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  • Artikel  (523)
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  • 1
    Digitale Medien
    Digitale Medien
    An investigation into the electron-ionization-induced mass spectrometric behaviour of some trans- and cis-substituted cycloalkylamines of pharmaceutical interest (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1-5 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The electron-ionization-induced mass spectrometric behaviour of eight cyclopentylamine and cyclohexylamine derivatives, recently synthesized, has been investigated by means of accurate mass measurements and metastable ion studies. These approaches allowed an easy structural characterization of the title compounds. In particular, mass-analyzed ion kinetic energy spectroscopy proved effective for the differentiation of cis- vs trans-isomers.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070102
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  • 2
    Digitale Medien
    Digitale Medien
    Matrix-assisted laser desorption of peptides and proteins using a quadrupole ion trap mass spectrometer (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 27-32 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The analytical capabilities of the combination of matrix-assisted laser desorption with a quadrupole ion trap utilizing ion injection are demonstrated using peptides and proteins with molecular weights up to 43 kDa.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070107
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  • 3
    Digitale Medien
    Digitale Medien
    Thermal surface ionization of quaternary ammonium salts in particle-beam mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 37-40 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The applicability of thermal surface ionization in liquid chromatography/particle-beam mass spectrometry is investigated for the analysis of quaternary ammonium compounds. The compounds are mass anlyzed in a filament-off mode of operation with a particle-beam interface. An intense signal of the molecular cations is observed, while fragmentation can be induced by gas collisions and characterized using tandem mass spectrometry. A significant gain in signal-to-noise ratio in thermal surface ionization relative to electron ionization is observed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070109
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  • 4
    Digitale Medien
    Digitale Medien
    Cyclic boronates in the mass spectrometry of ecdysteroids (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 46-52 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: For the structural elucidation of ecdysteroids a reaction with phenylboronic acid has been employed. This reaction takes place exclusively on the C20,C22 diol moiety, thus facilitating fast and easy detection of this moiety in the molecule od ecdysteroid. This derivatization also redirects fragmentation to C17/C20 bond cleavage with charge retention on both fragments enabling assessment of the structure both of the steroid nucleus and of the side-chain. Possible reaction of phenylboronic acid with the diol moiety of the glycosyl group of the glycoside od ecdysteroid, producing di-adduct, is demonstrated; participation of the 5β-hydroxy group of 5β,20-dihydroxyecdysone in the formation of such a di-adduct is discussed; and the role of theenol form of the 6-carbonyl group is proved.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070112
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  • 5
    Digitale Medien
    Digitale Medien
    The use of hydrogen-deuterium exchange to facilitate peptide sequencing by electrospray tandem mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 58-62 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The utility of hydrogen-deuterium exchange for sequencing peptides by mass spectrometry is demonstrated. The number of exchangeable hydrogens in a peptide is readily obtained by electrospray analysis of the peptide dissolved in deuterated solvents. This information can be used, in conjunction with published computer algorithms for interpreting peptide mass spectra, to reduce significantly the number of candidate sequences that fit the experimentsl data. This information, when combined with fragment-ion information in the mass spectrum, greatly increases the reliability of sequence determination.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070114
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  • 6
    Digitale Medien
    Digitale Medien
    Stereospecific Retro-Diels-Alder reactions in the negative-ion mass spectra of Diels-Alder adducts of substituted p-benzoquinones and glucofuranodienesCDRI Communication. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 92-94 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The negative ions of cis- and trans-Diels-Alder adducts of p-benzoquinones and glucofuranodienes enable these stereoisomers to be differentiated because the cis- isomers undergo a highly-favoured retro-Diels-Alder reaction.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070119
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  • 7
    Digitale Medien
    Digitale Medien
    Erratum (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 109-109 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070124
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  • 8
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993) 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070201
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  • 9
    Digitale Medien
    Digitale Medien
    Vaporization processes of borosilicate coatings studied by high temperature mass spectrometry and using an induction plasma generator (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 127-131 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A new approach has been applied to study processes which take place during the thermochemical action of air (or other) plasma on heat protection materials. Vaporization processes of the borosilicate coating of ‘Buran's’ heatprotective tiles, both the initial state and after rf-entry simulation testing (up to 100 landings), were investigated by the Knudsen mass spectrometric effusion method. Modelling of the thermochemical action of the shock-layer plasma onto the front surfaces of real-scale tiles was carried out by using an induction plasma genetor of 500kW power. It was established that the thermochemical action of the plasma causes, essentially, a decrease of vapour pressure over the coating. However, despite this decrease, the pressures observed are significantly higher than those over the SiO2-B2O3 system at the same temperature, due to gas-phase SiO production by reaction between boron and silicon oxides and SiB4, which are contanied in the coating. The data available aiiow one to postulate the presence of the SiBO molecule in the gas phase. Data on mass-loss rates obtained by direct measurments after re-entry simulation compared nwell with the values calcuted from mass spectrometric data. It is suggested that the difference observed is caused by thermochemical action of atomic oxygen on the coating.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070203
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  • 10
    Digitale Medien
    Digitale Medien
    Differentiation of anomeric glycosyl azides using mass spectrometric methods (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 147-151 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Electron ionization (EI), chemical ionization and mass-analysed ion kinetic energy (MIKE) spectra have been applied with the aim of obtaining an unambiguous differentiation between the anomeric 2,3-O-isopropylidene α-and β-D-ribofuranosyl azide derivatives. The MIKE spectra of their metastable [M — CH3]+ ions, originating from EI, showed a decomposition pattern allowing distinction between the anomers. The origin of the ions in the EI mass spectra, supported by examination of the deuterium-labelled derivatives, makes it possible to identify the actual azido group orientation in a particular anomer.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070207
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  • 11
    Digitale Medien
    Digitale Medien
    Randomization in the fragmentation of benzophenone (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 163-166 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The hydrogen and carbon randomization in the mass spectrometric behaviour of benzophenone has been studied by deuterium and 13C-labelling. Hydrogen scrambling is involved only in the reactions of primary loss of hydrogen from molecular ions, as well as in secondary elimination of two hydrogen atoms from [M—CO]+· ions. The carbon randomization does not feature in benzophenone upon electron impact.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070210
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  • 12
    Digitale Medien
    Digitale Medien
    Liquid chromatography/mass spectrometry analysis of an enkephalin mixture using an autospec dynamic liquid secondary-ion mass spectrometer interface (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 176-178 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A mixture of four enkephalins was separated by reverse-phase high-performance liquid chromatography combined with dynamic liquid secondary-ion mass spectrometry. A newly developed screen/wick target made the method sensitive and reproducible.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070213
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  • 13
    Digitale Medien
    Digitale Medien
    Influence of acetylation on the [M + Na]+ ion formation of simple phenol and aniline compounds under fast-atom bombardment conditions (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 172-175 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The influence of acetylation on the formation of sodium adduct [M + Na]+ ions, under fast-atom bombardment conditions, has been investigated using monosubstituted phenol and aniline compounds. The acetylation of o-isomers, except for the nitrophenols, highly enhanced the [M + Na]+ ion formation, while m- and p-isomers showed little effect on acetylation except for p-methoxyphenol and aniline. The favorable effect of acetylation on [M + Na]+ ion formation is explained by the conformational flexibility of C—O—Ac and G—NH—Ac functions and the carbonyl oxygen as a cation-accepting site, which are advantageous for the multisite interaction with a Na+ ion.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070212
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  • 14
    Digitale Medien
    Digitale Medien
    Laser mass spectrometry of dibenzodioxin, dibenzofuran and two isomers of dichlorodibenzodioxins: Selective ionization (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 183-185 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Laser-induced mass spectra and UV spectra of dibenzodioxin, dibenzofuran, and two isomers of dichlorodibenzodioxin measured by means of resonance-enhanced multiphoton ionization in a supersonic molecular beam are presented. The UV spectra show sharp bands and large wavelength shifts both being specific to the number and position of the chlorine atoms. The mass spectra are free of fragments. Therefore the prerequisites for isomer selective ionization and detection of these substances are fulfilled. This encourages further work on polychlorinated dibenzodioxins and dibenzofurans.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070303
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  • 15
    Digitale Medien
    Digitale Medien
    Observation of intact (heme-bound) myoglobin by electrospray ionization on a double-focusing mass spectrometer (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 186-189 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A noncovalently bound complex, the heme-apomyoglobin protein system (Mr 17 568), was detected using electrospray ionization on a double-focusing mass spectrometer with an array detector. The kilovolt energy conditions used for ion transmission and focusing did not cause significant amounts of fragmentation of the weakly-bound complex. With a high-performance array detector, femtomolar sensitivity was achieved for myoglobin in water.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070304
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  • 16
    Digitale Medien
    Digitale Medien
    Determination of sulfated peptides via prompt fragmentation by UV matrix-assisted laser desorption/ionization mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 201-204 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Determination of sulfation on peptides is difficult by biochemical methods if only a few picomoles of sample are available. By varying the laser irradiance, matrix-assisted laser desorpiion/ionization mass spectra were obtained containing fragment ions diagnostic of sulfation.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070307
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  • 17
    Digitale Medien
    Digitale Medien
    A model for peak shape in slow-scan-rate quadrupole ion trap mass spectronnetry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 210-214 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The results of calculations are presented that address the effect of the scan rate on peak shape and position for slow-scan-irate detection in the quedrupole ion trap. The calculations are based on a model for signal detection that account for the change in the number of ions in the trap as the ejection field sweeps across a peak. The calculations predict that reduced scan rates lead to peak narrowing, peak asymmetry, and a shift in the apparent mass in the in resulting mass spectrum.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070309
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  • 18
    Digitale Medien
    Digitale Medien
    In situ reduction suitable for matrix-assisted laser desorption/ionization and liquid secondary ionization using tris(2-carboxyethyl)phosphine (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 225-228 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The suitability of the hydrochloride salt of tris(2-carboxyethyl)phosphine (TCEP) for in situ reduction with matrix-assisted laser desorption/ionization (MALDI) and liquid secondary ionization (LSI) mass spectrometry is evaluated. TCEP can be used to irreversibly reduce organic disulfldes to thiols in water and is active at an acidic pH. We found that TCEP was suitable for partial reduction of bovine insulin deposited on the target and mixed with either sinapinic acid in MALDI or glycerol and m-nitrobenzyl alcohol in LSIMS. When TCEP was added to insulin deposited on the target without prior mixing of sinapinic acid the in situ MALDI protocol resulted in almost complete reduction.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070312
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  • 19
    Digitale Medien
    Digitale Medien
    Solvation of transition-metal ion complexes in the gas phase (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 848-852 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Solvation of the gas-phase transition-metal d0 complexes ScO+, YO+, YCHCN+ and NbO2+ with some protic and aprotic solvents has been studied using Fourier-transform ion cyclotron resonance mass spectrometry. The relative rate constants for formation of the solvated oxides show strong non-monotonic fluctuations with increasing extent of solvation. For ScO+ and YO+ the third solvent molecule attaches more rapidly than the second, while for NbO2+ the second attaches more rapidly than the first. This behavior suggests that in spite of the formal d0 character of the metal centers in these systems, simple electrostatic binding is not occurring. In contrast, YCHCN+ shows a continuous decrease in the rate for solvation with up to three molecules of CH3CN. The effects of solvation on the subsequent reactions of the metal oxides has been studied. YO+ solvation (with up to three H2O or two NH3 molecules) does not affect its arene C—H bond activation reactions. However, solvation of ScO+ and NbO2+ with one or two NH3 or H2O molecules shuts off benzene dehydrogenation.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070913
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  • 20
    Digitale Medien
    Digitale Medien
    High resolution accurate mass measurement of product ions formed in an electrospray source on a sector instrument (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 12-15 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The high resolution accurate mass measurement of product ions formed by collisionally activated dissociation in an electrospray source has been achieved using a reversed-geometry double-focusing mass spectrometer and accelerating voltage scans. Accurate mass measurements of product ions from angiotensin I, angiotensin II, leucine enkephalinamide, substance P (1-9) and a synthetic compound of pharmaceutical interest were obtained with an average error of 〈5 ppm.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070104
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  • 21
    Digitale Medien
    Digitale Medien
    Flow injection Thermospray® mass spectrometry for the automated analysis of potential agricultural chemicals (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 85-91 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Flow injection Thermospray mass spectrometry (TSP-MS) has been developed and utilized for molecular weight and structural confirmation for thousands of potential new agricultural chemicals. Initially, it was necessary to find TSP conditions which provide an optimal compromise between providing reproducible, informative mass spectra and being sufficiently universal and rugged for a wide variety of compound types. By acquiring both positive- and negative-ion spectra for each sample, the range of compounds that can be analyzed successfully is greatly expanded. The method developed is sufficiently universal that flow injection TSP-MS now provides the required information in approximately 70% of the mass spectrometric structural confirmations performed at the Agricultural Research Division of American Cyanamid. The success in using flow injection TSP-MS led to the development of instrumentation to fully automate these analyses. An IBM PC/AT® compatible computer is used to control sample delivery, data acquisition and data output. The PC performs the functions of both terminal and operator for a Finnigan® TSQ 46 triple quadrupole mass spectrometer and its Data General Nova® 4X data system, while simultaneously controlling a Micromeritics® 725 (Alcott®) autosampler and its Reodyne® 8126 pneumatically actuated 6-port sampling valve. Furthermore, the need to document analyses in a manner that is consistent with Good Laboratory Practices has led to automated documentation for the instrument analysis log, as well as for the headers of the electronic data files and the printed spectral output. The new automated flow injection TSP-MS system described here was constructed using only commercially available equipment and has notably improved efficiency by reducing the instrument time required to record spectra and by minimizing analyst intervention.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070118
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  • 22
    Digitale Medien
    Digitale Medien
    New methods for computational ion structure evaluation by means of tandem mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 99-105 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: New methods are presented for the evaluation of ion structures and fragmentation pathways using tandem mass spectrometry (MS/MS) with low energy collision-induced dissociation. As an aid for mass spectroscopists, they incorporate a PC software package (named PDNL, written in Turbo-PASCAL 5.5 (Borland), running under DOS (Microsoft) with mouse-control). A database of almost 300 low energy MS/MS spetra is available for library searches. It utilizes a new, intensity-based matching algorithm fitting to the demand of MS/MS data. Computational methods have been developed for (i) the separation of the spectra of unresolved isobaric ions and evaluation of the ratio of the ion abundances, (ii) the evaluation of single-collision spectra using the multi-collisional data map, and (iii) the elucidation of collision-induced dissociation fragmentation pathways. Principal component analyses of sets of at least eight MS/MS spectra were used for a quick comparison of these spectra and for a summary of inter-ion relationships.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070121
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  • 23
    Digitale Medien
    Digitale Medien
    Kinetics of isobaric ion/molecule reactions determined by the flowing afterglow-triple quadrupole technique (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 383-391 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: An experimental method is described for determining the kinetics of gas-phase ion/molecule reactions involving reactant and product ions with the same nominal or exact masses (i.e., isobaric ion/molecule reactions) using a flowing afterglow-triple qvadrupole instrument. The method involves formation of specific monitor ions in the triple quadrupole analyzer by collision-induced dissociation, exothermic ion/molecule reactions or energy-resolved ion/molecule reactions for use in determining the kinetics of reaction of one component of an isobaric ion mixture in the flow tube. The measured depletion of these types of monitor ions is shown to provide a reliable means of determining the rate coefficient for the overall reaction taking place when a neutral reagent is added to the flow reactor.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070515
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  • 24
    Digitale Medien
    Digitale Medien
    Does the mercuous diatomic dication exist in the gas phase? A search by mass spectrometryNRCC no. 34848. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 409-411 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070519
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  • 25
    Digitale Medien
    Digitale Medien
    Determination of saxitoxin by liquid chromatography/thermospray-mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 413-415 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The determination of the paralytic shellfish poison saxitoxin by liquid chromatography/thermospray-mass spectrometry (LC/TS-MS) was investigated. It was found that a commercial sample contained an impurity, which was identified as the plasticizer tris(2-butoxyethyl) phosphate. Spraying of saxitoxin in acid solution at pH 2 led to a useful TS mass spectrum, containing some fragment ions in addition to the protonated molecule. Using pentafluoropropionic acid as a counter-ion, saxitoxin could be determined by LC/TS-MS on a C18 re versed-phase column. By injecting the relatively large volume of 1 mL, a concentration of 30 ng/mL could be measured.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070602
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  • 26
    Digitale Medien
    Digitale Medien
    Gas chromatography/mass spectrometric analysis of urinary nucleosides in cancer patients; potential of modified nucleosides as tumour markers (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 427-434 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Analysis of urine from cancer patients by capillary gas chromatography/mass spectrometry positively identified 14 urinary nucleosides including several modified nucleosides. Levels of the modified nucleosides 1-methyl-adenosine, 2-methylguanosine, N2,N2-dimethylguanosine and 1-methylinosine as well as the total nucleoside level were elevated in the urine when a malignant tumour was present; the levels of N2,N2-dimethylguanosine were found to correlate with the stage of the cancer.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070605
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  • 27
    Digitale Medien
    Digitale Medien
    Calendar of events (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. ii 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290071020
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  • 28
    Digitale Medien
    Digitale Medien
    New developments in Archaeological Science EDITED BY A.M. POLLARD Published for The British Academy by Oxford University Press, 1992. 295 pp. £25 ISBN 0-19-726118-3. ISSN 0068-1202 (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 957-957 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290071019
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  • 29
    Digitale Medien
    Digitale Medien
    Quantification of abscisic acid using liquid chromatography/thermospray ionization tandem mass spectrometry for selected reaction monitoring (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1067-1069 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A liquid chromatography/thermospray ionization tandem mass spectrometry (LC/TSP-MS/MS) method was developed for the quantification of abscisic acid (ABA) in crude plant extracts without derivatization. By this technique interfering chemical background ions are eliminated and a detection limit for ABA olf 0.2 ng is achieved. Reproducibility for quantification is attained by parallel reaction monitoring of ABA and added ABA-d6 used as an internal standard. The standard curve is linear over the range 200 pg to 10 ng of injected ABA. As examples of the application of the methodology, the quantification of ABA in some plant tissues is given.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290071202
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  • 30
    Digitale Medien
    Digitale Medien
    Complete third-order resolution formulae for time-of-flight mass spectrometers incorporating reflectrons (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1095-1098 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The resolution of single- and double-stage, homogeneous electric mirror time-of-flight mass spectrometers can be calculated with the derived formulae for detectors located normally to the ion flight direction or parallel to the mirror face. These formulae account for contributions to the peak width from ion initial velocity and position in the source (‘turn around’ time included), from ion-packet longitudinal and transverse size at the source final grid, as well as due to the angular ion spread. Third-order terms are included for beam size, angular aperture and velocity spread, the incidence angle being small. The field-free space needed to obtain energy focusing in time is connected with the length of the accelerating space inside the source.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290071208
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  • 31
    Digitale Medien
    Digitale Medien
    Quantitative analysis of low molecular weight compounds of biological interest by matrix-assisted laser desorption ionization (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1090-1094 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Internal standards were used to demonstrate that matrix-assisted laser desorption/ionization (MALDI) mass spectrometry can be applied to the quantitative analysis of low molecular weight polar compounds. Three examples were tested: a standard curve for 3,4-dihydroxyphenylalanine (DOPA) was prepared using a stable isotope analogue (i.e., [13C6]DOPA) as an internal standard; [2H16]-acetylcholine was employed as an internal standard for the quantification of acetylcholine; and in the final example, the peptide Ac-Ser-Ile-Arg-His-Tyr-NH2 was used as an internal standard for the quantification of the peptide H-Ser-Ala-Leu-Arg-His-Tyr-NH2. In each instance, straight line fits (r2〉0.95) demonstrate that MALDI is a viable approach for the quantitative analysis of low molecular weight analytes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290071207
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  • 32
    Digitale Medien
    Digitale Medien
    An investigation into the stereochemistry of the boronate di-esters of some monosaccharides using tandem mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 1099-1107 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The aim of this work was to probe the stereochemistry of a series of monosaccharides. Firstly, the underivatized sugars were investigated using linked-scans and tandem mass spectrometry on a ‘hybrid’ instrument (hybrid MS/MS) and secondly, a comparison of linked-scan and hybrid MS/MS was carried out on the butyl and phenyl boronate di-esters. In situ derivatization of the sugar to the boronate di-ester allows a negative-ion fast-atom bombardment (FAB) investigation with greater sensitivity than for the underivatized sugar. The linked-scan data allow a great deal of information on the structure and chemistry of the sugars to be obtained, but the sensitivity at lower mass is limited. The hybrid MS/MS data give similar fragmentation information, plus improved sensitivity at lower molecular weight.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290071209
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  • 33
    Digitale Medien
    Digitale Medien
    Structural investigation of the hydroxy-propynal molecular ion (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 132-137 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A formyl ketenyl platinum derivative, trans-μ1-(PCy3)2(H)Pt[C(CHO)CO] (where Cy represents a cyclohexyl group), when reacted with HCl, gives a C3H2O2 species among the reaction products. The structure was investigated mass spectrometrically by study of the reactions of metastable ions, and the information gained was combined with data from theoretical calculations to rationalize the structure of the C3H2O2 molecule.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070204
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  • 34
    Digitale Medien
    Digitale Medien
    Matrix-assisted laser desorption time-of-flight mass spectrometry of oligonucleotides using 3-hydroxypicolinic acid as an ultraviolet-sensitive matrixPublication delayed to February 1993 at authors' request. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 142-146 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Matrix-assisted laser desorption time-of-flight mass spectrometry has been used to produce quasimolecular ion signals from underivatized mixed-base single-stranded DNA oligomers ranging from 10 to 67 nucleotides in length. These results were obtained with a new matrix material, 3-hydroxypicolinic acid (3-hydroxypyridine-2-carboxylic acid)which showed significant improvement over many previously reported matrices studied in terms of mass range available, signal-to-noise ratio, and the ability to analyze mixed base oligomers. The desorption and simultaneous ionization was by pulsed laser light at 10 to 50 mJ/cm2, studied at 266, 308, and 355 nm. Spectra taken at 266 nm provided the smallest amounts of doubly charged and dimer ions - characteristics desirable for DNA sequencing by this technology. Negative-ion spectra were uniformly superior to positive-ion spectra. This new matrix also is quite effective for molecular weight determinations of peptides and proteins in both positive- and negative-ion modes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070206
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  • 35
    Digitale Medien
    Digitale Medien
    Calendar of events (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. ii 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070215
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  • 36
    Digitale Medien
    Digitale Medien
    Charge-remote fragmentation of bile acids derivatized with amino-sulphonic acids (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 235-240 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Negative-ion fast-atom bombardment mass spectra of free and conjugated bile acids are dominated by [M — H]- pseudomolecularions. Collision-induced dissociations of these pseudomolecular ions give charge-remote fragmentation patterns which are useful for structural identification. Taurine (2-aminoethanesulrtionic acid)-conjugated bile acids have a high cross-section for charge-remote fragmentation, and give the most informative and intense spectra among the naturally occurring bile acids. In the present study, collision-induced dissociation spectra of bile acids derivatized with different aliphatic and aromatic aminosulphonates, and with 2-amlnoethyl hydrogen sulphate have been compared. All show charge-remote fragmentation patterns. Determination of the intensities of the fragment ions shows that the highest sensitivity is usually obtained with aromatic aininosulpho-nate derivatives.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070314
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  • 37
    Digitale Medien
    Digitale Medien
    Massenspektrometrie - Begriffe und Definitionen (mass spectrometry - terms and definitions). Ernst Schroeder. Publisher: Springer-Verlag, Heidelberg Taschenbücher, Berlin, 1991, pp. 95, DM 24.80, ISBN 3-540-53329-X (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 256-256 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070318
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  • 38
    Digitale Medien
    Digitale Medien
    Translational energy spectroscopy. I. Theory and practical considerations (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 272-281 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Non-dissociative collision processes are classified and the accepted notation is given. The basic kinematics of binary collisions are derived and practical considerations based on Massey's adiabatic criterion together with the effects of pressure and temperature are discussed. A general description of instrumental developments and the performance achieved are given and the predictions of the Wigner spin conservation rule as regards the spectroscopic states of the products are summarized.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070403
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  • 39
    Digitale Medien
    Digitale Medien
    Analysis of cyclic nucleotide-related enzymes by continuous-flow fast-atom bombardment mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 293-303 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Continuous-flow fast-atom bombardment mass Spectrometry has been developed to directly monitor cyclic nucleotide (substrate) and its product levels from an on-going phosphodiesterase reaction. Analysis of cAMP and cCMP phosphodiesterase incubates have been performed where the temporal evolution of the enzymic reaction is monitored and the effect of enzyme concentration upon the rate of reaction determined. Quantitative data on the enzyme kinetics have been obtained, in the form of Lineweaver-Burke plots, that are shown to correlate well with well-established radiometric methods.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070407
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  • 40
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993) 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070501
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  • 41
    Digitale Medien
    Digitale Medien
    Dilithiated fragments of a monolithiated precursor ion? Unraveling linked scan spectra at constant B/E using labeled lithium ions (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 320-322 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Liquid secondary-ion mass spectra of the macrocyclic immunosuppressant rapamycin, ionized from a matrix containing lithium chloride, show intense [M + Li]+ peaks and little or no [M + 2Li - H]+. Linked scanning, at constant B/E, of the [M + Li]+ ion proved difficult to interpret, so a labeling experiment using 6LiCl was performed. Several prominent fragments were observed to contain two lithium ions, and precursor ion scans (constant B2/E) confirmed that these were derived from a metastable [M + 2Li - H]+ precursor. Due to poor precursor-ion resolution in fragment-ion scans at constant B/E, mono- and dilithiated precursors separated by only 6 u may produce fragments observed in each other's spectra. We find that use of labeled 6LiCl quickly and simply alleviates interpretation problems associated with this effect.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070503
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  • 42
    Digitale Medien
    Digitale Medien
    The collision-induced fragmentations of deprotonated allyl alcohol and its monomethyl derivatives (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 336-338 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Deprotonated allyl alcohol undergoes collision-induced losses of H2, CH2O and C2H4 with minor hydrogen randomization occurring prior to or during these dissociations. A further fragmentation involves loss of methane: labelling studies (with CH2=CH—CD2O-) suggest that this loss is preceded by the equilibration CH2=CH—CD2O- ⇌ CD2=CH—CH2O-. The methyl homologues of allyl alcohol form isomeric C3H5- ions: the charge reversal spectra of these isomers confirm that CH2=CH—CH2-, CH2=C̄C—Me and HC̄=CH—Me are separate species, and also suggest that all three of the corresponding positive ions are formed on the charge-reversal time-scale.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070506
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  • 43
    Digitale Medien
    Digitale Medien
    Detection and characterization of fumonisin mycotoxins as their methyl esters by liquid chromatography/particle-beam mass spectrometryPRC contribution no. 1462. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 352-359 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The diazomethane-derived tetramethyl esters of fumonisins can be introduced readily into mass spectrometers using flow injection analysis or liquid chromatography (LC) via a particle-beam interface to yield chemical ionization and electron-ionization spectra. The esters of fumonisins B1, B2, and B3 were well resolved on a C18 reversed-phase column when eluted with a gradient of water + methanol + acetonitrile in the presence of 0.05% trifluoroacetic acid. Enhancement of analyte transport through the particle-beam interface to afford increased ion abundances was achieved by addition of carriers. Polyfunctional amino acid carriers, such as L-glutamic acid or L-serine, effected at least 100-fold increases in sensitivity. In the LC mode, post-column addition of aqueous L-serine was the most advantageous because background interference was limited to lower masses, and because of higher solubility, and ease of cleaning.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070509
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  • 44
    Digitale Medien
    Digitale Medien
    Species-selectivity effects in the production of electrospray ions (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 363-373 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Positive- and negative-ion production from electrosprayed charged liquid droplets has been studied. For acidified solutions of arginine, Arg-Arg-Arg, Lys-Lys, and (CH3)4NBr in methanol + water (80/20, v/v), the relative intensities of CH3OH2+ ions were found to decrease faster than those of other sample ions as the distance (d) between the capillary tip and the interface plate was increased. The radial distribution of ion intensities in the spray cone was also examined. While the CH3OH2+ ions and multiply charged ions had maximum intensities in the central region of the spray cone, NH4+ and singly charged oligopeptide ions were found to be distributed in its peripheral region. The observed species-selectivity effects in the production of electrospray ions were interpreted in terms of the volatility of ions in the charged liquid droplets. The negative-ion intensities of the oligopeptide Glu-Glu were enhanced greatly when ammonia was added to the solution. An optimum ammonia concentration which gives the strongest negative-ion signals was ∼10-4M.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070511
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  • 45
    Digitale Medien
    Digitale Medien
    Plasma desorption mass spectrometry of anthocyanidins (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 400-403 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Plasma desorption mass Spectrometry (PDMS), developed for the mass analysis of biopolymers, has found application in the analysis of anthocyanidins, an important class of color-producing compounds in plants. Anthocyanidins, which have hitherto proven extremely difficult to analyze by any type of mass spectrometric technique, can be analyzed routinely to nanogram levels using PDMS. A simple extraction/hydrolysis scheme can be used to screen for these compounds.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070517
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  • 46
    Digitale Medien
    Digitale Medien
    Calendar of events (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. ii 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070520
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  • 47
    Digitale Medien
    Digitale Medien
    Mass spectrometric investigation of the evaporation properties of Ba2CaWO6 and Ba2SrWO6 (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 416-420 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The vaporization of Ba2CaWO6 and Ba2SrWO6 was investigated by Knudsen-cell mass spectrometry. According to the results obtained with a Knudsen cell made of tungsten, the reduction of barium-calcium tungstates is a non-equilibrium process whereas the sublimation of BaWO4 and its decomposition in the gas phase to BaO(g) and WO3(g) are equilibrium reactions. From the temperature dependence of the partial pressure BaWO4(g) the enthalpy of sublimation is obtained as ΔHToII = 469 ± 4kJ/mol, which is in excellent agreement with the value obtained by third-law calculations. The origin of the most abundant ions in the gas phase, i.e., BaWO4+, BaWO3+, BaO+ Ba+ etc, has been explained from measurements of the corresponding ionization energy (IE) and appearance energy (AE) values.The difference between the AE values for Ba2CaWO6 and Ba2SrWO6 is negligible. The presence of BaWO4 in the condensed phase was confirmed by X-ray diffraction measurements. Neither X-ray analysis nor the mass spectra show the presence of CaWO4 or SrWO4 in the solid phase or in the gas phase.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070603
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  • 48
    Digitale Medien
    Digitale Medien
    Laser mass spectrometry of oligonucleotides with isomer matrices (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 435-439 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Various isomer matrices were used for laser-desorption ionization of mixtures of oligomers. It was found that the efficiency of production of oligomer ions changed drastically when different isomers were used as matrices. For selected matrix materials, parent oligomer ions with sizes up to 64 bases were observed.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070606
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  • 49
    Digitale Medien
    Digitale Medien
    Spontaneous desorption: Dependence of the desorption rate on the grid parameters (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 446-448 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The desorption rate for ‘spontaneous desorption’ (SD) has been investigated using various grids with different geometrical dimensions (line width, line distance). The experimental results can be understood if one assumes that the keV ions which sputter ions from the sample in an SD process originate exclusively at the grid via field-enhanced desorption of adsorbates (FEDA). This means that SD is a two-step process. The first step is FEDA, the second step is a sputter process.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070608
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  • 50
    Digitale Medien
    Digitale Medien
    Mass spectral fragmentation patterns of unsymmetric furylacrylic acid dicarbonyldichlorides and dianilides: 2,3-dichloro-3-(5-chloro-carbonyI)-2-furyl-acrylcarbonylchloride and 2,3-dichioro-3-(5-anilido-2-furyi)-2-acrylcarbonylanilide (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 460-461 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Electron ionization mass spectrometry is shown to provide a valid analytical toot for the structural characterization of the title compounds. Diagnostic fragmentation pathways of an unsymmetrically substituted 2,5-furan dicarbonyl dichloride and dianilide were observed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070611
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  • 51
    Digitale Medien
    Digitale Medien
    Desorption-ionization and in-flight fragmentation of monoalkali-glycine adducts: Plasma-desorption mass spectrometry and Ab initio calculations (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 470-476 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Interpretation of 252Cf plasma-desorption mass spectra of glycine and alkali salt mixtures is correlated to thermochemical values. The interpretation of direct spectra is based on a model considering competitive fragmentations among the ionic bonds involved in the crystalline structure; the desorption yield of Li, Na, K, Rb and Cs alkali-glycine adduct ions is shown to depend upon the relative lattice energies of the different salts bound in the solid mixture. Ab initio calculations were performed at the 6-31G*//3-21G level to evaluate the dissociation energies associated with the in-flight decomplexation reactions GlyCat+ → Gly + Cat+ (1) for Cat+ = Li+, Na+ and K+ whether we consider that the GlyCal+ desorbed species enter the field-free area in their ‘preformed geometry’ or that they rearrange during the acceleration step. The experimental metastable transition rates associated with these reactions were determined to be in good agreement with the theoretical values for both GlyCat+ geometries under consideration. We calculated the cation affinities of glycine to be 271 kJ/mol, 188kJ/mol and 127kJ/mol for Li+, Na+ and K+, respectively. The fragmentation of GlyCat+ species into immonium ions, GlyCat+ → [H2N-CH2]+ + CO + HOCat (2), is also experimentally and theoretically investigated. The competition between reactions (1) and (2) is favourable to (2) for Cat+ = H+ and to (1) for Cat+ = Li+, Na+ and K+. From both competitive reactions, the comparison between theoretical values and experimental observations allows one to estimate the average internal energy of the GIyCat+ desorbed species at about 300 kJ/mol in the field-free area of the mass spectrometer.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070614
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  • 52
    Digitale Medien
    Digitale Medien
    Selective elimination of low-molecular-weight ions in MALDI-TOF mass spectrometry using a bipolar pulsed electrostatic particle guide (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 502-506 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: This study addresses a problem inherent in the use of microchannel plates as detectors for matrix-assisted laser desorption/ionization. We have developed a unique new method of ion transport using fast bipolar pulsing of an electrostatic particle guide to provide ion deflection and enhanced ion transmission. This mode of operation effectively eliminates the intense low-mass component of the spectrum which normally saturates microchannel -plate detectors, while at the same time transporting the higher-mass component with high efficiency. Enhancement of the resulting signal-to-noise ratio has been achieved.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070620
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  • 53
    Digitale Medien
    Digitale Medien
    Direct observation of UV-crosslinked protein-nucleic acid complexes by matrix-assisted laser desorption lonization mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 496-501 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Interactions between proteins and nucleic acids arc important in the fundamental cellular processes that drive replication, recombination, dynamic alteration and repair of DNA, transcription and processing of RNA, synthesis of proteins, and regulation of enzyme activities. As part of an effort to develop a general, sensitive mass spectrometric strategy for the characterization of protein-nucleic acid interactions, we have used matrix-assisted laser desorption-ionization (MALDI) time-of-flight mass spectrometry to analyze protein-nucleic acid complexes that have been covalently crosslinkcd by ultraviolet (UV) light. In general, the application of MALDI mass spectrometric techniques to studies of U V-induced crosslinking of nucleoprotein complexes is demonstrated to be feasible. Specifically, MALDI mass analysis was used to determine the molecular weights of the phage T4 gene 32 protein (gp32) crosslinked to the oligonucleotide (dT)20, and the Escherichia coli transcription termination factor rho, photoaffinity labeled with 4-thio-uridine-diphosphate (4sUDP). The covalent gp32:(dT)20 complex is readily detected at a concentration of 1-2 μM in 1 μL of an unpurined solution of reactants thai has been exposed to a single, 266 nm UV laser pulse. Mass spectrometric molecular weight determinations of the covalent rho:4sUDP complex add directness and specificity to the ATPase inactivation assay normally used to monitor the formation of 4sUDP photoafluiity labeled rho. It is found that successful MALDI mass spectrometry of protein-nucleic acid complexes is as critically dependent on the choice of solvents and additives as it is on the primary matrix compound.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070619
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  • 54
    Digitale Medien
    Digitale Medien
    Contributions of fast-atom bombardment mass spectrometry to studies of cyclic nucleotide biochemistry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 528-537 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Cyclic nucleotides are biochemical second messengers which mediate the actions of many hormones and neurotransmitters. Fast-atom bombardment (FAB) mass spectrometry and mass-analysed ion kinetic energy (MIKE) spectra have provided a means of unambiguous identification of these compounds, and in addition to identifying endogenous putative cyclic nueleotides and their synthetic analogues FAB/MIKE analysis has now been applied to good effect to both qualitative and quantitative studies of cyclic nuclcotide-related enzymes. Here the application of this mass spectrometric technique to cyclic nucleotides is described and its impact upon this field reviewed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070626
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  • 55
    Digitale Medien
    Digitale Medien
    Double-charge-transfer spectroscopy using a modified Finnigan 8230 spectrometer (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 548-551 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A Finnigan 8230 mass spectrometer has been converted to a translational-energy-loss spectrometer suitable for double-charge-transfer (DCT) spectroscopy. Its performance was investigated by obtaining DCT spectra when 3keV OH+ projectile ions interacted with xenon atoms and ethene molecules. Well-separated peaks were obtained which correspond to the populating of dicationic electronic states differing in energy by about 1 eV.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070629
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  • 56
    Digitale Medien
    Digitale Medien
    Official opening of the institute of mass spectrometry of the University of Amsterdam, the Netherlands, 23 april 1993 (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 567-567 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070633
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  • 57
    Digitale Medien
    Digitale Medien
    Calendar of events (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. ii 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070635
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  • 58
    Digitale Medien
    Digitale Medien
    Electron-ionization mass spectra of aminomethyltetrathiafulvalenes (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 587-590 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Electron-ionzation mass spectra of aminomethyltetrathiafulvalenes were studied by exact mass measurements and metastable-ion analysis. Cleavages of the C-N bond and the exocyclic C-C bond with or without hydrogen rearrangement are the most characteristic fragmentations for these compounds. Ions at m/z 204 and 134 were characterized as tetrathiafulvalene and l,3-dithiol-2-thione molecular ions by collisional activation.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070705
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  • 59
    Digitale Medien
    Digitale Medien
    New desorption strategies for the mass spectrometric analysis of macromoleculesPaper presented 3 June, 1993, at the 41st ASMS conference in San Francisco, CA, USA. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 576-580 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: We present two new desorption strategies for the mass spectrometric analysis of macromolecules. These desorption strategies are based on the molecular design and construction of two general classes of sample ‘probe’ surfaces. The first class of surfaces is designed to enhance the desorption of intact macromolecules presented alone (neat) to the surface; we call this surface-enhanced neat desorption (SEND). The availability of probe surfaces derivatized with, or composed of, multiple types and defined numbers of energy-absorbing molecules will facilitate investigations of energy transfer and desorption/ionization mechanisms. The second class of probe surfaces is designed to enhance the desorption of specific macromolecules captured directly from unfractionated biological fluids and extracts; we call this surface-enhanced affinity capture (SEAC). Use of these new probe surfaces as chemically defined solid-phase reaction centers will facilitate protein discovery through molecular recognition in situ, and also macromolecular structure analysis through the sequential chemical and/or enzymatic modification of the adsorbed analyte in situ. Specific examples of laser-assisted SEND and SEAC time-of-flight mass spectrometry are presented to illustrate the potential for increased selectivity, analyte detection sensitivity, and mass measurement accuracy.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070703
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  • 60
    Digitale Medien
    Digitale Medien
    Investigating the non-covalent interaction of cytidylic acids, with Ribonuclease A by electrospray mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 603-604 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Electrospray mass spectrometry has been applied to probe the binding of 2′-CMP,3′-CMP and 2′3′-CMP to RNaseA. Results show that, in the presence of excess amounts of these molecules, binding also appears to occur at a secondary site on the enzyme.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070709
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  • 61
    Digitale Medien
    Digitale Medien
    Electron impact ionization of H2O ice (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 620-622 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Electron impact ionization and dissociative ionization of water in vapour and ice form has been studied using a newly developed apparatus comprising a well-collimated beam of 700 eV electrons, a cryogenic target assembly and a quadrupole mass spectrometer. The target assembly consists of a liquid-nitrogen cooled nickel foil upon which a thin layer of ice is formed. Comparison of the vapour-phase mass spectrum with that obtained in the ice phase reveals significant differences in the dissociative ionization pattern which are of significance in modelling studies of cold astrophysical environments.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070713
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  • 62
    Digitale Medien
    Digitale Medien
    Collision-induced dissociations of deprotonated peptides. Dipeptides containing methionine or cysteine (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 623-625 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The collisional activation mass spectra of the [M - H]- ions of dipeptides containing Met or Cys show the usual backbone fragmentation allowing the sequence of the peptide to be determined. A methionine residue may be identified by the presence of a pronounced peak resulting from loss of MeSH, while a cysteine residue may be identified by the presence of a peak corresponding to loss of either H2S or (H2S + CO2).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070714
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  • 63
    Digitale Medien
    Digitale Medien
    Ion trap and quadrupole mass spectra of lignin pyrolysates: How well do they compare?Paper delivered at the llth Informal Meeting on Mass Spectrometry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 641-645 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Lignin samples from wheat straw, orchard grass, red clover and a synthetic lignin were subjected to pyrolysis gas chromatography/mass spectrometry using both quadrupole (QMS) and ion-trap detector (ITD). ITD mass spectra were comparable with those presented in the National Bureau of Standards (NBS) library and with those obtained by QMS as evaluated by discrepancy factors. Computer-assisted library searches for ITD spectra were successful for 22 of 47 compounds. The other 25 compounds were not present in the library. A typical program and mass spectra are shown. Statistical data are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070717
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  • 64
    Digitale Medien
    Digitale Medien
    The potential of pyrolysis - (methylation)/gas chromatography/mass spectrometry in the analysis of wine polyphenolicsPaper delivered at the 11th Informal Meeting on Mass Spectrometry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 656-658 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The phenolic compounds of a red Italian wine were separated by column chromatography into three fractions: (a) monomers, (b) red polymers and (c) yellow and brown polymers (tannins). Polymers were subjected to pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) using a heated-filament pyrolyzer coupled to a capillary gas chromatograph and an ion-trap-detector mass spectrometer. Samples were pyrolysed as such or mixed with an aqueous solution of tetramethylammonium hydroxide in order to perform a simultaneous pyrolysis-methylation (SPM). Pyrograms showing diagnostic markers for flavonoids and phenolic acids are reported. Advantages and limitations of both PY/GC/MS and SPM/GC/MS are discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070720
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  • 65
    Digitale Medien
    Digitale Medien
    Identification of molecular masses up to 270 000 u in coal and coal-derived products by matrix-assisted laser desorption mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 795-799 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Molecular masses up to 270 000 u have been observed during matrix-assisted laser desorption mass spectroscopy on a sample of bituminous coal; the major fraction of desorbed ions appeared between m/z values of 800 and 5000. Similar mass distributions have been found in a coal-liquefaction extract and a pyrolysis tar. The highest molecular masses identified in this work far exceed previously reported high molecular masses found in coal-derived products (12 000 u), which were also detected by laser-desorption mass spectrometry.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070903
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  • 66
    Digitale Medien
    Digitale Medien
    Electron impact mass spectrometry and metastable ion studies on 2-[3-hydroxy-2-pyridyi]-2-(3h)-thiazolimine and 1,3,4-thiadiazine derivatives (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 449-453 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The mass spectrometric behaviour of some 2-[3-hydroxy-pyridyl]-2-(3H)-thiazolimine and 1,3,4-thiadiazine derivatives was studied in detail under electron ionizing conditions by means of accurate mass measurements, deuterium-labelling experiments and metastable ion studies. The resultant fragmentation patterns were highly complicated with cleavage of the amine bond and of the thiazoline ring. The main differences between the decomposition mechanism of thiazoline and thiadiazine derivatives lies in the retro-synthetic ring transformation processes, observed in the case of thiadiazine compounds only.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070609
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  • 67
    Digitale Medien
    Digitale Medien
    Analysis of clenbuterol in human plasma using liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 462-464 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Clenbuterol is a β-agonist drug used illegally as a growth stimulant in meat-producing animals and human athletes. The analysis of clenbuterol in spiked human plasma was performed using on-line liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry (LC/APCI-MS) using a conventional bore LC column (flow rate = 1.0 mL/min). At low sampling cone voltages, the mass spectrum was predominantly the [M + H]+ ion but diagnostic fragment ions were formed upon incremental increases in sampling cone voltage. The detection limit (signal-to-noise ratio of 3) using selected-ion monitoring of the [M + H]+ ion was 0.1 ng on-column (l0 ppb). This is a 50-fold better sensitivity of detection than that previously reported for an on-line thermospray LC/MS method. The extraction procedures were not optimized for maximum sensitivity and the lack of interferences suggests that much lower detection limits for clenbuterol in plasma are attainable.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070612
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  • 68
    Digitale Medien
    Digitale Medien
    High-performance liquid chromatography/mass spectrometry with thermospray lonization of free ecdysteroids (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 477-481 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: High-performance liquid chromatography/mass spectrometry (HPLC/MS) with thermospray ionization has been applied to the analysis of free ecdysteroids (polyhydroxylated steroids that serve as arthropod moulting hormones). Of a range of analytical conditions that were tested, optimum results were obtained by the use of re versed-phase HPLC using a methanol + water mixture containing 0.1 M ammonium acetate. The positive-ion spectra of ecdysteroids showed pseudo-molecular ions, [M + H]+, and fragment ions corresponding to the sequential losses of hydroxyl groups. The [M + H - H2O]+ and [M + H - H2O]+ ions were the most abundant for all the compounds tested. Ecdysteroids bearing a C-20 hydroxyl group (e.g. 20-hydroxyecdysone) showed ions characteristic of cleavage of the side-chain from the steroid nucleus. This mode of fragmentation was much less obvious in the case of ecdysteroids lacking C-20 hydroxylation (e.g. ecdysone). Full-scan mass spectra were readily obtained from 1 μg of free ecdysteroids, while a limit of detection of 5 ng (signal-to-noise ratio 3) was attained in the selected-ion monitoring mode. The application of HPLC/MS to the study of ecdysteroids in biological materials is demonstrated by the analysis of extracts of newly laid eggs of the desert locust (Schistocerca gregaria) and pupae of the cotton leafworm (Spodoptera litoralis).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070615
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  • 69
    Digitale Medien
    Digitale Medien
    Fast-atom bombardment/mass-analysed ion kinetic energy spectrometry of inositol phosphates (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 555-560 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The application of fast-atom bombardment mass Spectrometry and collisiorutlly induced dissociation with mass-analysed ion kinetic energy (CID/MIKE) Spectrometry of representative inositol mono-, bis- and trisphos-phates is described. Based on their CID/MIKE spectra, inositol polyphosphates containing vicinal phosphate groups could be distinguished from isomers in which adjacent phosphate groups were absent. The potential value of this procedure in studies of the biochemistry of intracellular second messengers is discussed.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070631
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  • 70
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993) 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070701
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  • 71
    Digitale Medien
    Digitale Medien
    Simultaneous detection of ions and neutrals produced by matrix-assisted laser desorption (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 569-575 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Ionic and neutral products of matrix-assisted laser desorption were simultaneously detected in a time-of-flight mass spectrometer. The neutrals were photoionized with coherent vacuum ultraviolet radiation. Mass spectra were obtained for primary and secondary alkyl amines in various absorbing matrices. Based upon relative signal intensities of directly formed analyte ions and photoionized analyte neutrals, the ratio of neutrals-to-ions ejected was found to be of the order of 10000 or greater with desorption irradiances near the threshold for ion formation. The ratio decreased with increasing irradiance of the desorption laser beam. This dependence is consistent with a collisional mechanism tor analyte-ion formation during the desorption event that is initiated by photoionization of the matrix. Matrices which gave large signal intensities of directly formed analyte ions also gave large signal intensities of photoionized analyte neutrals. Conversely, matrices which gave small signal intensities of directly formed arelyte ions also gave small signal intensities of photoionized analyte neutrals. These results suggest that the efficiency of analyte vaporization by matrix-assisted laser desorption is an intrinsic property of the matrix-analyte pair, independent of the ion-formation process.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070702
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  • 72
    Digitale Medien
    Digitale Medien
    Mass spectrometric location of double-bond position in isomeric dodecenols, without chemical derivatization (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 591-593 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A new procedure is presented for locating double-bund position in dodecenols. Ten isomers of chemically unmodified dodecenol were analysed by two kinds of mass spectrometers. A series of spectra obtained with a magnetic sector instrument were interpreted by analysing the similarity of mass spectral patterns based on a ‘fuzzy’ reasoning method, in which the intensity ratios of six diagnostic pairs of the predominant ions were defined as standard parameters. The method was tested with other series of spectra from a quadrupole mass spectrometer, and the original double-bond position in each isomer was located unambiguously.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070706
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  • 73
    Digitale Medien
    Digitale Medien
    Superbases in the gas phase: Amidine and guanidine derivatives with proton affinities larger than 1000 kj mol-1Dedicated to Professor R. W. Taft on the occasion of his 70th birthday. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 599-602 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: By building a relative basicity ladder, the current basicity scale (Lias et al., J. Phys. Chem. Ref. Data, 17 Suppl. No. 1 (1988)) has been reexamined in its upper part, and extended for organic compounds (amenable to proton transfer measurements) up to proton affinity, PA = 1050 kJ mol-1. Structural effects involved in superbasicities are briefly discussed and routes to further extension of the gas-phase basicity scale for organic compounds are proposed.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070708
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  • 74
    Digitale Medien
    Digitale Medien
    Ionization of C60 (buckminsterfullerene) by electron impact (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 610-613 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Utilizing a crosses electron-beam/molecular-beam collision geometry, mass spectra of C60 and C70 ions have been obtained for an electron impact energy range of 20 eV to 600 eV. These spectra are dominated by singly and doubly ionized species. The intensity of fragment ions is very weak, which is in agreement with previous observations. Ionization efficiency curves for the formation of C60+ and C602+ have also been obtained near their threshold regions. From these curves, appearance energies (AE) of these ions have been derived. The AE for C60+ is found to be 7.8±0.3 eV, which agrees well with previous measurements. However, our value of 16.4±0.3 eV for the formation of C602+ is much lower than the value of 19.0±0.3 eV obtained by photo-ionization techniques.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070711
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  • 75
    Digitale Medien
    Digitale Medien
    Analysis of taxol and related taxanes from taxus canadensis using liquid chromatography combined with mass spectrometry or tandem mass spectrometryNRCC No. 34868 (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 626-634 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A liquid chromatography/mass spectrormetry (LC/MS) method using nebulizer-assisted electrospray (ionspray) is described for the analysis of taxol and related taxane analogs in plant extracts from Taxus canadensis. The method used a reverse-phase liquid chromatography gradient elution which was entirely compatible with the operation of ionspray ionization. Abundant protonated molecules with limited fragmentation were obtained using this ionization technique, and provided adequate sensitivity for monitoring taxol in crude resin extracts. The LC/MS method was evaluated for the analysis of taxol present at levels of 0.2% in resin extracts. Using selected-ion monitoring, the method provided detection limits of 50 ng/mL. In addition, other taxane analogs were identified in crude resin extracts using liquid chromatography combined with tandem mass spectrometry. Parent-ion scans for a fragment ion characteristic of the taxane nucleus provided the necessary selectivity and sensitivity for the identification of potentially active diterpenes in complex extracts.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070715
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  • 76
    Digitale Medien
    Digitale Medien
    Doubly charged ions: Differentiation of flavanone and 2′-hydroxy chalconePaper delivered al the 11th Informal Meeting on Mass Spectrometry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 635-640 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The metastable and collision-induced decompositions of the singly charged molecular ions of flavanone and of 2′-hydroxy chalcone were obtained using mass-analysed ion kinetic energy spectrometry. Using the same method, neutral losses from, and charge separation reactions of, the doubly charged molecular ions were also determined. The fragmentation characteristics of the doubly and singly charged ions were found to be completely different. Comparison of the spectra of the isomers indicated that both the reactive and unreactive singly charged molecular ions lose their structural identity by the time they reach the second field-free region; flavanone ions probably isomerize to 2′-hydroxy chalcone ions. The corresponding doubly charged molecular ions, on the other hand, do not isomerize, and their spectra are quite distinct. This result suggests that spectra of doubly charged ions may, in some cases, be more suitable for the characterization of isomers than singly charged ions.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070716
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  • 77
    Digitale Medien
    Digitale Medien
    Pyrolysis/gas chromatography/mass spectrometry of lignin from paper-industry effluents decolorized by trametes versicolorPaper delivered at the 11th Informal Meeting on Mass Spectrometry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 659-661 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The pyrolysis/gas chromatography/mass spectrometry (PY/GC/MS) results after fungal treatment of paper-industry effluents suggested a decrease of the relative amounts of lignin pyrolysis products and of the syringyl/guaiacyl ratio, in addition to some oxidation rate of the C3-alkyl chain in lignin units. The results obtained pointed to the potential of PY/GC/MS for monitoring the extent of fungal modification of lignins by biological systems based on the use of Trametes versicolor.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070721
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  • 78
    Digitale Medien
    Digitale Medien
    Investigation of some steroids by means of thermospray and tandem mass spectrometryPaper delivered at the 11th Informal Meeting on Mass Spectromeetry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 673-675 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The detection limits of a number of steroids have been determined by means of loop-injection thermospray (TS) mass spectrometry. The measured limits were found to be in the range 1 pg-1O ng/μL. Combined positive-ion TS/tandem mass spectrometry yielded clear qualitative differences between mass selected protonatcd testosterone and estriol ions, both of which have the same nominal molecular weight. These differences are necessary for the correct identification of either species which may be present within a complex mixture. The heights of the peaks due to the two competing reaction channels, [M + H]+ and [M + NH4]+, were monitored as a function of the repeller voltage in the range 100-350 V, and the implications of the acquired data are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070725
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  • 79
    Digitale Medien
    Digitale Medien
    Investigation of some thiosulfonate derivatives by means of chemical ionization and tandem mass spectrometryPaper delivered at the 11th Informal Meeting on Mass Spectrometry, Budapest, 1993. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 670-672 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A number of thiosulfonate derivatives have been investigated by means of ammonia chemical ionization (NH3-CI), electron impact ionization (El) and mass-selected collision induced dissociation (CID). For most of the compounds investigated, the NH3-CI positive-ion mass spectra exhibit the addition ion, [M + NH4]+, as the dominant species, which implies that the proton affinities of the compounds investigated are less than the proton affinity of NH3. Deviation from true chemical ionization conditions resulted in efficient dissociation of the addition ion to yield substantial amounts of the protomated molecule, [M + H]+. The major fragment ions observed in the EI mass spectra and in the CID spectra indicate the cleavage of the sulfur-sulfur bond to be more efficient than other competing cleavages. This and other experimental observations are discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070724
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  • 80
    Digitale Medien
    Digitale Medien
    A new reduction process in fast-atom bombardment mass spectrometry: Transformation of an azido group into an amino group (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 704-706 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A new example of the reduction phenomenon often observed in fast-atom bombardment mass spectrometry is described, involving the transformation of an azido group into an amino group. This reaction, noticeable with glycerol as a matrix, does not occur with m-nitrobenzylalcohol.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070804
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  • 81
    Digitale Medien
    Digitale Medien
    Optimization of a commercial liquid chromatography/mass spectrometry interface by statistical experimental design (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 722-724 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The efficiency of delivering 4-methoxy phenyl acetic acid particle beam emerging from a commercial liquid chromatography/mass spectrometry interface into the ion source of the mass spectrometer was optimized using response surface modeling (RSM) of the statistical experimental design. It was found that the temperature and pressure of the nebulizer, and the temperature of the desolvation chamber are the major factors for the optimization.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070808
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  • 82
    Digitale Medien
    Digitale Medien
    Fast-atom bombardment mass spectrometric analysis of cyclic nucleotide and nucleotide triphosphate analogues used in studies of cyclic nucleotide-related enzymes (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 725-733 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Two isomers of adenosine 3′,5′-cyclic monophosphate, which show agonist and antagonist activity with cyclic AMP-dependent protein kinase, were found to yield essentially identical positive-ion fast-atom bombardment (FAB) mass spectra, but S1 and S2 fragments of differing relative intensities in their collision-induced dissociations, studied using mass-analysed ion kinetic energy (CID/MIKE) spectra. Halogen-substituted cyclic nucleotides, used in differentiating between protein kinase cyclic nucleotide binding sites, produced FAB mass spectra and CID/MIKE spectra with fragmentations generally analogous to those of the parent cyclic nucleotides; the bromo-derivatives showed a greater propensity for dehalogenation than the chloro-derivatives. The adenosine triphosphate analogues, adenylyl-(β,γ-methylene)-diphosphate and adenylyl-imidodiphosphate, alternative substrates for adenylyl cyclase, showed similar fragmentations with the methylene and imido groups blocking cleavage between the β and γ phosphate groups. The fragmentations observed are discussed in the context of the use of these compounds in the assay of protein kinase and adenylyl cyclase activity by quantitative mass spectrometry.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070809
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  • 83
    Digitale Medien
    Digitale Medien
    Oxidation of peptides during electrospray ionization (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 738-743 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: [M+H+16]+ ions were observed in the electrospray ionization mass spectra of several synthetic and maturally occurring peptides. Initial results have shown that the appearance of the modification is dependent on the field strength at the electrospray needle and the flow rate of the solution passing through the capillary. Mass spectrometric experiments on peptides showing the +16 Da modification attributed the change to the selective oxidation of either a methionyl, tryptophanyl, or tyrosyl residue present in the peptide. These results were further confirmed by tandem mass spectrometry experiments on prptides with a methionyl residue at either the N- or C-tgerminus, or within the peptide chain. This effect can occur under normal operating conditions and therefore care must be taken in the analysis of samples containing these oxidizable residues. Conversely, the selectivity of the oxidative process may be used to enhance the information obtained from the mass spectrometric analysis. For example, we show results for the analysis of a tryptic digest of the protein myoglobin where the occurrence of the [M+H+16]+ ion is used, along with the molecular weight data, to correctly identify the tryptic fragment.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070811
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  • 84
    Digitale Medien
    Digitale Medien
    Use of an on-line liquid chromatography trapping column for the purification of protein samples prior to electrospray mass spectrometric analysis (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 744-746 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A number of reagents, commonly used in protein chemistry and purification, suppress the electrospray ionization signal response of proteins in a concentration-dependent manner. An on-line trapping column device has been developed which enables the purification of protein samples containing these reagents, prior to their introduction into the mass spectrometer ion source.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070812
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  • 85
    Digitale Medien
    Digitale Medien
    Collision-induced dissociation and charge-reversal processes of isomeric C6H4X- (X = F, Cl and Br) anions (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 749-756 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The NH2- ion reacts with fluoro- and chlorobenzene in the cell of a Fourier-transform ion cyclotron resonance instrument only by proton abstraction, whereas the reaction with bromobenzene also yields Br- ions. The deprotonation of these halogen-substituted benzenes occurs the 2-, 3- or 4-positions as revealed by deuterium labelling in combination with high kinetic energy (8keV) collision-induced dissociation (CID) experiments performed with a double-focusing quadrupole hybrid mass spectrometer. The 2-fluoro- and 3- fluorophenyl anions eliminate HF following collision with an oxygen molecule. By contrast, the collisions between 4-fluorophenyl anions and O2 do not yield detectable amounts of negatively charged fragment ions owing to the exclusive occurrence of electrom detachment. Electron detachment is also the only process observed in the 8 keV CID experiments with chlorophenyl anions and 3- and 4-bromophenyl anions, whereas the ion formed by proton abstraction from the 2-position in bromobenzene dissociates to Br- and 1,2-dehydrobenzene. The 8 keV collision-induced charge-reversal spectra of the anions formed by proton abstraction from the 2-, 3- or 4-positions in a given halogen-substituted benzene are virtually identical, indicating that this method does not provide insight into the position of the charge with respect to the halogen atom in the substituted phenyl anions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070814
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  • 86
    Digitale Medien
    Digitale Medien
    On the mechanisms of electron-impact-induced sulfur dioxide elimination from the molecular ions of 4-nitro- and 6-nitro-2,1-benzisothiazoline 2,2-dioxide derivatives (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 763-768 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: It is shown that metastably decomposing molecular ions of the title compounds eliminate sulfur dioxide via two reaction pathways provided that an α-hydrogen atom adjacent to the heterocyclic ring nitrogen atom is present. One of the channels leads to the initial formation of an o-azaxylylene ionic species and is associated with the narrow component of the accompanying composite metastable peak. The other channel involvel a multistep pathway which eventually leads to the formation of an aldimine ionic species and which is associated with the broad component of the accompanying composite metastable peak. Collision-induced dissociation and deuterium-labelling experiments have provided evidence that the initially generated o-azaxylylene ionic species, both as long-lived and as decomposing ions, have rearranged to the aldimine ionic species via a 1,5-shift of the α-hydrogen atom adjacent to the heterocyclic ring nitrogen atom.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070816
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  • 87
    Digitale Medien
    Digitale Medien
    Gas-phase chemistry of metal carbonyl anions: Reactions of Fe(CO)2- with methanol and its 13C-, D- and 18O-labelled analogues studied by fourier-transform ion cyclotron resonance mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 769-773 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The reactions of the metal dicarbonyl anion Fe(CO)2- with methanol and five of its isotopomers, namely CD3OH, CH3OD, CD3OH and CH318OH have been studied by the use of Fourier-transform ion cyclotron resonance mass spectrometry. Three competitive reaction channels have been identified in these trapped-ion/molecule studies which, for methanol, lead to the formation of three primary reaction products, namely [HFe(CO)(OCH)3]- formed in a decarbonylation channel; Fe(CO)3- in a channel involving C—H and O—H bond activations and bis-dehydrogenation of a collision complex; and also [(CH2O)Fe(CO)2]- in a separate channel involving the elimination of a single H2 molecule. The primary product ion [HFe(CO)(OCH)3]- further reacts with methanol to give a bis-alkoxy substituted metal carbonyl ion [(CH3O)2Fe(CO)]- at trapping times of several seconds. Complex deuterium isotope effects of an interactive nature with respect to the three reaction channels also have been observed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070817
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  • 88
    Digitale Medien
    Digitale Medien
    Verification of the position of the phosphate group in some synthetic phosphopeptides by fast-atom bombardment and tandem mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 774-779 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Some synthetically obtained linear and cyclic phosphopeptides of low molecular weight have been studied by fast-atom bombardment and tandem mass spectrometry to verify the position of the phosphate group in these compounds. Based upon the occurrence/non-occurrence of loss of phosphoric acid from low abundance fragment ions induced by low- and high-energy collisions with target gases, it is shown that the position of the phosphate group in the phosphopeptides studied can be determined unequivocally.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070818
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  • 89
    Digitale Medien
    Digitale Medien
    Double-electron transfer from Xe to Xe4+ at low energies as observed in the trap of a fourier-transform ion cyclotron resonance mass spectrometer (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 780-783 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Multiply charged Xen+ ions with n≤5 were generated by electron impact on xenon gas in the external ion source of a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. These ions were transferred to and trapped in the low pressure FT-ICR cell. Subsequently, xenon ions with a particular mass and charge state were selected by ejection of all other unwanted ions from the FT-ICR cell and allowed to react with neutral xenon atoms. It was found that, in the interactions between Xe4+ ions and neutral xenon atoms, not only does a single electron transfer take place, but also a double electron transfer.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070819
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  • 90
    Digitale Medien
    Digitale Medien
    Recent events (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 784-785 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Formation of the European Mass Spectrometry Society, Budapest 25 April 1993.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070821
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  • 91
    Digitale Medien
    Digitale Medien
    Masthead (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993) 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070901
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  • 92
    Digitale Medien
    Digitale Medien
    Calendar of events (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. ii 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070822
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  • 93
    Digitale Medien
    Digitale Medien
    Mass spectrometry of some C6F13-compounds and their C6H13-analogsPaper delivered at the 11th Informal Meeting on Mass Spectrometry, Budapest, 1993 (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 789-794 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The 70 eV electron ionization mass spectrometric behaviour of some C6F13-compounds has been studied in detail by means of mass-analyzed ion kinetic energy spectroscopy and compared with that of the C6H13-analogs. As a general trend, the incorporation of fluorine leads to a strengthening of the alkyl chain; in fact the extensive primary fragmentation processes related to the chain cleavages observed for hydrocarbon derivatives are strongly suppressed in the case of the corresponding fluorocarbons. Moreover, the interaction of fluorine with functional groups leads to unexpected decomposition processes. The —CH2—CF2— bond, often considered in condensed-phase chemistry as a weak point in the molecule, never undergoes fragmentation.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070902
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  • 94
    Digitale Medien
    Digitale Medien
    Enthalpies of formation of the negative ions MnO2-, MnO3- and MnO4- as determined by the ion/molecule equilibrium method (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 800-804 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Admixture of potassium chromate to manganese oxide has allowed us to generate measurable concentrations of the negative ions MnO2-, MnO3-, and MnO4- in the vapours over manganese oxide at 1300-1500 K. Equilibrium constants with the participation of these ions have been measured and the enthalpies of formation {ΔfHm°(MnO2-, 0 K) = (-266±13)kJmol-1, δfHm°,(MnO3-, 0 K) = (-538±14) kJmol-1, δfHm°(MnO4-, 0 K) = (-669±17)kJ mol-1}, dissociation energies and the electron affinity (EA) of MnO2 {EA = 292kJ mol-1} have been estimated. The use of manganese-containing negative ions to measure the activity of manganese oxides is discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070904
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  • 95
    Digitale Medien
    Digitale Medien
    Radical molecular anions formed from organic molecules under negative-ion fast-atom bombardment conditions: An unexpected finding during studies on the metabolism of bis(2-ethylhexyl) phthalate (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 812-814 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Urinary metabolites of bis(2-ethylhexyl) phthalate were studied using fast-atom bombardment mass spectrometry (FAB-MS). It was found that the ß-glucosides of mono(2-ethyl-5-hydroxyhexyl) phthalate and mono(2-ethyl-5-oxohexyl) phthalate gave radical molecular unions, M -·, under negative-ion FAB conditions. This was also shown to occur for the methyl ester of mono(2-ethylhexyl) phthalate ß-glucuronide, an artefact formed during the work-up procedure.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070906
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  • 96
    Digitale Medien
    Digitale Medien
    A new type of graphite emitter for field ionization/field desorption mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 805-811 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A new type of field ionization/field desorption (FI/FD) emitter made of graphite is proposed. The method of emitter preparation is based on the observation that, on the fracture-surface of graphite, fine microcrystallites are exposed, the sharpness of which is sufficient to provide, under conditions of field mass spectrometry, field strength values sufficient for the ionization of molecules by a tunnelling mechanism. The ease of preparation and handling of such graphite emitters is noteworthy. The efficiency of the graphite emitters is illustrated by examples of FI/FD measurements of a number of substances with different physical and chemical parameters, producing M+·, MH+, MCat+, Cat+, MnH+ types of ions. The main advantage of graphite emitters is seen as the possibility of precise control and direct measurement of the emitter temperature, which facilitates the obtaining of mass-thermograms of thermodegradation and the study of various temperature-dependent processes. Some specific potentialities of graphite emitters are outlined, namely the feasibility of direct analysis of organic inclusions in emitter material and switching to the surface-ionization mode.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070905
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  • 97
    Digitale Medien
    Digitale Medien
    Analysis of the squalestatins by on-line packed capillary liquid chromatography/dynamic liquid secondary-ion/mass spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 492-495 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: A mixture of four squalestatins was separated and characterized by gradient-packed capillary liquid chroma-tography combined with dynamic liquid secondary-ion mass spectrometry (LSIMS). Thioglycerol/glycerol matrix was added post-column. Negative-ion LSIMS was found to afford spectra typified by strong molecular ions with structurally informative fragments. The new method showed improvements in sensitivity and specificity for this class of compound when compared to existing thermospray methods.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070618
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  • 98
    Digitale Medien
    Digitale Medien
    The mass spectrometry service centre at Swansea: A small jewel in the crown of the science and engineering research council (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 515-518 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The National Centre, set up by the Science and Engineering Reasearch Council in 1985, currently services the specialist mass spectrometry requirements of over 140 chemistry research teams, covering most of the British universities and carrying out about 9500 analyses each year, using mainly soft-ionization techniques. Its work has featured in 1276 publilcatons during the past three years and the Centre has become invaluable to the progress of many research teams in Britain.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070623
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  • 99
    Digitale Medien
    Digitale Medien
    Isotope ratio measurements in lead using three-photon one-colour resonance ionization mass spectrometryBritish Crown Copyright 1993/MOD. Published with the permission of the Controller of Her Britannic Majesty's Stationery Office. (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 524-527 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Resonance effects on measured isotope ratios in lead using three-photon one-colour resonance ionization mass spectrometry are discussed. The shape of the ionization signal is considered for the case of a non-monochromatic laser field. The intensity of the laser radiation is adjusted to be low enough not to cause saturation of the transitions. The variation of the measured isotope ratio as a function of laser frequency is considered. It is shown that the deviation of the measured from the expected isotope ratio, for a Lorentzian laser lineshape equals the ratio of the isotope shift to the laser bandwidth. Unfortunately, the background noise in the experiments makes verification of this behaviour difficult for the isotopes of low abundance.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070625
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  • 100
    Digitale Medien
    Digitale Medien
    State compositional analysis of diatomic cation beams using charge-inversion spectrometry (1993)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 7 (1993), S. 542-547 
    Details
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The utility of charge-inversion Spectrometry in the state analysis of diatomic cation beams is demonstrated by a brief summary and by reference to novel work on beams of NO+, SH+, CS+ and CI2+. A previously unknown state, of 3.5 eV relative energy and presumably of 4Σ+ symmetry was observed to be populated in a beam of CS+ ions formed from CS2. Evidence for the longevity ( 〉 10-5s) of the Ã2II state of CS+ and the b̃3II state of NO+ is also presented.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/rcm.1290070628
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