution seems to change the character of this intramolecular cyclization. The main routes of fragmentation resemble those of the cyclohexane‐fused analogues more than those of the corresponding 5,6‐fused compounds. The stereoisomers fragment so similarly that they cannot be distinguished from each other, except in the case of methyl substituted oxazines.
Sensitive detection and structural characterization of trimethyl(p‐aminophenyl)‐ammonium‐derivatized oligosaccharides by electrospray ionization–mass spectrometry and tandem mass spectrometry
Authors: Okamoto Masahiko , Takahashi Ken‐Ichi , Doi Tadashi 
Published: May 2005

AbstractMass spectrometric methodologies which use electrospray ionization (ESI) for oligosaccharide structural determination and which are linked to classical procedures, such as reductive amination, have been established. Several derivatives of a model oligosaccharide were prepared and their ionization efficiencies in electrospray ionization (ESI) and fast‐atom bombardment (FAB) mass spectrometry were investigated. The trimethyl‐(p‐aminophenyl)ammonium (TMAPA) derivatives showed extremely high sensitivity in positive‐ion ESI–MS and gave Y‐ and Z‐series sequence ions by ESI tandem mass spectromety (MS/MS). This study suggests that TMAPA‐derivatized oligosaccharides used in ESI‐MS and ESI‐MS/MS would be effective for structural characterization of oligosaccharides that are available only in limited quantities.
Determination of multiply labeled serine and glycine isotopomers in human plasma by isotope dilution negative‐ion chemical ionization mass spectrometry
Authors: Culea Monica , Hachey David L. 
Published: May 2005

AbstractA gas chromatography/negative‐ion chemical ionization mass spectrometry method is presented to measure the isotopic enrichment of multiple serine and glycine isotopomers. The amino acid N‐heptafluorobutyryl n‐propyl ester derivatives were used. The method had good analytical linearity between 10 and 800 μg mL−1 and both precision and accuracy were 5% for plasma amino acids. Sensitivity permitted analysis of 100 pg amino acid on column. The method was applied to metabolic studies of the serine to glycine interconversion in humans. (α‐15N)serine and (1,2‐13C2)glycine were given as a single intravenous bolus to six healthy male subjects. Plasma concentration of glycine and serine were determined after addition of (α‐15N,1,2,3‐13C3) serine and (α‐15N,1,2‐13C2)glycine as internal standards to 500 μL of plasma. Since glycine and serine are rapidly interconverted by hepatic serine hydroxymethyl transferase, the resultant tracer spectrum requires deconvolution of the enrichment of four isotopomers of each amino acid. Deconvolution of the ion abundance ratios to yield tracer‐to‐tracee ratios for each isotopomer was done using Brauman's least squares approach.
Ionophores: Potential screening via supercritical‐fluid chromatography combined with mass spectrometry and tandem mass spectrometry
Authors: Ramsey E. D. , Berry A. J. , Lawrence S. D. , Games D. E. , Startin J. R. 
Published: May 2005

AbstractA variety of ionophores have been studied by packed column supercritical‐fluid chromatography combined with mass spectrometry. One of the ionophores, lasalocid, provided particularly good multiple‐reaction monitoring signal‐to‐noise responses when analysed by tandem mass spectrometry and this approach shows considerable potential for the analysis of this compound in medicated animal feeds. A capillary supercritical‐fluid chromatograph has been interfaced to an unmodified benchtop quadrupole mass spectrometer and this combination has enabled the molecular weight determination of the sodium salt of an ionophore.
Mass spectrometric identification of N‐phenyllinoleamide metabolites in mouse peritoneal macrophages
Authors: Bioque G. , Abián J. , Bulbena O. , Roselló‐Catafau J. , Gelpí E. 
Published: May 2005

AbstractN‐Phenyllinoleamide (NPLA), the anilide of linoleic acid, has been regarded as a marker of the case oils associated with toxic oil syndrome, but the mechanisms of toxic injury remain enigmatic. Experimental data have related an increased systemic toxic effect of heated linoleic anilides to chemical structural modifications that might also be possible by in vivo metabolism; however, little is known about their metabolism. Taking into account that NPLA is a derivative of linoleic acid, a fatty acid that can be metabolized by lipoxygenase activity to a vast array of derivatives possessing biological activity, the objective has been to elucidate the oxidative metabolism of NPLA by mouse peritoneal macrophages, a cellular model with high lipoxygenase activity. Cells were incubated with 0.1 mM NPLA spiked with N‐phenyl[1‐14C]linoleamide. The metabolites were separated by high‐performance liquid chromatography and individually collected prior to GC/MS analysis. Identification of trihydroxy‐, monohydroxy‐ and epoxy‐derivatives of NPLA, suggests that this xenobiotic can be metabolized via the same oxidative processes as for linoleic acid. Furthermore, identification of the non‐amidated monohydroxylated and trihydroxylated derivatives of linoleic acid arising from NPLA suggests an amidase‐like activity with release of aniline and the free fatty acid. These results provide information about possible biological structures arising from NPLA, and open the way to evaluate the biological significance of these metabolites in the inflammatory reactions associated with toxic oil syndrome.
Liquid chromatography mass/spectrometry multiresidue determination of sulfonylureas after on‐line trace enrichment
Authors: Volmer Dietrich , Wilkes Jon G. , Levsen Karsten 
Published: May 2005

AbstractA multiresidue method was developed for the trace level determination of sulfonylurea herbicides in aqueous samples. The method employs on‐line solid‐phase extraction and electrospray and thermospray reversed‐phase liquid chromatography mass spectrometry. In combination with time‐scheduled selected‐ion monitoring, the method permits the detection of the sulfonylureas down to the 50–100 ng/L level with excellent recoveries of > 90% and reproducibilities between 2 and 8.5% for almost all of the investigated compounds. This improved method is superior to existing techniques because no special clean‐up step is necessary, and owing to the fast online preconcentration step, the technique can be used as a rapid screening and confirmatory method. The method can be used with either thermospray cr electrospray mass spectrometry, both of which provided mass spectra with at least three structure‐signficant ions necessary for an unambiguous identification in environmental samples.
Detection of ΔF508 mutation of the cystic fibrosis gene by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Ch'Ang L.‐Y. , Schell M. , Ringelberg C. , Tang K. , Matteson K. J. , Allman S. L. , Chen C. H. 
Published: May 2005

AbstractThe most common mutation of the cystic fibrosis gene is characterized by the deletion of three nucleotides that code phenylalanine in the 508 position of the cystic fibrosis transmembrane conductance regulator. We report the first measurements by matrix‐assisted laser desorption/ionization (MALDI) time‐of‐flight mass spectrometry for the ΔLF508 mutation in cystic fibrosis carriers and patients. Furthermore, in a blind test, results from the normal and ΔLF508 mutant alleles in 30 clinical samples based on MALDI mass spectrometry and on conventional gel analysis of the DNA were in total agreement. These results demonstrate the utility of MALDI mass spectrometry in the molecular diagnosis of mutant alleles and point to its potential use for ultra‐fast detection in large‐scale screening of DNA mutations.
Matrix‐assisted laser desorption/ionization mass spectrometry: Improved matrix for oligosaccharides
Authors: Mohr Martin D. , OlafBörnsen K. , Widmer H. Michael 
Published: May 2005

AbstractThe aim of this article was to study the influence of different matrix molecules on the quality of matrix‐assisted laser desorption/ionization mass spectra of oligosaccharides. An important criterion was the sample preparation, i.e. the crystallization process leading to the matrix from which the analytes were desorbed and investigated. Quality criteria were, among others, the resulting molecular peak intensity, the mass resolution, and the suppression of unwanted matrix peaks. It was found that a mixture of 2,5‐dihydroxy benzoic acid (DHB) and 1‐hydroxy isoquinoline (HIC) in a weight ratio of 3:1 was best suited for the analytical investigation of oligosaccharides. In addition, this matrix mixture was found to be quite tolerant against all kinds of buffers, salts, and even additives such as sodium dodecyl sulfate (SDS). Furthermore, we determined the different affinities of the alkaline metals to the carbohydrates and found that cesium and potassium ions ionize oligosaccharides about three times better than sodium ions and therefore have an important influence on the quantum yield.
Thermal decomposition kinetics of protonated peptides and peptide dimers, and comparison with surface‐induced dissociation
Authors: Meot‐Ner (Mautner) Michael , Dongré Ashok R. , Somogyi Árpád , Wysocki Vicki H. 
Published: May 2005

AbstractRate constants for the unimolecular decomposition of peptide monomer and dimer ions by thermal and surface‐induced dissociation (SID) are measured and compared. Rate constants for thermal dissociation are measured in a heated wide‐bore capillary flow reactor attached in front of the capillary leading into the mass spectrometer. Thermal decomposition of the leucine enkephalin ion (YGGFL)H+ is observed between 600 and 680 K with rate constants of 20–200 s−1, and yields many of the same fragments as SID at 35 eV, although with different relative intensities. The thermal decomposition yields the Arrhenius parameters Ea = 38.3 kcal/mol, log A = 15.7. The decomposition of the monomer and dimer ions are also observed by using SID on C18 and fluorinated hydrocarbon surfaces, with rate constants of 2 × 104 to 40 × 104 s−1. The SID activated monomer ions are assigned equivalent temperatures of 710–840 K by extrapolation of the thermal activation parameters. The protonated dimer ion (YGGFL)2 H+ decomposes thermally at 500–540 K to yield the monomer ion. The dimer also decomposes by SID at low collision energies 10–20 eV on both surfaces to yield the monomer ion, and at much higher energies of 60–80 eV to yield fragments identical to the decomposition of the monomer. The large energy requirement for fragmentation from the dimer is due to energy deposition into more degrees of freedom plus the additional energy required for dissociation of the dimer to the monomer. It is assumed that the energy deposition is linear with collision energy up to 80 eV, and that the energy becomes randomized throughout the dimer, including energy flow through the hydrogen bond(s). These mechanistic assumptions are supported quantitatively by the SID energy relations between monomer and dimer fragmentation. Thermal decomposition of the larger, multiply protonated melittin ion [M + 3H]3+ occurs at substantially higher temperatures, between 810–840 K, than those required for thermal decomposition of (YGGFL)H+, to yield many of the same sequence ions as produced by SID at 135 eV on a fluorinated surface.
Electron‐impact induced decomposition of some 3‐alkyl‐5‐substituted‐6‐methyl uracils
Authors: Jovanović Bratislav Ž. , Perić Aleksandra A. , Vajs Vlatka V. 
Published: May 2005

AbstractMass spectrometry was used to study the main fragmentation routes of some 3‐alkyl‐5‐substituted‐6‐methyl uracils. Differences in fragmentation were caused by changes in the structure of the alkyl group in position 3 of the uracil ring, with the same substituent in position 5, and by differences in the substituent in position 5.
The effect of the central linkage on the mass spectrometric behaviour of extended tetrathiafulvalenes
Authors: Orduna Jesús , Garín Javier , Frère Pierre , Nguyen Thi‐Thao , Gorgues Alain , Sánchez Luis , Martín Nazario , Seoane Carlos 
Published: May 2005

AbstractThe electron ionization‐induced fragmentation pattern of extended tetrathiafulvalenes has been studied by exact mass measurements, metastable ion analysis and collision‐induced dissociation mass spectrometry. The influence on the fragmentation of the central bridge linking the dithiole moieties is discussed.
Asparaginyl endopeptidase mapping of proteins with subsequent matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Kanda Fujihiro , Yoshida Seiichi , Okumura Tatsuya , Takamatsu Tasuku 
Published: May 2005

AbstractA matrix‐assisted laser desorption/ionization (MALDI) mass spectrometric mapping strategy for the identification and characterization of isolated and purified proteins is described. The method, which employs the combined usage of a new site‐specific enzyme Asparaginyl endopeptidase (Asn‐EP) for proteolysis, and MALDI for subsequent mass analysis, is capable of rapidly and sensitively examining the components of complex mixtures without any chromatographic or electrophoretic separation steps. Subpicomole sample quantities typically suffice to permit the confirmation of deduced primary structures and/or the identification of possible post‐translational modifications. The data obtained should also prove useful for mass matching and sequence homology searching of computerised protein sequence data bases of known proteins.
Synthesis and mass spectral fragmentation patterns of some new heterocyclic bis‐carboxamides
Authors: Karminski‐Zamola Grace , Crnjak Andrina , Bajić Miroslav 
Published: May 2005

AbstractThe electron impact mass spectra of some newly synthesized heteropolycyclic bis‐carboxamides are discussed. The dominant peaks in all these spectra are formed by the cleavage of the CN bond on one side of the anilino group with the formation of a fragment ion C9H4OSCI+ m/z 195, as the base peak. Cleavage of the CN bond with charge retention on nitrogen leads to characteristic ions in some cases.