bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of impurities in a synthetic renin substrate peptide by fast‐atom bombardment mass spectrometry and hybrid tandem mass spectrometry
Authors: Mathews W. Rodney , Runge Thomas A. , Haroldsen Peter E. , Gaskell Simon J. , Tomer K. B. 
Published: May 2005

AbstractFast‐atom bombardment mass spectrometry of a synthetic renin substrate decapeptide (Pro‐His‐Pro‐Phe‐His‐Leu‐Val‐Ile‐His‐D‐Lys) indicated the presence of several of side‐products, including a component 12 Da higher in mass. Low‐energy collisionally activated decomposition analyses were performed using a hybrid tanden, instrument and demonstrated that the heavier side product had two components, in which the structural modification was either at the N‐ or the C‐terminus. Additional analyses of the N‐acetyl derivative indicated that for each component the strucutrual modification blcoked a site of N‐acetylation. It is suggested that the formation of these side products is attributable to the generation of formaldehyde, during removal of the histidine protecting group (benzyloxymethyl), which reacts with the N‐terminus of the peptide to give an imidazolidinone structure or with the D‐lysine ε‐amine group to yield an imine. While the precise genesis of the side‐products remains speculative, it is clear that the combined strategy of derivatization and tandem mass spectrometry has allowed structural conclusions concerning individual components of an isobaric mixture.
Ion chemistry of the methylcarbonate anion
Authors: Hayes Roger N. , Waugh Russell J. , Bowie John H. 
Published: May 2005

AbstractThe ion MeOCO fragments upon collisional activation by competitive losses of Me, CH2 and CO2. The loss of formaldehyde involves hydride‐ion transfer to form HCO. MeOCO reacts as a methoxyl‐ion donor in a characteristic reaction with sulphur dioxide, i.e. MeOCO + SO2→ MeOSO+ CO2.
Rapid analysis of a peptide by fast‐atom bombardment mass spectrometry after polyacrylamide gel electrophoresis
Authors: Camilleri P. , Haskins N. J. , Hill A. J. 
Published: May 2005

AbstractGel electrophoresis has been a powerful technique for the separation of peptides and proteins for many years. After electrophoresis separation on a polyacrylamide gel, the peptide bradykinin was localized using Coomassie Blue as a staining dye. Excess dye was removed by washing the gel with water, For mass spectrometric analysis, bands containing the peptide were crushed, extracted with acetic acid and the eluent applied to the fast‐atom bombardment probe. Under these conditions the protonated molecule of bradykinin was clearly observed. Also apparent were sequence ions at about the same intensity observed from authentic bradykinin.
Pulsed extraction field for neutralization of sample charging in secondary‐ion mass spectrometry
Authors: Appelhans A. D. , Dahl D. A. , Delmore J. E. 
Published: May 2005

AbstractA new technique for inhibiting the build‐up of surface charge on electrically non‐conducting samples in secondary‐ion mass spectrometry (SIMS) when using a negative‐ion or neutral primary beam is described. The technique, which involves alternately extracting positive and negative particles from the sample by rapidly reversing the polarity of the secondary‐ion extraction voltage, is non‐intrusive and applicable to all materials. A static SIMS instrument utilizing a negative‐ion and neutral molecular primary beam has been modified to demonstrate the technique.
Application of liquid chromatography/thermospray mass spectrometry to studies on the formation of glutathione and cysteine conjugates from monomethylcarbamate metabolites of bambuterol
Authors: Rashed Mohamed S. , Pearson Paul G. , Han Deog‐Hwa , Baillie Thomas A. 
Published: May 2005

AbstractLiquid chromatography/thermospray mass spectrometry (LC/TSP‐MS) has been used to identify and study the rates of formation of S‐(N‐methylcarbamoyl) cysteine and S‐(N‐methylcarbamoyl)glutathione as products of the in vitro reaction of cysteine and glutathione, respectively, with two monomethylcarbamate metabolites of the bronchodilator pro‐drug bambuterol. The conjugates of interest afforded MH+ species and yielded abundant structurally informative fragment ions which were employed in the development of quantitative, selected‐ion monitoring assays. It is concluded that LC/TSP‐MS represents a rapid and convenient approach to the direct aqueous‐phase analysis of the class of S‐(N‐alkylcarbamoyl) conjugates of cysteine and glutathione.
Low‐energy collisional activation spectra of – O‐ and N‐epoxypropyltrahydroacridines
Authors: Madhusudanan K. P. , Asthana Pratibha , Rastogi Shri Nivas 
Published: May 2005

AbstractA study of the low‐energy collisional activation (CA) spectra of O‐ and N‐epoxypropyltetrahydroacridines has revealed that the two isomers show characteristic differences in their spectra. The CA spectra of the M+ [MH], MH+ [M + C2H5]+ and [M + C3H5]+ ions are discussed.
Charge‐inversion reactions of CF+ and CCI+ ions
Authors: Griffiths W. J. , Harris F. M. , Barton J. D. 
Published: May 2005

AbstractDouble‐charge‐transfer spectroscopy has been used to confirm that CF+ and CCI+ can exist for times greater than several μs in electronically excited states. From the spectra obtained it was shown that those states are 4.7 ± 0.7eV and 3.3 ± 0.5eV above the ground states for CF+ and CCI+, respectively. The experimental technique is quite sensitive to the detection of long‐lived excited states and it is shown for CCI+ that the relative populations of the excited and ground states are markedly different when CFCI3 and CF2ClCFCI2 are used as the precursor molecules in the dissociative‐ionization process.
The effect of surface activity on quantification of linear alkylbenzenesulfonates by fast‐atom bombardment mass spectrometry
Authors: Wernery J. David , Peake David A. 
Published: May 2005

AbstractThe effect of surface activity differences of sodium alkybenzene sulfonate homologs on quantification by fast‐atom bombardment mass spectrometry is investigated. By using three stable‐isotope internal standards to bracket the chainlength distribution, accurate quantification of surfactant mixtures is achieved. With a single deuterated internal standard, skewing of the distribution occurs. The magnitude of the skewing depends on the concentration of the sample and signal‐averaging time. The use of model mixtures of pure surfactants and analysis of commercial surfactant mixtures is demonstrated.
Preliminary studies on ion chromatography/fast‐atom bombardment mass spectrometry for the characterization of various ionic compounds
Authors: Al‐Omair Ali S. , Todd John F. J. 
Published: May 2005

AbstractAn ion chromatography/mass spectrometry system which makes use of a continuous‐flow fast‐atom bombardment probe, has been constructed and evaluated. Examples are given of applications to the analysis of inorganic anions (ion‐exchange chromatography), water soluble vitamins (ion‐pair chromatography) and glucose derivatives (ion‐excluson chromatography).
A deceleration lens system for hybrid mass spectrometers
Authors: Suter M. J.‐F. , Stepnowski R. M. , Schlunegger U. P. 
Published: May 2005

AbstractA simple and efficient deceleration system for the coupling of magnetic and electric sector instruments to quadrupole analyzers is described. The trasnsmission efficiency of the system appears to be at least 80% or better as the ions are decelerated from 3 ke V to 30 eV (a deceleration factor of 1:100). No mass discrimination was observed in the range up to mass 1000.
Retro Diels‐Alder rearrangement in 4‐hydroxy‐2‐acylcyclohexane‐1,3‐diones
Authors: Mudd A. 
Published: May 2005

AbstractHigh mass ions at even m/z values in the spectra of 4‐hydroxy‐2‐acylcyclohexane‐1,3‐diones are due to retro Diels‐Alder rearrangement. Evidence for the position of the enolic double bond in unsymmetrical 2‐acylcyclohexane‐1,3‐diones is adduced.
On‐line liquid chromatography/fast‐atom bombardment of protein tryptic digests
Authors: Bell David J , Brightwell Malcolm D. , Neville William A. , West Andrew 
Published: May 2005

AbstractThe assignment of the peptides in the chromatographic separation of tryptic peptides from a large protein was investigated by liquid chromatography/fast‐atom bombardment mass spectrometry (LC/FABMS). Methodical interfacing of the instrumentation was required to maintain the resolution of the 70 peptides in the mixture whilst gaining maximum fast‐atom bombardment sensitivity. The reconstructed ion current showed excellent correlation with ultra violet detection, illustrating that chromatographic resolution was indeed preserved. Results allowed the determination of retention times of peptides by plotting the mass chromatograms of the expected materials from the acquired spectra. It was also found that spectrum‐averaging and background subtraction could yield considerable sequence information from the LC/FAB spectra of peptides, acquired using a two‐sector instrument.
Characterization of isomeric pyranocoumarins by collision‐induced tandem mass spectrometry
Authors: Kiremire B. T. , Chiarello D. , Traldi P. , Vettori U. , Guiotto A. , Rodighiero P. 
Published: May 2005

AbstractThree variously annulated isomeric pyranocoumarins 1, 2 and 3 have been examined using electron ionization and collisional mass spectroscopy. All the spectra showed diagnostic fragments that allowed characterization of the isomers. The best results were obtained using daughter‐ion spectra of selected parent ions.
Secondary‐ion mass spectrometry of particle beams
Authors: Sanders Phillip E. 
Published: May 2005

AbstractA particle beam liquid chromatography/mass spectrometry interface has been developed which interfaces to a liquid secondary‐ion mass spectrometry ion source. High flow rates (e.g., 0.5–2.0 mL/min) have been achieved with sensitive performance. Matrix compounds were added through the particle‐beam interface. A cesium ion gun is used as the source of the primary ions.
Unimolecular chemistry of the 4‐hexen‐3‐one radical cation
Authors: Bouchoux G. , Djazi F. , Jaudon P. , Lefevre O. 
Published: May 2005

AbstractIonized 4‐hexen‐3‐one, fragments by losing CH˙3, CO, C2H4 and C2H˙5. The former process, which is found to dominate dissociations of metastable molecular ions proceeds via the cyclized enol cation CH3ĊHCH2CH2C(OH) = CH+. Use of deuterium labelling and relevant thermochemical data allow the determination of the various reaction mechanisms.
The use of 2‐hydroxyethyl disulphide as a matrix in liquid secondary‐ion mass spectrometry
Authors: Kenny Peter T. M. 
Published: May 2005

AbstractSeveral novel applications of 2‐hydroxyethyl disulphide as a matrix material in liquid secondary‐ion mass spectrometry are presented. This matrix is superior to the conventional glycerol matrix for the analysis of peptides with hydrophobic residues. It was found to be an excellent matrix for the analysis of a wide range of other compounds. It is chemically inert, enhances the formation of [M + Na]+ and [M + K]+ adducts and gives few ions above m/z 300.
Computer‐aided interpretation of mass spectra by a combination of library search with principal component analysis
Authors: Varmuza K. , Werther W. , Henneberg D. , Weimann B. 
Published: May 2005

AbstractThe mass spectral set comprising the “hitlist” of a library search for spectra similar to that of an unknown is investigated by exploratory data analysis. Principal‐component mapping is used to present the “hitlist” as a two‐dimensional plot which allows an interactive classification of the unknown and the recognition of erroneous library spectra.
The loss of amine from low internal energy ions of aminosteroid stereoisomers
Authors: Mollova Nevena , Longevialle Pierre , Bouchoux Guy 
Published: May 2005

AbstractD‐labelling experiments show that the extent of hydrogen‐atom exchanges accompanying the loss of amine from ionized aminosteroids of low internal energy depends on structure and also, in a few cases, on the configuration of the amine function. Mechanisms are proposed.
Identification of 2‐(2′‐octenyl) succinic acid in urine
Authors: Giordano Giuseppe , McMurray Walter J. , Previs Stephen F. , Welch Roy D. , Rinaldo Piero 
Published: May 2005

Abstract2‐(2′‐octenyl)succinic acid has been identified in urine samples from children investigated for a possible inherited metabolic disease. Its structural identification has been achieved by gas chromatography/mass spectrometry using both electron ionization and chemical ionization and by tandem mass spectrometry (MS/MS) using fast‐atom bombardment and high‐resolution electron‐ionization analyses of the molecular ion in a complex biological matrix. The localization of the double bond was obtained by interpretation of a unexpected rearrangement reaction occurring after dimethyl disulfide derivatization.
Sequence‐informative fragmentation of peptides up to a molecular weight of 4.6 kDa in plasma‐desorption mass spectrometry
Authors: Vorst H. J. , van Tilborg M. W. E. M. , van Veelen P. A. , Tjaden U. R. , van der Greef J. 
Published: May 2005

AbstractThe potential of plasma‐desorption mass spectrometry (PDMS) in peptide sequencing is investigated. This paper shows that PDMS spectra recorded for longer times and using larger amounts of peptide than used for obtaining molecular weight information, provides sequence information on peptides of up to 4.5 kDa molecular weight. This approach strongly enhances the utility of PDMS for validation of the sequence of recombinant peptides.
Observation of isolated electronic states in the collision‐induced dissociation of nitromethane ions
Authors: Qian Kuangnan , Shukla Anil , Futrell Jean 
Published: May 2005

AbstractCollision‐induced dissociation of nitromethane molecular ions to NO+ and NO has been studied at 19 eV center‐of‐mass collision energy using a crossed‐beam tandem mass spectrometer. Center‐of‐mass velocity contour maps for the two dissociation processes are distinctly different; NO has its intensity maximum at 7 degrees with energy transfer endothermicities of 1.8 eV while NO+ has intensity maxima at zero and 8 degrees with energy transfer endothermicities of 0.3 and 5.5 eV, respectively. The observation of two distinct peaks in the NO+ contour map clearly demonstrates that nitromethane ions excited to 5.5 eV internal energy do not dissociate from the ground state potential surface. Dissociation is faster than intramolecular relaxation, in contradiction to the fundamental postulate of statistical theories (RRKM, QET) for unimolecular dissociation.
Evidence for distinction of cis and trans isomers of mono‐unsaturated fatty acids by fast‐atom bombardment tandem mass spectrometric analysis
Authors: Jensen Nancy , Lam Kai , Cody Robert B. , Tamura Jun 
Published: May 2005

AbstractFast‐atom bombardment tandem mass spectrometry negative‐ion analysis of the [MH]− ions of the cis and trans isomer pairs of 9‐hexadecenoic and 9‐octadecenoic acid with a four sector mass spectrometer, reveals distinctions between the cis and trans isomers of each pair. The definitive fragmentation is at the bond allylic to the double bond in the distal position on the chain. Fragmentation at this site involves both remote‐charge‐site fragmentation and a cleavage fragmentation.
Matrix‐assisted laser desorption of peptides in transmission geometry
Authors: Vertes Akos , Balazs Laszlo , Gijbels Renaat 
Published: May 2005

AbstractThe possibility of performing matrix‐assisted laser desorption experiments in transmission geometry is demonstrated for two neuropeptides (substance P and bombesin), for six analogs of the melanocyte‐stimulating hormone (MSH) core and for coliagenase enzyme substrates. Positive‐ and negative‐ion spectra of several peptides are produced without the presence of a metallic substrate. Cationized quasi‐molecular ions are abundant in the positive spectra. Peak broadening in the high‐mass range can be the consequence of overlapping molecular and adduct ions. The presence of synthesis by‐products can be identified readily from the spectra. Ultimately, picogram detection limits are possible for important bioactive peptides and other large molecules. Because of the clearly demonstrated matrix‐assisted laser ionization in a homogeneous environment, metal substrate participation in the volatilization mechanism seems less likely.
Molecular weight determination of proteins from multiply charged ions using thermospray ionization mass spectrometry
Authors: Straub Kenneth , Chan Kelvin 
Published: May 2005

AbstractData are presented showing the use of thermospray ionization to generate multiply charged ions for a number of proteins over the molecular weight range 5000–30000. These measurements were carried out on an unmodified, commercially available thermospray ion source. Between +3 and +19 charges were observed for a series of model proteins. Data can be obtained on as little as 100 pmol of sample. The accuracy and precision of the molecular weight determinations for these proteins is similar to those previously reported for these samples using electrospray or ionspray ionization. The formation of multiply charged ions from proteins via thermospray ionization occurs over a wide range of aqueous/organic solvent compositions, facilitating its interfacing with high‐performance liquid chromatography using conventional diameter columns.
Matrix‐assisted infrared‐laser (2.94 μm) desorption/ionization mass spectrometry of large biomolecules
Authors: Overberg A. , Karas M. , Bahr U. , Kaufmann R. , Hillenkamp F. 
Published: May 2005

AbstractThe matrix‐assisted desorption/ionization of large biomolecules with a wavelength of 2.94 μm in the infrared is reported. A mechanically Q‐switched Erbium‐YAG laser with a pulse width of ca. 200 ns was used for the experiments. A large variety of matrices have been used successfully, among them all matrices found useful for ultraviolet desorption and, in addition, carboxylic acids, glycerol and urea. Desorption of molecules at this wavelength and caffeic acid as a matrix results in ions with up to 13 charges per ion.
Accurate ion abundance measurements in ion cyclotron resonance mass spectrometry by linear prediction
Authors: Loo J. F. , Krahling M. D. , Farrar T. C. 
Published: May 2005

AbstractIn standard pulsed ion cyclotron resonance mass spectrometry (ICRMS) mass spectra are generated by converting the time domain signal to the frequency or mass domain by fast Fourier transform (FFT). The FFT requires long acquisition times to acquire high resolution mass spectra. In ICRMS, long acquisition times introduce distortions in the peak intensities of the transformed spectrum that lead to errors in ion abundance. We report here the use of linear prediction methods on data sets collected during much shorter acquisition times to determine actual ion abundances more accurately.
The detection of large molecules in matrix‐assisted UV‐laser desorption
Authors: Spengler Bernhard , Kirsch Dieter , Kaufmann Raimund , Karas Michael , Hillenkamp Franz , Giessmann Ulrich 
Published: May 2005

AbstractMechanisms related to high‐mass ion detection were studied using matrix‐assisted UV laser desorption for ion generation and a tandem (MS/MS) time‐of‐flight mass spectrometer for the analysis of secondary species formed at the conversion dynodes. Secondary‐electron emission was found to be less pronounced with increasing molecular weight. Instead small secondary ions generated by collision of primary ions with the conversion dynodes appeared to be the dominant process for the detection of ions of masses up to several hundred thousand Da. The use of microchannel plate detectors has been shown to become less effective for high molecular weight applications. Mass spectra of secondary ions emitted from a conversion dynode bombarded with keV primary ions have been recorded. Regardless of the composition of the primary molecules, the secondary mass spectra were similar. Sputtering of surface adsorbates is assumed to be the major mechanism of secondary ion formation, rather than surface induced dissociation or fragmentation of the primary ions.
Ion‐trap mass spectrometry in ion structure studies. 1. Characterization of isomeric hydroxyindoles by electron ionization and energy‐resolved collision‐activated mass spectrometry
Authors: Evans Catherine , Catinella Silvia , Traldi Pietro , Vettori Umberto , Allegri Graziella 
Published: May 2005

AbstractThree hydroxyindole isomers were investigated by conventional electron ionization (EI) mass spectrometry and by collision‐activation (CA) experiments. Although the EI mass spectra of the three isomers are virtually superimposable, 3‐hydroxyindole can easily be differentiated from the others by single‐energy collision spectroscopy. Only by energy‐resolved mass spectrometry (ERMS) could the characterization of the 4‐ and 5‐ hydroxyindole isomers be achieved. ERMS, which in the ion‐trap mass spectrometer can be performed by different methods, was achieved by changing both the AC supplementary voltage and the βz value at which the collision experiments were performed. The first method proved to be the most effective in the present case. Further collision experiments, carried out at a range of AC voltage durations did not yield energy‐resolved data.
The characterization of polystyrene oligomers by field‐desorption mass spectrometry
Authors: Rollins K. , Scrivens J. H. , Taylor M. J. , Major H. 
Published: May 2005

AbstractField‐desorption mass spectrometry has been used to characterize polystyrene oligomers of molecular weight up to 15 000 Da. The technique shows good agreement with molecular weight data calculated using vapour‐phase osmometry and gel‐permeation chromatography but in addition provides much more detailed information in terms of oligomer distribution and the nature of end groups present in the oligomers.
A detailed study of the characteristics of the ion‐trap mass spectrometer using dynamically programmed scans
Authors: Penman A. D. , Todd J. F. J. , Thorner D. A. , Smith R. D. 
Published: May 2005

AbstractThe aims of the investigation were to use the method of dynamically programmed scans to study in detail some tandem mass spectrometric characteristics of the ion‐trap mass spectrometer and then to use the programs to investigate the possibility of performing benchtop gas chromatography/tandem mass spectrometry experiments on the standard instrument. In particular we have examined the effect of applying a DC ramp during the ‘tickle’ period as a means of broadening the range of resonant frequencies, thereby facilitating the tuning required to effect excitation.
Fast‐atom bombardment mass spectrometry and fast‐atom bombardment tandem mass spectrometry of some monosaccharide oximes
Authors: New A. P. , Haskins N. J. , Lee B. 
Published: May 2005

AbstractThe oximes of monosaccharides have not been well characterized by mass spectrometry. Conventional electron ionization (EI) experiments have supported the structures of these compounds but the data produced are usually equivocal (Finch and Merchant, JCS Perkin 1, 1682 (1975)). The application of fast‐atom bombardment mass spectrometry to monosaccharide oximes gives molecular weight information. However, little fragmentation is observed and it is not possible to distinguish between stereoisomers. Using fast‐atom bombardment tandem mass spectrometry experiments, we have produced daughter‐ion spectra which are sufficiently different to enable us to distinguish between the stereoisomers of the oximes of monosaccharides.