bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical ionization mass spectra of linear alcohol polyethoxy carboxylates and polyethylene glycol dicarboxylates
Authors: Ding Wang‐Hsien , Fujita Yoshiko , Reinhard Martin 
Published: May 2005

AbstractThe chemical ionization (CI) mass spectra of propylated linear alcohol polyethoxy carboxylates (LAEC) and polyethylene glycol dicarboxylates (PEGDC) have been determined. Olefin displacement of the alkyl chain from the [M + H]+ ions of propylated LAEC formed the protonated polyethoxy carboxyl propyl ester, which then underwent a characteristic fragmentation by first losing water and then ethylene oxides. The fragmentation pattern for PEGDC [M + H]+ ions was similar to that of LAEC, except that the initial steps were displacement of one terminal propyl formate (HCOOC3H7) followed by a neutral loss of CH2O. Strong peaks due to protonated molecules were observed in both LAEC and PEGDC. Product‐ion mass spectra obtained from chemical ionization gas chromatographic/triple‐stage quadrupole mass spectrometric studies supported the proposed fragmentation mechanisms.
Matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry of DNA–Pt(II) complexes
Authors: Guittard J. , Pacifico C. , Blais J. C. , Bolbach G. , Chottard J. C. , Spassky A. 
Published: May 2005

AbstractMatrix‐assisted laser desorption ionization (MALDI) time‐of‐flight mass spectrometry has been used to characterize the reaction products of the 18‐mer deoxyribonucleotide d(AACGGTTAACCGTTAATT) with [Pt(NH3)3(H2O)]2+ and cis‐[Pt(NH3)2(H2O)2]2+. Characteristic peaks corresponding to different monofunctional adducts {18‐mer+n[Pt(NH3)3]} (n =1, 2, 3 and 4) have been observed with the triamino–monoaqua complex. With the diamino‐diaqua cis‐Pt complex, formation of a chelate {18‐mer+[Pt(NH3)2]} involving two adjacent guanines has been demonstrated. A good correlation between MALDI and polyacrylamide gel electrophoresis results is observed.
Electron ionization mass spectrometry of 2‐halo ethanols
Authors: Carbini Massimo , Napoli Massimo , Gambaretto Giampaolo , Traldi Pietro 
Published: May 2005

AbstractThe mass spectrometric behaviour of 2‐fluoro, 2‐chloro, 2‐bromo and 2‐iodo ethanols has been studied in detail with the aid of metastable ion studies and deuterium labelling experiments. Clear differences are observed and rationalized in terms both of carbon–halogen bond strengths and electronegativity.
Mass spectral study of some new arylsulphonylamido‐thiophosphonamides
Authors: Nicoara Simona , Culea Monica , Palibroda Nicolae , Cozar Onuc , Fenesan Ioan , Hantz Andrei 
Published: May 2005

AbstractThis paper presents the interpretation of the mass spectra of some N′,N′‐dimethylamido‐cyclohexylthio phosphonic derivatives of the corresponding p‐R substituted N‐methyl arylsulphonamides, under electron impact. Normal mass spectra at 70 eV, metastable transition detection and accurate mass measurements were used to elucidate the ion fragmentation pathways.
Fragmentation processes of 1,2‐diphenoxyethane and 2‐phenoxyethanol by electron impact
Authors: Sekiguchi Osamu , Ayuzawa Terukazu , Fujishige Masao , Yanagisawa Tamae , Tajima Susumu 
Published: May 2005

AbstractThe unimolecular fragmentation processes of 1,2‐diphenoxyethane (1) and 2‐phenoxyethanol (2) upon electron impact were investigated by a combination of mass‐analyzed ion kinetic energy (MIKE) spectrometry, deuterium‐labelling, high resolution mass spectrometry, and kinetic energy release (KER) measurement. The MIKE spectrum and the KER measurement indicate that the predominant fragment ion at m/z 120 was generated from metastable 1+· ions via loss of a phenol molecule (C6H6O, 7), and that it has the same structure as the molecular ion of 2,3‐dihydrobenzofuran (C8H8O, 3). The metastable 2+· ion eliminates C2H4O and C2H3O to produce product ions at m/z 94 (C6H6O+·, 7+·) and 95 (C6H7O+) with single and double hydrogen atom transfer, respectively. These reactions occur through some complex rearrangement reactions.
A new method for the rapid deconvolution of partially resolved spectra
Authors: Brenton A. Gareth , Lock Christopher M. 
Published: May 2005

AbstractA rapid and simple method for deconvolution of partially resolved spectra has been developed. The algorithm is simple, extremely fast, and capable of deconvolving whole spectra in real time on a fast personal computer. The technique has been evaluated using known test spectra whose resolution has been purposely degraded. The original spectra were reproduced accurately, both in the positions and the intensities of the individual peaks they contained. The method was initially developed for translational energy spectroscopy (TES), where there is little a priori information on the spacing and widths of individual peaks in a spectrum. Examples are given for actual experimental TES spectra of varying complexity and signal‐to‐noise ratios. Four key variables are required as input before the programme can be executed; these have been parameterized for a range of conditions and typical values have been established. The procedure may be well suited as a rapid pre‐screening process before more elaborate techniques are used and it can be applied widely, for example to deconvolute electrospray mass spectra.
A study of reduction phenomena in a high performance liquid chromatography/particle beam/mass spectrometer system
Authors: Xiao He , Brindle Ian D. , Jones Timothy R. B. , Miller Jack M. , Singh Raj P. 
Published: May 2005

AbstractIn this paper we report our studies of reduction phenomena in a high performance liquid chromatography/particle beam interface‐mass spectrometer system (HPLC/PB‐MS). It is shown that reduction takes place in the ion source of the mass spectrometer, but that the particle beam interface plays an important role in the reduction process since the HPLC mobile phase is involved in the reduction. HPLC flow rate and desolvation‐chamber temperature have significant effects on the reduction extent, while ion‐source temperature has only a minor effect. All the nitro compounds and sulfoxides tested in this work showed reduction in the system. There was no observed reduction for sulfones. 1,4‐Naphthaquinone showed significant reduction, while no reduction was observed for anthraqunone.
Non‐Equilibration of the [MH]− ions of isomeric dimethylsulphone and methyl methylsulphinate
Authors: Dua Suresh , Bowie John H. 
Published: May 2005

AbstractThe collision‐induced dissociations of −CH2S(O)2CH3, −CD2S(O)2CH3 and −CH2S(O)OCH3 indicate that (i) a sulphone/sulphinate ester rearrangement does not occur for these systems, (ii) proton transfer accompanying or preceding the fragmentation of the [M  H]− ion of the sulphone is a minor process, and (iii) the characteristic fragmentations of −CH2S(O)2CH3 and −CH2S(O)OCH3 form [CH2S(O)2]−. and HCSO− respectively.
Studies on non‐covalent associations of immunosuppressive drugs with serum albumin using pneumatically assisted electrospray ionization mass spectrometry
Authors: Bakhtiar Ray , Stearns Ralph A. 
Published: May 2005

AbstractPneumatically assisted electrospray ionization (ion‐spray) mass spectrometry was employed in the detection of non‐covalent interactions of immunosuppressive drugs with proteins. Non‐covalent complexes of albumin (rat and bovine) with FK506, dihydro‐FK506, and FK520 were observed. No complexation was detected between albumin and cyclosporin A (CsA), even at a protein‐ligand molar ratio of 1:20. It is suggested that the lack of detection of an albumin–CsA non‐covalent complex may be attributed to dissociation of the weakly associated species during ion vaporization. Nonetheless, preliminary results indicate that ion‐spray mass spectrometry has potential in qualitative evaluation of drug–plasma protein interaction.
Electron impact, metastable ion and CID spectra of some thieno[2,3‐d]‐1,3‐dithioles and thieno[3,4‐d]‐1,3‐dithioles
Authors: Rovira Concepció , Tarrés Judit , Dias Marylène , Garín Javier , Orduna Jesús 
Published: May 2005

AbstractThe mass spectra of 1,3‐dithiole‐2‐thione‐ and tetrathiafulvalene‐fused thiophenes have been studied. Isomer differentiation was achieved by electron impact, metastable ion and collision‐induced dissociation spectra.
Liquid chromatography/mass spectrometry with collision‐induced dissociation of arachidonic acid metabolites derivatized with aminobenzenesulphonic acid
Authors: Yang Y. , Griffiths W. J. , Lindgren J. Å. , Sjövall J. 
Published: May 2005

AbstractA fused‐silica capillary high‐performance liquid chromatography column (i.d. 0.25 mm) packed with octadecylsilane‐bonded silica has been used on‐line with continuous‐flow negative‐ion fast‐atom bombardment (FAB) mass spectrometry for the separation and structural analysis of series of fatty acids and arachidonic acid metabolites derivatized with 4‐aminobenzenesulphonic acid. Negative‐ion FAB spectra of the derivatized lipids showed strong [MH]− pseudomolecular ions. Collision‐induced dissociation of these anions produced structurally informative daughter ions, arising from charge‐remote fragmentations.
Detection of hydrogen‐bonded supramolecular complexes using electrospray ionization from chloroform
Authors: Cheng Xueheng , Gao Quanyin , Smith Richard D. , Simanek Eric E. , Mammen Mathai , Whitesides George M. 
Published: May 2005

AbstractThe stoichiometry of a noncovalent, hydrogen‐bonded supramolecular complex, hub(M)3·RCA3, was characterized using electrospray ionization from chloroform. The intact (1:3) complex was observed in the negative‐ion mode as a Cl−‐bound species using Ph4PCl as the source of the charge donor. Collisionally and thermally induced dissociation of the (1:3) complex resulted in the simultaneous loss of all the three RCA units, indicating a cooperative binding of RCA units in the (1:3) complex. These results suggest that the attachment of small, organic‐soluble ions may be a useful technique for mass spectrometric characterization of neutral supramolecular complexes that are stable or soluble only in non‐polar organic solvents.
Measurements of dication lifetimes by translational energy spectrometry
Authors: Safvan C. P. , Mathur D. 
Published: May 2005

AbstractA new application of mass spectrometry to experimental studies of molecular dynamics has been developed and implemented in which ion translational energy spectrometry at very high angular resolutions is utilized to study the unimolecular dissociation of metastable dications. A brief overview is presented of the experimental technique, which utilizes a ‘home‐made’, three‐sector (equivalent to BEE geometry) instrument. The fragmention kinetic energy spectrum obtained using such apparatus is capable of yielding information on the lifetimes of specific quantal states of dications of a wide variety of stable and radical species; two illustrative examples (CO2+ and SH2+) are presented.
Dissociative attachment studies by negative‐ion time‐of‐flight mass spectrometry
Authors: Krishnakumar E. , Nagesha K. 
Published: May 2005

AbstractExperiments using time‐of‐flight mass spectrometry for studying the formation of negative ions in dissociative attachment processes by electron impact are discussed. The problems of making accurate measurements of absolute partial cross‐sections have been solved using a combination of a new pulsed‐electron‐beam/pulsed‐ion‐extraction technique, the relative flow technique and a time‐of‐flight mass spectrometer. We also discuss some of the results obtained utilizing this method.
Dissociation dynamics of molecular ions in very high charge states
Authors: Mathur D. , Safvan C. P. , Krishnamurthy M. 
Published: May 2005

AbstractAn attempt is made to relate the dissociation dynamics of highly charged molecular ions (possessing charges in excess of 2+) to molecular structure. High‐level, ab initio configuration‐interaction calculations are carried out of the potential energy functions of N, for q = 2–12, and predictions are made of the values of the kinetic energies released upon unimolecular dissociation of such ions. The calculated values are found to be significantly lower than those expected from simple Coulombic considerations. Electron density distributions of highly charged molecules are calculated and, on the basis of these, a long‐lived state of a diatomic tri‐cation, CS3+, is predicted. Mass spectrometric evidence is produced which confirms these predictions.
Structural characterization of glutaminergic blocker spider toxins by high‐energy collision charge‐remote fragmentations
Authors: Fujita Tsuyoshi , Itagaki Yasuhiro , Naoki Hideo , Nakajima Terumi , Hagiwara Ken'ichi 
Published: May 2005

AbstractSpider venom gland stores various glutaminergic blockers such as acylpolyamines, besides proteins and peptides. A method is described for structure determination of these acylpolyamines using fast‐atom bombardment and four‐sector tandem mass spectrometry. The collision‐induced dissociation (CID) spectra of protonated molecular ions of synthetic model compounds show only a small number of weak, sequence‐related product ions. But, unlike the CID spectra of [M + H]+ ions, dissociation of sodium‐attached molecular ions leads to charge‐remote fragmentations and provides intense sequence‐related product ions.
Structure of the diene originating from a retro‐Diels–Alder cleavage, of the natural product kuwanon g
Authors: Takayama Mitsuo , Nomura Taro , Nojima Kazutetsu 
Published: May 2005

AbstractFragmentation of a natural Diels–Alder adduct, kuwanon G, has been examined using fast‐atom bombardment and collision‐induced dissociation (CID) techniques. The CID spectrum of a diene ion originating from a retro‐Diels–Alder cleavage of the [M + H]+ ion gave an intense peak arising from the fragmentation of the diene moiety, as well as characteristic peaks arising from the fragmentation of a tautomeric 2,2‐dimethylpyran ring structure. The results obtained suggest that the diene can be irreversibly converted into the 2,2‐dimethylpyran ring structure under gas‐phase mass spectrometric conditions.
Graphical method for artefact peak interpretation, and methods for their rejection, using double and triple sector magnetic mass spectrometers
Authors: Mouget Yves , Bertrand Michel J. 
Published: May 2005

AbstractThe problem of artefact peaks, in spectra obtained from various tandem mass spectrometric scans on instruments of both forward and reverse geometry, is examined. The filtering conditions imposed by additional analyzers are investigated, in order to evaluate the potential of several different triple sector geometries to reduce specific interferences. No previous evaluation of the rejection ability for artefacts of different origins has been presented with respect to the various geometries. In order to gain a better insight into the origin of various artefacts, and to more easily explain their occurrence in certain geometries, a new graphical representation was developed in order to take into account the effects of three analyzer fields. This approach allows different linked scans to be projected within a cube, while also qualitatively proposing an explanation for the presence or absence of artefact peaks. New scans can also be conceived by means of this method, as is the case with a new selected mass ion kinetic energy (SMIKE) scan, which allows artefacts present in MIKE scans performed using reverse geometry instruments to be determined.
Desorption of ions from locust tissues. III. Study of a metabolite of A‐destruxin using fast‐atom bombardment linked‐scan mass spectrometry
Authors: Loutelier Corinne , Marcual Albert , Lange Catherine , Cherton Jean‐Claude , Cassier Pierre 
Published: May 2005

AbstractThe process of the detoxification of A‐destruxin into a polar linear peptide in vivo in Locusta migratoria has been demonstrated using both high performance liquid chromatography and negative‐ion fast‐atom bombardment mass spectrometry. The final structure of the metabolite, after synthesis and comparison of retention time with the component in the crude biological mixture, was elucidated by positive‐ion fast‐atom bombardment linked‐scan mass spectrometry. Diagnostic fragment ions produced by collision‐induced dissociation are discussed.
Paclitaxel metabolites in human plasma and urine: Identification of 6α‐hydroxytaxol, 7‐epitaxol and taxol hydrolysis products using liquid chromatography/atmospheric‐pressure chemical ionization mass spectrometry
Authors: Royer I. , Alvinerie P. , Wright M. , Monsarrat B. , Ho L. K. , Armand J. P. 
Published: May 2005

AbstractReversed‐phase high‐performance liquid chromatography/mass spectrometry (LC/MS), with an atmospheric‐pressure chemical ionization (APCI) interface, has been applied to the identification of metabolites and derivatives of paclitaxel (taxol) in plasma and urine of patients treated with this new anticancer drug. Protonated molecules with substantial fragmentation were obtained using this ionization technique. The three ion series observed are characteristic of the intact molecule, the taxane ring, and the side chain at C13. Their analysis gives information about chemical modifications of the taxane structure at different positions of the molecule. Urine and plasma extracts were evaluated using the capacity to perform MS analysis directly on the entire effluent from conventional LC columns. Excellent spectra were obtained with 50 pmol of separated compounds in full scan mode. This technique allowed highly sensitive identification of 6α‐hydroxytaxol, the major human biliary metabolite, and of 7‐epitaxol in extracts of plasma and urine from patients. Taxol hydrolysis derivatives were observed for the first time in urine 24 hours after the end of the infusion period. Sensitivity could be increased further using single ion monitoring (SIM) mode, once a target derivative was identified. These results demonstrate that LC/MS with an APCI interface is useful for the characterization and pharmacokinetic analysis of taxoids in biological matrices.
Determination of isoflavones using high‐performance liquid chromatography with atmospheric‐pressure chemical ionization mass spectrometry
Authors: Aramendía Maria Angeles , García Isabel , Lafont Fernando , Marinas Jose María 
Published: May 2005

AbstractHigh‐performance liquid chromatography in combination with mass spectrometric detection (atmospheric‐pressure chemical ionization, APCI) was used to determine various isoflavones. Negative‐ion APCI ionization has proved to be a suitable technique for determining this class of natural compound, as it provides quality mass spectra which give not only the molecular weight of the isoflavones, but also their molecular structures; consistent collision‐induced dissociation pathways were elucidated and fragments are reported. Deuterium oxide was used to induce peak shifts in the mass spectra in order to determine the number of exchangeable hydrogen atoms in each molecule.
Collision‐induced fragmentation processes in some pesticides studied by tandem mass spectrometry
Authors: Yinon Jehuda 
Published: May 2005

AbstractTandem mass spectrometric (MS/MS) collision‐induced dissociation (CID) mass spectra of the molecular ion and main fragment ions in electron ionization of a series of pesticides were recorded using a triple quadrupole mass spectrometer. The fragmentation pathway map of simazine was deduced from the CID mass spectra. The utility of these CID fragmentation ions is demonstrated in the gas chromatography/MS/MS spectrum of carbofuran.
Fast‐atom bombardment mass spectra of the 132‐epimers of 132‐hydroxychlorophyll a
Authors: Kostiainen Risto , Hyvärinen Kristiina , Hynninen Paavo H. 
Published: May 2005

AbstractFast‐atom bombardment (FAB) mass spectra have been measured for resolved 132‐hydroxychlorophyll a epimers. The fragmentation of each epimer was studied by tandem mass spectrometry using linked scans at constant B/E. The FAB spectra showed a very intense radical cation (M+·) and EI‐type fragmentations. The most abundant fragment ions were formed by the losses of the phytyl, the 132‐hydroxy, and the 132‐methoxycarbonyl groups in various combinations. The fragment ions [M  OH]+, [M  phytadiene]+·, and [M  phytadiene  OH]+ were found to be characteristic of both 132‐hydroxychlorophyll a epimers. Nevertheless, it was shown that the loss of the 132‐hydroxy group occurs more easily from the 132(S)‐epimer than from the 132(R)‐epimer. This fragmentation difference offers a new possibility for the determination of the stereochemistry at the 132‐chiral centre of purified 132‐hydroxychlorophyll preparations.
Pyrolysis/gas chromatography/mass spectrometry of arsenic inorganic compounds
Authors: Chiavari Giuseppe , Fabbri Daniele , Galletti Guido C. 
Published: May 2005

AbstractPyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) of As4S6 (orpiment), As4S4 (realgar), As4O6 (arsenolite), NaH2AsO4 (sodium di‐H‐orthoarsenate) was performed using a platinum‐filament pyrolyzer heated at 700°C for 10 s and coupled to a capillary gas chromatograph/ion trap mass spectrometer. As4 was observed as a pyrolysis fragment in the pyrograms of all compounds. Pyrolysis of NaH2AsO4 equivalent to 100 ng of As, produced a strong As4 chromatographic peak. As4S3 and As4S4 were detected as pyrolysis products of As4S6 (orpiment). As4S4 (realgar) and As4O6 (arsenolite) were detected as intact molecules after pyrolysis. By contrast, intact As4S6 was not detected after pyrolyses in the range 400–700°C. As4 was detected as an impurity in the painting layer of an Egyptian mummy. The mass spectra of such arsenic compounds, none of which is included in the NIST library of spectra, are reported. Advantages and limitations of PY/GC/MS as a technique for the qualitative detection of arsenic inorganic compounds are discussed.
Mass spectrometry of lepidopterous insect sex pheromones containing a diene system
Authors: Yuan Gu , He Meiyu , He Xioran 
Published: May 2005

AbstractThe mass spectrometric behavior of some diene‐based sex pheromones of lepidopterous insects, under electron impact ionization conditions, was studied with the aid of mass‐analyzed ion kinetic energy spectroscopy and high‐resolution data. The similarity of the mass spectra of these dienes and their ability to distinguish double bond positional isomers and geometrical isomers was examined by a ‘minimum‐maximum’ similarity analysis.
Mass spectrometry of cyanocobalamine, glucose and raffinose in the solid state and on a disperse oxide surface
Authors: Pokrovskiy V. A. , Galagan N. P. , Dembnovetskaya L. I. 
Published: May 2005

AbstractThe biologically active systems were synthesized by adsorption of vitamin B12, glucose and raffinose on an ultrafine oxide surface and studied by means of thermal analysis and temperature‐programmed mass spectrometry. It is shown that adsorption of cyanocobalamine (B12) on the silica surface transformed the propionamide group to a weakly bound form. The role of the charged cobalt atom and of the propionamide and benzimide groups in the adsorption mechanism is discussed. Experimental data were obtained confirming the stable adsorption of glucose and raffinose on an ultrafine pyrogenic silica surface modified by amino groups.
Temperature‐programmed mass spectrometry of biomolecules in surface chemistry studies
Authors: Pokrovskiy V. A. 
Published: May 2005

AbstractThe peculiarities of the temperature‐programmed mass spectrometry (TPDMS) experimental technique are discussed with reference to studies of biologically active molecules absorbed on ultrafine oxide surfaces. Simple theoretical models are presented in order to allow an approximate analytical treatment of TPDMS data.