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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of impurities in a synthetic renin substrate peptide by fast-atom bombardment mass spectrometry and hybrid tandem mass spectrometry (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 314-319 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fast-atom bombardment mass spectrometry of a synthetic renin substrate decapeptide (Pro-His-Pro-Phe-His-Leu-Val-Ile-His-D-Lys) indicated the presence of several of side-products, including a component 12 Da higher in mass. Low-energy collisionally activated decomposition analyses were performed using a hybrid tanden, instrument and demonstrated that the heavier side product had two components, in which the structural modification was either at the N- or the C-terminus. Additional analyses of the N-acetyl derivative indicated that for each component the strucutrual modification blcoked a site of N-acetylation. It is suggested that the formation of these side products is attributable to the generation of formaldehyde, during removal of the histidine protecting group (benzyloxymethyl), which reacts with the N-terminus of the peptide to give an imidazolidinone structure or with the D-lysine ε-amine group to yield an imine. While the precise genesis of the side-products remains speculative, it is clear that the combined strategy of derivatization and tandem mass spectrometry has allowed structural conclusions concerning individual components of an isobaric mixture.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290030912
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  • 2
    Electronic Resource
    Electronic Resource
    Electrospray tandem mass spectrometry in the diagnosis of organic acidemiasPaper presented in part at the British Mass Spectrometry Society Meeting, Canterbury, 1993. (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 129-133 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A novel procedure based on electrospray tandem mass spectrometry (ESI-MS/MS) has been used in the diagnosis of organic acidemias. The method is based on the determination of acylcarnitine profiles from blood spots collected on Guthrie cards. The acylcarnitines are extracted with methanol, derivatized to their butyl esters and analyzed by ESI-MS/MS. Precursor-ion scanning of the common fragment at m/z 85 of the butyl esters yields highly diagnostic acylcarnitine profiles. Analysis time is one minute per sample and is fully automated. Examples are given of normal profiles, of profiles from two patients with fatty acid oxidation defects, and of a case of propionic acidemia. The technique is simple, rapid and specific, and shows potential for routine application in neonatal screening of organic acidemias.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080124
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Recognition of quaternary ammonium compounds using mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 65-70 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Liquid secondary-ion mass spectrometry (LSIMS) experiments were performed on a series of model quaternary ammonium chlorides [MQ+Cl-] in order to develop a strategy, via an understanding of cluster-ion formation, for recognition of quarternary ammonium structures. Model structures contained a single quaternary site and various other structural features (for example, conjugated quaternary systems and carboxylic acid groups), using amine hydrochlorides as controls. Cluster ions were examined with both positive- and negative-ion LSIMS, using a range of matrix modifiers. Precursor scans, or ‘molecular weight confirmation scans’, of MQ+ (the charged molecular ion of quaternary ammonium compounds) and [M+H]+ ions were used to assist in the observation of cluster ions and to unambiguously demonstrate precursor/product relationships. Positive-ion experiments typically showed dimeric clusters of [2MQ+ A]+ (A=anion) and [2MQ-H]+ ions, while negative ion experiments produced [MQ + 2A]- ions. Observation of these cluster ions coupled with the lack of an [M-H]- ion are a distinguishing feature of quaternary amines. Additional cluster ions were targeted for distinguishing between protonated amines and quaternary amonium compounds containing a carboxylic acid group. A strategy for recognizing and distinguishing quaternary ammonium structures using LSIMS is proposed, and some initial experiments with thermospray and electrospray are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080113
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  • 4
    Electronic Resource
    Electronic Resource
    Matrix-assisted laser desorption ionization for rapid determination of the sequences of biologically active peptides isolated from support-bound combinatorial peptide libraries (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 77-81 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A termination synthesis approach has been developed to encode each resin bead in support-bound combinatorial peptide libraries with the information needed to establish the sequence of the full-length products also contained on the beads. Matrix-assisted laser desorption ionization mass spectrometry was then used to rapidly read the appropriate sequences. In addition to rapid peptide sequencing, the technique allows direct assessment of the quality of the synthetic library, since deletion peptides, side-reaction products and incomplete-deprotection products are readily observed. An anti-gp120 monoclonal antibody was screened against a hexapeptide library, and eight active peptides were isolated. Six of the eight peptides were shown to possess the exact recognition sequence for the antibody.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080115
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of enzymatic DNA sequencing reactions by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (1995)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 9 (1995), S. 942-947 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The products from base-specific, dideoxy-nucleotide chain-termination DNA sequencing reactions catalyzed by the modified T7 DNA polymerase have been analyzed by using the technique of matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. Preliminary experiments were performed to determine detection limits for a synthetic mixture of mixed-base single-stranded DNA which contained a 14-mer, a 21-mer, and a 41-mer; acceptable spectra, showing peaks for each component, were obtainable for samples that contained as little as 5 fmol per component. Initial sequencing reactions were therefore carried out on 2-pmol amounts of a short synthetic template that was 45 nucleotides in length, employing 2 pmol of 12-mer as the primer strand. This provided readable sequence information out to the 19th base past the primer. Using a 21-mer primer, nearly the entire sequence of the template could be read.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290091015
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  • 6
    Electronic Resource
    Electronic Resource
    Introduction to computer-assisted experimentation. Kenneth L. ratzlaff. Wiley-Interscience: New York, NY, 1987. 438 pp + figs and tables. $44.95 (1987)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 1 (1987), S. iv 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290010213
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  • 7
    Electronic Resource
    Electronic Resource
    Application of liquid chromatography/thermospray mass spectrometry to studies on the formation of glutathione and cysteine conjugates from monomethylcarbamate metabolites of bambuterol (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 360-363 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Liquid chromatography/thermospray mass spectrometry (LC/TSP-MS) has been used to identify and study the rates of formation of S-(N-methylcarbamoyl) cysteine and S-(N-methylcarbamoyl)glutathione as products of the in vitro reaction of cysteine and glutathione, respectively, with two monomethylcarbamate metabolites of the bronchodilator pro-drug bambuterol. The conjugates of interest afforded MH+ species and yielded abundant structurally informative fragment ions which were employed in the development of quantitative, selected-ion monitoring assays. It is concluded that LC/TSP-MS represents a rapid and convenient approach to the direct aqueous-phase analysis of the class of S-(N-alkylcarbamoyl) conjugates of cysteine and glutathione.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290031012
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  • 8
    Electronic Resource
    Electronic Resource
    Improved detection of glucuronide and glutathione conjugates with thermospray ionization following esterification (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 371-376 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Analysis by thermospray of glucuronide and glutathione conjugates as the corresponding methyl-, propyl-, or hexyl esters is demonstrated to yield a remarkable increase in positive pseudomolecular ion production and to result in a dramatic improvement in detectability of these thermally labile compounds as intact molecular structures. In the most extreme examples a 450-fold increase in the [M + NH4]+ ion intensity was observed for mycophenolic acid glucuronide bis-propyl esters vs. the native conjugate and an 860-fold increase in the [M + H]+ ion intensity was achieved for acetaminophen glutathione bis-hexyl ester vs. the native conjugate. Following esterification, seventeen of the eighteen glucuronide esters analyzed demonstrated an increase in totalion-current yield ranging from 1.1- to 8.3-fold while eighteen of the twenty-one glutathione esters examined demonstrated an increase in totalion-current yield from 2.0- to 26.3-fold. For both types of conjugates a trend in increased relative abundance of the positive pseudomolecular ion intensity is observed as the hydrophobicity of the ester increases from methyl to hexyl. For the glutathione conjugate esters, the [M + H]+ ion represented the base peak in the mass spectra of the majority of samples analyzed. This approach improves the protonated- or ammoniated-molecular-ion abundances of the conjugates to such an extent that it provides a means for unambiguous molecular weight assignments to be made. Although the exact mechanism(s) for the observed phenomenon is not known, it appears that the improvement in sensitivity for the conjugate esters over the corresponding native conjugates involves an increase in pseudomolecular-ion stability and also in part an increased ionization efficiency of the esterified molecule.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080506
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and applications of isotopically labelled compounds (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 195-195 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290020909
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  • 10
    Electronic Resource
    Electronic Resource
    Isotope effects in the bimolecular reactions of gaseous ions. Concepts, techniques, and reactions (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Mass Spectrometry Reviews 14 (1995), S. 353-382 
    Details
    ISSN: 0277-7037
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Foundations of isotope effects are examined in terms of concepts, models, and theories. Leading instrumental methods for bimoleculur reactions are reviewed: the guided ion beum mass spectrometer (GIBMS) and the selected ion flow tube (SIFT). In their most elaborate forms, both methods can select the translational energies of the reacting ions and the temperatures of the neutral molecules. This capability gives extraordinary control over bimolecular ion/molecule reactions. Experiments on simple systems can sometimes identify the effects of particular forms of internal energy. Isotope effects appear in numerous reaction types and behave in several ways as functions of ion translational energy and temperature. For endothermic reactions, they can become very large at low temperatures, a matter of much interest in astrophysics. © 1996 John Wiley & Sons, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mas.1280140602
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